linux-imx

/*

 * rtc-ds1305.c -- driver for DS1305 and DS1306 SPI RTC chips

 *

 * Copyright (C) 2008 David Brownell

 *

 * 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/kernel.h>

#include <linux/init.h>

#include <linux/bcd.h>

#include <linux/slab.h>

#include <linux/rtc.h>

#include <linux/workqueue.h>

​

#include <linux/spi/spi.h>

#include <linux/spi/ds1305.h>

#include <linux/module.h>

​

​

/*

 * Registers ... mask DS1305_WRITE into register address to write,

 * otherwise you're reading it.  All non-bitmask values are BCD.

 */

#define DS1305_WRITE        0x80

​

​

/* RTC date/time ... the main special cases are that we:

 *  - Need fancy "hours" encoding in 12hour mode

 *  - Don't rely on the "day-of-week" field (or tm_wday)

 *  - Are a 21st-century clock (2000 <= year < 2100)

 */

#define DS1305_RTC_LEN      7       /* bytes for RTC regs */

​

#define DS1305_SEC      0x00        /* register addresses */

#define DS1305_MIN      0x01

#define DS1305_HOUR     0x02

#   define DS1305_HR_12     0x40    /* set == 12 hr mode */

#   define DS1305_HR_PM     0x20    /* set == PM (12hr mode) */

#define DS1305_WDAY     0x03

#define DS1305_MDAY     0x04

#define DS1305_MON      0x05

#define DS1305_YEAR     0x06

​

​

/* The two alarms have only sec/min/hour/wday fields (ALM_LEN).

 * DS1305_ALM_DISABLE disables a match field (some combos are bad).

 *

 * NOTE that since we don't use WDAY, we limit ourselves to alarms

 * only one day into the future (vs potentially up to a week).

 *

 * NOTE ALSO that while we could generate once-a-second IRQs (UIE), we

 * don't currently support them.  We'd either need to do it only when

 * no alarm is pending (not the standard model), or to use the second

 * alarm (implying that this is a DS1305 not DS1306, *and* that either

 * it's wired up a second IRQ we know, or that INTCN is set)

 */

#define DS1305_ALM_LEN      4       /* bytes for ALM regs */

#define DS1305_ALM_DISABLE  0x80

​

#define DS1305_ALM0(r)      (0x07 + (r))    /* register addresses */