1 /*
2 * Copyright (C) 2013 STMicroelectronics
3 *
4 * I2C master mode controller driver, used in STMicroelectronics devices.
5 *
6 * Author: Maxime Coquelin <maxime.coquelin@st.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2, as
10 * published by the Free Software Foundation.
11 */
12
13 #include <linux/clk.h>
14 #include <linux/delay.h>
15 #include <linux/err.h>
16 #include <linux/i2c.h>
17 #include <linux/interrupt.h>
18 #include <linux/io.h>
19 #include <linux/module.h>
20 #include <linux/of_address.h>
21 #include <linux/of_irq.h>
22 #include <linux/of.h>
23 #include <linux/pinctrl/consumer.h>
24 #include <linux/platform_device.h>
25
26 /* SSC registers */
27 #define SSC_BRG 0x000
28 #define SSC_TBUF 0x004
29 #define SSC_RBUF 0x008
30 #define SSC_CTL 0x00C
31 #define SSC_IEN 0x010
32 #define SSC_STA 0x014
33 #define SSC_I2C 0x018
34 #define SSC_SLAD 0x01C
35 #define SSC_REP_START_HOLD 0x020
36 #define SSC_START_HOLD 0x024
37 #define SSC_REP_START_SETUP 0x028
38 #define SSC_DATA_SETUP 0x02C
39 #define SSC_STOP_SETUP 0x030
40 #define SSC_BUS_FREE 0x034
41 #define SSC_TX_FSTAT 0x038
42 #define SSC_RX_FSTAT 0x03C
43 #define SSC_PRE_SCALER_BRG 0x040
44 #define SSC_CLR 0x080
45 #define SSC_NOISE_SUPP_WIDTH 0x100
46 #define SSC_PRSCALER 0x104
47 #define SSC_NOISE_SUPP_WIDTH_DATAOUT 0x108
48 #define SSC_PRSCALER_DATAOUT 0x10c
49
50 /* SSC Control */
51 #define SSC_CTL_DATA_WIDTH_9 0x8
52 #define SSC_CTL_DATA_WIDTH_MSK 0xf
53 #define SSC_CTL_BM 0xf
54 #define SSC_CTL_HB BIT(4)
55 #define SSC_CTL_PH BIT(5)
56 #define SSC_CTL_PO BIT(6)
57 #define SSC_CTL_SR BIT(7)
58 #define SSC_CTL_MS BIT(8)
59 #define SSC_CTL_EN BIT(9)
60 #define SSC_CTL_LPB BIT(10)
61 #define SSC_CTL_EN_TX_FIFO BIT(11)
62 #define SSC_CTL_EN_RX_FIFO BIT(12)
63 #define SSC_CTL_EN_CLST_RX BIT(13)
64
65 /* SSC Interrupt Enable */
66 #define SSC_IEN_RIEN BIT(0)
67 #define SSC_IEN_TIEN BIT(1)
68 #define SSC_IEN_TEEN BIT(2)
69 #define SSC_IEN_REEN BIT(3)
70 #define SSC_IEN_PEEN BIT(4)
71 #define SSC_IEN_AASEN BIT(6)
72 #define SSC_IEN_STOPEN BIT(7)
73 #define SSC_IEN_ARBLEN BIT(8)
74 #define SSC_IEN_NACKEN BIT(10)
75 #define SSC_IEN_REPSTRTEN BIT(11)
76 #define SSC_IEN_TX_FIFO_HALF BIT(12)
77 #define SSC_IEN_RX_FIFO_HALF_FULL BIT(14)
78
79 /* SSC Status */
80 #define SSC_STA_RIR BIT(0)
81 #define SSC_STA_TIR BIT(1)
82 #define SSC_STA_TE BIT(2)
83 #define SSC_STA_RE BIT(3)
84 #define SSC_STA_PE BIT(4)
85 #define SSC_STA_CLST BIT(5)
86 #define SSC_STA_AAS BIT(6)
87 #define SSC_STA_STOP BIT(7)
88 #define SSC_STA_ARBL BIT(8)
89 #define SSC_STA_BUSY BIT(9)
90 #define SSC_STA_NACK BIT(10)
91 #define SSC_STA_REPSTRT BIT(11)
92 #define SSC_STA_TX_FIFO_HALF BIT(12)
93 #define SSC_STA_TX_FIFO_FULL BIT(13)
94 #define SSC_STA_RX_FIFO_HALF BIT(14)
95
96 /* SSC I2C Control */
97 #define SSC_I2C_I2CM BIT(0)
98 #define SSC_I2C_STRTG BIT(1)
99 #define SSC_I2C_STOPG BIT(2)
100 #define SSC_I2C_ACKG BIT(3)
101 #define SSC_I2C_AD10 BIT(4)
102 #define SSC_I2C_TXENB BIT(5)
103 #define SSC_I2C_REPSTRTG BIT(11)
104 #define SSC_I2C_SLAVE_DISABLE BIT(12)
105
106 /* SSC Tx FIFO Status */
107 #define SSC_TX_FSTAT_STATUS 0x07
108
