[linux-2.6-block.git] / drivers / rtc / rtc-max6900.c

/*
 * 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>

/*
 * 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;

	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");
Commit	Line	Data
aa5bd7e9 DF	1	/*
	2	* rtc class driver for the Maxim MAX6900 chip
	3	*
	4	* Author: Dale Farnsworth <dale@farnsworth.org>
	5	*
	6	* based on previously existing rtc class drivers
	7	*
	8	* 2007 (c) MontaVista, Software, Inc. This file is licensed under
	9	* the terms of the GNU General Public License version 2. This program
	10	* is licensed "as is" without any warranty of any kind, whether express
	11	* or implied.
	12	*/
	13
	14	#include <linux/module.h>
	15	#include <linux/i2c.h>
	16	#include <linux/bcd.h>
	17	#include <linux/rtc.h>
	18	#include <linux/delay.h>
	19
aa5bd7e9 DF	20	/*
	21	* register indices
	22	*/
6fd5c03f AZ	23	#define MAX6900_REG_SC 0 /* seconds 00-59 */
	24	#define MAX6900_REG_MN 1 /* minutes 00-59 */
	25	#define MAX6900_REG_HR 2 /* hours 00-23 */
	26	#define MAX6900_REG_DT 3 /* day of month 00-31 */
	27	#define MAX6900_REG_MO 4 /* month 01-12 */
	28	#define MAX6900_REG_DW 5 /* day of week 1-7 */
	29	#define MAX6900_REG_YR 6 /* year 00-99 */
aa5bd7e9	30	#define MAX6900_REG_CT 7 /* control */
8a2601f6 DF	31	/* register 8 is undocumented */
	32	#define MAX6900_REG_CENTURY 9 /* century */
	33	#define MAX6900_REG_LEN 10
	34
	35	#define MAX6900_BURST_LEN 8 /* can burst r/w first 8 regs */
aa5bd7e9 DF	36
	37	#define MAX6900_REG_CT_WP (1 << 7) /* Write Protect */
	38
	39	/*
	40	* register read/write commands
	41	*/
	42	#define MAX6900_REG_CONTROL_WRITE 0x8e
8a2601f6 DF	43	#define MAX6900_REG_CENTURY_WRITE 0x92
8a2601f6 DF	44	#define MAX6900_REG_CENTURY_READ 0x93
aa5bd7e9	45	#define MAX6900_REG_RESERVED_READ 0x96
8a2601f6 DF	46	#define MAX6900_REG_BURST_WRITE 0xbe
8a2601f6 DF	47	#define MAX6900_REG_BURST_READ 0xbf
aa5bd7e9 DF	48
	49	#define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */
	50
6fd5c03f	51	static struct i2c_driver max6900_driver;
aa5bd7e9 DF	52
	53	static int max6900_i2c_read_regs(struct i2c_client client, u8 buf)
	54	{
8a2601f6 DF	55	u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ };
	56	u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ };
	57	struct i2c_msg msgs[4] = {
aa5bd7e9	58	{
6fd5c03f AZ	59	.addr = client->addr,
	60	.flags = 0, /* write */
	61	.len = sizeof(reg_burst_read),
	62	.buf = reg_burst_read}
	63	,
aa5bd7e9	64	{
6fd5c03f AZ	65	.addr = client->addr,
	66	.flags = I2C_M_RD,
	67	.len = MAX6900_BURST_LEN,
	68	.buf = buf}
	69	,
8a2601f6	70	{
6fd5c03f AZ	71	.addr = client->addr,
	72	.flags = 0, /* write */
	73	.len = sizeof(reg_century_read),
	74	.buf = reg_century_read}
	75	,
8a2601f6	76	{
6fd5c03f AZ	77	.addr = client->addr,
	78	.flags = I2C_M_RD,
	79	.len = sizeof(buf[MAX6900_REG_CENTURY]),
	80	.buf = &buf[MAX6900_REG_CENTURY]
	81	}
aa5bd7e9 DF	82	};
	83	int rc;
	84
	85	rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	86	if (rc != ARRAY_SIZE(msgs)) {
6fd5c03f	87	dev_err(&client->dev, "%s: register read failed\n", __func__);
aa5bd7e9 DF	88	return -EIO;
	89	}
	90	return 0;
	91	}
	92
	93	static int max6900_i2c_write_regs(struct i2c_client client, u8 const buf)
	94	{
8a2601f6 DF	95	u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE };
8a2601f6 DF	96	struct i2c_msg century_msgs[1] = {
aa5bd7e9	97	{
6fd5c03f AZ	98	.addr = client->addr,
	99	.flags = 0, /* write */
	100	.len = sizeof(i2c_century_buf),
	101	.buf = i2c_century_buf}
8a2601f6 DF	102	};
	103	u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE };
	104	struct i2c_msg burst_msgs[1] = {
	105	{
6fd5c03f AZ	106	.addr = client->addr,
	107	.flags = 0, /* write */
	108	.len = sizeof(i2c_burst_buf),
	109	.buf = i2c_burst_buf}
aa5bd7e9 DF	110	};
	111	int rc;
	112
8a2601f6 DF	113	/*
	114	* We have to make separate calls to i2c_transfer because of
	115	* the need to delay after each write to the chip. Also,
	116	* we write the century byte first, since we set the write-protect
	117	* bit as part of the burst write.
	118	*/
	119	i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];
6fd5c03f	120
8a2601f6 DF	121	rc = i2c_transfer(client->adapter, century_msgs,
	122	ARRAY_SIZE(century_msgs));
	123	if (rc != ARRAY_SIZE(century_msgs))
	124	goto write_failed;
6fd5c03f	125
