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Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa...
[deliverable/linux.git] / drivers / i2c / busses / i2c-mxs.c
1 /*
2 * Freescale MXS I2C bus driver
3 *
4 * Copyright (C) 2012-2013 Marek Vasut <marex@denx.de>
5 * Copyright (C) 2011-2012 Wolfram Sang, Pengutronix e.K.
6 *
7 * based on a (non-working) driver which was:
8 *
9 * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 */
17
18 #include <linux/slab.h>
19 #include <linux/device.h>
20 #include <linux/module.h>
21 #include <linux/i2c.h>
22 #include <linux/err.h>
23 #include <linux/interrupt.h>
24 #include <linux/completion.h>
25 #include <linux/platform_device.h>
26 #include <linux/jiffies.h>
27 #include <linux/io.h>
28 #include <linux/stmp_device.h>
29 #include <linux/of.h>
30 #include <linux/of_device.h>
31 #include <linux/dma-mapping.h>
32 #include <linux/dmaengine.h>
33
34 #define DRIVER_NAME "mxs-i2c"
35
36 #define MXS_I2C_CTRL0 (0x00)
37 #define MXS_I2C_CTRL0_SET (0x04)
38 #define MXS_I2C_CTRL0_CLR (0x08)
39
40 #define MXS_I2C_CTRL0_SFTRST 0x80000000
41 #define MXS_I2C_CTRL0_RUN 0x20000000
42 #define MXS_I2C_CTRL0_SEND_NAK_ON_LAST 0x02000000
43 #define MXS_I2C_CTRL0_PIO_MODE 0x01000000
44 #define MXS_I2C_CTRL0_RETAIN_CLOCK 0x00200000
45 #define MXS_I2C_CTRL0_POST_SEND_STOP 0x00100000
46 #define MXS_I2C_CTRL0_PRE_SEND_START 0x00080000
47 #define MXS_I2C_CTRL0_MASTER_MODE 0x00020000
48 #define MXS_I2C_CTRL0_DIRECTION 0x00010000
49 #define MXS_I2C_CTRL0_XFER_COUNT(v) ((v) & 0x0000FFFF)
50
51 #define MXS_I2C_TIMING0 (0x10)
52 #define MXS_I2C_TIMING1 (0x20)
53 #define MXS_I2C_TIMING2 (0x30)
54
55 #define MXS_I2C_CTRL1 (0x40)
56 #define MXS_I2C_CTRL1_SET (0x44)
57 #define MXS_I2C_CTRL1_CLR (0x48)
58
59 #define MXS_I2C_CTRL1_CLR_GOT_A_NAK 0x10000000
60 #define MXS_I2C_CTRL1_BUS_FREE_IRQ 0x80
61 #define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ 0x40
62 #define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ 0x20
63 #define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ 0x10
64 #define MXS_I2C_CTRL1_EARLY_TERM_IRQ 0x08
65 #define MXS_I2C_CTRL1_MASTER_LOSS_IRQ 0x04
66 #define MXS_I2C_CTRL1_SLAVE_STOP_IRQ 0x02
67 #define MXS_I2C_CTRL1_SLAVE_IRQ 0x01
68
69 #define MXS_I2C_STAT (0x50)
70 #define MXS_I2C_STAT_GOT_A_NAK 0x10000000
71 #define MXS_I2C_STAT_BUS_BUSY 0x00000800
72 #define MXS_I2C_STAT_CLK_GEN_BUSY 0x00000400
73
74 #define MXS_I2C_DATA(i2c) ((i2c->dev_type == MXS_I2C_V1) ? 0x60 : 0xa0)
75
76 #define MXS_I2C_DEBUG0_CLR(i2c) ((i2c->dev_type == MXS_I2C_V1) ? 0x78 : 0xb8)
77
78 #define MXS_I2C_DEBUG0_DMAREQ 0x80000000
79
80 #define MXS_I2C_IRQ_MASK (MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
81 MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
82 MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
83 MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
84 MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
85 MXS_I2C_CTRL1_SLAVE_IRQ)
86
87
88 #define MXS_CMD_I2C_SELECT (MXS_I2C_CTRL0_RETAIN_CLOCK | \
89 MXS_I2C_CTRL0_PRE_SEND_START | \
90 MXS_I2C_CTRL0_MASTER_MODE | \
91 MXS_I2C_CTRL0_DIRECTION | \
92 MXS_I2C_CTRL0_XFER_COUNT(1))
93
94 #define MXS_CMD_I2C_WRITE (MXS_I2C_CTRL0_PRE_SEND_START | \
95 MXS_I2C_CTRL0_MASTER_MODE | \
96 MXS_I2C_CTRL0_DIRECTION)
97
98 #define MXS_CMD_I2C_READ (MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
