summaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-ds1347.c
blob: 157bf5209ac40bc468717285182f857ade1f0a4c (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
// SPDX-License-Identifier: GPL-2.0-only
/* rtc-ds1347.c
 *
 * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
 * Real Time Clock
 *
 * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
 */

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

/* Registers in ds1347 rtc */

#define DS1347_SECONDS_REG	0x01
#define DS1347_MINUTES_REG	0x03
#define DS1347_HOURS_REG	0x05
#define DS1347_DATE_REG		0x07
#define DS1347_MONTH_REG	0x09
#define DS1347_DAY_REG		0x0B
#define DS1347_YEAR_REG		0x0D
#define DS1347_CONTROL_REG	0x0F
#define DS1347_CENTURY_REG	0x13
#define DS1347_STATUS_REG	0x17
#define DS1347_CLOCK_BURST	0x3F

#define DS1347_WP_BIT		BIT(7)

#define DS1347_NEOSC_BIT	BIT(7)
#define DS1347_OSF_BIT		BIT(2)

static const struct regmap_range ds1347_ranges[] = {
	{
		.range_min = DS1347_SECONDS_REG,
		.range_max = DS1347_STATUS_REG,
	},
};

static const struct regmap_access_table ds1347_access_table = {
	.yes_ranges = ds1347_ranges,
	.n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
};

static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
{
	struct regmap *map = dev_get_drvdata(dev);
	unsigned int status, century, secs;
	unsigned char buf[8];
	int err;

	err = regmap_read(map, DS1347_STATUS_REG, &status);
	if (err)
		return err;

	if (status & DS1347_OSF_BIT)
		return -EINVAL;

	do {
		err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
		if (err)
			return err;

		err = regmap_read(map, DS1347_CENTURY_REG, &century);
		if (err)
			return err;

		err = regmap_read(map, DS1347_SECONDS_REG, &secs);
		if (err)
			return err;
	} while (buf[0] != secs);

	dt->tm_sec = bcd2bin(buf[0]);
	dt->tm_min = bcd2bin(buf[1] & 0x7f);
	dt->tm_hour = bcd2bin(buf[2] & 0x3F);
	dt->tm_mday = bcd2bin(buf[3]);
	dt->tm_mon = bcd2bin(buf[4]) - 1;
	dt->tm_wday = bcd2bin(buf[5]) - 1;
	dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;

	return 0;
}

static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
{
	struct regmap *map = dev_get_drvdata(dev);
	unsigned int century;
	unsigned char buf[8];
	int err;

	err = regmap_update_bits(map, DS1347_STATUS_REG,
				 DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);
	if (err)
		return err;

	buf[0] = bin2bcd(dt->tm_sec);
	buf[1] = bin2bcd(dt->tm_min);
	buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
	buf[3] = bin2bcd(dt->tm_mday);
	buf[4] = bin2bcd(dt->tm_mon + 1);
	buf[5] = bin2bcd(dt->tm_wday + 1);
	buf[6] = bin2bcd(dt->tm_year % 100);
	buf[7] = bin2bcd(0x00);

	err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
	if (err)
		return err;

	century = (dt->tm_year / 100) + 19;
	err = regmap_write(map, DS1347_CENTURY_REG, century);
	if (err)
		return err;

	return regmap_update_bits(map, DS1347_STATUS_REG,
				  DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
}

static const struct rtc_class_ops ds1347_rtc_ops = {
	.read_time = ds1347_read_time,
	.set_time = ds1347_set_time,
};

static int ds1347_probe(struct spi_device *spi)
{
	struct rtc_device *rtc;
	struct regmap_config config;
	struct regmap *map;
	int err;

	memset(&config, 0, sizeof(config));
	config.reg_bits = 8;
	config.val_bits = 8;
	config.read_flag_mask = 0x80;
	config.max_register = 0x3F;
	config.wr_table = &ds1347_access_table;

	/* spi setup with ds1347 in mode 3 and bits per word as 8 */
	spi->mode = SPI_MODE_3;
	spi->bits_per_word = 8;
	spi_setup(spi);

	map = devm_regmap_init_spi(spi, &config);

	if (IS_ERR(map)) {
		dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
		return PTR_ERR(map);
	}

	spi_set_drvdata(spi, map);

	/* Disable the write protect of rtc */
	err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0);
	if (err)
		return err;

	rtc = devm_rtc_allocate_device(&spi->dev);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	rtc->ops = &ds1347_rtc_ops;
	rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
	rtc->range_max = RTC_TIMESTAMP_END_9999;

	return devm_rtc_register_device(rtc);
}

static struct spi_driver ds1347_driver = {
	.driver = {
		.name = "ds1347",
	},
	.probe = ds1347_probe,
};

module_spi_driver(ds1347_driver);

MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
MODULE_LICENSE("GPL v2");