xref: /openbmc/linux/drivers/mtd/nand/raw/omap2.c (revision e3d786a3)
1 /*
2  * Copyright © 2004 Texas Instruments, Jian Zhang <jzhang@ti.com>
3  * Copyright © 2004 Micron Technology Inc.
4  * Copyright © 2004 David Brownell
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 
11 #include <linux/platform_device.h>
12 #include <linux/dmaengine.h>
13 #include <linux/dma-mapping.h>
14 #include <linux/delay.h>
15 #include <linux/gpio/consumer.h>
16 #include <linux/module.h>
17 #include <linux/interrupt.h>
18 #include <linux/jiffies.h>
19 #include <linux/sched.h>
20 #include <linux/mtd/mtd.h>
21 #include <linux/mtd/rawnand.h>
22 #include <linux/mtd/partitions.h>
23 #include <linux/omap-dma.h>
24 #include <linux/io.h>
25 #include <linux/slab.h>
26 #include <linux/of.h>
27 #include <linux/of_device.h>
28 
29 #include <linux/mtd/nand_bch.h>
30 #include <linux/platform_data/elm.h>
31 
32 #include <linux/omap-gpmc.h>
33 #include <linux/platform_data/mtd-nand-omap2.h>
34 
35 #define	DRIVER_NAME	"omap2-nand"
36 #define	OMAP_NAND_TIMEOUT_MS	5000
37 
38 #define NAND_Ecc_P1e		(1 << 0)
39 #define NAND_Ecc_P2e		(1 << 1)
40 #define NAND_Ecc_P4e		(1 << 2)
41 #define NAND_Ecc_P8e		(1 << 3)
42 #define NAND_Ecc_P16e		(1 << 4)
43 #define NAND_Ecc_P32e		(1 << 5)
44 #define NAND_Ecc_P64e		(1 << 6)
45 #define NAND_Ecc_P128e		(1 << 7)
46 #define NAND_Ecc_P256e		(1 << 8)
47 #define NAND_Ecc_P512e		(1 << 9)
48 #define NAND_Ecc_P1024e		(1 << 10)
49 #define NAND_Ecc_P2048e		(1 << 11)
50 
51 #define NAND_Ecc_P1o		(1 << 16)
52 #define NAND_Ecc_P2o		(1 << 17)
53 #define NAND_Ecc_P4o		(1 << 18)
54 #define NAND_Ecc_P8o		(1 << 19)
55 #define NAND_Ecc_P16o		(1 << 20)
56 #define NAND_Ecc_P32o		(1 << 21)
57 #define NAND_Ecc_P64o		(1 << 22)
58 #define NAND_Ecc_P128o		(1 << 23)
59 #define NAND_Ecc_P256o		(1 << 24)
60 #define NAND_Ecc_P512o		(1 << 25)
61 #define NAND_Ecc_P1024o		(1 << 26)
62 #define NAND_Ecc_P2048o		(1 << 27)
63 
64 #define TF(value)	(value ? 1 : 0)
65 
66 #define P2048e(a)	(TF(a & NAND_Ecc_P2048e)	<< 0)
67 #define P2048o(a)	(TF(a & NAND_Ecc_P2048o)	<< 1)
68 #define P1e(a)		(TF(a & NAND_Ecc_P1e)		<< 2)
69 #define P1o(a)		(TF(a & NAND_Ecc_P1o)		<< 3)
70 #define P2e(a)		(TF(a & NAND_Ecc_P2e)		<< 4)
71 #define P2o(a)		(TF(a & NAND_Ecc_P2o)		<< 5)
72 #define P4e(a)		(TF(a & NAND_Ecc_P4e)		<< 6)
73 #define P4o(a)		(TF(a & NAND_Ecc_P4o)		<< 7)
74 
75 #define P8e(a)		(TF(a & NAND_Ecc_P8e)		<< 0)
76 #define P8o(a)		(TF(a & NAND_Ecc_P8o)		<< 1)
77 #define P16e(a)		(TF(a & NAND_Ecc_P16e)		<< 2)
78 #define P16o(a)		(TF(a & NAND_Ecc_P16o)		<< 3)
79 #define P32e(a)		(TF(a & NAND_Ecc_P32e)		<< 4)
80 #define P32o(a)		(TF(a & NAND_Ecc_P32o)		<< 5)
81 #define P64e(a)		(TF(a & NAND_Ecc_P64e)		<< 6)
82 #define P64o(a)		(TF(a & NAND_Ecc_P64o)		<< 7)
83 
84 #define P128e(a)	(TF(a & NAND_Ecc_P128e)		<< 0)
85 #define P128o(a)	(TF(a & NAND_Ecc_P128o)		<< 1)
86 #define P256e(a)	(TF(a & NAND_Ecc_P256e)		<< 2)
87 #define P256o(a)	(TF(a & NAND_Ecc_P256o)		<< 3)
88 #define P512e(a)	(TF(a & NAND_Ecc_P512e)		<< 4)
89 #define P512o(a)	(TF(a & NAND_Ecc_P512o)		<< 5)
90 #define P1024e(a)	(TF(a & NAND_Ecc_P1024e)	<< 6)
91 #define P1024o(a)	(TF(a & NAND_Ecc_P1024o)	<< 7)
92 
93 #define P8e_s(a)	(TF(a & NAND_Ecc_P8e)		<< 0)
94 #define P8o_s(a)	(TF(a & NAND_Ecc_P8o)		<< 1)
95 #define P16e_s(a)	(TF(a & NAND_Ecc_P16e)		<< 2)
96 #define P16o_s(a)	(TF(a & NAND_Ecc_P16o)		<< 3)
97 #define P1e_s(a)	(TF(a & NAND_Ecc_P1e)		<< 4)
98 #define P1o_s(a)	(TF(a & NAND_Ecc_P1o)		<< 5)
99 #define P2e_s(a)	(TF(a & NAND_Ecc_P2e)		<< 6)
100 #define P2o_s(a)	(TF(a & NAND_Ecc_P2o)		<< 7)
101 
102 #define P4e_s(a)	(TF(a & NAND_Ecc_P4e)		<< 0)
103 #define P4o_s(a)	(TF(a & NAND_Ecc_P4o)		<< 1)
104 
105 #define	PREFETCH_CONFIG1_CS_SHIFT	24
106 #define	ECC_CONFIG_CS_SHIFT		1
107 #define	CS_MASK				0x7
108 #define	ENABLE_PREFETCH			(0x1 << 7)
109 #define	DMA_MPU_MODE_SHIFT		2
110 #define	ECCSIZE0_SHIFT			12
111 #define	ECCSIZE1_SHIFT			22
112 #define	ECC1RESULTSIZE			0x1
113 #define	ECCCLEAR			0x100
114 #define	ECC1				0x1
115 #define	PREFETCH_FIFOTHRESHOLD_MAX	0x40
116 #define	PREFETCH_FIFOTHRESHOLD(val)	((val) << 8)
117 #define	PREFETCH_STATUS_COUNT(val)	(val & 0x00003fff)
118 #define	PREFETCH_STATUS_FIFO_CNT(val)	((val >> 24) & 0x7F)
119 #define	STATUS_BUFF_EMPTY		0x00000001
120 
121 #define SECTOR_BYTES		512
122 /* 4 bit padding to make byte aligned, 56 = 52 + 4 */
123 #define BCH4_BIT_PAD		4
124 
125 /* GPMC ecc engine settings for read */
126 #define BCH_WRAPMODE_1		1	/* BCH wrap mode 1 */
127 #define BCH8R_ECC_SIZE0		0x1a	/* ecc_size0 = 26 */
128 #define BCH8R_ECC_SIZE1		0x2	/* ecc_size1 = 2 */
129 #define BCH4R_ECC_SIZE0		0xd	/* ecc_size0 = 13 */
130 #define BCH4R_ECC_SIZE1		0x3	/* ecc_size1 = 3 */
131 
132 /* GPMC ecc engine settings for write */
133 #define BCH_WRAPMODE_6		6	/* BCH wrap mode 6 */
134 #define BCH_ECC_SIZE0		0x0	/* ecc_size0 = 0, no oob protection */
135 #define BCH_ECC_SIZE1		0x20	/* ecc_size1 = 32 */
136 
137 #define BADBLOCK_MARKER_LENGTH		2
138 
139 static u_char bch16_vector[] = {0xf5, 0x24, 0x1c, 0xd0, 0x61, 0xb3, 0xf1, 0x55,
140 				0x2e, 0x2c, 0x86, 0xa3, 0xed, 0x36, 0x1b, 0x78,
141 				0x48, 0x76, 0xa9, 0x3b, 0x97, 0xd1, 0x7a, 0x93,
142 				0x07, 0x0e};
143 static u_char bch8_vector[] = {0xf3, 0xdb, 0x14, 0x16, 0x8b, 0xd2, 0xbe, 0xcc,
144 	0xac, 0x6b, 0xff, 0x99, 0x7b};
145 static u_char bch4_vector[] = {0x00, 0x6b, 0x31, 0xdd, 0x41, 0xbc, 0x10};
146 
147 struct omap_nand_info {
148 	struct nand_chip		nand;
149 	struct platform_device		*pdev;
150 
151 	int				gpmc_cs;
152 	bool				dev_ready;
153 	enum nand_io			xfer_type;
154 	int				devsize;
155 	enum omap_ecc			ecc_opt;
156 	struct device_node		*elm_of_node;
157 
158 	unsigned long			phys_base;
159 	struct completion		comp;
160 	struct dma_chan			*dma;
161 	int				gpmc_irq_fifo;
162 	int				gpmc_irq_count;
163 	enum {
164 		OMAP_NAND_IO_READ = 0,	/* read */
165 		OMAP_NAND_IO_WRITE,	/* write */
166 	} iomode;
167 	u_char				*buf;
168 	int					buf_len;
169 	/* Interface to GPMC */
170 	struct gpmc_nand_regs		reg;
171 	struct gpmc_nand_ops		*ops;
172 	bool				flash_bbt;
173 	/* fields specific for BCHx_HW ECC scheme */
174 	struct device			*elm_dev;
175 	/* NAND ready gpio */
176 	struct gpio_desc		*ready_gpiod;
177 };
178 
179 static inline struct omap_nand_info *mtd_to_omap(struct mtd_info *mtd)
180 {
181 	return container_of(mtd_to_nand(mtd), struct omap_nand_info, nand);
182 }
183 
184 /**
185  * omap_prefetch_enable - configures and starts prefetch transfer
186  * @cs: cs (chip select) number
187  * @fifo_th: fifo threshold to be used for read/ write
188  * @dma_mode: dma mode enable (1) or disable (0)
189  * @u32_count: number of bytes to be transferred
190  * @is_write: prefetch read(0) or write post(1) mode
191  */
192 static int omap_prefetch_enable(int cs, int fifo_th, int dma_mode,
193 	unsigned int u32_count, int is_write, struct omap_nand_info *info)
194 {
195 	u32 val;
196 
197 	if (fifo_th > PREFETCH_FIFOTHRESHOLD_MAX)
198 		return -1;
199 
200 	if (readl(info->reg.gpmc_prefetch_control))
201 		return -EBUSY;
202 
203 	/* Set the amount of bytes to be prefetched */
204 	writel(u32_count, info->reg.gpmc_prefetch_config2);
205 
206 	/* Set dma/mpu mode, the prefetch read / post write and
207 	 * enable the engine. Set which cs is has requested for.
208 	 */
209 	val = ((cs << PREFETCH_CONFIG1_CS_SHIFT) |
210 		PREFETCH_FIFOTHRESHOLD(fifo_th) | ENABLE_PREFETCH |
211 		(dma_mode << DMA_MPU_MODE_SHIFT) | (is_write & 0x1));
212 	writel(val, info->reg.gpmc_prefetch_config1);
213 
214 	/*  Start the prefetch engine */
215 	writel(0x1, info->reg.gpmc_prefetch_control);
216 
217 	return 0;
218 }
219 
220 /**
221  * omap_prefetch_reset - disables and stops the prefetch engine
222  */
223 static int omap_prefetch_reset(int cs, struct omap_nand_info *info)
224 {
225 	u32 config1;
226 
227 	/* check if the same module/cs is trying to reset */
228 	config1 = readl(info->reg.gpmc_prefetch_config1);
229 	if (((config1 >> PREFETCH_CONFIG1_CS_SHIFT) & CS_MASK) != cs)
230 		return -EINVAL;
231 
232 	/* Stop the PFPW engine */
233 	writel(0x0, info->reg.gpmc_prefetch_control);
234 
235 	/* Reset/disable the PFPW engine */
236 	writel(0x0, info->reg.gpmc_prefetch_config1);
237 
238 	return 0;
239 }
240 
241 /**
242  * omap_hwcontrol - hardware specific access to control-lines
243  * @chip: NAND chip object
244  * @cmd: command to device
245  * @ctrl:
246  * NAND_NCE: bit 0 -> don't care
247  * NAND_CLE: bit 1 -> Command Latch
248  * NAND_ALE: bit 2 -> Address Latch
249  *
250  * NOTE: boards may use different bits for these!!
