1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * i2c-xiic.c
4 * Copyright (c) 2002-2007 Xilinx Inc.
5 * Copyright (c) 2009-2010 Intel Corporation
6 *
7 * This code was implemented by Mocean Laboratories AB when porting linux
8 * to the automotive development board Russellville. The copyright holder
9 * as seen in the header is Intel corporation.
10 * Mocean Laboratories forked off the GNU/Linux platform work into a
11 * separate company called Pelagicore AB, which committed the code to the
12 * kernel.
13 */
14
15 /* Supports:
16 * Xilinx IIC
17 */
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/errno.h>
21 #include <linux/err.h>
22 #include <linux/delay.h>
23 #include <linux/platform_device.h>
24 #include <linux/i2c.h>
25 #include <linux/interrupt.h>
26 #include <linux/wait.h>
27 #include <linux/platform_data/i2c-xiic.h>
28 #include <linux/io.h>
29 #include <linux/slab.h>
30 #include <linux/of.h>
31 #include <linux/clk.h>
32 #include <linux/pm_runtime.h>
33
34 #define DRIVER_NAME "xiic-i2c"
35
36 enum xilinx_i2c_state {
37 STATE_DONE,
38 STATE_ERROR,
39 STATE_START
40 };
41
42 enum xiic_endian {
43 LITTLE,
44 BIG
45 };
46
47 /**
48 * struct xiic_i2c - Internal representation of the XIIC I2C bus
49 * @dev: Pointer to device structure
50 * @base: Memory base of the HW registers
51 * @wait: Wait queue for callers
52 * @adap: Kernel adapter representation
53 * @tx_msg: Messages from above to be sent
54 * @lock: Mutual exclusion
55 * @tx_pos: Current pos in TX message
56 * @nmsgs: Number of messages in tx_msg
57 * @rx_msg: Current RX message
58 * @rx_pos: Position within current RX message
59 * @endianness: big/little-endian byte order
60 * @clk: Pointer to AXI4-lite input clock
61 * @state: See STATE_
62 * @singlemaster: Indicates bus is single master
63 */
64 struct xiic_i2c {
65 struct device *dev;
66 void __iomem *base;
67 wait_queue_head_t wait;
68 struct i2c_adapter adap;
69 struct i2c_msg *tx_msg;
70 struct mutex lock;
71 unsigned int tx_pos;
72 unsigned int nmsgs;
73 struct i2c_msg *rx_msg;
74 int rx_pos;
75 enum xiic_endian endianness;
76 struct clk *clk;
77 enum xilinx_i2c_state state;
78 bool singlemaster;
79 };
80
81
82 #define XIIC_MSB_OFFSET 0
83 #define XIIC_REG_OFFSET (0x100+XIIC_MSB_OFFSET)
84
85 /*
86 * Register offsets in bytes from RegisterBase. Three is added to the
87 * base offset to access LSB (IBM style) of the word
88 */
89 #define XIIC_CR_REG_OFFSET (0x00+XIIC_REG_OFFSET) /* Control Register */
90 #define XIIC_SR_REG_OFFSET (0x04+XIIC_REG_OFFSET) /* Status Register */
91 #define XIIC_DTR_REG_OFFSET (0x08+XIIC_REG_OFFSET) /* Data Tx Register */
92 #define XIIC_DRR_REG_OFFSET (0x0C+XIIC_REG_OFFSET) /* Data Rx Register */
93 #define XIIC_ADR_REG_OFFSET (0x10+XIIC_REG_OFFSET) /* Address Register */
94 #define XIIC_TFO_REG_OFFSET (0x14+XIIC_REG_OFFSET) /* Tx FIFO Occupancy */
95 #define XIIC_RFO_REG_OFFSET (0x18+XIIC_REG_OFFSET) /* Rx FIFO Occupancy */
96 #define XIIC_TBA_REG_OFFSET (0x1C+XIIC_REG_OFFSET) /* 10 Bit Address reg */
97 #define XIIC_RFD_REG_OFFSET (0x20+XIIC_REG_OFFSET) /* Rx FIFO Depth reg */
98 #define XIIC_GPO_REG_OFFSET (0x24+XIIC_REG_OFFSET) /* Output Register */
99
100 /* Control Register masks */
101 #define XIIC_CR_ENABLE_DEVICE_MASK 0x01 /* Device enable = 1 */
102 #define XIIC_CR_TX_FIFO_RESET_MASK 0x02 /* Transmit FIFO reset=1 */
103 #define XIIC_CR_MSMS_MASK 0x04 /* Master starts Txing=1 */
104 #define XIIC_CR_DIR_IS_TX_MASK 0x08 /* Dir of tx. Txing=1 */
105 #define XIIC_CR_NO_ACK_MASK 0x10 /* Tx Ack. NO ack = 1 */
106 #define XIIC_CR_REPEATED_START_MASK 0x20 /* Repeated start = 1 */
