xref: /openbmc/linux/drivers/spi/spi-mxs.c (revision b78412b8) 
1 /*
2  * Freescale MXS SPI master driver
3  *
4  * Copyright 2012 DENX Software Engineering, GmbH.
5  * Copyright 2012 Freescale Semiconductor, Inc.
6  * Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.
7  *
8  * Rework and transition to new API by:
9  * Marek Vasut <marex@denx.de>
10  *
11  * Based on previous attempt by:
12  * Fabio Estevam <fabio.estevam@freescale.com>
13  *
14  * Based on code from U-Boot bootloader by:
15  * Marek Vasut <marex@denx.de>
16  *
17  * Based on spi-stmp.c, which is:
18  * Author: Dmitry Pervushin <dimka@embeddedalley.com>
19  *
20  * This program is free software; you can redistribute it and/or modify
21  * it under the terms of the GNU General Public License as published by
22  * the Free Software Foundation; either version 2 of the License, or
23  * (at your option) any later version.
24  *
25  * This program is distributed in the hope that it will be useful,
26  * but WITHOUT ANY WARRANTY; without even the implied warranty of
27  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
28  * GNU General Public License for more details.
29  */
30 
31 #include <linux/kernel.h>
32 #include <linux/ioport.h>
33 #include <linux/of.h>
34 #include <linux/of_device.h>
35 #include <linux/of_gpio.h>
36 #include <linux/platform_device.h>
37 #include <linux/delay.h>
38 #include <linux/interrupt.h>
39 #include <linux/dma-mapping.h>
40 #include <linux/dmaengine.h>
41 #include <linux/highmem.h>
42 #include <linux/clk.h>
43 #include <linux/err.h>
44 #include <linux/completion.h>
45 #include <linux/gpio.h>
46 #include <linux/regulator/consumer.h>
47 #include <linux/module.h>
48 #include <linux/stmp_device.h>
49 #include <linux/spi/spi.h>
50 #include <linux/spi/mxs-spi.h>
51 
52 #define DRIVER_NAME		"mxs-spi"
53 
54 /* Use 10S timeout for very long transfers, it should suffice. */
55 #define SSP_TIMEOUT		10000
56 
57 #define SG_MAXLEN		0xff00
58 
59 /*
60  * Flags for txrx functions.  More efficient that using an argument register for
61  * each one.
62  */
63 #define TXRX_WRITE		(1<<0)	/* This is a write */
64 #define TXRX_DEASSERT_CS	(1<<1)	/* De-assert CS at end of txrx */
65 
66 struct mxs_spi {
67 	struct mxs_ssp		ssp;
68 	struct completion	c;
69 	unsigned int		sck;	/* Rate requested (vs actual) */
70 };
71 
72 static int mxs_spi_setup_transfer(struct spi_device *dev,
73 				  const struct spi_transfer *t)
74 {
75 	struct mxs_spi *spi = spi_master_get_devdata(dev->master);
76 	struct mxs_ssp *ssp = &spi->ssp;
77 	const unsigned int hz = min(dev->max_speed_hz, t->speed_hz);
78 
79 	if (hz == 0) {
80 		dev_err(&dev->dev, "SPI clock rate of zero not allowed\n");
81 		return -EINVAL;
82 	}
83 
84 	if (hz != spi->sck) {
85 		mxs_ssp_set_clk_rate(ssp, hz);
86 		/*
87 		 * Save requested rate, hz, rather than the actual rate,
88 		 * ssp->clk_rate.  Otherwise we would set the rate every transfer
89 		 * when the actual rate is not quite the same as requested rate.
90 		 */
91 		spi->sck = hz;
92 		/*
93 		 * Perhaps we should return an error if the actual clock is
94 		 * nowhere close to what was requested?
95 		 */
96 	}
97 
98 	writel(BM_SSP_CTRL0_LOCK_CS,
99 		ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
100 
101 	writel(BF_SSP_CTRL1_SSP_MODE(BV_SSP_CTRL1_SSP_MODE__SPI) |
102 	       BF_SSP_CTRL1_WORD_LENGTH(BV_SSP_CTRL1_WORD_LENGTH__EIGHT_BITS) |
103 	       ((dev->mode & SPI_CPOL) ? BM_SSP_CTRL1_POLARITY : 0) |
104 	       ((dev->mode & SPI_CPHA) ? BM_SSP_CTRL1_PHASE : 0),
105 	       ssp->base + HW_SSP_CTRL1(ssp));
106 
107 	writel(0x0, ssp->base + HW_SSP_CMD0);
108 	writel(0x0, ssp->base + HW_SSP_CMD1);
109 
110 	return 0;
111 }
112 
113 static u32 mxs_spi_cs_to_reg(unsigned cs)
114 {
115 	u32 select = 0;
116 
117 	/*
118 	 * i.MX28 Datasheet: 17.10.1: HW_SSP_CTRL0
119 	 *
120 	 * The bits BM_SSP_CTRL0_WAIT_FOR_CMD and BM_SSP_CTRL0_WAIT_FOR_IRQ
121 	 * in HW_SSP_CTRL0 register do have multiple usage, please refer to
122 	 * the datasheet for further details. In SPI mode, they are used to
123 	 * toggle the chip-select lines (nCS pins).
