linux-imx

/*

 * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC

 *

 * Copyright (C) 2008 Mercury IMC Ltd

 * Written by Mark Jackson <mpfj@mimc.co.uk>

 *

 * 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.

 *

 * NOTE: Currently this driver only supports the bare minimum for read

 * and write the RTC. The extra features provided by the chip family

 * (alarms, trickle charger, different control registers) are unavailable.

 */

​

#include <linux/init.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/rtc.h>

#include <linux/spi/spi.h>

#include <linux/bcd.h>

#include <linux/slab.h>

#include <linux/of.h>

​

#define DS1390_REG_100THS       0x00

#define DS1390_REG_SECONDS      0x01

#define DS1390_REG_MINUTES      0x02

#define DS1390_REG_HOURS        0x03

#define DS1390_REG_DAY          0x04

#define DS1390_REG_DATE         0x05

#define DS1390_REG_MONTH_CENT       0x06

#define DS1390_REG_YEAR         0x07

​

#define DS1390_REG_ALARM_100THS     0x08

#define DS1390_REG_ALARM_SECONDS    0x09

#define DS1390_REG_ALARM_MINUTES    0x0A

#define DS1390_REG_ALARM_HOURS      0x0B

#define DS1390_REG_ALARM_DAY_DATE   0x0C

​

#define DS1390_REG_CONTROL      0x0D

#define DS1390_REG_STATUS       0x0E

#define DS1390_REG_TRICKLE      0x0F

​

#define DS1390_TRICKLE_CHARGER_ENABLE   0xA0

#define DS1390_TRICKLE_CHARGER_250_OHM  0x01

#define DS1390_TRICKLE_CHARGER_2K_OHM   0x02

#define DS1390_TRICKLE_CHARGER_4K_OHM   0x03

#define DS1390_TRICKLE_CHARGER_NO_DIODE 0x04

#define DS1390_TRICKLE_CHARGER_DIODE    0x08

​

struct ds1390 {

    struct rtc_device *rtc;

    u8 txrx_buf[9]; /* cmd + 8 registers */

};

​

static void ds1390_set_reg(struct device *dev, unsigned char address,

               unsigned char data)

{

    struct spi_device *spi = to_spi_device(dev);

    unsigned char buf[2];

​

    /* MSB must be '1' to write */

    buf[0] = address | 0x80;

    buf[1] = data;

​

    spi_write(spi, buf, 2);

}

​

static int ds1390_get_reg(struct device *dev, unsigned char address,

                unsigned char *data)

{

    struct spi_device *spi = to_spi_device(dev);

    struct ds1390 *chip = dev_get_drvdata(dev);

    int status;

​

    if (!data)

        return -EINVAL;

​

    /* Clear MSB to indicate read */

    chip->txrx_buf[0] = address & 0x7f;

    /* do the i/o */

    status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);

    if (status != 0)

        return status;

​

    *data = chip->txrx_buf[0];

​

    return 0;

}

​

static void ds1390_trickle_of_init(struct spi_device *spi)

{