summaryrefslogtreecommitdiffstats
path: root/drivers/rtc/rtc-rx4581.c
blob: 84eb08d65d3053ee200bfec8d6736d1456518d5b (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
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
/* drivers/rtc/rtc-rx4581.c
 *
 * written by Torben Hohn <torbenh@linutronix.de>
 *
 * Based on:
 * 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
 *
 * and based on:
 * drivers/rtc/rtc-rx8581.c
 *
 * An I2C driver for the Epson RX8581 RTC
 *
 * Author: Martyn Welch <martyn.welch@ge.com>
 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
 *
 * 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.
 *
 * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
 * Copyright 2005-06 Tower Technologies
 *
 */

#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 RX4581_REG_SC		0x00 /* Second in BCD */
#define RX4581_REG_MN		0x01 /* Minute in BCD */
#define RX4581_REG_HR		0x02 /* Hour in BCD */
#define RX4581_REG_DW		0x03 /* Day of Week */
#define RX4581_REG_DM		0x04 /* Day of Month in BCD */
#define RX4581_REG_MO		0x05 /* Month in BCD */
#define RX4581_REG_YR		0x06 /* Year in BCD */
#define RX4581_REG_RAM		0x07 /* RAM */
#define RX4581_REG_AMN		0x08 /* Alarm Min in BCD*/
#define RX4581_REG_AHR		0x09 /* Alarm Hour in BCD */
#define RX4581_REG_ADM		0x0A
#define RX4581_REG_ADW		0x0A
#define RX4581_REG_TMR0		0x0B
#define RX4581_REG_TMR1		0x0C
#define RX4581_REG_EXT		0x0D /* Extension Register */
#define RX4581_REG_FLAG		0x0E /* Flag Register */
#define RX4581_REG_CTRL		0x0F /* Control Register */


/* Flag Register bit definitions */
#define RX4581_FLAG_UF		0x20 /* Update */
#define RX4581_FLAG_TF		0x10 /* Timer */
#define RX4581_FLAG_AF		0x08 /* Alarm */
#define RX4581_FLAG_VLF		0x02 /* Voltage Low */

/* Control Register bit definitions */
#define RX4581_CTRL_UIE		0x20 /* Update Interrupt Enable */
#define RX4581_CTRL_TIE		0x10 /* Timer Interrupt Enable */
#define RX4581_CTRL_AIE		0x08 /* Alarm Interrupt Enable */
#define RX4581_CTRL_STOP	0x02 /* STOP bit */
#define RX4581_CTRL_RESET	0x01 /* RESET bit */

static int rx4581_set_reg(struct device *dev, unsigned char address,
				unsigned char data)
{
	struct spi_device *spi = to_spi_device(dev);
	unsigned char buf[2];

	/* high nibble must be '0' to write */
	buf[0] = address & 0x0f;
	buf[1] = data;

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

static int rx4581_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);
}

/*
 * In the routines that deal directly with the rx8581 hardware, we use
 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 */
static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
{
	struct spi_device *spi = to_spi_device(dev);
	unsigned char date[7];
	unsigned char data;
	int err;

	/* First we ensure that the "update flag" is not set, we read the
	 * time and date then re-read the "update flag". If the update flag
	 * has been set, we know that the time has changed during the read so
	 * we repeat the whole process again.
	 */
	err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
	if (err != 0) {
		dev_err(dev, "Unable to read device flags\n");
		return -EIO;
	}

	do {
		/* If update flag set, clear it */
		if (data & RX4581_FLAG_UF) {
			err = rx4581_set_reg(dev,
				RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
			if (err != 0) {
				dev_err(dev, "Unable to write device "
					"flags\n");
				return -EIO;
			}
		}

		/* Now read time and date */
		date[0] = 0x80;
		err = spi_write_then_read(spi, date, 1, date, 7);
		if (err < 0) {
			dev_err(dev, "Unable to read date\n");
			return -EIO;
		}

