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, &century);
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