1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2009 ST-Ericsson SA
4 * Copyright (C) 2009 STMicroelectronics
5 *
6 * I2C master mode controller driver, used in Nomadik 8815
7 * and Ux500 platforms.
8 *
9 * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
10 * Author: Sachin Verma <sachin.verma@st.com>
11 */
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/amba/bus.h>
15 #include <linux/slab.h>
16 #include <linux/interrupt.h>
17 #include <linux/i2c.h>
18 #include <linux/err.h>
19 #include <linux/clk.h>
20 #include <linux/io.h>
21 #include <linux/pm_runtime.h>
22 #include <linux/of.h>
23 #include <linux/pinctrl/consumer.h>
24
25 #define DRIVER_NAME "nmk-i2c"
26
27 /* I2C Controller register offsets */
28 #define I2C_CR (0x000)
29 #define I2C_SCR (0x004)
30 #define I2C_HSMCR (0x008)
31 #define I2C_MCR (0x00C)
32 #define I2C_TFR (0x010)
33 #define I2C_SR (0x014)
34 #define I2C_RFR (0x018)
35 #define I2C_TFTR (0x01C)
36 #define I2C_RFTR (0x020)
37 #define I2C_DMAR (0x024)
38 #define I2C_BRCR (0x028)
39 #define I2C_IMSCR (0x02C)
40 #define I2C_RISR (0x030)
41 #define I2C_MISR (0x034)
42 #define I2C_ICR (0x038)
43
44 /* Control registers */
45 #define I2C_CR_PE (0x1 << 0) /* Peripheral Enable */
46 #define I2C_CR_OM (0x3 << 1) /* Operating mode */
47 #define I2C_CR_SAM (0x1 << 3) /* Slave addressing mode */
48 #define I2C_CR_SM (0x3 << 4) /* Speed mode */
49 #define I2C_CR_SGCM (0x1 << 6) /* Slave general call mode */
50 #define I2C_CR_FTX (0x1 << 7) /* Flush Transmit */
51 #define I2C_CR_FRX (0x1 << 8) /* Flush Receive */
52 #define I2C_CR_DMA_TX_EN (0x1 << 9) /* DMA Tx enable */
53 #define I2C_CR_DMA_RX_EN (0x1 << 10) /* DMA Rx Enable */
54 #define I2C_CR_DMA_SLE (0x1 << 11) /* DMA sync. logic enable */
55 #define I2C_CR_LM (0x1 << 12) /* Loopback mode */
56 #define I2C_CR_FON (0x3 << 13) /* Filtering on */
57 #define I2C_CR_FS (0x3 << 15) /* Force stop enable */
58
59 /* Master controller (MCR) register */
60 #define I2C_MCR_OP (0x1 << 0) /* Operation */
61 #define I2C_MCR_A7 (0x7f << 1) /* 7-bit address */
62 #define I2C_MCR_EA10 (0x7 << 8) /* 10-bit Extended address */
63 #define I2C_MCR_SB (0x1 << 11) /* Extended address */
64 #define I2C_MCR_AM (0x3 << 12) /* Address type */
65 #define I2C_MCR_STOP (0x1 << 14) /* Stop condition */
66 #define I2C_MCR_LENGTH (0x7ff << 15) /* Transaction length */
67
68 /* Status register (SR) */
69 #define I2C_SR_OP (0x3 << 0) /* Operation */
70 #define I2C_SR_STATUS (0x3 << 2) /* controller status */
71 #define I2C_SR_CAUSE (0x7 << 4) /* Abort cause */
72 #define I2C_SR_TYPE (0x3 << 7) /* Receive type */
73 #define I2C_SR_LENGTH (0x7ff << 9) /* Transfer length */
74
75 /* Interrupt mask set/clear (IMSCR) bits */
76 #define I2C_IT_TXFE (0x1 << 0)
77 #define I2C_IT_TXFNE (0x1 << 1)
78 #define I2C_IT_TXFF (0x1 << 2)
79 #define I2C_IT_TXFOVR (0x1 << 3)
80 #define I2C_IT_RXFE (0x1 << 4)
81 #define I2C_IT_RXFNF (0x1 << 5)
82 #define I2C_IT_RXFF (0x1 << 6)
83 #define I2C_IT_RFSR (0x1 << 16)
84 #define I2C_IT_RFSE (0x1 << 17)
85 #define I2C_IT_WTSR (0x1 << 18)
86 #define I2C_IT_MTD (0x1 << 19)
87 #define I2C_IT_STD (0x1 << 20)
88 #define I2C_IT_MAL (0x1 << 24)
89 #define I2C_IT_BERR (0x1 << 25)
90 #define I2C_IT_MTDWS (0x1 << 28)
91
92 #define GEN_MASK(val, mask, sb) (((val) << (sb)) & (mask))
93
94 /* some bits in ICR are reserved */
95 #define I2C_CLEAR_ALL_INTS 0x131f007f
96
97 /* first three msb bits are reserved */
98 #define IRQ_MASK(mask) (mask & 0x1fffffff)
99
100 /* maximum threshold value */
101 #define MAX_I2C_FIFO_THRESHOLD 15
102
103 enum i2c_freq_mode {
104 I2C_FREQ_MODE_STANDARD, /* up to 100 Kb/s */
105 I2C_FREQ_MODE_FAST, /* up to 400 Kb/s */
106 I2C_FREQ_MODE_HIGH_SPEED, /* up to 3.4 Mb/s */
107 I2C_FREQ_MODE_FAST_PLUS, /* up to 1 Mb/s */
108 };
109
110 /**
111 * struct i2c_vendor_data - per-vendor variations
112 * @has_mtdws: variant has the MTDWS bit
113 * @fifodepth: variant FIFO depth
114 */
115 struct i2c_vendor_data {
116 bool has_mtdws;
117 u32 fifodepth;
118 };
119
120 enum i2c_status {
121 I2C_NOP,
122 I2C_ON_GOING,
123 I2C_OK,
124 I2C_ABORT
125 };
126
127 /* operation */
128 enum i2c_operation {
129 I2C_NO_OPERATION = 0xff,
130 I2C_WRITE = 0x00,
131 I2C_READ = 0x01
132 };
133
134 /**
135 * struct i2c_nmk_client - client specific data
136 * @slave_adr: 7-bit slave address
137 * @count: no. bytes to be transferred
138 * @buffer: client data buffer
139 * @xfer_bytes: bytes transferred till now
140 * @operation: current I2C operation
141 */
142 struct i2c_nmk_client {
143 unsigned short slave_adr;
144 unsigned long count;
145 unsigned char *buffer;
146 unsigned long xfer_bytes;
147 enum i2c_operation operation;
148 };
149
150 /**
151 * struct nmk_i2c_dev - private data structure of the controller.