109 /* SSC Rx FIFO Status */
110 #define SSC_RX_FSTAT_STATUS 0x07
111
112 /* SSC Clear bit operation */
113 #define SSC_CLR_SSCAAS BIT(6)
114 #define SSC_CLR_SSCSTOP BIT(7)
115 #define SSC_CLR_SSCARBL BIT(8)
116 #define SSC_CLR_NACK BIT(10)
117 #define SSC_CLR_REPSTRT BIT(11)
118
119 /* SSC Clock Prescaler */
120 #define SSC_PRSC_VALUE 0x0f
121
122
123 #define SSC_TXFIFO_SIZE 0x8
124 #define SSC_RXFIFO_SIZE 0x8
125
126 enum st_i2c_mode {
127 I2C_MODE_STANDARD,
128 I2C_MODE_FAST,
129 I2C_MODE_END,
130 };
131
132 /**
133 * struct st_i2c_timings - per-Mode tuning parameters
134 * @rate: I2C bus rate
135 * @rep_start_hold: I2C repeated start hold time requirement
136 * @rep_start_setup: I2C repeated start set up time requirement
137 * @start_hold: I2C start hold time requirement
138 * @data_setup_time: I2C data set up time requirement
139 * @stop_setup_time: I2C stop set up time requirement
140 * @bus_free_time: I2C bus free time requirement
141 * @sda_pulse_min_limit: I2C SDA pulse mini width limit
142 */
143 struct st_i2c_timings {
144 u32 rate;
145 u32 rep_start_hold;
146 u32 rep_start_setup;
147 u32 start_hold;
148 u32 data_setup_time;
149 u32 stop_setup_time;
150 u32 bus_free_time;
151 u32 sda_pulse_min_limit;
152 };
153
154 /**
155 * struct st_i2c_client - client specific data
156 * @addr: 8-bit slave addr, including r/w bit
157 * @count: number of bytes to be transfered
158 * @xfered: number of bytes already transferred
159 * @buf: data buffer
160 * @result: result of the transfer
161 * @stop: last I2C msg to be sent, i.e. STOP to be generated
162 */
163 struct st_i2c_client {
164 u8 addr;
165 u32 count;
166 u32 xfered;
167 u8 *buf;
168 int result;
169 bool stop;
170 };
171
172 /**
173 * struct st_i2c_dev - private data of the controller
174 * @adap: I2C adapter for this controller
175 * @dev: device for this controller
176 * @base: virtual memory area
177 * @complete: completion of I2C message
178 * @irq: interrupt line for th controller
179 * @clk: hw ssc block clock
180 * @mode: I2C mode of the controller. Standard or Fast only supported
181 * @scl_min_width_us: SCL line minimum pulse width in us
182 * @sda_min_width_us: SDA line minimum pulse width in us
183 * @client: I2C transfert information
184 * @busy: I2C transfer on-going
185 */
186 struct st_i2c_dev {
187 struct i2c_adapter adap;
188 struct device *dev;
189 void __iomem *base;
190 struct completion complete;
191 int irq;
192 struct clk *clk;
193 int mode;
194 u32 scl_min_width_us;
195 u32 sda_min_width_us;
196 struct st_i2c_client client;
197 bool busy;
198 };
199
st_i2c_set_bits(void __iomem * reg,u32 mask)200 static inline void st_i2c_set_bits(void __iomem *reg, u32 mask)
201 {
202 writel_relaxed(readl_relaxed(reg) | mask, reg);
203 }
204
st_i2c_clr_bits(void __iomem * reg,u32 mask)205 static inline void st_i2c_clr_bits(void __iomem *reg, u32 mask)
206 {
207 writel_relaxed(readl_relaxed(reg) & ~mask, reg);
208 }
209
210 /*
211 * From I2C Specifications v0.5.
212 *
213 * All the values below have +10% margin added to be
214 * compatible with some out-of-spec devices,
215 * like HDMI link of the Toshiba 19AV600 TV.
