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

/*
 * rtc class driver for the Maxim MAX6900 chip
 *
 * Author: Dale Farnsworth <[email protected]>
 *
 * 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 <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
Commit	Line	Data
aa5bd7e9 DF	1	/*
	2	* rtc class driver for the Maxim MAX6900 chip
	3	*
	4	* Author: Dale Farnsworth <[email protected]>
	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
6fd5c03f	20	#define DRV_VERSION "0.2"
aa5bd7e9 DF	21
	22	/*
	23	* register indices
	24	*/
6fd5c03f AZ	25	#define MAX6900_REG_SC 0 /* seconds 00-59 */
	26	#define MAX6900_REG_MN 1 /* minutes 00-59 */
	27	#define MAX6900_REG_HR 2 /* hours 00-23 */
	28	#define MAX6900_REG_DT 3 /* day of month 00-31 */
	29	#define MAX6900_REG_MO 4 /* month 01-12 */
	30	#define MAX6900_REG_DW 5 /* day of week 1-7 */
	31	#define MAX6900_REG_YR 6 /* year 00-99 */
aa5bd7e9	32	#define MAX6900_REG_CT 7 /* control */
8a2601f6 DF	33	/* register 8 is undocumented */
	34	#define MAX6900_REG_CENTURY 9 /* century */
	35	#define MAX6900_REG_LEN 10
	36
	37	#define MAX6900_BURST_LEN 8 /* can burst r/w first 8 regs */
aa5bd7e9 DF	38
	39	#define MAX6900_REG_CT_WP (1 << 7) /* Write Protect */
	40
	41	/*
	42	* register read/write commands
	43	*/
	44	#define MAX6900_REG_CONTROL_WRITE 0x8e
8a2601f6 DF	45	#define MAX6900_REG_CENTURY_WRITE 0x92
8a2601f6 DF	46	#define MAX6900_REG_CENTURY_READ 0x93
aa5bd7e9	47	#define MAX6900_REG_RESERVED_READ 0x96
8a2601f6 DF	48	#define MAX6900_REG_BURST_WRITE 0xbe
8a2601f6 DF	49	#define MAX6900_REG_BURST_READ 0xbf
aa5bd7e9 DF	50
	51	#define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */
	52
6fd5c03f	53	static struct i2c_driver max6900_driver;
aa5bd7e9 DF	54
	55	static int max6900_i2c_read_regs(struct i2c_client client, u8 buf)
	56	{
8a2601f6 DF	57	u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ };
	58	u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ };
	59	struct i2c_msg msgs[4] = {
aa5bd7e9	60	{
6fd5c03f AZ	61	.addr = client->addr,
	62	.flags = 0, /* write */
	63	.len = sizeof(reg_burst_read),
	64	.buf = reg_burst_read}
	65	,
aa5bd7e9	66	{
6fd5c03f AZ	67	.addr = client->addr,
	68	.flags = I2C_M_RD,
	69	.len = MAX6900_BURST_LEN,
	70	.buf = buf}
	71	,
8a2601f6	72	{
6fd5c03f AZ	73	.addr = client->addr,
	74	.flags = 0, /* write */
	75	.len = sizeof(reg_century_read),
	76	.buf = reg_century_read}
	77	,
8a2601f6	78	{
6fd5c03f AZ	79	.addr = client->addr,
	80	.flags = I2C_M_RD,
	81	.len = sizeof(buf[MAX6900_REG_CENTURY]),
	82	.buf = &buf[MAX6900_REG_CENTURY]
	83	}
aa5bd7e9 DF	84	};
	85	int rc;
	86
	87	rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	88	if (rc != ARRAY_SIZE(msgs)) {
6fd5c03f	89	dev_err(&client->dev, "%s: register read failed\n", __func__);
aa5bd7e9 DF	90	return -EIO;
	91	}
	92	return 0;
	93	}
	94
	95	static int max6900_i2c_write_regs(struct i2c_client client, u8 const buf)
	96	{
8a2601f6 DF	97	u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE };
8a2601f6 DF	98	struct i2c_msg century_msgs[1] = {
aa5bd7e9	99	{
6fd5c03f AZ	100	.addr = client->addr,
	101	.flags = 0, /* write */
	102	.len = sizeof(i2c_century_buf),
	103	.buf = i2c_century_buf}
8a2601f6 DF	104	};
	105	u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE };
	106	struct i2c_msg burst_msgs[1] = {
	107	{
6fd5c03f AZ	108	.addr = client->addr,
	109	.flags = 0, /* write */
	110	.len = sizeof(i2c_burst_buf),
	111	.buf = i2c_burst_buf}
aa5bd7e9 DF	112	};
	113	int rc;
	114
8a2601f6 DF	115	/*
	116	* We have to make separate calls to i2c_transfer because of
	117	* the need to delay after each write to the chip. Also,
	118	* we write the century byte first, since we set the write-protect
	119	* bit as part of the burst write.
