[mirror_ubuntu-jammy-kernel.git] / drivers / rtc / rtc-max6902.c

// SPDX-License-Identifier: GPL-2.0-only
/* drivers/rtc/rtc-max6902.c
 *
 * Copyright (C) 2006 8D Technologies inc.
 * Copyright (C) 2004 Compulab Ltd.
 *
 * Driver for MAX6902 spi RTC
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>

#define MAX6902_REG_SECONDS		0x01
#define MAX6902_REG_MINUTES		0x03
#define MAX6902_REG_HOURS		0x05
#define MAX6902_REG_DATE		0x07
#define MAX6902_REG_MONTH		0x09
#define MAX6902_REG_DAY			0x0B
#define MAX6902_REG_YEAR		0x0D
#define MAX6902_REG_CONTROL		0x0F
#define MAX6902_REG_CENTURY		0x13

static int max6902_set_reg(struct device *dev, unsigned char address,
				unsigned char data)
{
	struct spi_device *spi = to_spi_device(dev);
	unsigned char buf[2];

	/* MSB must be '0' to write */
	buf[0] = address & 0x7f;
	buf[1] = data;

	return spi_write_then_read(spi, buf, 2, NULL, 0);
}

static int max6902_get_reg(struct device *dev, unsigned char address,
				unsigned char *data)
{
	struct spi_device *spi = to_spi_device(dev);

	/* Set MSB to indicate read */
	*data = address | 0x80;

	return spi_write_then_read(spi, data, 1, data, 1);
}

static int max6902_read_time(struct device *dev, struct rtc_time *dt)
{
	int err, century;
	struct spi_device *spi = to_spi_device(dev);
	unsigned char buf[8];

	buf[0] = 0xbf;	/* Burst read */

	err = spi_write_then_read(spi, buf, 1, buf, 8);
	if (err != 0)
		return err;

	/* The chip sends data in this order:
	 * Seconds, Minutes, Hours, Date, Month, Day, Year */
	dt->tm_sec	= bcd2bin(buf[0]);
	dt->tm_min	= bcd2bin(buf[1]);
	dt->tm_hour	= bcd2bin(buf[2]);
	dt->tm_mday	= bcd2bin(buf[3]);
	dt->tm_mon	= bcd2bin(buf[4]) - 1;
	dt->tm_wday	= bcd2bin(buf[5]);
	dt->tm_year	= bcd2bin(buf[6]);

	/* Read century */
	err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]);
	if (err != 0)
		return err;

	century = bcd2bin(buf[0]) * 100;

	dt->tm_year += century;
	dt->tm_year -= 1900;

	return 0;
}

static int max6902_set_time(struct device *dev, struct rtc_time *dt)
{
	dt->tm_year = dt->tm_year + 1900;

	/* Remove write protection */
	max6902_set_reg(dev, MAX6902_REG_CONTROL, 0);

	max6902_set_reg(dev, MAX6902_REG_SECONDS, bin2bcd(dt->tm_sec));
	max6902_set_reg(dev, MAX6902_REG_MINUTES, bin2bcd(dt->tm_min));
	max6902_set_reg(dev, MAX6902_REG_HOURS, bin2bcd(dt->tm_hour));

	max6902_set_reg(dev, MAX6902_REG_DATE, bin2bcd(dt->tm_mday));
	max6902_set_reg(dev, MAX6902_REG_MONTH, bin2bcd(dt->tm_mon + 1));
	max6902_set_reg(dev, MAX6902_REG_DAY, bin2bcd(dt->tm_wday));
	max6902_set_reg(dev, MAX6902_REG_YEAR, bin2bcd(dt->tm_year % 100));
	max6902_set_reg(dev, MAX6902_REG_CENTURY, bin2bcd(dt->tm_year / 100));

	/* Compulab used a delay here. However, the datasheet
	 * does not mention a delay being required anywhere... */
	/* delay(2000); */

