aboutsummaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-pcf8523.c
blob: be05a645f99e985ebea76a9a9903ffdead17fb4c (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
/*
 * Copyright (C) 2012 Avionic Design GmbH
 *
 * 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.
 */

#include <linux/bcd.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/of.h>

#define DRIVER_NAME "rtc-pcf8523"

#define REG_CONTROL1 0x00
#define REG_CONTROL1_CAP_SEL (1 << 7)
#define REG_CONTROL1_STOP    (1 << 5)

#define REG_CONTROL3 0x02
#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
#define REG_CONTROL3_PM_MASK 0xe0

#define REG_SECONDS  0x03
#define REG_SECONDS_OS (1 << 7)

#define REG_MINUTES  0x04
#define REG_HOURS    0x05
#define REG_DAYS     0x06
#define REG_WEEKDAYS 0x07
#define REG_MONTHS   0x08
#define REG_YEARS    0x09

struct pcf8523 {
	struct rtc_device *rtc;
};

static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
{
	struct i2c_msg msgs[2];
	u8 value = 0;
	int err;

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

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

	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	if (err < 0)
		return err;

	*valuep = value;

	return 0;
}

static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
{
	u8 buffer[2] = { reg, value };
	struct i2c_msg msg;
	int err;

	msg.addr = client->addr;
	msg.flags = 0;
	msg.len = sizeof(buffer);
	msg.buf = buffer;

	err = i2c_transfer(client->adapter, &msg, 1);
	if (err < 0)
		return err;

	return 0;
}

static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL1, &value);
	if (err < 0)
		return err;

	if (!high)
		value &= ~REG_CONTROL1_CAP_SEL;
	else
		value |= REG_CONTROL1_CAP_SEL;

	err = pcf8523_write(client, REG_CONTROL1, value);
	if (err < 0)
		return err;

	return err;
}

static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL3, &value);
	if (err < 0)
		return err;

	value = (value & ~REG_CONTROL3_PM_MASK) | pm;

	err = pcf8523_write(client, REG_CONTROL3, value);
	if (err < 0)
		return err;

	return 0;
}

static int pcf8523_stop_rtc(struct i2c_client *client)
{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL1, &value);
	if (err < 0)
		return err;

	value |= REG_CONTROL1_STOP;

	err = pcf8523_write(client, REG_CONTROL1, value);
	if (err < 0)
		return err;

	return 0;
}

static int pcf8523_start_rtc(struct i2c_client *client)
{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL1, &value);
	if (err < 0)
		return err;

	value &= ~REG_CONTROL1_STOP;

	err = pcf8523_write(client, REG_CONTROL1, value);
	if (err < 0)
		return err;

	return 0;
}

static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct i2c_client *client = to_i2c_client(dev);
	u8 start = REG_SECONDS, regs[7];
	struct i2c_msg msgs[2];
	int err;

	msgs[0].addr = client->addr;
	msgs[0].flags = 0;
	msgs[0].len = 1;
	msgs[0].buf = &start;

	msgs[1].addr = client->addr;
	msgs[1].flags = I2C_M_RD;
	msgs[1].len = sizeof(regs);
	msgs[1].buf = regs;

	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	if (err < 0)
		return err;

	if (regs[0] & REG_SECONDS_OS) {
		/*
		 * If the oscillator was stopped, try to clear the flag. Upon
		 * power-up the flag is always set, but if we cannot clear it
		 * the oscillator isn't running properly for some reason. The
		 * sensible thing therefore is to return an error, signalling
		 * that the clock cannot be assumed to be correct.
		 */

		regs[0] &= ~REG_SECONDS_OS;

		err = pcf8523_write(client, REG_SECONDS, regs[0]);
		if (err < 0)
			return err;

		err = pcf8523_read(client, REG_SECONDS, &regs[0]);
		if (err < 0)
			return err;

		if (regs[0] & REG_SECONDS_OS)
			return -EAGAIN;
	}

	tm->tm_sec = bcd2bin(regs[0] & 0x7f);
	tm->tm_min = bcd2bin(regs[1] & 0x7f);
	tm->tm_hour = bcd2bin(regs[2] & 0x3f);
	tm->tm_mday = bcd2bin(regs[3] & 0x3f);
	tm->tm_wday = regs[4] & 0x7;
	tm->tm_mon = bcd2bin(regs[5] & 0x1f);
	tm->tm_year = bcd2bin(regs[6]) + 100;

	return rtc_valid_tm(tm);
}

static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct i2c_msg msg;
	u8 regs[8];
	int err;

	err = pcf8523_stop_rtc(client);
	if (err < 0)
		return err;

	regs[0] = REG_SECONDS;
	regs[1] = bin2bcd(tm->tm_sec);
	regs[2] = bin2bcd(tm->tm_min);
	regs[3] = bin2bcd(tm->tm_hour);
	regs[4] = bin2bcd(tm->tm_mday);
	regs[5] = tm->tm_wday;
	regs[6] = bin2bcd(tm->tm_mon);
	regs[7] = bin2bcd(tm->tm_year - 100);

	msg.addr = client->addr;
	msg.flags = 0;
	msg.len = sizeof(regs);
	msg.buf = regs;

	err = i2c_transfer(client->adapter, &msg, 1);
	if (err < 0) {
		/*
		 * If the time cannot be set, restart the RTC anyway. Note
		 * that errors are ignored if the RTC cannot be started so
		 * that we have a chance to propagate the original error.
		 */
		pcf8523_start_rtc(client);
		return err;
	}

	return pcf8523_start_rtc(client);
}

static const struct rtc_class_ops pcf8523_rtc_ops = {
	.read_time = pcf8523_rtc_read_time,
	.set_time = pcf8523_rtc_set_time,
};

static int pcf8523_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct pcf8523 *pcf;
	int err;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
		return -ENODEV;

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

	err = pcf8523_select_capacitance(client, true);
	if (err < 0)
		return err;

	err = pcf8523_set_pm(client, 0);
	if (err < 0)
		return err;

	pcf->rtc = rtc_device_register(DRIVER_NAME, &client->dev,
				       &pcf8523_rtc_ops, THIS_MODULE);
	if (IS_ERR(pcf->rtc))
		return PTR_ERR(pcf->rtc);

	i2c_set_clientdata(client, pcf);

	return 0;
}

static int pcf8523_remove(struct i2c_client *client)
{
	struct pcf8523 *pcf = i2c_get_clientdata(client);

	rtc_device_unregister(pcf->rtc);

	return 0;
}

static const struct i2c_device_id pcf8523_id[] = {
	{ "pcf8523", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, pcf8523_id);

#ifdef CONFIG_OF
static const struct of_device_id pcf8523_of_match[] = {
	{ .compatible = "nxp,pcf8523" },
	{ }
};
MODULE_DEVICE_TABLE(of, pcf8523_of_match);
#endif

static struct i2c_driver pcf8523_driver = {
	.driver = {
		.name = DRIVER_NAME,
		.owner = THIS_MODULE,
		.of_match_table = of_match_ptr(pcf8523_of_match),
	},
	.probe = pcf8523_probe,
	.remove = pcf8523_remove,
	.id_table = pcf8523_id,
};
module_i2c_driver(pcf8523_driver);

MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
MODULE_LICENSE("GPL v2");