diff options
Diffstat (limited to 'drivers/rtc/rtc-ds1347.c')
| -rw-r--r-- | drivers/rtc/rtc-ds1347.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c new file mode 100644 index 000000000..a40c1a52d --- /dev/null +++ b/drivers/rtc/rtc-ds1347.c @@ -0,0 +1,183 @@ +// 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_CENTURY_REG 0x13 +#define DS1347_STATUS_REG 0x17 +#define DS1347_CLOCK_BURST 0x3F + +#define DS1347_WP_BIT BIT(7) + +#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, century, secs; + unsigned char buf[8]; + int err; + + err = regmap_read(map, DS1347_STATUS_REG, &status); + if (err) + return err; + + if (status & DS1347_OSF_BIT) + return -EINVAL; + + do { + err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8); + if (err) + return err; + + err = regmap_read(map, DS1347_CENTURY_REG, ¢ury); + if (err) + return err; + + err = regmap_read(map, DS1347_SECONDS_REG, &secs); + if (err) + return err; + } while (buf[0] != secs); + + 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(century) * 100) + bcd2bin(buf[6]) - 1900; + + return 0; +} + +static int ds1347_set_time(struct device *dev, struct rtc_time *dt) +{ + struct regmap *map = dev_get_drvdata(dev); + unsigned int century; + 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); + buf[6] = bin2bcd(dt->tm_year % 100); + buf[7] = bin2bcd(0x00); + + err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8); + if (err) + return err; + + century = (dt->tm_year / 100) + 19; + err = regmap_write(map, DS1347_CENTURY_REG, bin2bcd(century)); + 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; + int err; + + 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 */ + err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0); + if (err) + return err; + + 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 devm_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"); |