1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * I2C bus driver for Amlogic Meson SoCs
4 *
5 * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
6 */
7
8 #include <linux/bitfield.h>
9 #include <linux/clk.h>
10 #include <linux/completion.h>
11 #include <linux/i2c.h>
12 #include <linux/interrupt.h>
13 #include <linux/io.h>
14 #include <linux/iopoll.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19 #include <linux/platform_device.h>
20 #include <linux/types.h>
21
22 /* Meson I2C register map */
23 #define REG_CTRL 0x00
24 #define REG_SLAVE_ADDR 0x04
25 #define REG_TOK_LIST0 0x08
26 #define REG_TOK_LIST1 0x0c
27 #define REG_TOK_WDATA0 0x10
28 #define REG_TOK_WDATA1 0x14
29 #define REG_TOK_RDATA0 0x18
30 #define REG_TOK_RDATA1 0x1c
31
32 /* Control register fields */
33 #define REG_CTRL_START BIT(0)
34 #define REG_CTRL_ACK_IGNORE BIT(1)
35 #define REG_CTRL_STATUS BIT(2)
36 #define REG_CTRL_ERROR BIT(3)
37 #define REG_CTRL_CLKDIV GENMASK(21, 12)
38 #define REG_CTRL_CLKDIVEXT GENMASK(29, 28)
39
40 #define REG_SLV_ADDR GENMASK(7, 0)
41 #define REG_SLV_SDA_FILTER GENMASK(10, 8)
42 #define REG_SLV_SCL_FILTER GENMASK(13, 11)
43 #define REG_SLV_SCL_LOW GENMASK(27, 16)
44 #define REG_SLV_SCL_LOW_EN BIT(28)
45
46 #define I2C_TIMEOUT_MS 500
47 #define FILTER_DELAY 15
48
49 enum {
50 TOKEN_END = 0,
51 TOKEN_START,
52 TOKEN_SLAVE_ADDR_WRITE,
53 TOKEN_SLAVE_ADDR_READ,
54 TOKEN_DATA,
55 TOKEN_DATA_LAST,
56 TOKEN_STOP,
57 };
58
59 enum {
60 STATE_IDLE,
61 STATE_READ,
62 STATE_WRITE,
63 };
64
65 struct meson_i2c_data {
66 unsigned char div_factor;
67 };
68
69 /**
70 * struct meson_i2c - Meson I2C device private data
71 *
72 * @adap: I2C adapter instance
73 * @dev: Pointer to device structure
74 * @regs: Base address of the device memory mapped registers
75 * @clk: Pointer to clock structure
76 * @msg: Pointer to the current I2C message
77 * @state: Current state in the driver state machine
78 * @last: Flag set for the last message in the transfer
79 * @count: Number of bytes to be sent/received in current transfer
80 * @pos: Current position in the send/receive buffer
81 * @error: Flag set when an error is received
82 * @lock: To avoid race conditions between irq handler and xfer code
83 * @done: Completion used to wait for transfer termination
84 * @tokens: Sequence of tokens to be written to the device
85 * @num_tokens: Number of tokens
86 * @data: Pointer to the controlller's platform data
87 */
88 struct meson_i2c {
89 struct i2c_adapter adap;
90 struct device *dev;
91 void __iomem *regs;
92 struct clk *clk;
93
94 struct i2c_msg *msg;
95 int state;
96 bool last;
97 int count;
98 int pos;
99 int error;
100
101 spinlock_t lock;
102 struct completion done;
103 u32 tokens[2];
104 int num_tokens;
105
106 const struct meson_i2c_data *data;
107 };
108
meson_i2c_set_mask(struct meson_i2c * i2c,int reg,u32 mask,u32 val)109 static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask,
110 u32 val)
111 {
112 u32 data;
113
114 data = readl(i2c->regs + reg);
115 data &= ~mask;
116 data |= val & mask;
117 writel(data, i2c->regs + reg);
118 }
119
meson_i2c_reset_tokens(struct meson_i2c * i2c)120 static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
121 {
122 i2c->tokens[0] = 0;
123 i2c->tokens[1] = 0;
124 i2c->num_tokens = 0;
125 }
126
meson_i2c_add_token(struct meson_i2c * i2c,int token)127 static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
