// 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, 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");