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3f9c37a0 JE |
1 | /* |
2 | * Copyright (C) 2011 NXP Semiconductors | |
3 | * | |
4 | * Code portions referenced from the i2x-pxa and i2c-pnx drivers | |
5 | * | |
6 | * Make SMBus byte and word transactions work on LPC178x/7x | |
7 | * Copyright (c) 2012 | |
8 | * Alexander Potashev, Emcraft Systems, aspotashev@emcraft.com | |
9 | * Anton Protopopov, Emcraft Systems, antonp@emcraft.com | |
10 | * | |
11 | * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com> | |
12 | * | |
13 | * This program is free software; you can redistribute it and/or modify | |
14 | * it under the terms of the GNU General Public License as published by | |
15 | * the Free Software Foundation; either version 2 of the License, or | |
16 | * (at your option) any later version. | |
17 | * | |
18 | */ | |
19 | ||
20 | #include <linux/clk.h> | |
21 | #include <linux/errno.h> | |
22 | #include <linux/i2c.h> | |
23 | #include <linux/interrupt.h> | |
24 | #include <linux/io.h> | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/of.h> | |
28 | #include <linux/of_device.h> | |
29 | #include <linux/platform_device.h> | |
30 | #include <linux/sched.h> | |
31 | #include <linux/time.h> | |
32 | ||
33 | /* LPC24xx register offsets and bits */ | |
34 | #define LPC24XX_I2CONSET 0x00 | |
35 | #define LPC24XX_I2STAT 0x04 | |
36 | #define LPC24XX_I2DAT 0x08 | |
37 | #define LPC24XX_I2ADDR 0x0c | |
38 | #define LPC24XX_I2SCLH 0x10 | |
39 | #define LPC24XX_I2SCLL 0x14 | |
40 | #define LPC24XX_I2CONCLR 0x18 | |
41 | ||
42 | #define LPC24XX_AA BIT(2) | |
43 | #define LPC24XX_SI BIT(3) | |
44 | #define LPC24XX_STO BIT(4) | |
45 | #define LPC24XX_STA BIT(5) | |
46 | #define LPC24XX_I2EN BIT(6) | |
47 | ||
48 | #define LPC24XX_STO_AA (LPC24XX_STO | LPC24XX_AA) | |
49 | #define LPC24XX_CLEAR_ALL (LPC24XX_AA | LPC24XX_SI | LPC24XX_STO | \ | |
50 | LPC24XX_STA | LPC24XX_I2EN) | |
51 | ||
52 | /* I2C SCL clock has different duty cycle depending on mode */ | |
53 | #define I2C_STD_MODE_DUTY 46 | |
54 | #define I2C_FAST_MODE_DUTY 36 | |
55 | #define I2C_FAST_MODE_PLUS_DUTY 38 | |
56 | ||
57 | /* | |
58 | * 26 possible I2C status codes, but codes applicable only | |
59 | * to master are listed here and used in this driver | |
60 | */ | |
61 | enum { | |
62 | M_BUS_ERROR = 0x00, | |
63 | M_START = 0x08, | |
64 | M_REPSTART = 0x10, | |
65 | MX_ADDR_W_ACK = 0x18, | |
66 | MX_ADDR_W_NACK = 0x20, | |
67 | MX_DATA_W_ACK = 0x28, | |
68 | MX_DATA_W_NACK = 0x30, | |
69 | M_DATA_ARB_LOST = 0x38, | |
70 | MR_ADDR_R_ACK = 0x40, | |
71 | MR_ADDR_R_NACK = 0x48, | |
72 | MR_DATA_R_ACK = 0x50, | |
73 | MR_DATA_R_NACK = 0x58, | |
74 | M_I2C_IDLE = 0xf8, | |
75 | }; | |
76 | ||
77 | struct lpc2k_i2c { | |
78 | void __iomem *base; | |
79 | struct clk *clk; | |
80 | int irq; | |
81 | wait_queue_head_t wait; | |
82 | struct i2c_adapter adap; | |
83 | struct i2c_msg *msg; | |
84 | int msg_idx; | |
85 | int msg_status; | |
86 | int is_last; | |
87 | }; | |
88 | ||
89 | static void i2c_lpc2k_reset(struct lpc2k_i2c *i2c) | |
90 | { | |
91 | /* Will force clear all statuses */ | |
92 | writel(LPC24XX_CLEAR_ALL, i2c->base + LPC24XX_I2CONCLR); | |
93 | writel(0, i2c->base + LPC24XX_I2ADDR); | |
94 | writel(LPC24XX_I2EN, i2c->base + LPC24XX_I2CONSET); | |
95 | } | |
96 | ||
97 | static int i2c_lpc2k_clear_arb(struct lpc2k_i2c *i2c) | |
98 | { | |
99 | unsigned long timeout = jiffies + msecs_to_jiffies(1000); | |
