linux-imx

/*

 * Driver for ST M41T94 SPI RTC

 *

 * Copyright (C) 2008 Kim B. Heino

 *

 * 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/module.h>

#include <linux/kernel.h>

#include <linux/platform_device.h>

#include <linux/rtc.h>

#include <linux/spi/spi.h>

#include <linux/bcd.h>

​

#define M41T94_REG_SECONDS  0x01

#define M41T94_REG_MINUTES  0x02

#define M41T94_REG_HOURS    0x03

#define M41T94_REG_WDAY     0x04

#define M41T94_REG_DAY      0x05

#define M41T94_REG_MONTH    0x06

#define M41T94_REG_YEAR     0x07

#define M41T94_REG_HT       0x0c

​

#define M41T94_BIT_HALT     0x40

#define M41T94_BIT_STOP     0x80

#define M41T94_BIT_CB       0x40

#define M41T94_BIT_CEB      0x80

​

static int m41t94_set_time(struct device *dev, struct rtc_time *tm)

{

    struct spi_device *spi = to_spi_device(dev);

    u8 buf[8]; /* write cmd + 7 registers */

​

    dev_dbg(dev, "%s secs=%d, mins=%d, "

        "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",

        "write", tm->tm_sec, tm->tm_min,

        tm->tm_hour, tm->tm_mday,

        tm->tm_mon, tm->tm_year, tm->tm_wday);

​

    buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */

    buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);

    buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);

    buf[M41T94_REG_HOURS]   = bin2bcd(tm->tm_hour);

    buf[M41T94_REG_WDAY]    = bin2bcd(tm->tm_wday + 1);

    buf[M41T94_REG_DAY]     = bin2bcd(tm->tm_mday);

    buf[M41T94_REG_MONTH]   = bin2bcd(tm->tm_mon + 1);

​

    buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;

    if (tm->tm_year >= 100)

        buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;

    buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);

​

    return spi_write(spi, buf, 8);

}

​

static int m41t94_read_time(struct device *dev, struct rtc_time *tm)

{

    struct spi_device *spi = to_spi_device(dev);

    u8 buf[2];

    int ret, hour;