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Linux 4.1.16
[linux/fpc-iii.git] / drivers / i2c / busses / i2c-meson.c
blob5e176adca8e8a7b4326f2aa3d95c6188cb15ff16
1 /*
2 * I2C bus driver for Amlogic Meson SoCs
3 *
4 * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11 #include <linux/clk.h>
12 #include <linux/completion.h>
13 #include <linux/i2c.h>
14 #include <linux/interrupt.h>
15 #include <linux/io.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/of.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_SHIFT 12
38 #define REG_CTRL_CLKDIV_MASK ((BIT(10) - 1) << REG_CTRL_CLKDIV_SHIFT)
39
40 #define I2C_TIMEOUT_MS 500
41 #define DEFAULT_FREQ 100000
42
43 enum {
44 TOKEN_END = 0,
45 TOKEN_START,
46 TOKEN_SLAVE_ADDR_WRITE,
47 TOKEN_SLAVE_ADDR_READ,
48 TOKEN_DATA,
49 TOKEN_DATA_LAST,
50 TOKEN_STOP,
51 };
52
53 enum {
54 STATE_IDLE,
55 STATE_READ,
56 STATE_WRITE,
57 STATE_STOP,
58 };
59
60 /**
61 * struct meson_i2c - Meson I2C device private data
62 *
63 * @adap: I2C adapter instance
64 * @dev: Pointer to device structure
65 * @regs: Base address of the device memory mapped registers
66 * @clk: Pointer to clock structure
67 * @irq: IRQ number
68 * @msg: Pointer to the current I2C message
69 * @state: Current state in the driver state machine
70 * @last: Flag set for the last message in the transfer
71 * @count: Number of bytes to be sent/received in current transfer
72 * @pos: Current position in the send/receive buffer
73 * @error: Flag set when an error is received
74 * @lock: To avoid race conditions between irq handler and xfer code
75 * @done: Completion used to wait for transfer termination
76 * @frequency: Operating frequency of I2C bus clock
77 * @tokens: Sequence of tokens to be written to the device
78 * @num_tokens: Number of tokens
79 */
80 struct meson_i2c {
81 struct i2c_adapter adap;
82 struct device *dev;
83 void __iomem *regs;
84 struct clk *clk;
85 int irq;
86
87 struct i2c_msg *msg;
88 int state;
89 bool last;
90 int count;
91 int pos;
92 int error;
93
94 spinlock_t lock;
95 struct completion done;
96 unsigned int frequency;
97 u32 tokens[2];
98 int num_tokens;
99 };
100
101 static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask,
102 u32 val)
103 {
104 u32 data;
105
106 data = readl(i2c->regs + reg);
107 data &= ~mask;
108 data |= val & mask;
109 writel(data, i2c->regs + reg);
110 }
111
112 static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
113 {
114 i2c->tokens[0] = 0;
115 i2c->tokens[1] = 0;
116 i2c->num_tokens = 0;
117 }
118
119 static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
120 {
121 if (i2c->num_tokens < 8)
122 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
123 else
124 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
125
126 i2c->num_tokens++;
127 }
128
129 static void meson_i2c_write_tokens(struct meson_i2c *i2c)
130 {
131 writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
132 writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
133 }
134
135 static void meson_i2c_set_clk_div(struct meson_i2c *i2c)
136 {
137 unsigned long clk_rate = clk_get_rate(i2c->clk);
138 unsigned int div;
139
140 div = DIV_ROUND_UP(clk_rate, i2c->frequency * 4);
141 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
142 div << REG_CTRL_CLKDIV_SHIFT);
143
144 dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
145 clk_rate, i2c->frequency, div);
146 }
147
148 static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
149 {
150 u32 rdata0, rdata1;
151 int i;
152
153 rdata0 = readl(i2c->regs + REG_TOK_RDATA0);
154 rdata1 = readl(i2c->regs + REG_TOK_RDATA1);
155
156 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
157 rdata0, rdata1, len);
158
159 for (i = 0; i < min_t(int, 4, len); i++)
160 *buf++ = (rdata0 >> i * 8) & 0xff;
161
162 for (i = 4; i < min_t(int, 8, len); i++)
163 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
164 }
165
166 static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len)
167 {
168 u32 wdata0 = 0, wdata1 = 0;
169 int i;
170
