1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * SuperH Mobile I2C Controller
4  *
5  * Copyright (C) 2014-19 Wolfram Sang <wsa@sang-engineering.com>
6  * Copyright (C) 2008 Magnus Damm
7  *
8  * Portions of the code based on out-of-tree driver i2c-sh7343.c
9  * Copyright (c) 2006 Carlos Munoz <carlos@kenati.com>
10  */
11 
12 #include <linux/clk.h>
13 #include <linux/delay.h>
14 #include <linux/dmaengine.h>
15 #include <linux/dma-mapping.h>
16 #include <linux/err.h>
17 #include <linux/i2c.h>
18 #include <linux/init.h>
19 #include <linux/interrupt.h>
20 #include <linux/io.h>
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/of.h>
24 #include <linux/platform_device.h>
25 #include <linux/pm_runtime.h>
26 #include <linux/slab.h>
27 
28 /* Transmit operation:                                                      */
29 /*                                                                          */
30 /* 0 byte transmit                                                          */
31 /* BUS:     S     A8     ACK   P(*)                                         */
32 /* IRQ:       DTE   WAIT                                                    */
33 /* ICIC:                                                                    */
34 /* ICCR: 0x94       0x90                                                    */
35 /* ICDR:      A8                                                            */
36 /*                                                                          */
37 /* 1 byte transmit                                                          */
38 /* BUS:     S     A8     ACK   D8(1)   ACK   P(*)                           */
39 /* IRQ:       DTE   WAIT         WAIT                                       */
40 /* ICIC:      -DTE                                                          */
41 /* ICCR: 0x94                    0x90                                       */
42 /* ICDR:      A8    D8(1)                                                   */
43 /*                                                                          */
44 /* 2 byte transmit                                                          */
45 /* BUS:     S     A8     ACK   D8(1)   ACK   D8(2)   ACK   P(*)             */
46 /* IRQ:       DTE   WAIT         WAIT          WAIT                         */
47 /* ICIC:      -DTE                                                          */
48 /* ICCR: 0x94                                  0x90                         */
49 /* ICDR:      A8    D8(1)        D8(2)                                      */
50 /*                                                                          */
51 /* 3 bytes or more, +---------+ gets repeated                               */
52 /*                                                                          */
53 /*                                                                          */
54 /* Receive operation:                                                       */
55 /*                                                                          */
56 /* 0 byte receive - not supported since slave may hold SDA low              */
57 /*                                                                          */
58 /* 1 byte receive       [TX] | [RX]                                         */
59 /* BUS:     S     A8     ACK | D8(1)   ACK   P(*)                           */
60 /* IRQ:       DTE   WAIT     |   WAIT     DTE                               */
61 /* ICIC:      -DTE           |   +DTE                                       */
62 /* ICCR: 0x94       0x81     |   0xc0                                       */
63 /* ICDR:      A8             |            D8(1)                             */
64 /*                                                                          */
65 /* 2 byte receive        [TX]| [RX]                                         */
66 /* BUS:     S     A8     ACK | D8(1)   ACK   D8(2)   ACK   P(*)             */
67 /* IRQ:       DTE   WAIT     |   WAIT          WAIT     DTE                 */
68 /* ICIC:      -DTE           |                 +DTE                         */
69 /* ICCR: 0x94       0x81     |                 0xc0                         */
70 /* ICDR:      A8             |                 D8(1)    D8(2)               */
71 /*                                                                          */
72 /* 3 byte receive       [TX] | [RX]                                     (*) */
73 /* BUS:     S     A8     ACK | D8(1)   ACK   D8(2)   ACK   D8(3)   ACK    P */
74 /* IRQ:       DTE   WAIT     |   WAIT          WAIT         WAIT      DTE   */
75 /* ICIC:      -DTE           |                              +DTE            */
76 /* ICCR: 0x94       0x81     |                              0xc0            */
77 /* ICDR:      A8             |                 D8(1)        D8(2)     D8(3) */
78 /*                                                                          */
79 /* 4 bytes or more, this part is repeated    +---------+                    */
80 /*                                                                          */
81 /*                                                                          */
82 /* Interrupt order and BUSY flag                                            */
83 /*     ___                                                 _                */
