[linux.git] / drivers / rtc / rtc-mcp795.c

/*
 * SPI Driver for Microchip MCP795 RTC
 *
 * Copyright (C) Josef Gajdusek <[email protected]>
 *
 * based on other Linux RTC drivers
 *
 * Device datasheet:
 * http://ww1.microchip.com/downloads/en/DeviceDoc/22280A.pdf
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/printk.h>
#include <linux/spi/spi.h>
#include <linux/rtc.h>
#include <linux/of.h>
#include <linux/bcd.h>

/* MCP795 Instructions, see datasheet table 3-1 */
#define MCP795_EEREAD	0x03
#define MCP795_EEWRITE	0x02
#define MCP795_EEWRDI	0x04
#define MCP795_EEWREN	0x06
#define MCP795_SRREAD	0x05
#define MCP795_SRWRITE	0x01
#define MCP795_READ		0x13
#define MCP795_WRITE	0x12
#define MCP795_UNLOCK	0x14
#define MCP795_IDWRITE	0x32
#define MCP795_IDREAD	0x33
#define MCP795_CLRWDT	0x44
#define MCP795_CLRRAM	0x54

#define MCP795_ST_BIT	0x80
#define MCP795_24_BIT	0x40

static int mcp795_rtcc_read(struct device *dev, u8 addr, u8 *buf, u8 count)
{
	struct spi_device *spi = to_spi_device(dev);
	int ret;
	u8 tx[2];

	tx[0] = MCP795_READ;
	tx[1] = addr;
	ret = spi_write_then_read(spi, tx, sizeof(tx), buf, count);

	if (ret)
		dev_err(dev, "Failed reading %d bytes from address %x.\n",
					count, addr);

	return ret;
}

static int mcp795_rtcc_write(struct device *dev, u8 addr, u8 *data, u8 count)
{
	struct spi_device *spi = to_spi_device(dev);
	int ret;
	u8 tx[2 + count];

	tx[0] = MCP795_WRITE;
	tx[1] = addr;
	memcpy(&tx[2], data, count);

	ret = spi_write(spi, tx, 2 + count);

	if (ret)
		dev_err(dev, "Failed to write %d bytes to address %x.\n",
					count, addr);

	return ret;
}

static int mcp795_rtcc_set_bits(struct device *dev, u8 addr, u8 mask, u8 state)
{
	int ret;
	u8 tmp;

	ret = mcp795_rtcc_read(dev, addr, &tmp, 1);
	if (ret)
		return ret;

	if ((tmp & mask) != state) {
		tmp = (tmp & ~mask) | state;
		ret = mcp795_rtcc_write(dev, addr, &tmp, 1);
	}

	return ret;
}

static int mcp795_set_time(struct device *dev, struct rtc_time *tim)
{
	int ret;
	u8 data[7];

	/* Read first, so we can leave config bits untouched */
	ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));

	if (ret)
		return ret;

	data[0] = (data[0] & 0x80) | bin2bcd(tim->tm_sec);
	data[1] = (data[1] & 0x80) | bin2bcd(tim->tm_min);
	data[2] = bin2bcd(tim->tm_hour);
	data[4] = bin2bcd(tim->tm_mday);
	data[5] = (data[5] & 0x10) | bin2bcd(tim->tm_mon);

	if (tim->tm_year > 100)
		tim->tm_year -= 100;

	data[6] = bin2bcd(tim->tm_year);

	ret = mcp795_rtcc_write(dev, 0x01, data, sizeof(data));

	if (ret)
		return ret;

	dev_dbg(dev, "Set mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
			tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
			tim->tm_hour, tim->tm_min, tim->tm_sec);

	return 0;
}

static int mcp795_read_time(struct device *dev, struct rtc_time *tim)
{
	int ret;
	u8 data[7];

	ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));

	if (ret)
		return ret;

	tim->tm_sec	= bcd2bin(data[0] & 0x7F);
	tim->tm_min	= bcd2bin(data[1] & 0x7F);
	tim->tm_hour	= bcd2bin(data[2] & 0x3F);
	tim->tm_mday	= bcd2bin(data[4] & 0x3F);
	tim->tm_mon	= bcd2bin(data[5] & 0x1F);
	tim->tm_year	= bcd2bin(data[6]) + 100; /* Assume we are in 20xx */

	dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
				tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
				tim->tm_hour, tim->tm_min, tim->tm_sec);

	return rtc_valid_tm(tim);
}

static const struct rtc_class_ops mcp795_rtc_ops = {
		.read_time = mcp795_read_time,
		.set_time = mcp795_set_time
};

static int mcp795_probe(struct spi_device *spi)
{
	struct rtc_device *rtc;
	int ret;

	spi->mode = SPI_MODE_0;
	spi->bits_per_word = 8;
	ret = spi_setup(spi);
	if (ret) {
		dev_err(&spi->dev, "Unable to setup SPI\n");
		return ret;
	}

