[PATCH] i2c: New Xicor X1205 RTC driver

Kernel driver x1205

===================

Supported chips:

  * Xicor X1205 RTC

    Prefix: 'x1205'

    Addresses scanned: none

    Datasheet: http://www.intersil.com/cda/deviceinfo/0,1477,X1205,00.html

Authors:

	Karen Spearel <kas11@tampabay.rr.com>,

	Alessandro Zummo <a.zummo@towertech.it>

Description

-----------

This module aims to provide complete access to the Xicor X1205 RTC.

Recently Xicor has merged with Intersil, but the chip is

still sold under the Xicor brand.

This chip is located at address 0x6f and uses a 2-byte register addressing.

Two bytes need to be written to read a single register, while most

other chips just require one and take the second one as the data

to be written. To prevent corrupting unknown chips, the user must

explicitely set the probe parameter.

example:

modprobe x1205 probe=0,0x6f

The module supports one more option, hctosys, which is used to set the

software clock from the x1205. On systems where the x1205 is the

only hardware rtc, this parameter could be used to achieve a correct

date/time earlier in the system boot sequence.

example:

modprobe x1205 probe=0,0x6f hctosys=1

	  This driver can also be built as a module.  If so, the module

	  will be called max6875.

config RTC_X1205_I2C

	tristate "Xicor X1205 RTC chip"

	depends on I2C && EXPERIMENTAL

	help

	  If you say yes here you get support for the Xicor X1205 RTC chip.

	  This driver can also be built as a module. If so, the module

	  will be called x1205.

endmenu

obj-$(CONFIG_SENSORS_RTC8564)	+= rtc8564.o

obj-$(CONFIG_ISP1301_OMAP)	+= isp1301_omap.o

obj-$(CONFIG_TPS65010)		+= tps65010.o

obj-$(CONFIG_RTC_X1205_I2C)	+= x1205.o

ifeq ($(CONFIG_I2C_DEBUG_CHIP),y)

EXTRA_CFLAGS += -DDEBUG

/*

 *  x1205.c - An i2c driver for the Xicor X1205 RTC

 *  Copyright 2004 Karen Spearel

 *  Copyright 2005 Alessandro Zummo

 *

 *  please send all reports to:

 *	kas11 at tampabay dot rr dot com

 *      a dot zummo at towertech dot it

 *

 *  based on the other drivers in this same directory.

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 */

#include <linux/module.h>

#include <linux/init.h>

#include <linux/slab.h>

#include <linux/i2c.h>

#include <linux/string.h>

#include <linux/bcd.h>

#include <linux/rtc.h>

#include <linux/list.h>

#include <linux/x1205.h>

#define DRV_VERSION "0.9.9"

/* Addresses to scan: none. This chip is located at

 * 0x6f and uses a two bytes register addressing.

 * Two bytes need to be written to read a single register,

 * while most other chips just require one and take the second

 * one as the data to be written. To prevent corrupting

 * unknown chips, the user must explicitely set the probe parameter.

 */

static unsigned short normal_i2c[] = { I2C_CLIENT_END };

/* Insmod parameters */

I2C_CLIENT_INSMOD;

I2C_CLIENT_MODULE_PARM(hctosys,

	"Set the system time from the hardware clock upon initialization");

