/* rtc-ds1347.c * * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible * Real Time Clock * * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #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> /* 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 static int ds1347_read_reg(struct device *dev, unsigned char address, unsigned char *data) { struct spi_device *spi = to_spi_device(dev); *data = address | 0x80; return spi_write_then_read(spi, data, 1, data, 1); } static int ds1347_write_reg(struct device *dev, unsigned char address, unsigned char data) { struct spi_device *spi = to_spi_device(dev); unsigned char buf[2]; buf[0] = address & 0x7F; buf[1] = data; return spi_write_then_read(spi, buf, 2, NULL, 0); } static int ds1347_read_time(struct device *dev, struct rtc_time *dt) { struct spi_device *spi = to_spi_device(dev); int err; unsigned char buf[8]; buf[0] = DS1347_CLOCK_BURST | 0x80; err = spi_write_then_read(spi, buf, 1, buf, 8); if (err) return err; dt->tm_sec = bcd2bin(buf[0]); dt->tm_min = bcd2bin(buf[1]); 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 rtc_valid_tm(dt); } static int ds1347_set_time(struct device *dev, struct rtc_time *dt) { struct spi_device *spi = to_spi_device(dev); unsigned char buf[9]; buf[0] = DS1347_CLOCK_BURST & 0x7F; buf[1] = bin2bcd(dt->tm_sec); buf[2] = bin2bcd(dt->tm_min); buf[3] = (bin2bcd(dt->tm_hour) & 0x3F); buf[4] = bin2bcd(dt->tm_mday); buf[5] = bin2bcd(dt->tm_mon + 1); buf[6] = 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[7] = bin2bcd(dt->tm_year); buf[8] = bin2bcd(0x00); /* write the rtc settings */ return spi_write_then_read(spi, buf, 9, NULL, 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; unsigned char data; int res; /* 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); /* RTC Settings */ res = ds1347_read_reg(&spi->dev, DS1347_SECONDS_REG, &data); if (res) return res; /* Disable the write protect of rtc */ ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data); data = data & ~(1<<7); ds1347_write_reg(&spi->dev, DS1347_CONTROL_REG, data); /* Enable the oscillator , disable the oscillator stop flag, and glitch filter to reduce current consumption */ ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data); data = data & 0x1B; ds1347_write_reg(&spi->dev, DS1347_STATUS_REG, data); /* display the settings */ ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data); dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data); ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data); dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data); rtc = devm_rtc_device_register(&spi->dev, "ds1347", &ds1347_rtc_ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc); spi_set_drvdata(spi, rtc); return 0; } static struct spi_driver ds1347_driver = { .driver = { .name = "ds1347", .owner = THIS_MODULE, }, .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");