linux-imx

/*

 * Dallas DS1302 RTC Support

 *

 *  Copyright (C) 2002 David McCullough

 *  Copyright (C) 2003 - 2007 Paul Mundt

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License version 2. See the file "COPYING" in the main directory of

 * this archive for more details.

 */

​

#include <linux/bcd.h>

#include <linux/init.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/rtc.h>

#include <linux/spi/spi.h>

​

#define DRV_NAME    "rtc-ds1302"

​

#define RTC_CMD_READ    0x81        /* Read command */

#define RTC_CMD_WRITE   0x80        /* Write command */

​

#define RTC_CMD_WRITE_ENABLE    0x00        /* Write enable */

#define RTC_CMD_WRITE_DISABLE   0x80        /* Write disable */

​

#define RTC_ADDR_RAM0   0x20        /* Address of RAM0 */

#define RTC_ADDR_TCR    0x08        /* Address of trickle charge register */

#define RTC_CLCK_BURST  0x1F        /* Address of clock burst */

#define RTC_CLCK_LEN    0x08        /* Size of clock burst */

#define RTC_ADDR_CTRL   0x07        /* Address of control register */

#define RTC_ADDR_YEAR   0x06        /* Address of year register */

#define RTC_ADDR_DAY    0x05        /* Address of day of week register */

#define RTC_ADDR_MON    0x04        /* Address of month register */

#define RTC_ADDR_DATE   0x03        /* Address of day of month register */

#define RTC_ADDR_HOUR   0x02        /* Address of hour register */

#define RTC_ADDR_MIN    0x01        /* Address of minute register */

#define RTC_ADDR_SEC    0x00        /* Address of second register */

​

static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *time)

{

    struct spi_device   *spi = dev_get_drvdata(dev);

    u8      buf[1 + RTC_CLCK_LEN];

    u8      *bp;

    int     status;

​

    /* Enable writing */

    bp = buf;

    *bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;

    *bp++ = RTC_CMD_WRITE_ENABLE;

​

    status = spi_write_then_read(spi, buf, 2,

            NULL, 0);

    if (status)

        return status;

​

    /* Write registers starting at the first time/date address. */

    bp = buf;

    *bp++ = RTC_CLCK_BURST << 1 | RTC_CMD_WRITE;

​

    *bp++ = bin2bcd(time->tm_sec);

    *bp++ = bin2bcd(time->tm_min);

    *bp++ = bin2bcd(time->tm_hour);

    *bp++ = bin2bcd(time->tm_mday);

    *bp++ = bin2bcd(time->tm_mon + 1);

    *bp++ = time->tm_wday + 1;

    *bp++ = bin2bcd(time->tm_year % 100);

    *bp++ = RTC_CMD_WRITE_DISABLE;

​

    /* use write-then-read since dma from stack is nonportable */

    return spi_write_then_read(spi, buf, sizeof(buf),

            NULL, 0);

}

​

static int ds1302_rtc_get_time(struct device *dev, struct rtc_time *time)

{

    struct spi_device   *spi = dev_get_drvdata(dev);

    u8      addr = RTC_CLCK_BURST << 1 | RTC_CMD_READ;

    u8      buf[RTC_CLCK_LEN - 1];

    int     status;

​

    /* Use write-then-read to get all the date/time registers

     * since dma from stack is nonportable

     */

    status = spi_write_then_read(spi, &addr, sizeof(addr),

            buf, sizeof(buf));

    if (status < 0)

        return status;

​

    /* Decode the registers */