/* offsets into CCR area */

#define CCR_SEC			0

#define CCR_MIN			1

#define CCR_HOUR		2

#define CCR_MDAY		3

#define CCR_MONTH		4

#define CCR_YEAR		5

#define CCR_WDAY		6

#define CCR_Y2K			7

#define X1205_REG_SR		0x3F	/* status register */

#define X1205_REG_Y2K		0x37

#define X1205_REG_DW		0x36

#define X1205_REG_YR		0x35

#define X1205_REG_MO		0x34

#define X1205_REG_DT		0x33

#define X1205_REG_HR		0x32

#define X1205_REG_MN		0x31

#define X1205_REG_SC		0x30

#define X1205_REG_DTR		0x13

#define X1205_REG_ATR		0x12

#define X1205_REG_INT		0x11

#define X1205_REG_0		0x10

#define X1205_REG_Y2K1		0x0F

#define X1205_REG_DWA1		0x0E

#define X1205_REG_YRA1		0x0D

#define X1205_REG_MOA1		0x0C

#define X1205_REG_DTA1		0x0B

#define X1205_REG_HRA1		0x0A

#define X1205_REG_MNA1		0x09

#define X1205_REG_SCA1		0x08

#define X1205_REG_Y2K0		0x07

#define X1205_REG_DWA0		0x06

#define X1205_REG_YRA0		0x05

#define X1205_REG_MOA0		0x04

#define X1205_REG_DTA0		0x03

#define X1205_REG_HRA0		0x02

#define X1205_REG_MNA0		0x01

#define X1205_REG_SCA0		0x00

#define X1205_CCR_BASE		0x30	/* Base address of CCR */

#define X1205_ALM0_BASE		0x00	/* Base address of ALARM0 */

#define X1205_SR_RTCF		0x01	/* Clock failure */

#define X1205_SR_WEL		0x02	/* Write Enable Latch */

#define X1205_SR_RWEL		0x04	/* Register Write Enable */

#define X1205_DTR_DTR0		0x01

#define X1205_DTR_DTR1		0x02

#define X1205_DTR_DTR2		0x04

#define X1205_HR_MIL		0x80	/* Set in ccr.hour for 24 hr mode */

/* Prototypes */

static int x1205_attach(struct i2c_adapter *adapter);

static int x1205_detach(struct i2c_client *client);

static int x1205_probe(struct i2c_adapter *adapter, int address, int kind);

static int x1205_command(struct i2c_client *client, unsigned int cmd,

	void *arg);

static struct i2c_driver x1205_driver = {

	.owner		= THIS_MODULE,

	.name		= "x1205",

	.flags		= I2C_DF_NOTIFY,

	.attach_adapter = &x1205_attach,

	.detach_client	= &x1205_detach,

};

struct x1205_data {

	struct i2c_client client;

	struct list_head list;

	unsigned int epoch;

};

static const unsigned char days_in_mo[] =

	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

static LIST_HEAD(x1205_clients);

/* Workaround until the I2C subsytem will allow to send

 * commands to a specific client. This function will send the command

 * to the first client.

 */

int x1205_do_command(unsigned int cmd, void *arg)

{

	struct list_head *walk;

	struct list_head *tmp;

	struct x1205_data *data;

	list_for_each_safe(walk, tmp, &x1205_clients) {

		data = list_entry(walk, struct x1205_data, list);

		return x1205_command(&data->client, cmd, arg);

	}

	return -ENODEV;

}

#define is_leap(year) \

	((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))

/* make sure the rtc_time values are in bounds */

static int x1205_validate_tm(struct rtc_time *tm)

{

	int year = tm->tm_year + 1900;

	if ((tm->tm_year < 70) || (tm->tm_year > 255))

		return -EINVAL;

	if ((tm->tm_mon > 11) || (tm->tm_mday == 0))

		return -EINVAL;

	if (tm->tm_mday > days_in_mo[tm->tm_mon]

		+ ((tm->tm_mon == 1) && is_leap(year)))

		return -EINVAL;

	if ((tm->tm_hour >= 24) || (tm->tm_min >= 60) || (tm->tm_sec >= 60))

		return -EINVAL;

	return 0;

}

/*

 * In the routines that deal directly with the x1205 hardware, we use

 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch

 * Epoch is initialized as 2000. Time is set to UTC.

 */

static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,

				u8 reg_base)

{

	unsigned char dt_addr[2] = { 0, reg_base };

	static unsigned char sr_addr[2] = { 0, X1205_REG_SR };

	unsigned char buf[8], sr;

	struct i2c_msg msgs[] = {

		{ client->addr, 0, 2, sr_addr },	/* setup read ptr */

		{ client->addr, I2C_M_RD, 1, &sr }, 	/* read status */

		{ client->addr, 0, 2, dt_addr },	/* setup read ptr */

		{ client->addr, I2C_M_RD, 8, buf },	/* read date */

	};

	struct x1205_data *data = i2c_get_clientdata(client);

	/* read status register */

	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {

		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);

		return -EIO;

	}

	/* check for battery failure */

	if (sr & X1205_SR_RTCF) {

		dev_warn(&client->dev,

			"Clock had a power failure, you must set the date.\n");

		return -EINVAL;

	}

	/* read date registers */

	if ((i2c_transfer(client->adapter, &msgs[2], 2)) != 2) {

		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);

		return -EIO;

	}

	dev_dbg(&client->dev,

		"%s: raw read data - sec=%02x, min=%02x, hr=%02x, "