152 * @vendor: vendor data for this variant.
153 * @adev: parent amba device.
154 * @adap: corresponding I2C adapter.
155 * @irq: interrupt line for the controller.
156 * @virtbase: virtual io memory area.
157 * @clk: hardware i2c block clock.
158 * @cli: holder of client specific data.
159 * @clk_freq: clock frequency for the operation mode
160 * @tft: Tx FIFO Threshold in bytes
161 * @rft: Rx FIFO Threshold in bytes
162 * @timeout: Slave response timeout (ms)
163 * @sm: speed mode
164 * @stop: stop condition.
165 * @xfer_complete: acknowledge completion for a I2C message.
166 * @result: controller propogated result.
167 */
168 struct nmk_i2c_dev {
169 struct i2c_vendor_data *vendor;
170 struct amba_device *adev;
171 struct i2c_adapter adap;
172 int irq;
173 void __iomem *virtbase;
174 struct clk *clk;
175 struct i2c_nmk_client cli;
176 u32 clk_freq;
177 unsigned char tft;
178 unsigned char rft;
179 int timeout;
180 enum i2c_freq_mode sm;
181 int stop;
182 struct completion xfer_complete;
183 int result;
184 };
185
186 /* controller's abort causes */
187 static const char *abort_causes[] = {
188 "no ack received after address transmission",
189 "no ack received during data phase",
190 "ack received after xmission of master code",
191 "master lost arbitration",
192 "slave restarts",
193 "slave reset",
194 "overflow, maxsize is 2047 bytes",
195 };
196
i2c_set_bit(void __iomem * reg,u32 mask)197 static inline void i2c_set_bit(void __iomem *reg, u32 mask)
198 {
199 writel(readl(reg) | mask, reg);
200 }
201
i2c_clr_bit(void __iomem * reg,u32 mask)202 static inline void i2c_clr_bit(void __iomem *reg, u32 mask)
203 {
204 writel(readl(reg) & ~mask, reg);
205 }
206
207 /**
208 * flush_i2c_fifo() - This function flushes the I2C FIFO
209 * @dev: private data of I2C Driver
210 *
211 * This function flushes the I2C Tx and Rx FIFOs. It returns
212 * 0 on successful flushing of FIFO
213 */
flush_i2c_fifo(struct nmk_i2c_dev * dev)214 static int flush_i2c_fifo(struct nmk_i2c_dev *dev)
215 {
216 #define LOOP_ATTEMPTS 10
217 int i;
218 unsigned long timeout;
219
220 /*
221 * flush the transmit and receive FIFO. The flushing
222 * operation takes several cycles before to be completed.
223 * On the completion, the I2C internal logic clears these
224 * bits, until then no one must access Tx, Rx FIFO and
225 * should poll on these bits waiting for the completion.
