1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2007-2012 ST-Ericsson AB
4 * ST DDC I2C master mode driver, used in e.g. U300 series platforms.
5 * Author: Linus Walleij <linus.walleij@stericsson.com>
6 * Author: Jonas Aaberg <jonas.aberg@stericsson.com>
7 */
8 #include <linux/init.h>
9 #include <linux/module.h>
10 #include <linux/platform_device.h>
11 #include <linux/delay.h>
12 #include <linux/i2c.h>
13 #include <linux/spinlock.h>
14 #include <linux/completion.h>
15 #include <linux/err.h>
16 #include <linux/interrupt.h>
17 #include <linux/clk.h>
18 #include <linux/io.h>
19 #include <linux/slab.h>
20
21 /* the name of this kernel module */
22 #define NAME "stu300"
23
24 /* CR (Control Register) 8bit (R/W) */
25 #define I2C_CR (0x00000000)
26 #define I2C_CR_RESET_VALUE (0x00)
27 #define I2C_CR_RESET_UMASK (0x00)
28 #define I2C_CR_DDC1_ENABLE (0x80)
29 #define I2C_CR_TRANS_ENABLE (0x40)
30 #define I2C_CR_PERIPHERAL_ENABLE (0x20)
31 #define I2C_CR_DDC2B_ENABLE (0x10)
32 #define I2C_CR_START_ENABLE (0x08)
33 #define I2C_CR_ACK_ENABLE (0x04)
34 #define I2C_CR_STOP_ENABLE (0x02)
35 #define I2C_CR_INTERRUPT_ENABLE (0x01)
36 /* SR1 (Status Register 1) 8bit (R/-) */
37 #define I2C_SR1 (0x00000004)
38 #define I2C_SR1_RESET_VALUE (0x00)
39 #define I2C_SR1_RESET_UMASK (0x00)
40 #define I2C_SR1_EVF_IND (0x80)
41 #define I2C_SR1_ADD10_IND (0x40)
42 #define I2C_SR1_TRA_IND (0x20)
43 #define I2C_SR1_BUSY_IND (0x10)
44 #define I2C_SR1_BTF_IND (0x08)
45 #define I2C_SR1_ADSL_IND (0x04)
46 #define I2C_SR1_MSL_IND (0x02)
47 #define I2C_SR1_SB_IND (0x01)
48 /* SR2 (Status Register 2) 8bit (R/-) */
49 #define I2C_SR2 (0x00000008)
50 #define I2C_SR2_RESET_VALUE (0x00)
51 #define I2C_SR2_RESET_UMASK (0x40)
52 #define I2C_SR2_MASK (0xBF)
53 #define I2C_SR2_SCLFAL_IND (0x80)
54 #define I2C_SR2_ENDAD_IND (0x20)
55 #define I2C_SR2_AF_IND (0x10)
56 #define I2C_SR2_STOPF_IND (0x08)
57 #define I2C_SR2_ARLO_IND (0x04)
58 #define I2C_SR2_BERR_IND (0x02)
59 #define I2C_SR2_DDC2BF_IND (0x01)
60 /* CCR (Clock Control Register) 8bit (R/W) */
61 #define I2C_CCR (0x0000000C)
62 #define I2C_CCR_RESET_VALUE (0x00)
63 #define I2C_CCR_RESET_UMASK (0x00)
64 #define I2C_CCR_MASK (0xFF)
65 #define I2C_CCR_FMSM (0x80)
66 #define I2C_CCR_CC_MASK (0x7F)
67 /* OAR1 (Own Address Register 1) 8bit (R/W) */
68 #define I2C_OAR1 (0x00000010)
69 #define I2C_OAR1_RESET_VALUE (0x00)
70 #define I2C_OAR1_RESET_UMASK (0x00)
71 #define I2C_OAR1_ADD_MASK (0xFF)
72 /* OAR2 (Own Address Register 2) 8bit (R/W) */
73 #define I2C_OAR2 (0x00000014)
74 #define I2C_OAR2_RESET_VALUE (0x40)
75 #define I2C_OAR2_RESET_UMASK (0x19)
76 #define I2C_OAR2_MASK (0xE6)
77 #define I2C_OAR2_FR_25_10MHZ (0x00)
78 #define I2C_OAR2_FR_10_1667MHZ (0x20)
79 #define I2C_OAR2_FR_1667_2667MHZ (0x40)
80 #define I2C_OAR2_FR_2667_40MHZ (0x60)
81 #define I2C_OAR2_FR_40_5333MHZ (0x80)
82 #define I2C_OAR2_FR_5333_66MHZ (0xA0)
83 #define I2C_OAR2_FR_66_80MHZ (0xC0)
84 #define I2C_OAR2_FR_80_100MHZ (0xE0)
85 #define I2C_OAR2_FR_MASK (0xE0)
86 #define I2C_OAR2_ADD_MASK (0x06)
87 /* DR (Data Register) 8bit (R/W) */
88 #define I2C_DR (0x00000018)
89 #define I2C_DR_RESET_VALUE (0x00)
90 #define I2C_DR_RESET_UMASK (0xFF)
91 #define I2C_DR_D_MASK (0xFF)
92 /* ECCR (Extended Clock Control Register) 8bit (R/W) */
93 #define I2C_ECCR (0x0000001C)
94 #define I2C_ECCR_RESET_VALUE (0x00)
95 #define I2C_ECCR_RESET_UMASK (0xE0)
96 #define I2C_ECCR_MASK (0x1F)
97 #define I2C_ECCR_CC_MASK (0x1F)
98
99 /*
100 * These events are more or less responses to commands
101 * sent into the hardware, presumably reflecting the state
102 * of an internal state machine.