99 MXS_I2C_CTRL0_MASTER_MODE)
100
101 enum mxs_i2c_devtype {
102 MXS_I2C_UNKNOWN = 0,
103 MXS_I2C_V1,
104 MXS_I2C_V2,
105 };
106
107 /**
108 * struct mxs_i2c_dev - per device, private MXS-I2C data
109 *
110 * @dev: driver model device node
111 * @dev_type: distinguish i.MX23/i.MX28 features
112 * @regs: IO registers pointer
113 * @cmd_complete: completion object for transaction wait
114 * @cmd_err: error code for last transaction
115 * @adapter: i2c subsystem adapter node
116 */
117 struct mxs_i2c_dev {
118 struct device *dev;
119 enum mxs_i2c_devtype dev_type;
120 void __iomem *regs;
121 struct completion cmd_complete;
122 int cmd_err;
123 struct i2c_adapter adapter;
124
125 uint32_t timing0;
126 uint32_t timing1;
127 uint32_t timing2;
128
129 /* DMA support components */
130 struct dma_chan *dmach;
131 uint32_t pio_data[2];
132 uint32_t addr_data;
133 struct scatterlist sg_io[2];
134 bool dma_read;
135 };
136
137 static int mxs_i2c_reset(struct mxs_i2c_dev *i2c)
138 {
139 int ret = stmp_reset_block(i2c->regs);
140 if (ret)
141 return ret;
142
143 /*
144 * Configure timing for the I2C block. The I2C TIMING2 register has to
145 * be programmed with this particular magic number. The rest is derived
146 * from the XTAL speed and requested I2C speed.
147 *
148 * For details, see i.MX233 [25.4.2 - 25.4.4] and i.MX28 [27.5.2 - 27.5.4].
149 */
150 writel(i2c->timing0, i2c->regs + MXS_I2C_TIMING0);
151 writel(i2c->timing1, i2c->regs + MXS_I2C_TIMING1);
152 writel(i2c->timing2, i2c->regs + MXS_I2C_TIMING2);
153
154 writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
155
156 return 0;
157 }
158
159 static void mxs_i2c_dma_finish(struct mxs_i2c_dev *i2c)
160 {
161 if (i2c->dma_read) {
162 dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
163 dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
164 } else {
165 dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
166 }
167 }
168
169 static void mxs_i2c_dma_irq_callback(void *param)
170 {
171 struct mxs_i2c_dev *i2c = param;
172
173 complete(&i2c->cmd_complete);
174 mxs_i2c_dma_finish(i2c);
175 }
176
177 static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
178 struct i2c_msg *msg, uint32_t flags)
179 {
180 struct dma_async_tx_descriptor *desc;
181 struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
182
183 if (msg->flags & I2C_M_RD) {
184 i2c->dma_read = 1;
185 i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_READ;
186
187 /*
188 * SELECT command.
189 */
190
191 /* Queue the PIO register write transfer. */
192 i2c->pio_data[0] = MXS_CMD_I2C_SELECT;
193 desc = dmaengine_prep_slave_sg(i2c->dmach,
194 (struct scatterlist *)&i2c->pio_data[0],
195 1, DMA_TRANS_NONE, 0);
196 if (!desc) {
197 dev_err(i2c->dev,
198 "Failed to get PIO reg. write descriptor.\n");
199 goto select_init_pio_fail;
200 }
201
202 /* Queue the DMA data transfer. */
203 sg_init_one(&i2c->sg_io[0], &i2c->addr_data, 1);
204 dma_map_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
205 desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[0], 1,
206 DMA_MEM_TO_DEV,
207 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
208 if (!desc) {
209 dev_err(i2c->dev,
210 "Failed to get DMA data write descriptor.\n");
211 goto select_init_dma_fail;
212 }
213
214 /*
215 * READ command.