107 #define XIIC_CR_GENERAL_CALL_MASK 0x40 /* Gen Call enabled = 1 */
108
109 /* Status Register masks */
110 #define XIIC_SR_GEN_CALL_MASK 0x01 /* 1=a mstr issued a GC */
111 #define XIIC_SR_ADDR_AS_SLAVE_MASK 0x02 /* 1=when addr as slave */
112 #define XIIC_SR_BUS_BUSY_MASK 0x04 /* 1 = bus is busy */
113 #define XIIC_SR_MSTR_RDING_SLAVE_MASK 0x08 /* 1=Dir: mstr <-- slave */
114 #define XIIC_SR_TX_FIFO_FULL_MASK 0x10 /* 1 = Tx FIFO full */
115 #define XIIC_SR_RX_FIFO_FULL_MASK 0x20 /* 1 = Rx FIFO full */
116 #define XIIC_SR_RX_FIFO_EMPTY_MASK 0x40 /* 1 = Rx FIFO empty */
117 #define XIIC_SR_TX_FIFO_EMPTY_MASK 0x80 /* 1 = Tx FIFO empty */
118
119 /* Interrupt Status Register masks Interrupt occurs when... */
120 #define XIIC_INTR_ARB_LOST_MASK 0x01 /* 1 = arbitration lost */
121 #define XIIC_INTR_TX_ERROR_MASK 0x02 /* 1=Tx error/msg complete */
122 #define XIIC_INTR_TX_EMPTY_MASK 0x04 /* 1 = Tx FIFO/reg empty */
123 #define XIIC_INTR_RX_FULL_MASK 0x08 /* 1=Rx FIFO/reg=OCY level */
124 #define XIIC_INTR_BNB_MASK 0x10 /* 1 = Bus not busy */
125 #define XIIC_INTR_AAS_MASK 0x20 /* 1 = when addr as slave */
126 #define XIIC_INTR_NAAS_MASK 0x40 /* 1 = not addr as slave */
127 #define XIIC_INTR_TX_HALF_MASK 0x80 /* 1 = TX FIFO half empty */
128
129 /* The following constants specify the depth of the FIFOs */
130 #define IIC_RX_FIFO_DEPTH 16 /* Rx fifo capacity */
131 #define IIC_TX_FIFO_DEPTH 16 /* Tx fifo capacity */
132
133 /* The following constants specify groups of interrupts that are typically
134 * enabled or disables at the same time
135 */
136 #define XIIC_TX_INTERRUPTS \
137 (XIIC_INTR_TX_ERROR_MASK | XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)
138
139 #define XIIC_TX_RX_INTERRUPTS (XIIC_INTR_RX_FULL_MASK | XIIC_TX_INTERRUPTS)
140
141 /*
142 * Tx Fifo upper bit masks.
143 */
144 #define XIIC_TX_DYN_START_MASK 0x0100 /* 1 = Set dynamic start */
145 #define XIIC_TX_DYN_STOP_MASK 0x0200 /* 1 = Set dynamic stop */
146
147 /*
148 * The following constants define the register offsets for the Interrupt
149 * registers. There are some holes in the memory map for reserved addresses
150 * to allow other registers to be added and still match the memory map of the
151 * interrupt controller registers
152 */
153 #define XIIC_DGIER_OFFSET 0x1C /* Device Global Interrupt Enable Register */
154 #define XIIC_IISR_OFFSET 0x20 /* Interrupt Status Register */
155 #define XIIC_IIER_OFFSET 0x28 /* Interrupt Enable Register */
156 #define XIIC_RESETR_OFFSET 0x40 /* Reset Register */
157
158 #define XIIC_RESET_MASK 0xAUL
159
160 #define XIIC_PM_TIMEOUT 1000 /* ms */
161 /* timeout waiting for the controller to respond */
162 #define XIIC_I2C_TIMEOUT (msecs_to_jiffies(1000))
163 /*
164 * The following constant is used for the device global interrupt enable
165 * register, to enable all interrupts for the device, this is the only bit
166 * in the register
167 */
168 #define XIIC_GINTR_ENABLE_MASK 0x80000000UL
169
170 #define xiic_tx_space(i2c) ((i2c)->tx_msg->len - (i2c)->tx_pos)
171 #define xiic_rx_space(i2c) ((i2c)->rx_msg->len - (i2c)->rx_pos)
172
173 static int xiic_start_xfer(struct xiic_i2c *i2c);
174 static void __xiic_start_xfer(struct xiic_i2c *i2c);
175
176 /*
177 * For the register read and write functions, a little-endian and big-endian
178 * version are necessary. Endianness is detected during the probe function.
179 * Only the least significant byte [doublet] of the register are ever
180 * accessed. This requires an offset of 3 [2] from the base address for
181 * big-endian systems.