	/* Start the oscillator */
	mcp795_rtcc_set_bits(&spi->dev, 0x01, MCP795_ST_BIT, MCP795_ST_BIT);
	/* Clear the 12 hour mode flag*/
	mcp795_rtcc_set_bits(&spi->dev, 0x03, MCP795_24_BIT, 0);

	rtc = devm_rtc_device_register(&spi->dev, "rtc-mcp795",
								&mcp795_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	spi_set_drvdata(spi, rtc);

	return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id mcp795_of_match[] = {
	{ .compatible = "maxim,mcp795" },
	{ }
};
MODULE_DEVICE_TABLE(of, mcp795_of_match);
#endif

static struct spi_driver mcp795_driver = {
		.driver = {
				.name = "rtc-mcp795",
				.of_match_table = of_match_ptr(mcp795_of_match),
		},
		.probe = mcp795_probe,
};

module_spi_driver(mcp795_driver);

MODULE_DESCRIPTION("MCP795 RTC SPI Driver");
MODULE_AUTHOR("Josef Gajdusek <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:mcp795");
Commit	Line	Data
1fcbe42c JG	1	/*
	2	* SPI Driver for Microchip MCP795 RTC
	3	*
	4	* Copyright (C) Josef Gajdusek <[email protected]>
	5	*
	6	* based on other Linux RTC drivers
	7	*
	8	* Device datasheet:
	9	* http://ww1.microchip.com/downloads/en/DeviceDoc/22280A.pdf
	10	*
	11	* This program is free software; you can redistribute it and/or modify
	12	* it under the terms of the GNU General Public License version 2 as
	13	* published by the Free Software Foundation.
	14	*
	15	* */
	16
	17	#include <linux/module.h>
	18	#include <linux/kernel.h>
	19	#include <linux/device.h>
	20	#include <linux/printk.h>
	21	#include <linux/spi/spi.h>
	22	#include <linux/rtc.h>
7f8a5892	23	#include <linux/of.h>
bcf18d88	24	#include <linux/bcd.h>
1fcbe42c JG	25
	26	/* MCP795 Instructions, see datasheet table 3-1 */
	27	#define MCP795_EEREAD 0x03
	28	#define MCP795_EEWRITE 0x02
	29	#define MCP795_EEWRDI 0x04
	30	#define MCP795_EEWREN 0x06
	31	#define MCP795_SRREAD 0x05
	32	#define MCP795_SRWRITE 0x01
	33	#define MCP795_READ 0x13
	34	#define MCP795_WRITE 0x12
	35	#define MCP795_UNLOCK 0x14
	36	#define MCP795_IDWRITE 0x32
	37	#define MCP795_IDREAD 0x33
	38	#define MCP795_CLRWDT 0x44
	39	#define MCP795_CLRRAM 0x54
	40
	41	#define MCP795_ST_BIT 0x80
	42	#define MCP795_24_BIT 0x40
	43
	44	static int mcp795_rtcc_read(struct device dev, u8 addr, u8 buf, u8 count)
	45	{
	46	struct spi_device *spi = to_spi_device(dev);
	47	int ret;
	48	u8 tx[2];
	49
	50	tx[0] = MCP795_READ;
	51	tx[1] = addr;
	52	ret = spi_write_then_read(spi, tx, sizeof(tx), buf, count);
	53
	54	if (ret)
	55	dev_err(dev, "Failed reading %d bytes from address %x.\n",
	56	count, addr);
	57
	58	return ret;
	59	}
	60
	61	static int mcp795_rtcc_write(struct device dev, u8 addr, u8 data, u8 count)
	62	{
	63	struct spi_device *spi = to_spi_device(dev);
	64	int ret;
	65	u8 tx[2 + count];
	66
	67	tx[0] = MCP795_WRITE;
	68	tx[1] = addr;
	69	memcpy(&tx[2], data, count);
	70
	71	ret = spi_write(spi, tx, 2 + count);
	72
	73	if (ret)
	74	dev_err(dev, "Failed to write %d bytes to address %x.\n",
	75	count, addr);
	76
	77	return ret;
	78	}
	79
	80	static int mcp795_rtcc_set_bits(struct device *dev, u8 addr, u8 mask, u8 state)
	81	{
	82	int ret;
	83	u8 tmp;
	84
	85	ret = mcp795_rtcc_read(dev, addr, &tmp, 1);
	86	if (ret)
	87	return ret;
	88
89	if ((tmp & mask) != state) {
90	tmp = (tmp & ~mask) \| state;
91	ret = mcp795_rtcc_write(dev, addr, &tmp, 1);