251  */
252 static void omap_hwcontrol(struct nand_chip *chip, int cmd, unsigned int ctrl)
253 {
254 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
255 
256 	if (cmd != NAND_CMD_NONE) {
257 		if (ctrl & NAND_CLE)
258 			writeb(cmd, info->reg.gpmc_nand_command);
259 
260 		else if (ctrl & NAND_ALE)
261 			writeb(cmd, info->reg.gpmc_nand_address);
262 
263 		else /* NAND_NCE */
264 			writeb(cmd, info->reg.gpmc_nand_data);
265 	}
266 }
267 
268 /**
269  * omap_read_buf8 - read data from NAND controller into buffer
270  * @mtd: MTD device structure
271  * @buf: buffer to store date
272  * @len: number of bytes to read
273  */
274 static void omap_read_buf8(struct mtd_info *mtd, u_char *buf, int len)
275 {
276 	struct nand_chip *nand = mtd_to_nand(mtd);
277 
278 	ioread8_rep(nand->legacy.IO_ADDR_R, buf, len);
279 }
280 
281 /**
282  * omap_write_buf8 - write buffer to NAND controller
283  * @mtd: MTD device structure
284  * @buf: data buffer
285  * @len: number of bytes to write
286  */
287 static void omap_write_buf8(struct mtd_info *mtd, const u_char *buf, int len)
288 {
289 	struct omap_nand_info *info = mtd_to_omap(mtd);
290 	u_char *p = (u_char *)buf;
291 	bool status;
292 
293 	while (len--) {
294 		iowrite8(*p++, info->nand.legacy.IO_ADDR_W);
295 		/* wait until buffer is available for write */
296 		do {
297 			status = info->ops->nand_writebuffer_empty();
298 		} while (!status);
299 	}
300 }
301 
302 /**
303  * omap_read_buf16 - read data from NAND controller into buffer
304  * @mtd: MTD device structure
305  * @buf: buffer to store date
306  * @len: number of bytes to read
307  */
308 static void omap_read_buf16(struct mtd_info *mtd, u_char *buf, int len)
309 {
310 	struct nand_chip *nand = mtd_to_nand(mtd);
311 
312 	ioread16_rep(nand->legacy.IO_ADDR_R, buf, len / 2);
313 }
314 
315 /**
316  * omap_write_buf16 - write buffer to NAND controller
317  * @mtd: MTD device structure
318  * @buf: data buffer
319  * @len: number of bytes to write
320  */
321 static void omap_write_buf16(struct mtd_info *mtd, const u_char * buf, int len)
322 {
323 	struct omap_nand_info *info = mtd_to_omap(mtd);
324 	u16 *p = (u16 *) buf;
325 	bool status;
326 	/* FIXME try bursts of writesw() or DMA ... */
327 	len >>= 1;
328 
329 	while (len--) {
330 		iowrite16(*p++, info->nand.legacy.IO_ADDR_W);
331 		/* wait until buffer is available for write */
332 		do {
333 			status = info->ops->nand_writebuffer_empty();
334 		} while (!status);
335 	}
336 }
337 
338 /**
339  * omap_read_buf_pref - read data from NAND controller into buffer
340  * @chip: NAND chip object
341  * @buf: buffer to store date
342  * @len: number of bytes to read
343  */
344 static void omap_read_buf_pref(struct nand_chip *chip, u_char *buf, int len)
345 {
346 	struct mtd_info *mtd = nand_to_mtd(chip);
347 	struct omap_nand_info *info = mtd_to_omap(mtd);
348 	uint32_t r_count = 0;
349 	int ret = 0;
350 	u32 *p = (u32 *)buf;
351 
352 	/* take care of subpage reads */
353 	if (len % 4) {
354 		if (info->nand.options & NAND_BUSWIDTH_16)
355 			omap_read_buf16(mtd, buf, len % 4);
356 		else
357 			omap_read_buf8(mtd, buf, len % 4);
358 		p = (u32 *) (buf + len % 4);
359 		len -= len % 4;
360 	}
361 
362 	/* configure and start prefetch transfer */
363 	ret = omap_prefetch_enable(info->gpmc_cs,
364 			PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x0, info);
365 	if (ret) {
366 		/* PFPW engine is busy, use cpu copy method */
367 		if (info->nand.options & NAND_BUSWIDTH_16)
368 			omap_read_buf16(mtd, (u_char *)p, len);
369 		else
370 			omap_read_buf8(mtd, (u_char *)p, len);
371 	} else {
372 		do {
373 			r_count = readl(info->reg.gpmc_prefetch_status);
374 			r_count = PREFETCH_STATUS_FIFO_CNT(r_count);
375 			r_count = r_count >> 2;
376 			ioread32_rep(info->nand.legacy.IO_ADDR_R, p, r_count);
377 			p += r_count;
378 			len -= r_count << 2;
379 		} while (len);
380 		/* disable and stop the PFPW engine */
381 		omap_prefetch_reset(info->gpmc_cs, info);
382 	}
383 }
384 
385 /**
386  * omap_write_buf_pref - write buffer to NAND controller
387  * @chip: NAND chip object
388  * @buf: data buffer
389  * @len: number of bytes to write
390  */
391 static void omap_write_buf_pref(struct nand_chip *chip, const u_char *buf,
392 				int len)
393 {
394 	struct mtd_info *mtd = nand_to_mtd(chip);
395 	struct omap_nand_info *info = mtd_to_omap(mtd);
396 	uint32_t w_count = 0;
397 	int i = 0, ret = 0;
398 	u16 *p = (u16 *)buf;
399 	unsigned long tim, limit;
400 	u32 val;
401 
402 	/* take care of subpage writes */
403 	if (len % 2 != 0) {
404 		writeb(*buf, info->nand.legacy.IO_ADDR_W);
405 		p = (u16 *)(buf + 1);
406 		len--;
407 	}
408 
409 	/*  configure and start prefetch transfer */
410 	ret = omap_prefetch_enable(info->gpmc_cs,
411 			PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x1, info);
412 	if (ret) {
413 		/* PFPW engine is busy, use cpu copy method */
414 		if (info->nand.options & NAND_BUSWIDTH_16)
415 			omap_write_buf16(mtd, (u_char *)p, len);
416 		else
417 			omap_write_buf8(mtd, (u_char *)p, len);
418 	} else {
419 		while (len) {
420 			w_count = readl(info->reg.gpmc_prefetch_status);
421 			w_count = PREFETCH_STATUS_FIFO_CNT(w_count);
422 			w_count = w_count >> 1;
423 			for (i = 0; (i < w_count) && len; i++, len -= 2)
424 				iowrite16(*p++, info->nand.legacy.IO_ADDR_W);
425 		}
426 		/* wait for data to flushed-out before reset the prefetch */
427 		tim = 0;
428 		limit = (loops_per_jiffy *
429 					msecs_to_jiffies(OMAP_NAND_TIMEOUT_MS));
430 		do {
431 			cpu_relax();
432 			val = readl(info->reg.gpmc_prefetch_status);
433 			val = PREFETCH_STATUS_COUNT(val);
434 		} while (val && (tim++ < limit));
435 
436 		/* disable and stop the PFPW engine */
437 		omap_prefetch_reset(info->gpmc_cs, info);
438 	}
439 }
440 
441 /*
442  * omap_nand_dma_callback: callback on the completion of dma transfer
443  * @data: pointer to completion data structure
444  */
445 static void omap_nand_dma_callback(void *data)
446 {
447 	complete((struct completion *) data);
448 }
449 
450 /*
451  * omap_nand_dma_transfer: configure and start dma transfer
452  * @mtd: MTD device structure
453  * @addr: virtual address in RAM of source/destination
454  * @len: number of data bytes to be transferred
455  * @is_write: flag for read/write operation
456  */
457 static inline int omap_nand_dma_transfer(struct mtd_info *mtd, void *addr,
458 					unsigned int len, int is_write)
459 {
460 	struct omap_nand_info *info = mtd_to_omap(mtd);
461 	struct dma_async_tx_descriptor *tx;
462 	enum dma_data_direction dir = is_write ? DMA_TO_DEVICE :
463 							DMA_FROM_DEVICE;
464 	struct scatterlist sg;
465 	unsigned long tim, limit;
466 	unsigned n;
467 	int ret;
468 	u32 val;
469 
470 	if (!virt_addr_valid(addr))
471 		goto out_copy;
472 
473 	sg_init_one(&sg, addr, len);
474 	n = dma_map_sg(info->dma->device->dev, &sg, 1, dir);
475 	if (n == 0) {
476 		dev_err(&info->pdev->dev,
477 			"Couldn't DMA map a %d byte buffer\n", len);
478 		goto out_copy;
479 	}
480 
481 	tx = dmaengine_prep_slave_sg(info->dma, &sg, n,
482 		is_write ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
483 		DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
484 	if (!tx)
485 		goto out_copy_unmap;
486 
487 	tx->callback = omap_nand_dma_callback;
488 	tx->callback_param = &info->comp;
489 	dmaengine_submit(tx);
490 
491 	init_completion(&info->comp);
492 
493 	/* setup and start DMA using dma_addr */
494 	dma_async_issue_pending(info->dma);
495 
496 	/*  configure and start prefetch transfer */
497 	ret = omap_prefetch_enable(info->gpmc_cs,
498 		PREFETCH_FIFOTHRESHOLD_MAX, 0x1, len, is_write, info);
499 	if (ret)
500 		/* PFPW engine is busy, use cpu copy method */
501 		goto out_copy_unmap;
502 
503 	wait_for_completion(&info->comp);
504 	tim = 0;
505 	limit = (loops_per_jiffy * msecs_to_jiffies(OMAP_NAND_TIMEOUT_MS));
506 
507 	do {
508 		cpu_relax();
509 		val = readl(info->reg.gpmc_prefetch_status);
510 		val = PREFETCH_STATUS_COUNT(val);
511 	} while (val && (tim++ < limit));
512 
513 	/* disable and stop the PFPW engine */
514 	omap_prefetch_reset(info->gpmc_cs, info);
515 
516 	dma_unmap_sg(info->dma->device->dev, &sg, 1, dir);
517 	return 0;
518 
519 out_copy_unmap:
520 	dma_unmap_sg(info->dma->device->dev, &sg, 1, dir);
521 out_copy:
522 	if (info->nand.options & NAND_BUSWIDTH_16)
523 		is_write == 0 ? omap_read_buf16(mtd, (u_char *) addr, len)
524 			: omap_write_buf16(mtd, (u_char *) addr, len);
525 	else
526 		is_write == 0 ? omap_read_buf8(mtd, (u_char *) addr, len)
527 			: omap_write_buf8(mtd, (u_char *) addr, len);
528 	return 0;
529 }
530 
531 /**
532  * omap_read_buf_dma_pref - read data from NAND controller into buffer
533  * @chip: NAND chip object
534  * @buf: buffer to store date
535  * @len: number of bytes to read
536  */
537 static void omap_read_buf_dma_pref(struct nand_chip *chip, u_char *buf,
538 				   int len)
539 {
540 	struct mtd_info *mtd = nand_to_mtd(chip);
541 
542 	if (len <= mtd->oobsize)
543 		omap_read_buf_pref(chip, buf, len);
544 	else
545 		/* start transfer in DMA mode */
546 		omap_nand_dma_transfer(mtd, buf, len, 0x0);
547 }
548 
549 /**
550  * omap_write_buf_dma_pref - write buffer to NAND controller
551  * @chip: NAND chip object
552  * @buf: data buffer
553  * @len: number of bytes to write
554  */
555 static void omap_write_buf_dma_pref(struct nand_chip *chip, const u_char *buf,
556 				    int len)
557 {
558 	struct mtd_info *mtd = nand_to_mtd(chip);
559 
560 	if (len <= mtd->oobsize)
561 		omap_write_buf_pref(chip, buf, len);
