aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/rtc/rtc-ds3234.c
blob: 37d131d03f33c19ad17d744ac3d1106ea2067641 (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
/* drivers/rtc/rtc-ds3234.c
 *
 * Driver for Dallas Semiconductor (DS3234) SPI RTC with Integrated Crystal
 * and SRAM.
 *
 * Copyright (C) 2008 MIMOMax Wireless Ltd.
 *
 * 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.
 *
 * Changelog:
 *
 * 07-May-2008: Dennis Aberilla <denzzzhome@yahoo.com>
 *		- Created based on the max6902 code. Only implements the
 *		  date/time keeping functions; no SRAM yet.
 */

#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>

#define DS3234_REG_SECONDS	0x00
#define DS3234_REG_MINUTES	0x01
#define DS3234_REG_HOURS	0x02
#define DS3234_REG_DAY		0x03
#define DS3234_REG_DATE		0x04
#define DS3234_REG_MONTH	0x05
#define DS3234_REG_YEAR		0x06
#define DS3234_REG_CENTURY	(1 << 7) /* Bit 7 of the Month register */

#define DS3234_REG_CONTROL	0x0E
#define DS3234_REG_CONT_STAT	0x0F

#undef DS3234_DEBUG

struct ds3234 {
	struct rtc_device *rtc;
	u8 buf[8]; /* Burst read: addr + 7 regs */
	u8 tx_buf[2];
	u8 rx_buf[2];
};

static void ds3234_set_reg(struct device *dev, unsigned char address,
				unsigned char data)
{
	struct spi_device *spi = to_spi_device(dev);
	unsigned char buf[2];

	/* MSB must be '1' to indicate write */
	buf[0] = address | 0x80;
	buf[1] = data;

	spi_write(spi, buf, 2);
}

static int ds3234_get_reg(struct device *dev, unsigned char address,
				unsigned char *data)
{
	struct spi_device *spi = to_spi_device(dev);
	struct ds3234 *chip = dev_get_drvdata(dev);
	struct spi_message message;
	struct spi_transfer xfer;
	int status;

	if (!data)
		return -EINVAL;

	/* Build our spi message */
	spi_message_init(&message);
	memset(&xfer, 0, sizeof(xfer));

	/* Address + dummy tx byte */
	xfer.len = 2;
	xfer.tx_buf = chip->tx_buf;
	xfer.rx_buf = chip->rx_buf;

	chip->tx_buf[0] = address;
	chip->tx_buf[1] = 0xff;

	spi_message_add_tail(&xfer, &message);

	/* do the i/o */
	status = spi_sync(spi, &message);
	if (status == 0)
		status = message.status;
	else
		return status;

	*data = chip->rx_buf[1];

	return status;
}

static int ds3234_get_datetime(struct device *dev, struct rtc_time *dt)
{
	struct spi_device *spi = to_spi_device(dev);
	struct ds3234 *chip = dev_get_drvdata(dev);
	struct spi_message message;
	struct spi_transfer xfer;
	int status;

	/* build the message */
	spi_message_init(&message);
	memset(&xfer, 0, sizeof(xfer));
	xfer.len = 1 + 7;	/* Addr + 7 registers */
	xfer.tx_buf = chip->buf;
	xfer.rx_buf = chip->buf;
	chip->buf[0] = 0x00;	/* Start address */
	spi_message_add_tail(&xfer, &message);

	/* do the i/o */
	status = spi_sync(spi, &message);
	if (status == 0)
		status = message.status;
	else
		return status;

	/* Seconds, Minutes, Hours, Day, Date, Month, Year */
	dt->tm_sec	= bcd2bin(chip->buf[1]);
	dt->tm_min	= bcd2bin(chip->buf[2]);
	dt->tm_hour	= bcd2bin(chip->buf[3] & 0x3f);
	dt->tm_wday	= bcd2bin(chip->buf[4]) - 1; /* 0 = Sun */
	dt->tm_mday	= bcd2bin(chip->buf[5]);
	dt->tm_mon	= bcd2bin(chip->buf[6] & 0x1f) - 1; /* 0 = Jan */
	dt->tm_year 	= bcd2bin(chip->buf[7] & 0xff) + 100; /* Assume 20YY */