84 /* SDA ___\___XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXAAAAAAAAA___/                 */
85 /* SCL      \_/1\_/2\_/3\_/4\_/5\_/6\_/7\_/8\___/9\_____/                   */
86 /*                                                                          */
87 /*        S   D7  D6  D5  D4  D3  D2  D1  D0              P(*)              */
88 /*                                           ___                            */
89 /* WAIT IRQ ________________________________/   \___________                */
90 /* TACK IRQ ____________________________________/   \_______                */
91 /* DTE  IRQ __________________________________________/   \_                */
92 /* AL   IRQ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                */
93 /*         _______________________________________________                  */
94 /* BUSY __/                                               \_                */
95 /*                                                                          */
96 /* (*) The STOP condition is only sent by the master at the end of the last */
97 /* I2C message or if the I2C_M_STOP flag is set. Similarly, the BUSY bit is */
98 /* only cleared after the STOP condition, so, between messages we have to   */
99 /* poll for the DTE bit.                                                    */
100 /*                                                                          */
101 
102 enum sh_mobile_i2c_op {
103 	OP_START = 0,
104 	OP_TX_FIRST,
105 	OP_TX,
106 	OP_TX_STOP,
107 	OP_TX_TO_RX,
108 	OP_RX,
109 	OP_RX_STOP,
110 	OP_RX_STOP_DATA,
111 };
112 
113 struct sh_mobile_i2c_data {
114 	struct device *dev;
115 	void __iomem *reg;
116 	struct i2c_adapter adap;
117 	unsigned long bus_speed;
118 	unsigned int clks_per_count;
119 	struct clk *clk;
120 	u_int8_t icic;
121 	u_int8_t flags;
122 	u_int16_t iccl;
123 	u_int16_t icch;
124 
125 	spinlock_t lock;
126 	wait_queue_head_t wait;
127 	struct i2c_msg *msg;
128 	int pos;
129 	int sr;
130 	bool send_stop;
131 	bool stop_after_dma;
132 	bool atomic_xfer;
133 
134 	struct resource *res;
135 	struct dma_chan *dma_tx;
136 	struct dma_chan *dma_rx;
137 	struct scatterlist sg;
138 	enum dma_data_direction dma_direction;
139 	u8 *dma_buf;
140 };
141 
142 struct sh_mobile_dt_config {
143 	int clks_per_count;
144 	int (*setup)(struct sh_mobile_i2c_data *pd);
145 };
146 
147 #define IIC_FLAG_HAS_ICIC67	(1 << 0)
148 
149 /* Register offsets */
150 #define ICDR			0x00
151 #define ICCR			0x04
152 #define ICSR			0x08
153 #define ICIC			0x0c
154 #define ICCL			0x10
155 #define ICCH			0x14
156 #define ICSTART			0x70
157 
158 /* Register bits */
159 #define ICCR_ICE		0x80
160 #define ICCR_RACK		0x40
161 #define ICCR_TRS		0x10
162 #define ICCR_BBSY		0x04
163 #define ICCR_SCP		0x01
164 
165 #define ICSR_SCLM		0x80
166 #define ICSR_SDAM		0x40
167 #define SW_DONE			0x20
168 #define ICSR_BUSY		0x10
169 #define ICSR_AL			0x08
170 #define ICSR_TACK		0x04
171 #define ICSR_WAIT		0x02
172 #define ICSR_DTE		0x01
173 
174 #define ICIC_ICCLB8		0x80
175 #define ICIC_ICCHB8		0x40
176 #define ICIC_TDMAE		0x20
177 #define ICIC_RDMAE		0x10
178 #define ICIC_ALE		0x08
179 #define ICIC_TACKE		0x04
180 #define ICIC_WAITE		0x02
181 #define ICIC_DTEE		0x01
182 
183 #define ICSTART_ICSTART		0x10
184 
iic_wr(struct sh_mobile_i2c_data * pd,int offs,unsigned char data)185 static void iic_wr(struct sh_mobile_i2c_data *pd, int offs, unsigned char data)
186 {
187 	if (offs == ICIC)
188 		data |= pd->icic;
189 
190 	iowrite8(data, pd->reg + offs);
191 }
192 
iic_rd(struct sh_mobile_i2c_data * pd,int offs)193 static unsigned char iic_rd(struct sh_mobile_i2c_data *pd, int offs)
194 {
195 	return ioread8(pd->reg + offs);
196 }
197 
iic_set_clr(struct sh_mobile_i2c_data * pd,int offs,unsigned char set,unsigned char clr)198 static void iic_set_clr(struct sh_mobile_i2c_data *pd, int offs,
199 			unsigned char set, unsigned char clr)
200 {
201 	iic_wr(pd, offs, (iic_rd(pd, offs) | set) & ~clr);
202 }
203 
sh_mobile_i2c_iccl(unsigned long count_khz,u32 tLOW,u32 tf)204 static u32 sh_mobile_i2c_iccl(unsigned long count_khz, u32 tLOW, u32 tf)
205 {
206 	/*
207 	 * Conditional expression:
208 	 *   ICCL >= COUNT_CLK * (tLOW + tf)
209 	 *
210 	 * SH-Mobile IIC hardware starts counting the LOW period of
211 	 * the SCL signal (tLOW) as soon as it pulls the SCL line.
212 	 * In order to meet the tLOW timing spec, we need to take into
213 	 * account the fall time of SCL signal (tf).  Default tf value
214 	 * should be 0.3 us, for safety.
215 	 */
216 	return (((count_khz * (tLOW + tf)) + 5000) / 10000);
217 }
218 
sh_mobile_i2c_icch(unsigned long count_khz,u32 tHIGH,u32 tf)219 static u32 sh_mobile_i2c_icch(unsigned long count_khz, u32 tHIGH, u32 tf)
220 {
221 	/*
222 	 * Conditional expression:
223 	 *   ICCH >= COUNT_CLK * (tHIGH + tf)
224 	 *
225 	 * SH-Mobile IIC hardware is aware of SCL transition period 'tr',
226 	 * and can ignore it.  SH-Mobile IIC controller starts counting
227 	 * the HIGH period of the SCL signal (tHIGH) after the SCL input
228 	 * voltage increases at VIH.
229 	 *
230 	 * Afterward it turned out calculating ICCH using only tHIGH spec
231 	 * will result in violation of the tHD;STA timing spec.  We need
232 	 * to take into account the fall time of SDA signal (tf) at START
233 	 * condition, in order to meet both tHIGH and tHD;STA specs.