103 */
104 enum stu300_event {
105 STU300_EVENT_NONE = 0,
106 STU300_EVENT_1,
107 STU300_EVENT_2,
108 STU300_EVENT_3,
109 STU300_EVENT_4,
110 STU300_EVENT_5,
111 STU300_EVENT_6,
112 STU300_EVENT_7,
113 STU300_EVENT_8,
114 STU300_EVENT_9
115 };
116
117 enum stu300_error {
118 STU300_ERROR_NONE = 0,
119 STU300_ERROR_ACKNOWLEDGE_FAILURE,
120 STU300_ERROR_BUS_ERROR,
121 STU300_ERROR_ARBITRATION_LOST,
122 STU300_ERROR_UNKNOWN
123 };
124
125 /* timeout waiting for the controller to respond */
126 #define STU300_TIMEOUT (msecs_to_jiffies(1000))
127
128 /*
129 * The number of address send athemps tried before giving up.
130 * If the first one fails it seems like 5 to 8 attempts are required.
131 */
132 #define NUM_ADDR_RESEND_ATTEMPTS 12
133
134 /* I2C clock speed, in Hz 0-400kHz*/
135 static unsigned int scl_frequency = 100000;
136 module_param(scl_frequency, uint, 0644);
137
138 /**
139 * struct stu300_dev - the stu300 driver state holder
140 * @pdev: parent platform device
141 * @adapter: corresponding I2C adapter
142 * @clk: hardware block clock
143 * @irq: assigned interrupt line
144 * @cmd_issue_lock: this locks the following cmd_ variables
145 * @cmd_complete: acknowledge completion for an I2C command
146 * @cmd_event: expected event coming in as a response to a command
147 * @cmd_err: error code as response to a command
148 * @speed: current bus speed in Hz
149 * @msg_index: index of current message
150 * @msg_len: length of current message
151 */
152
153 struct stu300_dev {
154 struct platform_device *pdev;
155 struct i2c_adapter adapter;
156 void __iomem *virtbase;
157 struct clk *clk;
158 int irq;
159 spinlock_t cmd_issue_lock;
160 struct completion cmd_complete;
161 enum stu300_event cmd_event;
162 enum stu300_error cmd_err;
163 unsigned int speed;
164 int msg_index;
165 int msg_len;
166 };
167
168 /* Local forward function declarations */
169 static int stu300_init_hw(struct stu300_dev *dev);
170
171 /*
172 * The block needs writes in both MSW and LSW in order
173 * for all data lines to reach their destination.
174 */
stu300_wr8(u32 value,void __iomem * address)175 static inline void stu300_wr8(u32 value, void __iomem *address)
176 {
177 writel((value << 16) | value, address);
178 }
179
180 /*
181 * This merely masks off the duplicates which appear
182 * in bytes 1-3. You _MUST_ use 32-bit bus access on this
183 * device, else it will not work.
184 */
stu300_r8(void __iomem * address)185 static inline u32 stu300_r8(void __iomem *address)
186 {
187 return readl(address) & 0x000000FFU;
188 }
189
stu300_irq_enable(struct stu300_dev * dev)190 static void stu300_irq_enable(struct stu300_dev *dev)
191 {
192 u32 val;
193 val = stu300_r8(dev->virtbase + I2C_CR);
194 val |= I2C_CR_INTERRUPT_ENABLE;
195 /* Twice paranoia (possible HW glitch) */
196 stu300_wr8(val, dev->virtbase + I2C_CR);
197 stu300_wr8(val, dev->virtbase + I2C_CR);
198 }
199
stu300_irq_disable(struct stu300_dev * dev)200 static void stu300_irq_disable(struct stu300_dev *dev)
201 {
202 u32 val;
203 val = stu300_r8(dev->virtbase + I2C_CR);
204 val &= ~I2C_CR_INTERRUPT_ENABLE;
205 /* Twice paranoia (possible HW glitch) */
206 stu300_wr8(val, dev->virtbase + I2C_CR);
207 stu300_wr8(val, dev->virtbase + I2C_CR);
208 }
209
210
211 /*
212 * Tells whether a certain event or events occurred in
213 * response to a command. The events represent states in
214 * the internal state machine of the hardware. The events
215 * are not very well described in the hardware
216 * documentation and can only be treated as abstract state
217 * machine states.
