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");