171 for (i = 0; i < min_t(int, 4, len); i++)
172 wdata0 |= *buf++ << (i * 8);
173
174 for (i = 4; i < min_t(int, 8, len); i++)
175 wdata1 |= *buf++ << ((i - 4) * 8);
176
177 writel(wdata0, i2c->regs + REG_TOK_WDATA0);
178 writel(wdata0, i2c->regs + REG_TOK_WDATA1);
179
180 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
181 wdata0, wdata1, len);
182 }
183
184 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
185 {
186 bool write = !(i2c->msg->flags & I2C_M_RD);
187 int i;
188
189 i2c->count = min_t(int, i2c->msg->len - i2c->pos, 8);
190
191 for (i = 0; i < i2c->count - 1; i++)
192 meson_i2c_add_token(i2c, TOKEN_DATA);
193
194 if (i2c->count) {
195 if (write || i2c->pos + i2c->count < i2c->msg->len)
196 meson_i2c_add_token(i2c, TOKEN_DATA);
197 else
198 meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
199 }
200
201 if (write)
202 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
203 }
204
205 static void meson_i2c_stop(struct meson_i2c *i2c)
206 {
207 dev_dbg(i2c->dev, "%s: last %d\n", __func__, i2c->last);
208
209 if (i2c->last) {
210 i2c->state = STATE_STOP;
211 meson_i2c_add_token(i2c, TOKEN_STOP);
212 } else {
213 i2c->state = STATE_IDLE;
214 complete_all(&i2c->done);
215 }
216 }
217
218 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
219 {
220 struct meson_i2c *i2c = dev_id;
221 unsigned int ctrl;
222
223 spin_lock(&i2c->lock);
224
225 meson_i2c_reset_tokens(i2c);
226 ctrl = readl(i2c->regs + REG_CTRL);
227
228 dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
229 i2c->state, i2c->pos, i2c->count, ctrl);
230
231 if (ctrl & REG_CTRL_ERROR && i2c->state != STATE_IDLE) {
232 /*
233 * The bit is set when the IGNORE_NAK bit is cleared
234 * and the device didn't respond. In this case, the
235 * I2C controller automatically generates a STOP
236 * condition.
237 */
238 dev_dbg(i2c->dev, "error bit set\n");
239 i2c->error = -ENXIO;
240 i2c->state = STATE_IDLE;
241 complete_all(&i2c->done);
242 goto out;
243 }
244
245 switch (i2c->state) {
246 case STATE_READ:
247 if (i2c->count > 0) {
248 meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
249 i2c->count);
250 i2c->pos += i2c->count;
251 }
252
253 if (i2c->pos >= i2c->msg->len) {
254 meson_i2c_stop(i2c);
255 break;
256 }
257
258 meson_i2c_prepare_xfer(i2c);
259 break;
260 case STATE_WRITE:
261 i2c->pos += i2c->count;
262
263 if (i2c->pos >= i2c->msg->len) {
264 meson_i2c_stop(i2c);
265 break;
266 }
267
268 meson_i2c_prepare_xfer(i2c);
269 break;
270 case STATE_STOP:
271 i2c->state = STATE_IDLE;
272 complete_all(&i2c->done);
273 break;
274 case STATE_IDLE:
275 break;
276 }
277
278 out:
279 if (i2c->state != STATE_IDLE) {
280 /* Restart the processing */
281 meson_i2c_write_tokens(i2c);
282 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
283 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START,
284 REG_CTRL_START);
285 }
286
287 spin_unlock(&i2c->lock);
288
289 return IRQ_HANDLED;
290 }
291
292 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
293 {
294 int token;
295
296 token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
297 TOKEN_SLAVE_ADDR_WRITE;
298
299 writel(msg->addr << 1, i2c->regs + REG_SLAVE_ADDR);
300 meson_i2c_add_token(i2c, TOKEN_START);
301 meson_i2c_add_token(i2c, token);
302 }
303
304 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
305 int last)
306 {
307 unsigned long time_left, flags;
308 int ret = 0;
309
310 i2c->msg = msg;
311 i2c->last = last;
312 i2c->pos = 0;
313 i2c->count = 0;
314 i2c->error = 0;
315
316 meson_i2c_reset_tokens(i2c);
317
318 flags = (msg->flags & I2C_M_IGNORE_NAK) ? REG_CTRL_ACK_IGNORE : 0;
319 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_ACK_IGNORE, flags);
320
321 if (!(msg->flags & I2C_M_NOSTART))
322 meson_i2c_do_start(i2c, msg);
323
324 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
325 meson_i2c_prepare_xfer(i2c);
326 meson_i2c_write_tokens(i2c);
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 time_left = msecs_to_jiffies(I2C_TIMEOUT_MS);
333 time_left = wait_for_completion_timeout(&i2c->done, time_left);
