summaryrefslogtreecommitdiff
path: root/drivers/i2c/busses/i2c-mxs.c
blob: 7e78f7c87857c7f0d7af5417064f19e822b4a5f4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
/*
 * Freescale MXS I2C bus driver
 *
 * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
 *
 * based on a (non-working) driver which was:
 *
 * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
 *
 * TODO: add dma-support if platform-support for it is available
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */

#include <linux/slab.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/platform_device.h>
#include <linux/jiffies.h>
#include <linux/io.h>

#include <mach/common.h>

#define DRIVER_NAME "mxs-i2c"

#define MXS_I2C_CTRL0		(0x00)
#define MXS_I2C_CTRL0_SET	(0x04)

#define MXS_I2C_CTRL0_SFTRST			0x80000000
#define MXS_I2C_CTRL0_SEND_NAK_ON_LAST		0x02000000
#define MXS_I2C_CTRL0_RETAIN_CLOCK		0x00200000
#define MXS_I2C_CTRL0_POST_SEND_STOP		0x00100000
#define MXS_I2C_CTRL0_PRE_SEND_START		0x00080000
#define MXS_I2C_CTRL0_MASTER_MODE		0x00020000
#define MXS_I2C_CTRL0_DIRECTION			0x00010000
#define MXS_I2C_CTRL0_XFER_COUNT(v)		((v) & 0x0000FFFF)

#define MXS_I2C_CTRL1		(0x40)
#define MXS_I2C_CTRL1_SET	(0x44)
#define MXS_I2C_CTRL1_CLR	(0x48)

#define MXS_I2C_CTRL1_BUS_FREE_IRQ		0x80
#define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ	0x40
#define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ		0x20
#define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ	0x10
#define MXS_I2C_CTRL1_EARLY_TERM_IRQ		0x08
#define MXS_I2C_CTRL1_MASTER_LOSS_IRQ		0x04
#define MXS_I2C_CTRL1_SLAVE_STOP_IRQ		0x02
#define MXS_I2C_CTRL1_SLAVE_IRQ			0x01

#define MXS_I2C_IRQ_MASK	(MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
				 MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
				 MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
				 MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
				 MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
				 MXS_I2C_CTRL1_SLAVE_IRQ)

#define MXS_I2C_QUEUECTRL	(0x60)
#define MXS_I2C_QUEUECTRL_SET	(0x64)
#define MXS_I2C_QUEUECTRL_CLR	(0x68)

#define MXS_I2C_QUEUECTRL_QUEUE_RUN		0x20
#define MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE	0x04

#define MXS_I2C_QUEUESTAT	(0x70)
#define MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY        0x00002000

#define MXS_I2C_QUEUECMD	(0x80)

#define MXS_I2C_QUEUEDATA	(0x90)

#define MXS_I2C_DATA		(0xa0)


#define MXS_CMD_I2C_SELECT	(MXS_I2C_CTRL0_RETAIN_CLOCK |	\
				 MXS_I2C_CTRL0_PRE_SEND_START |	\
				 MXS_I2C_CTRL0_MASTER_MODE |	\
				 MXS_I2C_CTRL0_DIRECTION |	\
				 MXS_I2C_CTRL0_XFER_COUNT(1))

#define MXS_CMD_I2C_WRITE	(MXS_I2C_CTRL0_PRE_SEND_START |	\
				 MXS_I2C_CTRL0_MASTER_MODE |	\
				 MXS_I2C_CTRL0_DIRECTION)

#define MXS_CMD_I2C_READ	(MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
				 MXS_I2C_CTRL0_MASTER_MODE)

/**
 * struct mxs_i2c_dev - per device, private MXS-I2C data
 *
 * @dev: driver model device node
 * @regs: IO registers pointer
 * @cmd_complete: completion object for transaction wait
 * @cmd_err: error code for last transaction
 * @adapter: i2c subsystem adapter node
 */
struct mxs_i2c_dev {
	struct device *dev;
	void __iomem *regs;
	struct completion cmd_complete;
	u32 cmd_err;
	struct i2c_adapter adapter;
};