226 */
227 writel((I2C_CR_FTX | I2C_CR_FRX), dev->virtbase + I2C_CR);
228
229 for (i = 0; i < LOOP_ATTEMPTS; i++) {
230 timeout = jiffies + dev->adap.timeout;
231
232 while (!time_after(jiffies, timeout)) {
233 if ((readl(dev->virtbase + I2C_CR) &
234 (I2C_CR_FTX | I2C_CR_FRX)) == 0)
235 return 0;
236 }
237 }
238
239 dev_err(&dev->adev->dev,
240 "flushing operation timed out giving up after %d attempts",
241 LOOP_ATTEMPTS);
242
243 return -ETIMEDOUT;
244 }
245
246 /**
247 * disable_all_interrupts() - Disable all interrupts of this I2c Bus
248 * @dev: private data of I2C Driver
249 */
disable_all_interrupts(struct nmk_i2c_dev * dev)250 static void disable_all_interrupts(struct nmk_i2c_dev *dev)
251 {
252 u32 mask = IRQ_MASK(0);
253 writel(mask, dev->virtbase + I2C_IMSCR);
254 }
255
256 /**
257 * clear_all_interrupts() - Clear all interrupts of I2C Controller
258 * @dev: private data of I2C Driver
259 */
clear_all_interrupts(struct nmk_i2c_dev * dev)260 static void clear_all_interrupts(struct nmk_i2c_dev *dev)
261 {
262 u32 mask;
263 mask = IRQ_MASK(I2C_CLEAR_ALL_INTS);
264 writel(mask, dev->virtbase + I2C_ICR);
265 }
266
267 /**
268 * init_hw() - initialize the I2C hardware
269 * @dev: private data of I2C Driver
270 */
init_hw(struct nmk_i2c_dev * dev)271 static int init_hw(struct nmk_i2c_dev *dev)
272 {
273 int stat;
274
275 stat = flush_i2c_fifo(dev);
276 if (stat)
277 goto exit;
278
279 /* disable the controller */
280 i2c_clr_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
281
282 disable_all_interrupts(dev);
283
284 clear_all_interrupts(dev);
285
286 dev->cli.operation = I2C_NO_OPERATION;
287
288 exit:
289 return stat;
290 }
291
292 /* enable peripheral, master mode operation */
293 #define DEFAULT_I2C_REG_CR ((1 << 1) | I2C_CR_PE)
294
295 /**
296 * load_i2c_mcr_reg() - load the MCR register
297 * @dev: private data of controller
298 * @flags: message flags
299 */
load_i2c_mcr_reg(struct nmk_i2c_dev * dev,u16 flags)300 static u32 load_i2c_mcr_reg(struct nmk_i2c_dev *dev, u16 flags)
301 {
302 u32 mcr = 0;
303 unsigned short slave_adr_3msb_bits;
304
305 mcr |= GEN_MASK(dev->cli.slave_adr, I2C_MCR_A7, 1);
306
307 if (unlikely(flags & I2C_M_TEN)) {
308 /* 10-bit address transaction */
309 mcr |= GEN_MASK(2, I2C_MCR_AM, 12);
310 /*
311 * Get the top 3 bits.
312 * EA10 represents extended address in MCR. This includes
313 * the extension (MSB bits) of the 7 bit address loaded
314 * in A7
315 */
316 slave_adr_3msb_bits = (dev->cli.slave_adr >> 7) & 0x7;
317
318 mcr |= GEN_MASK(slave_adr_3msb_bits, I2C_MCR_EA10, 8);
319 } else {
320 /* 7-bit address transaction */
321 mcr |= GEN_MASK(1, I2C_MCR_AM, 12);
322 }
323
324 /* start byte procedure not applied */
325 mcr |= GEN_MASK(0, I2C_MCR_SB, 11);
326
327 /* check the operation, master read/write? */
328 if (dev->cli.operation == I2C_WRITE)
329 mcr |= GEN_MASK(I2C_WRITE, I2C_MCR_OP, 0);
330 else
331 mcr |= GEN_MASK(I2C_READ, I2C_MCR_OP, 0);
332
333 /* stop or repeated start? */
334 if (dev->stop)
335 mcr |= GEN_MASK(1, I2C_MCR_STOP, 14);
336 else
337 mcr &= ~(GEN_MASK(1, I2C_MCR_STOP, 14));
338
339 mcr |= GEN_MASK(dev->cli.count, I2C_MCR_LENGTH, 15);
340
341 return mcr;
342 }
343
344 /**
345 * setup_i2c_controller() - setup the controller
346 * @dev: private data of controller
347 */
setup_i2c_controller(struct nmk_i2c_dev * dev)348 static void setup_i2c_controller(struct nmk_i2c_dev *dev)
349 {
350 u32 brcr1, brcr2;
351 u32 i2c_clk, div;
352 u32 ns;
353 u16 slsu;
354
355 writel(0x0, dev->virtbase + I2C_CR);
356 writel(0x0, dev->virtbase + I2C_HSMCR);
357 writel(0x0, dev->virtbase + I2C_TFTR);
358 writel(0x0, dev->virtbase + I2C_RFTR);
359 writel(0x0, dev->virtbase + I2C_DMAR);
360
361 i2c_clk = clk_get_rate(dev->clk);
362
363 /*
364 * set the slsu:
365 *
366 * slsu defines the data setup time after SCL clock
367 * stretching in terms of i2c clk cycles + 1 (zero means
368 * "wait one cycle"), the needed setup time for the three
369 * modes are 250ns, 100ns, 10ns respectively.
370 *
371 * As the time for one cycle T in nanoseconds is
372 * T = (1/f) * 1000000000 =>
373 * slsu = cycles / (1000000000 / f) + 1
374 */
375 ns = DIV_ROUND_UP_ULL(1000000000ULL, i2c_clk);
376 switch (dev->sm) {
377 case I2C_FREQ_MODE_FAST:
378 case I2C_FREQ_MODE_FAST_PLUS:
379 slsu = DIV_ROUND_UP(100, ns); /* Fast */
380 break;
381 case I2C_FREQ_MODE_HIGH_SPEED:
382 slsu = DIV_ROUND_UP(10, ns); /* High */
383 break;
384 case I2C_FREQ_MODE_STANDARD:
385 default:
386 slsu = DIV_ROUND_UP(250, ns); /* Standard */
387 break;
388 }
389 slsu += 1;
390
391 dev_dbg(&dev->adev->dev, "calculated SLSU = %04x\n", slsu);
392 writel(slsu << 16, dev->virtbase + I2C_SCR);
393
394 /*
395 * The spec says, in case of std. mode the divider is
396 * 2 whereas it is 3 for fast and fastplus mode of
397 * operation. TODO - high speed support.