124 	 */
125 	if (cs & 1)
126 		select |= BM_SSP_CTRL0_WAIT_FOR_CMD;
127 	if (cs & 2)
128 		select |= BM_SSP_CTRL0_WAIT_FOR_IRQ;
129 
130 	return select;
131 }
132 
133 static int mxs_ssp_wait(struct mxs_spi *spi, int offset, int mask, bool set)
134 {
135 	const unsigned long timeout = jiffies + msecs_to_jiffies(SSP_TIMEOUT);
136 	struct mxs_ssp *ssp = &spi->ssp;
137 	u32 reg;
138 
139 	do {
140 		reg = readl_relaxed(ssp->base + offset);
141 
142 		if (!set)
143 			reg = ~reg;
144 
145 		reg &= mask;
146 
147 		if (reg == mask)
148 			return 0;
149 	} while (time_before(jiffies, timeout));
150 
151 	return -ETIMEDOUT;
152 }
153 
154 static void mxs_ssp_dma_irq_callback(void *param)
155 {
156 	struct mxs_spi *spi = param;
157 
158 	complete(&spi->c);
159 }
160 
161 static irqreturn_t mxs_ssp_irq_handler(int irq, void *dev_id)
162 {
163 	struct mxs_ssp *ssp = dev_id;
164 
165 	dev_err(ssp->dev, "%s[%i] CTRL1=%08x STATUS=%08x\n",
166 		__func__, __LINE__,
167 		readl(ssp->base + HW_SSP_CTRL1(ssp)),
168 		readl(ssp->base + HW_SSP_STATUS(ssp)));
169 	return IRQ_HANDLED;
170 }
171 
172 static int mxs_spi_txrx_dma(struct mxs_spi *spi,
173 			    unsigned char *buf, int len,
174 			    unsigned int flags)
175 {
176 	struct mxs_ssp *ssp = &spi->ssp;
177 	struct dma_async_tx_descriptor *desc = NULL;
178 	const bool vmalloced_buf = is_vmalloc_addr(buf);
179 	const int desc_len = vmalloced_buf ? PAGE_SIZE : SG_MAXLEN;
180 	const int sgs = DIV_ROUND_UP(len, desc_len);
181 	int sg_count;
182 	int min, ret;
183 	u32 ctrl0;
184 	struct page *vm_page;
185 	struct {
186 		u32			pio[4];
187 		struct scatterlist	sg;
188 	} *dma_xfer;
189 
190 	if (!len)
191 		return -EINVAL;
192 
193 	dma_xfer = kcalloc(sgs, sizeof(*dma_xfer), GFP_KERNEL);
194 	if (!dma_xfer)
195 		return -ENOMEM;
196 
197 	reinit_completion(&spi->c);
198 
199 	/* Chip select was already programmed into CTRL0 */
200 	ctrl0 = readl(ssp->base + HW_SSP_CTRL0);
201 	ctrl0 &= ~(BM_SSP_CTRL0_XFER_COUNT | BM_SSP_CTRL0_IGNORE_CRC |
202 		 BM_SSP_CTRL0_READ);
203 	ctrl0 |= BM_SSP_CTRL0_DATA_XFER;
204 
205 	if (!(flags & TXRX_WRITE))
206 		ctrl0 |= BM_SSP_CTRL0_READ;
207 
208 	/* Queue the DMA data transfer. */
209 	for (sg_count = 0; sg_count < sgs; sg_count++) {
210 		/* Prepare the transfer descriptor. */
211 		min = min(len, desc_len);
212 
213 		/*
214 		 * De-assert CS on last segment if flag is set (i.e., no more
215 		 * transfers will follow)
216 		 */
217 		if ((sg_count + 1 == sgs) && (flags & TXRX_DEASSERT_CS))
218 			ctrl0 |= BM_SSP_CTRL0_IGNORE_CRC;
219 
220 		if (ssp->devid == IMX23_SSP) {
221 			ctrl0 &= ~BM_SSP_CTRL0_XFER_COUNT;
222 			ctrl0 |= min;
223 		}
224 
225 		dma_xfer[sg_count].pio[0] = ctrl0;
226 		dma_xfer[sg_count].pio[3] = min;
227 
228 		if (vmalloced_buf) {
229 			vm_page = vmalloc_to_page(buf);
230 			if (!vm_page) {
231 				ret = -ENOMEM;
232 				goto err_vmalloc;
233 			}
234 
235 			sg_init_table(&dma_xfer[sg_count].sg, 1);
236 			sg_set_page(&dma_xfer[sg_count].sg, vm_page,
237 				    min, offset_in_page(buf));
238 		} else {
239 			sg_init_one(&dma_xfer[sg_count].sg, buf, min);
240 		}
241 
242 		ret = dma_map_sg(ssp->dev, &dma_xfer[sg_count].sg, 1,
243 			(flags & TXRX_WRITE) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
244 
245 		len -= min;