216 */
217
218 /* Queue the PIO register write transfer. */
219 i2c->pio_data[1] = flags | MXS_CMD_I2C_READ |
220 MXS_I2C_CTRL0_XFER_COUNT(msg->len);
221 desc = dmaengine_prep_slave_sg(i2c->dmach,
222 (struct scatterlist *)&i2c->pio_data[1],
223 1, DMA_TRANS_NONE, DMA_PREP_INTERRUPT);
224 if (!desc) {
225 dev_err(i2c->dev,
226 "Failed to get PIO reg. write descriptor.\n");
227 goto select_init_dma_fail;
228 }
229
230 /* Queue the DMA data transfer. */
231 sg_init_one(&i2c->sg_io[1], msg->buf, msg->len);
232 dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
233 desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1,
234 DMA_DEV_TO_MEM,
235 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
236 if (!desc) {
237 dev_err(i2c->dev,
238 "Failed to get DMA data write descriptor.\n");
239 goto read_init_dma_fail;
240 }
241 } else {
242 i2c->dma_read = 0;
243 i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_WRITE;
244
245 /*
246 * WRITE command.
247 */
248
249 /* Queue the PIO register write transfer. */
250 i2c->pio_data[0] = flags | MXS_CMD_I2C_WRITE |
251 MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1);
252 desc = dmaengine_prep_slave_sg(i2c->dmach,
253 (struct scatterlist *)&i2c->pio_data[0],
254 1, DMA_TRANS_NONE, 0);
255 if (!desc) {
256 dev_err(i2c->dev,
257 "Failed to get PIO reg. write descriptor.\n");
258 goto write_init_pio_fail;
259 }
260
261 /* Queue the DMA data transfer. */
262 sg_init_table(i2c->sg_io, 2);
263 sg_set_buf(&i2c->sg_io[0], &i2c->addr_data, 1);
264 sg_set_buf(&i2c->sg_io[1], msg->buf, msg->len);
265 dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
266 desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2,
267 DMA_MEM_TO_DEV,
268 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
269 if (!desc) {
270 dev_err(i2c->dev,
271 "Failed to get DMA data write descriptor.\n");
272 goto write_init_dma_fail;
273 }
274 }
275
276 /*
277 * The last descriptor must have this callback,
278 * to finish the DMA transaction.
279 */
280 desc->callback = mxs_i2c_dma_irq_callback;
281 desc->callback_param = i2c;
282
283 /* Start the transfer. */
284 dmaengine_submit(desc);
285 dma_async_issue_pending(i2c->dmach);
286 return 0;
287
288 /* Read failpath. */
289 read_init_dma_fail:
290 dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
291 select_init_dma_fail:
292 dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
293 select_init_pio_fail:
294 dmaengine_terminate_all(i2c->dmach);
295 return -EINVAL;
296
297 /* Write failpath. */
298 write_init_dma_fail:
299 dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
300 write_init_pio_fail:
301 dmaengine_terminate_all(i2c->dmach);
302 return -EINVAL;
303 }
304
305 static int mxs_i2c_pio_wait_xfer_end(struct mxs_i2c_dev *i2c)
306 {
307 unsigned long timeout = jiffies + msecs_to_jiffies(1000);
308
309 while (readl(i2c->regs + MXS_I2C_CTRL0) & MXS_I2C_CTRL0_RUN) {
310 if (time_after(jiffies, timeout))
311 return -ETIMEDOUT;
312 cond_resched();
313 }
314
315 return 0;
316 }
317
318 static int mxs_i2c_pio_check_error_state(struct mxs_i2c_dev *i2c)
319 {
320 u32 state;
321
322 state = readl(i2c->regs + MXS_I2C_CTRL1_CLR) & MXS_I2C_IRQ_MASK;
323
324 if (state & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
325 i2c->cmd_err = -ENXIO;
326 else if (state & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
327 MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
328 MXS_I2C_CTRL1_SLAVE_STOP_IRQ |
329 MXS_I2C_CTRL1_SLAVE_IRQ))
330 i2c->cmd_err = -EIO;
331
332 return i2c->cmd_err;
333 }
334
335 static void mxs_i2c_pio_trigger_cmd(struct mxs_i2c_dev *i2c, u32 cmd)
336 {
337 u32 reg;
338
339 writel(cmd, i2c->regs + MXS_I2C_CTRL0);
340
341 /* readback makes sure the write is latched into hardware */
342 reg = readl(i2c->regs + MXS_I2C_CTRL0);
343 reg |= MXS_I2C_CTRL0_RUN;
344 writel(reg, i2c->regs + MXS_I2C_CTRL0);
345 }
346
347 /*
348 * Start WRITE transaction on the I2C bus. By studying i.MX23 datasheet,
349 * CTRL0::PIO_MODE bit description clarifies the order in which the registers
350 * must be written during PIO mode operation. First, the CTRL0 register has
351 * to be programmed with all the necessary bits but the RUN bit. Then the
352 * payload has to be written into the DATA register. Finally, the transmission
353 * is executed by setting the RUN bit in CTRL0.