218 *
219 * @ret 0 = event has not occurred or unknown error, any
220 * other value means the correct event occurred or an error.
221 */
222
stu300_event_occurred(struct stu300_dev * dev,enum stu300_event mr_event)223 static int stu300_event_occurred(struct stu300_dev *dev,
224 enum stu300_event mr_event) {
225 u32 status1;
226 u32 status2;
227
228 /* What event happened? */
229 status1 = stu300_r8(dev->virtbase + I2C_SR1);
230
231 if (!(status1 & I2C_SR1_EVF_IND))
232 /* No event at all */
233 return 0;
234
235 status2 = stu300_r8(dev->virtbase + I2C_SR2);
236
237 /* Block any multiple interrupts */
238 stu300_irq_disable(dev);
239
240 /* Check for errors first */
241 if (status2 & I2C_SR2_AF_IND) {
242 dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
243 return 1;
244 } else if (status2 & I2C_SR2_BERR_IND) {
245 dev->cmd_err = STU300_ERROR_BUS_ERROR;
246 return 1;
247 } else if (status2 & I2C_SR2_ARLO_IND) {
248 dev->cmd_err = STU300_ERROR_ARBITRATION_LOST;
249 return 1;
250 }
251
252 switch (mr_event) {
253 case STU300_EVENT_1:
254 if (status1 & I2C_SR1_ADSL_IND)
255 return 1;
256 break;
257 case STU300_EVENT_2:
258 case STU300_EVENT_3:
259 case STU300_EVENT_7:
260 case STU300_EVENT_8:
261 if (status1 & I2C_SR1_BTF_IND) {
262 return 1;
263 }
264 break;
265 case STU300_EVENT_4:
266 if (status2 & I2C_SR2_STOPF_IND)
267 return 1;
268 break;
269 case STU300_EVENT_5:
270 if (status1 & I2C_SR1_SB_IND)
271 /* Clear start bit */
272 return 1;
273 break;
274 case STU300_EVENT_6:
275 if (status2 & I2C_SR2_ENDAD_IND) {
276 /* First check for any errors */
277 return 1;
278 }
279 break;
280 case STU300_EVENT_9:
281 if (status1 & I2C_SR1_ADD10_IND)
282 return 1;
283 break;
284 default:
285 break;
286 }
287 /* If we get here, we're on thin ice.
288 * Here we are in a status where we have
289 * gotten a response that does not match
290 * what we requested.
291 */
292 dev->cmd_err = STU300_ERROR_UNKNOWN;
293 dev_err(&dev->pdev->dev,
294 "Unhandled interrupt! %d sr1: 0x%x sr2: 0x%x\n",
295 mr_event, status1, status2);
296 return 0;
297 }
298
stu300_irh(int irq,void * data)299 static irqreturn_t stu300_irh(int irq, void *data)
300 {
301 struct stu300_dev *dev = data;
302 int res;
303
304 /* Just make sure that the block is clocked */
305 clk_enable(dev->clk);
306
307 /* See if this was what we were waiting for */
308 spin_lock(&dev->cmd_issue_lock);
309
310 res = stu300_event_occurred(dev, dev->cmd_event);
311 if (res || dev->cmd_err != STU300_ERROR_NONE)
312 complete(&dev->cmd_complete);
313
314 spin_unlock(&dev->cmd_issue_lock);
315
316 clk_disable(dev->clk);
317
318 return IRQ_HANDLED;
319 }
320
321 /*
322 * Sends a command and then waits for the bits masked by *flagmask*
323 * to go high or low by IRQ awaiting.
324 */
stu300_start_and_await_event(struct stu300_dev * dev,u8 cr_value,enum stu300_event mr_event)325 static int stu300_start_and_await_event(struct stu300_dev *dev,
326 u8 cr_value,
327 enum stu300_event mr_event)
328 {
329 int ret;
330
331 /* Lock command issue, fill in an event we wait for */
332 spin_lock_irq(&dev->cmd_issue_lock);
333 init_completion(&dev->cmd_complete);
334 dev->cmd_err = STU300_ERROR_NONE;
335 dev->cmd_event = mr_event;
336 spin_unlock_irq(&dev->cmd_issue_lock);
337
338 /* Turn on interrupt, send command and wait. */
339 cr_value |= I2C_CR_INTERRUPT_ENABLE;
340 stu300_wr8(cr_value, dev->virtbase + I2C_CR);
341 ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
342 STU300_TIMEOUT);
343 if (ret < 0) {
344 dev_err(&dev->pdev->dev,
345 "wait_for_completion_interruptible_timeout() "
346 "returned %d waiting for event %04x\n", ret, mr_event);
347 return ret;
348 }
349
350 if (ret == 0) {
351 dev_err(&dev->pdev->dev, "controller timed out "
352 "waiting for event %d, reinit hardware\n", mr_event);
353 (void) stu300_init_hw(dev);
354 return -ETIMEDOUT;
355 }
356
357 if (dev->cmd_err != STU300_ERROR_NONE) {
358 dev_err(&dev->pdev->dev, "controller (start) "
359 "error %d waiting for event %d, reinit hardware\n",
360 dev->cmd_err, mr_event);
361 (void) stu300_init_hw(dev);
362 return -EIO;
363 }
364
365 return 0;
366 }
367
368 /*
369 * This waits for a flag to be set, if it is not set on entry, an interrupt is
370 * configured to wait for the flag using a completion.