246 		buf += min;
247 
248 		/* Queue the PIO register write transfer. */
249 		desc = dmaengine_prep_slave_sg(ssp->dmach,
250 				(struct scatterlist *)dma_xfer[sg_count].pio,
251 				(ssp->devid == IMX23_SSP) ? 1 : 4,
252 				DMA_TRANS_NONE,
253 				sg_count ? DMA_PREP_INTERRUPT : 0);
254 		if (!desc) {
255 			dev_err(ssp->dev,
256 				"Failed to get PIO reg. write descriptor.\n");
257 			ret = -EINVAL;
258 			goto err_mapped;
259 		}
260 
261 		desc = dmaengine_prep_slave_sg(ssp->dmach,
262 				&dma_xfer[sg_count].sg, 1,
263 				(flags & TXRX_WRITE) ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
264 				DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
265 
266 		if (!desc) {
267 			dev_err(ssp->dev,
268 				"Failed to get DMA data write descriptor.\n");
269 			ret = -EINVAL;
270 			goto err_mapped;
271 		}
272 	}
273 
274 	/*
275 	 * The last descriptor must have this callback,
276 	 * to finish the DMA transaction.
277 	 */
278 	desc->callback = mxs_ssp_dma_irq_callback;
279 	desc->callback_param = spi;
280 
281 	/* Start the transfer. */
282 	dmaengine_submit(desc);
283 	dma_async_issue_pending(ssp->dmach);
284 
285 	if (!wait_for_completion_timeout(&spi->c,
286 					 msecs_to_jiffies(SSP_TIMEOUT))) {
287 		dev_err(ssp->dev, "DMA transfer timeout\n");
288 		ret = -ETIMEDOUT;
289 		dmaengine_terminate_all(ssp->dmach);
290 		goto err_vmalloc;
291 	}
292 
293 	ret = 0;
294 
295 err_vmalloc:
296 	while (--sg_count >= 0) {
297 err_mapped:
298 		dma_unmap_sg(ssp->dev, &dma_xfer[sg_count].sg, 1,
299 			(flags & TXRX_WRITE) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
300 	}
301 
302 	kfree(dma_xfer);
303 
304 	return ret;
305 }
306 
307 static int mxs_spi_txrx_pio(struct mxs_spi *spi,
308 			    unsigned char *buf, int len,
309 			    unsigned int flags)
310 {
311 	struct mxs_ssp *ssp = &spi->ssp;
312 
313 	writel(BM_SSP_CTRL0_IGNORE_CRC,
314 	       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
315 
316 	while (len--) {
317 		if (len == 0 && (flags & TXRX_DEASSERT_CS))
318 			writel(BM_SSP_CTRL0_IGNORE_CRC,
319 			       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
320 
321 		if (ssp->devid == IMX23_SSP) {
322 			writel(BM_SSP_CTRL0_XFER_COUNT,
323 				ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
324 			writel(1,
325 				ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
326 		} else {
327 			writel(1, ssp->base + HW_SSP_XFER_SIZE);
328 		}
329 
330 		if (flags & TXRX_WRITE)
331 			writel(BM_SSP_CTRL0_READ,
332 				ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
333 		else
334 			writel(BM_SSP_CTRL0_READ,
335 				ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
336 
337 		writel(BM_SSP_CTRL0_RUN,
338 				ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
339 
340 		if (mxs_ssp_wait(spi, HW_SSP_CTRL0, BM_SSP_CTRL0_RUN, 1))
341 			return -ETIMEDOUT;
342 
343 		if (flags & TXRX_WRITE)
344 			writel(*buf, ssp->base + HW_SSP_DATA(ssp));
345 
346 		writel(BM_SSP_CTRL0_DATA_XFER,
347 			     ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
348 
349 		if (!(flags & TXRX_WRITE)) {
350 			if (mxs_ssp_wait(spi, HW_SSP_STATUS(ssp),
351 						BM_SSP_STATUS_FIFO_EMPTY, 0))
352 				return -ETIMEDOUT;
353 
354 			*buf = (readl(ssp->base + HW_SSP_DATA(ssp)) & 0xff);
355 		}
356 