354 */
355 static void mxs_i2c_pio_trigger_write_cmd(struct mxs_i2c_dev *i2c, u32 cmd,
356 u32 data)
357 {
358 writel(cmd, i2c->regs + MXS_I2C_CTRL0);
359
360 if (i2c->dev_type == MXS_I2C_V1)
361 writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_SET);
362
363 writel(data, i2c->regs + MXS_I2C_DATA(i2c));
364 writel(MXS_I2C_CTRL0_RUN, i2c->regs + MXS_I2C_CTRL0_SET);
365 }
366
367 static int mxs_i2c_pio_setup_xfer(struct i2c_adapter *adap,
368 struct i2c_msg *msg, uint32_t flags)
369 {
370 struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
371 uint32_t addr_data = msg->addr << 1;
372 uint32_t data = 0;
373 int i, ret, xlen = 0, xmit = 0;
374 uint32_t start;
375
376 /* Mute IRQs coming from this block. */
377 writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_CLR);
378
379 /*
380 * MX23 idea:
381 * - Enable CTRL0::PIO_MODE (1 << 24)
382 * - Enable CTRL1::ACK_MODE (1 << 27)
383 *
384 * WARNING! The MX23 is broken in some way, even if it claims
385 * to support PIO, when we try to transfer any amount of data
386 * that is not aligned to 4 bytes, the DMA engine will have
387 * bits in DEBUG1::DMA_BYTES_ENABLES still set even after the
388 * transfer. This in turn will mess up the next transfer as
389 * the block it emit one byte write onto the bus terminated
390 * with a NAK+STOP. A possible workaround is to reset the IP
391 * block after every PIO transmission, which might just work.
392 *
393 * NOTE: The CTRL0::PIO_MODE description is important, since
394 * it outlines how the PIO mode is really supposed to work.
395 */
396 if (msg->flags & I2C_M_RD) {
397 /*
398 * PIO READ transfer:
399 *
400 * This transfer MUST be limited to 4 bytes maximum. It is not
401 * possible to transfer more than four bytes via PIO, since we
402 * can not in any way make sure we can read the data from the
403 * DATA register fast enough. Besides, the RX FIFO is only four
404 * bytes deep, thus we can only really read up to four bytes at
405 * time. Finally, there is no bit indicating us that new data
406 * arrived at the FIFO and can thus be fetched from the DATA
407 * register.
408 */
409 BUG_ON(msg->len > 4);
410
411 addr_data |= I2C_SMBUS_READ;
412
413 /* SELECT command. */
414 mxs_i2c_pio_trigger_write_cmd(i2c, MXS_CMD_I2C_SELECT,
415 addr_data);
416
417 ret = mxs_i2c_pio_wait_xfer_end(i2c);
418 if (ret) {
419 dev_err(i2c->dev,
420 "PIO: Failed to send SELECT command!\n");
421 goto cleanup;
422 }
423
424 /* READ command. */
425 mxs_i2c_pio_trigger_cmd(i2c,
426 MXS_CMD_I2C_READ | flags |
427 MXS_I2C_CTRL0_XFER_COUNT(msg->len));
428
429 ret = mxs_i2c_pio_wait_xfer_end(i2c);
430 if (ret) {
431 dev_err(i2c->dev,
432 "PIO: Failed to send SELECT command!\n");
433 goto cleanup;
434 }
435
436 data = readl(i2c->regs + MXS_I2C_DATA(i2c));
437 for (i = 0; i < msg->len; i++) {
438 msg->buf[i] = data & 0xff;
439 data >>= 8;
440 }
441 } else {
442 /*
443 * PIO WRITE transfer:
444 *
445 * The code below implements clock stretching to circumvent
446 * the possibility of kernel not being able to supply data
447 * fast enough. It is possible to transfer arbitrary amount
448 * of data using PIO write.