234 	 */
235 	return (((count_khz * (tHIGH + tf)) + 5000) / 10000);
236 }
237 
sh_mobile_i2c_check_timing(struct sh_mobile_i2c_data * pd)238 static int sh_mobile_i2c_check_timing(struct sh_mobile_i2c_data *pd)
239 {
240 	u16 max_val = pd->flags & IIC_FLAG_HAS_ICIC67 ? 0x1ff : 0xff;
241 
242 	if (pd->iccl > max_val || pd->icch > max_val) {
243 		dev_err(pd->dev, "timing values out of range: L/H=0x%x/0x%x\n",
244 			pd->iccl, pd->icch);
245 		return -EINVAL;
246 	}
247 
248 	/* one more bit of ICCL in ICIC */
249 	if (pd->iccl & 0x100)
250 		pd->icic |= ICIC_ICCLB8;
251 	else
252 		pd->icic &= ~ICIC_ICCLB8;
253 
254 	/* one more bit of ICCH in ICIC */
255 	if (pd->icch & 0x100)
256 		pd->icic |= ICIC_ICCHB8;
257 	else
258 		pd->icic &= ~ICIC_ICCHB8;
259 
260 	dev_dbg(pd->dev, "timing values: L/H=0x%x/0x%x\n", pd->iccl, pd->icch);
261 	return 0;
262 }
263 
sh_mobile_i2c_init(struct sh_mobile_i2c_data * pd)264 static int sh_mobile_i2c_init(struct sh_mobile_i2c_data *pd)
265 {
266 	unsigned long i2c_clk_khz;
267 	u32 tHIGH, tLOW, tf;
268 
269 	i2c_clk_khz = clk_get_rate(pd->clk) / 1000 / pd->clks_per_count;
270 
271 	if (pd->bus_speed == I2C_MAX_STANDARD_MODE_FREQ) {
272 		tLOW	= 47;	/* tLOW = 4.7 us */
273 		tHIGH	= 40;	/* tHD;STA = tHIGH = 4.0 us */
274 		tf	= 3;	/* tf = 0.3 us */
275 	} else if (pd->bus_speed == I2C_MAX_FAST_MODE_FREQ) {
276 		tLOW	= 13;	/* tLOW = 1.3 us */
277 		tHIGH	= 6;	/* tHD;STA = tHIGH = 0.6 us */
278 		tf	= 3;	/* tf = 0.3 us */
279 	} else {
280 		dev_err(pd->dev, "unrecognized bus speed %lu Hz\n",
281 			pd->bus_speed);
282 		return -EINVAL;
283 	}
284 
285 	pd->iccl = sh_mobile_i2c_iccl(i2c_clk_khz, tLOW, tf);
286 	pd->icch = sh_mobile_i2c_icch(i2c_clk_khz, tHIGH, tf);
287 
288 	return sh_mobile_i2c_check_timing(pd);
289 }
290 
sh_mobile_i2c_v2_init(struct sh_mobile_i2c_data * pd)291 static int sh_mobile_i2c_v2_init(struct sh_mobile_i2c_data *pd)
292 {
293 	unsigned long clks_per_cycle;
294 
295 	/* L = 5, H = 4, L + H = 9 */
296 	clks_per_cycle = clk_get_rate(pd->clk) / pd->bus_speed;
297 	pd->iccl = DIV_ROUND_UP(clks_per_cycle * 5 / 9 - 1, pd->clks_per_count);
298 	pd->icch = DIV_ROUND_UP(clks_per_cycle * 4 / 9 - 5, pd->clks_per_count);
299 
300 	return sh_mobile_i2c_check_timing(pd);
301 }
302 
i2c_op(struct sh_mobile_i2c_data * pd,enum sh_mobile_i2c_op op)303 static unsigned char i2c_op(struct sh_mobile_i2c_data *pd, enum sh_mobile_i2c_op op)
304 {
305 	unsigned char ret = 0;
306 	unsigned long flags;
307 
308 	dev_dbg(pd->dev, "op %d\n", op);
309 
310 	spin_lock_irqsave(&pd->lock, flags);
311 
312 	switch (op) {
313 	case OP_START: /* issue start and trigger DTE interrupt */
314 		iic_wr(pd, ICCR, ICCR_ICE | ICCR_TRS | ICCR_BBSY);
315 		break;
316 	case OP_TX_FIRST: /* disable DTE interrupt and write client address */
317 		iic_wr(pd, ICIC, ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
318 		iic_wr(pd, ICDR, i2c_8bit_addr_from_msg(pd->msg));
319 		break;
320 	case OP_TX: /* write data */
321 		iic_wr(pd, ICDR, pd->msg->buf[pd->pos]);
322 		break;
323 	case OP_TX_STOP: /* issue a stop (or rep_start) */
324 		iic_wr(pd, ICCR, pd->send_stop ? ICCR_ICE | ICCR_TRS
325 					       : ICCR_ICE | ICCR_TRS | ICCR_BBSY);
326 		break;
327 	case OP_TX_TO_RX: /* select read mode */
328 		iic_wr(pd, ICCR, ICCR_ICE | ICCR_SCP);
329 		break;
330 	case OP_RX: /* just read data */
331 		ret = iic_rd(pd, ICDR);
332 		break;
333 	case OP_RX_STOP: /* enable DTE interrupt, issue stop */
334 		if (!pd->atomic_xfer)
335 			iic_wr(pd, ICIC,
336 			       ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
337 		iic_wr(pd, ICCR, ICCR_ICE | ICCR_RACK);
338 		break;
339 	case OP_RX_STOP_DATA: /* enable DTE interrupt, read data, issue stop */
340 		if (!pd->atomic_xfer)
341 			iic_wr(pd, ICIC,
342 			       ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
343 		ret = iic_rd(pd, ICDR);
344 		iic_wr(pd, ICCR, ICCR_ICE | ICCR_RACK);
345 		break;
346 	}
347 
348 	spin_unlock_irqrestore(&pd->lock, flags);
349 
350 	dev_dbg(pd->dev, "op %d, data out 0x%02x\n", op, ret);
351 	return ret;
352 }
353 
sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data * pd)354 static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
355 {
356 	if (pd->pos == pd->msg->len) {
357 		i2c_op(pd, OP_TX_STOP);
358 		return 1;
359 	}
360 
361 	if (pd->pos == -1)
362 		i2c_op(pd, OP_TX_FIRST);
363 	else
364 		i2c_op(pd, OP_TX);
365 
366 	pd->pos++;
367 	return 0;
368 }
369 
sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data * pd)370 static int sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data *pd)
371 {
372 	int real_pos;
373 
374 	/* switch from TX (address) to RX (data) adds two interrupts */
375 	real_pos = pd->pos - 2;
376 
377 	if (pd->pos == -1) {
378 		i2c_op(pd, OP_TX_FIRST);
379 	} else if (pd->pos == 0) {
380 		i2c_op(pd, OP_TX_TO_RX);
381 	} else if (pd->pos == pd->msg->len) {
382 		if (pd->stop_after_dma) {
383 			/* Simulate PIO end condition after DMA transfer */
384 			i2c_op(pd, OP_RX_STOP);
385 			pd->pos++;
386 			goto done;
387 		}
388 
389 		if (real_pos < 0)
390 			i2c_op(pd, OP_RX_STOP);
391 		else
392 			pd->msg->buf[real_pos] = i2c_op(pd, OP_RX_STOP_DATA);
393 	} else if (real_pos >= 0) {
394 		pd->msg->buf[real_pos] = i2c_op(pd, OP_RX);
395 	}
396 
397  done:
398 	pd->pos++;
399 	return pd->pos == (pd->msg->len + 2);
400 }
401 
sh_mobile_i2c_isr(int irq,void * dev_id)402 static irqreturn_t sh_mobile_i2c_isr(int irq, void *dev_id)
403 {
404 	struct sh_mobile_i2c_data *pd = dev_id;
405 	unsigned char sr;
406 	int wakeup = 0;
407 
408 	sr = iic_rd(pd, ICSR);
409 	pd->sr |= sr; /* remember state */
410 
411 	dev_dbg(pd->dev, "i2c_isr 0x%02x 0x%02x %s %d %d!\n", sr, pd->sr,
412 	       (pd->msg->flags & I2C_M_RD) ? "read" : "write",
413 	       pd->pos, pd->msg->len);
414 
415 	/* Kick off TxDMA after preface was done */
416 	if (pd->dma_direction == DMA_TO_DEVICE && pd->pos == 0)
417 		iic_set_clr(pd, ICIC, ICIC_TDMAE, 0);
418 	else if (sr & (ICSR_AL | ICSR_TACK))
419 		/* don't interrupt transaction - continue to issue stop */
420 		iic_wr(pd, ICSR, sr & ~(ICSR_AL | ICSR_TACK));
421 	else if (pd->msg->flags & I2C_M_RD)
422 		wakeup = sh_mobile_i2c_isr_rx(pd);
423 	else
424 		wakeup = sh_mobile_i2c_isr_tx(pd);
425 
426 	/* Kick off RxDMA after preface was done */
427 	if (pd->dma_direction == DMA_FROM_DEVICE && pd->pos == 1)
428 		iic_set_clr(pd, ICIC, ICIC_RDMAE, 0);
429 
430 	if (sr & ICSR_WAIT) /* TODO: add delay here to support slow acks */
431 		iic_wr(pd, ICSR, sr & ~ICSR_WAIT);
432 
433 	if (wakeup) {
434 		pd->sr |= SW_DONE;
435 		if (!pd->atomic_xfer)
436 			wake_up(&pd->wait);
437 	}
438 
439 	/* defeat write posting to avoid spurious WAIT interrupts */
440 	iic_rd(pd, ICSR);
441 
442 	return IRQ_HANDLED;
443 }
444 
sh_mobile_i2c_cleanup_dma(struct sh_mobile_i2c_data * pd,bool terminate)445 static void sh_mobile_i2c_cleanup_dma(struct sh_mobile_i2c_data *pd, bool terminate)
446 {
447 	struct dma_chan *chan = pd->dma_direction == DMA_FROM_DEVICE
448 				? pd->dma_rx : pd->dma_tx;
449 
450 	/* only allowed from thread context! */
451 	if (terminate)
452 		dmaengine_terminate_sync(chan);
453 
454 	dma_unmap_single(chan->device->dev, sg_dma_address(&pd->sg),
455 			 pd->msg->len, pd->dma_direction);
456 
457 	pd->dma_direction = DMA_NONE;
458 }
459 
sh_mobile_i2c_dma_callback(void * data)460 static void sh_mobile_i2c_dma_callback(void *data)
461 {
462 	struct sh_mobile_i2c_data *pd = data;
463 
464 	sh_mobile_i2c_cleanup_dma(pd, false);
465 	pd->pos = pd->msg->len;
466 	pd->stop_after_dma = true;
467 
468 	iic_set_clr(pd, ICIC, 0, ICIC_TDMAE | ICIC_RDMAE);
469 }
470 
sh_mobile_i2c_request_dma_chan(struct device * dev,enum dma_transfer_direction dir,dma_addr_t port_addr)471 static struct dma_chan *sh_mobile_i2c_request_dma_chan(struct device *dev,
472 				enum dma_transfer_direction dir, dma_addr_t port_addr)
473 {
474 	struct dma_chan *chan;
475 	struct dma_slave_config cfg;
476 	char *chan_name = dir == DMA_MEM_TO_DEV ? "tx" : "rx";
477 	int ret;
478 
479 	chan = dma_request_chan(dev, chan_name);
480 	if (IS_ERR(chan)) {
481 		dev_dbg(dev, "request_channel failed for %s (%ld)\n", chan_name,
482 			PTR_ERR(chan));
