xref: /openbmc/linux/drivers/i2c/busses/i2c-davinci.c (revision 9ac8d3fb)
1 /*
2  * TI DAVINCI I2C adapter driver.
3  *
4  * Copyright (C) 2006 Texas Instruments.
5  * Copyright (C) 2007 MontaVista Software Inc.
6  *
7  * Updated by Vinod & Sudhakar Feb 2005
8  *
9  * ----------------------------------------------------------------------------
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24  * ----------------------------------------------------------------------------
25  *
26  */
27 #include <linux/kernel.h>
28 #include <linux/module.h>
29 #include <linux/delay.h>
30 #include <linux/i2c.h>
31 #include <linux/clk.h>
32 #include <linux/errno.h>
33 #include <linux/sched.h>
34 #include <linux/err.h>
35 #include <linux/interrupt.h>
36 #include <linux/platform_device.h>
37 #include <linux/io.h>
38 
39 #include <mach/hardware.h>
40 
41 #include <mach/i2c.h>
42 
43 /* ----- global defines ----------------------------------------------- */
44 
45 #define DAVINCI_I2C_TIMEOUT	(1*HZ)
46 #define I2C_DAVINCI_INTR_ALL    (DAVINCI_I2C_IMR_AAS | \
47 				 DAVINCI_I2C_IMR_SCD | \
48 				 DAVINCI_I2C_IMR_ARDY | \
49 				 DAVINCI_I2C_IMR_NACK | \
50 				 DAVINCI_I2C_IMR_AL)
51 
52 #define DAVINCI_I2C_OAR_REG	0x00
53 #define DAVINCI_I2C_IMR_REG	0x04
54 #define DAVINCI_I2C_STR_REG	0x08
55 #define DAVINCI_I2C_CLKL_REG	0x0c
56 #define DAVINCI_I2C_CLKH_REG	0x10
57 #define DAVINCI_I2C_CNT_REG	0x14
58 #define DAVINCI_I2C_DRR_REG	0x18
59 #define DAVINCI_I2C_SAR_REG	0x1c
60 #define DAVINCI_I2C_DXR_REG	0x20
61 #define DAVINCI_I2C_MDR_REG	0x24
62 #define DAVINCI_I2C_IVR_REG	0x28
63 #define DAVINCI_I2C_EMDR_REG	0x2c
64 #define DAVINCI_I2C_PSC_REG	0x30
65 
66 #define DAVINCI_I2C_IVR_AAS	0x07
67 #define DAVINCI_I2C_IVR_SCD	0x06
68 #define DAVINCI_I2C_IVR_XRDY	0x05
69 #define DAVINCI_I2C_IVR_RDR	0x04
70 #define DAVINCI_I2C_IVR_ARDY	0x03
71 #define DAVINCI_I2C_IVR_NACK	0x02
72 #define DAVINCI_I2C_IVR_AL	0x01
73 
74 #define DAVINCI_I2C_STR_BB	(1 << 12)
75 #define DAVINCI_I2C_STR_RSFULL	(1 << 11)
76 #define DAVINCI_I2C_STR_SCD	(1 << 5)
77 #define DAVINCI_I2C_STR_ARDY	(1 << 2)
78 #define DAVINCI_I2C_STR_NACK	(1 << 1)
79 #define DAVINCI_I2C_STR_AL	(1 << 0)
80 
81 #define DAVINCI_I2C_MDR_NACK	(1 << 15)
82 #define DAVINCI_I2C_MDR_STT	(1 << 13)
83 #define DAVINCI_I2C_MDR_STP	(1 << 11)
84 #define DAVINCI_I2C_MDR_MST	(1 << 10)
85 #define DAVINCI_I2C_MDR_TRX	(1 << 9)
86 #define DAVINCI_I2C_MDR_XA	(1 << 8)
87 #define DAVINCI_I2C_MDR_RM	(1 << 7)
88 #define DAVINCI_I2C_MDR_IRS	(1 << 5)
89 
90 #define DAVINCI_I2C_IMR_AAS	(1 << 6)
91 #define DAVINCI_I2C_IMR_SCD	(1 << 5)
92 #define DAVINCI_I2C_IMR_XRDY	(1 << 4)
93 #define DAVINCI_I2C_IMR_RRDY	(1 << 3)
94 #define DAVINCI_I2C_IMR_ARDY	(1 << 2)
95 #define DAVINCI_I2C_IMR_NACK	(1 << 1)
96 #define DAVINCI_I2C_IMR_AL	(1 << 0)
97 
98 #define MOD_REG_BIT(val, mask, set) do { \
99 	if (set) { \
100 		val |= mask; \
101 	} else { \
102 		val &= ~mask; \
103 	} \
104 } while (0)
105 
106 struct davinci_i2c_dev {
107 	struct device           *dev;
108 	void __iomem		*base;
109 	struct completion	cmd_complete;
