[linux-2.6-block.git] / drivers / rtc / rtc-mcp795.c

/*
 * SPI Driver for Microchip MCP795 RTC
 *
 * Copyright (C) Josef Gajdusek <atx@atx.name>
 *
 * 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>

/* 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) | ((tim->tm_sec / 10) << 4) | (tim->tm_sec % 10);
	data[1] = (data[1] & 0x80) | ((tim->tm_min / 10) << 4) | (tim->tm_min % 10);
	data[2] = ((tim->tm_hour / 10) << 4) | (tim->tm_hour % 10);
	data[4] = ((tim->tm_mday / 10) << 4) | ((tim->tm_mday) % 10);
	data[5] = (data[5] & 0x10) | (tim->tm_mon / 10) | (tim->tm_mon % 10);

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

	data[6] = ((tim->tm_year / 10) << 4) | (tim->tm_year % 10);

	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		= ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
	tim->tm_min		= ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
	tim->tm_hour	= ((data[2] & 0x30) >> 4) * 10 + (data[2] & 0x0f);
	tim->tm_mday	= ((data[4] & 0x30) >> 4) * 10 + (data[4] & 0x0f);
	tim->tm_mon		= ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
	tim->tm_year	= ((data[6] & 0xf0) >> 4) * 10 + (data[6] & 0x0f) + 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 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 <atx@atx.name>");
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 <atx@atx.name>
	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>
1fcbe42c JG	24
	25	/* MCP795 Instructions, see datasheet table 3-1 */
	26	#define MCP795_EEREAD 0x03
	27	#define MCP795_EEWRITE 0x02
	28	#define MCP795_EEWRDI 0x04
	29	#define MCP795_EEWREN 0x06
	30	#define MCP795_SRREAD 0x05
	31	#define MCP795_SRWRITE 0x01
	32	#define MCP795_READ 0x13
	33	#define MCP795_WRITE 0x12
	34	#define MCP795_UNLOCK 0x14
	35	#define MCP795_IDWRITE 0x32
	36	#define MCP795_IDREAD 0x33
	37	#define MCP795_CLRWDT 0x44
	38	#define MCP795_CLRRAM 0x54
	39
	40	#define MCP795_ST_BIT 0x80
	41	#define MCP795_24_BIT 0x40
	42
	43	static int mcp795_rtcc_read(struct device dev, u8 addr, u8 buf, u8 count)
	44	{
	45	struct spi_device *spi = to_spi_device(dev);
	46	int ret;
	47	u8 tx[2];
	48
	49	tx[0] = MCP795_READ;
	50	tx[1] = addr;
	51	ret = spi_write_then_read(spi, tx, sizeof(tx), buf, count);
	52
	53	if (ret)
	54	dev_err(dev, "Failed reading %d bytes from address %x.\n",
	55	count, addr);
	56
	57	return ret;
	58	}
	59
	60	static int mcp795_rtcc_write(struct device dev, u8 addr, u8 data, u8 count)
	61	{
	62	struct spi_device *spi = to_spi_device(dev);
	63	int ret;
	64	u8 tx[2 + count];
	65
	66	tx[0] = MCP795_WRITE;
	67	tx[1] = addr;
	68	memcpy(&tx[2], data, count);
	69
	70	ret = spi_write(spi, tx, 2 + count);
	71
	72	if (ret)
	73	dev_err(dev, "Failed to write %d bytes to address %x.\n",
	74	count, addr);
	75
	76	return ret;
	77	}
	78
	79	static int mcp795_rtcc_set_bits(struct device *dev, u8 addr, u8 mask, u8 state)
	80	{
	81	int ret;
	82	u8 tmp;
	83
	84	ret = mcp795_rtcc_read(dev, addr, &tmp, 1);
	85	if (ret)
	86	return ret;
	87
88	if ((tmp & mask) != state) {
89	tmp = (tmp & ~mask) \| state;
90	ret = mcp795_rtcc_write(dev, addr, &tmp, 1);
91	}
92
93	return ret;
94	}
95
96	static int mcp795_set_time(struct device dev, struct rtc_time tim)
97	{
98	int ret;
99	u8 data[7];
100
101	/* Read first, so we can leave config bits untouched */