398 */
399 div = (dev->clk_freq > I2C_MAX_STANDARD_MODE_FREQ) ? 3 : 2;
400
401 /*
402 * generate the mask for baud rate counters. The controller
403 * has two baud rate counters. One is used for High speed
404 * operation, and the other is for std, fast mode, fast mode
405 * plus operation. Currently we do not supprt high speed mode
406 * so set brcr1 to 0.
407 */
408 brcr1 = 0 << 16;
409 brcr2 = (i2c_clk/(dev->clk_freq * div)) & 0xffff;
410
411 /* set the baud rate counter register */
412 writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
413
414 /*
415 * set the speed mode. Currently we support
416 * only standard and fast mode of operation
417 * TODO - support for fast mode plus (up to 1Mb/s)
418 * and high speed (up to 3.4 Mb/s)
419 */
420 if (dev->sm > I2C_FREQ_MODE_FAST) {
421 dev_err(&dev->adev->dev,
422 "do not support this mode defaulting to std. mode\n");
423 brcr2 = i2c_clk / (I2C_MAX_STANDARD_MODE_FREQ * 2) & 0xffff;
424 writel((brcr1 | brcr2), dev->virtbase + I2C_BRCR);
425 writel(I2C_FREQ_MODE_STANDARD << 4,
426 dev->virtbase + I2C_CR);
427 }
428 writel(dev->sm << 4, dev->virtbase + I2C_CR);
429
430 /* set the Tx and Rx FIFO threshold */
431 writel(dev->tft, dev->virtbase + I2C_TFTR);
432 writel(dev->rft, dev->virtbase + I2C_RFTR);
433 }
434
435 /**
436 * read_i2c() - Read from I2C client device
437 * @dev: private data of I2C Driver
438 * @flags: message flags
439 *
440 * This function reads from i2c client device when controller is in
441 * master mode. There is a completion timeout. If there is no transfer
442 * before timeout error is returned.
443 */
read_i2c(struct nmk_i2c_dev * dev,u16 flags)444 static int read_i2c(struct nmk_i2c_dev *dev, u16 flags)
445 {
446 int status = 0;
447 u32 mcr, irq_mask;
448 unsigned long timeout;
449
450 mcr = load_i2c_mcr_reg(dev, flags);
451 writel(mcr, dev->virtbase + I2C_MCR);
452
453 /* load the current CR value */
454 writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
455 dev->virtbase + I2C_CR);
456
457 /* enable the controller */
458 i2c_set_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
459
460 init_completion(&dev->xfer_complete);
461
462 /* enable interrupts by setting the mask */
463 irq_mask = (I2C_IT_RXFNF | I2C_IT_RXFF |
464 I2C_IT_MAL | I2C_IT_BERR);
465
466 if (dev->stop || !dev->vendor->has_mtdws)
467 irq_mask |= I2C_IT_MTD;
468 else
469 irq_mask |= I2C_IT_MTDWS;
470
471 irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
472
473 writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
474 dev->virtbase + I2C_IMSCR);
475
476 timeout = wait_for_completion_timeout(
477 &dev->xfer_complete, dev->adap.timeout);
478
479 if (timeout == 0) {
480 /* Controller timed out */
481 dev_err(&dev->adev->dev, "read from slave 0x%x timed out\n",
482 dev->cli.slave_adr);
483 status = -ETIMEDOUT;
484 }
485 return status;
486 }
487
fill_tx_fifo(struct nmk_i2c_dev * dev,int no_bytes)488 static void fill_tx_fifo(struct nmk_i2c_dev *dev, int no_bytes)
489 {
490 int count;
491
492 for (count = (no_bytes - 2);
493 (count > 0) &&
494 (dev->cli.count != 0);
495 count--) {
496 /* write to the Tx FIFO */
497 writeb(*dev->cli.buffer,
498 dev->virtbase + I2C_TFR);
499 dev->cli.buffer++;
500 dev->cli.count--;
501 dev->cli.xfer_bytes++;
502 }
503
504 }
505
506 /**
507 * write_i2c() - Write data to I2C client.