334
335 /*
336 * Protect access to i2c struct and registers from interrupt
337 * handlers triggered by a transfer terminated after the
338 * timeout period
339 */
340 spin_lock_irqsave(&i2c->lock, flags);
341
342 /* Abort any active operation */
343 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
344
345 if (!time_left) {
346 i2c->state = STATE_IDLE;
347 ret = -ETIMEDOUT;
348 }
349
350 if (i2c->error)
351 ret = i2c->error;
352
353 spin_unlock_irqrestore(&i2c->lock, flags);
354
355 return ret;
356 }
357
358 static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
359 int num)
360 {
361 struct meson_i2c *i2c = adap->algo_data;
362 int i, ret = 0, count = 0;
363
364 clk_enable(i2c->clk);
365 meson_i2c_set_clk_div(i2c);
366
367 for (i = 0; i < num; i++) {
368 ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1);
369 if (ret)
370 break;
371 count++;
372 }
373
374 clk_disable(i2c->clk);
375
376 return ret ? ret : count;
377 }
378
379 static u32 meson_i2c_func(struct i2c_adapter *adap)
380 {
381 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
382 }
383
384 static const struct i2c_algorithm meson_i2c_algorithm = {
385 .master_xfer = meson_i2c_xfer,
386 .functionality = meson_i2c_func,
387 };
388
389 static int meson_i2c_probe(struct platform_device *pdev)
390 {
391 struct device_node *np = pdev->dev.of_node;
392 struct meson_i2c *i2c;
393 struct resource *mem;
394 int ret = 0;
395
396 i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
397 if (!i2c)
398 return -ENOMEM;
399
400 if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
401 &i2c->frequency))
402 i2c->frequency = DEFAULT_FREQ;
403
404 i2c->dev = &pdev->dev;
405 platform_set_drvdata(pdev, i2c);
406
407 spin_lock_init(&i2c->lock);
408 init_completion(&i2c->done);
409
410 i2c->clk = devm_clk_get(&pdev->dev, NULL);
411 if (IS_ERR(i2c->clk)) {
412 dev_err(&pdev->dev, "can't get device clock\n");
413 return PTR_ERR(i2c->clk);
414 }
415
416 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
417 i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
418 if (IS_ERR(i2c->regs))
419 return PTR_ERR(i2c->regs);
420
421 i2c->irq = platform_get_irq(pdev, 0);
422 if (i2c->irq < 0) {
423 dev_err(&pdev->dev, "can't find IRQ\n");
424 return i2c->irq;
425 }
426
427 ret = devm_request_irq(&pdev->dev, i2c->irq, meson_i2c_irq,
428 0, dev_name(&pdev->dev), i2c);
429 if (ret < 0) {
430 dev_err(&pdev->dev, "can't request IRQ\n");
431 return ret;
432 }
433
434 ret = clk_prepare(i2c->clk);
435 if (ret < 0) {
436 dev_err(&pdev->dev, "can't prepare clock\n");
437 return ret;
438 }
439
440 strlcpy(i2c->adap.name, "Meson I2C adapter",
441 sizeof(i2c->adap.name));
442 i2c->adap.owner = THIS_MODULE;
443 i2c->adap.algo = &meson_i2c_algorithm;
444 i2c->adap.dev.parent = &pdev->dev;
445 i2c->adap.dev.of_node = np;
446 i2c->adap.algo_data = i2c;
447
448 /*
449 * A transfer is triggered when START bit changes from 0 to 1.
450 * Ensure that the bit is set to 0 after probe
451 */
452 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
453
454 ret = i2c_add_adapter(&i2c->adap);
455 if (ret < 0) {
456 dev_err(&pdev->dev, "can't register adapter\n");
457 clk_unprepare(i2c->clk);
458 return ret;
459 }
460
461 return 0;
462 }
463
464 static int meson_i2c_remove(struct platform_device *pdev)
465 {
466 struct meson_i2c *i2c = platform_get_drvdata(pdev);
467
468 i2c_del_adapter(&i2c->adap);
469 clk_unprepare(i2c->clk);
470
471 return 0;
472 }
473
474 static const struct of_device_id meson_i2c_match[] = {
475 { .compatible = "amlogic,meson6-i2c" },
476 { },
477 };
478
479 static struct platform_driver meson_i2c_driver = {
480 .probe = meson_i2c_probe,
481 .remove = meson_i2c_remove,
482 .driver = {
483 .name = "meson-i2c",
484 .of_match_table = meson_i2c_match,
485 },
486 };
487
488 module_platform_driver(meson_i2c_driver);
489
490 MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver");
491 MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
492 MODULE_LICENSE("GPL v2");
Linux with added FPC-III support