562 	else
563 		/* start transfer in DMA mode */
564 		omap_nand_dma_transfer(mtd, (u_char *)buf, len, 0x1);
565 }
566 
567 /*
568  * omap_nand_irq - GPMC irq handler
569  * @this_irq: gpmc irq number
570  * @dev: omap_nand_info structure pointer is passed here
571  */
572 static irqreturn_t omap_nand_irq(int this_irq, void *dev)
573 {
574 	struct omap_nand_info *info = (struct omap_nand_info *) dev;
575 	u32 bytes;
576 
577 	bytes = readl(info->reg.gpmc_prefetch_status);
578 	bytes = PREFETCH_STATUS_FIFO_CNT(bytes);
579 	bytes = bytes  & 0xFFFC; /* io in multiple of 4 bytes */
580 	if (info->iomode == OMAP_NAND_IO_WRITE) { /* checks for write io */
581 		if (this_irq == info->gpmc_irq_count)
582 			goto done;
583 
584 		if (info->buf_len && (info->buf_len < bytes))
585 			bytes = info->buf_len;
586 		else if (!info->buf_len)
587 			bytes = 0;
588 		iowrite32_rep(info->nand.legacy.IO_ADDR_W, (u32 *)info->buf,
589 			      bytes >> 2);
590 		info->buf = info->buf + bytes;
591 		info->buf_len -= bytes;
592 
593 	} else {
594 		ioread32_rep(info->nand.legacy.IO_ADDR_R, (u32 *)info->buf,
595 			     bytes >> 2);
596 		info->buf = info->buf + bytes;
597 
598 		if (this_irq == info->gpmc_irq_count)
599 			goto done;
600 	}
601 
602 	return IRQ_HANDLED;
603 
604 done:
605 	complete(&info->comp);
606 
607 	disable_irq_nosync(info->gpmc_irq_fifo);
608 	disable_irq_nosync(info->gpmc_irq_count);
609 
610 	return IRQ_HANDLED;
611 }
612 
613 /*
614  * omap_read_buf_irq_pref - read data from NAND controller into buffer
615  * @chip: NAND chip object
616  * @buf: buffer to store date
617  * @len: number of bytes to read
618  */
619 static void omap_read_buf_irq_pref(struct nand_chip *chip, u_char *buf,
620 				   int len)
621 {
622 	struct mtd_info *mtd = nand_to_mtd(chip);
623 	struct omap_nand_info *info = mtd_to_omap(mtd);
624 	int ret = 0;
625 
626 	if (len <= mtd->oobsize) {
627 		omap_read_buf_pref(chip, buf, len);
628 		return;
629 	}
630 
631 	info->iomode = OMAP_NAND_IO_READ;
632 	info->buf = buf;
633 	init_completion(&info->comp);
634 
635 	/*  configure and start prefetch transfer */
636 	ret = omap_prefetch_enable(info->gpmc_cs,
637 			PREFETCH_FIFOTHRESHOLD_MAX/2, 0x0, len, 0x0, info);
638 	if (ret)
639 		/* PFPW engine is busy, use cpu copy method */
640 		goto out_copy;
641 
642 	info->buf_len = len;
643 
644 	enable_irq(info->gpmc_irq_count);
645 	enable_irq(info->gpmc_irq_fifo);
646 
647 	/* waiting for read to complete */
648 	wait_for_completion(&info->comp);
649 
650 	/* disable and stop the PFPW engine */
651 	omap_prefetch_reset(info->gpmc_cs, info);
652 	return;
653 
654 out_copy:
655 	if (info->nand.options & NAND_BUSWIDTH_16)
656 		omap_read_buf16(mtd, buf, len);
657 	else
658 		omap_read_buf8(mtd, buf, len);
659 }
660 
661 /*
662  * omap_write_buf_irq_pref - write buffer to NAND controller
663  * @chip: NAND chip object
664  * @buf: data buffer
665  * @len: number of bytes to write
666  */
667 static void omap_write_buf_irq_pref(struct nand_chip *chip, const u_char *buf,
668 				    int len)
669 {
670 	struct mtd_info *mtd = nand_to_mtd(chip);
671 	struct omap_nand_info *info = mtd_to_omap(mtd);
672 	int ret = 0;
673 	unsigned long tim, limit;
674 	u32 val;
675 
676 	if (len <= mtd->oobsize) {
677 		omap_write_buf_pref(chip, buf, len);
678 		return;
679 	}
680 
681 	info->iomode = OMAP_NAND_IO_WRITE;
682 	info->buf = (u_char *) buf;
683 	init_completion(&info->comp);
684 
685 	/* configure and start prefetch transfer : size=24 */
686 	ret = omap_prefetch_enable(info->gpmc_cs,
687 		(PREFETCH_FIFOTHRESHOLD_MAX * 3) / 8, 0x0, len, 0x1, info);
688 	if (ret)
689 		/* PFPW engine is busy, use cpu copy method */
690 		goto out_copy;
691 
692 	info->buf_len = len;
693 
694 	enable_irq(info->gpmc_irq_count);
695 	enable_irq(info->gpmc_irq_fifo);
696 
697 	/* waiting for write to complete */
698 	wait_for_completion(&info->comp);
699 
700 	/* wait for data to flushed-out before reset the prefetch */
701 	tim = 0;
702 	limit = (loops_per_jiffy *  msecs_to_jiffies(OMAP_NAND_TIMEOUT_MS));
703 	do {
704 		val = readl(info->reg.gpmc_prefetch_status);
705 		val = PREFETCH_STATUS_COUNT(val);
706 		cpu_relax();
707 	} while (val && (tim++ < limit));
708 
709 	/* disable and stop the PFPW engine */
710 	omap_prefetch_reset(info->gpmc_cs, info);
711 	return;
712 
713 out_copy:
714 	if (info->nand.options & NAND_BUSWIDTH_16)
715 		omap_write_buf16(mtd, buf, len);
716 	else
717 		omap_write_buf8(mtd, buf, len);
718 }
719 
720 /**
721  * gen_true_ecc - This function will generate true ECC value
722  * @ecc_buf: buffer to store ecc code
723  *
724  * This generated true ECC value can be used when correcting
725  * data read from NAND flash memory core
726  */
727 static void gen_true_ecc(u8 *ecc_buf)
728 {
729 	u32 tmp = ecc_buf[0] | (ecc_buf[1] << 16) |
730 		((ecc_buf[2] & 0xF0) << 20) | ((ecc_buf[2] & 0x0F) << 8);
731 
732 	ecc_buf[0] = ~(P64o(tmp) | P64e(tmp) | P32o(tmp) | P32e(tmp) |
733 			P16o(tmp) | P16e(tmp) | P8o(tmp) | P8e(tmp));
734 	ecc_buf[1] = ~(P1024o(tmp) | P1024e(tmp) | P512o(tmp) | P512e(tmp) |
735 			P256o(tmp) | P256e(tmp) | P128o(tmp) | P128e(tmp));
736 	ecc_buf[2] = ~(P4o(tmp) | P4e(tmp) | P2o(tmp) | P2e(tmp) | P1o(tmp) |
737 			P1e(tmp) | P2048o(tmp) | P2048e(tmp));
738 }
739 
740 /**
741  * omap_compare_ecc - Detect (2 bits) and correct (1 bit) error in data
742  * @ecc_data1:  ecc code from nand spare area
743  * @ecc_data2:  ecc code from hardware register obtained from hardware ecc
744  * @page_data:  page data
745  *
746  * This function compares two ECC's and indicates if there is an error.
747  * If the error can be corrected it will be corrected to the buffer.
748  * If there is no error, %0 is returned. If there is an error but it
749  * was corrected, %1 is returned. Otherwise, %-1 is returned.
750  */
751 static int omap_compare_ecc(u8 *ecc_data1,	/* read from NAND memory */
752 			    u8 *ecc_data2,	/* read from register */
753 			    u8 *page_data)
754 {
755 	uint	i;
756 	u8	tmp0_bit[8], tmp1_bit[8], tmp2_bit[8];
757 	u8	comp0_bit[8], comp1_bit[8], comp2_bit[8];
758 	u8	ecc_bit[24];
759 	u8	ecc_sum = 0;
760 	u8	find_bit = 0;
761 	uint	find_byte = 0;
762 	int	isEccFF;
763 
764 	isEccFF = ((*(u32 *)ecc_data1 & 0xFFFFFF) == 0xFFFFFF);
765 
766 	gen_true_ecc(ecc_data1);
767 	gen_true_ecc(ecc_data2);
768 
769 	for (i = 0; i <= 2; i++) {
770 		*(ecc_data1 + i) = ~(*(ecc_data1 + i));
771 		*(ecc_data2 + i) = ~(*(ecc_data2 + i));
772 	}
773 
774 	for (i = 0; i < 8; i++) {
775 		tmp0_bit[i]     = *ecc_data1 % 2;
776 		*ecc_data1	= *ecc_data1 / 2;
777 	}
778 
779 	for (i = 0; i < 8; i++) {
780 		tmp1_bit[i]	 = *(ecc_data1 + 1) % 2;
781 		*(ecc_data1 + 1) = *(ecc_data1 + 1) / 2;
782 	}
783 
784 	for (i = 0; i < 8; i++) {
785 		tmp2_bit[i]	 = *(ecc_data1 + 2) % 2;
786 		*(ecc_data1 + 2) = *(ecc_data1 + 2) / 2;
787 	}
788 
789 	for (i = 0; i < 8; i++) {
790 		comp0_bit[i]     = *ecc_data2 % 2;
791 		*ecc_data2       = *ecc_data2 / 2;
792 	}
793 
794 	for (i = 0; i < 8; i++) {
795 		comp1_bit[i]     = *(ecc_data2 + 1) % 2;
796 		*(ecc_data2 + 1) = *(ecc_data2 + 1) / 2;
797 	}
798 
799 	for (i = 0; i < 8; i++) {
800 		comp2_bit[i]     = *(ecc_data2 + 2) % 2;
801 		*(ecc_data2 + 2) = *(ecc_data2 + 2) / 2;
802 	}
803 
804 	for (i = 0; i < 6; i++)
805 		ecc_bit[i] = tmp2_bit[i + 2] ^ comp2_bit[i + 2];
806 
807 	for (i = 0; i < 8; i++)
808 		ecc_bit[i + 6] = tmp0_bit[i] ^ comp0_bit[i];
809 
810 	for (i = 0; i < 8; i++)
811 		ecc_bit[i + 14] = tmp1_bit[i] ^ comp1_bit[i];
812 
813 	ecc_bit[22] = tmp2_bit[0] ^ comp2_bit[0];
814 	ecc_bit[23] = tmp2_bit[1] ^ comp2_bit[1];
815 
816 	for (i = 0; i < 24; i++)
817 		ecc_sum += ecc_bit[i];
818 
819 	switch (ecc_sum) {
820 	case 0:
821 		/* Not reached because this function is not called if
822 		 *  ECC values are equal
823 		 */
824 		return 0;
825 
826 	case 1:
827 		/* Uncorrectable error */
828 		pr_debug("ECC UNCORRECTED_ERROR 1\n");
829 		return -EBADMSG;
830 
831 	case 11:
832 		/* UN-Correctable error */
833 		pr_debug("ECC UNCORRECTED_ERROR B\n");
834 		return -EBADMSG;
835 
836 	case 12:
837 		/* Correctable error */
838 		find_byte = (ecc_bit[23] << 8) +
839 			    (ecc_bit[21] << 7) +
840 			    (ecc_bit[19] << 6) +
841 			    (ecc_bit[17] << 5) +
842 			    (ecc_bit[15] << 4) +
843 			    (ecc_bit[13] << 3) +
844 			    (ecc_bit[11] << 2) +
845 			    (ecc_bit[9]  << 1) +
846 			    ecc_bit[7];
847 
848 		find_bit = (ecc_bit[5] << 2) + (ecc_bit[3] << 1) + ecc_bit[1];
849 
850 		pr_debug("Correcting single bit ECC error at offset: "
851 				"%d, bit: %d\n", find_byte, find_bit);
852 
853 		page_data[find_byte] ^= (1 << find_bit);
854 
855 		return 1;
856 	default:
857 		if (isEccFF) {
858 			if (ecc_data2[0] == 0 &&
859 			    ecc_data2[1] == 0 &&
860 			    ecc_data2[2] == 0)
861 				return 0;
862 		}
863 		pr_debug("UNCORRECTED_ERROR default\n");
864 		return -EBADMSG;
865 	}
866 }
867 
868 /**
869  * omap_correct_data - Compares the ECC read with HW generated ECC
870  * @chip: NAND chip object
871  * @dat: page data
872  * @read_ecc: ecc read from nand flash
873  * @calc_ecc: ecc read from HW ECC registers
874  *
875  * Compares the ecc read from nand spare area with ECC registers values
876  * and if ECC's mismatched, it will call 'omap_compare_ecc' for error
877  * detection and correction. If there are no errors, %0 is returned. If
878  * there were errors and all of the errors were corrected, the number of
879  * corrected errors is returned. If uncorrectable errors exist, %-1 is
880  * returned.