508 * @dev: private data of I2C Driver
509 * @flags: message flags
510 *
511 * This function writes data to I2C client
512 */
write_i2c(struct nmk_i2c_dev * dev,u16 flags)513 static int write_i2c(struct nmk_i2c_dev *dev, u16 flags)
514 {
515 u32 status = 0;
516 u32 mcr, irq_mask;
517 unsigned long timeout;
518
519 mcr = load_i2c_mcr_reg(dev, flags);
520
521 writel(mcr, dev->virtbase + I2C_MCR);
522
523 /* load the current CR value */
524 writel(readl(dev->virtbase + I2C_CR) | DEFAULT_I2C_REG_CR,
525 dev->virtbase + I2C_CR);
526
527 /* enable the controller */
528 i2c_set_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
529
530 init_completion(&dev->xfer_complete);
531
532 /* enable interrupts by settings the masks */
533 irq_mask = (I2C_IT_TXFOVR | I2C_IT_MAL | I2C_IT_BERR);
534
535 /* Fill the TX FIFO with transmit data */
536 fill_tx_fifo(dev, MAX_I2C_FIFO_THRESHOLD);
537
538 if (dev->cli.count != 0)
539 irq_mask |= I2C_IT_TXFNE;
540
541 /*
542 * check if we want to transfer a single or multiple bytes, if so
543 * set the MTDWS bit (Master Transaction Done Without Stop)
544 * to start repeated start operation
545 */
546 if (dev->stop || !dev->vendor->has_mtdws)
547 irq_mask |= I2C_IT_MTD;
548 else
549 irq_mask |= I2C_IT_MTDWS;
550
551 irq_mask = I2C_CLEAR_ALL_INTS & IRQ_MASK(irq_mask);
552
553 writel(readl(dev->virtbase + I2C_IMSCR) | irq_mask,
554 dev->virtbase + I2C_IMSCR);
555
556 timeout = wait_for_completion_timeout(
557 &dev->xfer_complete, dev->adap.timeout);
558
559 if (timeout == 0) {
560 /* Controller timed out */
561 dev_err(&dev->adev->dev, "write to slave 0x%x timed out\n",
562 dev->cli.slave_adr);
563 status = -ETIMEDOUT;
564 }
565
566 return status;
567 }
568
569 /**
570 * nmk_i2c_xfer_one() - transmit a single I2C message
571 * @dev: device with a message encoded into it
572 * @flags: message flags
573 */
nmk_i2c_xfer_one(struct nmk_i2c_dev * dev,u16 flags)574 static int nmk_i2c_xfer_one(struct nmk_i2c_dev *dev, u16 flags)
575 {
576 int status;
577
578 if (flags & I2C_M_RD) {
579 /* read operation */
580 dev->cli.operation = I2C_READ;
581 status = read_i2c(dev, flags);
582 } else {
583 /* write operation */
584 dev->cli.operation = I2C_WRITE;
585 status = write_i2c(dev, flags);
586 }
587
588 if (status || (dev->result)) {
589 u32 i2c_sr;
590 u32 cause;
591
592 i2c_sr = readl(dev->virtbase + I2C_SR);
593 /*
594 * Check if the controller I2C operation status
595 * is set to ABORT(11b).
596 */
597 if (((i2c_sr >> 2) & 0x3) == 0x3) {
598 /* get the abort cause */
599 cause = (i2c_sr >> 4) & 0x7;
600 dev_err(&dev->adev->dev, "%s\n",
601 cause >= ARRAY_SIZE(abort_causes) ?
602 "unknown reason" :
603 abort_causes[cause]);
604 }
605
606 (void) init_hw(dev);
607
608 status = status ? status : dev->result;
609 }
610
611 return status;
612 }
613
614 /**
615 * nmk_i2c_xfer() - I2C transfer function used by kernel framework
616 * @i2c_adap: Adapter pointer to the controller
617 * @msgs: Pointer to data to be written.
618 * @num_msgs: Number of messages to be executed
619 *
620 * This is the function called by the generic kernel i2c_transfer()
621 * or i2c_smbus...() API calls. Note that this code is protected by the
622 * semaphore set in the kernel i2c_transfer() function.
623 *
624 * NOTE:
625 * READ TRANSFER : We impose a restriction of the first message to be the
626 * index message for any read transaction.
627 * - a no index is coded as '0',
628 * - 2byte big endian index is coded as '3'
629 * !!! msg[0].buf holds the actual index.
630 * This is compatible with generic messages of smbus emulator
631 * that send a one byte index.
632 * eg. a I2C transation to read 2 bytes from index 0
633 * idx = 0;
634 * msg[0].addr = client->addr;
635 * msg[0].flags = 0x0;
636 * msg[0].len = 1;
637 * msg[0].buf = &idx;
638 *
639 * msg[1].addr = client->addr;
640 * msg[1].flags = I2C_M_RD;
641 * msg[1].len = 2;
642 * msg[1].buf = rd_buff
643 * i2c_transfer(adap, msg, 2);
644 *
645 * WRITE TRANSFER : The I2C standard interface interprets all data as payload.
646 * If you want to emulate an SMBUS write transaction put the
647 * index as first byte(or first and second) in the payload.