		/* Check flag register */
		err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
		if (err != 0) {
			dev_err(dev, "Unable to read device flags\n");
			return -EIO;
		}
	} while (data & RX4581_FLAG_UF);

	if (data & RX4581_FLAG_VLF)
		dev_info(dev,
			"low voltage detected, date/time is not reliable.\n");

	dev_dbg(dev,
		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
		__func__,
		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);

	tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F);
	tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
	tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */
	tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F);
	tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F);
	tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
	tm->tm_year = bcd2bin(date[RX4581_REG_YR]);
	if (tm->tm_year < 70)
		tm->tm_year += 100;	/* assume we are in 1970...2069 */


	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
		"mday=%d, mon=%d, year=%d, wday=%d\n",
		__func__,
		tm->tm_sec, tm->tm_min, tm->tm_hour,
		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	err = rtc_valid_tm(tm);
	if (err < 0)
		dev_err(dev, "retrieved date/time is not valid.\n");

	return err;
}

static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
{
	struct spi_device *spi = to_spi_device(dev);
	int err;
	unsigned char buf[8], data;

	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
		"mday=%d, mon=%d, year=%d, wday=%d\n",
		__func__,
		tm->tm_sec, tm->tm_min, tm->tm_hour,
		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	buf[0] = 0x00;
	/* hours, minutes and seconds */
	buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
	buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
	buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);

	buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);

	/* month, 1 - 12 */
	buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);

	/* year and century */
	buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
	buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);

	/* Stop the clock */
	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
	if (err != 0) {
		dev_err(dev, "Unable to read control register\n");
		return -EIO;
	}

	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
		(data | RX4581_CTRL_STOP));
	if (err != 0) {
		dev_err(dev, "Unable to write control register\n");
		return -EIO;
	}

	/* write register's data */
	err = spi_write_then_read(spi, buf, 8, NULL, 0);
	if (err != 0) {
		dev_err(dev, "Unable to write to date registers\n");
		return -EIO;
	}

	/* get VLF and clear it */
	err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
	if (err != 0) {
		dev_err(dev, "Unable to read flag register\n");
		return -EIO;
	}

	err = rx4581_set_reg(dev, RX4581_REG_FLAG,
		(data & ~(RX4581_FLAG_VLF)));
	if (err != 0) {
		dev_err(dev, "Unable to write flag register\n");
		return -EIO;
	}

	/* Restart the clock */
	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
	if (err != 0) {
		dev_err(dev, "Unable to read control register\n");
		return -EIO;
	}

	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
		(data & ~(RX4581_CTRL_STOP)));
	if (err != 0) {
		dev_err(dev, "Unable to write control register\n");
		return -EIO;
	}

	return 0;
}

static const struct rtc_class_ops rx4581_rtc_ops = {
	.read_time	= rx4581_get_datetime,
	.set_time	= rx4581_set_datetime,
};

static int rx4581_probe(struct spi_device *spi)
{
	struct rtc_device *rtc;
	unsigned char tmp;
	int res;

	res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
	if (res != 0)
		return res;

	rtc = devm_rtc_device_register(&spi->dev, "rx4581",
				&rx4581_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	spi_set_drvdata(spi, rtc);
	return 0;
}

static int rx4581_remove(struct spi_device *spi)
{
	return 0;
}

static const struct spi_device_id rx4581_id[] = {
	{ "rx4581", 0 },
	{ }
};
MODULE_DEVICE_TABLE(spi, rx4581_id);

static struct spi_driver rx4581_driver = {
	.driver = {
		.name	= "rtc-rx4581",
		.owner	= THIS_MODULE,
	},
	.probe	= rx4581_probe,
	.remove = rx4581_remove,
	.id_table = rx4581_id,
};

module_spi_driver(rx4581_driver);

MODULE_DESCRIPTION("rx4581 spi RTC driver");
MODULE_AUTHOR("Torben Hohn");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-rx4581");
OpenPOWER on IntegriCloud