371 */
stu300_await_event(struct stu300_dev * dev,enum stu300_event mr_event)372 static int stu300_await_event(struct stu300_dev *dev,
373 enum stu300_event mr_event)
374 {
375 int ret;
376
377 /* Is it already here? */
378 spin_lock_irq(&dev->cmd_issue_lock);
379 dev->cmd_err = STU300_ERROR_NONE;
380 dev->cmd_event = mr_event;
381
382 init_completion(&dev->cmd_complete);
383
384 /* Turn on the I2C interrupt for current operation */
385 stu300_irq_enable(dev);
386
387 /* Unlock the command block and wait for the event to occur */
388 spin_unlock_irq(&dev->cmd_issue_lock);
389
390 ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
391 STU300_TIMEOUT);
392 if (ret < 0) {
393 dev_err(&dev->pdev->dev,
394 "wait_for_completion_interruptible_timeout()"
395 "returned %d waiting for event %04x\n", ret, mr_event);
396 return ret;
397 }
398
399 if (ret == 0) {
400 if (mr_event != STU300_EVENT_6) {
401 dev_err(&dev->pdev->dev, "controller "
402 "timed out waiting for event %d, reinit "
403 "hardware\n", mr_event);
404 (void) stu300_init_hw(dev);
405 }
406 return -ETIMEDOUT;
407 }
408
409 if (dev->cmd_err != STU300_ERROR_NONE) {
410 if (mr_event != STU300_EVENT_6) {
411 dev_err(&dev->pdev->dev, "controller "
412 "error (await_event) %d waiting for event %d, "
413 "reinit hardware\n", dev->cmd_err, mr_event);
414 (void) stu300_init_hw(dev);
415 }
416 return -EIO;
417 }
418
419 return 0;
420 }
421
422 /*
423 * Waits for the busy bit to go low by repeated polling.
424 */
425 #define BUSY_RELEASE_ATTEMPTS 10
stu300_wait_while_busy(struct stu300_dev * dev)426 static int stu300_wait_while_busy(struct stu300_dev *dev)
427 {
428 unsigned long timeout;
429 int i;
430
431 for (i = 0; i < BUSY_RELEASE_ATTEMPTS; i++) {
432 timeout = jiffies + STU300_TIMEOUT;
433
434 while (!time_after(jiffies, timeout)) {
435 /* Is not busy? */
436 if ((stu300_r8(dev->virtbase + I2C_SR1) &
437 I2C_SR1_BUSY_IND) == 0)
438 return 0;
439 msleep(1);
440 }
441
442 dev_err(&dev->pdev->dev, "transaction timed out "
443 "waiting for device to be free (not busy). "
444 "Attempt: %d\n", i+1);
445
446 dev_err(&dev->pdev->dev, "base address = "
447 "0x%08x, reinit hardware\n", (u32) dev->virtbase);
448
449 (void) stu300_init_hw(dev);
450 }
451
452 dev_err(&dev->pdev->dev, "giving up after %d attempts "
453 "to reset the bus.\n", BUSY_RELEASE_ATTEMPTS);
454
455 return -ETIMEDOUT;
456 }
457
458 struct stu300_clkset {
459 unsigned long rate;
460 u32 setting;
461 };
462
463 static const struct stu300_clkset stu300_clktable[] = {
464 { 0, 0xFFU },
465 { 2500000, I2C_OAR2_FR_25_10MHZ },
466 { 10000000, I2C_OAR2_FR_10_1667MHZ },
467 { 16670000, I2C_OAR2_FR_1667_2667MHZ },
468 { 26670000, I2C_OAR2_FR_2667_40MHZ },
469 { 40000000, I2C_OAR2_FR_40_5333MHZ },
470 { 53330000, I2C_OAR2_FR_5333_66MHZ },
471 { 66000000, I2C_OAR2_FR_66_80MHZ },
472 { 80000000, I2C_OAR2_FR_80_100MHZ },
473 { 100000000, 0xFFU },
474 };
475
476
stu300_set_clk(struct stu300_dev * dev,unsigned long clkrate)477 static int stu300_set_clk(struct stu300_dev *dev, unsigned long clkrate)
478 {
479
480 u32 val;
481 int i = 0;
482
483 /* Locate the appropriate clock setting */
484 while (i < ARRAY_SIZE(stu300_clktable) - 1 &&
485 stu300_clktable[i].rate < clkrate)
486 i++;
487
488 if (stu300_clktable[i].setting == 0xFFU) {
489 dev_err(&dev->pdev->dev, "too %s clock rate requested "
490 "(%lu Hz).\n", i ? "high" : "low", clkrate);
491 return -EINVAL;
492 }
493
494 stu300_wr8(stu300_clktable[i].setting,
495 dev->virtbase + I2C_OAR2);
496
497 dev_dbg(&dev->pdev->dev, "Clock rate %lu Hz, I2C bus speed %d Hz "
498 "virtbase %p\n", clkrate, dev->speed, dev->virtbase);