100 | ||
101 | /* | |
102 | * If the transfer needs to abort for some reason, we'll try to | |
103 | * force a stop condition to clear any pending bus conditions | |
104 | */ | |
105 | writel(LPC24XX_STO, i2c->base + LPC24XX_I2CONSET); | |
106 | ||
107 | /* Wait for status change */ | |
108 | while (readl(i2c->base + LPC24XX_I2STAT) != M_I2C_IDLE) { | |
109 | if (time_after(jiffies, timeout)) { | |
110 | /* Bus was not idle, try to reset adapter */ | |
111 | i2c_lpc2k_reset(i2c); | |
112 | return -EBUSY; | |
113 | } | |
114 | ||
115 | cpu_relax(); | |
116 | } | |
117 | ||
118 | return 0; | |
119 | } | |
120 | ||
121 | static void i2c_lpc2k_pump_msg(struct lpc2k_i2c *i2c) | |
122 | { | |
123 | unsigned char data; | |
124 | u32 status; | |
125 | ||
126 | /* | |
127 | * I2C in the LPC2xxx series is basically a state machine. | |
128 | * Just run through the steps based on the current status. | |
129 | */ | |
130 | status = readl(i2c->base + LPC24XX_I2STAT); | |
131 | ||
132 | switch (status) { | |
133 | case M_START: | |
134 | case M_REPSTART: | |
135 | /* Start bit was just sent out, send out addr and dir */ | |
043f47f4 | 136 | data = i2c_8bit_addr_from_msg(i2c->msg); |
3f9c37a0 JE |
137 | |
138 | writel(data, i2c->base + LPC24XX_I2DAT); | |
139 | writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR); | |
140 | break; | |
141 | ||
142 | case MX_ADDR_W_ACK: | |
143 | case MX_DATA_W_ACK: | |
144 | /* | |
145 | * Address or data was sent out with an ACK. If there is more | |
146 | * data to send, send it now | |
147 | */ | |
148 | if (i2c->msg_idx < i2c->msg->len) { | |
149 | writel(i2c->msg->buf[i2c->msg_idx], | |
150 | i2c->base + LPC24XX_I2DAT); | |
151 | } else if (i2c->is_last) { | |
152 | /* Last message, send stop */ | |
153 | writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET); | |
154 | writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); | |
155 | i2c->msg_status = 0; | |
156 | disable_irq_nosync(i2c->irq); | |
157 | } else { | |
158 | i2c->msg_status = 0; | |
159 | disable_irq_nosync(i2c->irq); | |
160 | } | |
161 | ||
162 | i2c->msg_idx++; | |
163 | break; | |
164 | ||
165 | case MR_ADDR_R_ACK: | |
166 | /* Receive first byte from slave */ | |
167 | if (i2c->msg->len == 1) { | |
168 | /* Last byte, return NACK */ | |
169 | writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR); | |
170 | } else { | |
171 | /* Not last byte, return ACK */ | |
172 | writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET); | |
173 | } | |
174 | ||
175 | writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR); | |
176 | break; | |
177 | ||
178 | case MR_DATA_R_NACK: | |
179 | /* | |
180 | * The I2C shows NACK status on reads, so we need to accept | |
181 | * the NACK as an ACK here. This should be ok, as the real | |
182 | * BACK would of been caught on the address write. | |
183 | */ | |
184 | case MR_DATA_R_ACK: | |
185 | /* Data was received */ | |
186 | if (i2c->msg_idx < i2c->msg->len) { | |
187 | i2c->msg->buf[i2c->msg_idx] = | |
188 | readl(i2c->base + LPC24XX_I2DAT); | |
189 | } | |
190 | ||
191 | /* If transfer is done, send STOP */ | |
192 | if (i2c->msg_idx >= i2c->msg->len - 1 && i2c->is_last) { | |
193 | writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET); | |
194 | writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); | |
195 | i2c->msg_status = 0; | |
196 | } | |
197 | ||
