summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/busses/i2c-kempld.c
blob: 1c874aaa0447ac891754a69a4cf5539f6ecae113 (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
/*
 * I2C bus driver for Kontron COM modules
 *
 * Copyright (c) 2010-2013 Kontron Europe GmbH
 * Author: Michael Brunner <michael.brunner@kontron.com>
 *
 * The driver is based on the i2c-ocores driver by Peter Korsgaard.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/mfd/kempld.h>

#define KEMPLD_I2C_PRELOW	0x0b
#define KEMPLD_I2C_PREHIGH	0x0c
#define KEMPLD_I2C_DATA		0x0e

#define KEMPLD_I2C_CTRL		0x0d
#define I2C_CTRL_IEN		0x40
#define I2C_CTRL_EN		0x80

#define KEMPLD_I2C_STAT		0x0f
#define I2C_STAT_IF		0x01
#define I2C_STAT_TIP		0x02
#define I2C_STAT_ARBLOST	0x20
#define I2C_STAT_BUSY		0x40
#define I2C_STAT_NACK		0x80

#define KEMPLD_I2C_CMD		0x0f
#define I2C_CMD_START		0x91
#define I2C_CMD_STOP		0x41
#define I2C_CMD_READ		0x21
#define I2C_CMD_WRITE		0x11
#define I2C_CMD_READ_ACK	0x21
#define I2C_CMD_READ_NACK	0x29
#define I2C_CMD_IACK		0x01

#define KEMPLD_I2C_FREQ_MAX	2700	/* 2.7 mHz */
#define KEMPLD_I2C_FREQ_STD	100	/* 100 kHz */

enum {
	STATE_DONE = 0,
	STATE_INIT,
	STATE_ADDR,
	STATE_ADDR10,
	STATE_START,
	STATE_WRITE,
	STATE_READ,
	STATE_ERROR,
};

struct kempld_i2c_data {
	struct device			*dev;
	struct kempld_device_data	*pld;
	struct i2c_adapter		adap;
	struct i2c_msg			*msg;
	int				pos;
	int				nmsgs;
	int				state;
	bool				was_active;
};

static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
module_param(bus_frequency, uint, 0);
MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
				__MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");

static int i2c_bus = -1;
module_param(i2c_bus, int, 0);
MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");

static bool i2c_gpio_mux;
module_param(i2c_gpio_mux, bool, 0);
MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");

/*
 * kempld_get_mutex must be called prior to calling this function.
 */
static int kempld_i2c_process(struct kempld_i2c_data *i2c)
{
	struct kempld_device_data *pld = i2c->pld;
	u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
	struct i2c_msg *msg = i2c->msg;
	u8 addr;

	/* Ready? */
	if (stat & I2C_STAT_TIP)
		return -EBUSY;

	if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
		/* Stop has been sent */
		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
		if (i2c->state == STATE_ERROR)
			return -EIO;
		return 0;
	}

	/* Error? */
	if (stat & I2C_STAT_ARBLOST) {
		i2c->state = STATE_ERROR;
		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
		return -EAGAIN;
	}

	if (i2c->state == STATE_INIT) {
		if (stat & I2C_STAT_BUSY)
			return -EBUSY;

		i2c->state = STATE_ADDR;
	}

	if (i2c->state == STATE_ADDR) {
		/* 10 bit address? */
		if (i2c->msg->flags & I2C_M_TEN) {
			addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
			/* Set read bit if necessary */
			addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
			i2c->state = STATE_ADDR10;
		} else {
			addr = i2c_8bit_addr_from_msg(i2c->msg);
			i2c->state = STATE_START;
		}

		kempld_write8(pld, KEMPLD_I2C_DATA, addr);
		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);

		return 0;
	}

	/* Second part of 10 bit addressing */
	if (i2c->state == STATE_ADDR10) {
		kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);

		i2c->state = STATE_START;
		return 0;
	}

	if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
		i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;

		if (stat & I2C_STAT_NACK) {
			i2c->state = STATE_ERROR;
			kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
			return -ENXIO;
		}
	} else {
		msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
	}

	if (i2c->pos >= msg->len) {
		i2c->nmsgs--;
		i2c->msg++;
		i2c->pos = 0;
		msg = i2c->msg;

		if (i2c->nmsgs) {
			if (!(msg->flags & I2C_M_NOSTART)) {
				i2c->state = STATE_ADDR;
				return 0;
			} else {
				i2c->state = (msg->flags & I2C_M_RD)
					? STATE_READ : STATE_WRITE;
			}
		} else {
			i2c->state = STATE_DONE;
			kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
			return 0;
		}
	}

	if (i2c->state == STATE_READ) {
		kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
			      I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
	} else {
		kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
	}

	return 0;
}

static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
				int num)
{
	struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
	struct kempld_device_data *pld = i2c->pld;
	unsigned long timeout = jiffies + HZ;
	int ret;

	i2c->msg = msgs;
	i2c->pos = 0;
	i2c->nmsgs = num;
	i2c->state = STATE_INIT;