/*
 * TODO: check if calls to here are really needed. If not, we could get rid of
 * mxs_reset_block and the mach-dependency. Needs an I2C analyzer, probably.
 */
static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
{
	mxs_reset_block(i2c->regs);
	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
	writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
			i2c->regs + MXS_I2C_QUEUECTRL_SET);
}

static void mxs_i2c_pioq_setup_read(struct mxs_i2c_dev *i2c, u8 addr, int len,
					int flags)
{
	u32 data;

	writel(MXS_CMD_I2C_SELECT, i2c->regs + MXS_I2C_QUEUECMD);

	data = (addr << 1) | I2C_SMBUS_READ;
	writel(data, i2c->regs + MXS_I2C_DATA);

	data = MXS_CMD_I2C_READ | MXS_I2C_CTRL0_XFER_COUNT(len) | flags;
	writel(data, i2c->regs + MXS_I2C_QUEUECMD);
}

static void mxs_i2c_pioq_setup_write(struct mxs_i2c_dev *i2c,
				    u8 addr, u8 *buf, int len, int flags)
{
	u32 data;
	int i, shifts_left;

	data = MXS_CMD_I2C_WRITE | MXS_I2C_CTRL0_XFER_COUNT(len + 1) | flags;
	writel(data, i2c->regs + MXS_I2C_QUEUECMD);

	/*
	 * We have to copy the slave address (u8) and buffer (arbitrary number
	 * of u8) into the data register (u32). To achieve that, the u8 are put
	 * into the MSBs of 'data' which is then shifted for the next u8. When
	 * appropriate, 'data' is written to MXS_I2C_DATA. So, the first u32
	 * looks like this:
	 *
	 *  3          2          1          0
	 * 10987654|32109876|54321098|76543210
	 * --------+--------+--------+--------
	 * buffer+2|buffer+1|buffer+0|slave_addr
	 */

	data = ((addr << 1) | I2C_SMBUS_WRITE) << 24;

	for (i = 0; i < len; i++) {
		data >>= 8;
		data |= buf[i] << 24;
		if ((i & 3) == 2)
			writel(data, i2c->regs + MXS_I2C_DATA);
	}

	/* Write out the remaining bytes if any */
	shifts_left = 24 - (i & 3) * 8;
	if (shifts_left)
		writel(data >> shifts_left, i2c->regs + MXS_I2C_DATA);
}

/*
 * TODO: should be replaceable with a waitqueue and RD_QUEUE_IRQ (setting the
 * rd_threshold to 1). Couldn't get this to work, though.
 */
static int mxs_i2c_wait_for_data(struct mxs_i2c_dev *i2c)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(1000);

	while (readl(i2c->regs + MXS_I2C_QUEUESTAT)
			& MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY) {
			if (time_after(jiffies, timeout))
				return -ETIMEDOUT;
			cond_resched();
	}

	return 0;
}

static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
{
	u32 data;
	int i;

	for (i = 0; i < len; i++) {
		if ((i & 3) == 0) {
			if (mxs_i2c_wait_for_data(i2c))
				return -ETIMEDOUT;
			data = readl(i2c->regs + MXS_I2C_QUEUEDATA);
		}
		buf[i] = data & 0xff;
		data >>= 8;
	}

	return 0;
}

/*
 * Low level master read/write transaction.
 */
static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
				int stop)
{
	struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
	int ret;
	int flags;

	init_completion(&i2c->cmd_complete);

	dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
		msg->addr, msg->len, msg->flags, stop);

	if (msg->len == 0)
		return -EINVAL;

	flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;

	if (msg->flags & I2C_M_RD)
		mxs_i2c_pioq_setup_read(i2c, msg->addr, msg->len, flags);
	else
		mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf, msg->len,
					flags);

	writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
			i2c->regs + MXS_I2C_QUEUECTRL_SET);