499
500 if (dev->speed > 100000)
501 /* Fast Mode I2C */
502 val = ((clkrate/dev->speed) - 9)/3 + 1;
503 else
504 /* Standard Mode I2C */
505 val = ((clkrate/dev->speed) - 7)/2 + 1;
506
507 /* According to spec the divider must be > 2 */
508 if (val < 0x002) {
509 dev_err(&dev->pdev->dev, "too low clock rate (%lu Hz).\n",
510 clkrate);
511 return -EINVAL;
512 }
513
514 /* We have 12 bits clock divider only! */
515 if (val & 0xFFFFF000U) {
516 dev_err(&dev->pdev->dev, "too high clock rate (%lu Hz).\n",
517 clkrate);
518 return -EINVAL;
519 }
520
521 if (dev->speed > 100000) {
522 /* CC6..CC0 */
523 stu300_wr8((val & I2C_CCR_CC_MASK) | I2C_CCR_FMSM,
524 dev->virtbase + I2C_CCR);
525 dev_dbg(&dev->pdev->dev, "set clock divider to 0x%08x, "
526 "Fast Mode I2C\n", val);
527 } else {
528 /* CC6..CC0 */
529 stu300_wr8((val & I2C_CCR_CC_MASK),
530 dev->virtbase + I2C_CCR);
531 dev_dbg(&dev->pdev->dev, "set clock divider to "
532 "0x%08x, Standard Mode I2C\n", val);
533 }
534
535 /* CC11..CC7 */
536 stu300_wr8(((val >> 7) & 0x1F),
537 dev->virtbase + I2C_ECCR);
538
539 return 0;
540 }
541
542
stu300_init_hw(struct stu300_dev * dev)543 static int stu300_init_hw(struct stu300_dev *dev)
544 {
545 u32 dummy;
546 unsigned long clkrate;
547 int ret;
548
549 /* Disable controller */
550 stu300_wr8(0x00, dev->virtbase + I2C_CR);
551 /*
552 * Set own address to some default value (0x00).
553 * We do not support slave mode anyway.
554 */
555 stu300_wr8(0x00, dev->virtbase + I2C_OAR1);
556 /*
557 * The I2C controller only operates properly in 26 MHz but we
558 * program this driver as if we didn't know. This will also set the two
559 * high bits of the own address to zero as well.
560 * There is no known hardware issue with running in 13 MHz
561 * However, speeds over 200 kHz are not used.
562 */
563 clkrate = clk_get_rate(dev->clk);
564 ret = stu300_set_clk(dev, clkrate);
565
566 if (ret)
567 return ret;
568 /*
569 * Enable block, do it TWICE (hardware glitch)
570 * Setting bit 7 can enable DDC mode. (Not used currently.)
571 */
572 stu300_wr8(I2C_CR_PERIPHERAL_ENABLE,
573 dev->virtbase + I2C_CR);
574 stu300_wr8(I2C_CR_PERIPHERAL_ENABLE,
575 dev->virtbase + I2C_CR);
576 /* Make a dummy read of the status register SR1 & SR2 */
577 dummy = stu300_r8(dev->virtbase + I2C_SR2);
578 dummy = stu300_r8(dev->virtbase + I2C_SR1);
579
580 return 0;
581 }
582
583
584
585 /* Send slave address. */
stu300_send_address(struct stu300_dev * dev,struct i2c_msg * msg,int resend)586 static int stu300_send_address(struct stu300_dev *dev,
587 struct i2c_msg *msg, int resend)
588 {
589 u32 val;
590 int ret;
591
592 if (msg->flags & I2C_M_TEN) {
593 /* This is probably how 10 bit addresses look */
594 val = (0xf0 | (((u32) msg->addr & 0x300) >> 7)) &
595 I2C_DR_D_MASK;
596 if (msg->flags & I2C_M_RD)
597 /* This is the direction bit */
598 val |= 0x01;
599 } else {
600 val = i2c_8bit_addr_from_msg(msg);
601 }
602
603 if (resend) {
604 if (msg->flags & I2C_M_RD)
605 dev_dbg(&dev->pdev->dev, "read resend\n");
606 else
607 dev_dbg(&dev->pdev->dev, "write resend\n");
608 }
609
610 stu300_wr8(val, dev->virtbase + I2C_DR);
611
612 /* For 10bit addressing, await 10bit request (EVENT 9) */
613 if (msg->flags & I2C_M_TEN) {
614 ret = stu300_await_event(dev, STU300_EVENT_9);
615 /*
616 * The slave device wants a 10bit address, send the rest
617 * of the bits (the LSBits)
618 */
619 val = msg->addr & I2C_DR_D_MASK;
620 /* This clears "event 9" */
621 stu300_wr8(val, dev->virtbase + I2C_DR);
622 if (ret != 0)
623 return ret;
624 }
625 /* FIXME: Why no else here? two events for 10bit?