92	}
93
94	return ret;
95	}
96
97	static int mcp795_set_time(struct device dev, struct rtc_time tim)
98	{
99	int ret;
100	u8 data[7];
101
102	/* Read first, so we can leave config bits untouched */
103	ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
104
105	if (ret)
106	return ret;
107
bcf18d88 EB	108	data[0] = (data[0] & 0x80) \| bin2bcd(tim->tm_sec);
	109	data[1] = (data[1] & 0x80) \| bin2bcd(tim->tm_min);
	110	data[2] = bin2bcd(tim->tm_hour);
	111	data[4] = bin2bcd(tim->tm_mday);
	112	data[5] = (data[5] & 0x10) \| bin2bcd(tim->tm_mon);
1fcbe42c JG	113
	114	if (tim->tm_year > 100)
	115	tim->tm_year -= 100;
	116
bcf18d88	117	data[6] = bin2bcd(tim->tm_year);
1fcbe42c JG	118
	119	ret = mcp795_rtcc_write(dev, 0x01, data, sizeof(data));
	120
	121	if (ret)
	122	return ret;
	123
	124	dev_dbg(dev, "Set mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
	125	tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
	126	tim->tm_hour, tim->tm_min, tim->tm_sec);
	127
	128	return 0;
	129	}
	130
	131	static int mcp795_read_time(struct device dev, struct rtc_time tim)
	132	{
	133	int ret;
	134	u8 data[7];
	135
	136	ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
	137
	138	if (ret)
	139	return ret;
	140
bcf18d88 EB	141	tim->tm_sec = bcd2bin(data[0] & 0x7F);
	142	tim->tm_min = bcd2bin(data[1] & 0x7F);
	143	tim->tm_hour = bcd2bin(data[2] & 0x3F);
	144	tim->tm_mday = bcd2bin(data[4] & 0x3F);
	145	tim->tm_mon = bcd2bin(data[5] & 0x1F);
	146	tim->tm_year = bcd2bin(data[6]) + 100; /* Assume we are in 20xx */
1fcbe42c JG	147
	148	dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
	149	tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
	150	tim->tm_hour, tim->tm_min, tim->tm_sec);
	151
	152	return rtc_valid_tm(tim);
	153	}
	154
34c7b3ac	155	static const struct rtc_class_ops mcp795_rtc_ops = {
1fcbe42c JG	156	.read_time = mcp795_read_time,
	157	.set_time = mcp795_set_time
	158	};
	159
	160	static int mcp795_probe(struct spi_device *spi)
	161	{
	162	struct rtc_device *rtc;
	163	int ret;
	164
	165	spi->mode = SPI_MODE_0;
	166	spi->bits_per_word = 8;
	167	ret = spi_setup(spi);
	168	if (ret) {
	169	dev_err(&spi->dev, "Unable to setup SPI\n");
	170	return ret;
	171	}
	172
	173	/* Start the oscillator */
	174	mcp795_rtcc_set_bits(&spi->dev, 0x01, MCP795_ST_BIT, MCP795_ST_BIT);
	175	/* Clear the 12 hour mode flag*/
	176	mcp795_rtcc_set_bits(&spi->dev, 0x03, MCP795_24_BIT, 0);
	177
	178	rtc = devm_rtc_device_register(&spi->dev, "rtc-mcp795",
	179	&mcp795_rtc_ops, THIS_MODULE);
	180	if (IS_ERR(rtc))
	181	return PTR_ERR(rtc);
	182
	183	spi_set_drvdata(spi, rtc);
	184
	185	return 0;
	186	}
	187
7f8a5892 EB	188	#ifdef CONFIG_OF
	189	static const struct of_device_id mcp795_of_match[] = {
	190	{ .compatible = "maxim,mcp795" },
	191	{ }
	192	};
	193	MODULE_DEVICE_TABLE(of, mcp795_of_match);
	194	#endif
	195
1fcbe42c JG	196	static struct spi_driver mcp795_driver = {
	197	.driver = {
	198	.name = "rtc-mcp795",
7f8a5892	199	.of_match_table = of_match_ptr(mcp795_of_match),
1fcbe42c JG	200	},
	201	.probe = mcp795_probe,
	202	};
	203
	204	module_spi_driver(mcp795_driver);
	205
	206	MODULE_DESCRIPTION("MCP795 RTC SPI Driver");
	207	MODULE_AUTHOR("Josef Gajdusek <[email protected]>");
	208	MODULE_LICENSE("GPL");
	209	MODULE_ALIAS("spi:mcp795");