239 lines
6.0 KiB
C
239 lines
6.0 KiB
C
/*
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* rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC
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*
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* Copyright (C) 2008 Mercury IMC Ltd
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* Written by Mark Jackson <mpfj@mimc.co.uk>
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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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* NOTE: Currently this driver only supports the bare minimum for read
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* and write the RTC. The extra features provided by the chip family
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* (alarms, trickle charger, different control registers) are unavailable.
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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/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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#include <linux/slab.h>
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#include <linux/of.h>
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#define DS1390_REG_100THS 0x00
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#define DS1390_REG_SECONDS 0x01
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#define DS1390_REG_MINUTES 0x02
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#define DS1390_REG_HOURS 0x03
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#define DS1390_REG_DAY 0x04
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#define DS1390_REG_DATE 0x05
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#define DS1390_REG_MONTH_CENT 0x06
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#define DS1390_REG_YEAR 0x07
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#define DS1390_REG_ALARM_100THS 0x08
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#define DS1390_REG_ALARM_SECONDS 0x09
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#define DS1390_REG_ALARM_MINUTES 0x0A
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#define DS1390_REG_ALARM_HOURS 0x0B
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#define DS1390_REG_ALARM_DAY_DATE 0x0C
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#define DS1390_REG_CONTROL 0x0D
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#define DS1390_REG_STATUS 0x0E
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#define DS1390_REG_TRICKLE 0x0F
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#define DS1390_TRICKLE_CHARGER_ENABLE 0xA0
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#define DS1390_TRICKLE_CHARGER_250_OHM 0x01
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#define DS1390_TRICKLE_CHARGER_2K_OHM 0x02
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#define DS1390_TRICKLE_CHARGER_4K_OHM 0x03
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#define DS1390_TRICKLE_CHARGER_NO_DIODE 0x04
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#define DS1390_TRICKLE_CHARGER_DIODE 0x08
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struct ds1390 {
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struct rtc_device *rtc;
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u8 txrx_buf[9]; /* cmd + 8 registers */
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};
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static void ds1390_set_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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/* MSB must be '1' to write */
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buf[0] = address | 0x80;
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buf[1] = data;
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spi_write(spi, buf, 2);
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}
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static int ds1390_get_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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struct ds1390 *chip = dev_get_drvdata(dev);
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int status;
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if (!data)
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return -EINVAL;
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/* Clear MSB to indicate read */
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chip->txrx_buf[0] = address & 0x7f;
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/* do the i/o */
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status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
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if (status != 0)
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return status;
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*data = chip->txrx_buf[0];
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return 0;
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}
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static void ds1390_trickle_of_init(struct spi_device *spi)
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{
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u32 ohms = 0;
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u8 value;
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if (of_property_read_u32(spi->dev.of_node, "trickle-resistor-ohms",
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&ohms))
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goto out;
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/* Enable charger */
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value = DS1390_TRICKLE_CHARGER_ENABLE;
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if (of_property_read_bool(spi->dev.of_node, "trickle-diode-disable"))
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value |= DS1390_TRICKLE_CHARGER_NO_DIODE;
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else
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value |= DS1390_TRICKLE_CHARGER_DIODE;
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/* Resistor select */
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switch (ohms) {
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case 250:
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value |= DS1390_TRICKLE_CHARGER_250_OHM;
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break;
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case 2000:
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value |= DS1390_TRICKLE_CHARGER_2K_OHM;
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break;
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case 4000:
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value |= DS1390_TRICKLE_CHARGER_4K_OHM;
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break;
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default:
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dev_warn(&spi->dev,
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"Unsupported ohm value %02ux in dt\n", ohms);
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return;
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}
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ds1390_set_reg(&spi->dev, DS1390_REG_TRICKLE, value);
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out:
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return;
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}
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static int ds1390_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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struct ds1390 *chip = dev_get_drvdata(dev);
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int status;
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/* build the message */
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chip->txrx_buf[0] = DS1390_REG_SECONDS;
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/* do the i/o */
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status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
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if (status != 0)
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return status;
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/* The chip sends data in this order:
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* Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
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dt->tm_sec = bcd2bin(chip->txrx_buf[0]);
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dt->tm_min = bcd2bin(chip->txrx_buf[1]);
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dt->tm_hour = bcd2bin(chip->txrx_buf[2]);
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dt->tm_wday = bcd2bin(chip->txrx_buf[3]);
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dt->tm_mday = bcd2bin(chip->txrx_buf[4]);
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/* mask off century bit */
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dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
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/* adjust for century bit */
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dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0);
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return rtc_valid_tm(dt);
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}
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static int ds1390_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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struct ds1390 *chip = dev_get_drvdata(dev);
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/* build the message */
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chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
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chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
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chip->txrx_buf[2] = bin2bcd(dt->tm_min);
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chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
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chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
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chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
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chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
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((dt->tm_year > 99) ? 0x80 : 0x00);
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chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);
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/* do the i/o */
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return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
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}
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static const struct rtc_class_ops ds1390_rtc_ops = {
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.read_time = ds1390_read_time,
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.set_time = ds1390_set_time,
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};
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static int ds1390_probe(struct spi_device *spi)
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{
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unsigned char tmp;
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struct ds1390 *chip;
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int res;
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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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chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL);
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if (!chip)
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return -ENOMEM;
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spi_set_drvdata(spi, chip);
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res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
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if (res != 0) {
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dev_err(&spi->dev, "unable to read device\n");
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return res;
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}
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if (spi->dev.of_node)
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ds1390_trickle_of_init(spi);
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chip->rtc = devm_rtc_device_register(&spi->dev, "ds1390",
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&ds1390_rtc_ops, THIS_MODULE);
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if (IS_ERR(chip->rtc)) {
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dev_err(&spi->dev, "unable to register device\n");
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res = PTR_ERR(chip->rtc);
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}
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return res;
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}
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static const struct of_device_id ds1390_of_match[] = {
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{ .compatible = "dallas,ds1390" },
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{}
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};
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MODULE_DEVICE_TABLE(of, ds1390_of_match);
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static struct spi_driver ds1390_driver = {
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.driver = {
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.name = "rtc-ds1390",
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.of_match_table = of_match_ptr(ds1390_of_match),
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},
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.probe = ds1390_probe,
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};
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module_spi_driver(ds1390_driver);
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MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver");
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MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("spi:rtc-ds1390");
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