drivers/rtc/rtc-max6900.c - kernel/quantenna - Git at Google

 /*
  * 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>

 #define DRV_VERSION "0.2"

 /*
  * 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}
 		,
 		{
 		 .addr = client->addr,
 		 .flags = I2C_M_RD,
 		 .len = MAX6900_BURST_LEN,
 		 .buf = buf}
 		,
 		{
 		 .addr = client->addr,
 		 .flags = 0,	/* write */
 		 .len = sizeof(reg_century_read),
 		 .buf = reg_century_read}
 		,
 		{
 		 .addr = client->addr,
 		 .flags = I2C_M_RD,
 		 .len = sizeof(buf[MAX6900_REG_CENTURY]),
 		 .buf = &buf[MAX6900_REG_CENTURY]
 		 }
 	};
 	int rc;

 	rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 	if (rc != ARRAY_SIZE(msgs)) {
 		dev_err(&client->dev, "%s: register read failed\n", __func__);
 		return -EIO;
 	}
 	return 0;
 }

 static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf)
 {
 	u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE };
 	struct i2c_msg century_msgs[1] = {
 		{
 		 .addr = client->addr,
 		 .flags = 0,	/* write */
 		 .len = sizeof(i2c_century_buf),
 		 .buf = i2c_century_buf}
 	};
 	u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE };
 	struct i2c_msg burst_msgs[1] = {
 		{
 		 .addr = client->addr,
 		 .flags = 0,	/* write */
 		 .len = sizeof(i2c_burst_buf),
 		 .buf = i2c_burst_buf}
 	};
 	int rc;

 	/*
 	 * We have to make separate calls to i2c_transfer because of
 	 * the need to delay after each write to the chip.  Also,
 	 * we write the century byte first, since we set the write-protect
 	 * bit as part of the burst write.
 	 */
 	i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];

 	rc = i2c_transfer(client->adapter, century_msgs,
 			  ARRAY_SIZE(century_msgs));
 	if (rc != ARRAY_SIZE(century_msgs))
 		goto write_failed;

 	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);

 	memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN);

 	rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs));
 	if (rc != ARRAY_SIZE(burst_msgs))
 		goto write_failed;
 	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);

 	return 0;

  write_failed:
 	dev_err(&client->dev, "%s: register write failed\n", __func__);
 	return -EIO;
 }

 static int max6900_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
 {
 	int rc;
 	u8 regs[MAX6900_REG_LEN];

 	rc = max6900_i2c_read_regs(client, regs);
 	if (rc < 0)
 		return rc;

 	tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]);
 	tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]);
 	tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f);
 	tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]);
 	tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1;
 	tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) +
 		      bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
 	tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]);

 	return rtc_valid_tm(tm);
 }

 static int max6900_i2c_clear_write_protect(struct i2c_client *client)
 {
 	return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0);
 }

 static int
 max6900_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
 {
 	u8 regs[MAX6900_REG_LEN];
 	int rc;

 	rc = max6900_i2c_clear_write_protect(client);
 	if (rc < 0)
 		return rc;

 	regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec);
 	regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min);
 	regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour);
 	regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday);
 	regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1);
 	regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday);
 	regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100);
 	regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
 	/* set write protect */
 	regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;

 	rc = max6900_i2c_write_regs(client, regs);
 	if (rc < 0)
 		return rc;

 	return 0;
 }

 static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	return max6900_i2c_read_time(to_i2c_client(dev), tm);
 }

 static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	return max6900_i2c_set_time(to_i2c_client(dev), tm);
 }

 static const struct rtc_class_ops max6900_rtc_ops = {
 	.read_time = max6900_rtc_read_time,
 	.set_time = max6900_rtc_set_time,
 };

 static int
 max6900_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
 	struct rtc_device *rtc;

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -ENODEV;

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

 	rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name,
 					&max6900_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);

 	i2c_set_clientdata(client, rtc);

 	return 0;
 }

 static struct i2c_device_id max6900_id[] = {
 	{ "max6900", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, max6900_id);

 static struct i2c_driver max6900_driver = {
 	.driver = {
 		   .name = "rtc-max6900",
 		   },
 	.probe = max6900_probe,
 	.id_table = max6900_id,
 };

 module_i2c_driver(max6900_driver);

 MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
 MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRV_VERSION);
	/*
	* 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>

	#define DRV_VERSION "0.2"

	/*
	* 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}
	,
	{
	.addr = client->addr,
	.flags = I2C_M_RD,
	.len = MAX6900_BURST_LEN,
	.buf = buf}
	,
	{
	.addr = client->addr,
	.flags = 0, /* write */
	.len = sizeof(reg_century_read),
	.buf = reg_century_read}
	,
	{
	.addr = client->addr,
	.flags = I2C_M_RD,
	.len = sizeof(buf[MAX6900_REG_CENTURY]),
	.buf = &buf[MAX6900_REG_CENTURY]
	}
	};
	int rc;

	rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	if (rc != ARRAY_SIZE(msgs)) {
	dev_err(&client->dev, "%s: register read failed\n", __func__);
	return -EIO;
	}
	return 0;
	}

	static int max6900_i2c_write_regs(struct i2c_client client, u8 const buf)
	{
	u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE };
	struct i2c_msg century_msgs[1] = {
	{
	.addr = client->addr,
	.flags = 0, /* write */
	.len = sizeof(i2c_century_buf),
	.buf = i2c_century_buf}
	};
	u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE };
	struct i2c_msg burst_msgs[1] = {
	{
	.addr = client->addr,
	.flags = 0, /* write */
	.len = sizeof(i2c_burst_buf),
	.buf = i2c_burst_buf}
	};
	int rc;

	/*
	* We have to make separate calls to i2c_transfer because of
	* the need to delay after each write to the chip. Also,
	* we write the century byte first, since we set the write-protect
	* bit as part of the burst write.
	*/
	i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];

	rc = i2c_transfer(client->adapter, century_msgs,
	ARRAY_SIZE(century_msgs));
	if (rc != ARRAY_SIZE(century_msgs))
	goto write_failed;

	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);

	memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN);

	rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs));
	if (rc != ARRAY_SIZE(burst_msgs))
	goto write_failed;
	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);

	return 0;

	write_failed:
	dev_err(&client->dev, "%s: register write failed\n", __func__);
	return -EIO;
	}

	static int max6900_i2c_read_time(struct i2c_client client, struct rtc_time tm)
	{
	int rc;
	u8 regs[MAX6900_REG_LEN];

	rc = max6900_i2c_read_regs(client, regs);
	if (rc < 0)
	return rc;

	tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]);
	tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]);
	tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f);
	tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]);
	tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1;
	tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) +
	bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
	tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]);

	return rtc_valid_tm(tm);
	}

	static int max6900_i2c_clear_write_protect(struct i2c_client *client)
	{
	return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0);
	}

	static int
	max6900_i2c_set_time(struct i2c_client client, struct rtc_time const tm)
	{
	u8 regs[MAX6900_REG_LEN];
	int rc;

	rc = max6900_i2c_clear_write_protect(client);
	if (rc < 0)
	return rc;

	regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec);
	regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min);
	regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour);
	regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday);
	regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1);
	regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday);
	regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100);
	regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
	/* set write protect */
	regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;

	rc = max6900_i2c_write_regs(client, regs);
	if (rc < 0)
	return rc;

	return 0;
	}

	static int max6900_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	return max6900_i2c_read_time(to_i2c_client(dev), tm);
	}

	static int max6900_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	return max6900_i2c_set_time(to_i2c_client(dev), tm);
	}

	static const struct rtc_class_ops max6900_rtc_ops = {
	.read_time = max6900_rtc_read_time,
	.set_time = max6900_rtc_set_time,
	};

	static int
	max6900_probe(struct i2c_client client, const struct i2c_device_id id)
	{
	struct rtc_device *rtc;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	return -ENODEV;

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

	rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name,
	&max6900_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
	return PTR_ERR(rtc);

	i2c_set_clientdata(client, rtc);

	return 0;
	}

	static struct i2c_device_id max6900_id[] = {
	{ "max6900", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, max6900_id);

	static struct i2c_driver max6900_driver = {
	.driver = {
	.name = "rtc-max6900",
	},
	.probe = max6900_probe,
	.id_table = max6900_id,
	};

	module_i2c_driver(max6900_driver);

	MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
	MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>");
	MODULE_LICENSE("GPL");
	MODULE_VERSION(DRV_VERSION);