		"mday=%02x, mon=%02x, year=%02x, wday=%02x, y2k=%02x\n",

		__FUNCTION__,

		buf[0], buf[1], buf[2], buf[3],

		buf[4], buf[5], buf[6], buf[7]);

	tm->tm_sec = BCD2BIN(buf[CCR_SEC]);

	tm->tm_min = BCD2BIN(buf[CCR_MIN]);

	tm->tm_hour = BCD2BIN(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */

	tm->tm_mday = BCD2BIN(buf[CCR_MDAY]);

	tm->tm_mon = BCD2BIN(buf[CCR_MONTH]);

	data->epoch = BCD2BIN(buf[CCR_Y2K]) * 100;

	tm->tm_year = BCD2BIN(buf[CCR_YEAR]) + data->epoch - 1900;

	tm->tm_wday = buf[CCR_WDAY];

	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "

		"mday=%d, mon=%d, year=%d, wday=%d\n",

		__FUNCTION__,

		tm->tm_sec, tm->tm_min, tm->tm_hour,

		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	return 0;

}

static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,

				int datetoo, u8 reg_base)

{

	int i, err, xfer;

	unsigned char buf[8];

	static const unsigned char wel[3] = { 0, X1205_REG_SR,

						X1205_SR_WEL };

	static const unsigned char rwel[3] = { 0, X1205_REG_SR,

						X1205_SR_WEL | X1205_SR_RWEL };

	static const unsigned char diswe[3] = { 0, X1205_REG_SR, 0 };

	struct x1205_data *data = i2c_get_clientdata(client);

	/* check if all values in the tm struct are correct */

	if ((err = x1205_validate_tm(tm)) < 0)

		return err;

	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "

		"mday=%d, mon=%d, year=%d, wday=%d\n",

		__FUNCTION__,

		tm->tm_sec, tm->tm_min, tm->tm_hour,

		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	buf[CCR_SEC] = BIN2BCD(tm->tm_sec);

	buf[CCR_MIN] = BIN2BCD(tm->tm_min);

	/* set hour and 24hr bit */

	buf[CCR_HOUR] = BIN2BCD(tm->tm_hour) | X1205_HR_MIL;

	/* should we also set the date? */

	if (datetoo) {

		buf[CCR_MDAY] = BIN2BCD(tm->tm_mday);

		/* month, 0 - 11 */

		buf[CCR_MONTH] = BIN2BCD(tm->tm_mon);

		/* year, since 1900 */

		buf[CCR_YEAR] = BIN2BCD(tm->tm_year + 1900 - data->epoch);

		buf[CCR_WDAY] = tm->tm_wday & 0x07;

		buf[CCR_Y2K] = BIN2BCD(data->epoch / 100);

	}

	/* this sequence is required to unlock the chip */

	xfer = i2c_master_send(client, wel, 3);

	if (xfer != 3) {

		dev_err(&client->dev, "%s: wel - %d\n", __FUNCTION__, xfer);

		return -EIO;

	}

	xfer = i2c_master_send(client, rwel, 3);

	if (xfer != 3) {

		dev_err(&client->dev, "%s: rwel - %d\n", __FUNCTION__, xfer);

		return -EIO;

	}

	/* write register's data */

	for (i = 0; i < (datetoo ? 8 : 3); i++) {

		unsigned char rdata[3] = { 0, reg_base + i, buf[i] };

		xfer = i2c_master_send(client, rdata, 3);

		if (xfer != 3) {

			dev_err(&client->dev,

				"%s: xfer=%d addr=%02x, data=%02x\n",

				__FUNCTION__,

				 xfer, rdata[1], rdata[2]);

			return -EIO;

		}

	};

	/* disable further writes */

	xfer = i2c_master_send(client, diswe, 3);

	if (xfer != 3) {

		dev_err(&client->dev, "%s: diswe - %d\n", __FUNCTION__, xfer);

		return -EIO;

	}

	return 0;

}

static int x1205_get_dtrim(struct i2c_client *client, int *trim)

{

	unsigned char dtr;

	static unsigned char dtr_addr[2] = { 0, X1205_REG_DTR };

	struct i2c_msg msgs[] = {

		{ client->addr, 0, 2, dtr_addr },	/* setup read ptr */

		{ client->addr, I2C_M_RD, 1, &dtr }, 	/* read dtr */

	};