881  */
882 static int omap_correct_data(struct nand_chip *chip, u_char *dat,
883 			     u_char *read_ecc, u_char *calc_ecc)
884 {
885 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
886 	int blockCnt = 0, i = 0, ret = 0;
887 	int stat = 0;
888 
889 	/* Ex NAND_ECC_HW12_2048 */
890 	if ((info->nand.ecc.mode == NAND_ECC_HW) &&
891 			(info->nand.ecc.size  == 2048))
892 		blockCnt = 4;
893 	else
894 		blockCnt = 1;
895 
896 	for (i = 0; i < blockCnt; i++) {
897 		if (memcmp(read_ecc, calc_ecc, 3) != 0) {
898 			ret = omap_compare_ecc(read_ecc, calc_ecc, dat);
899 			if (ret < 0)
900 				return ret;
901 			/* keep track of the number of corrected errors */
902 			stat += ret;
903 		}
904 		read_ecc += 3;
905 		calc_ecc += 3;
906 		dat      += 512;
907 	}
908 	return stat;
909 }
910 
911 /**
912  * omap_calcuate_ecc - Generate non-inverted ECC bytes.
913  * @chip: NAND chip object
914  * @dat: The pointer to data on which ecc is computed
915  * @ecc_code: The ecc_code buffer
916  *
917  * Using noninverted ECC can be considered ugly since writing a blank
918  * page ie. padding will clear the ECC bytes. This is no problem as long
919  * nobody is trying to write data on the seemingly unused page. Reading
920  * an erased page will produce an ECC mismatch between generated and read
921  * ECC bytes that has to be dealt with separately.
922  */
923 static int omap_calculate_ecc(struct nand_chip *chip, const u_char *dat,
924 			      u_char *ecc_code)
925 {
926 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
927 	u32 val;
928 
929 	val = readl(info->reg.gpmc_ecc_config);
930 	if (((val >> ECC_CONFIG_CS_SHIFT) & CS_MASK) != info->gpmc_cs)
931 		return -EINVAL;
932 
933 	/* read ecc result */
934 	val = readl(info->reg.gpmc_ecc1_result);
935 	*ecc_code++ = val;          /* P128e, ..., P1e */
936 	*ecc_code++ = val >> 16;    /* P128o, ..., P1o */
937 	/* P2048o, P1024o, P512o, P256o, P2048e, P1024e, P512e, P256e */
938 	*ecc_code++ = ((val >> 8) & 0x0f) | ((val >> 20) & 0xf0);
939 
940 	return 0;
941 }
942 
943 /**
944  * omap_enable_hwecc - This function enables the hardware ecc functionality
945  * @mtd: MTD device structure
946  * @mode: Read/Write mode
947  */
948 static void omap_enable_hwecc(struct nand_chip *chip, int mode)
949 {
950 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
951 	unsigned int dev_width = (chip->options & NAND_BUSWIDTH_16) ? 1 : 0;
952 	u32 val;
953 
954 	/* clear ecc and enable bits */
955 	val = ECCCLEAR | ECC1;
956 	writel(val, info->reg.gpmc_ecc_control);
957 
958 	/* program ecc and result sizes */
959 	val = ((((info->nand.ecc.size >> 1) - 1) << ECCSIZE1_SHIFT) |
960 			 ECC1RESULTSIZE);
961 	writel(val, info->reg.gpmc_ecc_size_config);
962 
963 	switch (mode) {
964 	case NAND_ECC_READ:
965 	case NAND_ECC_WRITE:
966 		writel(ECCCLEAR | ECC1, info->reg.gpmc_ecc_control);
967 		break;
968 	case NAND_ECC_READSYN:
969 		writel(ECCCLEAR, info->reg.gpmc_ecc_control);
970 		break;
971 	default:
972 		dev_info(&info->pdev->dev,
973 			"error: unrecognized Mode[%d]!\n", mode);
974 		break;
975 	}
976 
977 	/* (ECC 16 or 8 bit col) | ( CS  )  | ECC Enable */
978 	val = (dev_width << 7) | (info->gpmc_cs << 1) | (0x1);
979 	writel(val, info->reg.gpmc_ecc_config);
980 }
981 
982 /**
983  * omap_wait - wait until the command is done
984  * @this: NAND Chip structure
985  *
986  * Wait function is called during Program and erase operations and
987  * the way it is called from MTD layer, we should wait till the NAND
988  * chip is ready after the programming/erase operation has completed.
989  *
990  * Erase can take up to 400ms and program up to 20ms according to
991  * general NAND and SmartMedia specs
992  */
993 static int omap_wait(struct nand_chip *this)
994 {
995 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(this));
996 	unsigned long timeo = jiffies;
997 	int status, state = this->state;
998 
999 	if (state == FL_ERASING)
1000 		timeo += msecs_to_jiffies(400);
1001 	else
1002 		timeo += msecs_to_jiffies(20);
1003 
1004 	writeb(NAND_CMD_STATUS & 0xFF, info->reg.gpmc_nand_command);
1005 	while (time_before(jiffies, timeo)) {
1006 		status = readb(info->reg.gpmc_nand_data);
1007 		if (status & NAND_STATUS_READY)
1008 			break;
1009 		cond_resched();
1010 	}
1011 
1012 	status = readb(info->reg.gpmc_nand_data);
1013 	return status;
1014 }
1015 
1016 /**
1017  * omap_dev_ready - checks the NAND Ready GPIO line
1018  * @mtd: MTD device structure
1019  *
1020  * Returns true if ready and false if busy.
1021  */
1022 static int omap_dev_ready(struct nand_chip *chip)
1023 {
1024 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
1025 
1026 	return gpiod_get_value(info->ready_gpiod);
1027 }
1028 
1029 /**
1030  * omap_enable_hwecc_bch - Program GPMC to perform BCH ECC calculation
1031  * @mtd: MTD device structure
1032  * @mode: Read/Write mode
1033  *
1034  * When using BCH with SW correction (i.e. no ELM), sector size is set
1035  * to 512 bytes and we use BCH_WRAPMODE_6 wrapping mode
1036  * for both reading and writing with:
1037  * eccsize0 = 0  (no additional protected byte in spare area)
1038  * eccsize1 = 32 (skip 32 nibbles = 16 bytes per sector in spare area)
1039  */
1040 static void __maybe_unused omap_enable_hwecc_bch(struct nand_chip *chip,
1041 						 int mode)
1042 {
1043 	unsigned int bch_type;
1044 	unsigned int dev_width, nsectors;
1045 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
1046 	enum omap_ecc ecc_opt = info->ecc_opt;
1047 	u32 val, wr_mode;
1048 	unsigned int ecc_size1, ecc_size0;
1049 
1050 	/* GPMC configurations for calculating ECC */
1051 	switch (ecc_opt) {
1052 	case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
1053 		bch_type = 0;
1054 		nsectors = 1;
1055 		wr_mode	  = BCH_WRAPMODE_6;
1056 		ecc_size0 = BCH_ECC_SIZE0;
1057 		ecc_size1 = BCH_ECC_SIZE1;
1058 		break;
1059 	case OMAP_ECC_BCH4_CODE_HW:
1060 		bch_type = 0;
1061 		nsectors = chip->ecc.steps;
1062 		if (mode == NAND_ECC_READ) {
1063 			wr_mode	  = BCH_WRAPMODE_1;
1064 			ecc_size0 = BCH4R_ECC_SIZE0;
1065 			ecc_size1 = BCH4R_ECC_SIZE1;
1066 		} else {
1067 			wr_mode   = BCH_WRAPMODE_6;
1068 			ecc_size0 = BCH_ECC_SIZE0;
1069 			ecc_size1 = BCH_ECC_SIZE1;
1070 		}
1071 		break;
1072 	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
1073 		bch_type = 1;
1074 		nsectors = 1;
1075 		wr_mode	  = BCH_WRAPMODE_6;
1076 		ecc_size0 = BCH_ECC_SIZE0;
1077 		ecc_size1 = BCH_ECC_SIZE1;
1078 		break;
1079 	case OMAP_ECC_BCH8_CODE_HW:
1080 		bch_type = 1;
1081 		nsectors = chip->ecc.steps;
1082 		if (mode == NAND_ECC_READ) {
1083 			wr_mode	  = BCH_WRAPMODE_1;
1084 			ecc_size0 = BCH8R_ECC_SIZE0;
1085 			ecc_size1 = BCH8R_ECC_SIZE1;
1086 		} else {
1087 			wr_mode   = BCH_WRAPMODE_6;
1088 			ecc_size0 = BCH_ECC_SIZE0;
1089 			ecc_size1 = BCH_ECC_SIZE1;
1090 		}
1091 		break;
1092 	case OMAP_ECC_BCH16_CODE_HW:
1093 		bch_type = 0x2;
1094 		nsectors = chip->ecc.steps;
1095 		if (mode == NAND_ECC_READ) {
1096 			wr_mode	  = 0x01;
1097 			ecc_size0 = 52; /* ECC bits in nibbles per sector */
1098 			ecc_size1 = 0;  /* non-ECC bits in nibbles per sector */
1099 		} else {
1100 			wr_mode	  = 0x01;
1101 			ecc_size0 = 0;  /* extra bits in nibbles per sector */
1102 			ecc_size1 = 52; /* OOB bits in nibbles per sector */
1103 		}
1104 		break;
1105 	default:
1106 		return;
1107 	}
1108 
1109 	writel(ECC1, info->reg.gpmc_ecc_control);
1110 
1111 	/* Configure ecc size for BCH */
1112 	val = (ecc_size1 << ECCSIZE1_SHIFT) | (ecc_size0 << ECCSIZE0_SHIFT);
1113 	writel(val, info->reg.gpmc_ecc_size_config);
1114 
1115 	dev_width = (chip->options & NAND_BUSWIDTH_16) ? 1 : 0;
1116 
1117 	/* BCH configuration */
1118 	val = ((1                        << 16) | /* enable BCH */
1119 	       (bch_type		 << 12) | /* BCH4/BCH8/BCH16 */
1120 	       (wr_mode                  <<  8) | /* wrap mode */
1121 	       (dev_width                <<  7) | /* bus width */
1122 	       (((nsectors-1) & 0x7)     <<  4) | /* number of sectors */
1123 	       (info->gpmc_cs            <<  1) | /* ECC CS */
1124 	       (0x1));                            /* enable ECC */
1125 
1126 	writel(val, info->reg.gpmc_ecc_config);
1127 
1128 	/* Clear ecc and enable bits */
1129 	writel(ECCCLEAR | ECC1, info->reg.gpmc_ecc_control);
1130 }
1131 
1132 static u8  bch4_polynomial[] = {0x28, 0x13, 0xcc, 0x39, 0x96, 0xac, 0x7f};
1133 static u8  bch8_polynomial[] = {0xef, 0x51, 0x2e, 0x09, 0xed, 0x93, 0x9a, 0xc2,
1134 				0x97, 0x79, 0xe5, 0x24, 0xb5};
1135 
1136 /**
1137  * _omap_calculate_ecc_bch - Generate ECC bytes for one sector
1138  * @mtd:	MTD device structure
1139  * @dat:	The pointer to data on which ecc is computed
1140  * @ecc_code:	The ecc_code buffer
1141  * @i:		The sector number (for a multi sector page)
1142  *
1143  * Support calculating of BCH4/8/16 ECC vectors for one sector
1144  * within a page. Sector number is in @i.