449 */
450 addr_data |= I2C_SMBUS_WRITE;
451
452 /*
453 * The LSB of data buffer is the first byte blasted across
454 * the bus. Higher order bytes follow. Thus the following
455 * filling schematic.
456 */
457
458 data = addr_data << 24;
459
460 /* Start the transfer with START condition. */
461 start = MXS_I2C_CTRL0_PRE_SEND_START;
462
463 /* If the transfer is long, use clock stretching. */
464 if (msg->len > 3)
465 start |= MXS_I2C_CTRL0_RETAIN_CLOCK;
466
467 for (i = 0; i < msg->len; i++) {
468 data >>= 8;
469 data |= (msg->buf[i] << 24);
470
471 xmit = 0;
472
473 /* This is the last transfer of the message. */
474 if (i + 1 == msg->len) {
475 /* Add optional STOP flag. */
476 start |= flags;
477 /* Remove RETAIN_CLOCK bit. */
478 start &= ~MXS_I2C_CTRL0_RETAIN_CLOCK;
479 xmit = 1;
480 }
481
482 /* Four bytes are ready in the "data" variable. */
483 if ((i & 3) == 2)
484 xmit = 1;
485
486 /* Nothing interesting happened, continue stuffing. */
487 if (!xmit)
488 continue;
489
490 /*
491 * Compute the size of the transfer and shift the
492 * data accordingly.
493 *
494 * i = (4k + 0) .... xlen = 2
495 * i = (4k + 1) .... xlen = 3
496 * i = (4k + 2) .... xlen = 4
497 * i = (4k + 3) .... xlen = 1
498 */
499
500 if ((i % 4) == 3)
501 xlen = 1;
502 else
503 xlen = (i % 4) + 2;
504
505 data >>= (4 - xlen) * 8;
506
507 dev_dbg(i2c->dev,
508 "PIO: len=%i pos=%i total=%i [W%s%s%s]\n",
509 xlen, i, msg->len,
510 start & MXS_I2C_CTRL0_PRE_SEND_START ? "S" : "",
511 start & MXS_I2C_CTRL0_POST_SEND_STOP ? "E" : "",
512 start & MXS_I2C_CTRL0_RETAIN_CLOCK ? "C" : "");
513
514 writel(MXS_I2C_DEBUG0_DMAREQ,
515 i2c->regs + MXS_I2C_DEBUG0_CLR(i2c));
516
517 mxs_i2c_pio_trigger_write_cmd(i2c,
518 start | MXS_I2C_CTRL0_MASTER_MODE |
519 MXS_I2C_CTRL0_DIRECTION |
520 MXS_I2C_CTRL0_XFER_COUNT(xlen), data);
521
522 /* The START condition is sent only once. */
523 start &= ~MXS_I2C_CTRL0_PRE_SEND_START;
524
525 /* Wait for the end of the transfer. */
526 ret = mxs_i2c_pio_wait_xfer_end(i2c);
527 if (ret) {
528 dev_err(i2c->dev,
529 "PIO: Failed to finish WRITE cmd!\n");
530 break;
531 }
532
533 /* Check NAK here. */
534 ret = readl(i2c->regs + MXS_I2C_STAT) &
535 MXS_I2C_STAT_GOT_A_NAK;
536 if (ret) {
537 ret = -ENXIO;
538 goto cleanup;
539 }
540 }
541 }
542
543 /* make sure we capture any occurred error into cmd_err */
544 ret = mxs_i2c_pio_check_error_state(i2c);
545
546 cleanup:
547 /* Clear any dangling IRQs and re-enable interrupts. */
548 writel(MXS_I2C_IRQ_MASK, i2c->regs + MXS_I2C_CTRL1_CLR);
549 writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
550
551 /* Clear the PIO_MODE on i.MX23 */
552 if (i2c->dev_type == MXS_I2C_V1)
553 writel(MXS_I2C_CTRL0_PIO_MODE, i2c->regs + MXS_I2C_CTRL0_CLR);
554
555 return ret;
556 }
557
558 /*
559 * Low level master read/write transaction.