182 */
183
xiic_setreg8(struct xiic_i2c * i2c,int reg,u8 value)184 static inline void xiic_setreg8(struct xiic_i2c *i2c, int reg, u8 value)
185 {
186 if (i2c->endianness == LITTLE)
187 iowrite8(value, i2c->base + reg);
188 else
189 iowrite8(value, i2c->base + reg + 3);
190 }
191
xiic_getreg8(struct xiic_i2c * i2c,int reg)192 static inline u8 xiic_getreg8(struct xiic_i2c *i2c, int reg)
193 {
194 u8 ret;
195
196 if (i2c->endianness == LITTLE)
197 ret = ioread8(i2c->base + reg);
198 else
199 ret = ioread8(i2c->base + reg + 3);
200 return ret;
201 }
202
xiic_setreg16(struct xiic_i2c * i2c,int reg,u16 value)203 static inline void xiic_setreg16(struct xiic_i2c *i2c, int reg, u16 value)
204 {
205 if (i2c->endianness == LITTLE)
206 iowrite16(value, i2c->base + reg);
207 else
208 iowrite16be(value, i2c->base + reg + 2);
209 }
210
xiic_setreg32(struct xiic_i2c * i2c,int reg,int value)211 static inline void xiic_setreg32(struct xiic_i2c *i2c, int reg, int value)
212 {
213 if (i2c->endianness == LITTLE)
214 iowrite32(value, i2c->base + reg);
215 else
216 iowrite32be(value, i2c->base + reg);
217 }
218
xiic_getreg32(struct xiic_i2c * i2c,int reg)219 static inline int xiic_getreg32(struct xiic_i2c *i2c, int reg)
220 {
221 u32 ret;
222
223 if (i2c->endianness == LITTLE)
224 ret = ioread32(i2c->base + reg);
225 else
226 ret = ioread32be(i2c->base + reg);
227 return ret;
228 }
229
xiic_irq_dis(struct xiic_i2c * i2c,u32 mask)230 static inline void xiic_irq_dis(struct xiic_i2c *i2c, u32 mask)
231 {
232 u32 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
233 xiic_setreg32(i2c, XIIC_IIER_OFFSET, ier & ~mask);
234 }
235
xiic_irq_en(struct xiic_i2c * i2c,u32 mask)236 static inline void xiic_irq_en(struct xiic_i2c *i2c, u32 mask)
237 {
238 u32 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
239 xiic_setreg32(i2c, XIIC_IIER_OFFSET, ier | mask);
240 }
241
xiic_irq_clr(struct xiic_i2c * i2c,u32 mask)242 static inline void xiic_irq_clr(struct xiic_i2c *i2c, u32 mask)
243 {
244 u32 isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
245 xiic_setreg32(i2c, XIIC_IISR_OFFSET, isr & mask);
246 }
247
xiic_irq_clr_en(struct xiic_i2c * i2c,u32 mask)248 static inline void xiic_irq_clr_en(struct xiic_i2c *i2c, u32 mask)
249 {
250 xiic_irq_clr(i2c, mask);
251 xiic_irq_en(i2c, mask);
252 }
253
xiic_clear_rx_fifo(struct xiic_i2c * i2c)254 static int xiic_clear_rx_fifo(struct xiic_i2c *i2c)
255 {
256 u8 sr;
257 unsigned long timeout;
258
259 timeout = jiffies + XIIC_I2C_TIMEOUT;
260 for (sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET);
261 !(sr & XIIC_SR_RX_FIFO_EMPTY_MASK);
262 sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET)) {
263 xiic_getreg8(i2c, XIIC_DRR_REG_OFFSET);
264 if (time_after(jiffies, timeout)) {
265 dev_err(i2c->dev, "Failed to clear rx fifo\n");
266 return -ETIMEDOUT;
267 }
268 }
269
270 return 0;
271 }
272
xiic_reinit(struct xiic_i2c * i2c)273 static int xiic_reinit(struct xiic_i2c *i2c)
274 {
275 int ret;
276
277 xiic_setreg32(i2c, XIIC_RESETR_OFFSET, XIIC_RESET_MASK);
278
279 /* Set receive Fifo depth to maximum (zero based). */
280 xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, IIC_RX_FIFO_DEPTH - 1);
281
282 /* Reset Tx Fifo. */
283 xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_TX_FIFO_RESET_MASK);
284
285 /* Enable IIC Device, remove Tx Fifo reset & disable general call. */
286 xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_ENABLE_DEVICE_MASK);
287
288 /* make sure RX fifo is empty */
289 ret = xiic_clear_rx_fifo(i2c);
290 if (ret)
291 return ret;
292
293 /* Enable interrupts */
294 xiic_setreg32(i2c, XIIC_DGIER_OFFSET, XIIC_GINTR_ENABLE_MASK);
295
296 xiic_irq_clr_en(i2c, XIIC_INTR_ARB_LOST_MASK);
297
298 return 0;
299 }
300
xiic_deinit(struct xiic_i2c * i2c)301 static void xiic_deinit(struct xiic_i2c *i2c)
302 {
303 u8 cr;
304
305 xiic_setreg32(i2c, XIIC_RESETR_OFFSET, XIIC_RESET_MASK);
306
307 /* Disable IIC Device. */
308 cr = xiic_getreg8(i2c, XIIC_CR_REG_OFFSET);
309 xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, cr & ~XIIC_CR_ENABLE_DEVICE_MASK);
310 }
311
xiic_read_rx(struct xiic_i2c * i2c)312 static void xiic_read_rx(struct xiic_i2c *i2c)
313 {
314 u8 bytes_in_fifo;
315 int i;
316
317 bytes_in_fifo = xiic_getreg8(i2c, XIIC_RFO_REG_OFFSET) + 1;
318
319 dev_dbg(i2c->adap.dev.parent,
320 "%s entry, bytes in fifo: %d, msg: %d, SR: 0x%x, CR: 0x%x\n",
321 __func__, bytes_in_fifo, xiic_rx_space(i2c),
322 xiic_getreg8(i2c, XIIC_SR_REG_OFFSET),
323 xiic_getreg8(i2c, XIIC_CR_REG_OFFSET));
324
325 if (bytes_in_fifo > xiic_rx_space(i2c))
326 bytes_in_fifo = xiic_rx_space(i2c);
327
328 for (i = 0; i < bytes_in_fifo; i++)
329 i2c->rx_msg->buf[i2c->rx_pos++] =
330 xiic_getreg8(i2c, XIIC_DRR_REG_OFFSET);
331
332 xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET,
333 (xiic_rx_space(i2c) > IIC_RX_FIFO_DEPTH) ?