	/* Handle the transfer */
	while (time_before(jiffies, timeout)) {
		kempld_get_mutex(pld);
		ret = kempld_i2c_process(i2c);
		kempld_release_mutex(pld);

		if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
			return (i2c->state == STATE_DONE) ? num : ret;

		if (ret == 0)
			timeout = jiffies + HZ;

		usleep_range(5, 15);
	}

	i2c->state = STATE_ERROR;

	return -ETIMEDOUT;
}

/*
 * kempld_get_mutex must be called prior to calling this function.
 */
static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
{
	struct kempld_device_data *pld = i2c->pld;
	u16 prescale_corr;
	long prescale;
	u8 ctrl;
	u8 stat;
	u8 cfg;

	/* Make sure the device is disabled */
	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
	ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

	if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
		bus_frequency = KEMPLD_I2C_FREQ_MAX;

	if (pld->info.spec_major == 1)
		prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
	else
		prescale = pld->pld_clock / (bus_frequency * 4) - 3000;

	if (prescale < 0)
		prescale = 0;

	/* Round to the best matching value */
	prescale_corr = prescale / 1000;
	if (prescale % 1000 >= 500)
		prescale_corr++;

	kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
	kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);

	/* Activate I2C bus output on GPIO pins */
	cfg = kempld_read8(pld, KEMPLD_CFG);
	if (i2c_gpio_mux)
		cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
	else
		cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
	kempld_write8(pld, KEMPLD_CFG, cfg);

	/* Enable the device */
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
	ctrl |= I2C_CTRL_EN;
	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

	stat = kempld_read8(pld, KEMPLD_I2C_STAT);
	if (stat & I2C_STAT_BUSY)
		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
}

static u32 kempld_i2c_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm kempld_i2c_algorithm = {
	.master_xfer	= kempld_i2c_xfer,
	.functionality	= kempld_i2c_func,
};

static const struct i2c_adapter kempld_i2c_adapter = {
	.owner		= THIS_MODULE,
	.name		= "i2c-kempld",
	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
	.algo		= &kempld_i2c_algorithm,
};

static int kempld_i2c_probe(struct platform_device *pdev)
{
	struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
	struct kempld_i2c_data *i2c;
	int ret;
	u8 ctrl;

	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
	if (!i2c)
		return -ENOMEM;

	i2c->pld = pld;
	i2c->dev = &pdev->dev;
	i2c->adap = kempld_i2c_adapter;
	i2c->adap.dev.parent = i2c->dev;
	i2c_set_adapdata(&i2c->adap, i2c);
	platform_set_drvdata(pdev, i2c);

	kempld_get_mutex(pld);
	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);

	if (ctrl & I2C_CTRL_EN)
		i2c->was_active = true;

	kempld_i2c_device_init(i2c);
	kempld_release_mutex(pld);

	/* Add I2C adapter to I2C tree */
	if (i2c_bus >= -1)
		i2c->adap.nr = i2c_bus;
	ret = i2c_add_numbered_adapter(&i2c->adap);
	if (ret)
		return ret;

	dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
		 bus_frequency);

	return 0;
}

static int kempld_i2c_remove(struct platform_device *pdev)
{
	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
	struct kempld_device_data *pld = i2c->pld;
	u8 ctrl;

	kempld_get_mutex(pld);
	/*
	 * Disable I2C logic if it was not activated before the
	 * driver loaded
	 */
	if (!i2c->was_active) {
		ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
		ctrl &= ~I2C_CTRL_EN;
		kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
	}
	kempld_release_mutex(pld);

	i2c_del_adapter(&i2c->adap);

	return 0;
}

#ifdef CONFIG_PM
static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
{
	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
	struct kempld_device_data *pld = i2c->pld;
	u8 ctrl;

	kempld_get_mutex(pld);
	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
	ctrl &= ~I2C_CTRL_EN;
	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
	kempld_release_mutex(pld);

	return 0;
}

static int kempld_i2c_resume(struct platform_device *pdev)
{
	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
	struct kempld_device_data *pld = i2c->pld;

	kempld_get_mutex(pld);
	kempld_i2c_device_init(i2c);
	kempld_release_mutex(pld);

	return 0;
}
#else
#define kempld_i2c_suspend	NULL
#define kempld_i2c_resume	NULL
#endif

static struct platform_driver kempld_i2c_driver = {
	.driver = {
		.name = "kempld-i2c",
	},
	.probe		= kempld_i2c_probe,
	.remove		= kempld_i2c_remove,
	.suspend	= kempld_i2c_suspend,
	.resume		= kempld_i2c_resume,
};

module_platform_driver(kempld_i2c_driver);

MODULE_DESCRIPTION("KEM PLD I2C Driver");
MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:kempld_i2c");