166 строки
4.1 KiB
C
166 строки
4.1 KiB
C
/* rtc-ds1347.c
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*
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* Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
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* Real Time Clock
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*
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* Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/platform_device.h>
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#include <linux/rtc.h>
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#include <linux/spi/spi.h>
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#include <linux/bcd.h>
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/* Registers in ds1347 rtc */
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#define DS1347_SECONDS_REG 0x01
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#define DS1347_MINUTES_REG 0x03
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#define DS1347_HOURS_REG 0x05
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#define DS1347_DATE_REG 0x07
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#define DS1347_MONTH_REG 0x09
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#define DS1347_DAY_REG 0x0B
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#define DS1347_YEAR_REG 0x0D
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#define DS1347_CONTROL_REG 0x0F
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#define DS1347_STATUS_REG 0x17
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#define DS1347_CLOCK_BURST 0x3F
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static int ds1347_read_reg(struct device *dev, unsigned char address,
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unsigned char *data)
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{
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struct spi_device *spi = to_spi_device(dev);
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*data = address | 0x80;
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return spi_write_then_read(spi, data, 1, data, 1);
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}
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static int ds1347_write_reg(struct device *dev, unsigned char address,
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unsigned char data)
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{
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struct spi_device *spi = to_spi_device(dev);
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unsigned char buf[2];
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buf[0] = address & 0x7F;
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buf[1] = data;
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return spi_write_then_read(spi, buf, 2, NULL, 0);
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}
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static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
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{
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struct spi_device *spi = to_spi_device(dev);
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int err;
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unsigned char buf[8];
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buf[0] = DS1347_CLOCK_BURST | 0x80;
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err = spi_write_then_read(spi, buf, 1, buf, 8);
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if (err)
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return err;
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dt->tm_sec = bcd2bin(buf[0]);
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dt->tm_min = bcd2bin(buf[1]);
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dt->tm_hour = bcd2bin(buf[2] & 0x3F);
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dt->tm_mday = bcd2bin(buf[3]);
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dt->tm_mon = bcd2bin(buf[4]) - 1;
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dt->tm_wday = bcd2bin(buf[5]) - 1;
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dt->tm_year = bcd2bin(buf[6]) + 100;
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return rtc_valid_tm(dt);
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}
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static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
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{
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struct spi_device *spi = to_spi_device(dev);
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unsigned char buf[9];
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buf[0] = DS1347_CLOCK_BURST & 0x7F;
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buf[1] = bin2bcd(dt->tm_sec);
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buf[2] = bin2bcd(dt->tm_min);
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buf[3] = (bin2bcd(dt->tm_hour) & 0x3F);
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buf[4] = bin2bcd(dt->tm_mday);
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buf[5] = bin2bcd(dt->tm_mon + 1);
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buf[6] = bin2bcd(dt->tm_wday + 1);
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/* year in linux is from 1900 i.e in range of 100
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in rtc it is from 00 to 99 */
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dt->tm_year = dt->tm_year % 100;
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buf[7] = bin2bcd(dt->tm_year);
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buf[8] = bin2bcd(0x00);
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/* write the rtc settings */
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return spi_write_then_read(spi, buf, 9, NULL, 0);
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}
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static const struct rtc_class_ops ds1347_rtc_ops = {
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.read_time = ds1347_read_time,
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.set_time = ds1347_set_time,
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};
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static int ds1347_probe(struct spi_device *spi)
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{
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struct rtc_device *rtc;
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unsigned char data;
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int res;
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/* spi setup with ds1347 in mode 3 and bits per word as 8 */
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spi->mode = SPI_MODE_3;
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spi->bits_per_word = 8;
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spi_setup(spi);
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/* RTC Settings */
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res = ds1347_read_reg(&spi->dev, DS1347_SECONDS_REG, &data);
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if (res)
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return res;
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/* Disable the write protect of rtc */
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ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
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data = data & ~(1<<7);
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ds1347_write_reg(&spi->dev, DS1347_CONTROL_REG, data);
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/* Enable the oscillator , disable the oscillator stop flag,
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and glitch filter to reduce current consumption */
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ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
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data = data & 0x1B;
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ds1347_write_reg(&spi->dev, DS1347_STATUS_REG, data);
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/* display the settings */
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ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
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dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
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ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
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dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
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rtc = devm_rtc_device_register(&spi->dev, "ds1347",
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&ds1347_rtc_ops, THIS_MODULE);
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if (IS_ERR(rtc))
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return PTR_ERR(rtc);
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spi_set_drvdata(spi, rtc);
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return 0;
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}
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static struct spi_driver ds1347_driver = {
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.driver = {
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.name = "ds1347",
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},
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.probe = ds1347_probe,
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};
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module_spi_driver(ds1347_driver);
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MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
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MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
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MODULE_LICENSE("GPL v2");
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