path: root/drivers/rtc/rtc-ds1307.c

/*
 * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
 *
 *  Copyright (C) 2005 James Chapman (ds1337 core)
 *  Copyright (C) 2006 David Brownell
 *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
 *  Copyright (C) 2012 Bertrand Achard (nvram access fixes)
 *
 * 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/i2c.h>
#include <linux/string.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/rtc/ds1307.h>

/*
 * We can't determine type by probing, but if we expect pre-Linux code
 * to have set the chip up as a clock (turning on the oscillator and
 * setting the date and time), Linux can ignore the non-clock features.
 * That's a natural job for a factory or repair bench.
 */
enum ds_type {
	ds_1307,
	ds_1337,
	ds_1338,
	ds_1339,
	ds_1340,
	ds_1388,
	ds_3231,
	m41t00,
	mcp794xx,
	rx_8025,
	last_ds_type /* always last */
	/* rs5c372 too?  different address... */
};


/* RTC registers don't differ much, except for the century flag */
#define DS1307_REG_SECS		0x00	/* 00-59 */
#	define DS1307_BIT_CH		0x80
#	define DS1340_BIT_nEOSC		0x80
#	define MCP794XX_BIT_ST		0x80
#define DS1307_REG_MIN		0x01	/* 00-59 */
#define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
#	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
#	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
#	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
#	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
#define DS1307_REG_WDAY		0x03	/* 01-07 */
#	define MCP794XX_BIT_VBATEN	0x08
#define DS1307_REG_MDAY		0x04	/* 01-31 */
#define DS1307_REG_MONTH	0x05	/* 01-12 */
#	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
#define DS1307_REG_YEAR		0x06	/* 00-99 */

/*
 * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
 * start at 7, and they differ a LOT. Only control and status matter for
 * basic RTC date and time functionality; be careful using them.
 */
#define DS1307_REG_CONTROL	0x07		/* or ds1338 */
#	define DS1307_BIT_OUT		0x80
#	define DS1338_BIT_OSF		0x20
#	define DS1307_BIT_SQWE		0x10
#	define DS1307_BIT_RS1		0x02
#	define DS1307_BIT_RS0		0x01
#define DS1337_REG_CONTROL	0x0e
#	define DS1337_BIT_nEOSC		0x80
#	define DS1339_BIT_BBSQI		0x20
#	define DS3231_BIT_BBSQW		0x40 /* same as BBSQI */
#	define DS1337_BIT_RS2		0x10
#	define DS1337_BIT_RS1		0x08
#	define DS1337_BIT_INTCN		0x04
#	define DS1337_BIT_A2IE		0x02
#	define DS1337_BIT_A1IE		0x01
#define DS1340_REG_CONTROL	0x07
#	define DS1340_BIT_OUT		0x80
#	define DS1340_BIT_FT		0x40
#	define DS1340_BIT_CALIB_SIGN	0x20
#	define DS1340_M_CALIBRATION	0x1f
#define DS1340_REG_FLAG		0x09
#	define DS1340_BIT_OSF		0x80
#define DS1337_REG_STATUS	0x0f
#	define DS1337_BIT_OSF		0x80
#	define DS1337_BIT_A2I		0x02
#	define DS1337_BIT_A1I		0x01
#define DS1339_REG_ALARM1_SECS	0x07

#define DS13XX_TRICKLE_CHARGER_MAGIC	0xa0

#define RX8025_REG_CTRL1	0x0e
#	define RX8025_BIT_2412		0x20
#define RX8025_REG_CTRL2	0x0f
#	define RX8025_BIT_PON		0x10
#	define RX8025_BIT_VDET		0x40
#	define RX8025_BIT_XST		0x20


struct ds1307 {
	u8			offset; /* register's offset */
	u8			regs[11];
	u16			nvram_offset;
	struct bin_attribute	*nvram;
	enum ds_type		type;
	unsigned long		flags;
#define HAS_NVRAM	0		/* bit 0 == sysfs file active */
#define HAS_ALARM	1		/* bit 1 == irq claimed */
	struct i2c_client	*client;
	struct rtc_device	*rtc;
	struct work_struct	work;
	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
			       u8 length, u8 *values);
	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
				u8 length, const u8 *values);
};

struct chip_desc {
	unsigned		alarm:1;
	u16			nvram_offset;
	u16			nvram_size;
	u16			trickle_charger_reg;
	u8			trickle_charger_setup;
	u8			(*do_trickle_setup)(struct i2c_client *, uint32_t, bool);
};

static u8 do_trickle_setup_ds1339(struct i2c_client *,
				  uint32_t ohms, bool diode);

static struct chip_desc chips[last_ds_type] = {
	[ds_1307] = {
		.nvram_offset	= 8,
		.nvram_size	= 56,
	},
	[ds_1337] = {
		.alarm		= 1,
	},
	[ds_1338] = {
		.nvram_offset	= 8,
		.nvram_size	= 56,
	},
	[ds_1339] = {
		.alarm		= 1,
		.trickle_charger_reg = 0x10,
		.do_trickle_setup = &do_trickle_setup_ds1339,
	},
	[ds_1340] = {
		.trickle_charger_reg =