128 {
129 if (i2c->num_tokens < 8)
130 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
131 else
132 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
133
134 i2c->num_tokens++;
135 }
136
meson_i2c_set_clk_div(struct meson_i2c * i2c,unsigned int freq)137 static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
138 {
139 unsigned long clk_rate = clk_get_rate(i2c->clk);
140 unsigned int div;
141
142 div = DIV_ROUND_UP(clk_rate, freq);
143 div -= FILTER_DELAY;
144 div = DIV_ROUND_UP(div, i2c->data->div_factor);
145
146 /* clock divider has 12 bits */
147 if (div > GENMASK(11, 0)) {
148 dev_err(i2c->dev, "requested bus frequency too low\n");
149 div = GENMASK(11, 0);
150 }
151
152 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV,
153 FIELD_PREP(REG_CTRL_CLKDIV, div & GENMASK(9, 0)));
154
155 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT,
156 FIELD_PREP(REG_CTRL_CLKDIVEXT, div >> 10));
157
158 /* Disable HIGH/LOW mode */
159 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_SCL_LOW_EN, 0);
160
161 dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
162 clk_rate, freq, div);
163 }
164
meson_i2c_get_data(struct meson_i2c * i2c,char * buf,int len)165 static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
166 {
167 u32 rdata0, rdata1;
168 int i;
169
170 rdata0 = readl(i2c->regs + REG_TOK_RDATA0);
171 rdata1 = readl(i2c->regs + REG_TOK_RDATA1);
172
173 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
174 rdata0, rdata1, len);
175
176 for (i = 0; i < min(4, len); i++)
177 *buf++ = (rdata0 >> i * 8) & 0xff;
178
179 for (i = 4; i < min(8, len); i++)
180 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
181 }
182
meson_i2c_put_data(struct meson_i2c * i2c,char * buf,int len)183 static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len)
184 {
185 u32 wdata0 = 0, wdata1 = 0;
186 int i;
187
188 for (i = 0; i < min(4, len); i++)
189 wdata0 |= *buf++ << (i * 8);
190
191 for (i = 4; i < min(8, len); i++)
192 wdata1 |= *buf++ << ((i - 4) * 8);
193
194 writel(wdata0, i2c->regs + REG_TOK_WDATA0);
195 writel(wdata1, i2c->regs + REG_TOK_WDATA1);
196
197 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
198 wdata0, wdata1, len);
199 }
200
meson_i2c_prepare_xfer(struct meson_i2c * i2c)201 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
202 {
203 bool write = !(i2c->msg->flags & I2C_M_RD);
204 int i;
205
206 i2c->count = min(i2c->msg->len - i2c->pos, 8);
207
208 for (i = 0; i < i2c->count - 1; i++)
209 meson_i2c_add_token(i2c, TOKEN_DATA);
210
211 if (i2c->count) {
212 if (write || i2c->pos + i2c->count < i2c->msg->len)
213 meson_i2c_add_token(i2c, TOKEN_DATA);
214 else
215 meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
216 }
217
218 if (write)
219 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
220
221 if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
222 meson_i2c_add_token(i2c, TOKEN_STOP);
223
224 writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
225 writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
226 }
227
meson_i2c_transfer_complete(struct meson_i2c * i2c,u32 ctrl)228 static void meson_i2c_transfer_complete(struct meson_i2c *i2c, u32 ctrl)
229 {
230 if (ctrl & REG_CTRL_ERROR) {
231 /*
232 * The bit is set when the IGNORE_NAK bit is cleared
233 * and the device didn't respond. In this case, the
234 * I2C controller automatically generates a STOP
235 * condition.