334 IIC_RX_FIFO_DEPTH - 1 : xiic_rx_space(i2c) - 1);
335 }
336
xiic_tx_fifo_space(struct xiic_i2c * i2c)337 static int xiic_tx_fifo_space(struct xiic_i2c *i2c)
338 {
339 /* return the actual space left in the FIFO */
340 return IIC_TX_FIFO_DEPTH - xiic_getreg8(i2c, XIIC_TFO_REG_OFFSET) - 1;
341 }
342
xiic_fill_tx_fifo(struct xiic_i2c * i2c)343 static void xiic_fill_tx_fifo(struct xiic_i2c *i2c)
344 {
345 u8 fifo_space = xiic_tx_fifo_space(i2c);
346 int len = xiic_tx_space(i2c);
347
348 len = (len > fifo_space) ? fifo_space : len;
349
350 dev_dbg(i2c->adap.dev.parent, "%s entry, len: %d, fifo space: %d\n",
351 __func__, len, fifo_space);
352
353 while (len--) {
354 u16 data = i2c->tx_msg->buf[i2c->tx_pos++];
355 if ((xiic_tx_space(i2c) == 0) && (i2c->nmsgs == 1)) {
356 /* last message in transfer -> STOP */
357 data |= XIIC_TX_DYN_STOP_MASK;
358 dev_dbg(i2c->adap.dev.parent, "%s TX STOP\n", __func__);
359 }
360 xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
361 }
362 }
363
xiic_wakeup(struct xiic_i2c * i2c,int code)364 static void xiic_wakeup(struct xiic_i2c *i2c, int code)
365 {
366 i2c->tx_msg = NULL;
367 i2c->rx_msg = NULL;
368 i2c->nmsgs = 0;
369 i2c->state = code;
370 wake_up(&i2c->wait);
371 }
372
xiic_process(int irq,void * dev_id)373 static irqreturn_t xiic_process(int irq, void *dev_id)
374 {
375 struct xiic_i2c *i2c = dev_id;
376 u32 pend, isr, ier;
377 u32 clr = 0;
378 int xfer_more = 0;
379 int wakeup_req = 0;
380 int wakeup_code = 0;
381
382 /* Get the interrupt Status from the IPIF. There is no clearing of
383 * interrupts in the IPIF. Interrupts must be cleared at the source.
384 * To find which interrupts are pending; AND interrupts pending with
385 * interrupts masked.
386 */
387 mutex_lock(&i2c->lock);
388 isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
389 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
390 pend = isr & ier;
391
392 dev_dbg(i2c->adap.dev.parent, "%s: IER: 0x%x, ISR: 0x%x, pend: 0x%x\n",
393 __func__, ier, isr, pend);
394 dev_dbg(i2c->adap.dev.parent, "%s: SR: 0x%x, msg: %p, nmsgs: %d\n",
395 __func__, xiic_getreg8(i2c, XIIC_SR_REG_OFFSET),
396 i2c->tx_msg, i2c->nmsgs);
397
398
399 /* Service requesting interrupt */
400 if ((pend & XIIC_INTR_ARB_LOST_MASK) ||
401 ((pend & XIIC_INTR_TX_ERROR_MASK) &&
402 !(pend & XIIC_INTR_RX_FULL_MASK))) {
403 /* bus arbritration lost, or...