648 * eg. a I2C transation to write 2 bytes from index 1
649 * wr_buff[0] = 0x1;
650 * wr_buff[1] = 0x23;
651 * wr_buff[2] = 0x46;
652 * msg[0].flags = 0x0;
653 * msg[0].len = 3;
654 * msg[0].buf = wr_buff;
655 * i2c_transfer(adap, msg, 1);
656 *
657 * To read or write a block of data (multiple bytes) using SMBUS emulation
658 * please use the i2c_smbus_read_i2c_block_data()
659 * or i2c_smbus_write_i2c_block_data() API
660 */
nmk_i2c_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg msgs[],int num_msgs)661 static int nmk_i2c_xfer(struct i2c_adapter *i2c_adap,
662 struct i2c_msg msgs[], int num_msgs)
663 {
664 int status = 0;
665 int i;
666 struct nmk_i2c_dev *dev = i2c_get_adapdata(i2c_adap);
667 int j;
668
669 pm_runtime_get_sync(&dev->adev->dev);
670
671 /* Attempt three times to send the message queue */
672 for (j = 0; j < 3; j++) {
673 /* setup the i2c controller */
674 setup_i2c_controller(dev);
675
676 for (i = 0; i < num_msgs; i++) {
677 dev->cli.slave_adr = msgs[i].addr;
678 dev->cli.buffer = msgs[i].buf;
679 dev->cli.count = msgs[i].len;
680 dev->stop = (i < (num_msgs - 1)) ? 0 : 1;
681 dev->result = 0;
682
683 status = nmk_i2c_xfer_one(dev, msgs[i].flags);
684 if (status != 0)
685 break;
686 }
687 if (status == 0)
688 break;
689 }
690
691 pm_runtime_put_sync(&dev->adev->dev);
692
693 /* return the no. messages processed */
694 if (status)
695 return status;
696 else
697 return num_msgs;
698 }
699
700 /**
701 * disable_interrupts() - disable the interrupts
702 * @dev: private data of controller
703 * @irq: interrupt number
704 */
disable_interrupts(struct nmk_i2c_dev * dev,u32 irq)705 static int disable_interrupts(struct nmk_i2c_dev *dev, u32 irq)
706 {
707 irq = IRQ_MASK(irq);
708 writel(readl(dev->virtbase + I2C_IMSCR) & ~(I2C_CLEAR_ALL_INTS & irq),
709 dev->virtbase + I2C_IMSCR);
710 return 0;
711 }
712
713 /**
714 * i2c_irq_handler() - interrupt routine
715 * @irq: interrupt number
716 * @arg: data passed to the handler
717 *
718 * This is the interrupt handler for the i2c driver. Currently
719 * it handles the major interrupts like Rx & Tx FIFO management
720 * interrupts, master transaction interrupts, arbitration and
721 * bus error interrupts. The rest of the interrupts are treated as
722 * unhandled.
723 */
i2c_irq_handler(int irq,void * arg)724 static irqreturn_t i2c_irq_handler(int irq, void *arg)
725 {
726 struct nmk_i2c_dev *dev = arg;
727 u32 tft, rft;
728 u32 count;
729 u32 misr, src;
730
731 /* load Tx FIFO and Rx FIFO threshold values */
732 tft = readl(dev->virtbase + I2C_TFTR);
733 rft = readl(dev->virtbase + I2C_RFTR);
734
735 /* read interrupt status register */
736 misr = readl(dev->virtbase + I2C_MISR);
737
738 src = __ffs(misr);
739 switch ((1 << src)) {
740
741 /* Transmit FIFO nearly empty interrupt */
742 case I2C_IT_TXFNE:
743 {
744 if (dev->cli.operation == I2C_READ) {
745 /*
746 * in read operation why do we care for writing?
747 * so disable the Transmit FIFO interrupt
748 */
749 disable_interrupts(dev, I2C_IT_TXFNE);
750 } else {
751 fill_tx_fifo(dev, (MAX_I2C_FIFO_THRESHOLD - tft));
752 /*
753 * if done, close the transfer by disabling the
754 * corresponding TXFNE interrupt
755 */
756 if (dev->cli.count == 0)
757 disable_interrupts(dev, I2C_IT_TXFNE);
758 }
759 }
760 break;
761
762 /*
763 * Rx FIFO nearly full interrupt.
764 * This is set when the numer of entries in Rx FIFO is
765 * greater or equal than the threshold value programmed
766 * in RFT
767 */
768 case I2C_IT_RXFNF:
769 for (count = rft; count > 0; count--) {
770 /* Read the Rx FIFO */
771 *dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
772 dev->cli.buffer++;
773 }
774 dev->cli.count -= rft;
775 dev->cli.xfer_bytes += rft;
776 break;
777
778 /* Rx FIFO full */
779 case I2C_IT_RXFF:
780 for (count = MAX_I2C_FIFO_THRESHOLD; count > 0; count--) {
781 *dev->cli.buffer = readb(dev->virtbase + I2C_RFR);
782 dev->cli.buffer++;
783 }
784 dev->cli.count -= MAX_I2C_FIFO_THRESHOLD;
785 dev->cli.xfer_bytes += MAX_I2C_FIFO_THRESHOLD;
786 break;
787
788 /* Master Transaction Done with/without stop */
789 case I2C_IT_MTD:
790 case I2C_IT_MTDWS:
791 if (dev->cli.operation == I2C_READ) {
792 while (!(readl(dev->virtbase + I2C_RISR)
793 & I2C_IT_RXFE)) {
794 if (dev->cli.count == 0)
795 break;
796 *dev->cli.buffer =
797 readb(dev->virtbase + I2C_RFR);
798 dev->cli.buffer++;
799 dev->cli.count--;
800 dev->cli.xfer_bytes++;
801 }
802 }
803
804 disable_all_interrupts(dev);
805 clear_all_interrupts(dev);
806
807 if (dev->cli.count) {
808 dev->result = -EIO;
809 dev_err(&dev->adev->dev,
810 "%lu bytes still remain to be xfered\n",
811 dev->cli.count);
812 (void) init_hw(dev);
813 }
814 complete(&dev->xfer_complete);
815
816 break;
817
818 /* Master Arbitration lost interrupt */
819 case I2C_IT_MAL:
820 dev->result = -EIO;
821 (void) init_hw(dev);
822
823 i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_MAL);
824 complete(&dev->xfer_complete);
825
826 break;
827
828 /*
829 * Bus Error interrupt.
