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

// SPDX-License-Identifier: GPL-2.0-only
/*
 * rtc class driver for the Maxim MAX6900 chip
 *
 * Copyright (c) 2007 MontaVista, Software, Inc.
 *
 * Author: Dale Farnsworth <dale@farnsworth.org>
 *
 * based on previously existing rtc class drivers
 */

#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_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct i2c_client *client = to_i2c_client(dev);
	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 0;
}

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_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct i2c_client *client = to_i2c_client(dev);
	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 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)
{
	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 const 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_new = 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
cd13635e	1	// SPDX-License-Identifier: GPL-2.0-only
aa5bd7e9 DF	2	/*
	3	* rtc class driver for the Maxim MAX6900 chip
	4	*
cd13635e NI	5	* Copyright (c) 2007 MontaVista, Software, Inc.
cd13635e NI	6	*
aa5bd7e9 DF	7	* Author: Dale Farnsworth <dale@farnsworth.org>
	8	*
	9	* based on previously existing rtc class drivers
aa5bd7e9 DF	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/i2c.h>
	14	#include <linux/bcd.h>
	15	#include <linux/rtc.h>
	16	#include <linux/delay.h>
	17
aa5bd7e9 DF	18	/*
	19	* register indices
	20	*/
6fd5c03f AZ	21	#define MAX6900_REG_SC 0 /* seconds 00-59 */
	22	#define MAX6900_REG_MN 1 /* minutes 00-59 */
	23	#define MAX6900_REG_HR 2 /* hours 00-23 */
	24	#define MAX6900_REG_DT 3 /* day of month 00-31 */
	25	#define MAX6900_REG_MO 4 /* month 01-12 */
	26	#define MAX6900_REG_DW 5 /* day of week 1-7 */
	27	#define MAX6900_REG_YR 6 /* year 00-99 */
aa5bd7e9	28	#define MAX6900_REG_CT 7 /* control */
8a2601f6 DF	29	/* register 8 is undocumented */
	30	#define MAX6900_REG_CENTURY 9 /* century */
	31	#define MAX6900_REG_LEN 10
	32
	33	#define MAX6900_BURST_LEN 8 /* can burst r/w first 8 regs */
aa5bd7e9 DF	34
	35	#define MAX6900_REG_CT_WP (1 << 7) /* Write Protect */
	36
	37	/*
	38	* register read/write commands
	39	*/
	40	#define MAX6900_REG_CONTROL_WRITE 0x8e
8a2601f6 DF	41	#define MAX6900_REG_CENTURY_WRITE 0x92
8a2601f6 DF	42	#define MAX6900_REG_CENTURY_READ 0x93
aa5bd7e9	43	#define MAX6900_REG_RESERVED_READ 0x96
8a2601f6 DF	44	#define MAX6900_REG_BURST_WRITE 0xbe
8a2601f6 DF	45	#define MAX6900_REG_BURST_READ 0xbf
aa5bd7e9 DF	46
	47	#define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */
	48
6fd5c03f	49	static struct i2c_driver max6900_driver;
aa5bd7e9 DF	50
	51	static int max6900_i2c_read_regs(struct i2c_client client, u8 buf)
	52	{
8a2601f6 DF	53	u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ };
	54	u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ };
	55	struct i2c_msg msgs[4] = {
aa5bd7e9	56	{
6fd5c03f AZ	57	.addr = client->addr,
	58	.flags = 0, /* write */
	59	.len = sizeof(reg_burst_read),
	60	.buf = reg_burst_read}
	61	,
aa5bd7e9	62	{
6fd5c03f AZ	63	.addr = client->addr,
	64	.flags = I2C_M_RD,
	65	.len = MAX6900_BURST_LEN,
	66	.buf = buf}
	67	,
8a2601f6	68	{
6fd5c03f AZ	69	.addr = client->addr,
	70	.flags = 0, /* write */
	71	.len = sizeof(reg_century_read),
	72	.buf = reg_century_read}
	73	,
8a2601f6	74	{
6fd5c03f AZ	75	.addr = client->addr,
	76	.flags = I2C_M_RD,
	77	.len = sizeof(buf[MAX6900_REG_CENTURY]),
	78	.buf = &buf[MAX6900_REG_CENTURY]
	79	}
aa5bd7e9 DF	80	};
	81	int rc;
	82
	83	rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	84	if (rc != ARRAY_SIZE(msgs)) {
6fd5c03f	85	dev_err(&client->dev, "%s: register read failed\n", __func__);
aa5bd7e9 DF	86	return -EIO;
	87	}
	88	return 0;
	89	}
	90
	91	static int max6900_i2c_write_regs(struct i2c_client client, u8 const buf)
	92	{
8a2601f6 DF	93	u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE };
8a2601f6 DF	94	struct i2c_msg century_msgs[1] = {
aa5bd7e9	95	{
6fd5c03f AZ	96	.addr = client->addr,
	97	.flags = 0, /* write */
	98	.len = sizeof(i2c_century_buf),
	99	.buf = i2c_century_buf}
8a2601f6 DF	100	};
	101	u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE };
	102	struct i2c_msg burst_msgs[1] = {
	103	{
6fd5c03f AZ	104	.addr = client->addr,
	105	.flags = 0, /* write */
	106	.len = sizeof(i2c_burst_buf),
	107	.buf = i2c_burst_buf}
aa5bd7e9 DF	108	};
	109	int rc;
	110
8a2601f6 DF	111	/*
	112	* We have to make separate calls to i2c_transfer because of
	113	* the need to delay after each write to the chip. Also,