216 */
217 static struct st_i2c_timings i2c_timings[] = {
218 [I2C_MODE_STANDARD] = {
219 .rate = 100000,
220 .rep_start_hold = 4400,
221 .rep_start_setup = 5170,
222 .start_hold = 4400,
223 .data_setup_time = 275,
224 .stop_setup_time = 4400,
225 .bus_free_time = 5170,
226 },
227 [I2C_MODE_FAST] = {
228 .rate = 400000,
229 .rep_start_hold = 660,
230 .rep_start_setup = 660,
231 .start_hold = 660,
232 .data_setup_time = 110,
233 .stop_setup_time = 660,
234 .bus_free_time = 1430,
235 },
236 };
237
st_i2c_flush_rx_fifo(struct st_i2c_dev * i2c_dev)238 static void st_i2c_flush_rx_fifo(struct st_i2c_dev *i2c_dev)
239 {
240 int count, i;
241
242 /*
243 * Counter only counts up to 7 but fifo size is 8...
244 * When fifo is full, counter is 0 and RIR bit of status register is
245 * set
246 */
247 if (readl_relaxed(i2c_dev->base + SSC_STA) & SSC_STA_RIR)
248 count = SSC_RXFIFO_SIZE;
249 else
250 count = readl_relaxed(i2c_dev->base + SSC_RX_FSTAT) &
251 SSC_RX_FSTAT_STATUS;
252
253 for (i = 0; i < count; i++)
254 readl_relaxed(i2c_dev->base + SSC_RBUF);
255 }
256
st_i2c_soft_reset(struct st_i2c_dev * i2c_dev)257 static void st_i2c_soft_reset(struct st_i2c_dev *i2c_dev)
258 {
259 /*
260 * FIFO needs to be emptied before reseting the IP,
261 * else the controller raises a BUSY error.
262 */
263 st_i2c_flush_rx_fifo(i2c_dev);
264
265 st_i2c_set_bits(i2c_dev->base + SSC_CTL, SSC_CTL_SR);
266 st_i2c_clr_bits(i2c_dev->base + SSC_CTL, SSC_CTL_SR);
267 }
268
269 /**
270 * st_i2c_hw_config() - Prepare SSC block, calculate and apply tuning timings
271 * @i2c_dev: Controller's private data
272 */
st_i2c_hw_config(struct st_i2c_dev * i2c_dev)273 static void st_i2c_hw_config(struct st_i2c_dev *i2c_dev)
274 {
275 unsigned long rate;
276 u32 val, ns_per_clk;
277 struct st_i2c_timings *t = &i2c_timings[i2c_dev->mode];
278
279 st_i2c_soft_reset(i2c_dev);
280
281 val = SSC_CLR_REPSTRT | SSC_CLR_NACK | SSC_CLR_SSCARBL |
282 SSC_CLR_SSCAAS | SSC_CLR_SSCSTOP;
283 writel_relaxed(val, i2c_dev->base + SSC_CLR);
284
285 /* SSC Control register setup */
286 val = SSC_CTL_PO | SSC_CTL_PH | SSC_CTL_HB | SSC_CTL_DATA_WIDTH_9;
287 writel_relaxed(val, i2c_dev->base + SSC_CTL);
288
289 rate = clk_get_rate(i2c_dev->clk);
290 ns_per_clk = 1000000000 / rate;
291
292 /* Baudrate */
293 val = rate / (2 * t->rate);
294 writel_relaxed(val, i2c_dev->base + SSC_BRG);
295
296 /* Pre-scaler baudrate */
297 writel_relaxed(1, i2c_dev->base + SSC_PRE_SCALER_BRG);
298
299 /* Enable I2C mode */
300 writel_relaxed(SSC_I2C_I2CM, i2c_dev->base + SSC_I2C);
301
302 /* Repeated start hold time */
303 val = t->rep_start_hold / ns_per_clk;
304 writel_relaxed(val, i2c_dev->base + SSC_REP_START_HOLD);
305
306 /* Repeated start set up time */
307 val = t->rep_start_setup / ns_per_clk;
308 writel_relaxed(val, i2c_dev->base + SSC_REP_START_SETUP);
309
310 /* Start hold time */
311 val = t->start_hold / ns_per_clk;
312 writel_relaxed(val, i2c_dev->base + SSC_START_HOLD);
313
314 /* Data set up time */
315 val = t->data_setup_time / ns_per_clk;
316 writel_relaxed(val, i2c_dev->base + SSC_DATA_SETUP);
317
318 /* Stop set up time */
319 val = t->stop_setup_time / ns_per_clk;
320 writel_relaxed(val, i2c_dev->base + SSC_STOP_SETUP);
321
322 /* Bus free time */
323 val = t->bus_free_time / ns_per_clk;
324 writel_relaxed(val, i2c_dev->base + SSC_BUS_FREE);
325
326 /* Prescalers set up */
327 val = rate / 10000000;
328 writel_relaxed(val, i2c_dev->base + SSC_PRSCALER);
329 writel_relaxed(val, i2c_dev->base + SSC_PRSCALER_DATAOUT);
330
331 /* Noise suppression witdh */
332 val = i2c_dev->scl_min_width_us * rate / 100000000;
333 writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH);
334
335 /* Noise suppression max output data delay width */
336 val = i2c_dev->sda_min_width_us * rate / 100000000;
337 writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH_DATAOUT);
338 }
339
st_i2c_recover_bus(struct i2c_adapter * i2c_adap)340 static int st_i2c_recover_bus(struct i2c_adapter *i2c_adap)
341 {
342 struct st_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
343 u32 ctl;
344
345 dev_dbg(i2c_dev->dev, "Trying to recover bus\n");
346
347 /*
348 * SSP IP is dual role SPI/I2C to generate 9 clock pulses
349 * we switch to SPI node, 9 bit words and write a 0. This
350 * has been validate with a oscilloscope and is easier
351 * than switching to GPIO mode.