	/* Write protect */
	max6902_set_reg(dev, MAX6902_REG_CONTROL, 0x80);

	return 0;
}

static const struct rtc_class_ops max6902_rtc_ops = {
	.read_time	= max6902_read_time,
	.set_time	= max6902_set_time,
};

static int max6902_probe(struct spi_device *spi)
{
	struct rtc_device *rtc;
	unsigned char tmp;
	int res;

	spi->mode = SPI_MODE_3;
	spi->bits_per_word = 8;
	spi_setup(spi);

	res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
	if (res != 0)
		return res;

	rtc = devm_rtc_device_register(&spi->dev, "max6902",
				&max6902_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	spi_set_drvdata(spi, rtc);
	return 0;
}

static struct spi_driver max6902_driver = {
	.driver = {
		.name	= "rtc-max6902",
	},
	.probe	= max6902_probe,
};

module_spi_driver(max6902_driver);

MODULE_DESCRIPTION("max6902 spi RTC driver");
MODULE_AUTHOR("Raphael Assenat");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-max6902");
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
f30c2269	2	/* drivers/rtc/rtc-max6902.c
8e12ecc2 RA	3	*
	4	* Copyright (C) 2006 8D Technologies inc.
	5	* Copyright (C) 2004 Compulab Ltd.
	6	*
8e12ecc2	7	* Driver for MAX6902 spi RTC
8e12ecc2 RA	8	*/
8e12ecc2 RA	9
8e12ecc2	10	#include <linux/module.h>
8e12ecc2 RA	11	#include <linux/kernel.h>
	12	#include <linux/platform_device.h>
	13	#include <linux/init.h>
	14	#include <linux/rtc.h>
	15	#include <linux/spi/spi.h>
	16	#include <linux/bcd.h>
8e12ecc2 RA	17
	18	#define MAX6902_REG_SECONDS 0x01
	19	#define MAX6902_REG_MINUTES 0x03
	20	#define MAX6902_REG_HOURS 0x05
	21	#define MAX6902_REG_DATE 0x07
	22	#define MAX6902_REG_MONTH 0x09
	23	#define MAX6902_REG_DAY 0x0B
	24	#define MAX6902_REG_YEAR 0x0D
	25	#define MAX6902_REG_CONTROL 0x0F
	26	#define MAX6902_REG_CENTURY 0x13
	27
a5771c6c	28	static int max6902_set_reg(struct device *dev, unsigned char address,
8e12ecc2 RA	29	unsigned char data)
	30	{
	31	struct spi_device *spi = to_spi_device(dev);
	32	unsigned char buf[2];
	33
	34	/* MSB must be '0' to write */
	35	buf[0] = address & 0x7f;
	36	buf[1] = data;
	37
a5771c6c	38	return spi_write_then_read(spi, buf, 2, NULL, 0);
8e12ecc2 RA	39	}
	40
	41	static int max6902_get_reg(struct device *dev, unsigned char address,
	42	unsigned char *data)
	43	{
	44	struct spi_device *spi = to_spi_device(dev);
8e12ecc2 RA	45
8e12ecc2 RA	46	/* Set MSB to indicate read */
a5771c6c	47	*data = address \| 0x80;
8e12ecc2	48
a5771c6c	49	return spi_write_then_read(spi, data, 1, data, 1);
8e12ecc2 RA	50	}
8e12ecc2 RA	51
a5771c6c	52	static int max6902_read_time(struct device dev, struct rtc_time dt)
8e12ecc2	53	{
a5771c6c	54	int err, century;
8e12ecc2	55	struct spi_device *spi = to_spi_device(dev);
a5771c6c	56	unsigned char buf[8];
8e12ecc2	57
a5771c6c	58	buf[0] = 0xbf; /* Burst read */
8e12ecc2	59
a5771c6c AZ	60	err = spi_write_then_read(spi, buf, 1, buf, 8);
	61	if (err != 0)
	62	return err;
8e12ecc2 RA	63
	64	/* The chip sends data in this order:
	65	* Seconds, Minutes, Hours, Date, Month, Day, Year */
