1 // SPDX-License-Identifier: GPL-2.0-only
2 /* rtc-ds1347.c
3 *
4 * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
5 * Real Time Clock
6 *
7 * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
8 */
9
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/device.h>
13 #include <linux/platform_device.h>
14 #include <linux/rtc.h>
15 #include <linux/spi/spi.h>
16 #include <linux/bcd.h>
17 #include <linux/regmap.h>
18
19 /* Registers in ds1347 rtc */
20
21 #define DS1347_SECONDS_REG 0x01
22 #define DS1347_MINUTES_REG 0x03
23 #define DS1347_HOURS_REG 0x05
24 #define DS1347_DATE_REG 0x07
25 #define DS1347_MONTH_REG 0x09
26 #define DS1347_DAY_REG 0x0B
27 #define DS1347_YEAR_REG 0x0D
28 #define DS1347_CONTROL_REG 0x0F
29 #define DS1347_CENTURY_REG 0x13
30 #define DS1347_STATUS_REG 0x17
31 #define DS1347_CLOCK_BURST 0x3F
32
33 #define DS1347_WP_BIT BIT(7)
34
35 #define DS1347_NEOSC_BIT BIT(7)
36 #define DS1347_OSF_BIT BIT(2)
37
38 static const struct regmap_range ds1347_ranges[] = {
39 {
40 .range_min = DS1347_SECONDS_REG,
41 .range_max = DS1347_STATUS_REG,
42 },
43 };
44
45 static const struct regmap_access_table ds1347_access_table = {
46 .yes_ranges = ds1347_ranges,
47 .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
48 };
49
ds1347_read_time(struct device * dev,struct rtc_time * dt)50 static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
51 {
52 struct regmap *map = dev_get_drvdata(dev);
53 unsigned int status, century, secs;
54 unsigned char buf[8];
55 int err;
56
57 err = regmap_read(map, DS1347_STATUS_REG, &status);
58 if (err)
59 return err;
60
61 if (status & DS1347_OSF_BIT)
62 return -EINVAL;
63
64 do {
65 err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
66 if (err)
67 return err;
68
69 err = regmap_read(map, DS1347_CENTURY_REG, ¢ury);
70 if (err)
71 return err;
72
73 err = regmap_read(map, DS1347_SECONDS_REG, &secs);
74 if (err)
75 return err;
76 } while (buf[0] != secs);
77
78 dt->tm_sec = bcd2bin(buf[0]);
79 dt->tm_min = bcd2bin(buf[1] & 0x7f);
80 dt->tm_hour = bcd2bin(buf[2] & 0x3F);
81 dt->tm_mday = bcd2bin(buf[3]);
82 dt->tm_mon = bcd2bin(buf[4]) - 1;
83 dt->tm_wday = bcd2bin(buf[5]) - 1;
84 dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;
85
86 return 0;
87 }
88
ds1347_set_time(struct device * dev,struct rtc_time * dt)89 static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
90 {
91 struct regmap *map = dev_get_drvdata(dev);
92 unsigned int century;
93 unsigned char buf[8];
94 int err;
95
96 err = regmap_update_bits(map, DS1347_STATUS_REG,
97 DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);
98 if (err)
99 return err;
100
101 buf[0] = bin2bcd(dt->tm_sec);
102 buf[1] = bin2bcd(dt->tm_min);
103 buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
104 buf[3] = bin2bcd(dt->tm_mday);
105 buf[4] = bin2bcd(dt->tm_mon + 1);
106 buf[5] = bin2bcd(dt->tm_wday + 1);
107 buf[6] = bin2bcd(dt->tm_year % 100);
108 buf[7] = bin2bcd(0x00);
109
110 err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
111 if (err)
112 return err;
113
114 century = (dt->tm_year / 100) + 19;
115 err = regmap_write(map, DS1347_CENTURY_REG, bin2bcd(century));
116 if (err)
117 return err;
118
119 return regmap_update_bits(map, DS1347_STATUS_REG,
120 DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
121 }
122
123 static const struct rtc_class_ops ds1347_rtc_ops = {
124 .read_time = ds1347_read_time,
125 .set_time = ds1347_set_time,
126 };
127
ds1347_probe(struct spi_device * spi)128 static int ds1347_probe(struct spi_device *spi)
129 {
130 struct rtc_device *rtc;
131 struct regmap_config config;
132 struct regmap *map;
133 int err;
134
135 memset(&config, 0, sizeof(config));
136 config.reg_bits = 8;
137 config.val_bits = 8;
138 config.read_flag_mask = 0x80;
139 config.max_register = 0x3F;
140 config.wr_table = &ds1347_access_table;
141
142 /* spi setup with ds1347 in mode 3 and bits per word as 8 */
143 spi->mode = SPI_MODE_3;
144 spi->bits_per_word = 8;
145 spi_setup(spi);
146
147 map = devm_regmap_init_spi(spi, &config);
148
149 if (IS_ERR(map)) {
150 dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
151 return PTR_ERR(map);
152 }
153
154 spi_set_drvdata(spi, map);
155
156 /* Disable the write protect of rtc */
157 err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0);
158 if (err)
159 return err;
160
161 rtc = devm_rtc_allocate_device(&spi->dev);
162 if (IS_ERR(rtc))
163 return PTR_ERR(rtc);
164
165 rtc->ops = &ds1347_rtc_ops;
166 rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
167 rtc->range_max = RTC_TIMESTAMP_END_9999;
168
169 return devm_rtc_register_device(rtc);
170 }
171
172 static struct spi_driver ds1347_driver = {
173 .driver = {
174 .name = "ds1347",
175 },
176 .probe = ds1347_probe,
177 };
178
179 module_spi_driver(ds1347_driver);
180
181 MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
182 MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
183 MODULE_LICENSE("GPL v2");
184