aboutsummaryrefslogtreecommitdiff
path: root/drivers/i2c/chips/ds1337.c
blob: a9d4ac770e398b4c130e044eb25a21d930e17d5e (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
/*
 *  linux/drivers/i2c/chips/ds1337.c
 *
 *  Copyright (C) 2005 James Chapman <jchapman@katalix.com>
 *
 *	based on linux/drivers/acorn/char/pcf8583.c
 *  Copyright (C) 2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Driver for Dallas Semiconductor DS1337 and DS1339 real time clock chip
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/string.h>
#include <linux/rtc.h>		/* get the user-level API */
#include <linux/bcd.h>
#include <linux/list.h>

/* Device registers */
#define DS1337_REG_HOUR		2
#define DS1337_REG_DAY		3
#define DS1337_REG_DATE		4
#define DS1337_REG_MONTH	5
#define DS1337_REG_CONTROL	14
#define DS1337_REG_STATUS	15

/* FIXME - how do we export these interface constants? */
#define DS1337_GET_DATE		0
#define DS1337_SET_DATE		1

/*
 * Functions declaration
 */
static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };

I2C_CLIENT_INSMOD_1(ds1337);

static int ds1337_attach_adapter(struct i2c_adapter *adapter);
static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
static void ds1337_init_client(struct i2c_client *client);
static int ds1337_detach_client(struct i2c_client *client);
static int ds1337_command(struct i2c_client *client, unsigned int cmd,
			  void *arg);

/*
 * Driver data (common to all clients)
 */
static struct i2c_driver ds1337_driver = {
	.driver = {
		.owner	= THIS_MODULE,
		.name	= "ds1337",
	},
	.attach_adapter	= ds1337_attach_adapter,
	.detach_client	= ds1337_detach_client,
	.command	= ds1337_command,
};

/*
 * Client data (each client gets its own)
 */
struct ds1337_data {
	struct i2c_client client;
	struct list_head list;
};

/*
 * Internal variables
 */
static LIST_HEAD(ds1337_clients);

static inline int ds1337_read(struct i2c_client *client, u8 reg, u8 *value)
{
	s32 tmp = i2c_smbus_read_byte_data(client, reg);

	if (tmp < 0)
		return -EIO;

	*value = tmp;

	return 0;
}

/*
 * Chip access functions
 */
static int ds1337_get_datetime(struct i2c_client *client, struct rtc_time *dt)
{
	int result;
	u8 buf[7];
	u8 val;
	struct i2c_msg msg[2];
	u8 offs = 0;

	if (!dt) {
		dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
		return -EINVAL;
	}

	msg[0].addr = client->addr;
	msg[0].flags = 0;
	msg[0].len = 1;
	msg[0].buf = &offs;

	msg[1].addr = client->addr;
	msg[1].flags = I2C_M_RD;
	msg[1].len = sizeof(buf);
	msg[1].buf = &buf[0];

	result = i2c_transfer(client->adapter, msg, 2);

	dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
		__FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
		buf[4], buf[5], buf[6]);

	if (result == 2) {
		dt->tm_sec = BCD2BIN(buf[0]);
		dt->tm_min = BCD2BIN(buf[1]);
		val = buf[2] & 0x3f;
		dt->tm_hour = BCD2BIN(val);
		dt->tm_wday = BCD2BIN(buf[3]) - 1;
		dt->tm_mday = BCD2BIN(buf[4]);
		val = buf[5] & 0x7f;
		dt->tm_mon = BCD2BIN(val) - 1;
		dt->tm_year = BCD2BIN(buf[6]);
		if (buf[5] & 0x80)
			dt->tm_year += 100;

		dev_dbg(&client->dev, "%s: secs=%d, mins=%d, "
			"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
			__FUNCTION__, dt->tm_sec, dt->tm_min,
			dt->tm_hour, dt->tm_mday,
			dt->tm_mon, dt->tm_year, dt->tm_wday);

		return 0;
	}

	dev_err(&client->dev, "error reading data! %d\n", result);
	return -EIO;
}

static int ds1337_set_datetime(struct i2c_client *client, struct rtc_time *dt)
{
	int result;
	u8 buf[8];
	u8 val;
	struct i2c_msg msg[1];

	if (!dt) {
		dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
		return -EINVAL;
	}

	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
		"mday=%d, mon=%d, year=%d, wday=%d\n", __FUNCTION__,
		dt->tm_sec, dt->tm_min, dt->tm_hour,
		dt->tm_mday, dt->tm_mon, dt->tm_year, dt->tm_wday);

	buf[0] = 0;		/* reg offset */
	buf[1] = BIN2BCD(dt->tm_sec);
	buf[2] = BIN2BCD(dt->tm_min);
	buf[3] = BIN2BCD(dt->tm_hour);
	buf[4] = BIN2BCD(dt->tm_wday + 1);
	buf[5] = BIN2BCD(dt->tm_mday);
	buf[6] = BIN2BCD(dt->tm_mon + 1);
	val = dt->tm_year;
	if (val >= 100) {
		val -= 100;
		buf[6] |= (1 << 7);
	}
	buf[7] = BIN2BCD(val);

	msg[0].addr = client->addr;
	msg[0].flags = 0;
	msg[0].len = sizeof(buf);
	msg[0].buf = &buf[0];

	result = i2c_transfer(client->adapter, msg, 1);
	if (result == 1)
		return 0;