8a2601f6	126	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
aa5bd7e9	127
8a2601f6 DF	128	memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN);
	129
	130	rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs));
	131	if (rc != ARRAY_SIZE(burst_msgs))
	132	goto write_failed;
aa5bd7e9	133	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
8a2601f6	134
aa5bd7e9	135	return 0;
8a2601f6	136
6fd5c03f AZ	137	write_failed:
6fd5c03f AZ	138	dev_err(&client->dev, "%s: register write failed\n", __func__);
8a2601f6	139	return -EIO;
aa5bd7e9 DF	140	}
aa5bd7e9 DF	141
aa5bd7e9 DF	142	static int max6900_i2c_read_time(struct i2c_client client, struct rtc_time tm)
	143	{
	144	int rc;
	145	u8 regs[MAX6900_REG_LEN];
	146
	147	rc = max6900_i2c_read_regs(client, regs);
	148	if (rc < 0)
	149	return rc;
	150
fe20ba70 AB	151	tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]);
	152	tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]);
	153	tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f);
	154	tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]);
	155	tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1;
	156	tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) +
	157	bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
	158	tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]);
aa5bd7e9	159
c814dc13	160	return rtc_valid_tm(tm);
aa5bd7e9 DF	161	}
	162
	163	static int max6900_i2c_clear_write_protect(struct i2c_client *client)
	164	{
f16189ac	165	return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0);
aa5bd7e9 DF	166	}
aa5bd7e9 DF	167
6fd5c03f AZ	168	static int
6fd5c03f AZ	169	max6900_i2c_set_time(struct i2c_client client, struct rtc_time const tm)
aa5bd7e9 DF	170	{
	171	u8 regs[MAX6900_REG_LEN];
	172	int rc;
	173
	174	rc = max6900_i2c_clear_write_protect(client);
	175	if (rc < 0)
	176	return rc;
	177
fe20ba70 AB	178	regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec);
	179	regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min);
	180	regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour);
	181	regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday);
	182	regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1);
	183	regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday);
	184	regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100);
	185	regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
8a2601f6 DF	186	/* set write protect */
8a2601f6 DF	187	regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;
aa5bd7e9 DF	188
	189	rc = max6900_i2c_write_regs(client, regs);
	190	if (rc < 0)
	191	return rc;
	192
	193	return 0;
	194	}
	195
	196	static int max6900_rtc_read_time(struct device dev, struct rtc_time tm)
	197	{
	198	return max6900_i2c_read_time(to_i2c_client(dev), tm);
	199	}
	200
	201	static int max6900_rtc_set_time(struct device dev, struct rtc_time tm)
	202	{
	203	return max6900_i2c_set_time(to_i2c_client(dev), tm);
	204	}
	205
aa5bd7e9	206	static const struct rtc_class_ops max6900_rtc_ops = {
6fd5c03f AZ	207	.read_time = max6900_rtc_read_time,
6fd5c03f AZ	208	.set_time = max6900_rtc_set_time,
aa5bd7e9 DF	209	};
aa5bd7e9 DF	210
6fd5c03f AZ	211	static int
6fd5c03f AZ	212	max6900_probe(struct i2c_client client, const struct i2c_device_id id)
aa5bd7e9	213	{
6fd5c03f	214	struct rtc_device *rtc;
aa5bd7e9	215
6fd5c03f AZ	216	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
6fd5c03f AZ	217	return -ENODEV;
aa5bd7e9	218
feb141d1 JH	219	rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name,
feb141d1 JH	220	&max6900_rtc_ops, THIS_MODULE);
6fd5c03f AZ	221	if (IS_ERR(rtc))
6fd5c03f AZ	222	return PTR_ERR(rtc);
aa5bd7e9 DF	223
	224	i2c_set_clientdata(client, rtc);
	225
	226	return 0;
aa5bd7e9 DF	227	}
aa5bd7e9 DF	228
fe102c71 AZ	229	static struct i2c_device_id max6900_id[] = {
	230	{ "max6900", 0 },
	231	{ }
	232	};
8ad0f5b6	233	MODULE_DEVICE_TABLE(i2c, max6900_id);
fe102c71	234
6fd5c03f AZ	235	static struct i2c_driver max6900_driver = {
	236	.driver = {
	237	.name = "rtc-max6900",
	238	},
	239	.probe = max6900_probe,
fe102c71	240	.id_table = max6900_id,
6fd5c03f AZ	241	};
6fd5c03f AZ	242
0abc9201	243	module_i2c_driver(max6900_driver);
aa5bd7e9 DF	244
aa5bd7e9 DF	245	MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
6fd5c03f	246	MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>");
aa5bd7e9	247	MODULE_LICENSE("GPL");