linux-imx

/*

 * rtc class driver for the Maxim MAX6900 chip

 *

 * Author: Dale Farnsworth <dale@farnsworth.org>

 *

 * based on previously existing rtc class drivers

 *

 * 2007 (c) MontaVista, Software, Inc.  This file is licensed under

 * the terms of the GNU General Public License version 2.  This program

 * is licensed "as is" without any warranty of any kind, whether express

 * or implied.

 */

​

#include <linux/module.h>

#include <linux/i2c.h>

#include <linux/bcd.h>

#include <linux/rtc.h>

#include <linux/delay.h>

​

/*

 * register indices

 */

#define MAX6900_REG_SC          0   /* seconds      00-59 */

#define MAX6900_REG_MN          1   /* minutes      00-59 */

#define MAX6900_REG_HR          2   /* hours        00-23 */

#define MAX6900_REG_DT          3   /* day of month 00-31 */

#define MAX6900_REG_MO          4   /* month        01-12 */

#define MAX6900_REG_DW          5   /* day of week   1-7  */

#define MAX6900_REG_YR          6   /* year         00-99 */

#define MAX6900_REG_CT          7   /* control */

                        /* register 8 is undocumented */

#define MAX6900_REG_CENTURY     9   /* century */

#define MAX6900_REG_LEN         10

​

#define MAX6900_BURST_LEN       8   /* can burst r/w first 8 regs */

​

#define MAX6900_REG_CT_WP       (1 << 7)    /* Write Protect */

​

/*

 * register read/write commands

 */

#define MAX6900_REG_CONTROL_WRITE   0x8e

#define MAX6900_REG_CENTURY_WRITE   0x92

#define MAX6900_REG_CENTURY_READ    0x93

#define MAX6900_REG_RESERVED_READ   0x96

#define MAX6900_REG_BURST_WRITE     0xbe

#define MAX6900_REG_BURST_READ      0xbf

​

#define MAX6900_IDLE_TIME_AFTER_WRITE   3   /* specification says 2.5 mS */

​

static struct i2c_driver max6900_driver;

​

static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf)

{

    u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ };

    u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ };

    struct i2c_msg msgs[4] = {

        {

         .addr = client->addr,

         .flags = 0,    /* write */

         .len = sizeof(reg_burst_read),

         .buf = reg_burst_read}

        ,