	114	* we write the century byte first, since we set the write-protect
	115	* bit as part of the burst write.
	116	*/
	117	i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];
6fd5c03f	118
8a2601f6 DF	119	rc = i2c_transfer(client->adapter, century_msgs,
	120	ARRAY_SIZE(century_msgs));
	121	if (rc != ARRAY_SIZE(century_msgs))
	122	goto write_failed;
6fd5c03f	123
8a2601f6	124	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
aa5bd7e9	125
8a2601f6 DF	126	memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN);
	127
	128	rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs));
	129	if (rc != ARRAY_SIZE(burst_msgs))
	130	goto write_failed;
aa5bd7e9	131	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
8a2601f6	132
aa5bd7e9	133	return 0;
8a2601f6	134
6fd5c03f AZ	135	write_failed:
6fd5c03f AZ	136	dev_err(&client->dev, "%s: register write failed\n", __func__);
8a2601f6	137	return -EIO;
aa5bd7e9 DF	138	}
aa5bd7e9 DF	139
859a6ddb	140	static int max6900_rtc_read_time(struct device dev, struct rtc_time tm)
aa5bd7e9	141	{
859a6ddb	142	struct i2c_client *client = to_i2c_client(dev);
aa5bd7e9 DF	143	int rc;
	144	u8 regs[MAX6900_REG_LEN];
	145
	146	rc = max6900_i2c_read_regs(client, regs);
	147	if (rc < 0)
	148	return rc;
	149
fe20ba70 AB	150	tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]);
	151	tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]);
	152	tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f);
	153	tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]);
	154	tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1;
	155	tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) +
	156	bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
	157	tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]);
aa5bd7e9	158
ceed43f7	159	return 0;
aa5bd7e9 DF	160	}
	161
	162	static int max6900_i2c_clear_write_protect(struct i2c_client *client)
	163	{
f16189ac	164	return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0);
aa5bd7e9 DF	165	}
aa5bd7e9 DF	166
859a6ddb	167	static int max6900_rtc_set_time(struct device dev, struct rtc_time tm)
aa5bd7e9	168	{
859a6ddb	169	struct i2c_client *client = to_i2c_client(dev);
aa5bd7e9 DF	170	u8 regs[MAX6900_REG_LEN];
	171	int rc;
	172
	173	rc = max6900_i2c_clear_write_protect(client);
	174	if (rc < 0)
	175	return rc;
	176
fe20ba70 AB	177	regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec);
	178	regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min);
	179	regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour);
	180	regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday);
	181	regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1);
	182	regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday);
	183	regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100);
	184	regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
8a2601f6 DF	185	/* set write protect */
8a2601f6 DF	186	regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;
aa5bd7e9 DF	187
	188	rc = max6900_i2c_write_regs(client, regs);
	189	if (rc < 0)
	190	return rc;
	191
	192	return 0;
	193	}
	194
aa5bd7e9	195	static const struct rtc_class_ops max6900_rtc_ops = {
6fd5c03f AZ	196	.read_time = max6900_rtc_read_time,
6fd5c03f AZ	197	.set_time = max6900_rtc_set_time,
aa5bd7e9 DF	198	};
aa5bd7e9 DF	199
3f4a3322	200	static int max6900_probe(struct i2c_client *client)
aa5bd7e9	201	{
6fd5c03f	202	struct rtc_device *rtc;
aa5bd7e9	203
6fd5c03f AZ	204	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
6fd5c03f AZ	205	return -ENODEV;
aa5bd7e9	206
feb141d1 JH	207	rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name,
feb141d1 JH	208	&max6900_rtc_ops, THIS_MODULE);
6fd5c03f AZ	209	if (IS_ERR(rtc))
6fd5c03f AZ	210	return PTR_ERR(rtc);
aa5bd7e9 DF	211
	212	i2c_set_clientdata(client, rtc);
	213
	214	return 0;
aa5bd7e9 DF	215	}
aa5bd7e9 DF	216
45a63518	217	static const struct i2c_device_id max6900_id[] = {
fe102c71 AZ	218	{ "max6900", 0 },
	219	{ }
	220	};
8ad0f5b6	221	MODULE_DEVICE_TABLE(i2c, max6900_id);
fe102c71	222
6fd5c03f AZ	223	static struct i2c_driver max6900_driver = {
	224	.driver = {
	225	.name = "rtc-max6900",
	226	},
3f4a3322	227	.probe_new = max6900_probe,
fe102c71	228	.id_table = max6900_id,
6fd5c03f AZ	229	};
6fd5c03f AZ	230
0abc9201	231	module_i2c_driver(max6900_driver);
aa5bd7e9 DF	232
aa5bd7e9 DF	233	MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
6fd5c03f	234	MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>");
aa5bd7e9	235	MODULE_LICENSE("GPL");