198 | /* Message is done */ | |
199 | if (i2c->msg_idx >= i2c->msg->len - 1) { | |
200 | i2c->msg_status = 0; | |
201 | disable_irq_nosync(i2c->irq); | |
202 | } | |
203 | ||
204 | /* | |
205 | * One pre-last data input, send NACK to tell the slave that | |
206 | * this is going to be the last data byte to be transferred. | |
207 | */ | |
208 | if (i2c->msg_idx >= i2c->msg->len - 2) { | |
209 | /* One byte left to receive - NACK */ | |
210 | writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR); | |
211 | } else { | |
212 | /* More than one byte left to receive - ACK */ | |
213 | writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET); | |
214 | } | |
215 | ||
216 | writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR); | |
217 | i2c->msg_idx++; | |
218 | break; | |
219 | ||
220 | case MX_ADDR_W_NACK: | |
221 | case MX_DATA_W_NACK: | |
222 | case MR_ADDR_R_NACK: | |
223 | /* NACK processing is done */ | |
224 | writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET); | |
225 | i2c->msg_status = -ENXIO; | |
226 | disable_irq_nosync(i2c->irq); | |
227 | break; | |
228 | ||
229 | case M_DATA_ARB_LOST: | |
230 | /* Arbitration lost */ | |
231 | i2c->msg_status = -EAGAIN; | |
232 | ||
233 | /* Release the I2C bus */ | |
234 | writel(LPC24XX_STA | LPC24XX_STO, i2c->base + LPC24XX_I2CONCLR); | |
235 | disable_irq_nosync(i2c->irq); | |
236 | break; | |
237 | ||
238 | default: | |
239 | /* Unexpected statuses */ | |
240 | i2c->msg_status = -EIO; | |
241 | disable_irq_nosync(i2c->irq); | |
242 | break; | |
243 | } | |
244 | ||
245 | /* Exit on failure or all bytes transferred */ | |
246 | if (i2c->msg_status != -EBUSY) | |
247 | wake_up(&i2c->wait); | |
248 | ||
249 | /* | |
250 | * If `msg_status` is zero, then `lpc2k_process_msg()` | |
251 | * is responsible for clearing the SI flag. | |
252 | */ | |
253 | if (i2c->msg_status != 0) | |
254 | writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); | |
255 | } | |
256 | ||
257 | static int lpc2k_process_msg(struct lpc2k_i2c *i2c, int msgidx) | |
258 | { | |
259 | /* A new transfer is kicked off by initiating a start condition */ | |
260 | if (!msgidx) { | |
261 | writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET); | |
262 | } else { | |
263 | /* | |
264 | * A multi-message I2C transfer continues where the | |
265 | * previous I2C transfer left off and uses the | |
266 | * current condition of the I2C adapter. | |
267 | */ | |
268 | if (unlikely(i2c->msg->flags & I2C_M_NOSTART)) { | |
269 | WARN_ON(i2c->msg->len == 0); | |
270 | ||
271 | if (!(i2c->msg->flags & I2C_M_RD)) { | |
272 | /* Start transmit of data */ | |
273 | writel(i2c->msg->buf[0], | |
274 | i2c->base + LPC24XX_I2DAT); | |
275 | i2c->msg_idx++; | |
276 | } | |
277 | } else { | |
278 | /* Start or repeated start */ | |
279 | writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET); | |
280 | } | |
281 | ||
282 | writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR); | |
283 | } | |
284 | ||
285 | enable_irq(i2c->irq); | |
286 | ||
287 | /* Wait for transfer completion */ | |
288 | if (wait_event_timeout(i2c->wait, i2c->msg_status != -EBUSY, | |
289 | msecs_to_jiffies(1000)) == 0) { | |
290 | disable_irq_nosync(i2c->irq); | |
291 | ||
292 | return -ETIMEDOUT; | |
293 | } | |
294 | ||
295 | return i2c->msg_status; | |
296 | } | |
297 | ||
298 | static int i2c_lpc2k_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, | |