404 * Transmit error _OR_ RX completed
405 * if this happens when RX_FULL is not set
406 * this is probably a TX error
407 */
408
409 dev_dbg(i2c->adap.dev.parent, "%s error\n", __func__);
410
411 /* dynamic mode seem to suffer from problems if we just flushes
412 * fifos and the next message is a TX with len 0 (only addr)
413 * reset the IP instead of just flush fifos
414 */
415 xiic_reinit(i2c);
416
417 if (i2c->rx_msg) {
418 wakeup_req = 1;
419 wakeup_code = STATE_ERROR;
420 }
421 if (i2c->tx_msg) {
422 wakeup_req = 1;
423 wakeup_code = STATE_ERROR;
424 }
425 /* don't try to handle other events */
426 goto out;
427 }
428 if (pend & XIIC_INTR_RX_FULL_MASK) {
429 /* Receive register/FIFO is full */
430
431 clr |= XIIC_INTR_RX_FULL_MASK;
432 if (!i2c->rx_msg) {
433 dev_dbg(i2c->adap.dev.parent,
434 "%s unexpected RX IRQ\n", __func__);
435 xiic_clear_rx_fifo(i2c);
436 goto out;
437 }
438
439 xiic_read_rx(i2c);
440 if (xiic_rx_space(i2c) == 0) {
441 /* this is the last part of the message */
442 i2c->rx_msg = NULL;
443
444 /* also clear TX error if there (RX complete) */
445 clr |= (isr & XIIC_INTR_TX_ERROR_MASK);
446
447 dev_dbg(i2c->adap.dev.parent,
448 "%s end of message, nmsgs: %d\n",
449 __func__, i2c->nmsgs);
450
451 /* send next message if this wasn't the last,
452 * otherwise the transfer will be finialise when
453 * receiving the bus not busy interrupt
454 */
455 if (i2c->nmsgs > 1) {
456 i2c->nmsgs--;
457 i2c->tx_msg++;
458 dev_dbg(i2c->adap.dev.parent,
459 "%s will start next...\n", __func__);
460 xfer_more = 1;
461 }
462 }
463 }
464 if (pend & XIIC_INTR_BNB_MASK) {
465 /* IIC bus has transitioned to not busy */
466 clr |= XIIC_INTR_BNB_MASK;
467
468 /* The bus is not busy, disable BusNotBusy interrupt */
469 xiic_irq_dis(i2c, XIIC_INTR_BNB_MASK);
470
471 if (!i2c->tx_msg)
472 goto out;
473
474 wakeup_req = 1;
475
476 if (i2c->nmsgs == 1 && !i2c->rx_msg &&
477 xiic_tx_space(i2c) == 0)
478 wakeup_code = STATE_DONE;
479 else
480 wakeup_code = STATE_ERROR;
481 }
482 if (pend & (XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)) {
483 /* Transmit register/FIFO is empty or ½ empty */
484
485 clr |= (pend &
486 (XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK));
487
488 if (!i2c->tx_msg) {
489 dev_dbg(i2c->adap.dev.parent,
490 "%s unexpected TX IRQ\n", __func__);
491 goto out;
492 }
493
494 xiic_fill_tx_fifo(i2c);
495
496 /* current message sent and there is space in the fifo */
497 if (!xiic_tx_space(i2c) && xiic_tx_fifo_space(i2c) >= 2) {
498 dev_dbg(i2c->adap.dev.parent,
499 "%s end of message sent, nmsgs: %d\n",
500 __func__, i2c->nmsgs);
501 if (i2c->nmsgs > 1) {
502 i2c->nmsgs--;
503 i2c->tx_msg++;
504 xfer_more = 1;
505 } else {
506 xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
507
508 dev_dbg(i2c->adap.dev.parent,
509 "%s Got TX IRQ but no more to do...\n",
510 __func__);
511 }
512 } else if (!xiic_tx_space(i2c) && (i2c->nmsgs == 1))
513 /* current frame is sent and is last,
514 * make sure to disable tx half
515 */
516 xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
517 }
518 out:
519 dev_dbg(i2c->adap.dev.parent, "%s clr: 0x%x\n", __func__, clr);
520
521 xiic_setreg32(i2c, XIIC_IISR_OFFSET, clr);
522 if (xfer_more)
523 __xiic_start_xfer(i2c);
524 if (wakeup_req)
525 xiic_wakeup(i2c, wakeup_code);
526
527 WARN_ON(xfer_more && wakeup_req);
528
529 mutex_unlock(&i2c->lock);
530 return IRQ_HANDLED;
531 }
532
xiic_bus_busy(struct xiic_i2c * i2c)533 static int xiic_bus_busy(struct xiic_i2c *i2c)
534 {
535 u8 sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET);
536
537 return (sr & XIIC_SR_BUS_BUSY_MASK) ? -EBUSY : 0;
538 }
539
xiic_busy(struct xiic_i2c * i2c)540 static int xiic_busy(struct xiic_i2c *i2c)
541 {
542 int tries = 3;
543 int err;
544
545 if (i2c->tx_msg)
546 return -EBUSY;
547
548 /* In single master mode bus can only be busy, when in use by this
549 * driver. If the register indicates bus being busy for some reason we
550 * should ignore it, since bus will never be released and i2c will be
551 * stuck forever.