236 */
237 dev_dbg(i2c->dev, "error bit set\n");
238 i2c->error = -ENXIO;
239 i2c->state = STATE_IDLE;
240 } else {
241 if (i2c->state == STATE_READ && i2c->count)
242 meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
243 i2c->count);
244
245 i2c->pos += i2c->count;
246
247 if (i2c->pos >= i2c->msg->len)
248 i2c->state = STATE_IDLE;
249 }
250 }
251
meson_i2c_irq(int irqno,void * dev_id)252 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
253 {
254 struct meson_i2c *i2c = dev_id;
255 unsigned int ctrl;
256
257 spin_lock(&i2c->lock);
258
259 meson_i2c_reset_tokens(i2c);
260 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
261 ctrl = readl(i2c->regs + REG_CTRL);
262
263 dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
264 i2c->state, i2c->pos, i2c->count, ctrl);
265
266 if (i2c->state == STATE_IDLE) {
267 spin_unlock(&i2c->lock);
268 return IRQ_NONE;
269 }
270
271 meson_i2c_transfer_complete(i2c, ctrl);
272
273 if (i2c->state == STATE_IDLE) {
274 complete(&i2c->done);
275 goto out;
276 }
277
278 /* Restart the processing */
279 meson_i2c_prepare_xfer(i2c);
280 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
281 out:
282 spin_unlock(&i2c->lock);
283
284 return IRQ_HANDLED;
285 }
286
meson_i2c_do_start(struct meson_i2c * i2c,struct i2c_msg * msg)287 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
288 {
289 int token;
290
291 token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
292 TOKEN_SLAVE_ADDR_WRITE;
293
294
295 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR, REG_SLV_ADDR,
296 FIELD_PREP(REG_SLV_ADDR, msg->addr << 1));
297
298 meson_i2c_add_token(i2c, TOKEN_START);
299 meson_i2c_add_token(i2c, token);
300 }
301
meson_i2c_xfer_msg(struct meson_i2c * i2c,struct i2c_msg * msg,int last,bool atomic)302 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
303 int last, bool atomic)
304 {
305 unsigned long time_left, flags;
306 int ret = 0;
307 u32 ctrl;
308
309 i2c->msg = msg;
310 i2c->last = last;
311 i2c->pos = 0;
312 i2c->count = 0;
313 i2c->error = 0;
314
315 meson_i2c_reset_tokens(i2c);
316
317 flags = (msg->flags & I2C_M_IGNORE_NAK) ? REG_CTRL_ACK_IGNORE : 0;
318 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_ACK_IGNORE, flags);
319
320 if (!(msg->flags & I2C_M_NOSTART))
321 meson_i2c_do_start(i2c, msg);
322
323 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
324 meson_i2c_prepare_xfer(i2c);
325
326 if (!atomic)
327 reinit_completion(&i2c->done);
328
329 /* Start the transfer */
330 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
331
332 if (atomic) {
333 ret = readl_poll_timeout_atomic(i2c->regs + REG_CTRL, ctrl,
334 !(ctrl & REG_CTRL_STATUS),
335 10, I2C_TIMEOUT_MS * 1000);
336 } else {
337 time_left = msecs_to_jiffies(I2C_TIMEOUT_MS);
338 time_left = wait_for_completion_timeout(&i2c->done, time_left);
339
340 if (!time_left)
341 ret = -ETIMEDOUT;
342 }
343
344 /*
345 * Protect access to i2c struct and registers from interrupt
346 * handlers triggered by a transfer terminated after the
347 * timeout period
348 */
349 spin_lock_irqsave(&i2c->lock, flags);
350
351 if (atomic && !ret)
352 meson_i2c_transfer_complete(i2c, ctrl);
353
354 /* Abort any active operation */
355 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
356
357 if (ret)
358 i2c->state = STATE_IDLE;
359
360 if (i2c->error)
361 ret = i2c->error;
362
363 spin_unlock_irqrestore(&i2c->lock, flags);
364
365 return ret;
366 }
367
meson_i2c_xfer_messages(struct i2c_adapter * adap,struct i2c_msg * msgs,int num,bool atomic)368 static int meson_i2c_xfer_messages(struct i2c_adapter *adap,
369 struct i2c_msg *msgs, int num, bool atomic)
370 {
371 struct meson_i2c *i2c = adap->algo_data;
372 int i, ret = 0;
373
374 for (i = 0; i < num; i++) {
375 ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1, atomic);
376 if (ret)
377 break;
378 }
379
380 return ret ?: i;
381 }
382
meson_i2c_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)383 static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
384 int num)
385 {