110 	struct clk              *clk;
111 	int			cmd_err;
112 	u8			*buf;
113 	size_t			buf_len;
114 	int			irq;
115 	u8			terminate;
116 	struct i2c_adapter	adapter;
117 };
118 
119 /* default platform data to use if not supplied in the platform_device */
120 static struct davinci_i2c_platform_data davinci_i2c_platform_data_default = {
121 	.bus_freq	= 100,
122 	.bus_delay	= 0,
123 };
124 
125 static inline void davinci_i2c_write_reg(struct davinci_i2c_dev *i2c_dev,
126 					 int reg, u16 val)
127 {
128 	__raw_writew(val, i2c_dev->base + reg);
129 }
130 
131 static inline u16 davinci_i2c_read_reg(struct davinci_i2c_dev *i2c_dev, int reg)
132 {
133 	return __raw_readw(i2c_dev->base + reg);
134 }
135 
136 /*
137  * This functions configures I2C and brings I2C out of reset.
138  * This function is called during I2C init function. This function
139  * also gets called if I2C encounters any errors.
140  */
141 static int i2c_davinci_init(struct davinci_i2c_dev *dev)
142 {
143 	struct davinci_i2c_platform_data *pdata = dev->dev->platform_data;
144 	u16 psc;
145 	u32 clk;
146 	u32 d;
147 	u32 clkh;
148 	u32 clkl;
149 	u32 input_clock = clk_get_rate(dev->clk);
150 	u16 w;
151 
152 	if (!pdata)
153 		pdata = &davinci_i2c_platform_data_default;
154 
155 	/* put I2C into reset */
156 	w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
157 	MOD_REG_BIT(w, DAVINCI_I2C_MDR_IRS, 0);
158 	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);
159 
160 	/* NOTE: I2C Clock divider programming info
161 	 * As per I2C specs the following formulas provide prescaler
162 	 * and low/high divider values
163 	 * input clk --> PSC Div -----------> ICCL/H Div --> output clock
164 	 *                       module clk
165 	 *
166 	 * output clk = module clk / (PSC + 1) [ (ICCL + d) + (ICCH + d) ]
167 	 *
168 	 * Thus,
169 	 * (ICCL + ICCH) = clk = (input clk / ((psc +1) * output clk)) - 2d;
170 	 *
171 	 * where if PSC == 0, d = 7,
172 	 *       if PSC == 1, d = 6
173 	 *       if PSC > 1 , d = 5
174 	 */
175 
176 	/* get minimum of 7 MHz clock, but max of 12 MHz */
177 	psc = (input_clock / 7000000) - 1;
178 	if ((input_clock / (psc + 1)) > 12000000)
179 		psc++;	/* better to run under spec than over */
180 	d = (psc >= 2) ? 5 : 7 - psc;
181 
182 	clk = ((input_clock / (psc + 1)) / (pdata->bus_freq * 1000)) - (d << 1);
183 	clkh = clk >> 1;
184 	clkl = clk - clkh;
185 
186 	davinci_i2c_write_reg(dev, DAVINCI_I2C_PSC_REG, psc);
187 	davinci_i2c_write_reg(dev, DAVINCI_I2C_CLKH_REG, clkh);
188 	davinci_i2c_write_reg(dev, DAVINCI_I2C_CLKL_REG, clkl);
189 
190 	dev_dbg(dev->dev, "input_clock = %d, CLK = %d\n", input_clock, clk);
191 	dev_dbg(dev->dev, "PSC  = %d\n",
192 		davinci_i2c_read_reg(dev, DAVINCI_I2C_PSC_REG));
193 	dev_dbg(dev->dev, "CLKL = %d\n",
194 		davinci_i2c_read_reg(dev, DAVINCI_I2C_CLKL_REG));
195 	dev_dbg(dev->dev, "CLKH = %d\n",
196 		davinci_i2c_read_reg(dev, DAVINCI_I2C_CLKH_REG));
197 	dev_dbg(dev->dev, "bus_freq = %dkHz, bus_delay = %d\n",
198 		pdata->bus_freq, pdata->bus_delay);
199 
200 	/* Take the I2C module out of reset: */