483 		return chan;
484 	}
485 
486 	memset(&cfg, 0, sizeof(cfg));
487 	cfg.direction = dir;
488 	if (dir == DMA_MEM_TO_DEV) {
489 		cfg.dst_addr = port_addr;
490 		cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
491 	} else {
492 		cfg.src_addr = port_addr;
493 		cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
494 	}
495 
496 	ret = dmaengine_slave_config(chan, &cfg);
497 	if (ret) {
498 		dev_dbg(dev, "slave_config failed for %s (%d)\n", chan_name, ret);
499 		dma_release_channel(chan);
500 		return ERR_PTR(ret);
501 	}
502 
503 	dev_dbg(dev, "got DMA channel for %s\n", chan_name);
504 	return chan;
505 }
506 
sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data * pd)507 static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd)
508 {
509 	bool read = pd->msg->flags & I2C_M_RD;
510 	enum dma_data_direction dir = read ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
511 	struct dma_chan *chan = read ? pd->dma_rx : pd->dma_tx;
512 	struct dma_async_tx_descriptor *txdesc;
513 	dma_addr_t dma_addr;
514 	dma_cookie_t cookie;
515 
516 	if (PTR_ERR(chan) == -EPROBE_DEFER) {
517 		if (read)
518 			chan = pd->dma_rx = sh_mobile_i2c_request_dma_chan(pd->dev, DMA_DEV_TO_MEM,
519 									   pd->res->start + ICDR);
520 		else
521 			chan = pd->dma_tx = sh_mobile_i2c_request_dma_chan(pd->dev, DMA_MEM_TO_DEV,
522 									   pd->res->start + ICDR);
523 	}
524 
525 	if (IS_ERR(chan))
526 		return;
527 
528 	dma_addr = dma_map_single(chan->device->dev, pd->dma_buf, pd->msg->len, dir);
529 	if (dma_mapping_error(chan->device->dev, dma_addr)) {
530 		dev_dbg(pd->dev, "dma map failed, using PIO\n");
531 		return;
532 	}
533 
534 	sg_dma_len(&pd->sg) = pd->msg->len;
535 	sg_dma_address(&pd->sg) = dma_addr;
536 
537 	pd->dma_direction = dir;
538 
539 	txdesc = dmaengine_prep_slave_sg(chan, &pd->sg, 1,
540 					 read ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV,
541 					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
542 	if (!txdesc) {
543 		dev_dbg(pd->dev, "dma prep slave sg failed, using PIO\n");
544 		sh_mobile_i2c_cleanup_dma(pd, false);
545 		return;
546 	}
547 
548 	txdesc->callback = sh_mobile_i2c_dma_callback;
549 	txdesc->callback_param = pd;
550 
551 	cookie = dmaengine_submit(txdesc);
552 	if (dma_submit_error(cookie)) {
553 		dev_dbg(pd->dev, "submitting dma failed, using PIO\n");
554 		sh_mobile_i2c_cleanup_dma(pd, false);
555 		return;
556 	}
557 
558 	dma_async_issue_pending(chan);
559 }
560 
start_ch(struct sh_mobile_i2c_data * pd,struct i2c_msg * usr_msg,bool do_init)561 static void start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg,
562 		     bool do_init)
563 {
564 	if (do_init) {
565 		/* Initialize channel registers */
566 		iic_wr(pd, ICCR, ICCR_SCP);
567 
568 		/* Enable channel and configure rx ack */
569 		iic_wr(pd, ICCR, ICCR_ICE | ICCR_SCP);
570 
571 		/* Set the clock */
572 		iic_wr(pd, ICCL, pd->iccl & 0xff);
573 		iic_wr(pd, ICCH, pd->icch & 0xff);
574 	}
575 
576 	pd->msg = usr_msg;
577 	pd->pos = -1;
578 	pd->sr = 0;
579 
580 	if (pd->atomic_xfer)
581 		return;
582 
583 	pd->dma_buf = i2c_get_dma_safe_msg_buf(pd->msg, 8);
584 	if (pd->dma_buf)
585 		sh_mobile_i2c_xfer_dma(pd);
586 
587 	/* Enable all interrupts to begin with */
588 	iic_wr(pd, ICIC, ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
589 }
590 
poll_dte(struct sh_mobile_i2c_data * pd)591 static int poll_dte(struct sh_mobile_i2c_data *pd)
592 {
593 	int i;
594 
595 	for (i = 1000; i; i--) {
596 		u_int8_t val = iic_rd(pd, ICSR);
597 
598 		if (val & ICSR_DTE)
599 			break;
600 
601 		if (val & ICSR_TACK)
602 			return -ENXIO;
603 
604 		udelay(10);
605 	}
606 
607 	return i ? 0 : -ETIMEDOUT;
608 }
609 
poll_busy(struct sh_mobile_i2c_data * pd)610 static int poll_busy(struct sh_mobile_i2c_data *pd)
611 {
612 	int i;
613 
614 	for (i = 1000; i; i--) {
615 		u_int8_t val = iic_rd(pd, ICSR);
616 
617 		dev_dbg(pd->dev, "val 0x%02x pd->sr 0x%02x\n", val, pd->sr);
618 
619 		/* the interrupt handler may wake us up before the
620 		 * transfer is finished, so poll the hardware
621 		 * until we're done.