299 | int msg_num) | |
300 | { | |
301 | struct lpc2k_i2c *i2c = i2c_get_adapdata(adap); | |
302 | int ret, i; | |
303 | u32 stat; | |
304 | ||
305 | /* Check for bus idle condition */ | |
306 | stat = readl(i2c->base + LPC24XX_I2STAT); | |
307 | if (stat != M_I2C_IDLE) { | |
308 | /* Something is holding the bus, try to clear it */ | |
309 | return i2c_lpc2k_clear_arb(i2c); | |
310 | } | |
311 | ||
312 | /* Process a single message at a time */ | |
313 | for (i = 0; i < msg_num; i++) { | |
314 | /* Save message pointer and current message data index */ | |
315 | i2c->msg = &msgs[i]; | |
316 | i2c->msg_idx = 0; | |
317 | i2c->msg_status = -EBUSY; | |
318 | i2c->is_last = (i == (msg_num - 1)); | |
319 | ||
320 | ret = lpc2k_process_msg(i2c, i); | |
321 | if (ret) | |
322 | return ret; | |
323 | } | |
324 | ||
325 | return msg_num; | |
326 | } | |
327 | ||
328 | static irqreturn_t i2c_lpc2k_handler(int irq, void *dev_id) | |
329 | { | |
330 | struct lpc2k_i2c *i2c = dev_id; | |
331 | ||
332 | if (readl(i2c->base + LPC24XX_I2CONSET) & LPC24XX_SI) { | |
333 | i2c_lpc2k_pump_msg(i2c); | |
334 | return IRQ_HANDLED; | |
335 | } | |
336 | ||
337 | return IRQ_NONE; | |
338 | } | |
339 | ||
340 | static u32 i2c_lpc2k_functionality(struct i2c_adapter *adap) | |
341 | { | |
342 | /* Only emulated SMBus for now */ | |
343 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; | |
344 | } | |
345 | ||
346 | static const struct i2c_algorithm i2c_lpc2k_algorithm = { | |
347 | .master_xfer = i2c_lpc2k_xfer, | |
348 | .functionality = i2c_lpc2k_functionality, | |
349 | }; | |
350 | ||
351 | static int i2c_lpc2k_probe(struct platform_device *pdev) | |
352 | { | |
353 | struct lpc2k_i2c *i2c; | |
354 | struct resource *res; | |
355 | u32 bus_clk_rate; | |
356 | u32 scl_high; | |
357 | u32 clkrate; | |
358 | int ret; | |
359 | ||
360 | i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL); | |
361 | if (!i2c) | |
362 | return -ENOMEM; | |
363 | ||
364 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
365 | i2c->base = devm_ioremap_resource(&pdev->dev, res); | |
366 | if (IS_ERR(i2c->base)) | |
367 | return PTR_ERR(i2c->base); | |
368 | ||
369 | i2c->irq = platform_get_irq(pdev, 0); | |
370 | if (i2c->irq < 0) { | |
371 | dev_err(&pdev->dev, "can't get interrupt resource\n"); | |
372 | return i2c->irq; | |
373 | } | |
374 | ||
375 | init_waitqueue_head(&i2c->wait); | |
376 | ||
377 | i2c->clk = devm_clk_get(&pdev->dev, NULL); | |
378 | if (IS_ERR(i2c->clk)) { | |
379 | dev_err(&pdev->dev, "error getting clock\n"); | |
380 | return PTR_ERR(i2c->clk); | |
381 | } | |
382 | ||
383 | ret = clk_prepare_enable(i2c->clk); | |
384 | if (ret) { | |
385 | dev_err(&pdev->dev, "unable to enable clock.\n"); | |
386 | return ret; | |
387 | } | |
388 | ||
389 | ret = devm_request_irq(&pdev->dev, i2c->irq, i2c_lpc2k_handler, 0, | |
390 | dev_name(&pdev->dev), i2c); | |
391 | if (ret < 0) { | |
392 | dev_err(&pdev->dev, "can't request interrupt.\n"); | |
393 | goto fail_clk; | |
394 | } | |
395 | ||
396 | disable_irq_nosync(i2c->irq); | |
397 | ||
398 | /* Place controller is a known state */ | |
399 | i2c_lpc2k_reset(i2c); | |
400 | ||
401 | ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", | |
402 | &bus_clk_rate); | |
403 | if (ret) | |
404 | bus_clk_rate = 100000; /* 100 kHz default clock rate */ | |
405 | ||
406 | clkrate = clk_get_rate(i2c->clk); | |
