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Commit 8a2601f6 authored by Dale Farnsworth's avatar Dale Farnsworth Committed by Linus Torvalds
Browse files

rtc: update and use the MAX6900 century byte 



We now read and write the century byte in the max6900 chip.  We probably
don't need to do so on Linux-only system, but it's necessary when the chip
is shared by another OS that uses the century byte.

Signed-off-by: default avatarDale Farnsworth <dale@farnsworth.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 55ff1aba

drivers/rtc/rtc-max6900.c

+72 −24
Original line number Diff line number Diff line
@@ -31,17 +31,24 @@ 
#define MAX6900_REG_DW			5	/* day of week	 1-7  */

#define MAX6900_REG_YR			6	/* year		00-99 */

#define MAX6900_REG_CT			7	/* control */

#define MAX6900_REG_LEN			8

						/* 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_BURST_READ		0xbf

#define MAX6900_REG_BURST_WRITE		0xbe

#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 */
@@ -58,19 +65,32 @@ static int max6900_probe(struct i2c_adapter *adapter, int addr, int kind); 


static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf)

{

	u8 reg_addr[1] = { MAX6900_REG_BURST_READ };

	struct i2c_msg msgs[2] = {

	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_addr),

			.buf	= reg_addr

			.len	= sizeof(reg_burst_read),

			.buf	= reg_burst_read

		},

		{

			.addr	= client->addr,

			.flags	= I2C_M_RD,

			.len	= MAX6900_REG_LEN,

			.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;
@@ -86,33 +106,58 @@ static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf) 


static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf)

{

	u8 i2c_buf[MAX6900_REG_LEN + 1] = { MAX6900_REG_BURST_WRITE };

	struct i2c_msg msgs[1] = {

	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	= MAX6900_REG_LEN + 1,

			.buf	= i2c_buf

			.len	= sizeof(i2c_burst_buf),

			.buf	= i2c_burst_buf

		}

	};

	int rc;



	memcpy(&i2c_buf[1], buf, MAX6900_REG_LEN);

	/*

	 * 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);



	rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));

	if (rc != ARRAY_SIZE(msgs)) {

	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",

		__FUNCTION__);

	return -EIO;

}

	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);

	return 0;

}



static int max6900_i2c_validate_client(struct i2c_client *client)

{

	u8 regs[MAX6900_REG_LEN];

	u8 zero_mask[MAX6900_REG_LEN] = {

	u8 zero_mask[] = {

		0x80,	/* seconds */

		0x80,	/* minutes */

		0x40,	/* hours */
@@ -134,7 +179,7 @@ static int max6900_i2c_validate_client(struct i2c_client *client) 
	if (rc < 0)

		return rc;



	for (i = 0; i < MAX6900_REG_LEN; ++i) {

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

		if (regs[i] & zero_mask[i])

			return -ENODEV;

	}
@@ -156,7 +201,8 @@ static int max6900_i2c_read_time(struct i2c_client *client, struct rtc_time *tm) 
	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]) + 100;

	tm->tm_year = BCD2BIN(regs[MAX6900_REG_YR]) +

		      BCD2BIN(regs[MAX6900_REG_CENTURY]) * 100 - 1900;

	tm->tm_wday = BCD2BIN(regs[MAX6900_REG_DW]);



	return 0;
@@ -189,9 +235,11 @@ static int max6900_i2c_set_time(struct i2c_client *client, 
	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_YR] = BIN2BCD(tm->tm_year - 100);

	regs[MAX6900_REG_DW] = BIN2BCD(tm->tm_wday);

	regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;	/* set write protect */

	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)