	/* read dtr register */

	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {

		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);

		return -EIO;

	}

	dev_dbg(&client->dev, "%s: raw dtr=%x\n", __FUNCTION__, dtr);

	*trim = 0;

	if (dtr & X1205_DTR_DTR0)

		*trim += 20;

	if (dtr & X1205_DTR_DTR1)

		*trim += 10;

	if (dtr & X1205_DTR_DTR2)

		*trim = -*trim;

	return 0;

}

static int x1205_get_atrim(struct i2c_client *client, int *trim)

{

	s8 atr;

	static unsigned char atr_addr[2] = { 0, X1205_REG_ATR };

	struct i2c_msg msgs[] = {

		{ client->addr, 0, 2, atr_addr },	/* setup read ptr */

		{ client->addr, I2C_M_RD, 1, &atr }, 	/* read atr */

	};

	/* read atr register */

	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {

		dev_err(&client->dev, "%s: read error\n", __FUNCTION__);

		return -EIO;

	}

	dev_dbg(&client->dev, "%s: raw atr=%x\n", __FUNCTION__, atr);

	/* atr is a two's complement value on 6 bits,

	 * perform sign extension. The formula is

	 * Catr = (atr * 0.25pF) + 11.00pF.

	 */

	if (atr & 0x20)

		atr |= 0xC0;

	dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __FUNCTION__, atr, atr);

	*trim = (atr * 250) + 11000;

	dev_dbg(&client->dev, "%s: real=%d\n", __FUNCTION__, *trim);

	return 0;

}

static int x1205_hctosys(struct i2c_client *client)

{

	int err;

	struct rtc_time tm;

	struct timespec tv;

	err = x1205_command(client, X1205_CMD_GETDATETIME, &tm);

	if (err) {

		dev_err(&client->dev,

			"Unable to set the system clock\n");

		return err;

	}

	/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary

	 * whether it stores the most close value or the value with partial

	 * seconds truncated. However, it is important that we use it to store

	 * the truncated value. This is because otherwise it is necessary,

	 * in an rtc sync function, to read both xtime.tv_sec and

	 * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read

	 * of >32bits is not possible. So storing the most close value would

	 * slow down the sync API. So here we have the truncated value and

	 * the best guess is to add 0.5s.

	 */

	tv.tv_nsec = NSEC_PER_SEC >> 1;

	/* WARNING: this is not the C library 'mktime' call, it is a built in

	 * inline function from include/linux/time.h.  It expects (requires)

	 * the month to be in the range 1-12

	 */

	tv.tv_sec  = mktime(tm.tm_year + 1900, tm.tm_mon + 1,

				tm.tm_mday, tm.tm_hour,

				tm.tm_min, tm.tm_sec);

	do_settimeofday(&tv);

	dev_info(&client->dev,

		"setting the system clock to %d-%d-%d %d:%d:%d\n",

		tm.tm_year + 1900, tm.tm_mon + 1,

		tm.tm_mday, tm.tm_hour, tm.tm_min,

		tm.tm_sec);

	return 0;

}

struct x1205_limit

{

	unsigned char reg;

	unsigned char mask;

	unsigned char min;

	unsigned char max;

};

static int x1205_validate_client(struct i2c_client *client)

{

	int i, xfer;

	/* Probe array. We will read the register at the specified

	 * address and check if the given bits are zero.

	 */

	static const unsigned char probe_zero_pattern[] = {

		/* register, mask */

		X1205_REG_SR,	0x18,

		X1205_REG_DTR,	0xF8,

		X1205_REG_ATR,	0xC0,

		X1205_REG_INT,	0x18,

		X1205_REG_0,	0xFF,

	};

	static const struct x1205_limit probe_limits_pattern[] = {

		/* register, mask, min, max */

		{ X1205_REG_Y2K,	0xFF,	19,	20	},

		{ X1205_REG_DW,		0xFF,	0,	6	},

		{ X1205_REG_YR,		0xFF,	0,	99	},

		{ X1205_REG_MO,		0xFF,	0,	12	},

		{ X1205_REG_DT,		0xFF,	0,	31	},

		{ X1205_REG_HR,		0x7F,	0,	23	},

		{ X1205_REG_MN,		0xFF,	0,	59	},

		{ X1205_REG_SC,		0xFF,	0,	59	},

		{ X1205_REG_Y2K1,	0xFF,	19,	20	},

		{ X1205_REG_Y2K0,	0xFF,	19,	20	},

	};