201 	w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
202 	MOD_REG_BIT(w, DAVINCI_I2C_MDR_IRS, 1);
203 	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);
204 
205 	/* Enable interrupts */
206 	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, I2C_DAVINCI_INTR_ALL);
207 
208 	return 0;
209 }
210 
211 /*
212  * Waiting for bus not busy
213  */
214 static int i2c_davinci_wait_bus_not_busy(struct davinci_i2c_dev *dev,
215 					 char allow_sleep)
216 {
217 	unsigned long timeout;
218 
219 	timeout = jiffies + DAVINCI_I2C_TIMEOUT;
220 	while (davinci_i2c_read_reg(dev, DAVINCI_I2C_STR_REG)
221 	       & DAVINCI_I2C_STR_BB) {
222 		if (time_after(jiffies, timeout)) {
223 			dev_warn(dev->dev,
224 				 "timeout waiting for bus ready\n");
225 			return -ETIMEDOUT;
226 		}
227 		if (allow_sleep)
228 			schedule_timeout(1);
229 	}
230 
231 	return 0;
232 }
233 
234 /*
235  * Low level master read/write transaction. This function is called
236  * from i2c_davinci_xfer.
237  */
238 static int
239 i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
240 {
241 	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
242 	struct davinci_i2c_platform_data *pdata = dev->dev->platform_data;
243 	u32 flag;
244 	u16 w;
245 	int r;
246 
247 	if (msg->len == 0)
248 		return -EINVAL;
249 
250 	if (!pdata)
251 		pdata = &davinci_i2c_platform_data_default;
252 	/* Introduce a delay, required for some boards (e.g Davinci EVM) */
253 	if (pdata->bus_delay)
254 		udelay(pdata->bus_delay);
255 
256 	/* set the slave address */
257 	davinci_i2c_write_reg(dev, DAVINCI_I2C_SAR_REG, msg->addr);
258 
259 	dev->buf = msg->buf;
260 	dev->buf_len = msg->len;
261 
262 	davinci_i2c_write_reg(dev, DAVINCI_I2C_CNT_REG, dev->buf_len);
263 
264 	INIT_COMPLETION(dev->cmd_complete);
265 	dev->cmd_err = 0;
266 
267 	/* Take I2C out of reset, configure it as master and set the
268 	 * start bit */
269 	flag = DAVINCI_I2C_MDR_IRS | DAVINCI_I2C_MDR_MST | DAVINCI_I2C_MDR_STT;
270 
271 	/* if the slave address is ten bit address, enable XA bit */
272 	if (msg->flags & I2C_M_TEN)
273 		flag |= DAVINCI_I2C_MDR_XA;
274 	if (!(msg->flags & I2C_M_RD))
275 		flag |= DAVINCI_I2C_MDR_TRX;
276 	if (stop)
277 		flag |= DAVINCI_I2C_MDR_STP;
278 
279 	/* Enable receive or transmit interrupts */
280 	w = davinci_i2c_read_reg(dev, DAVINCI_I2C_IMR_REG);
281 	if (msg->flags & I2C_M_RD)
282 		MOD_REG_BIT(w, DAVINCI_I2C_IMR_RRDY, 1);
283 	else
284 		MOD_REG_BIT(w, DAVINCI_I2C_IMR_XRDY, 1);
285 	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, w);
286 
287 	dev->terminate = 0;
288 	/* write the data into mode register */
289 	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
290 
291 	r = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
292 						      DAVINCI_I2C_TIMEOUT);
293 	if (r == 0) {
294 		dev_err(dev->dev, "controller timed out\n");
295 		i2c_davinci_init(dev);
296 		dev->buf_len = 0;
297 		return -ETIMEDOUT;
298 	}
299 	if (dev->buf_len) {
300 		/* This should be 0 if all bytes were transferred
301 		 * or dev->cmd_err denotes an error.