560 */
561 static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
562 int stop)
563 {
564 struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
565 int ret;
566 int flags;
567 int use_pio = 0;
568
569 flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
570
571 dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
572 msg->addr, msg->len, msg->flags, stop);
573
574 if (msg->len == 0)
575 return -EINVAL;
576
577 /*
578 * The MX28 I2C IP block can only do PIO READ for transfer of to up
579 * 4 bytes of length. The write transfer is not limited as it can use
580 * clock stretching to avoid FIFO underruns.
581 */
582 if ((msg->flags & I2C_M_RD) && (msg->len <= 4))
583 use_pio = 1;
584 if (!(msg->flags & I2C_M_RD) && (msg->len < 7))
585 use_pio = 1;
586
587 i2c->cmd_err = 0;
588 if (use_pio) {
589 ret = mxs_i2c_pio_setup_xfer(adap, msg, flags);
590 /* No need to reset the block if NAK was received. */
591 if (ret && (ret != -ENXIO))
592 mxs_i2c_reset(i2c);
593 } else {
594 reinit_completion(&i2c->cmd_complete);
595 ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
596 if (ret)
597 return ret;
598
599 ret = wait_for_completion_timeout(&i2c->cmd_complete,
600 msecs_to_jiffies(1000));
601 if (ret == 0)
602 goto timeout;
603
604 ret = i2c->cmd_err;
605 }
606
607 if (ret == -ENXIO) {
608 /*
609 * If the transfer fails with a NAK from the slave the
610 * controller halts until it gets told to return to idle state.
611 */
612 writel(MXS_I2C_CTRL1_CLR_GOT_A_NAK,
613 i2c->regs + MXS_I2C_CTRL1_SET);
614 }
615
616 /*
617 * WARNING!
618 * The i.MX23 is strange. After each and every operation, it's I2C IP
619 * block must be reset, otherwise the IP block will misbehave. This can
620 * be observed on the bus by the block sending out one single byte onto
621 * the bus. In case such an error happens, bit 27 will be set in the
622 * DEBUG0 register. This bit is not documented in the i.MX23 datasheet
623 * and is marked as "TBD" instead. To reset this bit to a correct state,
624 * reset the whole block. Since the block reset does not take long, do
625 * reset the block after every transfer to play safe.
626 */
627 if (i2c->dev_type == MXS_I2C_V1)
628 mxs_i2c_reset(i2c);
629
630 dev_dbg(i2c->dev, "Done with err=%d\n", ret);
631
632 return ret;
633
634 timeout:
635 dev_dbg(i2c->dev, "Timeout!\n");
636 mxs_i2c_dma_finish(i2c);
637 ret = mxs_i2c_reset(i2c);
638 if (ret)
639 return ret;
640
641 return -ETIMEDOUT;
642 }
643
644 static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
645 int num)
646 {
647 int i;
648 int err;
649
650 for (i = 0; i < num; i++) {
651 err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
652 if (err)
653 return err;
654 }
655
656 return num;
657 }
658
659 static u32 mxs_i2c_func(struct i2c_adapter *adap)
660 {
661 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
662 }
663
664 static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
665 {
666 struct mxs_i2c_dev *i2c = dev_id;
667 u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
668
669 if (!stat)
670 return IRQ_NONE;
671
672 if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
673 i2c->cmd_err = -ENXIO;
674 else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
675 MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
676 MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
677 /* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
678 i2c->cmd_err = -EIO;
679
