aboutsummaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-max6902.c
blob: 0b20dfacbf595c6fcc1c00855771688582f3780c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
/* drivers/rtc/rtc-max6902.c
 *
 * Copyright (C) 2006 8D Technologies inc.
 * Copyright (C) 2004 Compulab Ltd.
 *
 * 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.
 *
 * Driver for MAX6902 spi RTC
 *
 * Changelog:
 *
 * 24-May-2006: Raphael Assenat <raph@8d.com>
 *                - Major rework
 *   				Converted to rtc_device and uses the SPI layer.
 *
 * ??-???-2005: Someone at Compulab
 *                - Initial driver creation.
 */

#include <linux/module.h>
#include <linux/version.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>
#include <linux/delay.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

#undef MAX6902_DEBUG

struct max6902 {
	struct rtc_device *rtc;
	u8 buf[9]; /* Burst read cmd + 8 registers */
	u8 tx_buf[2];
	u8 rx_buf[2];
};

static void 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;

	spi_write(spi, buf, 2);
}

static int max6902_get_reg(struct device *dev, unsigned char address,
				unsigned char *data)
{
	struct spi_device *spi = to_spi_device(dev);
	struct max6902 *chip = dev_get_drvdata(dev);
	struct spi_message message;
	struct spi_transfer xfer;
	int status;

	if (!data)
		return -EINVAL;

	/* Build our spi message */
	spi_message_init(&message);
	memset(&xfer, 0, sizeof(xfer));
	xfer.len = 2;
	/* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */
	xfer.tx_buf = chip->tx_buf;
	xfer.rx_buf = chip->rx_buf;

	/* Set MSB to indicate read */
	chip->tx_buf[0] = address | 0x80;

	spi_message_add_tail(&xfer, &message);

	/* do the i/o */
	status = spi_sync(spi, &message);
	if (status == 0)
		status = message.status;
	else
		return status;

	*data = chip->rx_buf[1];

	return status;
}

static int max6902_get_datetime(struct device *dev, struct rtc_time *dt)
{
	unsigned char tmp;
	int century;
	int err;
	struct spi_device *spi = to_spi_device(dev);
	struct max6902 *chip = dev_get_drvdata(dev);
	struct spi_message message;
	struct spi_transfer xfer;
	int status;

	err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp);
	if (err)
		return err;

	/* build the message */
	spi_message_init(&message);
	memset(&xfer, 0, sizeof(xfer));
	xfer.len = 1 + 7;	/* Burst read command + 7 registers */
	xfer.tx_buf = chip->buf;
	xfer.rx_buf = chip->buf;
	chip->buf[0] = 0xbf;	/* Burst read */
	spi_message_add_tail(&xfer, &message);

	/* do the i/o */
	status = spi_sync(spi, &message);
	if (status == 0)
		status = message.status;
	else
		return status;

	/* The chip sends data in this order:
	 * Seconds, Minutes, Hours, Date, Month, Day, Year */
	dt->tm_sec	= BCD2BIN(chip->buf[1]);
	dt->tm_min	= BCD2BIN(chip->buf[2]);
	dt->tm_hour	= BCD2BIN(chip->buf[3]);
	dt->tm_mday	= BCD2BIN(chip->buf[4]);
	dt->tm_mon	= BCD2BIN(chip->buf[5] - 1);
	dt->tm_wday	= BCD2BIN(chip->buf[6]);
	dt->tm_year = BCD2BIN(chip->buf[7]);

	century = BCD2BIN(tmp) * 100;

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

#ifdef MAX6902_DEBUG
	printk("\n%s : Read RTC values\n",__FUNCTION__);
	printk("tm_hour: %i\n",dt->tm_hour);
	printk("tm_min : %i\n",dt->tm_min);
	printk("tm_sec : %i\n",dt->tm_sec);
	printk("tm_year: %i\n",dt->tm_year);
	printk("tm_mon : %i\n",dt->tm_mon);
	printk("tm_mday: %i\n",dt->tm_mday);
	printk("tm_wday: %i\n",dt->tm_wday);
#endif

	return 0;
}

static int max6902_set_datetime(struct device *dev, struct rtc_time *dt)
{
	dt->tm_year = dt->tm_year+1900;

#ifdef MAX6902_DEBUG
	printk("\n%s : Setting RTC values\n",__FUNCTION__);
	printk("tm_sec : %i\n",dt->tm_sec);
	printk("tm_min : %i\n",dt->tm_min);
	printk("tm_hour: %i\n",dt->tm_hour);
	printk("tm_mday: %i\n",dt->tm_mday);
	printk("tm_wday: %i\n",dt->tm_wday);
	printk("tm_year: %i\n",dt->tm_year);
#endif

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

	max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec));
	max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min));
	max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour));

	max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday));
	max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1));
	max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday));
	max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100));
	max6902_set_reg(dev, 0x13, 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, 0xF, 0x80);

	return 0;
}

static int max6902_read_time(struct device *dev, struct rtc_time *tm)
{
	return max6902_get_datetime(dev, tm);
}

static int max6902_set_time(struct device *dev, struct rtc_time *tm)
{
	return max6902_set_datetime(dev, tm);
}

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

static int __devinit max6902_probe(struct spi_device *spi)
{
	struct rtc_device *rtc;
	unsigned char tmp;
	struct max6902 *chip;
	int res;

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

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

	chip = kzalloc(sizeof *chip, GFP_KERNEL);
	if (!chip) {
		rtc_device_unregister(rtc);
		return -ENOMEM;
	}
	chip->rtc = rtc;
	dev_set_drvdata(&spi->dev, chip);

	res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
	if (res) {
		rtc_device_unregister(rtc);
		return res;
	}

	return 0;
}

static int __devexit max6902_remove(struct spi_device *spi)
{
	struct max6902 *chip = platform_get_drvdata(spi);
	struct rtc_device *rtc = chip->rtc;

	if (rtc)
		rtc_device_unregister(rtc);

	kfree(chip);

	return 0;
}

static struct spi_driver max6902_driver = {
	.driver = {
		.name 	= "max6902",
		.bus	= &spi_bus_type,
		.owner	= THIS_MODULE,
	},
	.probe 	= max6902_probe,
	.remove = __devexit_p(max6902_remove),
};

static __init int max6902_init(void)
{
	printk("max6902 spi driver\n");
	return spi_register_driver(&max6902_driver);
}
module_init(max6902_init);

static __exit void max6902_exit(void)
{
	spi_unregister_driver(&max6902_driver);
}
module_exit(max6902_exit);

MODULE_DESCRIPTION ("max6902 spi RTC driver");
MODULE_AUTHOR ("Raphael Assenat");
MODULE_LICENSE ("GPL");