302 		 * A signal may have aborted the transfer.
303 		 */
304 		if (r >= 0) {
305 			dev_err(dev->dev, "abnormal termination buf_len=%i\n",
306 				dev->buf_len);
307 			r = -EREMOTEIO;
308 		}
309 		dev->terminate = 1;
310 		wmb();
311 		dev->buf_len = 0;
312 	}
313 	if (r < 0)
314 		return r;
315 
316 	/* no error */
317 	if (likely(!dev->cmd_err))
318 		return msg->len;
319 
320 	/* We have an error */
321 	if (dev->cmd_err & DAVINCI_I2C_STR_AL) {
322 		i2c_davinci_init(dev);
323 		return -EIO;
324 	}
325 
326 	if (dev->cmd_err & DAVINCI_I2C_STR_NACK) {
327 		if (msg->flags & I2C_M_IGNORE_NAK)
328 			return msg->len;
329 		if (stop) {
330 			w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
331 			MOD_REG_BIT(w, DAVINCI_I2C_MDR_STP, 1);
332 			davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);
333 		}
334 		return -EREMOTEIO;
335 	}
336 	return -EIO;
337 }
338 
339 /*
340  * Prepare controller for a transaction and call i2c_davinci_xfer_msg
341  */
342 static int
343 i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
344 {
345 	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
346 	int i;
347 	int ret;
348 
349 	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
350 
351 	ret = i2c_davinci_wait_bus_not_busy(dev, 1);
352 	if (ret < 0) {
353 		dev_warn(dev->dev, "timeout waiting for bus ready\n");
354 		return ret;
355 	}
356 
357 	for (i = 0; i < num; i++) {
358 		ret = i2c_davinci_xfer_msg(adap, &msgs[i], (i == (num - 1)));
359 		dev_dbg(dev->dev, "%s [%d/%d] ret: %d\n", __func__, i + 1, num,
360 			ret);
361 		if (ret < 0)
362 			return ret;
363 	}
364 	return num;
365 }
366 
367 static u32 i2c_davinci_func(struct i2c_adapter *adap)
368 {
369 	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
370 }
371 
372 static void terminate_read(struct davinci_i2c_dev *dev)
373 {
374 	u16 w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
375 	w |= DAVINCI_I2C_MDR_NACK;
376 	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);
377 
378 	/* Throw away data */
379 	davinci_i2c_read_reg(dev, DAVINCI_I2C_DRR_REG);
380 	if (!dev->terminate)
381 		dev_err(dev->dev, "RDR IRQ while no data requested\n");
382 }
383 static void terminate_write(struct davinci_i2c_dev *dev)
384 {
385 	u16 w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
386 	w |= DAVINCI_I2C_MDR_RM | DAVINCI_I2C_MDR_STP;
387 	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);
388 
389 	if (!dev->terminate)
390 		dev_err(dev->dev, "TDR IRQ while no data to send\n");
391 }
392 
393 /*
394  * Interrupt service routine. This gets called whenever an I2C interrupt
395  * occurs.
