tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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_STATUS_REG 0x17
30#define DS1347_CLOCK_BURST 0x3F
31
32static const struct regmap_range ds1347_ranges[] = {
33 {
34 .range_min = DS1347_SECONDS_REG,
35 .range_max = DS1347_STATUS_REG,
36 },
37};
38
39static const struct regmap_access_table ds1347_access_table = {
40 .yes_ranges = ds1347_ranges,
41 .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
42};
43
44static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
45{
46 struct spi_device *spi = to_spi_device(dev);
47 struct regmap *map;
48 int err;
49 unsigned char buf[8];
50
51 map = spi_get_drvdata(spi);
52
53 err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
54 if (err)
55 return err;
56
57 dt->tm_sec = bcd2bin(buf[0]);
58 dt->tm_min = bcd2bin(buf[1]);
59 dt->tm_hour = bcd2bin(buf[2] & 0x3F);
60 dt->tm_mday = bcd2bin(buf[3]);
61 dt->tm_mon = bcd2bin(buf[4]) - 1;
62 dt->tm_wday = bcd2bin(buf[5]) - 1;
63 dt->tm_year = bcd2bin(buf[6]) + 100;
64
65 return 0;
66}
67
68static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
69{
70 struct spi_device *spi = to_spi_device(dev);
71 struct regmap *map;
72 unsigned char buf[8];
73
74 map = spi_get_drvdata(spi);
75
76 buf[0] = bin2bcd(dt->tm_sec);
77 buf[1] = bin2bcd(dt->tm_min);
78 buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
79 buf[3] = bin2bcd(dt->tm_mday);
80 buf[4] = bin2bcd(dt->tm_mon + 1);
81 buf[5] = bin2bcd(dt->tm_wday + 1);
82
83 /* year in linux is from 1900 i.e in range of 100
84 in rtc it is from 00 to 99 */
85 dt->tm_year = dt->tm_year % 100;
86
87 buf[6] = bin2bcd(dt->tm_year);
88 buf[7] = bin2bcd(0x00);
89
90 /* write the rtc settings */
91 return regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
92}
93
94static const struct rtc_class_ops ds1347_rtc_ops = {
95 .read_time = ds1347_read_time,
96 .set_time = ds1347_set_time,
97};
98
99static int ds1347_probe(struct spi_device *spi)
100{
101 struct rtc_device *rtc;
102 struct regmap_config config;
103 struct regmap *map;
104 unsigned int data;
105 int res;
106
107 memset(&config, 0, sizeof(config));
108 config.reg_bits = 8;
109 config.val_bits = 8;
110 config.read_flag_mask = 0x80;
111 config.max_register = 0x3F;
112 config.wr_table = &ds1347_access_table;
113
114 /* spi setup with ds1347 in mode 3 and bits per word as 8 */
115 spi->mode = SPI_MODE_3;
116 spi->bits_per_word = 8;
117 spi_setup(spi);
118
119 map = devm_regmap_init_spi(spi, &config);
120
121 if (IS_ERR(map)) {
122 dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
123 return PTR_ERR(map);
124 }
125
126 spi_set_drvdata(spi, map);
127
128 /* RTC Settings */
129 res = regmap_read(map, DS1347_SECONDS_REG, &data);
130 if (res)
131 return res;
132
133 /* Disable the write protect of rtc */
134 regmap_read(map, DS1347_CONTROL_REG, &data);
135 data = data & ~(1<<7);
136 regmap_write(map, DS1347_CONTROL_REG, data);
137
138 /* Enable the oscillator , disable the oscillator stop flag,
139 and glitch filter to reduce current consumption */
140 regmap_read(map, DS1347_STATUS_REG, &data);
141 data = data & 0x1B;
142 regmap_write(map, DS1347_STATUS_REG, data);
143
144 /* display the settings */
145 regmap_read(map, DS1347_CONTROL_REG, &data);
146 dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
147
148 regmap_read(map, DS1347_STATUS_REG, &data);
149 dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
150
151 rtc = devm_rtc_device_register(&spi->dev, "ds1347",
152 &ds1347_rtc_ops, THIS_MODULE);
153
154 if (IS_ERR(rtc))
155 return PTR_ERR(rtc);
156
157 return 0;
158}
159
160static struct spi_driver ds1347_driver = {
161 .driver = {
162 .name = "ds1347",
163 },
164 .probe = ds1347_probe,
165};
166
167module_spi_driver(ds1347_driver);
168
169MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
170MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
171MODULE_LICENSE("GPL v2");