830 * This happens when an unexpected start/stop condition occurs
831 * during the transaction.
832 */
833 case I2C_IT_BERR:
834 dev->result = -EIO;
835 /* get the status */
836 if (((readl(dev->virtbase + I2C_SR) >> 2) & 0x3) == I2C_ABORT)
837 (void) init_hw(dev);
838
839 i2c_set_bit(dev->virtbase + I2C_ICR, I2C_IT_BERR);
840 complete(&dev->xfer_complete);
841
842 break;
843
844 /*
845 * Tx FIFO overrun interrupt.
846 * This is set when a write operation in Tx FIFO is performed and
847 * the Tx FIFO is full.
848 */
849 case I2C_IT_TXFOVR:
850 dev->result = -EIO;
851 (void) init_hw(dev);
852
853 dev_err(&dev->adev->dev, "Tx Fifo Over run\n");
854 complete(&dev->xfer_complete);
855
856 break;
857
858 /* unhandled interrupts by this driver - TODO*/
859 case I2C_IT_TXFE:
860 case I2C_IT_TXFF:
861 case I2C_IT_RXFE:
862 case I2C_IT_RFSR:
863 case I2C_IT_RFSE:
864 case I2C_IT_WTSR:
865 case I2C_IT_STD:
866 dev_err(&dev->adev->dev, "unhandled Interrupt\n");
867 break;
868 default:
869 dev_err(&dev->adev->dev, "spurious Interrupt..\n");
870 break;
871 }
872
873 return IRQ_HANDLED;
874 }
875
nmk_i2c_suspend_late(struct device * dev)876 static int nmk_i2c_suspend_late(struct device *dev)
877 {
878 int ret;
879
880 ret = pm_runtime_force_suspend(dev);
881 if (ret)
882 return ret;
883
884 pinctrl_pm_select_sleep_state(dev);
885 return 0;
886 }
887
nmk_i2c_resume_early(struct device * dev)888 static int nmk_i2c_resume_early(struct device *dev)
889 {
890 return pm_runtime_force_resume(dev);
891 }
892
nmk_i2c_runtime_suspend(struct device * dev)893 static int nmk_i2c_runtime_suspend(struct device *dev)
894 {
895 struct amba_device *adev = to_amba_device(dev);
896 struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
897
898 clk_disable_unprepare(nmk_i2c->clk);
899 pinctrl_pm_select_idle_state(dev);
900 return 0;
901 }
902
nmk_i2c_runtime_resume(struct device * dev)903 static int nmk_i2c_runtime_resume(struct device *dev)
904 {
905 struct amba_device *adev = to_amba_device(dev);
906 struct nmk_i2c_dev *nmk_i2c = amba_get_drvdata(adev);
907 int ret;
908
909 ret = clk_prepare_enable(nmk_i2c->clk);
910 if (ret) {
911 dev_err(dev, "can't prepare_enable clock\n");
912 return ret;
913 }
914
915 pinctrl_pm_select_default_state(dev);
916
917 ret = init_hw(nmk_i2c);
918 if (ret) {
919 clk_disable_unprepare(nmk_i2c->clk);
920 pinctrl_pm_select_idle_state(dev);
921 }
922
923 return ret;
924 }
925
926 static const struct dev_pm_ops nmk_i2c_pm = {
927 LATE_SYSTEM_SLEEP_PM_OPS(nmk_i2c_suspend_late, nmk_i2c_resume_early)
928 RUNTIME_PM_OPS(nmk_i2c_runtime_suspend, nmk_i2c_runtime_resume, NULL)
929 };
930
nmk_i2c_functionality(struct i2c_adapter * adap)931 static unsigned int nmk_i2c_functionality(struct i2c_adapter *adap)
932 {
933 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
934 }
935
936 static const struct i2c_algorithm nmk_i2c_algo = {
937 .master_xfer = nmk_i2c_xfer,
938 .functionality = nmk_i2c_functionality
939 };
940
nmk_i2c_of_probe(struct device_node * np,struct nmk_i2c_dev * nmk)941 static void nmk_i2c_of_probe(struct device_node *np,
942 struct nmk_i2c_dev *nmk)
943 {
944 /* Default to 100 kHz if no frequency is given in the node */
945 if (of_property_read_u32(np, "clock-frequency", &nmk->clk_freq))
946 nmk->clk_freq = I2C_MAX_STANDARD_MODE_FREQ;
947
948 /* This driver only supports 'standard' and 'fast' modes of operation. */
949 if (nmk->clk_freq <= I2C_MAX_STANDARD_MODE_FREQ)
950 nmk->sm = I2C_FREQ_MODE_STANDARD;
951 else
952 nmk->sm = I2C_FREQ_MODE_FAST;
953 nmk->tft = 1; /* Tx FIFO threshold */
954 nmk->rft = 8; /* Rx FIFO threshold */
955 nmk->timeout = 200; /* Slave response timeout(ms) */
956 }
957
nmk_i2c_probe(struct amba_device * adev,const struct amba_id * id)958 static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