396  */
397 static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id)
398 {
399 	struct davinci_i2c_dev *dev = dev_id;
400 	u32 stat;
401 	int count = 0;
402 	u16 w;
403 
404 	while ((stat = davinci_i2c_read_reg(dev, DAVINCI_I2C_IVR_REG))) {
405 		dev_dbg(dev->dev, "%s: stat=0x%x\n", __func__, stat);
406 		if (count++ == 100) {
407 			dev_warn(dev->dev, "Too much work in one IRQ\n");
408 			break;
409 		}
410 
411 		switch (stat) {
412 		case DAVINCI_I2C_IVR_AL:
413 			/* Arbitration lost, must retry */
414 			dev->cmd_err |= DAVINCI_I2C_STR_AL;
415 			dev->buf_len = 0;
416 			complete(&dev->cmd_complete);
417 			break;
418 
419 		case DAVINCI_I2C_IVR_NACK:
420 			dev->cmd_err |= DAVINCI_I2C_STR_NACK;
421 			dev->buf_len = 0;
422 			complete(&dev->cmd_complete);
423 			break;
424 
425 		case DAVINCI_I2C_IVR_ARDY:
426 			davinci_i2c_write_reg(dev,
427 				DAVINCI_I2C_STR_REG, DAVINCI_I2C_STR_ARDY);
428 			complete(&dev->cmd_complete);
429 			break;
430 
431 		case DAVINCI_I2C_IVR_RDR:
432 			if (dev->buf_len) {
433 				*dev->buf++ =
434 				    davinci_i2c_read_reg(dev,
435 							 DAVINCI_I2C_DRR_REG);
436 				dev->buf_len--;
437 				if (dev->buf_len)
438 					continue;
439 
440 				davinci_i2c_write_reg(dev,
441 					DAVINCI_I2C_STR_REG,
442 					DAVINCI_I2C_IMR_RRDY);
443 			} else {
444 				/* signal can terminate transfer */
445 				terminate_read(dev);
446 			}
447 			break;
448 
449 		case DAVINCI_I2C_IVR_XRDY:
450 			if (dev->buf_len) {
451 				davinci_i2c_write_reg(dev, DAVINCI_I2C_DXR_REG,
452 						      *dev->buf++);
453 				dev->buf_len--;
454 				if (dev->buf_len)
455 					continue;
456 
457 				w = davinci_i2c_read_reg(dev,
458 							 DAVINCI_I2C_IMR_REG);
459 				MOD_REG_BIT(w, DAVINCI_I2C_IMR_XRDY, 0);
460 				davinci_i2c_write_reg(dev,
461 						      DAVINCI_I2C_IMR_REG,
462 						      w);
463 			} else {
464 				/* signal can terminate transfer */
465 				terminate_write(dev);
466 			}
467 			break;
468 
469 		case DAVINCI_I2C_IVR_SCD:
470 			davinci_i2c_write_reg(dev,
471 				DAVINCI_I2C_STR_REG, DAVINCI_I2C_STR_SCD);
472 			complete(&dev->cmd_complete);
473 			break;
474 
475 		case DAVINCI_I2C_IVR_AAS:
476 			dev_warn(dev->dev, "Address as slave interrupt\n");
477 		}/* switch */
478 	}/* while */
479 
480 	return count ? IRQ_HANDLED : IRQ_NONE;
481 }
482 
483 static struct i2c_algorithm i2c_davinci_algo = {
484 	.master_xfer	= i2c_davinci_xfer,
485 	.functionality	= i2c_davinci_func,
486 };
487 
488 static int davinci_i2c_probe(struct platform_device *pdev)
489 {
490 	struct davinci_i2c_dev *dev;
491 	struct i2c_adapter *adap;
492 	struct resource *mem, *irq, *ioarea;
493 	int r;
494 
495 	/* NOTE: driver uses the static register mapping */
496 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
497 	if (!mem) {
498 		dev_err(&pdev->dev, "no mem resource?\n");
499 		return -ENODEV;
500 	}
501 
502 	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
503 	if (!irq) {
504 		dev_err(&pdev->dev, "no irq resource?\n");
505 		return -ENODEV;
506 	}
507 
508 	ioarea = request_mem_region(mem->start, (mem->end - mem->start) + 1,
509 				    pdev->name);
510 	if (!ioarea) {