552 */
553 if (i2c->singlemaster) {
554 return 0;
555 }
556
557 /* for instance if previous transfer was terminated due to TX error
558 * it might be that the bus is on it's way to become available
559 * give it at most 3 ms to wake
560 */
561 err = xiic_bus_busy(i2c);
562 while (err && tries--) {
563 msleep(1);
564 err = xiic_bus_busy(i2c);
565 }
566
567 return err;
568 }
569
xiic_start_recv(struct xiic_i2c * i2c)570 static void xiic_start_recv(struct xiic_i2c *i2c)
571 {
572 u8 rx_watermark;
573 struct i2c_msg *msg = i2c->rx_msg = i2c->tx_msg;
574 unsigned long flags;
575
576 /* Clear and enable Rx full interrupt. */
577 xiic_irq_clr_en(i2c, XIIC_INTR_RX_FULL_MASK | XIIC_INTR_TX_ERROR_MASK);
578
579 /* we want to get all but last byte, because the TX_ERROR IRQ is used
580 * to inidicate error ACK on the address, and negative ack on the last
581 * received byte, so to not mix them receive all but last.
582 * In the case where there is only one byte to receive
583 * we can check if ERROR and RX full is set at the same time
584 */
585 rx_watermark = msg->len;
586 if (rx_watermark > IIC_RX_FIFO_DEPTH)
587 rx_watermark = IIC_RX_FIFO_DEPTH;
588 xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, rx_watermark - 1);
589
590 local_irq_save(flags);
591 if (!(msg->flags & I2C_M_NOSTART))
592 /* write the address */
593 xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET,
594 i2c_8bit_addr_from_msg(msg) | XIIC_TX_DYN_START_MASK);
595
596 xiic_irq_clr_en(i2c, XIIC_INTR_BNB_MASK);
597
598 xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET,
599 msg->len | ((i2c->nmsgs == 1) ? XIIC_TX_DYN_STOP_MASK : 0));
600 local_irq_restore(flags);
601
602 if (i2c->nmsgs == 1)
603 /* very last, enable bus not busy as well */
604 xiic_irq_clr_en(i2c, XIIC_INTR_BNB_MASK);
605
606 /* the message is tx:ed */
607 i2c->tx_pos = msg->len;
608 }
609
xiic_start_send(struct xiic_i2c * i2c)610 static void xiic_start_send(struct xiic_i2c *i2c)
611 {
612 struct i2c_msg *msg = i2c->tx_msg;
613
614 xiic_irq_clr(i2c, XIIC_INTR_TX_ERROR_MASK);
615
616 dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, len: %d",
617 __func__, msg, msg->len);
618 dev_dbg(i2c->adap.dev.parent, "%s entry, ISR: 0x%x, CR: 0x%x\n",
619 __func__, xiic_getreg32(i2c, XIIC_IISR_OFFSET),
620 xiic_getreg8(i2c, XIIC_CR_REG_OFFSET));
621
622 if (!(msg->flags & I2C_M_NOSTART)) {
623 /* write the address */
624 u16 data = i2c_8bit_addr_from_msg(msg) |
625 XIIC_TX_DYN_START_MASK;
626 if ((i2c->nmsgs == 1) && msg->len == 0)
627 /* no data and last message -> add STOP */
628 data |= XIIC_TX_DYN_STOP_MASK;
629
630 xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
631 }
632
633 xiic_fill_tx_fifo(i2c);
634
635 /* Clear any pending Tx empty, Tx Error and then enable them. */
636 xiic_irq_clr_en(i2c, XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_ERROR_MASK |
637 XIIC_INTR_BNB_MASK);
638 }
639
xiic_isr(int irq,void * dev_id)640 static irqreturn_t xiic_isr(int irq, void *dev_id)
641 {
642 struct xiic_i2c *i2c = dev_id;
643 u32 pend, isr, ier;
644 irqreturn_t ret = IRQ_NONE;
645 /* Do not processes a devices interrupts if the device has no
646 * interrupts pending
647 */
648
649 dev_dbg(i2c->adap.dev.parent, "%s entry\n", __func__);
650
651 isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
652 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
653 pend = isr & ier;
654 if (pend)
655 ret = IRQ_WAKE_THREAD;
656
657 return ret;
658 }
659
__xiic_start_xfer(struct xiic_i2c * i2c)660 static void __xiic_start_xfer(struct xiic_i2c *i2c)
661 {
662 int first = 1;
663 int fifo_space = xiic_tx_fifo_space(i2c);
664 dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, fifos space: %d\n",
665 __func__, i2c->tx_msg, fifo_space);
666
667 if (!i2c->tx_msg)
668 return;
669
670 i2c->rx_pos = 0;
671 i2c->tx_pos = 0;
672 i2c->state = STATE_START;
673 while ((fifo_space >= 2) && (first || (i2c->nmsgs > 1))) {
674 if (!first) {
675 i2c->nmsgs--;
676 i2c->tx_msg++;
677 i2c->tx_pos = 0;
678 } else
679 first = 0;
680
681 if (i2c->tx_msg->flags & I2C_M_RD) {
682 /* we dont date putting several reads in the FIFO */
683 xiic_start_recv(i2c);
684 return;
685 } else {
686 xiic_start_send(i2c);
687 if (xiic_tx_space(i2c) != 0) {