1145  */
1146 static int _omap_calculate_ecc_bch(struct mtd_info *mtd,
1147 				   const u_char *dat, u_char *ecc_calc, int i)
1148 {
1149 	struct omap_nand_info *info = mtd_to_omap(mtd);
1150 	int eccbytes	= info->nand.ecc.bytes;
1151 	struct gpmc_nand_regs	*gpmc_regs = &info->reg;
1152 	u8 *ecc_code;
1153 	unsigned long bch_val1, bch_val2, bch_val3, bch_val4;
1154 	u32 val;
1155 	int j;
1156 
1157 	ecc_code = ecc_calc;
1158 	switch (info->ecc_opt) {
1159 	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
1160 	case OMAP_ECC_BCH8_CODE_HW:
1161 		bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
1162 		bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
1163 		bch_val3 = readl(gpmc_regs->gpmc_bch_result2[i]);
1164 		bch_val4 = readl(gpmc_regs->gpmc_bch_result3[i]);
1165 		*ecc_code++ = (bch_val4 & 0xFF);
1166 		*ecc_code++ = ((bch_val3 >> 24) & 0xFF);
1167 		*ecc_code++ = ((bch_val3 >> 16) & 0xFF);
1168 		*ecc_code++ = ((bch_val3 >> 8) & 0xFF);
1169 		*ecc_code++ = (bch_val3 & 0xFF);
1170 		*ecc_code++ = ((bch_val2 >> 24) & 0xFF);
1171 		*ecc_code++ = ((bch_val2 >> 16) & 0xFF);
1172 		*ecc_code++ = ((bch_val2 >> 8) & 0xFF);
1173 		*ecc_code++ = (bch_val2 & 0xFF);
1174 		*ecc_code++ = ((bch_val1 >> 24) & 0xFF);
1175 		*ecc_code++ = ((bch_val1 >> 16) & 0xFF);
1176 		*ecc_code++ = ((bch_val1 >> 8) & 0xFF);
1177 		*ecc_code++ = (bch_val1 & 0xFF);
1178 		break;
1179 	case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
1180 	case OMAP_ECC_BCH4_CODE_HW:
1181 		bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
1182 		bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
1183 		*ecc_code++ = ((bch_val2 >> 12) & 0xFF);
1184 		*ecc_code++ = ((bch_val2 >> 4) & 0xFF);
1185 		*ecc_code++ = ((bch_val2 & 0xF) << 4) |
1186 			((bch_val1 >> 28) & 0xF);
1187 		*ecc_code++ = ((bch_val1 >> 20) & 0xFF);
1188 		*ecc_code++ = ((bch_val1 >> 12) & 0xFF);
1189 		*ecc_code++ = ((bch_val1 >> 4) & 0xFF);
1190 		*ecc_code++ = ((bch_val1 & 0xF) << 4);
1191 		break;
1192 	case OMAP_ECC_BCH16_CODE_HW:
1193 		val = readl(gpmc_regs->gpmc_bch_result6[i]);
1194 		ecc_code[0]  = ((val >>  8) & 0xFF);
1195 		ecc_code[1]  = ((val >>  0) & 0xFF);
1196 		val = readl(gpmc_regs->gpmc_bch_result5[i]);
1197 		ecc_code[2]  = ((val >> 24) & 0xFF);
1198 		ecc_code[3]  = ((val >> 16) & 0xFF);
1199 		ecc_code[4]  = ((val >>  8) & 0xFF);
1200 		ecc_code[5]  = ((val >>  0) & 0xFF);
1201 		val = readl(gpmc_regs->gpmc_bch_result4[i]);
1202 		ecc_code[6]  = ((val >> 24) & 0xFF);
1203 		ecc_code[7]  = ((val >> 16) & 0xFF);
1204 		ecc_code[8]  = ((val >>  8) & 0xFF);
1205 		ecc_code[9]  = ((val >>  0) & 0xFF);
1206 		val = readl(gpmc_regs->gpmc_bch_result3[i]);
1207 		ecc_code[10] = ((val >> 24) & 0xFF);
1208 		ecc_code[11] = ((val >> 16) & 0xFF);
1209 		ecc_code[12] = ((val >>  8) & 0xFF);
1210 		ecc_code[13] = ((val >>  0) & 0xFF);
1211 		val = readl(gpmc_regs->gpmc_bch_result2[i]);
1212 		ecc_code[14] = ((val >> 24) & 0xFF);
1213 		ecc_code[15] = ((val >> 16) & 0xFF);
1214 		ecc_code[16] = ((val >>  8) & 0xFF);
1215 		ecc_code[17] = ((val >>  0) & 0xFF);
1216 		val = readl(gpmc_regs->gpmc_bch_result1[i]);
1217 		ecc_code[18] = ((val >> 24) & 0xFF);
1218 		ecc_code[19] = ((val >> 16) & 0xFF);
1219 		ecc_code[20] = ((val >>  8) & 0xFF);
1220 		ecc_code[21] = ((val >>  0) & 0xFF);
1221 		val = readl(gpmc_regs->gpmc_bch_result0[i]);
1222 		ecc_code[22] = ((val >> 24) & 0xFF);
1223 		ecc_code[23] = ((val >> 16) & 0xFF);
1224 		ecc_code[24] = ((val >>  8) & 0xFF);
1225 		ecc_code[25] = ((val >>  0) & 0xFF);
1226 		break;
1227 	default:
1228 		return -EINVAL;
1229 	}
1230 
1231 	/* ECC scheme specific syndrome customizations */
1232 	switch (info->ecc_opt) {
1233 	case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
1234 		/* Add constant polynomial to remainder, so that
1235 		 * ECC of blank pages results in 0x0 on reading back
1236 		 */
1237 		for (j = 0; j < eccbytes; j++)
1238 			ecc_calc[j] ^= bch4_polynomial[j];
1239 		break;
1240 	case OMAP_ECC_BCH4_CODE_HW:
1241 		/* Set  8th ECC byte as 0x0 for ROM compatibility */
1242 		ecc_calc[eccbytes - 1] = 0x0;
1243 		break;
1244 	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
1245 		/* Add constant polynomial to remainder, so that
1246 		 * ECC of blank pages results in 0x0 on reading back
1247 		 */
1248 		for (j = 0; j < eccbytes; j++)
1249 			ecc_calc[j] ^= bch8_polynomial[j];
1250 		break;
1251 	case OMAP_ECC_BCH8_CODE_HW:
1252 		/* Set 14th ECC byte as 0x0 for ROM compatibility */
1253 		ecc_calc[eccbytes - 1] = 0x0;
1254 		break;
1255 	case OMAP_ECC_BCH16_CODE_HW:
1256 		break;
1257 	default:
1258 		return -EINVAL;
1259 	}
1260 
1261 	return 0;
1262 }
1263 
1264 /**
1265  * omap_calculate_ecc_bch_sw - ECC generator for sector for SW based correction
1266  * @chip:	NAND chip object
1267  * @dat:	The pointer to data on which ecc is computed
1268  * @ecc_code:	The ecc_code buffer
1269  *
1270  * Support calculating of BCH4/8/16 ECC vectors for one sector. This is used
1271  * when SW based correction is required as ECC is required for one sector
1272  * at a time.
1273  */
1274 static int omap_calculate_ecc_bch_sw(struct nand_chip *chip,
1275 				     const u_char *dat, u_char *ecc_calc)
1276 {
1277 	return _omap_calculate_ecc_bch(nand_to_mtd(chip), dat, ecc_calc, 0);
1278 }
1279 
1280 /**
1281  * omap_calculate_ecc_bch_multi - Generate ECC for multiple sectors
1282  * @mtd:	MTD device structure
1283  * @dat:	The pointer to data on which ecc is computed
1284  * @ecc_code:	The ecc_code buffer
1285  *
1286  * Support calculating of BCH4/8/16 ecc vectors for the entire page in one go.
1287  */
1288 static int omap_calculate_ecc_bch_multi(struct mtd_info *mtd,
1289 					const u_char *dat, u_char *ecc_calc)
1290 {
1291 	struct omap_nand_info *info = mtd_to_omap(mtd);
1292 	int eccbytes = info->nand.ecc.bytes;
1293 	unsigned long nsectors;
1294 	int i, ret;
1295 
1296 	nsectors = ((readl(info->reg.gpmc_ecc_config) >> 4) & 0x7) + 1;
1297 	for (i = 0; i < nsectors; i++) {
1298 		ret = _omap_calculate_ecc_bch(mtd, dat, ecc_calc, i);
1299 		if (ret)
1300 			return ret;
1301 
1302 		ecc_calc += eccbytes;
1303 	}
1304 
1305 	return 0;
1306 }
1307 
1308 /**
1309  * erased_sector_bitflips - count bit flips
1310  * @data:	data sector buffer
1311  * @oob:	oob buffer
1312  * @info:	omap_nand_info
1313  *
1314  * Check the bit flips in erased page falls below correctable level.
1315  * If falls below, report the page as erased with correctable bit
1316  * flip, else report as uncorrectable page.
1317  */
1318 static int erased_sector_bitflips(u_char *data, u_char *oob,
1319 		struct omap_nand_info *info)
1320 {
1321 	int flip_bits = 0, i;
1322 
1323 	for (i = 0; i < info->nand.ecc.size; i++) {
1324 		flip_bits += hweight8(~data[i]);
1325 		if (flip_bits > info->nand.ecc.strength)
1326 			return 0;
1327 	}
1328 
1329 	for (i = 0; i < info->nand.ecc.bytes - 1; i++) {
1330 		flip_bits += hweight8(~oob[i]);
1331 		if (flip_bits > info->nand.ecc.strength)
1332 			return 0;
1333 	}
1334 
1335 	/*
1336 	 * Bit flips falls in correctable level.
1337 	 * Fill data area with 0xFF
1338 	 */
1339 	if (flip_bits) {
1340 		memset(data, 0xFF, info->nand.ecc.size);
1341 		memset(oob, 0xFF, info->nand.ecc.bytes);
1342 	}
1343 
1344 	return flip_bits;
1345 }
1346 
1347 /**
1348  * omap_elm_correct_data - corrects page data area in case error reported
1349  * @chip:	NAND chip object
1350  * @data:	page data
1351  * @read_ecc:	ecc read from nand flash
1352  * @calc_ecc:	ecc read from HW ECC registers
1353  *
1354  * Calculated ecc vector reported as zero in case of non-error pages.
1355  * In case of non-zero ecc vector, first filter out erased-pages, and
1356  * then process data via ELM to detect bit-flips.
1357  */
1358 static int omap_elm_correct_data(struct nand_chip *chip, u_char *data,
1359 				 u_char *read_ecc, u_char *calc_ecc)
1360 {
1361 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
1362 	struct nand_ecc_ctrl *ecc = &info->nand.ecc;
1363 	int eccsteps = info->nand.ecc.steps;
1364 	int i , j, stat = 0;
1365 	int eccflag, actual_eccbytes;
1366 	struct elm_errorvec err_vec[ERROR_VECTOR_MAX];
1367 	u_char *ecc_vec = calc_ecc;
1368 	u_char *spare_ecc = read_ecc;
1369 	u_char *erased_ecc_vec;
1370 	u_char *buf;
1371 	int bitflip_count;
1372 	bool is_error_reported = false;
1373 	u32 bit_pos, byte_pos, error_max, pos;
1374 	int err;
1375 
1376 	switch (info->ecc_opt) {
1377 	case OMAP_ECC_BCH4_CODE_HW:
1378 		/* omit  7th ECC byte reserved for ROM code compatibility */
1379 		actual_eccbytes = ecc->bytes - 1;
1380 		erased_ecc_vec = bch4_vector;
1381 		break;
1382 	case OMAP_ECC_BCH8_CODE_HW:
1383 		/* omit 14th ECC byte reserved for ROM code compatibility */
1384 		actual_eccbytes = ecc->bytes - 1;
1385 		erased_ecc_vec = bch8_vector;
1386 		break;
1387 	case OMAP_ECC_BCH16_CODE_HW:
1388 		actual_eccbytes = ecc->bytes;
1389 		erased_ecc_vec = bch16_vector;
1390 		break;
1391 	default:
1392 		dev_err(&info->pdev->dev, "invalid driver configuration\n");
1393 		return -EINVAL;
1394 	}
1395 
1396 	/* Initialize elm error vector to zero */
1397 	memset(err_vec, 0, sizeof(err_vec));
1398 
1399 	for (i = 0; i < eccsteps ; i++) {
1400 		eccflag = 0;	/* initialize eccflag */
1401 
1402 		/*
1403 		 * Check any error reported,
1404 		 * In case of error, non zero ecc reported.
1405 		 */
1406 		for (j = 0; j < actual_eccbytes; j++) {
1407 			if (calc_ecc[j] != 0) {
1408 				eccflag = 1; /* non zero ecc, error present */
1409 				break;
1410 			}
1411 		}
1412 
1413 		if (eccflag == 1) {
1414 			if (memcmp(calc_ecc, erased_ecc_vec,
1415 						actual_eccbytes) == 0) {
1416 				/*
1417 				 * calc_ecc[] matches pattern for ECC(all 0xff)
1418 				 * so this is definitely an erased-page
1419 				 */
1420 			} else {
1421 				buf = &data[info->nand.ecc.size * i];
1422 				/*
1423 				 * count number of 0-bits in read_buf.