407 | if (clkrate == 0) { | |
408 | dev_err(&pdev->dev, "can't get I2C base clock\n"); | |
409 | ret = -EINVAL; | |
410 | goto fail_clk; | |
411 | } | |
412 | ||
413 | /* Setup I2C dividers to generate clock with proper duty cycle */ | |
414 | clkrate = clkrate / bus_clk_rate; | |
415 | if (bus_clk_rate <= 100000) | |
416 | scl_high = (clkrate * I2C_STD_MODE_DUTY) / 100; | |
417 | else if (bus_clk_rate <= 400000) | |
418 | scl_high = (clkrate * I2C_FAST_MODE_DUTY) / 100; | |
419 | else | |
420 | scl_high = (clkrate * I2C_FAST_MODE_PLUS_DUTY) / 100; | |
421 | ||
422 | writel(scl_high, i2c->base + LPC24XX_I2SCLH); | |
423 | writel(clkrate - scl_high, i2c->base + LPC24XX_I2SCLL); | |
424 | ||
425 | platform_set_drvdata(pdev, i2c); | |
426 | ||
427 | i2c_set_adapdata(&i2c->adap, i2c); | |
428 | i2c->adap.owner = THIS_MODULE; | |
429 | strlcpy(i2c->adap.name, "LPC2K I2C adapter", sizeof(i2c->adap.name)); | |
430 | i2c->adap.algo = &i2c_lpc2k_algorithm; | |
431 | i2c->adap.dev.parent = &pdev->dev; | |
432 | i2c->adap.dev.of_node = pdev->dev.of_node; | |
433 | ||
434 | ret = i2c_add_adapter(&i2c->adap); | |
ea734404 | 435 | if (ret < 0) |
3f9c37a0 | 436 | goto fail_clk; |
3f9c37a0 JE |
437 | |
438 | dev_info(&pdev->dev, "LPC2K I2C adapter\n"); | |
439 | ||
440 | return 0; | |
441 | ||
442 | fail_clk: | |
443 | clk_disable_unprepare(i2c->clk); | |
444 | return ret; | |
445 | } | |
446 | ||
447 | static int i2c_lpc2k_remove(struct platform_device *dev) | |
448 | { | |
449 | struct lpc2k_i2c *i2c = platform_get_drvdata(dev); | |
450 | ||
451 | i2c_del_adapter(&i2c->adap); | |
452 | clk_disable_unprepare(i2c->clk); | |
453 | ||
454 | return 0; | |
455 | } | |
456 | ||
457 | #ifdef CONFIG_PM | |
458 | static int i2c_lpc2k_suspend(struct device *dev) | |
459 | { | |
460 | struct platform_device *pdev = to_platform_device(dev); | |
461 | struct lpc2k_i2c *i2c = platform_get_drvdata(pdev); | |
462 | ||
463 | clk_disable(i2c->clk); | |
464 | ||
465 | return 0; | |
466 | } | |
467 | ||
468 | static int i2c_lpc2k_resume(struct device *dev) | |
469 | { | |
470 | struct platform_device *pdev = to_platform_device(dev); | |
471 | struct lpc2k_i2c *i2c = platform_get_drvdata(pdev); | |
472 | ||
473 | clk_enable(i2c->clk); | |
474 | i2c_lpc2k_reset(i2c); | |
475 | ||
476 | return 0; | |
477 | } | |
478 | ||
479 | static const struct dev_pm_ops i2c_lpc2k_dev_pm_ops = { | |
480 | .suspend_noirq = i2c_lpc2k_suspend, | |
481 | .resume_noirq = i2c_lpc2k_resume, | |
482 | }; | |
483 | ||
484 | #define I2C_LPC2K_DEV_PM_OPS (&i2c_lpc2k_dev_pm_ops) | |
485 | #else | |
486 | #define I2C_LPC2K_DEV_PM_OPS NULL | |
487 | #endif | |
488 | ||
489 | static const struct of_device_id lpc2k_i2c_match[] = { | |
490 | { .compatible = "nxp,lpc1788-i2c" }, | |
491 | {}, | |
492 | }; | |
493 | MODULE_DEVICE_TABLE(of, lpc2k_i2c_match); | |
494 | ||
495 | static struct platform_driver i2c_lpc2k_driver = { | |
496 | .probe = i2c_lpc2k_probe, | |
497 | .remove = i2c_lpc2k_remove, | |
498 | .driver = { | |
499 | .name = "lpc2k-i2c", | |
500 | .pm = I2C_LPC2K_DEV_PM_OPS, | |
501 | .of_match_table = lpc2k_i2c_match, | |
502 | }, | |
503 | }; | |
504 | module_platform_driver(i2c_lpc2k_driver); | |
505 | ||
506 | MODULE_AUTHOR("Kevin Wells <kevin.wells@nxp.com>"); | |
507 | MODULE_DESCRIPTION("I2C driver for LPC2xxx devices"); | |
508 | MODULE_LICENSE("GPL"); | |
509 | MODULE_ALIAS("platform:lpc2k-i2c"); |