352 */
353
354 /* Disable interrupts */
355 writel_relaxed(0, i2c_dev->base + SSC_IEN);
356
357 st_i2c_hw_config(i2c_dev);
358
359 ctl = SSC_CTL_EN | SSC_CTL_MS | SSC_CTL_EN_RX_FIFO | SSC_CTL_EN_TX_FIFO;
360 st_i2c_set_bits(i2c_dev->base + SSC_CTL, ctl);
361
362 st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM);
363 usleep_range(8000, 10000);
364
365 writel_relaxed(0, i2c_dev->base + SSC_TBUF);
366 usleep_range(2000, 4000);
367 st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM);
368
369 return 0;
370 }
371
st_i2c_wait_free_bus(struct st_i2c_dev * i2c_dev)372 static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev)
373 {
374 u32 sta;
375 int i, ret;
376
377 for (i = 0; i < 10; i++) {
378 sta = readl_relaxed(i2c_dev->base + SSC_STA);
379 if (!(sta & SSC_STA_BUSY))
380 return 0;
381
382 usleep_range(2000, 4000);
383 }
384
385 dev_err(i2c_dev->dev, "bus not free (status = 0x%08x)\n", sta);
386
387 ret = i2c_recover_bus(&i2c_dev->adap);
388 if (ret) {
389 dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret);
390 return ret;
391 }
392
393 return -EBUSY;
394 }
395
396 /**
397 * st_i2c_write_tx_fifo() - Write a byte in the Tx FIFO
398 * @i2c_dev: Controller's private data
399 * @byte: Data to write in the Tx FIFO
400 */
st_i2c_write_tx_fifo(struct st_i2c_dev * i2c_dev,u8 byte)401 static inline void st_i2c_write_tx_fifo(struct st_i2c_dev *i2c_dev, u8 byte)
402 {
403 u16 tbuf = byte << 1;
404
405 writel_relaxed(tbuf | 1, i2c_dev->base + SSC_TBUF);
406 }
407
408 /**
409 * st_i2c_wr_fill_tx_fifo() - Fill the Tx FIFO in write mode
410 * @i2c_dev: Controller's private data
411 *
412 * This functions fills the Tx FIFO with I2C transfert buffer when
413 * in write mode.
414 */
st_i2c_wr_fill_tx_fifo(struct st_i2c_dev * i2c_dev)415 static void st_i2c_wr_fill_tx_fifo(struct st_i2c_dev *i2c_dev)
416 {
417 struct st_i2c_client *c = &i2c_dev->client;
418 u32 tx_fstat, sta;
419 int i;
420
421 sta = readl_relaxed(i2c_dev->base + SSC_STA);
422 if (sta & SSC_STA_TX_FIFO_FULL)
423 return;
424
425 tx_fstat = readl_relaxed(i2c_dev->base + SSC_TX_FSTAT);
426 tx_fstat &= SSC_TX_FSTAT_STATUS;
427
428 if (c->count < (SSC_TXFIFO_SIZE - tx_fstat))
429 i = c->count;
430 else
431 i = SSC_TXFIFO_SIZE - tx_fstat;
432
433 for (; i > 0; i--, c->count--, c->buf++)
434 st_i2c_write_tx_fifo(i2c_dev, *c->buf);
435 }
436
437 /**
438 * st_i2c_rd_fill_tx_fifo() - Fill the Tx FIFO in read mode
439 * @i2c_dev: Controller's private data
440 *
441 * This functions fills the Tx FIFO with fixed pattern when
442 * in read mode to trigger clock.