1424 				 * This check can be removed once a similar
1425 				 * check is introduced in generic NAND driver
1426 				 */
1427 				bitflip_count = erased_sector_bitflips(
1428 						buf, read_ecc, info);
1429 				if (bitflip_count) {
1430 					/*
1431 					 * number of 0-bits within ECC limits
1432 					 * So this may be an erased-page
1433 					 */
1434 					stat += bitflip_count;
1435 				} else {
1436 					/*
1437 					 * Too many 0-bits. It may be a
1438 					 * - programmed-page, OR
1439 					 * - erased-page with many bit-flips
1440 					 * So this page requires check by ELM
1441 					 */
1442 					err_vec[i].error_reported = true;
1443 					is_error_reported = true;
1444 				}
1445 			}
1446 		}
1447 
1448 		/* Update the ecc vector */
1449 		calc_ecc += ecc->bytes;
1450 		read_ecc += ecc->bytes;
1451 	}
1452 
1453 	/* Check if any error reported */
1454 	if (!is_error_reported)
1455 		return stat;
1456 
1457 	/* Decode BCH error using ELM module */
1458 	elm_decode_bch_error_page(info->elm_dev, ecc_vec, err_vec);
1459 
1460 	err = 0;
1461 	for (i = 0; i < eccsteps; i++) {
1462 		if (err_vec[i].error_uncorrectable) {
1463 			dev_err(&info->pdev->dev,
1464 				"uncorrectable bit-flips found\n");
1465 			err = -EBADMSG;
1466 		} else if (err_vec[i].error_reported) {
1467 			for (j = 0; j < err_vec[i].error_count; j++) {
1468 				switch (info->ecc_opt) {
1469 				case OMAP_ECC_BCH4_CODE_HW:
1470 					/* Add 4 bits to take care of padding */
1471 					pos = err_vec[i].error_loc[j] +
1472 						BCH4_BIT_PAD;
1473 					break;
1474 				case OMAP_ECC_BCH8_CODE_HW:
1475 				case OMAP_ECC_BCH16_CODE_HW:
1476 					pos = err_vec[i].error_loc[j];
1477 					break;
1478 				default:
1479 					return -EINVAL;
1480 				}
1481 				error_max = (ecc->size + actual_eccbytes) * 8;
1482 				/* Calculate bit position of error */
1483 				bit_pos = pos % 8;
1484 
1485 				/* Calculate byte position of error */
1486 				byte_pos = (error_max - pos - 1) / 8;
1487 
1488 				if (pos < error_max) {
1489 					if (byte_pos < 512) {
1490 						pr_debug("bitflip@dat[%d]=%x\n",
1491 						     byte_pos, data[byte_pos]);
1492 						data[byte_pos] ^= 1 << bit_pos;
1493 					} else {
1494 						pr_debug("bitflip@oob[%d]=%x\n",
1495 							(byte_pos - 512),
1496 						     spare_ecc[byte_pos - 512]);
1497 						spare_ecc[byte_pos - 512] ^=
1498 							1 << bit_pos;
1499 					}
1500 				} else {
1501 					dev_err(&info->pdev->dev,
1502 						"invalid bit-flip @ %d:%d\n",
1503 						byte_pos, bit_pos);
1504 					err = -EBADMSG;
1505 				}
1506 			}
1507 		}
1508 
1509 		/* Update number of correctable errors */
1510 		stat += err_vec[i].error_count;
1511 
1512 		/* Update page data with sector size */
1513 		data += ecc->size;
1514 		spare_ecc += ecc->bytes;
1515 	}
1516 
1517 	return (err) ? err : stat;
1518 }
1519 
1520 /**
1521  * omap_write_page_bch - BCH ecc based write page function for entire page
1522  * @chip:		nand chip info structure
1523  * @buf:		data buffer
1524  * @oob_required:	must write chip->oob_poi to OOB
1525  * @page:		page
1526  *
1527  * Custom write page method evolved to support multi sector writing in one shot
1528  */
1529 static int omap_write_page_bch(struct nand_chip *chip, const uint8_t *buf,
1530 			       int oob_required, int page)
1531 {
1532 	struct mtd_info *mtd = nand_to_mtd(chip);
1533 	int ret;
1534 	uint8_t *ecc_calc = chip->ecc.calc_buf;
1535 
1536 	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
1537 
1538 	/* Enable GPMC ecc engine */
1539 	chip->ecc.hwctl(chip, NAND_ECC_WRITE);
1540 
1541 	/* Write data */
1542 	chip->legacy.write_buf(chip, buf, mtd->writesize);
1543 
1544 	/* Update ecc vector from GPMC result registers */
1545 	omap_calculate_ecc_bch_multi(mtd, buf, &ecc_calc[0]);
1546 
1547 	ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
1548 					 chip->ecc.total);
1549 	if (ret)
1550 		return ret;
1551 
1552 	/* Write ecc vector to OOB area */
1553 	chip->legacy.write_buf(chip, chip->oob_poi, mtd->oobsize);
1554 
1555 	return nand_prog_page_end_op(chip);
1556 }
1557 
1558 /**
1559  * omap_write_subpage_bch - BCH hardware ECC based subpage write
1560  * @chip:	nand chip info structure
1561  * @offset:	column address of subpage within the page
1562  * @data_len:	data length
1563  * @buf:	data buffer
1564  * @oob_required: must write chip->oob_poi to OOB
1565  * @page: page number to write
1566  *
1567  * OMAP optimized subpage write method.
1568  */
1569 static int omap_write_subpage_bch(struct nand_chip *chip, u32 offset,
1570 				  u32 data_len, const u8 *buf,
1571 				  int oob_required, int page)
1572 {
1573 	struct mtd_info *mtd = nand_to_mtd(chip);
1574 	u8 *ecc_calc = chip->ecc.calc_buf;
1575 	int ecc_size      = chip->ecc.size;
1576 	int ecc_bytes     = chip->ecc.bytes;
1577 	int ecc_steps     = chip->ecc.steps;
1578 	u32 start_step = offset / ecc_size;
1579 	u32 end_step   = (offset + data_len - 1) / ecc_size;
1580 	int step, ret = 0;
1581 
1582 	/*
1583 	 * Write entire page at one go as it would be optimal
1584 	 * as ECC is calculated by hardware.
1585 	 * ECC is calculated for all subpages but we choose
1586 	 * only what we want.
1587 	 */
1588 	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
1589 
1590 	/* Enable GPMC ECC engine */
1591 	chip->ecc.hwctl(chip, NAND_ECC_WRITE);
1592 
1593 	/* Write data */
1594 	chip->legacy.write_buf(chip, buf, mtd->writesize);
1595 
1596 	for (step = 0; step < ecc_steps; step++) {
1597 		/* mask ECC of un-touched subpages by padding 0xFF */
1598 		if (step < start_step || step > end_step)
1599 			memset(ecc_calc, 0xff, ecc_bytes);
1600 		else
1601 			ret = _omap_calculate_ecc_bch(mtd, buf, ecc_calc, step);
1602 
1603 		if (ret)
1604 			return ret;
1605 
1606 		buf += ecc_size;
1607 		ecc_calc += ecc_bytes;
1608 	}
1609 
1610 	/* copy calculated ECC for whole page to chip->buffer->oob */
1611 	/* this include masked-value(0xFF) for unwritten subpages */
1612 	ecc_calc = chip->ecc.calc_buf;
1613 	ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
1614 					 chip->ecc.total);
1615 	if (ret)
1616 		return ret;
1617 
1618 	/* write OOB buffer to NAND device */
1619 	chip->legacy.write_buf(chip, chip->oob_poi, mtd->oobsize);
1620 
1621 	return nand_prog_page_end_op(chip);
1622 }
1623 
1624 /**
1625  * omap_read_page_bch - BCH ecc based page read function for entire page
1626  * @chip:		nand chip info structure
1627  * @buf:		buffer to store read data
1628  * @oob_required:	caller requires OOB data read to chip->oob_poi
1629  * @page:		page number to read
1630  *
1631  * For BCH ecc scheme, GPMC used for syndrome calculation and ELM module
1632  * used for error correction.
1633  * Custom method evolved to support ELM error correction & multi sector
1634  * reading. On reading page data area is read along with OOB data with
1635  * ecc engine enabled. ecc vector updated after read of OOB data.
1636  * For non error pages ecc vector reported as zero.
1637  */
1638 static int omap_read_page_bch(struct nand_chip *chip, uint8_t *buf,
1639 			      int oob_required, int page)
1640 {
1641 	struct mtd_info *mtd = nand_to_mtd(chip);
1642 	uint8_t *ecc_calc = chip->ecc.calc_buf;
1643 	uint8_t *ecc_code = chip->ecc.code_buf;
1644 	int stat, ret;
1645 	unsigned int max_bitflips = 0;
1646 
1647 	nand_read_page_op(chip, page, 0, NULL, 0);
1648 
1649 	/* Enable GPMC ecc engine */
1650 	chip->ecc.hwctl(chip, NAND_ECC_READ);
1651 
1652 	/* Read data */
1653 	chip->legacy.read_buf(chip, buf, mtd->writesize);
1654 
1655 	/* Read oob bytes */
1656 	nand_change_read_column_op(chip,
1657 				   mtd->writesize + BADBLOCK_MARKER_LENGTH,
1658 				   chip->oob_poi + BADBLOCK_MARKER_LENGTH,
1659 				   chip->ecc.total, false);
1660 
1661 	/* Calculate ecc bytes */
1662 	omap_calculate_ecc_bch_multi(mtd, buf, ecc_calc);
1663 
1664 	ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
1665 					 chip->ecc.total);
1666 	if (ret)
1667 		return ret;
1668 
1669 	stat = chip->ecc.correct(chip, buf, ecc_code, ecc_calc);
1670 
1671 	if (stat < 0) {
1672 		mtd->ecc_stats.failed++;
1673 	} else {
1674 		mtd->ecc_stats.corrected += stat;
1675 		max_bitflips = max_t(unsigned int, max_bitflips, stat);
1676 	}
1677 
1678 	return max_bitflips;
1679 }
1680 
1681 /**
1682  * is_elm_present - checks for presence of ELM module by scanning DT nodes
1683  * @omap_nand_info: NAND device structure containing platform data
1684  */
1685 static bool is_elm_present(struct omap_nand_info *info,
1686 			   struct device_node *elm_node)
1687 {
1688 	struct platform_device *pdev;
1689 
1690 	/* check whether elm-id is passed via DT */
1691 	if (!elm_node) {
1692 		dev_err(&info->pdev->dev, "ELM devicetree node not found\n");
1693 		return false;
1694 	}
1695 	pdev = of_find_device_by_node(elm_node);
1696 	/* check whether ELM device is registered */
1697 	if (!pdev) {
1698 		dev_err(&info->pdev->dev, "ELM device not found\n");
1699 		return false;
1700 	}
1701 	/* ELM module available, now configure it */
1702 	info->elm_dev = &pdev->dev;
1703 	return true;
1704 }
1705 
1706 static bool omap2_nand_ecc_check(struct omap_nand_info *info)
1707 {
1708 	bool ecc_needs_bch, ecc_needs_omap_bch, ecc_needs_elm;
1709 
1710 	switch (info->ecc_opt) {
1711 	case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
1712 	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
1713 		ecc_needs_omap_bch = false;