102	ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
103
104	if (ret)
105	return ret;
106
107	data[0] = (data[0] & 0x80) \| ((tim->tm_sec / 10) << 4) \| (tim->tm_sec % 10);
108	data[1] = (data[1] & 0x80) \| ((tim->tm_min / 10) << 4) \| (tim->tm_min % 10);
109	data[2] = ((tim->tm_hour / 10) << 4) \| (tim->tm_hour % 10);
110	data[4] = ((tim->tm_mday / 10) << 4) \| ((tim->tm_mday) % 10);
111	data[5] = (data[5] & 0x10) \| (tim->tm_mon / 10) \| (tim->tm_mon % 10);
112
113	if (tim->tm_year > 100)
114	tim->tm_year -= 100;
115
116	data[6] = ((tim->tm_year / 10) << 4) \| (tim->tm_year % 10);
117
118	ret = mcp795_rtcc_write(dev, 0x01, data, sizeof(data));
119
120	if (ret)
121	return ret;
122
123	dev_dbg(dev, "Set mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
124	tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
125	tim->tm_hour, tim->tm_min, tim->tm_sec);
126
127	return 0;
128	}
129
130	static int mcp795_read_time(struct device dev, struct rtc_time tim)
131	{
132	int ret;
133	u8 data[7];
134
135	ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
136
137	if (ret)
138	return ret;
139
140	tim->tm_sec = ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
141	tim->tm_min = ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
142	tim->tm_hour = ((data[2] & 0x30) >> 4) * 10 + (data[2] & 0x0f);
143	tim->tm_mday = ((data[4] & 0x30) >> 4) * 10 + (data[4] & 0x0f);
144	tim->tm_mon = ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
145	tim->tm_year = ((data[6] & 0xf0) >> 4) * 10 + (data[6] & 0x0f) + 100; /* Assume we are in 20xx */
146
147	dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
148	tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
149	tim->tm_hour, tim->tm_min, tim->tm_sec);
150
151	return rtc_valid_tm(tim);
152	}
153
154	static struct rtc_class_ops mcp795_rtc_ops = {
155	.read_time = mcp795_read_time,
156	.set_time = mcp795_set_time
157	};
158
159	static int mcp795_probe(struct spi_device *spi)
160	{
161	struct rtc_device *rtc;
162	int ret;
163
164	spi->mode = SPI_MODE_0;
165	spi->bits_per_word = 8;
166	ret = spi_setup(spi);
167	if (ret) {
168	dev_err(&spi->dev, "Unable to setup SPI\n");
169	return ret;
170	}
171
172	/* Start the oscillator */
173	mcp795_rtcc_set_bits(&spi->dev, 0x01, MCP795_ST_BIT, MCP795_ST_BIT);
174	/* Clear the 12 hour mode flag*/
175	mcp795_rtcc_set_bits(&spi->dev, 0x03, MCP795_24_BIT, 0);
176
177	rtc = devm_rtc_device_register(&spi->dev, "rtc-mcp795",
178	&mcp795_rtc_ops, THIS_MODULE);
179	if (IS_ERR(rtc))
180	return PTR_ERR(rtc);
181
182	spi_set_drvdata(spi, rtc);
183
184	return 0;
185	}
186
7f8a5892 EB	187	#ifdef CONFIG_OF
	188	static const struct of_device_id mcp795_of_match[] = {
	189	{ .compatible = "maxim,mcp795" },
	190	{ }
	191	};
	192	MODULE_DEVICE_TABLE(of, mcp795_of_match);
	193	#endif
	194
1fcbe42c JG	195	static struct spi_driver mcp795_driver = {
	196	.driver = {
	197	.name = "rtc-mcp795",
7f8a5892	198	.of_match_table = of_match_ptr(mcp795_of_match),
1fcbe42c JG	199	},
	200	.probe = mcp795_probe,
	201	};
	202
	203	module_spi_driver(mcp795_driver);
	204
	205	MODULE_DESCRIPTION("MCP795 RTC SPI Driver");
	206	MODULE_AUTHOR("Josef Gajdusek <atx@atx.name>");
	207	MODULE_LICENSE("GPL");
	208	MODULE_ALIAS("spi:mcp795");