path: root/drivers/rtc/rtc-m41t80.c

/*
 * I2C client/driver for the ST M41T80 family of i2c rtc chips.
 *
 * Author: Alexander Bigga <ab@mycable.de>
 *
 * Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
 *
 * 2006 (c) mycable GmbH
 *
 * 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/init.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/i2c.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#ifdef CONFIG_RTC_DRV_M41T80_WDT
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/ioctl.h>
#endif

#define M41T80_REG_SSEC	0
#define M41T80_REG_SEC	1
#define M41T80_REG_MIN	2
#define M41T80_REG_HOUR	3
#define M41T80_REG_WDAY	4
#define M41T80_REG_DAY	5
#define M41T80_REG_MON	6
#define M41T80_REG_YEAR	7
#define M41T80_REG_ALARM_MON	0xa
#define M41T80_REG_ALARM_DAY	0xb
#define M41T80_REG_ALARM_HOUR	0xc
#define M41T80_REG_ALARM_MIN	0xd
#define M41T80_REG_ALARM_SEC	0xe
#define M41T80_REG_FLAGS	0xf
#define M41T80_REG_SQW	0x13

#define M41T80_DATETIME_REG_SIZE	(M41T80_REG_YEAR + 1)
#define M41T80_ALARM_REG_SIZE	\
	(M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)

#define M41T80_SEC_ST		(1 << 7)	/* ST: Stop Bit */
#define M41T80_ALMON_AFE	(1 << 7)	/* AFE: AF Enable Bit */
#define M41T80_ALMON_SQWE	(1 << 6)	/* SQWE: SQW Enable Bit */
#define M41T80_ALHOUR_HT	(1 << 6)	/* HT: Halt Update Bit */
#define M41T80_FLAGS_AF		(1 << 6)	/* AF: Alarm Flag Bit */
#define M41T80_FLAGS_BATT_LOW	(1 << 4)	/* BL: Battery Low Bit */

#define M41T80_FEATURE_HT	(1 << 0)
#define M41T80_FEATURE_BL	(1 << 1)

#define DRV_VERSION "0.05"

struct m41t80_chip_info {
	const char *name;
	u8 features;
};

static const struct m41t80_chip_info m41t80_chip_info_tbl[] = {
	{
		.name		= "m41t80",
		.features	= 0,
	},
	{
		.name		= "m41t81",
		.features	= M41T80_FEATURE_HT,
	},
	{
		.name		= "m41t81s",
		.features	= M41T80_FEATURE_HT | M41T80_FEATURE_BL,
	},
	{
		.name		= "m41t82",
		.features	= M41T80_FEATURE_HT | M41T80_FEATURE_BL,
	},
	{
		.name		= "m41t83",
		.features	= M41T80_FEATURE_HT | M41T80_FEATURE_BL,
	},
	{
		.name		= "m41st84",
		.features	= M41T80_FEATURE_HT | M41T80_FEATURE_BL,
	},
	{
		.name		= "m41st85",
		.features	= M41T80_FEATURE_HT | M41T80_FEATURE_BL,
	},
	{
		.name		= "m41st87",
		.features	= M41T80_FEATURE_HT | M41T80_FEATURE_BL,
	},
};

struct m41t80_data {
	const struct m41t80_chip_info *chip;
	struct rtc_device *rtc;
};

static int m41t80_get_datetime(struct i2c_client *client,
			       struct rtc_time *tm)
{
	u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
	struct i2c_msg msgs[] = {
		{
			.addr	= client->addr,
			.flags	= 0,
			.len	= 1,
			.buf	= dt_addr,
		},
		{
			.addr	= client->addr,
			.flags	= I2C_M_RD,
			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
			.buf	= buf + M41T80_REG_SEC,
		},
	};

	if (i2c_transfer(client->adapter, msgs, 2) < 0) {
		dev_err(&client->dev, "read error\n");
		return -EIO;
	}

	tm->tm_sec = BCD2BIN(buf[M41T80_REG_SEC] & 0x7f);
	tm->tm_min = BCD2BIN(buf[M41T80_REG_MIN] & 0x7f);
	tm->tm_hour = BCD2BIN(buf[M41T80_REG_HOUR] & 0x3f);
	tm->tm_mday = BCD2BIN(buf[M41T80_REG_DAY] & 0x3f);
	tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
	tm->tm_mon = BCD2BIN(buf[M41T80_REG_MON] & 0x1f) - 1;

	/* assume 20YY not 19YY, and ignore the Century Bit */
	tm->tm_year = BCD2BIN(buf[M41T80_REG_YEAR]) + 100;
	return 0;
}

/* Sets the given date and time to the real time clock. */
static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
	u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
	u8 *buf = &wbuf[1];
	u8 dt_addr[1] = { M41T80_REG_SEC };
	struct i2c_msg msgs_in[] = {
		{
			.addr	= client->addr,
			.flags	= 0,
			.len	= 1,
			.buf	= dt_addr,
		},
		{
			.addr	= client->addr,
			.flags	= I2C_M_RD,
			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
			.buf	= buf + M41T80_REG_SEC,
		},
	};
	struct i2c_msg msgs[] = {
		{
			.addr	= client->addr,
			.flags	= 0,
			.len	= 1 + M41T80_DATETIME_REG_SIZE,
			.buf	= wbuf,
		 },
	};

	/* Read current reg values into buf[1..7] */
	if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
		dev_err(&client->dev, "read error\n");
		return -EIO;
	}

	wbuf[0] = 0; /* offset into rtc's regs */
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