680 writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
681
682 return IRQ_HANDLED;
683 }
684
685 static const struct i2c_algorithm mxs_i2c_algo = {
686 .master_xfer = mxs_i2c_xfer,
687 .functionality = mxs_i2c_func,
688 };
689
690 static void mxs_i2c_derive_timing(struct mxs_i2c_dev *i2c, uint32_t speed)
691 {
692 /* The I2C block clock runs at 24MHz */
693 const uint32_t clk = 24000000;
694 uint32_t divider;
695 uint16_t high_count, low_count, rcv_count, xmit_count;
696 uint32_t bus_free, leadin;
697 struct device *dev = i2c->dev;
698
699 divider = DIV_ROUND_UP(clk, speed);
700
701 if (divider < 25) {
702 /*
703 * limit the divider, so that min(low_count, high_count)
704 * is >= 1
705 */
706 divider = 25;
707 dev_warn(dev,
708 "Speed too high (%u.%03u kHz), using %u.%03u kHz\n",
709 speed / 1000, speed % 1000,
710 clk / divider / 1000, clk / divider % 1000);
711 } else if (divider > 1897) {
712 /*
713 * limit the divider, so that max(low_count, high_count)
714 * cannot exceed 1023
715 */
716 divider = 1897;
717 dev_warn(dev,
718 "Speed too low (%u.%03u kHz), using %u.%03u kHz\n",
719 speed / 1000, speed % 1000,
720 clk / divider / 1000, clk / divider % 1000);
721 }
722
723 /*
724 * The I2C spec specifies the following timing data:
725 * standard mode fast mode Bitfield name
726 * tLOW (SCL LOW period) 4700 ns 1300 ns
727 * tHIGH (SCL HIGH period) 4000 ns 600 ns
728 * tSU;DAT (data setup time) 250 ns 100 ns
729 * tHD;STA (START hold time) 4000 ns 600 ns
730 * tBUF (bus free time) 4700 ns 1300 ns
731 *
732 * The hardware (of the i.MX28 at least) seems to add 2 additional
733 * clock cycles to the low_count and 7 cycles to the high_count.
734 * This is compensated for by subtracting the respective constants
735 * from the values written to the timing registers.
736 */
737 if (speed > 100000) {
738 /* fast mode */
739 low_count = DIV_ROUND_CLOSEST(divider * 13, (13 + 6));
740 high_count = DIV_ROUND_CLOSEST(divider * 6, (13 + 6));
741 leadin = DIV_ROUND_UP(600 * (clk / 1000000), 1000);
742 bus_free = DIV_ROUND_UP(1300 * (clk / 1000000), 1000);
743 } else {
744 /* normal mode */
745 low_count = DIV_ROUND_CLOSEST(divider * 47, (47 + 40));
746 high_count = DIV_ROUND_CLOSEST(divider * 40, (47 + 40));
747 leadin = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
748 bus_free = DIV_ROUND_UP(4700 * (clk / 1000000), 1000);
749 }
750 rcv_count = high_count * 3 / 8;
751 xmit_count = low_count * 3 / 8;
752
753 dev_dbg(dev,
754 "speed=%u(actual %u) divider=%u low=%u high=%u xmit=%u rcv=%u leadin=%u bus_free=%u\n",
755 speed, clk / divider, divider, low_count, high_count,
756 xmit_count, rcv_count, leadin, bus_free);
757
758 low_count -= 2;
759 high_count -= 7;
760 i2c->timing0 = (high_count << 16) | rcv_count;
761 i2c->timing1 = (low_count << 16) | xmit_count;
762 i2c->timing2 = (bus_free << 16 | leadin);
763 }
764
765 static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
766 {
767 uint32_t speed;
768 struct device *dev = i2c->dev;
769 struct device_node *node = dev->of_node;
770 int ret;
771
772 ret = of_property_read_u32(node, "clock-frequency", &speed);
773 if (ret) {
774 dev_warn(dev, "No I2C speed selected, using 100kHz\n");
775 speed = 100000;
776 }
777
778 mxs_i2c_derive_timing(i2c, speed);
779
780 return 0;
781 }
782
783 static struct platform_device_id mxs_i2c_devtype[] = {
784 {
785 .name = "imx23-i2c",
786 .driver_data = MXS_I2C_V1,
787 }, {
788 .name = "imx28-i2c",