688 /* the message could not be completely sent */
689 break;
690 }
691 }
692
693 fifo_space = xiic_tx_fifo_space(i2c);
694 }
695
696 /* there are more messages or the current one could not be completely
697 * put into the FIFO, also enable the half empty interrupt
698 */
699 if (i2c->nmsgs > 1 || xiic_tx_space(i2c))
700 xiic_irq_clr_en(i2c, XIIC_INTR_TX_HALF_MASK);
701
702 }
703
xiic_start_xfer(struct xiic_i2c * i2c)704 static int xiic_start_xfer(struct xiic_i2c *i2c)
705 {
706 int ret;
707 mutex_lock(&i2c->lock);
708
709 ret = xiic_reinit(i2c);
710 if (!ret)
711 __xiic_start_xfer(i2c);
712
713 mutex_unlock(&i2c->lock);
714
715 return ret;
716 }
717
xiic_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)718 static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
719 {
720 struct xiic_i2c *i2c = i2c_get_adapdata(adap);
721 int err;
722
723 dev_dbg(adap->dev.parent, "%s entry SR: 0x%x\n", __func__,
724 xiic_getreg8(i2c, XIIC_SR_REG_OFFSET));
725
726 err = pm_runtime_resume_and_get(i2c->dev);
727 if (err < 0)
728 return err;
729
730 err = xiic_busy(i2c);
731 if (err)
732 goto out;
733
734 i2c->tx_msg = msgs;
735 i2c->nmsgs = num;
736
737 err = xiic_start_xfer(i2c);
738 if (err < 0) {
739 dev_err(adap->dev.parent, "Error xiic_start_xfer\n");
740 goto out;
741 }
742
743 if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
744 (i2c->state == STATE_DONE), HZ)) {
745 err = (i2c->state == STATE_DONE) ? num : -EIO;
746 goto out;
747 } else {
748 i2c->tx_msg = NULL;
749 i2c->rx_msg = NULL;
750 i2c->nmsgs = 0;
751 err = -ETIMEDOUT;
752 goto out;
753 }
754 out:
755 pm_runtime_mark_last_busy(i2c->dev);
756 pm_runtime_put_autosuspend(i2c->dev);
757 return err;
758 }
759
xiic_func(struct i2c_adapter * adap)760 static u32 xiic_func(struct i2c_adapter *adap)
761 {
762 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
763 }
764
765 static const struct i2c_algorithm xiic_algorithm = {
766 .master_xfer = xiic_xfer,
767 .functionality = xiic_func,
768 };
769
770 static const struct i2c_adapter_quirks xiic_quirks = {
771 .max_read_len = 255,
772 };
773
774 static const struct i2c_adapter xiic_adapter = {
775 .owner = THIS_MODULE,
776 .class = I2C_CLASS_DEPRECATED,
777 .algo = &xiic_algorithm,
778 .quirks = &xiic_quirks,
779 };
780
781
xiic_i2c_probe(struct platform_device * pdev)782 static int xiic_i2c_probe(struct platform_device *pdev)
783 {
784 struct xiic_i2c *i2c;
785 struct xiic_i2c_platform_data *pdata;
786 struct resource *res;
787 int ret, irq;
788 u8 i;
789 u32 sr;
790
791 i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
792 if (!i2c)
793 return -ENOMEM;
794
795 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
796 i2c->base = devm_ioremap_resource(&pdev->dev, res);
797 if (IS_ERR(i2c->base))
798 return PTR_ERR(i2c->base);
799
800 irq = platform_get_irq(pdev, 0);
801 if (irq < 0)
802 return irq;
803
804 pdata = dev_get_platdata(&pdev->dev);
805
806 /* hook up driver to tree */
807 platform_set_drvdata(pdev, i2c);
808 i2c->adap = xiic_adapter;
809 i2c_set_adapdata(&i2c->adap, i2c);
810 i2c->adap.dev.parent = &pdev->dev;
811 i2c->adap.dev.of_node = pdev->dev.of_node;
812 snprintf(i2c->adap.name, sizeof(i2c->adap.name),
813 DRIVER_NAME " %s", pdev->name);
814
815 mutex_init(&i2c->lock);
816 init_waitqueue_head(&i2c->wait);
817
818 i2c->clk = devm_clk_get(&pdev->dev, NULL);
819 if (IS_ERR(i2c->clk))
820 return dev_err_probe(&pdev->dev, PTR_ERR(i2c->clk),
821 "input clock not found.\n");
822
823 ret = clk_prepare_enable(i2c->clk);
824 if (ret) {
825 dev_err(&pdev->dev, "Unable to enable clock.\n");
826 return ret;
827 }
828 i2c->dev = &pdev->dev;
829 pm_runtime_set_autosuspend_delay(i2c->dev, XIIC_PM_TIMEOUT);
830 pm_runtime_use_autosuspend(i2c->dev);
831 pm_runtime_set_active(i2c->dev);
832 pm_runtime_enable(i2c->dev);
833 ret = devm_request_threaded_irq(&pdev->dev, irq, xiic_isr,
834 xiic_process, IRQF_ONESHOT,
835 pdev->name, i2c);
836
837 if (ret < 0) {
838 dev_err(&pdev->dev, "Cannot claim IRQ\n");
839 goto err_clk_dis;
840 }
841
842 i2c->singlemaster =
843 of_property_read_bool(pdev->dev.of_node, "single-master");
844
845 /*
846 * Detect endianness
847 * Try to reset the TX FIFO. Then check the EMPTY flag. If it is not
848 * set, assume that the endianness was wrong and swap.