386 return meson_i2c_xfer_messages(adap, msgs, num, false);
387 }
388
meson_i2c_xfer_atomic(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)389 static int meson_i2c_xfer_atomic(struct i2c_adapter *adap,
390 struct i2c_msg *msgs, int num)
391 {
392 return meson_i2c_xfer_messages(adap, msgs, num, true);
393 }
394
meson_i2c_func(struct i2c_adapter * adap)395 static u32 meson_i2c_func(struct i2c_adapter *adap)
396 {
397 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
398 }
399
400 static const struct i2c_algorithm meson_i2c_algorithm = {
401 .master_xfer = meson_i2c_xfer,
402 .master_xfer_atomic = meson_i2c_xfer_atomic,
403 .functionality = meson_i2c_func,
404 };
405
meson_i2c_probe(struct platform_device * pdev)406 static int meson_i2c_probe(struct platform_device *pdev)
407 {
408 struct device_node *np = pdev->dev.of_node;
409 struct meson_i2c *i2c;
410 struct i2c_timings timings;
411 int irq, ret = 0;
412
413 i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
414 if (!i2c)
415 return -ENOMEM;
416
417 i2c_parse_fw_timings(&pdev->dev, &timings, true);
418
419 i2c->dev = &pdev->dev;
420 platform_set_drvdata(pdev, i2c);
421
422 spin_lock_init(&i2c->lock);
423 init_completion(&i2c->done);
424
425 i2c->data = (const struct meson_i2c_data *)
426 of_device_get_match_data(&pdev->dev);
427
428 i2c->clk = devm_clk_get(&pdev->dev, NULL);
429 if (IS_ERR(i2c->clk)) {
430 dev_err(&pdev->dev, "can't get device clock\n");
431 return PTR_ERR(i2c->clk);
432 }
433
434 i2c->regs = devm_platform_ioremap_resource(pdev, 0);
435 if (IS_ERR(i2c->regs))
436 return PTR_ERR(i2c->regs);
437
438 irq = platform_get_irq(pdev, 0);
439 if (irq < 0)
440 return irq;
441
442 ret = devm_request_irq(&pdev->dev, irq, meson_i2c_irq, 0, NULL, i2c);
443 if (ret < 0) {
444 dev_err(&pdev->dev, "can't request IRQ\n");
445 return ret;
446 }
447
448 ret = clk_prepare_enable(i2c->clk);
449 if (ret < 0) {
450 dev_err(&pdev->dev, "can't prepare clock\n");
451 return ret;
452 }
453
454 strlcpy(i2c->adap.name, "Meson I2C adapter",
455 sizeof(i2c->adap.name));
456 i2c->adap.owner = THIS_MODULE;
457 i2c->adap.algo = &meson_i2c_algorithm;
458 i2c->adap.dev.parent = &pdev->dev;
459 i2c->adap.dev.of_node = np;
460 i2c->adap.algo_data = i2c;
461
462 /*
463 * A transfer is triggered when START bit changes from 0 to 1.
464 * Ensure that the bit is set to 0 after probe
465 */
466 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
467
468 ret = i2c_add_adapter(&i2c->adap);
469 if (ret < 0) {
470 clk_disable_unprepare(i2c->clk);
471 return ret;
472 }
473
474 /* Disable filtering */
475 meson_i2c_set_mask(i2c, REG_SLAVE_ADDR,
476 REG_SLV_SDA_FILTER | REG_SLV_SCL_FILTER, 0);
477
478 meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
479
480 return 0;
481 }
482
meson_i2c_remove(struct platform_device * pdev)483 static int meson_i2c_remove(struct platform_device *pdev)
484 {
485 struct meson_i2c *i2c = platform_get_drvdata(pdev);
486
487 i2c_del_adapter(&i2c->adap);
488 clk_disable_unprepare(i2c->clk);
489
490 return 0;
491 }
492
493 static const struct meson_i2c_data i2c_meson6_data = {
494 .div_factor = 4,
495 };
496
497 static const struct meson_i2c_data i2c_gxbb_data = {
498 .div_factor = 4,
499 };
500
501 static const struct meson_i2c_data i2c_axg_data = {
502 .div_factor = 3,
503 };
504
505 static const struct of_device_id meson_i2c_match[] = {
506 { .compatible = "amlogic,meson6-i2c", .data = &i2c_meson6_data },
507 { .compatible = "amlogic,meson-gxbb-i2c", .data = &i2c_gxbb_data },
508 { .compatible = "amlogic,meson-axg-i2c", .data = &i2c_axg_data },
509 {},
510 };
511
512 MODULE_DEVICE_TABLE(of, meson_i2c_match);
513
514 static struct platform_driver meson_i2c_driver = {
515 .probe = meson_i2c_probe,
516 .remove = meson_i2c_remove,
517 .driver = {
518 .name = "meson-i2c",
519 .of_match_table = meson_i2c_match,
520 },
521 };
522
523 module_platform_driver(meson_i2c_driver);
524
525 MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver");
526 MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
527 MODULE_LICENSE("GPL v2");
528