626 * Await event 6 (normal) or event 9 (10bit)
627 */
628
629 if (resend)
630 dev_dbg(&dev->pdev->dev, "await event 6\n");
631 ret = stu300_await_event(dev, STU300_EVENT_6);
632
633 /*
634 * Clear any pending EVENT 6 no matter what happened during
635 * await_event.
636 */
637 val = stu300_r8(dev->virtbase + I2C_CR);
638 val |= I2C_CR_PERIPHERAL_ENABLE;
639 stu300_wr8(val, dev->virtbase + I2C_CR);
640
641 return ret;
642 }
643
stu300_xfer_msg(struct i2c_adapter * adap,struct i2c_msg * msg,int stop)644 static int stu300_xfer_msg(struct i2c_adapter *adap,
645 struct i2c_msg *msg, int stop)
646 {
647 u32 cr;
648 u32 val;
649 u32 i;
650 int ret;
651 int attempts = 0;
652 struct stu300_dev *dev = i2c_get_adapdata(adap);
653
654 clk_enable(dev->clk);
655
656 /* Remove this if (0) to trace each and every message. */
657 if (0) {
658 dev_dbg(&dev->pdev->dev, "I2C message to: 0x%04x, len: %d, "
659 "flags: 0x%04x, stop: %d\n",
660 msg->addr, msg->len, msg->flags, stop);
661 }
662
663 /*
664 * For some reason, sending the address sometimes fails when running
665 * on the 13 MHz clock. No interrupt arrives. This is a work around,
666 * which tries to restart and send the address up to 10 times before
667 * really giving up. Usually 5 to 8 attempts are enough.
668 */
669 do {
670 if (attempts)
671 dev_dbg(&dev->pdev->dev, "wait while busy\n");
672 /* Check that the bus is free, or wait until some timeout */
673 ret = stu300_wait_while_busy(dev);
674 if (ret != 0)
675 goto exit_disable;
676
677 if (attempts)
678 dev_dbg(&dev->pdev->dev, "re-int hw\n");
679 /*
680 * According to ST, there is no problem if the clock is
681 * changed between 13 and 26 MHz during a transfer.
682 */
683 ret = stu300_init_hw(dev);
684 if (ret)
685 goto exit_disable;
686
687 /* Send a start condition */
688 cr = I2C_CR_PERIPHERAL_ENABLE;
689 /* Setting the START bit puts the block in master mode */
690 if (!(msg->flags & I2C_M_NOSTART))
691 cr |= I2C_CR_START_ENABLE;
692 if ((msg->flags & I2C_M_RD) && (msg->len > 1))
693 /* On read more than 1 byte, we need ack. */
694 cr |= I2C_CR_ACK_ENABLE;
695 /* Check that it gets through */
696 if (!(msg->flags & I2C_M_NOSTART)) {
697 if (attempts)
698 dev_dbg(&dev->pdev->dev, "send start event\n");
699 ret = stu300_start_and_await_event(dev, cr,
700 STU300_EVENT_5);
701 }
702
703 if (attempts)
704 dev_dbg(&dev->pdev->dev, "send address\n");
705
706 if (ret == 0)
707 /* Send address */
708 ret = stu300_send_address(dev, msg, attempts != 0);
709
710 if (ret != 0) {
711 attempts++;
712 dev_dbg(&dev->pdev->dev, "failed sending address, "
713 "retrying. Attempt: %d msg_index: %d/%d\n",
714 attempts, dev->msg_index, dev->msg_len);
715 }
716
717 } while (ret != 0 && attempts < NUM_ADDR_RESEND_ATTEMPTS);
718
719 if (attempts < NUM_ADDR_RESEND_ATTEMPTS && attempts > 0) {
720 dev_dbg(&dev->pdev->dev, "managed to get address "
721 "through after %d attempts\n", attempts);
722 } else if (attempts == NUM_ADDR_RESEND_ATTEMPTS) {
723 dev_dbg(&dev->pdev->dev, "I give up, tried %d times "
724 "to resend address.\n",
725 NUM_ADDR_RESEND_ATTEMPTS);
726 goto exit_disable;
727 }
728
729
730 if (msg->flags & I2C_M_RD) {
731 /* READ: we read the actual bytes one at a time */
732 for (i = 0; i < msg->len; i++) {
733 if (i == msg->len-1) {
734 /*
735 * Disable ACK and set STOP condition before
736 * reading last byte
737 */
738 val = I2C_CR_PERIPHERAL_ENABLE;
739
740 if (stop)
741 val |= I2C_CR_STOP_ENABLE;
742
743 stu300_wr8(val,
744 dev->virtbase + I2C_CR);
745 }
746 /* Wait for this byte... */
747 ret = stu300_await_event(dev, STU300_EVENT_7);
748 if (ret != 0)
749 goto exit_disable;
750 /* This clears event 7 */
751 msg->buf[i] = (u8) stu300_r8(dev->virtbase + I2C_DR);