1714 		ecc_needs_bch = true;
1715 		ecc_needs_elm = false;
1716 		break;
1717 	case OMAP_ECC_BCH4_CODE_HW:
1718 	case OMAP_ECC_BCH8_CODE_HW:
1719 	case OMAP_ECC_BCH16_CODE_HW:
1720 		ecc_needs_omap_bch = true;
1721 		ecc_needs_bch = false;
1722 		ecc_needs_elm = true;
1723 		break;
1724 	default:
1725 		ecc_needs_omap_bch = false;
1726 		ecc_needs_bch = false;
1727 		ecc_needs_elm = false;
1728 		break;
1729 	}
1730 
1731 	if (ecc_needs_bch && !IS_ENABLED(CONFIG_MTD_NAND_ECC_BCH)) {
1732 		dev_err(&info->pdev->dev,
1733 			"CONFIG_MTD_NAND_ECC_BCH not enabled\n");
1734 		return false;
1735 	}
1736 	if (ecc_needs_omap_bch && !IS_ENABLED(CONFIG_MTD_NAND_OMAP_BCH)) {
1737 		dev_err(&info->pdev->dev,
1738 			"CONFIG_MTD_NAND_OMAP_BCH not enabled\n");
1739 		return false;
1740 	}
1741 	if (ecc_needs_elm && !is_elm_present(info, info->elm_of_node)) {
1742 		dev_err(&info->pdev->dev, "ELM not available\n");
1743 		return false;
1744 	}
1745 
1746 	return true;
1747 }
1748 
1749 static const char * const nand_xfer_types[] = {
1750 	[NAND_OMAP_PREFETCH_POLLED] = "prefetch-polled",
1751 	[NAND_OMAP_POLLED] = "polled",
1752 	[NAND_OMAP_PREFETCH_DMA] = "prefetch-dma",
1753 	[NAND_OMAP_PREFETCH_IRQ] = "prefetch-irq",
1754 };
1755 
1756 static int omap_get_dt_info(struct device *dev, struct omap_nand_info *info)
1757 {
1758 	struct device_node *child = dev->of_node;
1759 	int i;
1760 	const char *s;
1761 	u32 cs;
1762 
1763 	if (of_property_read_u32(child, "reg", &cs) < 0) {
1764 		dev_err(dev, "reg not found in DT\n");
1765 		return -EINVAL;
1766 	}
1767 
1768 	info->gpmc_cs = cs;
1769 
1770 	/* detect availability of ELM module. Won't be present pre-OMAP4 */
1771 	info->elm_of_node = of_parse_phandle(child, "ti,elm-id", 0);
1772 	if (!info->elm_of_node) {
1773 		info->elm_of_node = of_parse_phandle(child, "elm_id", 0);
1774 		if (!info->elm_of_node)
1775 			dev_dbg(dev, "ti,elm-id not in DT\n");
1776 	}
1777 
1778 	/* select ecc-scheme for NAND */
1779 	if (of_property_read_string(child, "ti,nand-ecc-opt", &s)) {
1780 		dev_err(dev, "ti,nand-ecc-opt not found\n");
1781 		return -EINVAL;
1782 	}
1783 
1784 	if (!strcmp(s, "sw")) {
1785 		info->ecc_opt = OMAP_ECC_HAM1_CODE_SW;
1786 	} else if (!strcmp(s, "ham1") ||
1787 		   !strcmp(s, "hw") || !strcmp(s, "hw-romcode")) {
1788 		info->ecc_opt =	OMAP_ECC_HAM1_CODE_HW;
1789 	} else if (!strcmp(s, "bch4")) {
1790 		if (info->elm_of_node)
1791 			info->ecc_opt = OMAP_ECC_BCH4_CODE_HW;
1792 		else
1793 			info->ecc_opt = OMAP_ECC_BCH4_CODE_HW_DETECTION_SW;
1794 	} else if (!strcmp(s, "bch8")) {
1795 		if (info->elm_of_node)
1796 			info->ecc_opt = OMAP_ECC_BCH8_CODE_HW;
1797 		else
1798 			info->ecc_opt = OMAP_ECC_BCH8_CODE_HW_DETECTION_SW;
1799 	} else if (!strcmp(s, "bch16")) {
1800 		info->ecc_opt =	OMAP_ECC_BCH16_CODE_HW;
1801 	} else {
1802 		dev_err(dev, "unrecognized value for ti,nand-ecc-opt\n");
1803 		return -EINVAL;
1804 	}
1805 
1806 	/* select data transfer mode */
1807 	if (!of_property_read_string(child, "ti,nand-xfer-type", &s)) {
1808 		for (i = 0; i < ARRAY_SIZE(nand_xfer_types); i++) {
1809 			if (!strcasecmp(s, nand_xfer_types[i])) {
1810 				info->xfer_type = i;
1811 				return 0;
1812 			}
1813 		}
1814 
1815 		dev_err(dev, "unrecognized value for ti,nand-xfer-type\n");
1816 		return -EINVAL;
1817 	}
1818 
1819 	return 0;
1820 }
1821 
1822 static int omap_ooblayout_ecc(struct mtd_info *mtd, int section,
1823 			      struct mtd_oob_region *oobregion)
1824 {
1825 	struct omap_nand_info *info = mtd_to_omap(mtd);
1826 	struct nand_chip *chip = &info->nand;
1827 	int off = BADBLOCK_MARKER_LENGTH;
1828 
1829 	if (info->ecc_opt == OMAP_ECC_HAM1_CODE_HW &&
1830 	    !(chip->options & NAND_BUSWIDTH_16))
1831 		off = 1;
1832 
1833 	if (section)
1834 		return -ERANGE;
1835 
1836 	oobregion->offset = off;
1837 	oobregion->length = chip->ecc.total;
1838 
1839 	return 0;
1840 }
1841 
1842 static int omap_ooblayout_free(struct mtd_info *mtd, int section,
1843 			       struct mtd_oob_region *oobregion)
1844 {
1845 	struct omap_nand_info *info = mtd_to_omap(mtd);
1846 	struct nand_chip *chip = &info->nand;
1847 	int off = BADBLOCK_MARKER_LENGTH;
1848 
1849 	if (info->ecc_opt == OMAP_ECC_HAM1_CODE_HW &&
1850 	    !(chip->options & NAND_BUSWIDTH_16))
1851 		off = 1;
1852 
1853 	if (section)
1854 		return -ERANGE;
1855 
1856 	off += chip->ecc.total;
1857 	if (off >= mtd->oobsize)
1858 		return -ERANGE;
1859 
1860 	oobregion->offset = off;
1861 	oobregion->length = mtd->oobsize - off;
1862 
1863 	return 0;
1864 }
1865 
1866 static const struct mtd_ooblayout_ops omap_ooblayout_ops = {
1867 	.ecc = omap_ooblayout_ecc,
1868 	.free = omap_ooblayout_free,
1869 };
1870 
1871 static int omap_sw_ooblayout_ecc(struct mtd_info *mtd, int section,
1872 				 struct mtd_oob_region *oobregion)
1873 {
1874 	struct nand_chip *chip = mtd_to_nand(mtd);
1875 	int off = BADBLOCK_MARKER_LENGTH;
1876 
1877 	if (section >= chip->ecc.steps)
1878 		return -ERANGE;
1879 
1880 	/*
1881 	 * When SW correction is employed, one OMAP specific marker byte is
1882 	 * reserved after each ECC step.
1883 	 */
1884 	oobregion->offset = off + (section * (chip->ecc.bytes + 1));
1885 	oobregion->length = chip->ecc.bytes;
1886 
1887 	return 0;
1888 }
1889 
1890 static int omap_sw_ooblayout_free(struct mtd_info *mtd, int section,
1891 				  struct mtd_oob_region *oobregion)
1892 {
1893 	struct nand_chip *chip = mtd_to_nand(mtd);
1894 	int off = BADBLOCK_MARKER_LENGTH;
1895 
1896 	if (section)
1897 		return -ERANGE;
1898 
1899 	/*
1900 	 * When SW correction is employed, one OMAP specific marker byte is
1901 	 * reserved after each ECC step.
1902 	 */
1903 	off += ((chip->ecc.bytes + 1) * chip->ecc.steps);
1904 	if (off >= mtd->oobsize)
1905 		return -ERANGE;
1906 
1907 	oobregion->offset = off;
1908 	oobregion->length = mtd->oobsize - off;
1909 
1910 	return 0;
1911 }
1912 
1913 static const struct mtd_ooblayout_ops omap_sw_ooblayout_ops = {
1914 	.ecc = omap_sw_ooblayout_ecc,
1915 	.free = omap_sw_ooblayout_free,
1916 };
1917 
1918 static int omap_nand_attach_chip(struct nand_chip *chip)
1919 {
1920 	struct mtd_info *mtd = nand_to_mtd(chip);
1921 	struct omap_nand_info *info = mtd_to_omap(mtd);
1922 	struct device *dev = &info->pdev->dev;
1923 	int min_oobbytes = BADBLOCK_MARKER_LENGTH;
1924 	int oobbytes_per_step;
1925 	dma_cap_mask_t mask;
1926 	int err;
1927 
1928 	if (chip->bbt_options & NAND_BBT_USE_FLASH)
1929 		chip->bbt_options |= NAND_BBT_NO_OOB;
1930 	else
1931 		chip->options |= NAND_SKIP_BBTSCAN;
1932 
1933 	/* Re-populate low-level callbacks based on xfer modes */
1934 	switch (info->xfer_type) {
1935 	case NAND_OMAP_PREFETCH_POLLED:
1936 		chip->legacy.read_buf = omap_read_buf_pref;
1937 		chip->legacy.write_buf = omap_write_buf_pref;
1938 		break;
1939 
1940 	case NAND_OMAP_POLLED:
1941 		/* Use nand_base defaults for {read,write}_buf */
1942 		break;
1943 
1944 	case NAND_OMAP_PREFETCH_DMA:
1945 		dma_cap_zero(mask);
1946 		dma_cap_set(DMA_SLAVE, mask);
1947 		info->dma = dma_request_chan(dev, "rxtx");
1948 
1949 		if (IS_ERR(info->dma)) {
1950 			dev_err(dev, "DMA engine request failed\n");
1951 			return PTR_ERR(info->dma);
1952 		} else {
1953 			struct dma_slave_config cfg;
1954 
1955 			memset(&cfg, 0, sizeof(cfg));
1956 			cfg.src_addr = info->phys_base;
1957 			cfg.dst_addr = info->phys_base;
1958 			cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
1959 			cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
1960 			cfg.src_maxburst = 16;
1961 			cfg.dst_maxburst = 16;
1962 			err = dmaengine_slave_config(info->dma, &cfg);
1963 			if (err) {
1964 				dev_err(dev,
1965 					"DMA engine slave config failed: %d\n",
1966 					err);
1967 				return err;
1968 			}
1969 			chip->legacy.read_buf = omap_read_buf_dma_pref;
1970 			chip->legacy.write_buf = omap_write_buf_dma_pref;
1971 		}
1972 		break;
1973 
1974 	case NAND_OMAP_PREFETCH_IRQ:
1975 		info->gpmc_irq_fifo = platform_get_irq(info->pdev, 0);
1976 		if (info->gpmc_irq_fifo <= 0) {
1977 			dev_err(dev, "Error getting fifo IRQ\n");
1978 			return -ENODEV;
1979 		}
1980 		err = devm_request_irq(dev, info->gpmc_irq_fifo,
1981 				       omap_nand_irq, IRQF_SHARED,
1982 				       "gpmc-nand-fifo", info);
1983 		if (err) {
1984 			dev_err(dev, "Requesting IRQ %d, error %d\n",
1985 				info->gpmc_irq_fifo, err);
1986 			info->gpmc_irq_fifo = 0;
1987 			return err;
1988 		}
1989 
1990 		info->gpmc_irq_count = platform_get_irq(info->pdev, 1);
1991 		if (info->gpmc_irq_count <= 0) {
1992 			dev_err(dev, "Error getting IRQ count\n");
1993 			return -ENODEV;
1994 		}
1995 		err = devm_request_irq(dev, info->gpmc_irq_count,
1996 				       omap_nand_irq, IRQF_SHARED,
1997 				       "gpmc-nand-count", info);
1998 		if (err) {
1999 			dev_err(dev, "Requesting IRQ %d, error %d\n",
2000 				info->gpmc_irq_count, err);
2001 			info->gpmc_irq_count = 0;
2002 			return err;
2003 		}
2004 
2005 		chip->legacy.read_buf = omap_read_buf_irq_pref;
2006 		chip->legacy.write_buf = omap_write_buf_irq_pref;
2007 
2008 		break;
2009 
2010 	default:
2011 		dev_err(dev, "xfer_type %d not supported!\n", info->xfer_type);
2012 		return -EINVAL;
2013 	}
2014 
2015 	if (!omap2_nand_ecc_check(info))
2016 		return -EINVAL;
2017 
2018 	/*
2019 	 * Bail out earlier to let NAND_ECC_SOFT code create its own
2020 	 * ooblayout instead of using ours.