622 		 */
623 		if (!(val & ICSR_BUSY)) {
624 			/* handle missing acknowledge and arbitration lost */
625 			val |= pd->sr;
626 			if (val & ICSR_TACK)
627 				return -ENXIO;
628 			if (val & ICSR_AL)
629 				return -EAGAIN;
630 			break;
631 		}
632 
633 		udelay(10);
634 	}
635 
636 	return i ? 0 : -ETIMEDOUT;
637 }
638 
sh_mobile_xfer(struct sh_mobile_i2c_data * pd,struct i2c_msg * msgs,int num)639 static int sh_mobile_xfer(struct sh_mobile_i2c_data *pd,
640 			 struct i2c_msg *msgs, int num)
641 {
642 	struct i2c_msg	*msg;
643 	int err = 0;
644 	int i;
645 	long time_left;
646 
647 	/* Wake up device and enable clock */
648 	pm_runtime_get_sync(pd->dev);
649 
650 	/* Process all messages */
651 	for (i = 0; i < num; i++) {
652 		bool do_start = pd->send_stop || !i;
653 		msg = &msgs[i];
654 		pd->send_stop = i == num - 1 || msg->flags & I2C_M_STOP;
655 		pd->stop_after_dma = false;
656 
657 		start_ch(pd, msg, do_start);
658 
659 		if (do_start)
660 			i2c_op(pd, OP_START);
661 
662 		if (pd->atomic_xfer) {
663 			unsigned long j = jiffies + pd->adap.timeout;
664 
665 			time_left = time_before_eq(jiffies, j);
666 			while (time_left &&
667 			       !(pd->sr & (ICSR_TACK | SW_DONE))) {
668 				unsigned char sr = iic_rd(pd, ICSR);
669 
670 				if (sr & (ICSR_AL   | ICSR_TACK |
671 					  ICSR_WAIT | ICSR_DTE)) {
672 					sh_mobile_i2c_isr(0, pd);
673 					udelay(150);
674 				} else {
675 					cpu_relax();
676 				}
677 				time_left = time_before_eq(jiffies, j);
678 			}
679 		} else {
680 			/* The interrupt handler takes care of the rest... */
681 			time_left = wait_event_timeout(pd->wait,
682 					pd->sr & (ICSR_TACK | SW_DONE),
683 					pd->adap.timeout);
684 
685 			/* 'stop_after_dma' tells if DMA xfer was complete */
686 			i2c_put_dma_safe_msg_buf(pd->dma_buf, pd->msg,
687 						 pd->stop_after_dma);
688 		}
689 
690 		if (!time_left) {
691 			dev_err(pd->dev, "Transfer request timed out\n");
692 			if (pd->dma_direction != DMA_NONE)
693 				sh_mobile_i2c_cleanup_dma(pd, true);
694 
695 			err = -ETIMEDOUT;
696 			break;
697 		}
698 
699 		if (pd->send_stop)
700 			err = poll_busy(pd);
701 		else
702 			err = poll_dte(pd);
703 		if (err < 0)
704 			break;
705 	}
706 
707 	/* Disable channel */
708 	iic_wr(pd, ICCR, ICCR_SCP);
709 
710 	/* Disable clock and mark device as idle */
711 	pm_runtime_put_sync(pd->dev);
712 
713 	return err ?: num;
714 }
715 
sh_mobile_i2c_xfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)716 static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
717 			      struct i2c_msg *msgs,
718 			      int num)
719 {
720 	struct sh_mobile_i2c_data *pd = i2c_get_adapdata(adapter);
721 
722 	pd->atomic_xfer = false;
723 	return sh_mobile_xfer(pd, msgs, num);
724 }
725 
sh_mobile_i2c_xfer_atomic(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)726 static int sh_mobile_i2c_xfer_atomic(struct i2c_adapter *adapter,
727 				     struct i2c_msg *msgs,
728 				     int num)
729 {
730 	struct sh_mobile_i2c_data *pd = i2c_get_adapdata(adapter);
731 
732 	pd->atomic_xfer = true;
733 	return sh_mobile_xfer(pd, msgs, num);
734 }
735 
sh_mobile_i2c_func(struct i2c_adapter * adapter)736 static u32 sh_mobile_i2c_func(struct i2c_adapter *adapter)
737 {
738 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
739 }
740 
741 static const struct i2c_algorithm sh_mobile_i2c_algorithm = {
742 	.functionality = sh_mobile_i2c_func,
743 	.master_xfer = sh_mobile_i2c_xfer,
744 	.master_xfer_atomic = sh_mobile_i2c_xfer_atomic,
745 };
746 
747 static const struct i2c_adapter_quirks sh_mobile_i2c_quirks = {
748 	.flags = I2C_AQ_NO_ZERO_LEN_READ,
749 };
750 
751 /*
752  * r8a7740 has an errata regarding I2C I/O pad reset needing this workaround.