511 		dev_err(&pdev->dev, "I2C region already claimed\n");
512 		return -EBUSY;
513 	}
514 
515 	dev = kzalloc(sizeof(struct davinci_i2c_dev), GFP_KERNEL);
516 	if (!dev) {
517 		r = -ENOMEM;
518 		goto err_release_region;
519 	}
520 
521 	init_completion(&dev->cmd_complete);
522 	dev->dev = get_device(&pdev->dev);
523 	dev->irq = irq->start;
524 	platform_set_drvdata(pdev, dev);
525 
526 	dev->clk = clk_get(&pdev->dev, "I2CCLK");
527 	if (IS_ERR(dev->clk)) {
528 		r = -ENODEV;
529 		goto err_free_mem;
530 	}
531 	clk_enable(dev->clk);
532 
533 	dev->base = (void __iomem *)IO_ADDRESS(mem->start);
534 	i2c_davinci_init(dev);
535 
536 	r = request_irq(dev->irq, i2c_davinci_isr, 0, pdev->name, dev);
537 	if (r) {
538 		dev_err(&pdev->dev, "failure requesting irq %i\n", dev->irq);
539 		goto err_unuse_clocks;
540 	}
541 
542 	adap = &dev->adapter;
543 	i2c_set_adapdata(adap, dev);
544 	adap->owner = THIS_MODULE;
545 	adap->class = I2C_CLASS_HWMON;
546 	strlcpy(adap->name, "DaVinci I2C adapter", sizeof(adap->name));
547 	adap->algo = &i2c_davinci_algo;
548 	adap->dev.parent = &pdev->dev;
549 
550 	/* FIXME */
551 	adap->timeout = 1;
552 
553 	adap->nr = pdev->id;
554 	r = i2c_add_numbered_adapter(adap);
555 	if (r) {
556 		dev_err(&pdev->dev, "failure adding adapter\n");
557 		goto err_free_irq;
558 	}
559 
560 	return 0;
561 
562 err_free_irq:
563 	free_irq(dev->irq, dev);
564 err_unuse_clocks:
565 	clk_disable(dev->clk);
566 	clk_put(dev->clk);
567 	dev->clk = NULL;
568 err_free_mem:
569 	platform_set_drvdata(pdev, NULL);
570 	put_device(&pdev->dev);
571 	kfree(dev);
572 err_release_region:
573 	release_mem_region(mem->start, (mem->end - mem->start) + 1);
574 
575 	return r;
576 }
577 
578 static int davinci_i2c_remove(struct platform_device *pdev)
579 {
580 	struct davinci_i2c_dev *dev = platform_get_drvdata(pdev);
581 	struct resource *mem;
582 
583 	platform_set_drvdata(pdev, NULL);
584 	i2c_del_adapter(&dev->adapter);
585 	put_device(&pdev->dev);
586 
587 	clk_disable(dev->clk);
588 	clk_put(dev->clk);
589 	dev->clk = NULL;
590 
591 	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, 0);
592 	free_irq(IRQ_I2C, dev);
593 	kfree(dev);
594 
595 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
596 	release_mem_region(mem->start, (mem->end - mem->start) + 1);
597 	return 0;
598 }
599 
600 /* work with hotplug and coldplug */
601 MODULE_ALIAS("platform:i2c_davinci");
602 
603 static struct platform_driver davinci_i2c_driver = {
604 	.probe		= davinci_i2c_probe,
605 	.remove		= davinci_i2c_remove,
606 	.driver		= {
607 		.name	= "i2c_davinci",
608 		.owner	= THIS_MODULE,
609 	},
610 };
611 
612 /* I2C may be needed to bring up other drivers */
613 static int __init davinci_i2c_init_driver(void)
614 {
615 	return platform_driver_register(&davinci_i2c_driver);
616 }
617 subsys_initcall(davinci_i2c_init_driver);
618 
619 static void __exit davinci_i2c_exit_driver(void)
620 {
621 	platform_driver_unregister(&davinci_i2c_driver);
622 }
623 module_exit(davinci_i2c_exit_driver);
624 
625 MODULE_AUTHOR("Texas Instruments India");
626 MODULE_DESCRIPTION("TI DaVinci I2C bus adapter");
627 MODULE_LICENSE("GPL");
628