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 | |
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, val: &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, val: buf, val_count: 8); |
66 | if (err) |
67 | return err; |
68 | |
69 | err = regmap_read(map, DS1347_CENTURY_REG, val: ¢ury); |
70 | if (err) |
71 | return err; |
72 | |
73 | err = regmap_read(map, DS1347_SECONDS_REG, val: &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 | |
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, val: buf, val_count: 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, val: 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 | |
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(ptr: map)) { |
150 | dev_err(&spi->dev, "ds1347 regmap init spi failed\n" ); |
151 | return PTR_ERR(ptr: map); |
152 | } |
153 | |
154 | spi_set_drvdata(spi, data: map); |
155 | |
156 | /* Disable the write protect of rtc */ |
157 | err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, val: 0); |
158 | if (err) |
159 | return err; |
160 | |
161 | rtc = devm_rtc_allocate_device(dev: &spi->dev); |
162 | if (IS_ERR(ptr: rtc)) |
163 | return PTR_ERR(ptr: 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 | |