753  */
sh_mobile_i2c_r8a7740_workaround(struct sh_mobile_i2c_data * pd)754 static int sh_mobile_i2c_r8a7740_workaround(struct sh_mobile_i2c_data *pd)
755 {
756 	iic_set_clr(pd, ICCR, ICCR_ICE, 0);
757 	iic_rd(pd, ICCR); /* dummy read */
758 
759 	iic_set_clr(pd, ICSTART, ICSTART_ICSTART, 0);
760 	iic_rd(pd, ICSTART); /* dummy read */
761 
762 	udelay(10);
763 
764 	iic_wr(pd, ICCR, ICCR_SCP);
765 	iic_wr(pd, ICSTART, 0);
766 
767 	udelay(10);
768 
769 	iic_wr(pd, ICCR, ICCR_TRS);
770 	udelay(10);
771 	iic_wr(pd, ICCR, 0);
772 	udelay(10);
773 	iic_wr(pd, ICCR, ICCR_TRS);
774 	udelay(10);
775 
776 	return sh_mobile_i2c_init(pd);
777 }
778 
779 static const struct sh_mobile_dt_config default_dt_config = {
780 	.clks_per_count = 1,
781 	.setup = sh_mobile_i2c_init,
782 };
783 
784 static const struct sh_mobile_dt_config fast_clock_dt_config = {
785 	.clks_per_count = 2,
786 	.setup = sh_mobile_i2c_init,
787 };
788 
789 static const struct sh_mobile_dt_config v2_freq_calc_dt_config = {
790 	.clks_per_count = 2,
791 	.setup = sh_mobile_i2c_v2_init,
792 };
793 
794 static const struct sh_mobile_dt_config r8a7740_dt_config = {
795 	.clks_per_count = 1,
796 	.setup = sh_mobile_i2c_r8a7740_workaround,
797 };
798 
799 static const struct of_device_id sh_mobile_i2c_dt_ids[] = {
800 	{ .compatible = "renesas,iic-r8a73a4", .data = &fast_clock_dt_config },
801 	{ .compatible = "renesas,iic-r8a7740", .data = &r8a7740_dt_config },
802 	{ .compatible = "renesas,iic-r8a774c0", .data = &v2_freq_calc_dt_config },
803 	{ .compatible = "renesas,iic-r8a7790", .data = &v2_freq_calc_dt_config },
804 	{ .compatible = "renesas,iic-r8a7791", .data = &v2_freq_calc_dt_config },
805 	{ .compatible = "renesas,iic-r8a7792", .data = &v2_freq_calc_dt_config },
806 	{ .compatible = "renesas,iic-r8a7793", .data = &v2_freq_calc_dt_config },
807 	{ .compatible = "renesas,iic-r8a7794", .data = &v2_freq_calc_dt_config },
808 	{ .compatible = "renesas,iic-r8a7795", .data = &v2_freq_calc_dt_config },
809 	{ .compatible = "renesas,iic-r8a77990", .data = &v2_freq_calc_dt_config },
810 	{ .compatible = "renesas,iic-sh73a0", .data = &fast_clock_dt_config },
811 	{ .compatible = "renesas,rcar-gen2-iic", .data = &v2_freq_calc_dt_config },
812 	{ .compatible = "renesas,rcar-gen3-iic", .data = &v2_freq_calc_dt_config },
813 	{ .compatible = "renesas,rmobile-iic", .data = &default_dt_config },
814 	{},
815 };
816 MODULE_DEVICE_TABLE(of, sh_mobile_i2c_dt_ids);
817 
sh_mobile_i2c_release_dma(struct sh_mobile_i2c_data * pd)818 static void sh_mobile_i2c_release_dma(struct sh_mobile_i2c_data *pd)
819 {
820 	if (!IS_ERR(pd->dma_tx)) {
821 		dma_release_channel(pd->dma_tx);
822 		pd->dma_tx = ERR_PTR(-EPROBE_DEFER);
823 	}
824 
825 	if (!IS_ERR(pd->dma_rx)) {
826 		dma_release_channel(pd->dma_rx);
827 		pd->dma_rx = ERR_PTR(-EPROBE_DEFER);
828 	}
829 }
830 
sh_mobile_i2c_hook_irqs(struct platform_device * dev,struct sh_mobile_i2c_data * pd)831 static int sh_mobile_i2c_hook_irqs(struct platform_device *dev, struct sh_mobile_i2c_data *pd)
832 {
833 	struct device_node *np = dev_of_node(&dev->dev);
834 	int k = 0, ret;
835 
836 	if (np) {
837 		int irq;
838 
839 		while ((irq = platform_get_irq_optional(dev, k)) != -ENXIO) {
840 			if (irq < 0)
841 				return irq;
842 			ret = devm_request_irq(&dev->dev, irq, sh_mobile_i2c_isr,
843 					       0, dev_name(&dev->dev), pd);
844 			if (ret) {
845 				dev_err(&dev->dev, "cannot request IRQ %d\n", irq);
846 				return ret;
847 			}
848 			k++;
849 		}
850 	} else {
851 		struct resource *res;
852 		resource_size_t n;
853 
854 		while ((res = platform_get_resource(dev, IORESOURCE_IRQ, k))) {
855 			for (n = res->start; n <= res->end; n++) {
856 				ret = devm_request_irq(&dev->dev, n, sh_mobile_i2c_isr,
857 						       0, dev_name(&dev->dev), pd);
858 				if (ret) {
859 					dev_err(&dev->dev, "cannot request IRQ %pa\n", &n);
860 					return ret;
861 				}
862 			}
863 			k++;
864 		}
865 	}
866 
867 	return k > 0 ? 0 : -ENOENT;
868 }
869 
sh_mobile_i2c_probe(struct platform_device * dev)870 static int sh_mobile_i2c_probe(struct platform_device *dev)
871 {
872 	struct sh_mobile_i2c_data *pd;
