1/* rtc-ds1347.c
  2 *
  3 * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
  4 * Real Time Clock
  5 *
  6 * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License version 2 as
 10 * published by the Free Software Foundation.
 11 *
 12 */
 13
 14#include <linux/init.h>
 15#include <linux/module.h>
 16#include <linux/device.h>
 17#include <linux/platform_device.h>
 18#include <linux/rtc.h>
 19#include <linux/spi/spi.h>
 20#include <linux/bcd.h>
 21#include <linux/regmap.h>
 22
 23/* Registers in ds1347 rtc */
 24
 25#define DS1347_SECONDS_REG	0x01
 26#define DS1347_MINUTES_REG	0x03
 27#define DS1347_HOURS_REG	0x05
 28#define DS1347_DATE_REG		0x07
 29#define DS1347_MONTH_REG	0x09
 30#define DS1347_DAY_REG		0x0B
 31#define DS1347_YEAR_REG		0x0D
 32#define DS1347_CONTROL_REG	0x0F
 33#define DS1347_STATUS_REG	0x17
 34#define DS1347_CLOCK_BURST	0x3F
 35
 36static const struct regmap_range ds1347_ranges[] = {
 37	{
 38		.range_min = DS1347_SECONDS_REG,
 39		.range_max = DS1347_STATUS_REG,
 40	},
 41};
 42
 43static const struct regmap_access_table ds1347_access_table = {
 44	.yes_ranges = ds1347_ranges,
 45	.n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
 46};
 47
 48static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 49{
 50	struct spi_device *spi = to_spi_device(dev);
 51	struct regmap *map;
 52	int err;
 53	unsigned char buf[8];
 54
 55	map = spi_get_drvdata(spi);
 56
 57	err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
 58	if (err)
 59		return err;
 60
 61	dt->tm_sec = bcd2bin(buf[0]);
 62	dt->tm_min = bcd2bin(buf[1]);
 63	dt->tm_hour = bcd2bin(buf[2] & 0x3F);
 64	dt->tm_mday = bcd2bin(buf[3]);
 65	dt->tm_mon = bcd2bin(buf[4]) - 1;
 66	dt->tm_wday = bcd2bin(buf[5]) - 1;
 67	dt->tm_year = bcd2bin(buf[6]) + 100;
 68
 69	return 0;
 70}
 71
 72static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
 73{
 74	struct spi_device *spi = to_spi_device(dev);
 75	struct regmap *map;
 76	unsigned char buf[8];
 77
 78	map = spi_get_drvdata(spi);
 79
 80	buf[0] = bin2bcd(dt->tm_sec);
 81	buf[1] = bin2bcd(dt->tm_min);
 82	buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
 83	buf[3] = bin2bcd(dt->tm_mday);
 84	buf[4] = bin2bcd(dt->tm_mon + 1);
 85	buf[5] = bin2bcd(dt->tm_wday + 1);
 86
 87	/* year in linux is from 1900 i.e in range of 100
 88	in rtc it is from 00 to 99 */
 89	dt->tm_year = dt->tm_year % 100;
 90
 91	buf[6] = bin2bcd(dt->tm_year);
 92	buf[7] = bin2bcd(0x00);
 93
 94	/* write the rtc settings */
 95	return regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
 96}
 97
 98static const struct rtc_class_ops ds1347_rtc_ops = {
 99	.read_time = ds1347_read_time,
100	.set_time = ds1347_set_time,
101};
102
103static int ds1347_probe(struct spi_device *spi)
104{
105	struct rtc_device *rtc;
106	struct regmap_config config;
107	struct regmap *map;
108	unsigned int data;
109	int res;
110
111	memset(&config, 0, sizeof(config));
112	config.reg_bits = 8;
113	config.val_bits = 8;
114	config.read_flag_mask = 0x80;
115	config.max_register = 0x3F;
116	config.wr_table = &ds1347_access_table;
117
118	/* spi setup with ds1347 in mode 3 and bits per word as 8 */
119	spi->mode = SPI_MODE_3;
120	spi->bits_per_word = 8;
121	spi_setup(spi);
122
123	map = devm_regmap_init_spi(spi, &config);
124
125	if (IS_ERR(map)) {
126		dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
127		return PTR_ERR(map);
128	}
129
130	spi_set_drvdata(spi, map);
131
132	/* RTC Settings */
133	res = regmap_read(map, DS1347_SECONDS_REG, &data);
134	if (res)
135		return res;
136
137	/* Disable the write protect of rtc */
138	regmap_read(map, DS1347_CONTROL_REG, &data);
139	data = data & ~(1<<7);
140	regmap_write(map, DS1347_CONTROL_REG, data);
141
142	/* Enable the oscillator , disable the oscillator stop flag,
143	 and glitch filter to reduce current consumption */
144	regmap_read(map, DS1347_STATUS_REG, &data);
145	data = data & 0x1B;
146	regmap_write(map, DS1347_STATUS_REG, data);
147
148	/* display the settings */
149	regmap_read(map, DS1347_CONTROL_REG, &data);
150	dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
151
152	regmap_read(map, DS1347_STATUS_REG, &data);
153	dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
154
155	rtc = devm_rtc_device_register(&spi->dev, "ds1347",
156				&ds1347_rtc_ops, THIS_MODULE);
157
158	if (IS_ERR(rtc))
159		return PTR_ERR(rtc);
160
161	return 0;
162}
163
164static struct spi_driver ds1347_driver = {
165	.driver = {
166		.name = "ds1347",
167	},
168	.probe = ds1347_probe,
169};
170
171module_spi_driver(ds1347_driver);
172
173MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
174MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
175MODULE_LICENSE("GPL v2");