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// SPDX-License-Identifier: GPL-2.0-only
/* rtc-ds1347.c
*
* Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
* Real Time Clock
*
* Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#include <linux/regmap.h>
/* Registers in ds1347 rtc */
#define DS1347_SECONDS_REG 0x01
#define DS1347_MINUTES_REG 0x03
#define DS1347_HOURS_REG 0x05
#define DS1347_DATE_REG 0x07
#define DS1347_MONTH_REG 0x09
#define DS1347_DAY_REG 0x0B
#define DS1347_YEAR_REG 0x0D
#define DS1347_CONTROL_REG 0x0F
#define DS1347_STATUS_REG 0x17
#define DS1347_CLOCK_BURST 0x3F
#define DS1347_NEOSC_BIT BIT(7)
#define DS1347_OSF_BIT BIT(2)
static const struct regmap_range ds1347_ranges[] = {
{
.range_min = DS1347_SECONDS_REG,
.range_max = DS1347_STATUS_REG,
},
};
static const struct regmap_access_table ds1347_access_table = {
.yes_ranges = ds1347_ranges,
.n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
};
static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
{
struct regmap *map = dev_get_drvdata(dev);
unsigned int status;
int err;
unsigned char buf[8];
err = regmap_read(map, DS1347_STATUS_REG, &status);
if (err)
return err;
if (status & DS1347_OSF_BIT)
return -EINVAL;
err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
if (err)
return err;
dt->tm_sec = bcd2bin(buf[0]);
dt->tm_min = bcd2bin(buf[1] & 0x7f);
dt->tm_hour = bcd2bin(buf[2] & 0x3F);
dt->tm_mday = bcd2bin(buf[3]);
dt->tm_mon = bcd2bin(buf[4]) - 1;
dt->tm_wday = bcd2bin(buf[5]) - 1;
dt->tm_year = bcd2bin(buf[6]) + 100;
return 0;
}
static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
{
struct regmap *map = dev_get_drvdata(dev);
unsigned char buf[8];
int err;
err = regmap_update_bits(map, DS1347_STATUS_REG,
DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);
if (err)
return err;
buf[0] = bin2bcd(dt->tm_sec);
buf[1] = bin2bcd(dt->tm_min);
buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
buf[3] = bin2bcd(dt->tm_mday);
buf[4] = bin2bcd(dt->tm_mon + 1);
buf[5] = bin2bcd(dt->tm_wday + 1);
/* year in linux is from 1900 i.e in range of 100
in rtc it is from 00 to 99 */
dt->tm_year = dt->tm_year % 100;
buf[6] = bin2bcd(dt->tm_year);
buf[7] = bin2bcd(0x00);
/* write the rtc settings */
err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
if (err)
return err;
return regmap_update_bits(map, DS1347_STATUS_REG,
DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
}
static const struct rtc_class_ops ds1347_rtc_ops = {
.read_time = ds1347_read_time,
.set_time = ds1347_set_time,
};
static int ds1347_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
struct regmap_config config;
struct regmap *map;
unsigned int data;
memset(&config, 0, sizeof(config));
config.reg_bits = 8;
config.val_bits = 8;
config.read_flag_mask = 0x80;
config.max_register = 0x3F;
config.wr_table = &ds1347_access_table;
/* spi setup with ds1347 in mode 3 and bits per word as 8 */
spi->mode = SPI_MODE_3;
spi->bits_per_word = 8;
spi_setup(spi);
map = devm_regmap_init_spi(spi, &config);
if (IS_ERR(map)) {
dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
return PTR_ERR(map);
}
spi_set_drvdata(spi, map);
/* Disable the write protect of rtc */
regmap_read(map, DS1347_CONTROL_REG, &data);
data = data & ~(1<<7);
regmap_write(map, DS1347_CONTROL_REG, data);
rtc = devm_rtc_allocate_device(&spi->dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
rtc->ops = &ds1347_rtc_ops;
rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
rtc->range_max = RTC_TIMESTAMP_END_9999;
return rtc_register_device(rtc);
}
static struct spi_driver ds1347_driver = {
.driver = {
.name = "ds1347",
},
.probe = ds1347_probe,
};
module_spi_driver(ds1347_driver);
MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
MODULE_LICENSE("GPL v2");
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