	ret = wait_for_completion_timeout(&i2c->cmd_complete,
						msecs_to_jiffies(1000));
	if (ret == 0)
		goto timeout;

	if ((!i2c->cmd_err) && (msg->flags & I2C_M_RD)) {
		ret = mxs_i2c_finish_read(i2c, msg->buf, msg->len);
		if (ret)
			goto timeout;
	}

	if (i2c->cmd_err == -ENXIO)
		mxs_i2c_reset(i2c);

	dev_dbg(i2c->dev, "Done with err=%d\n", i2c->cmd_err);

	return i2c->cmd_err;

timeout:
	dev_dbg(i2c->dev, "Timeout!\n");
	mxs_i2c_reset(i2c);
	return -ETIMEDOUT;
}

static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
			int num)
{
	int i;
	int err;

	for (i = 0; i < num; i++) {
		err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
		if (err)
			return err;
	}

	return num;
}

static u32 mxs_i2c_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
}

static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
{
	struct mxs_i2c_dev *i2c = dev_id;
	u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;

	if (!stat)
		return IRQ_NONE;

	if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
		i2c->cmd_err = -ENXIO;
	else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
		    MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
		    MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
		/* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
		i2c->cmd_err = -EIO;
	else
		i2c->cmd_err = 0;

	complete(&i2c->cmd_complete);

	writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
	return IRQ_HANDLED;
}

static const struct i2c_algorithm mxs_i2c_algo = {
	.master_xfer = mxs_i2c_xfer,
	.functionality = mxs_i2c_func,
};

static int __devinit mxs_i2c_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct mxs_i2c_dev *i2c;
	struct i2c_adapter *adap;
	struct resource *res;
	resource_size_t res_size;
	int err, irq;

	i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
	if (!i2c)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res)
		return -ENOENT;

	res_size = resource_size(res);
	if (!devm_request_mem_region(dev, res->start, res_size, res->name))
		return -EBUSY;

	i2c->regs = devm_ioremap_nocache(dev, res->start, res_size);
	if (!i2c->regs)
		return -EBUSY;

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return irq;

	err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
	if (err)
		return err;

	i2c->dev = dev;
	platform_set_drvdata(pdev, i2c);

	/* Do reset to enforce correct startup after pinmuxing */
	mxs_i2c_reset(i2c);

	adap = &i2c->adapter;
	strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
	adap->owner = THIS_MODULE;
	adap->algo = &mxs_i2c_algo;
	adap->dev.parent = dev;
	adap->nr = pdev->id;
	i2c_set_adapdata(adap, i2c);
	err = i2c_add_numbered_adapter(adap);
	if (err) {
		dev_err(dev, "Failed to add adapter (%d)\n", err);
		writel(MXS_I2C_CTRL0_SFTRST,
				i2c->regs + MXS_I2C_CTRL0_SET);
		return err;
	}

	return 0;
}

static int __devexit mxs_i2c_remove(struct platform_device *pdev)
{
	struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
	int ret;

	ret = i2c_del_adapter(&i2c->adapter);
	if (ret)
		return -EBUSY;

	writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
			i2c->regs + MXS_I2C_QUEUECTRL_CLR);
	writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);

	platform_set_drvdata(pdev, NULL);

	return 0;
}

static struct platform_driver mxs_i2c_driver = {
	.driver = {
		   .name = DRIVER_NAME,
		   .owner = THIS_MODULE,
		   },
	.remove = __devexit_p(mxs_i2c_remove),
};

static int __init mxs_i2c_init(void)
{
	return platform_driver_probe(&mxs_i2c_driver, mxs_i2c_probe);
}
subsys_initcall(mxs_i2c_init);

static void __exit mxs_i2c_exit(void)
{
	platform_driver_unregister(&mxs_i2c_driver);
}
module_exit(mxs_i2c_exit);

MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
MODULE_DESCRIPTION("MXS I2C Bus Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRIVER_NAME);