2021 	 */
2022 	if (info->ecc_opt == OMAP_ECC_HAM1_CODE_SW) {
2023 		chip->ecc.mode = NAND_ECC_SOFT;
2024 		chip->ecc.algo = NAND_ECC_HAMMING;
2025 		return 0;
2026 	}
2027 
2028 	/* Populate MTD interface based on ECC scheme */
2029 	switch (info->ecc_opt) {
2030 	case OMAP_ECC_HAM1_CODE_HW:
2031 		dev_info(dev, "nand: using OMAP_ECC_HAM1_CODE_HW\n");
2032 		chip->ecc.mode		= NAND_ECC_HW;
2033 		chip->ecc.bytes		= 3;
2034 		chip->ecc.size		= 512;
2035 		chip->ecc.strength	= 1;
2036 		chip->ecc.calculate	= omap_calculate_ecc;
2037 		chip->ecc.hwctl		= omap_enable_hwecc;
2038 		chip->ecc.correct	= omap_correct_data;
2039 		mtd_set_ooblayout(mtd, &omap_ooblayout_ops);
2040 		oobbytes_per_step	= chip->ecc.bytes;
2041 
2042 		if (!(chip->options & NAND_BUSWIDTH_16))
2043 			min_oobbytes	= 1;
2044 
2045 		break;
2046 
2047 	case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
2048 		pr_info("nand: using OMAP_ECC_BCH4_CODE_HW_DETECTION_SW\n");
2049 		chip->ecc.mode		= NAND_ECC_HW;
2050 		chip->ecc.size		= 512;
2051 		chip->ecc.bytes		= 7;
2052 		chip->ecc.strength	= 4;
2053 		chip->ecc.hwctl		= omap_enable_hwecc_bch;
2054 		chip->ecc.correct	= nand_bch_correct_data;
2055 		chip->ecc.calculate	= omap_calculate_ecc_bch_sw;
2056 		mtd_set_ooblayout(mtd, &omap_sw_ooblayout_ops);
2057 		/* Reserve one byte for the OMAP marker */
2058 		oobbytes_per_step	= chip->ecc.bytes + 1;
2059 		/* Software BCH library is used for locating errors */
2060 		chip->ecc.priv		= nand_bch_init(mtd);
2061 		if (!chip->ecc.priv) {
2062 			dev_err(dev, "Unable to use BCH library\n");
2063 			return -EINVAL;
2064 		}
2065 		break;
2066 
2067 	case OMAP_ECC_BCH4_CODE_HW:
2068 		pr_info("nand: using OMAP_ECC_BCH4_CODE_HW ECC scheme\n");
2069 		chip->ecc.mode		= NAND_ECC_HW;
2070 		chip->ecc.size		= 512;
2071 		/* 14th bit is kept reserved for ROM-code compatibility */
2072 		chip->ecc.bytes		= 7 + 1;
2073 		chip->ecc.strength	= 4;
2074 		chip->ecc.hwctl		= omap_enable_hwecc_bch;
2075 		chip->ecc.correct	= omap_elm_correct_data;
2076 		chip->ecc.read_page	= omap_read_page_bch;
2077 		chip->ecc.write_page	= omap_write_page_bch;
2078 		chip->ecc.write_subpage	= omap_write_subpage_bch;
2079 		mtd_set_ooblayout(mtd, &omap_ooblayout_ops);
2080 		oobbytes_per_step	= chip->ecc.bytes;
2081 
2082 		err = elm_config(info->elm_dev, BCH4_ECC,
2083 				 mtd->writesize / chip->ecc.size,
2084 				 chip->ecc.size, chip->ecc.bytes);
2085 		if (err < 0)
2086 			return err;
2087 		break;
2088 
2089 	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
2090 		pr_info("nand: using OMAP_ECC_BCH8_CODE_HW_DETECTION_SW\n");
2091 		chip->ecc.mode		= NAND_ECC_HW;
2092 		chip->ecc.size		= 512;
2093 		chip->ecc.bytes		= 13;
2094 		chip->ecc.strength	= 8;
2095 		chip->ecc.hwctl		= omap_enable_hwecc_bch;
2096 		chip->ecc.correct	= nand_bch_correct_data;
2097 		chip->ecc.calculate	= omap_calculate_ecc_bch_sw;
2098 		mtd_set_ooblayout(mtd, &omap_sw_ooblayout_ops);
2099 		/* Reserve one byte for the OMAP marker */
2100 		oobbytes_per_step	= chip->ecc.bytes + 1;
2101 		/* Software BCH library is used for locating errors */
2102 		chip->ecc.priv		= nand_bch_init(mtd);
2103 		if (!chip->ecc.priv) {
2104 			dev_err(dev, "unable to use BCH library\n");
2105 			return -EINVAL;
2106 		}
2107 		break;
2108 
2109 	case OMAP_ECC_BCH8_CODE_HW:
2110 		pr_info("nand: using OMAP_ECC_BCH8_CODE_HW ECC scheme\n");
2111 		chip->ecc.mode		= NAND_ECC_HW;
2112 		chip->ecc.size		= 512;
2113 		/* 14th bit is kept reserved for ROM-code compatibility */
2114 		chip->ecc.bytes		= 13 + 1;
2115 		chip->ecc.strength	= 8;
2116 		chip->ecc.hwctl		= omap_enable_hwecc_bch;
2117 		chip->ecc.correct	= omap_elm_correct_data;
2118 		chip->ecc.read_page	= omap_read_page_bch;
2119 		chip->ecc.write_page	= omap_write_page_bch;
2120 		chip->ecc.write_subpage	= omap_write_subpage_bch;
2121 		mtd_set_ooblayout(mtd, &omap_ooblayout_ops);
2122 		oobbytes_per_step	= chip->ecc.bytes;
2123 
2124 		err = elm_config(info->elm_dev, BCH8_ECC,
2125 				 mtd->writesize / chip->ecc.size,
2126 				 chip->ecc.size, chip->ecc.bytes);
2127 		if (err < 0)
2128 			return err;
2129 
2130 		break;
2131 
2132 	case OMAP_ECC_BCH16_CODE_HW:
2133 		pr_info("Using OMAP_ECC_BCH16_CODE_HW ECC scheme\n");
2134 		chip->ecc.mode		= NAND_ECC_HW;
2135 		chip->ecc.size		= 512;
2136 		chip->ecc.bytes		= 26;
2137 		chip->ecc.strength	= 16;
2138 		chip->ecc.hwctl		= omap_enable_hwecc_bch;
2139 		chip->ecc.correct	= omap_elm_correct_data;
2140 		chip->ecc.read_page	= omap_read_page_bch;
2141 		chip->ecc.write_page	= omap_write_page_bch;
2142 		chip->ecc.write_subpage	= omap_write_subpage_bch;
2143 		mtd_set_ooblayout(mtd, &omap_ooblayout_ops);
2144 		oobbytes_per_step	= chip->ecc.bytes;
2145 
2146 		err = elm_config(info->elm_dev, BCH16_ECC,
2147 				 mtd->writesize / chip->ecc.size,
2148 				 chip->ecc.size, chip->ecc.bytes);
2149 		if (err < 0)
2150 			return err;
2151 
2152 		break;
2153 	default:
2154 		dev_err(dev, "Invalid or unsupported ECC scheme\n");
2155 		return -EINVAL;
2156 	}
2157 
2158 	/* Check if NAND device's OOB is enough to store ECC signatures */
2159 	min_oobbytes += (oobbytes_per_step *
2160 			 (mtd->writesize / chip->ecc.size));
2161 	if (mtd->oobsize < min_oobbytes) {
2162 		dev_err(dev,
2163 			"Not enough OOB bytes: required = %d, available=%d\n",
2164 			min_oobbytes, mtd->oobsize);
2165 		return -EINVAL;
2166 	}
2167 
2168 	return 0;
2169 }
2170 
2171 static const struct nand_controller_ops omap_nand_controller_ops = {
2172 	.attach_chip = omap_nand_attach_chip,
2173 };
2174 
2175 /* Shared among all NAND instances to synchronize access to the ECC Engine */
2176 static struct nand_controller omap_gpmc_controller = {
2177 	.lock = __SPIN_LOCK_UNLOCKED(omap_gpmc_controller.lock),
2178 	.wq = __WAIT_QUEUE_HEAD_INITIALIZER(omap_gpmc_controller.wq),
2179 	.ops = &omap_nand_controller_ops,
2180 };
2181 
2182 static int omap_nand_probe(struct platform_device *pdev)
2183 {
2184 	struct omap_nand_info		*info;
2185 	struct mtd_info			*mtd;
2186 	struct nand_chip		*nand_chip;
2187 	int				err;
2188 	struct resource			*res;
2189 	struct device			*dev = &pdev->dev;
2190 
2191 	info = devm_kzalloc(&pdev->dev, sizeof(struct omap_nand_info),
2192 				GFP_KERNEL);
2193 	if (!info)
2194 		return -ENOMEM;
2195 
2196 	info->pdev = pdev;
2197 
2198 	err = omap_get_dt_info(dev, info);
2199 	if (err)
2200 		return err;
2201 
2202 	info->ops = gpmc_omap_get_nand_ops(&info->reg, info->gpmc_cs);
2203 	if (!info->ops) {
2204 		dev_err(&pdev->dev, "Failed to get GPMC->NAND interface\n");
2205 		return -ENODEV;
2206 	}
2207 
2208 	nand_chip		= &info->nand;
2209 	mtd			= nand_to_mtd(nand_chip);
2210 	mtd->dev.parent		= &pdev->dev;
2211 	nand_chip->ecc.priv	= NULL;
2212 	nand_set_flash_node(nand_chip, dev->of_node);
2213 
2214 	if (!mtd->name) {
2215 		mtd->name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
2216 					   "omap2-nand.%d", info->gpmc_cs);
2217 		if (!mtd->name) {
2218 			dev_err(&pdev->dev, "Failed to set MTD name\n");
2219 			return -ENOMEM;
2220 		}
2221 	}
2222 
2223 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
2224 	nand_chip->legacy.IO_ADDR_R = devm_ioremap_resource(&pdev->dev, res);
2225 	if (IS_ERR(nand_chip->legacy.IO_ADDR_R))
2226 		return PTR_ERR(nand_chip->legacy.IO_ADDR_R);
2227 
2228 	info->phys_base = res->start;
2229 
2230 	nand_chip->controller = &omap_gpmc_controller;
2231 
2232 	nand_chip->legacy.IO_ADDR_W = nand_chip->legacy.IO_ADDR_R;
2233 	nand_chip->legacy.cmd_ctrl  = omap_hwcontrol;
2234 
2235 	info->ready_gpiod = devm_gpiod_get_optional(&pdev->dev, "rb",
2236 						    GPIOD_IN);
2237 	if (IS_ERR(info->ready_gpiod)) {
2238 		dev_err(dev, "failed to get ready gpio\n");
2239 		return PTR_ERR(info->ready_gpiod);
2240 	}
2241 
2242 	/*
2243 	 * If RDY/BSY line is connected to OMAP then use the omap ready
2244 	 * function and the generic nand_wait function which reads the status
2245 	 * register after monitoring the RDY/BSY line. Otherwise use a standard
2246 	 * chip delay which is slightly more than tR (AC Timing) of the NAND
2247 	 * device and read status register until you get a failure or success
2248 	 */
2249 	if (info->ready_gpiod) {
2250 		nand_chip->legacy.dev_ready = omap_dev_ready;
2251 		nand_chip->legacy.chip_delay = 0;
2252 	} else {
2253 		nand_chip->legacy.waitfunc = omap_wait;
2254 		nand_chip->legacy.chip_delay = 50;
2255 	}
2256 
2257 	if (info->flash_bbt)
2258 		nand_chip->bbt_options |= NAND_BBT_USE_FLASH;
2259 
2260 	/* scan NAND device connected to chip controller */
2261 	nand_chip->options |= info->devsize & NAND_BUSWIDTH_16;
2262 
2263 	err = nand_scan(nand_chip, 1);
2264 	if (err)
2265 		goto return_error;
2266 
2267 	err = mtd_device_register(mtd, NULL, 0);
2268 	if (err)
2269 		goto cleanup_nand;
2270 
2271 	platform_set_drvdata(pdev, mtd);
2272 
2273 	return 0;
2274 
2275 cleanup_nand:
2276 	nand_cleanup(nand_chip);
2277 
2278 return_error:
2279 	if (!IS_ERR_OR_NULL(info->dma))
2280 		dma_release_channel(info->dma);
2281 	if (nand_chip->ecc.priv) {
2282 		nand_bch_free(nand_chip->ecc.priv);
2283 		nand_chip->ecc.priv = NULL;
2284 	}
2285 	return err;
2286 }
2287 
2288 static int omap_nand_remove(struct platform_device *pdev)
2289 {
2290 	struct mtd_info *mtd = platform_get_drvdata(pdev);
2291 	struct nand_chip *nand_chip = mtd_to_nand(mtd);
2292 	struct omap_nand_info *info = mtd_to_omap(mtd);
2293 	if (nand_chip->ecc.priv) {
2294 		nand_bch_free(nand_chip->ecc.priv);
2295 		nand_chip->ecc.priv = NULL;
2296 	}
2297 	if (info->dma)
2298 		dma_release_channel(info->dma);
2299 	nand_release(nand_chip);
2300 	return 0;
2301 }
2302 
2303 static const struct of_device_id omap_nand_ids[] = {
2304 	{ .compatible = "ti,omap2-nand", },
2305 	{},
2306 };
2307 MODULE_DEVICE_TABLE(of, omap_nand_ids);
2308 
2309 static struct platform_driver omap_nand_driver = {
2310 	.probe		= omap_nand_probe,
2311 	.remove		= omap_nand_remove,
2312 	.driver		= {
2313 		.name	= DRIVER_NAME,
2314 		.of_match_table = of_match_ptr(omap_nand_ids),
2315 	},
2316 };
2317 
2318 module_platform_driver(omap_nand_driver);
2319 
2320 MODULE_ALIAS("platform:" DRIVER_NAME);
2321 MODULE_LICENSE("GPL");
2322 MODULE_DESCRIPTION("Glue layer for NAND flash on TI OMAP boards");
2323