443 */
st_i2c_rd_fill_tx_fifo(struct st_i2c_dev * i2c_dev,int max)444 static void st_i2c_rd_fill_tx_fifo(struct st_i2c_dev *i2c_dev, int max)
445 {
446 struct st_i2c_client *c = &i2c_dev->client;
447 u32 tx_fstat, sta;
448 int i;
449
450 sta = readl_relaxed(i2c_dev->base + SSC_STA);
451 if (sta & SSC_STA_TX_FIFO_FULL)
452 return;
453
454 tx_fstat = readl_relaxed(i2c_dev->base + SSC_TX_FSTAT);
455 tx_fstat &= SSC_TX_FSTAT_STATUS;
456
457 if (max < (SSC_TXFIFO_SIZE - tx_fstat))
458 i = max;
459 else
460 i = SSC_TXFIFO_SIZE - tx_fstat;
461
462 for (; i > 0; i--, c->xfered++)
463 st_i2c_write_tx_fifo(i2c_dev, 0xff);
464 }
465
st_i2c_read_rx_fifo(struct st_i2c_dev * i2c_dev)466 static void st_i2c_read_rx_fifo(struct st_i2c_dev *i2c_dev)
467 {
468 struct st_i2c_client *c = &i2c_dev->client;
469 u32 i, sta;
470 u16 rbuf;
471
472 sta = readl_relaxed(i2c_dev->base + SSC_STA);
473 if (sta & SSC_STA_RIR) {
474 i = SSC_RXFIFO_SIZE;
475 } else {
476 i = readl_relaxed(i2c_dev->base + SSC_RX_FSTAT);
477 i &= SSC_RX_FSTAT_STATUS;
478 }
479
480 for (; (i > 0) && (c->count > 0); i--, c->count--) {
481 rbuf = readl_relaxed(i2c_dev->base + SSC_RBUF) >> 1;
482 *c->buf++ = (u8)rbuf & 0xff;
483 }
484
485 if (i) {
486 dev_err(i2c_dev->dev, "Unexpected %d bytes in rx fifo\n", i);
487 st_i2c_flush_rx_fifo(i2c_dev);
488 }
489 }
490
491 /**
492 * st_i2c_terminate_xfer() - Send either STOP or REPSTART condition
493 * @i2c_dev: Controller's private data
494 */
st_i2c_terminate_xfer(struct st_i2c_dev * i2c_dev)495 static void st_i2c_terminate_xfer(struct st_i2c_dev *i2c_dev)
496 {
497 struct st_i2c_client *c = &i2c_dev->client;
498
499 st_i2c_clr_bits(i2c_dev->base + SSC_IEN, SSC_IEN_TEEN);
500 st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STRTG);
501
502 if (c->stop) {
503 st_i2c_set_bits(i2c_dev->base + SSC_IEN, SSC_IEN_STOPEN);
504 st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
505 } else {
506 st_i2c_set_bits(i2c_dev->base + SSC_IEN, SSC_IEN_REPSTRTEN);
507 st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_REPSTRTG);
508 }
509 }
510
511 /**
512 * st_i2c_handle_write() - Handle FIFO empty interrupt in case of write
513 * @i2c_dev: Controller's private data
514 */
st_i2c_handle_write(struct st_i2c_dev * i2c_dev)515 static void st_i2c_handle_write(struct st_i2c_dev *i2c_dev)
516 {
517 struct st_i2c_client *c = &i2c_dev->client;
518
519 st_i2c_flush_rx_fifo(i2c_dev);
520
521 if (!c->count)
522 /* End of xfer, send stop or repstart */
523 st_i2c_terminate_xfer(i2c_dev);
524 else
525 st_i2c_wr_fill_tx_fifo(i2c_dev);
526 }
527
528 /**
529 * st_i2c_handle_write() - Handle FIFO enmpty interrupt in case of read
530 * @i2c_dev: Controller's private data
531 */
st_i2c_handle_read(struct st_i2c_dev * i2c_dev)532 static void st_i2c_handle_read(struct st_i2c_dev *i2c_dev)
533 {
534 struct st_i2c_client *c = &i2c_dev->client;
535 u32 ien;
536
537 /* Trash the address read back */
538 if (!c->xfered) {
539 readl_relaxed(i2c_dev->base + SSC_RBUF);
540 st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_TXENB);
541 } else {
542 st_i2c_read_rx_fifo(i2c_dev);
543 }
544
545 if (!c->count) {
546 /* End of xfer, send stop or repstart */
547 st_i2c_terminate_xfer(i2c_dev);
548 } else if (c->count == 1) {
549 /* Penultimate byte to xfer, disable ACK gen. */
550 st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_ACKG);
551
552 /* Last received byte is to be handled by NACK interrupt */