	/* check that registers have bits a 0 where expected */

	for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {

		unsigned char buf;

		unsigned char addr[2] = { 0, probe_zero_pattern[i] };

		struct i2c_msg msgs[2] = {

			{ client->addr, 0, 2, addr },

			{ client->addr, I2C_M_RD, 1, &buf },

		};

		xfer = i2c_transfer(client->adapter, msgs, 2);

		if (xfer != 2) {

			dev_err(&client->adapter->dev,

				"%s: could not read register %x\n",

				__FUNCTION__, addr[1]);

			return -EIO;

		}

		if ((buf & probe_zero_pattern[i+1]) != 0) {

			dev_err(&client->adapter->dev,

				"%s: register=%02x, zero pattern=%d, value=%x\n",

				__FUNCTION__, addr[1], i, buf);

			return -ENODEV;

		}

	}

	/* check limits (only registers with bcd values) */

	for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {

		unsigned char reg, value;

		unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };

		struct i2c_msg msgs[2] = {

			{ client->addr, 0, 2, addr },

			{ client->addr, I2C_M_RD, 1, &reg },

		};

		xfer = i2c_transfer(client->adapter, msgs, 2);

		if (xfer != 2) {

			dev_err(&client->adapter->dev,

				"%s: could not read register %x\n",

				__FUNCTION__, addr[1]);

			return -EIO;

		}

		value = BCD2BIN(reg & probe_limits_pattern[i].mask);

		if (value > probe_limits_pattern[i].max ||

			value < probe_limits_pattern[i].min) {

			dev_dbg(&client->adapter->dev,

				"%s: register=%x, lim pattern=%d, value=%d\n",

				__FUNCTION__, addr[1], i, value);

			return -ENODEV;

		}

	}

	return 0;

}

static int x1205_attach(struct i2c_adapter *adapter)

{

	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);

	return i2c_probe(adapter, &addr_data, x1205_probe);

}

int x1205_direct_attach(int adapter_id,

	struct i2c_client_address_data *address_data)

{

	int err;

	struct i2c_adapter *adapter = i2c_get_adapter(adapter_id);

	if (adapter) {

		err = i2c_probe(adapter,

			address_data, x1205_probe);

		i2c_put_adapter(adapter);

		return err;

	}

	return -ENODEV;

}

static int x1205_probe(struct i2c_adapter *adapter, int address, int kind)

{

	struct i2c_client *client;

	struct x1205_data *data;

	int err = 0;

	dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);

	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {

		err = -ENODEV;

		goto exit;

	}

	if (!(data = kzalloc(sizeof(struct x1205_data), GFP_KERNEL))) {

		err = -ENOMEM;

		goto exit;

	}

	/* Initialize our structures */

	data->epoch = 2000;

	client = &data->client;

	client->addr = address;

	client->driver = &x1205_driver;

	client->adapter	= adapter;

	strlcpy(client->name, "x1205", I2C_NAME_SIZE);

	i2c_set_clientdata(client, data);

	/* Verify the chip is really an X1205 */

	if (kind < 0) {

		if (x1205_validate_client(client) < 0) {

			err = -ENODEV;

			goto exit_kfree;

		}

	}

	/* Inform the i2c layer */

	if ((err = i2c_attach_client(client)))

		goto exit_kfree;

	list_add(&data->list, &x1205_clients);

	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");

	/* If requested, set the system time */

	if (hctosys)

		x1205_hctosys(client);

	return 0;

exit_kfree:

	kfree(data);

exit:

	return err;

}

static int x1205_detach(struct i2c_client *client)

{

	int err;

	struct x1205_data *data = i2c_get_clientdata(client);

	dev_dbg(&client->dev, "%s\n", __FUNCTION__);

	if ((err = i2c_detach_client(client)))

		return err;

	list_del(&data->list);

	kfree(data);

	return 0;

}

static int x1205_command(struct i2c_client *client, unsigned int cmd,

	void *param)

{

	if (param == NULL)

		return -EINVAL;

	if (!capable(CAP_SYS_TIME))

		return -EACCES;

	dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);

	switch (cmd) {

	case X1205_CMD_GETDATETIME:

		return x1205_get_datetime(client, param, X1205_CCR_BASE);