#ifdef DS3234_DEBUG
	dev_dbg(dev, "\n%s : Read RTC values\n", __func__);
	dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
	dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
	dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
	dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
	dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
	dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
	dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
#endif

	return 0;
}

static int ds3234_set_datetime(struct device *dev, struct rtc_time *dt)
{
#ifdef DS3234_DEBUG
	dev_dbg(dev, "\n%s : Setting RTC values\n", __func__);
	dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
	dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
	dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
	dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
	dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
	dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
	dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
#endif

	ds3234_set_reg(dev, DS3234_REG_SECONDS, bin2bcd(dt->tm_sec));
	ds3234_set_reg(dev, DS3234_REG_MINUTES, bin2bcd(dt->tm_min));
	ds3234_set_reg(dev, DS3234_REG_HOURS, bin2bcd(dt->tm_hour) & 0x3f);

	/* 0 = Sun */
	ds3234_set_reg(dev, DS3234_REG_DAY, bin2bcd(dt->tm_wday + 1));
	ds3234_set_reg(dev, DS3234_REG_DATE, bin2bcd(dt->tm_mday));

	/* 0 = Jan */
	ds3234_set_reg(dev, DS3234_REG_MONTH, bin2bcd(dt->tm_mon + 1));

	/* Assume 20YY although we just want to make sure not to go negative. */
	if (dt->tm_year > 100)
		dt->tm_year -= 100;

	ds3234_set_reg(dev, DS3234_REG_YEAR, bin2bcd(dt->tm_year));

	return 0;
}

static int ds3234_read_time(struct device *dev, struct rtc_time *tm)
{
	return ds3234_get_datetime(dev, tm);
}

static int ds3234_set_time(struct device *dev, struct rtc_time *tm)
{
	return ds3234_set_datetime(dev, tm);
}

static const struct rtc_class_ops ds3234_rtc_ops = {
	.read_time	= ds3234_read_time,
	.set_time	= ds3234_set_time,
};

static int ds3234_probe(struct spi_device *spi)
{
	struct rtc_device *rtc;
	unsigned char tmp;
	struct ds3234 *chip;
	int res;

	rtc = rtc_device_register("ds3234",
				&spi->dev, &ds3234_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	spi->mode = SPI_MODE_3;
	spi->bits_per_word = 8;
	spi_setup(spi);

	chip = kzalloc(sizeof(struct ds3234), GFP_KERNEL);
	if (!chip) {
		rtc_device_unregister(rtc);
		return -ENOMEM;
	}
	chip->rtc = rtc;
	dev_set_drvdata(&spi->dev, chip);

	res = ds3234_get_reg(&spi->dev, DS3234_REG_SECONDS, &tmp);
	if (res) {
		rtc_device_unregister(rtc);
		return res;
	}

	/* Control settings
	 *
	 * CONTROL_REG
	 * BIT 7	6	5	4	3	2	1	0
	 *     EOSC	BBSQW	CONV	RS2	RS1	INTCN	A2IE	A1IE
	 *
	 *     0	0	0	1	1	1	0	0
	 *
	 * CONTROL_STAT_REG
	 * BIT 7	6	5	4	3	2	1	0
	 *     OSF	BB32kHz	CRATE1	CRATE0	EN32kHz	BSY	A2F	A1F
	 *
	 *     1	0	0	0	1	0	0	0
	 */
	ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
	ds3234_set_reg(&spi->dev, DS3234_REG_CONTROL, tmp & 0x1c);

	ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
	ds3234_set_reg(&spi->dev, DS3234_REG_CONT_STAT, tmp & 0x88);

	/* Print our settings */
	ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
	dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);

	ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
	dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);

	return 0;
}

static int __exit ds3234_remove(struct spi_device *spi)
{
	struct ds3234 *chip = platform_get_drvdata(spi);
	struct rtc_device *rtc = chip->rtc;

	if (rtc)
		rtc_device_unregister(rtc);

	kfree(chip);

	return 0;
}

static struct spi_driver ds3234_driver = {
	.driver = {
		.name	 = "ds3234",
		.bus	= &spi_bus_type,
		.owner	= THIS_MODULE,
	},
	.probe	 = ds3234_probe,
	.remove = __devexit_p(ds3234_remove),
};

static __init int ds3234_init(void)
{
	printk(KERN_INFO "DS3234 SPI RTC Driver\n");
	return spi_register_driver(&ds3234_driver);
}
module_init(ds3234_init);

static __exit void ds3234_exit(void)
{
	spi_unregister_driver(&ds3234_driver);
}
module_exit(ds3234_exit);

MODULE_DESCRIPTION("DS3234 SPI RTC driver");
MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
MODULE_LICENSE("GPL");