553 ien = SSC_IEN_NACKEN | SSC_IEN_ARBLEN;
554 writel_relaxed(ien, i2c_dev->base + SSC_IEN);
555
556 st_i2c_rd_fill_tx_fifo(i2c_dev, c->count);
557 } else {
558 st_i2c_rd_fill_tx_fifo(i2c_dev, c->count - 1);
559 }
560 }
561
562 /**
563 * st_i2c_isr() - Interrupt routine
564 * @irq: interrupt number
565 * @data: Controller's private data
566 */
st_i2c_isr_thread(int irq,void * data)567 static irqreturn_t st_i2c_isr_thread(int irq, void *data)
568 {
569 struct st_i2c_dev *i2c_dev = data;
570 struct st_i2c_client *c = &i2c_dev->client;
571 u32 sta, ien;
572 int it;
573
574 ien = readl_relaxed(i2c_dev->base + SSC_IEN);
575 sta = readl_relaxed(i2c_dev->base + SSC_STA);
576
577 /* Use __fls() to check error bits first */
578 it = __fls(sta & ien);
579 if (it < 0) {
580 dev_dbg(i2c_dev->dev, "spurious it (sta=0x%04x, ien=0x%04x)\n",
581 sta, ien);
582 return IRQ_NONE;
583 }
584
585 switch (1 << it) {
586 case SSC_STA_TE:
587 if (c->addr & I2C_M_RD)
588 st_i2c_handle_read(i2c_dev);
589 else
590 st_i2c_handle_write(i2c_dev);
591 break;
592
593 case SSC_STA_STOP:
594 case SSC_STA_REPSTRT:
595 writel_relaxed(0, i2c_dev->base + SSC_IEN);
596 complete(&i2c_dev->complete);
597 break;
598
599 case SSC_STA_NACK:
600 writel_relaxed(SSC_CLR_NACK, i2c_dev->base + SSC_CLR);
601
602 /* Last received byte handled by NACK interrupt */
603 if ((c->addr & I2C_M_RD) && (c->count == 1) && (c->xfered)) {
604 st_i2c_handle_read(i2c_dev);
605 break;
606 }
607
608 it = SSC_IEN_STOPEN | SSC_IEN_ARBLEN;
609 writel_relaxed(it, i2c_dev->base + SSC_IEN);
610
611 st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
612 c->result = -EIO;
613 break;
614
615 case SSC_STA_ARBL:
616 writel_relaxed(SSC_CLR_SSCARBL, i2c_dev->base + SSC_CLR);
617
618 it = SSC_IEN_STOPEN | SSC_IEN_ARBLEN;
619 writel_relaxed(it, i2c_dev->base + SSC_IEN);
620
621 st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
622 c->result = -EAGAIN;
623 break;
624
625 default:
626 dev_err(i2c_dev->dev,
627 "it %d unhandled (sta=0x%04x)\n", it, sta);
628 }
629
630 /*
631 * Read IEN register to ensure interrupt mask write is effective
632 * before re-enabling interrupt at GIC level, and thus avoid spurious
633 * interrupts.
634 */
635 readl(i2c_dev->base + SSC_IEN);
636
637 return IRQ_HANDLED;
638 }
639
640 /**
641 * st_i2c_xfer_msg() - Transfer a single I2C message
642 * @i2c_dev: Controller's private data
643 * @msg: I2C message to transfer
644 * @is_first: first message of the sequence
645 * @is_last: last message of the sequence
646 */
st_i2c_xfer_msg(struct st_i2c_dev * i2c_dev,struct i2c_msg * msg,bool is_first,bool is_last)647 static int st_i2c_xfer_msg(struct st_i2c_dev *i2c_dev, struct i2c_msg *msg,
648 bool is_first, bool is_last)
649 {
650 struct st_i2c_client *c = &i2c_dev->client;
651 u32 ctl, i2c, it;
652 unsigned long timeout;
653 int ret;
654
655 c->addr = i2c_8bit_addr_from_msg(msg);
656 c->buf = msg->buf;
657 c->count = msg->len;
658 c->xfered = 0;
659 c->result = 0;
660 c->stop = is_last;
661
662 reinit_completion(&i2c_dev->complete);
663
664 ctl = SSC_CTL_EN | SSC_CTL_MS | SSC_CTL_EN_RX_FIFO | SSC_CTL_EN_TX_FIFO;
665 st_i2c_set_bits(i2c_dev->base + SSC_CTL, ctl);
666
667 i2c = SSC_I2C_TXENB;
668 if (c->addr & I2C_M_RD)
669 i2c |= SSC_I2C_ACKG;
670 st_i2c_set_bits(i2c_dev->base + SSC_I2C, i2c);
671
672 /* Write slave address */
673 st_i2c_write_tx_fifo(i2c_dev, c->addr);
