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30021e37 BG |
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 | }; | |
93ae9650 | 478 | MODULE_DEVICE_TABLE(of, meson_i2c_match); |
30021e37 BG |
479 | |
480 | static struct platform_driver meson_i2c_driver = { | |
481 | .probe = meson_i2c_probe, | |
482 | .remove = meson_i2c_remove, | |
483 | .driver = { | |
484 | .name = "meson-i2c", | |
485 | .of_match_table = meson_i2c_match, | |
486 | }, | |
487 | }; | |
488 | ||
489 | module_platform_driver(meson_i2c_driver); | |
490 | ||
491 | MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver"); | |
492 | MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>"); | |
493 | MODULE_LICENSE("GPL v2"); |