752 }
753 } else {
754 /* WRITE: we send the actual bytes one at a time */
755 for (i = 0; i < msg->len; i++) {
756 /* Write the byte */
757 stu300_wr8(msg->buf[i],
758 dev->virtbase + I2C_DR);
759 /* Check status */
760 ret = stu300_await_event(dev, STU300_EVENT_8);
761 /* Next write to DR will clear event 8 */
762 if (ret != 0) {
763 dev_err(&dev->pdev->dev, "error awaiting "
764 "event 8 (%d)\n", ret);
765 goto exit_disable;
766 }
767 }
768 /* Check NAK */
769 if (!(msg->flags & I2C_M_IGNORE_NAK)) {
770 if (stu300_r8(dev->virtbase + I2C_SR2) &
771 I2C_SR2_AF_IND) {
772 dev_err(&dev->pdev->dev, "I2C payload "
773 "send returned NAK!\n");
774 ret = -EIO;
775 goto exit_disable;
776 }
777 }
778 if (stop) {
779 /* Send stop condition */
780 val = I2C_CR_PERIPHERAL_ENABLE;
781 val |= I2C_CR_STOP_ENABLE;
782 stu300_wr8(val, dev->virtbase + I2C_CR);
783 }
784 }
785
786 /* Check that the bus is free, or wait until some timeout occurs */
787 ret = stu300_wait_while_busy(dev);
788 if (ret != 0) {
789 dev_err(&dev->pdev->dev, "timeout waiting for transfer "
790 "to commence.\n");
791 goto exit_disable;
792 }
793
794 /* Dummy read status registers */
795 val = stu300_r8(dev->virtbase + I2C_SR2);
796 val = stu300_r8(dev->virtbase + I2C_SR1);
797 ret = 0;
798
799 exit_disable:
800 /* Disable controller */
801 stu300_wr8(0x00, dev->virtbase + I2C_CR);
802 clk_disable(dev->clk);
803 return ret;
804 }
805
stu300_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)806 static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
807 int num)
808 {
809 int ret = -1;
810 int i;
811
812 struct stu300_dev *dev = i2c_get_adapdata(adap);
813 dev->msg_len = num;
814
815 for (i = 0; i < num; i++) {
816 /*
817 * Another driver appears to send stop for each message,
818 * here we only do that for the last message. Possibly some
819 * peripherals require this behaviour, then their drivers
820 * have to send single messages in order to get "stop" for
821 * each message.
822 */
823 dev->msg_index = i;
824
825 ret = stu300_xfer_msg(adap, &msgs[i], (i == (num - 1)));
826
827 if (ret != 0) {
828 num = ret;
829 break;
830 }
831 }
832
833 return num;
834 }
835
stu300_xfer_todo(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)836 static int stu300_xfer_todo(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
837 {
838 /* TODO: implement polling for this case if need be. */
839 WARN(1, "%s: atomic transfers not implemented\n", dev_name(&adap->dev));
840 return -EOPNOTSUPP;
841 }
842
stu300_func(struct i2c_adapter * adap)843 static u32 stu300_func(struct i2c_adapter *adap)
844 {
845 /* This is the simplest thing you can think of... */
846 return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR;
847 }
848
849 static const struct i2c_algorithm stu300_algo = {
850 .master_xfer = stu300_xfer,
851 .master_xfer_atomic = stu300_xfer_todo,
852 .functionality = stu300_func,
853 };
854
855 static const struct i2c_adapter_quirks stu300_quirks = {
856 .flags = I2C_AQ_NO_ZERO_LEN,
857 };
858
stu300_probe(struct platform_device * pdev)859 static int stu300_probe(struct platform_device *pdev)
860 {
861 struct stu300_dev *dev;
862 struct i2c_adapter *adap;
863 struct resource *res;
864 int bus_nr;
865 int ret = 0;
866
867 dev = devm_kzalloc(&pdev->dev, sizeof(struct stu300_dev), GFP_KERNEL);
868 if (!dev)
869 return -ENOMEM;
870
871 bus_nr = pdev->id;
872 dev->clk = devm_clk_get(&pdev->dev, NULL);
873 if (IS_ERR(dev->clk)) {
874 dev_err(&pdev->dev, "could not retrieve i2c bus clock\n");
875 return PTR_ERR(dev->clk);
876 }
877
878 dev->pdev = pdev;
879 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
880 dev->virtbase = devm_ioremap_resource(&pdev->dev, res);