	dev_err(&client->dev, "error writing data! %d\n", result);
	return -EIO;
}

static int ds1337_command(struct i2c_client *client, unsigned int cmd,
			  void *arg)
{
	dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);

	switch (cmd) {
	case DS1337_GET_DATE:
		return ds1337_get_datetime(client, arg);

	case DS1337_SET_DATE:
		return ds1337_set_datetime(client, arg);

	default:
		return -EINVAL;
	}
}

/*
 * Public API for access to specific device. Useful for low-level
 * RTC access from kernel code.
 */
int ds1337_do_command(int bus, int cmd, void *arg)
{
	struct list_head *walk;
	struct list_head *tmp;
	struct ds1337_data *data;

	list_for_each_safe(walk, tmp, &ds1337_clients) {
		data = list_entry(walk, struct ds1337_data, list);
		if (data->client.adapter->nr == bus)
			return ds1337_command(&data->client, cmd, arg);
	}

	return -ENODEV;
}

static int ds1337_attach_adapter(struct i2c_adapter *adapter)
{
	return i2c_probe(adapter, &addr_data, ds1337_detect);
}

/*
 * The following function does more than just detection. If detection
 * succeeds, it also registers the new chip.
 */
static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
{
	struct i2c_client *new_client;
	struct ds1337_data *data;
	int err = 0;
	const char *name = "";

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
				     I2C_FUNC_I2C))
		goto exit;

	if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
		err = -ENOMEM;
		goto exit;
	}
	INIT_LIST_HEAD(&data->list);

	/* The common I2C client data is placed right before the
	 * DS1337-specific data. 
	 */
	new_client = &data->client;
	i2c_set_clientdata(new_client, data);
	new_client->addr = address;
	new_client->adapter = adapter;
	new_client->driver = &ds1337_driver;
	new_client->flags = 0;

	/*
	 * Now we do the remaining detection. A negative kind means that
	 * the driver was loaded with no force parameter (default), so we
	 * must both detect and identify the chip. A zero kind means that
	 * the driver was loaded with the force parameter, the detection
	 * step shall be skipped. A positive kind means that the driver
	 * was loaded with the force parameter and a given kind of chip is
	 * requested, so both the detection and the identification steps
	 * are skipped.
	 *
	 * For detection, we read registers that are most likely to cause
	 * detection failure, i.e. those that have more bits with fixed
	 * or reserved values.
	 */

	/* Default to an DS1337 if forced */
	if (kind == 0)
		kind = ds1337;

	if (kind < 0) {		/* detection and identification */
		u8 data;

		/* Check that status register bits 6-2 are zero */
		if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) ||
		    (data & 0x7c))
			goto exit_free;

		/* Check for a valid day register value */
		if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) ||
		    (data == 0) || (data & 0xf8))
			goto exit_free;

		/* Check for a valid date register value */
		if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) ||
		    (data == 0) || (data & 0xc0) || ((data & 0x0f) > 9) ||
		    (data >= 0x32))
			goto exit_free;

		/* Check for a valid month register value */
		if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) ||
		    (data == 0) || (data & 0x60) || ((data & 0x0f) > 9) ||
		    ((data >= 0x13) && (data <= 0x19)))
			goto exit_free;

		/* Check that control register bits 6-5 are zero */
		if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) ||
		    (data & 0x60))
			goto exit_free;

		kind = ds1337;
	}

	if (kind == ds1337)
		name = "ds1337";

	/* We can fill in the remaining client fields */
	strlcpy(new_client->name, name, I2C_NAME_SIZE);

	/* Tell the I2C layer a new client has arrived */
	if ((err = i2c_attach_client(new_client)))
		goto exit_free;

	/* Initialize the DS1337 chip */
	ds1337_init_client(new_client);

	/* Add client to local list */
	list_add(&data->list, &ds1337_clients);

	return 0;

exit_free:
	kfree(data);
exit:
	return err;
}

static void ds1337_init_client(struct i2c_client *client)
{
	u8 status, control;

	/* On some boards, the RTC isn't configured by boot firmware.
	 * Handle that case by starting/configuring the RTC now.
	 */
	status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
	control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);

	if ((status & 0x80) || (control & 0x80)) {
		/* RTC not running */
		u8 buf[16];
		struct i2c_msg msg[1];

		dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);

		/* Initialize all, including STATUS and CONTROL to zero */
		memset(buf, 0, sizeof(buf));
		msg[0].addr = client->addr;
		msg[0].flags = 0;
		msg[0].len = sizeof(buf);
		msg[0].buf = &buf[0];

		i2c_transfer(client->adapter, msg, 1);
	} else {
		/* Running: ensure that device is set in 24-hour mode */
		s32 val;

		val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
		if ((val >= 0) && (val & (1 << 6)))
			i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
						  val & 0x3f);
	}
}

static int ds1337_detach_client(struct i2c_client *client)
{
	int err;
	struct ds1337_data *data = i2c_get_clientdata(client);

	if ((err = i2c_detach_client(client)))
		return err;

	list_del(&data->list);
	kfree(data);
	return 0;
}

static int __init ds1337_init(void)
{
	return i2c_add_driver(&ds1337_driver);
}

static void __exit ds1337_exit(void)
{
	i2c_del_driver(&ds1337_driver);
}

MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("DS1337 RTC driver");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL_GPL(ds1337_do_command);

module_init(ds1337_init);
module_exit(ds1337_exit);