849 */
850 i2c->endianness = LITTLE;
851 xiic_setreg32(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_TX_FIFO_RESET_MASK);
852 /* Reset is cleared in xiic_reinit */
853 sr = xiic_getreg32(i2c, XIIC_SR_REG_OFFSET);
854 if (!(sr & XIIC_SR_TX_FIFO_EMPTY_MASK))
855 i2c->endianness = BIG;
856
857 ret = xiic_reinit(i2c);
858 if (ret < 0) {
859 dev_err(&pdev->dev, "Cannot xiic_reinit\n");
860 goto err_clk_dis;
861 }
862
863 /* add i2c adapter to i2c tree */
864 ret = i2c_add_adapter(&i2c->adap);
865 if (ret) {
866 xiic_deinit(i2c);
867 goto err_clk_dis;
868 }
869
870 if (pdata) {
871 /* add in known devices to the bus */
872 for (i = 0; i < pdata->num_devices; i++)
873 i2c_new_client_device(&i2c->adap, pdata->devices + i);
874 }
875
876 return 0;
877
878 err_clk_dis:
879 pm_runtime_set_suspended(&pdev->dev);
880 pm_runtime_disable(&pdev->dev);
881 clk_disable_unprepare(i2c->clk);
882 return ret;
883 }
884
xiic_i2c_remove(struct platform_device * pdev)885 static int xiic_i2c_remove(struct platform_device *pdev)
886 {
887 struct xiic_i2c *i2c = platform_get_drvdata(pdev);
888 int ret;
889
890 /* remove adapter & data */
891 i2c_del_adapter(&i2c->adap);
892
893 ret = pm_runtime_resume_and_get(i2c->dev);
894 if (ret < 0)
895 return ret;
896
897 xiic_deinit(i2c);
898 pm_runtime_put_sync(i2c->dev);
899 clk_disable_unprepare(i2c->clk);
900 pm_runtime_disable(&pdev->dev);
901 pm_runtime_set_suspended(&pdev->dev);
902 pm_runtime_dont_use_autosuspend(&pdev->dev);
903
904 return 0;
905 }
906
907 #if defined(CONFIG_OF)
908 static const struct of_device_id xiic_of_match[] = {
909 { .compatible = "xlnx,xps-iic-2.00.a", },
910 {},
911 };
912 MODULE_DEVICE_TABLE(of, xiic_of_match);
913 #endif
914
xiic_i2c_runtime_suspend(struct device * dev)915 static int __maybe_unused xiic_i2c_runtime_suspend(struct device *dev)
916 {
917 struct xiic_i2c *i2c = dev_get_drvdata(dev);
918
919 clk_disable(i2c->clk);
920
921 return 0;
922 }
923
xiic_i2c_runtime_resume(struct device * dev)924 static int __maybe_unused xiic_i2c_runtime_resume(struct device *dev)
925 {
926 struct xiic_i2c *i2c = dev_get_drvdata(dev);
927 int ret;
928
929 ret = clk_enable(i2c->clk);
930 if (ret) {
931 dev_err(dev, "Cannot enable clock.\n");
932 return ret;
933 }
934
935 return 0;
936 }
937
938 static const struct dev_pm_ops xiic_dev_pm_ops = {
939 SET_RUNTIME_PM_OPS(xiic_i2c_runtime_suspend,
940 xiic_i2c_runtime_resume, NULL)
941 };
942 static struct platform_driver xiic_i2c_driver = {
943 .probe = xiic_i2c_probe,
944 .remove = xiic_i2c_remove,
945 .driver = {
946 .name = DRIVER_NAME,
947 .of_match_table = of_match_ptr(xiic_of_match),
948 .pm = &xiic_dev_pm_ops,
949 },
950 };
951
952 module_platform_driver(xiic_i2c_driver);
953
954 MODULE_ALIAS("platform:" DRIVER_NAME);
955 MODULE_AUTHOR("info@mocean-labs.com");
956 MODULE_DESCRIPTION("Xilinx I2C bus driver");
957 MODULE_LICENSE("GPL v2");
958 MODULE_ALIAS("platform:"DRIVER_NAME);
959