959 {
960 int ret = 0;
961 struct device_node *np = adev->dev.of_node;
962 struct nmk_i2c_dev *dev;
963 struct i2c_adapter *adap;
964 struct i2c_vendor_data *vendor = id->data;
965 u32 max_fifo_threshold = (vendor->fifodepth / 2) - 1;
966
967 dev = devm_kzalloc(&adev->dev, sizeof(*dev), GFP_KERNEL);
968 if (!dev)
969 return -ENOMEM;
970
971 dev->vendor = vendor;
972 dev->adev = adev;
973 nmk_i2c_of_probe(np, dev);
974
975 if (dev->tft > max_fifo_threshold) {
976 dev_warn(&adev->dev, "requested TX FIFO threshold %u, adjusted down to %u\n",
977 dev->tft, max_fifo_threshold);
978 dev->tft = max_fifo_threshold;
979 }
980
981 if (dev->rft > max_fifo_threshold) {
982 dev_warn(&adev->dev, "requested RX FIFO threshold %u, adjusted down to %u\n",
983 dev->rft, max_fifo_threshold);
984 dev->rft = max_fifo_threshold;
985 }
986
987 amba_set_drvdata(adev, dev);
988
989 dev->virtbase = devm_ioremap(&adev->dev, adev->res.start,
990 resource_size(&adev->res));
991 if (!dev->virtbase)
992 return -ENOMEM;
993
994 dev->irq = adev->irq[0];
995 ret = devm_request_irq(&adev->dev, dev->irq, i2c_irq_handler, 0,
996 DRIVER_NAME, dev);
997 if (ret)
998 return dev_err_probe(&adev->dev, ret,
999 "cannot claim the irq %d\n", dev->irq);
1000
1001 dev->clk = devm_clk_get_enabled(&adev->dev, NULL);
1002 if (IS_ERR(dev->clk))
1003 return dev_err_probe(&adev->dev, PTR_ERR(dev->clk),
1004 "could enable i2c clock\n");
1005
1006 init_hw(dev);
1007
1008 adap = &dev->adap;
1009 adap->dev.of_node = np;
1010 adap->dev.parent = &adev->dev;
1011 adap->owner = THIS_MODULE;
1012 adap->class = I2C_CLASS_DEPRECATED;
1013 adap->algo = &nmk_i2c_algo;
1014 adap->timeout = msecs_to_jiffies(dev->timeout);
1015 snprintf(adap->name, sizeof(adap->name),
1016 "Nomadik I2C at %pR", &adev->res);
1017
1018 i2c_set_adapdata(adap, dev);
1019
1020 dev_info(&adev->dev,
1021 "initialize %s on virtual base %p\n",
1022 adap->name, dev->virtbase);
1023
1024 ret = i2c_add_adapter(adap);
1025 if (ret)
1026 return ret;
1027
1028 pm_runtime_put(&adev->dev);
1029
1030 return 0;
1031 }
1032
nmk_i2c_remove(struct amba_device * adev)1033 static void nmk_i2c_remove(struct amba_device *adev)
1034 {
1035 struct nmk_i2c_dev *dev = amba_get_drvdata(adev);
1036
1037 i2c_del_adapter(&dev->adap);
1038 flush_i2c_fifo(dev);
1039 disable_all_interrupts(dev);
1040 clear_all_interrupts(dev);
1041 /* disable the controller */
1042 i2c_clr_bit(dev->virtbase + I2C_CR, I2C_CR_PE);
1043 }
1044
1045 static struct i2c_vendor_data vendor_stn8815 = {
1046 .has_mtdws = false,
1047 .fifodepth = 16, /* Guessed from TFTR/RFTR = 7 */
1048 };
1049
1050 static struct i2c_vendor_data vendor_db8500 = {
1051 .has_mtdws = true,
1052 .fifodepth = 32, /* Guessed from TFTR/RFTR = 15 */
1053 };
1054
1055 static const struct amba_id nmk_i2c_ids[] = {
1056 {
1057 .id = 0x00180024,
1058 .mask = 0x00ffffff,
1059 .data = &vendor_stn8815,
1060 },
1061 {
1062 .id = 0x00380024,
1063 .mask = 0x00ffffff,
1064 .data = &vendor_db8500,
1065 },
1066 {},
1067 };
1068
1069 MODULE_DEVICE_TABLE(amba, nmk_i2c_ids);
1070
1071 static struct amba_driver nmk_i2c_driver = {
1072 .drv = {
1073 .owner = THIS_MODULE,
1074 .name = DRIVER_NAME,
1075 .pm = pm_ptr(&nmk_i2c_pm),
1076 },
1077 .id_table = nmk_i2c_ids,
1078 .probe = nmk_i2c_probe,
1079 .remove = nmk_i2c_remove,
1080 };
1081
nmk_i2c_init(void)1082 static int __init nmk_i2c_init(void)
1083 {
1084 return amba_driver_register(&nmk_i2c_driver);
1085 }
1086
nmk_i2c_exit(void)1087 static void __exit nmk_i2c_exit(void)
1088 {
1089 amba_driver_unregister(&nmk_i2c_driver);
1090 }
1091
1092 subsys_initcall(nmk_i2c_init);
1093 module_exit(nmk_i2c_exit);
1094
1095 MODULE_AUTHOR("Sachin Verma");
1096 MODULE_AUTHOR("Srinidhi KASAGAR");
1097 MODULE_DESCRIPTION("Nomadik/Ux500 I2C driver");
1098 MODULE_LICENSE("GPL");
1099