873 	struct i2c_adapter *adap;
874 	const struct sh_mobile_dt_config *config;
875 	int ret;
876 	u32 bus_speed;
877 
878 	pd = devm_kzalloc(&dev->dev, sizeof(struct sh_mobile_i2c_data), GFP_KERNEL);
879 	if (!pd)
880 		return -ENOMEM;
881 
882 	pd->clk = devm_clk_get(&dev->dev, NULL);
883 	if (IS_ERR(pd->clk)) {
884 		dev_err(&dev->dev, "cannot get clock\n");
885 		return PTR_ERR(pd->clk);
886 	}
887 
888 	ret = sh_mobile_i2c_hook_irqs(dev, pd);
889 	if (ret)
890 		return ret;
891 
892 	pd->dev = &dev->dev;
893 	platform_set_drvdata(dev, pd);
894 
895 	pd->reg = devm_platform_get_and_ioremap_resource(dev, 0, &pd->res);
896 	if (IS_ERR(pd->reg))
897 		return PTR_ERR(pd->reg);
898 
899 	ret = of_property_read_u32(dev->dev.of_node, "clock-frequency", &bus_speed);
900 	pd->bus_speed = (ret || !bus_speed) ? I2C_MAX_STANDARD_MODE_FREQ : bus_speed;
901 	pd->clks_per_count = 1;
902 
903 	/* Newer variants come with two new bits in ICIC */
904 	if (resource_size(pd->res) > 0x17)
905 		pd->flags |= IIC_FLAG_HAS_ICIC67;
906 
907 	pm_runtime_enable(&dev->dev);
908 	pm_runtime_get_sync(&dev->dev);
909 
910 	config = of_device_get_match_data(&dev->dev);
911 	if (config) {
912 		pd->clks_per_count = config->clks_per_count;
913 		ret = config->setup(pd);
914 	} else {
915 		ret = sh_mobile_i2c_init(pd);
916 	}
917 
918 	pm_runtime_put_sync(&dev->dev);
919 	if (ret)
920 		return ret;
921 
922 	/* Init DMA */
923 	sg_init_table(&pd->sg, 1);
924 	pd->dma_direction = DMA_NONE;
925 	pd->dma_rx = pd->dma_tx = ERR_PTR(-EPROBE_DEFER);
926 
927 	/* setup the private data */
928 	adap = &pd->adap;
929 	i2c_set_adapdata(adap, pd);
930 
931 	adap->owner = THIS_MODULE;
932 	adap->algo = &sh_mobile_i2c_algorithm;
933 	adap->quirks = &sh_mobile_i2c_quirks;
934 	adap->dev.parent = &dev->dev;
935 	adap->retries = 5;
936 	adap->nr = dev->id;
937 	adap->dev.of_node = dev->dev.of_node;
938 
939 	strscpy(adap->name, dev->name, sizeof(adap->name));
940 
941 	spin_lock_init(&pd->lock);
942 	init_waitqueue_head(&pd->wait);
943 
944 	ret = i2c_add_numbered_adapter(adap);
945 	if (ret < 0) {
946 		sh_mobile_i2c_release_dma(pd);
947 		return ret;
948 	}
949 
950 	dev_info(&dev->dev, "I2C adapter %d, bus speed %lu Hz\n", adap->nr, pd->bus_speed);
951 
952 	return 0;
953 }
954 
sh_mobile_i2c_remove(struct platform_device * dev)955 static void sh_mobile_i2c_remove(struct platform_device *dev)
956 {
957 	struct sh_mobile_i2c_data *pd = platform_get_drvdata(dev);
958 
959 	i2c_del_adapter(&pd->adap);
960 	sh_mobile_i2c_release_dma(pd);
961 	pm_runtime_disable(&dev->dev);
962 }
963 
sh_mobile_i2c_suspend(struct device * dev)964 static int sh_mobile_i2c_suspend(struct device *dev)
965 {
966 	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
967 
968 	i2c_mark_adapter_suspended(&pd->adap);
969 	return 0;
970 }
971 
sh_mobile_i2c_resume(struct device * dev)972 static int sh_mobile_i2c_resume(struct device *dev)
973 {
974 	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
975 
976 	i2c_mark_adapter_resumed(&pd->adap);
977 	return 0;
978 }
979 
980 static const struct dev_pm_ops sh_mobile_i2c_pm_ops = {
981 	NOIRQ_SYSTEM_SLEEP_PM_OPS(sh_mobile_i2c_suspend,
982 				  sh_mobile_i2c_resume)
983 };
984 
985 static struct platform_driver sh_mobile_i2c_driver = {
986 	.driver		= {
987 		.name		= "i2c-sh_mobile",
988 		.of_match_table = sh_mobile_i2c_dt_ids,
989 		.pm	= pm_sleep_ptr(&sh_mobile_i2c_pm_ops),
990 	},
991 	.probe		= sh_mobile_i2c_probe,
992 	.remove_new	= sh_mobile_i2c_remove,
993 };
994 
sh_mobile_i2c_adap_init(void)995 static int __init sh_mobile_i2c_adap_init(void)
996 {
997 	return platform_driver_register(&sh_mobile_i2c_driver);
998 }
999 subsys_initcall(sh_mobile_i2c_adap_init);
1000 
sh_mobile_i2c_adap_exit(void)1001 static void __exit sh_mobile_i2c_adap_exit(void)
1002 {
1003 	platform_driver_unregister(&sh_mobile_i2c_driver);
1004 }
1005 module_exit(sh_mobile_i2c_adap_exit);
1006 
1007 MODULE_DESCRIPTION("SuperH Mobile I2C Bus Controller driver");
1008 MODULE_AUTHOR("Magnus Damm");
1009 MODULE_AUTHOR("Wolfram Sang");
1010 MODULE_LICENSE("GPL v2");
1011 MODULE_ALIAS("platform:i2c-sh_mobile");
1012