674
675 /* Pre-fill Tx fifo with data in case of write */
676 if (!(c->addr & I2C_M_RD))
677 st_i2c_wr_fill_tx_fifo(i2c_dev);
678
679 it = SSC_IEN_NACKEN | SSC_IEN_TEEN | SSC_IEN_ARBLEN;
680 writel_relaxed(it, i2c_dev->base + SSC_IEN);
681
682 if (is_first) {
683 ret = st_i2c_wait_free_bus(i2c_dev);
684 if (ret)
685 return ret;
686
687 st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STRTG);
688 }
689
690 timeout = wait_for_completion_timeout(&i2c_dev->complete,
691 i2c_dev->adap.timeout);
692 ret = c->result;
693
694 if (!timeout) {
695 dev_err(i2c_dev->dev, "Write to slave 0x%x timed out\n",
696 c->addr);
697 ret = -ETIMEDOUT;
698 }
699
700 i2c = SSC_I2C_STOPG | SSC_I2C_REPSTRTG;
701 st_i2c_clr_bits(i2c_dev->base + SSC_I2C, i2c);
702
703 writel_relaxed(SSC_CLR_SSCSTOP | SSC_CLR_REPSTRT,
704 i2c_dev->base + SSC_CLR);
705
706 return ret;
707 }
708
709 /**
710 * st_i2c_xfer() - Transfer a single I2C message
711 * @i2c_adap: Adapter pointer to the controller
712 * @msgs: Pointer to data to be written.
713 * @num: Number of messages to be executed
714 */
st_i2c_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg msgs[],int num)715 static int st_i2c_xfer(struct i2c_adapter *i2c_adap,
716 struct i2c_msg msgs[], int num)
717 {
718 struct st_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
719 int ret, i;
720
721 i2c_dev->busy = true;
722
723 ret = clk_prepare_enable(i2c_dev->clk);
724 if (ret) {
725 dev_err(i2c_dev->dev, "Failed to prepare_enable clock\n");
726 return ret;
727 }
728
729 pinctrl_pm_select_default_state(i2c_dev->dev);
730
731 st_i2c_hw_config(i2c_dev);
732
733 for (i = 0; (i < num) && !ret; i++)
734 ret = st_i2c_xfer_msg(i2c_dev, &msgs[i], i == 0, i == num - 1);
735
736 pinctrl_pm_select_idle_state(i2c_dev->dev);
737
738 clk_disable_unprepare(i2c_dev->clk);
739
740 i2c_dev->busy = false;
741
742 return (ret < 0) ? ret : i;
743 }
744
745 #ifdef CONFIG_PM_SLEEP
st_i2c_suspend(struct device * dev)746 static int st_i2c_suspend(struct device *dev)
747 {
748 struct st_i2c_dev *i2c_dev = dev_get_drvdata(dev);
749
750 if (i2c_dev->busy)
751 return -EBUSY;
752
753 pinctrl_pm_select_sleep_state(dev);
754
755 return 0;
756 }
757
st_i2c_resume(struct device * dev)758 static int st_i2c_resume(struct device *dev)
759 {
760 pinctrl_pm_select_default_state(dev);
761 /* Go in idle state if available */
762 pinctrl_pm_select_idle_state(dev);
763
764 return 0;
765 }
766
767 static SIMPLE_DEV_PM_OPS(st_i2c_pm, st_i2c_suspend, st_i2c_resume);
768 #define ST_I2C_PM (&st_i2c_pm)
769 #else
770 #define ST_I2C_PM NULL
771 #endif
772
st_i2c_func(struct i2c_adapter * adap)773 static u32 st_i2c_func(struct i2c_adapter *adap)
774 {
775 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
776 }
777
778 static const struct i2c_algorithm st_i2c_algo = {
779 .master_xfer = st_i2c_xfer,
780 .functionality = st_i2c_func,
781 };
782
783 static struct i2c_bus_recovery_info st_i2c_recovery_info = {
784 .recover_bus = st_i2c_recover_bus,
785 };
786
st_i2c_of_get_deglitch(struct device_node * np,struct st_i2c_dev * i2c_dev)787 static int st_i2c_of_get_deglitch(struct device_node *np,
788 struct st_i2c_dev *i2c_dev)
789 {
790 int ret;
791
792 ret = of_property_read_u32(np, "st,i2c-min-scl-pulse-width-us",
793 &i2c_dev->scl_min_width_us);
794 if ((ret == -ENODATA) || (ret == -EOVERFLOW)) {
795 dev_err(i2c_dev->dev, "st,i2c-min-scl-pulse-width-us invalid\n");