a5771c6c AZ	66	dt->tm_sec = bcd2bin(buf[0]);
	67	dt->tm_min = bcd2bin(buf[1]);
	68	dt->tm_hour = bcd2bin(buf[2]);
	69	dt->tm_mday = bcd2bin(buf[3]);
	70	dt->tm_mon = bcd2bin(buf[4]) - 1;
	71	dt->tm_wday = bcd2bin(buf[5]);
	72	dt->tm_year = bcd2bin(buf[6]);
	73
	74	/* Read century */
	75	err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]);
	76	if (err != 0)
	77	return err;
8e12ecc2	78
a5771c6c	79	century = bcd2bin(buf[0]) * 100;
8e12ecc2 RA	80
	81	dt->tm_year += century;
	82	dt->tm_year -= 1900;
	83
22652ba7	84	return 0;
8e12ecc2 RA	85	}
8e12ecc2 RA	86
a5771c6c	87	static int max6902_set_time(struct device dev, struct rtc_time dt)
8e12ecc2	88	{
a5771c6c	89	dt->tm_year = dt->tm_year + 1900;
8e12ecc2 RA	90
8e12ecc2 RA	91	/* Remove write protection */
08348d2f	92	max6902_set_reg(dev, MAX6902_REG_CONTROL, 0);
8e12ecc2	93
08348d2f AL	94	max6902_set_reg(dev, MAX6902_REG_SECONDS, bin2bcd(dt->tm_sec));
	95	max6902_set_reg(dev, MAX6902_REG_MINUTES, bin2bcd(dt->tm_min));
	96	max6902_set_reg(dev, MAX6902_REG_HOURS, bin2bcd(dt->tm_hour));
8e12ecc2	97
08348d2f AL	98	max6902_set_reg(dev, MAX6902_REG_DATE, bin2bcd(dt->tm_mday));
	99	max6902_set_reg(dev, MAX6902_REG_MONTH, bin2bcd(dt->tm_mon + 1));
	100	max6902_set_reg(dev, MAX6902_REG_DAY, bin2bcd(dt->tm_wday));
	101	max6902_set_reg(dev, MAX6902_REG_YEAR, bin2bcd(dt->tm_year % 100));
	102	max6902_set_reg(dev, MAX6902_REG_CENTURY, bin2bcd(dt->tm_year / 100));
8e12ecc2 RA	103
	104	/* Compulab used a delay here. However, the datasheet
	105	* does not mention a delay being required anywhere... */
	106	/* delay(2000); */
	107
	108	/* Write protect */
08348d2f	109	max6902_set_reg(dev, MAX6902_REG_CONTROL, 0x80);
8e12ecc2 RA	110
	111	return 0;
	112	}
	113
ff8371ac	114	static const struct rtc_class_ops max6902_rtc_ops = {
8e12ecc2 RA	115	.read_time = max6902_read_time,
	116	.set_time = max6902_set_time,
	117	};
	118
5a167f45	119	static int max6902_probe(struct spi_device *spi)
8e12ecc2 RA	120	{
	121	struct rtc_device *rtc;
	122	unsigned char tmp;
8e12ecc2 RA	123	int res;
8e12ecc2 RA	124
8e12ecc2 RA	125	spi->mode = SPI_MODE_3;
	126	spi->bits_per_word = 8;
	127	spi_setup(spi);
	128
8e12ecc2	129	res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
a5771c6c	130	if (res != 0)
8e12ecc2	131	return res;
a5771c6c	132
04353a73 JH	133	rtc = devm_rtc_device_register(&spi->dev, "max6902",
04353a73 JH	134	&max6902_rtc_ops, THIS_MODULE);
a5771c6c AZ	135	if (IS_ERR(rtc))
a5771c6c AZ	136	return PTR_ERR(rtc);
8e12ecc2	137
a5ef73f0	138	spi_set_drvdata(spi, rtc);
8e12ecc2 RA	139	return 0;
	140	}
	141
8e12ecc2 RA	142	static struct spi_driver max6902_driver = {
8e12ecc2 RA	143	.driver = {
5c076fce	144	.name = "rtc-max6902",
8e12ecc2	145	},
5c076fce	146	.probe = max6902_probe,
8e12ecc2 RA	147	};
8e12ecc2 RA	148
109e9418	149	module_spi_driver(max6902_driver);
8e12ecc2	150
83246a16 SK	151	MODULE_DESCRIPTION("max6902 spi RTC driver");
	152	MODULE_AUTHOR("Raphael Assenat");
	153	MODULE_LICENSE("GPL");
e0626e38	154	MODULE_ALIAS("spi:rtc-max6902");