357 		if (mxs_ssp_wait(spi, HW_SSP_CTRL0, BM_SSP_CTRL0_RUN, 0))
358 			return -ETIMEDOUT;
359 
360 		buf++;
361 	}
362 
363 	if (len <= 0)
364 		return 0;
365 
366 	return -ETIMEDOUT;
367 }
368 
369 static int mxs_spi_transfer_one(struct spi_master *master,
370 				struct spi_message *m)
371 {
372 	struct mxs_spi *spi = spi_master_get_devdata(master);
373 	struct mxs_ssp *ssp = &spi->ssp;
374 	struct spi_transfer *t;
375 	unsigned int flag;
376 	int status = 0;
377 
378 	/* Program CS register bits here, it will be used for all transfers. */
379 	writel(BM_SSP_CTRL0_WAIT_FOR_CMD | BM_SSP_CTRL0_WAIT_FOR_IRQ,
380 	       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
381 	writel(mxs_spi_cs_to_reg(m->spi->chip_select),
382 	       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
383 
384 	list_for_each_entry(t, &m->transfers, transfer_list) {
385 
386 		status = mxs_spi_setup_transfer(m->spi, t);
387 		if (status)
388 			break;
389 
390 		/* De-assert on last transfer, inverted by cs_change flag */
391 		flag = (&t->transfer_list == m->transfers.prev) ^ t->cs_change ?
392 		       TXRX_DEASSERT_CS : 0;
393 
394 		/*
395 		 * Small blocks can be transfered via PIO.
396 		 * Measured by empiric means:
397 		 *
398 		 * dd if=/dev/mtdblock0 of=/dev/null bs=1024k count=1
399 		 *
400 		 * DMA only: 2.164808 seconds, 473.0KB/s
401 		 * Combined: 1.676276 seconds, 610.9KB/s
402 		 */
403 		if (t->len < 32) {
404 			writel(BM_SSP_CTRL1_DMA_ENABLE,
405 				ssp->base + HW_SSP_CTRL1(ssp) +
406 				STMP_OFFSET_REG_CLR);
407 
408 			if (t->tx_buf)
409 				status = mxs_spi_txrx_pio(spi,
410 						(void *)t->tx_buf,
411 						t->len, flag | TXRX_WRITE);
412 			if (t->rx_buf)
413 				status = mxs_spi_txrx_pio(spi,
414 						t->rx_buf, t->len,
415 						flag);
416 		} else {
417 			writel(BM_SSP_CTRL1_DMA_ENABLE,
418 				ssp->base + HW_SSP_CTRL1(ssp) +
419 				STMP_OFFSET_REG_SET);
420 
421 			if (t->tx_buf)
422 				status = mxs_spi_txrx_dma(spi,
423 						(void *)t->tx_buf, t->len,
424 						flag | TXRX_WRITE);
425 			if (t->rx_buf)
426 				status = mxs_spi_txrx_dma(spi,
427 						t->rx_buf, t->len,
428 						flag);
429 		}
430 
431 		if (status) {
432 			stmp_reset_block(ssp->base);
433 			break;
434 		}
435 
436 		m->actual_length += t->len;
437 	}
438 
439 	m->status = status;
440 	spi_finalize_current_message(master);
441 
442 	return status;
443 }
444 
445 static const struct of_device_id mxs_spi_dt_ids[] = {
446 	{ .compatible = "fsl,imx23-spi", .data = (void *) IMX23_SSP, },
447 	{ .compatible = "fsl,imx28-spi", .data = (void *) IMX28_SSP, },
448 	{ /* sentinel */ }
449 };
450 MODULE_DEVICE_TABLE(of, mxs_spi_dt_ids);
451 
452 static int mxs_spi_probe(struct platform_device *pdev)
453 {
454 	const struct of_device_id *of_id =
455 			of_match_device(mxs_spi_dt_ids, &pdev->dev);
456 	struct device_node *np = pdev->dev.of_node;
457 	struct spi_master *master;
458 	struct mxs_spi *spi;
459 	struct mxs_ssp *ssp;
460 	struct resource *iores;
461 	struct clk *clk;
462 	void __iomem *base;
463 	int devid, clk_freq;
464 	int ret = 0, irq_err;
465 
466 	/*
467 	 * Default clock speed for the SPI core. 160MHz seems to
468 	 * work reasonably well with most SPI flashes, so use this
469 	 * as a default. Override with "clock-frequency" DT prop.