789 .driver_data = MXS_I2C_V2,
790 }, { /* sentinel */ }
791 };
792 MODULE_DEVICE_TABLE(platform, mxs_i2c_devtype);
793
794 static const struct of_device_id mxs_i2c_dt_ids[] = {
795 { .compatible = "fsl,imx23-i2c", .data = &mxs_i2c_devtype[0], },
796 { .compatible = "fsl,imx28-i2c", .data = &mxs_i2c_devtype[1], },
797 { /* sentinel */ }
798 };
799 MODULE_DEVICE_TABLE(of, mxs_i2c_dt_ids);
800
801 static int mxs_i2c_probe(struct platform_device *pdev)
802 {
803 const struct of_device_id *of_id =
804 of_match_device(mxs_i2c_dt_ids, &pdev->dev);
805 struct device *dev = &pdev->dev;
806 struct mxs_i2c_dev *i2c;
807 struct i2c_adapter *adap;
808 struct resource *res;
809 int err, irq;
810
811 i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
812 if (!i2c)
813 return -ENOMEM;
814
815 if (of_id) {
816 const struct platform_device_id *device_id = of_id->data;
817 i2c->dev_type = device_id->driver_data;
818 }
819
820 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
821 i2c->regs = devm_ioremap_resource(&pdev->dev, res);
822 if (IS_ERR(i2c->regs))
823 return PTR_ERR(i2c->regs);
824
825 irq = platform_get_irq(pdev, 0);
826 if (irq < 0)
827 return irq;
828
829 err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
830 if (err)
831 return err;
832
833 i2c->dev = dev;
834
835 init_completion(&i2c->cmd_complete);
836
837 if (dev->of_node) {
838 err = mxs_i2c_get_ofdata(i2c);
839 if (err)
840 return err;
841 }
842
843 /* Setup the DMA */
844 i2c->dmach = dma_request_slave_channel(dev, "rx-tx");
845 if (!i2c->dmach) {
846 dev_err(dev, "Failed to request dma\n");
847 return -ENODEV;
848 }
849
850 platform_set_drvdata(pdev, i2c);
851
852 /* Do reset to enforce correct startup after pinmuxing */
853 err = mxs_i2c_reset(i2c);
854 if (err)
855 return err;
856
857 adap = &i2c->adapter;
858 strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
859 adap->owner = THIS_MODULE;
860 adap->algo = &mxs_i2c_algo;
861 adap->dev.parent = dev;
862 adap->nr = pdev->id;
863 adap->dev.of_node = pdev->dev.of_node;
864 i2c_set_adapdata(adap, i2c);
865 err = i2c_add_numbered_adapter(adap);
866 if (err) {
867 dev_err(dev, "Failed to add adapter (%d)\n", err);
868 writel(MXS_I2C_CTRL0_SFTRST,
869 i2c->regs + MXS_I2C_CTRL0_SET);
870 return err;
871 }
872
873 return 0;
874 }
875
876 static int mxs_i2c_remove(struct platform_device *pdev)
877 {
878 struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
879
880 i2c_del_adapter(&i2c->adapter);
881
882 if (i2c->dmach)
883 dma_release_channel(i2c->dmach);
884
885 writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
886
887 return 0;
888 }
889
890 static struct platform_driver mxs_i2c_driver = {
891 .driver = {
892 .name = DRIVER_NAME,
893 .owner = THIS_MODULE,
894 .of_match_table = mxs_i2c_dt_ids,
895 },
896 .probe = mxs_i2c_probe,
897 .remove = mxs_i2c_remove,
898 };
899
900 static int __init mxs_i2c_init(void)
901 {
902 return platform_driver_register(&mxs_i2c_driver);
903 }
904 subsys_initcall(mxs_i2c_init);
905
906 static void __exit mxs_i2c_exit(void)
907 {
908 platform_driver_unregister(&mxs_i2c_driver);
909 }
910 module_exit(mxs_i2c_exit);
911
912 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
913 MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
914 MODULE_DESCRIPTION("MXS I2C Bus Driver");
915 MODULE_LICENSE("GPL");
916 MODULE_ALIAS("platform:" DRIVER_NAME);
Linux kernel - Deliverables
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