	120	*/
	121	i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];
6fd5c03f	122
8a2601f6 DF	123	rc = i2c_transfer(client->adapter, century_msgs,
	124	ARRAY_SIZE(century_msgs));
	125	if (rc != ARRAY_SIZE(century_msgs))
	126	goto write_failed;
6fd5c03f	127
8a2601f6	128	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
aa5bd7e9	129
8a2601f6 DF	130	memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN);
	131
	132	rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs));
	133	if (rc != ARRAY_SIZE(burst_msgs))
	134	goto write_failed;
aa5bd7e9	135	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
8a2601f6	136
aa5bd7e9	137	return 0;
8a2601f6	138
6fd5c03f AZ	139	write_failed:
6fd5c03f AZ	140	dev_err(&client->dev, "%s: register write failed\n", __func__);
8a2601f6	141	return -EIO;
aa5bd7e9 DF	142	}
aa5bd7e9 DF	143
aa5bd7e9 DF	144	static int max6900_i2c_read_time(struct i2c_client client, struct rtc_time tm)
	145	{
	146	int rc;
	147	u8 regs[MAX6900_REG_LEN];
	148
	149	rc = max6900_i2c_read_regs(client, regs);
	150	if (rc < 0)
	151	return rc;
	152
fe20ba70 AB	153	tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]);
	154	tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]);
	155	tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f);
	156	tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]);
	157	tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1;
	158	tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) +
	159	bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
	160	tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]);
aa5bd7e9	161
c814dc13	162	return rtc_valid_tm(tm);
aa5bd7e9 DF	163	}
	164
	165	static int max6900_i2c_clear_write_protect(struct i2c_client *client)
	166	{
f16189ac	167	return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0);
aa5bd7e9 DF	168	}
aa5bd7e9 DF	169
6fd5c03f AZ	170	static int
6fd5c03f AZ	171	max6900_i2c_set_time(struct i2c_client client, struct rtc_time const tm)
aa5bd7e9 DF	172	{
	173	u8 regs[MAX6900_REG_LEN];
	174	int rc;
	175
	176	rc = max6900_i2c_clear_write_protect(client);
	177	if (rc < 0)
	178	return rc;
	179
fe20ba70 AB	180	regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec);
	181	regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min);
	182	regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour);
	183	regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday);
	184	regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1);
	185	regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday);
	186	regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100);
	187	regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
8a2601f6 DF	188	/* set write protect */
8a2601f6 DF	189	regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;
aa5bd7e9 DF	190
	191	rc = max6900_i2c_write_regs(client, regs);
	192	if (rc < 0)
	193	return rc;
	194
	195	return 0;
	196	}
	197
	198	static int max6900_rtc_read_time(struct device dev, struct rtc_time tm)
	199	{
	200	return max6900_i2c_read_time(to_i2c_client(dev), tm);
	201	}
	202
	203	static int max6900_rtc_set_time(struct device dev, struct rtc_time tm)
	204	{
	205	return max6900_i2c_set_time(to_i2c_client(dev), tm);
	206	}
	207
aa5bd7e9	208	static const struct rtc_class_ops max6900_rtc_ops = {
6fd5c03f AZ	209	.read_time = max6900_rtc_read_time,
6fd5c03f AZ	210	.set_time = max6900_rtc_set_time,
aa5bd7e9 DF	211	};
aa5bd7e9 DF	212
6fd5c03f AZ	213	static int
6fd5c03f AZ	214	max6900_probe(struct i2c_client client, const struct i2c_device_id id)
aa5bd7e9	215	{
6fd5c03f	216	struct rtc_device *rtc;
aa5bd7e9	217
6fd5c03f AZ	218	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
6fd5c03f AZ	219	return -ENODEV;
aa5bd7e9	220
6fd5c03f	221	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
aa5bd7e9	222
feb141d1 JH	223	rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name,
feb141d1 JH	224	&max6900_rtc_ops, THIS_MODULE);
6fd5c03f AZ	225	if (IS_ERR(rtc))
6fd5c03f AZ	226	return PTR_ERR(rtc);
aa5bd7e9 DF	227
	228	i2c_set_clientdata(client, rtc);
	229
	230	return 0;
aa5bd7e9 DF	231	}
aa5bd7e9 DF	232
fe102c71 AZ	233	static struct i2c_device_id max6900_id[] = {
	234	{ "max6900", 0 },
	235	{ }
	236	};
8ad0f5b6	237	MODULE_DEVICE_TABLE(i2c, max6900_id);
fe102c71	238
6fd5c03f AZ	239	static struct i2c_driver max6900_driver = {
	240	.driver = {
	241	.name = "rtc-max6900",
	242	},
	243	.probe = max6900_probe,
fe102c71	244	.id_table = max6900_id,
6fd5c03f AZ	245	};
6fd5c03f AZ	246
0abc9201	247	module_i2c_driver(max6900_driver);
aa5bd7e9 DF	248
aa5bd7e9 DF	249	MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
6fd5c03f	250	MODULE_AUTHOR("Dale Farnsworth <[email protected]>");
aa5bd7e9 DF	251	MODULE_LICENSE("GPL");
aa5bd7e9 DF	252	MODULE_VERSION(DRV_VERSION);