881 dev_dbg(&pdev->dev, "initialize bus device I2C%d on virtual "
882 "base %p\n", bus_nr, dev->virtbase);
883 if (IS_ERR(dev->virtbase))
884 return PTR_ERR(dev->virtbase);
885
886 dev->irq = platform_get_irq(pdev, 0);
887 ret = devm_request_irq(&pdev->dev, dev->irq, stu300_irh, 0, NAME, dev);
888 if (ret < 0)
889 return ret;
890
891 dev->speed = scl_frequency;
892
893 clk_prepare_enable(dev->clk);
894 ret = stu300_init_hw(dev);
895 clk_disable(dev->clk);
896 if (ret != 0) {
897 dev_err(&dev->pdev->dev, "error initializing hardware.\n");
898 return -EIO;
899 }
900
901 /* IRQ event handling initialization */
902 spin_lock_init(&dev->cmd_issue_lock);
903 dev->cmd_event = STU300_EVENT_NONE;
904 dev->cmd_err = STU300_ERROR_NONE;
905
906 adap = &dev->adapter;
907 adap->owner = THIS_MODULE;
908 /* DDC class but actually often used for more generic I2C */
909 adap->class = I2C_CLASS_DEPRECATED;
910 strlcpy(adap->name, "ST Microelectronics DDC I2C adapter",
911 sizeof(adap->name));
912 adap->nr = bus_nr;
913 adap->algo = &stu300_algo;
914 adap->dev.parent = &pdev->dev;
915 adap->dev.of_node = pdev->dev.of_node;
916 adap->quirks = &stu300_quirks;
917
918 i2c_set_adapdata(adap, dev);
919
920 /* i2c device drivers may be active on return from add_adapter() */
921 ret = i2c_add_numbered_adapter(adap);
922 if (ret)
923 return ret;
924
925 platform_set_drvdata(pdev, dev);
926 dev_info(&pdev->dev, "ST DDC I2C @ %p, irq %d\n",
927 dev->virtbase, dev->irq);
928
929 return 0;
930 }
931
932 #ifdef CONFIG_PM_SLEEP
stu300_suspend(struct device * device)933 static int stu300_suspend(struct device *device)
934 {
935 struct stu300_dev *dev = dev_get_drvdata(device);
936
937 /* Turn off everything */
938 stu300_wr8(0x00, dev->virtbase + I2C_CR);
939 return 0;
940 }
941
stu300_resume(struct device * device)942 static int stu300_resume(struct device *device)
943 {
944 int ret = 0;
945 struct stu300_dev *dev = dev_get_drvdata(device);
946
947 clk_enable(dev->clk);
948 ret = stu300_init_hw(dev);
949 clk_disable(dev->clk);
950
951 if (ret != 0)
952 dev_err(device, "error re-initializing hardware.\n");
953 return ret;
954 }
955
956 static SIMPLE_DEV_PM_OPS(stu300_pm, stu300_suspend, stu300_resume);
957 #define STU300_I2C_PM (&stu300_pm)
958 #else
959 #define STU300_I2C_PM NULL
960 #endif
961
stu300_remove(struct platform_device * pdev)962 static int stu300_remove(struct platform_device *pdev)
963 {
964 struct stu300_dev *dev = platform_get_drvdata(pdev);
965
966 i2c_del_adapter(&dev->adapter);
967 /* Turn off everything */
968 stu300_wr8(0x00, dev->virtbase + I2C_CR);
969 return 0;
970 }
971
972 static const struct of_device_id stu300_dt_match[] = {
973 { .compatible = "st,ddci2c" },
974 {},
975 };
976 MODULE_DEVICE_TABLE(of, stu300_dt_match);
977
978 static struct platform_driver stu300_i2c_driver = {
979 .driver = {
980 .name = NAME,
981 .pm = STU300_I2C_PM,
982 .of_match_table = stu300_dt_match,
983 },
984 .probe = stu300_probe,
985 .remove = stu300_remove,
986
987 };
988
stu300_init(void)989 static int __init stu300_init(void)
990 {
991 return platform_driver_register(&stu300_i2c_driver);
992 }
993
stu300_exit(void)994 static void __exit stu300_exit(void)
995 {
996 platform_driver_unregister(&stu300_i2c_driver);
997 }
998
999 /*
1000 * The systems using this bus often have very basic devices such
1001 * as regulators on the I2C bus, so this needs to be loaded early.
1002 * Therefore it is registered in the subsys_initcall().
1003 */
1004 subsys_initcall(stu300_init);
1005 module_exit(stu300_exit);
1006
1007 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
1008 MODULE_DESCRIPTION("ST Micro DDC I2C adapter (" NAME ")");
1009 MODULE_LICENSE("GPL");
1010 MODULE_ALIAS("platform:" NAME);
1011