796 return ret;
797 }
798
799 ret = of_property_read_u32(np, "st,i2c-min-sda-pulse-width-us",
800 &i2c_dev->sda_min_width_us);
801 if ((ret == -ENODATA) || (ret == -EOVERFLOW)) {
802 dev_err(i2c_dev->dev, "st,i2c-min-sda-pulse-width-us invalid\n");
803 return ret;
804 }
805
806 return 0;
807 }
808
st_i2c_probe(struct platform_device * pdev)809 static int st_i2c_probe(struct platform_device *pdev)
810 {
811 struct device_node *np = pdev->dev.of_node;
812 struct st_i2c_dev *i2c_dev;
813 struct resource *res;
814 u32 clk_rate;
815 struct i2c_adapter *adap;
816 int ret;
817
818 i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
819 if (!i2c_dev)
820 return -ENOMEM;
821
822 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
823 i2c_dev->base = devm_ioremap_resource(&pdev->dev, res);
824 if (IS_ERR(i2c_dev->base))
825 return PTR_ERR(i2c_dev->base);
826
827 i2c_dev->irq = irq_of_parse_and_map(np, 0);
828 if (!i2c_dev->irq) {
829 dev_err(&pdev->dev, "IRQ missing or invalid\n");
830 return -EINVAL;
831 }
832
833 i2c_dev->clk = of_clk_get_by_name(np, "ssc");
834 if (IS_ERR(i2c_dev->clk)) {
835 dev_err(&pdev->dev, "Unable to request clock\n");
836 return PTR_ERR(i2c_dev->clk);
837 }
838
839 i2c_dev->mode = I2C_MODE_STANDARD;
840 ret = of_property_read_u32(np, "clock-frequency", &clk_rate);
841 if ((!ret) && (clk_rate == 400000))
842 i2c_dev->mode = I2C_MODE_FAST;
843
844 i2c_dev->dev = &pdev->dev;
845
846 ret = devm_request_threaded_irq(&pdev->dev, i2c_dev->irq,
847 NULL, st_i2c_isr_thread,
848 IRQF_ONESHOT, pdev->name, i2c_dev);
849 if (ret) {
850 dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);
851 return ret;
852 }
853
854 pinctrl_pm_select_default_state(i2c_dev->dev);
855 /* In case idle state available, select it */
856 pinctrl_pm_select_idle_state(i2c_dev->dev);
857
858 ret = st_i2c_of_get_deglitch(np, i2c_dev);
859 if (ret)
860 return ret;
861
862 adap = &i2c_dev->adap;
863 i2c_set_adapdata(adap, i2c_dev);
864 snprintf(adap->name, sizeof(adap->name), "ST I2C(%pa)", &res->start);
865 adap->owner = THIS_MODULE;
866 adap->timeout = 2 * HZ;
867 adap->retries = 0;
868 adap->algo = &st_i2c_algo;
869 adap->bus_recovery_info = &st_i2c_recovery_info;
870 adap->dev.parent = &pdev->dev;
871 adap->dev.of_node = pdev->dev.of_node;
872
873 init_completion(&i2c_dev->complete);
874
875 ret = i2c_add_adapter(adap);
876 if (ret)
877 return ret;
878
879 platform_set_drvdata(pdev, i2c_dev);
880
881 dev_info(i2c_dev->dev, "%s initialized\n", adap->name);
882
883 return 0;
884 }
885
st_i2c_remove(struct platform_device * pdev)886 static int st_i2c_remove(struct platform_device *pdev)
887 {
888 struct st_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
889
890 i2c_del_adapter(&i2c_dev->adap);
891
892 return 0;
893 }
894
895 static const struct of_device_id st_i2c_match[] = {
896 { .compatible = "st,comms-ssc-i2c", },
897 { .compatible = "st,comms-ssc4-i2c", },
898 {},
899 };
900 MODULE_DEVICE_TABLE(of, st_i2c_match);
901
902 static struct platform_driver st_i2c_driver = {
903 .driver = {
904 .name = "st-i2c",
905 .of_match_table = st_i2c_match,
906 .pm = ST_I2C_PM,
907 },
908 .probe = st_i2c_probe,
909 .remove = st_i2c_remove,
910 };
911
912 module_platform_driver(st_i2c_driver);
913
914 MODULE_AUTHOR("Maxime Coquelin <maxime.coquelin@st.com>");
915 MODULE_DESCRIPTION("STMicroelectronics I2C driver");
916 MODULE_LICENSE("GPL v2");
917