470 	 */
471 	const int clk_freq_default = 160000000;
472 
473 	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
474 	irq_err = platform_get_irq(pdev, 0);
475 	if (irq_err < 0)
476 		return irq_err;
477 
478 	base = devm_ioremap_resource(&pdev->dev, iores);
479 	if (IS_ERR(base))
480 		return PTR_ERR(base);
481 
482 	clk = devm_clk_get(&pdev->dev, NULL);
483 	if (IS_ERR(clk))
484 		return PTR_ERR(clk);
485 
486 	devid = (enum mxs_ssp_id) of_id->data;
487 	ret = of_property_read_u32(np, "clock-frequency",
488 				   &clk_freq);
489 	if (ret)
490 		clk_freq = clk_freq_default;
491 
492 	master = spi_alloc_master(&pdev->dev, sizeof(*spi));
493 	if (!master)
494 		return -ENOMEM;
495 
496 	master->transfer_one_message = mxs_spi_transfer_one;
497 	master->bits_per_word_mask = SPI_BPW_MASK(8);
498 	master->mode_bits = SPI_CPOL | SPI_CPHA;
499 	master->num_chipselect = 3;
500 	master->dev.of_node = np;
501 	master->flags = SPI_MASTER_HALF_DUPLEX;
502 
503 	spi = spi_master_get_devdata(master);
504 	ssp = &spi->ssp;
505 	ssp->dev = &pdev->dev;
506 	ssp->clk = clk;
507 	ssp->base = base;
508 	ssp->devid = devid;
509 
510 	init_completion(&spi->c);
511 
512 	ret = devm_request_irq(&pdev->dev, irq_err, mxs_ssp_irq_handler, 0,
513 			       dev_name(&pdev->dev), ssp);
514 	if (ret)
515 		goto out_master_free;
516 
517 	ssp->dmach = dma_request_slave_channel(&pdev->dev, "rx-tx");
518 	if (!ssp->dmach) {
519 		dev_err(ssp->dev, "Failed to request DMA\n");
520 		ret = -ENODEV;
521 		goto out_master_free;
522 	}
523 
524 	ret = clk_prepare_enable(ssp->clk);
525 	if (ret)
526 		goto out_dma_release;
527 
528 	clk_set_rate(ssp->clk, clk_freq);
529 
530 	ret = stmp_reset_block(ssp->base);
531 	if (ret)
532 		goto out_disable_clk;
533 
534 	platform_set_drvdata(pdev, master);
535 
536 	ret = devm_spi_register_master(&pdev->dev, master);
537 	if (ret) {
538 		dev_err(&pdev->dev, "Cannot register SPI master, %d\n", ret);
539 		goto out_disable_clk;
540 	}
541 
542 	return 0;
543 
544 out_disable_clk:
545 	clk_disable_unprepare(ssp->clk);
546 out_dma_release:
547 	dma_release_channel(ssp->dmach);
548 out_master_free:
549 	spi_master_put(master);
550 	return ret;
551 }
552 
553 static int mxs_spi_remove(struct platform_device *pdev)
554 {
555 	struct spi_master *master;
556 	struct mxs_spi *spi;
557 	struct mxs_ssp *ssp;
558 
559 	master = platform_get_drvdata(pdev);
560 	spi = spi_master_get_devdata(master);
561 	ssp = &spi->ssp;
562 
563 	clk_disable_unprepare(ssp->clk);
564 	dma_release_channel(ssp->dmach);
565 
566 	return 0;
567 }
568 
569 static struct platform_driver mxs_spi_driver = {
570 	.probe	= mxs_spi_probe,
571 	.remove	= mxs_spi_remove,
572 	.driver	= {
573 		.name	= DRIVER_NAME,
574 		.of_match_table = mxs_spi_dt_ids,
575 	},
576 };
577 
578 module_platform_driver(mxs_spi_driver);
579 
580 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
581 MODULE_DESCRIPTION("MXS SPI master driver");
582 MODULE_LICENSE("GPL");
583 MODULE_ALIAS("platform:mxs-spi");
584