Root/drivers/rtc/rtc-r9701.c

1/*
2 * Driver for Epson RTC-9701JE
3 *
4 * Copyright (C) 2008 Magnus Damm
5 *
6 * Based on rtc-max6902.c
7 *
8 * Copyright (C) 2006 8D Technologies inc.
9 * Copyright (C) 2004 Compulab Ltd.
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#include <linux/module.h>
17#include <linux/kernel.h>
18#include <linux/platform_device.h>
19#include <linux/device.h>
20#include <linux/init.h>
21#include <linux/rtc.h>
22#include <linux/spi/spi.h>
23#include <linux/bcd.h>
24#include <linux/delay.h>
25#include <linux/bitops.h>
26
27#define RSECCNT 0x00 /* Second Counter */
28#define RMINCNT 0x01 /* Minute Counter */
29#define RHRCNT 0x02 /* Hour Counter */
30#define RWKCNT 0x03 /* Week Counter */
31#define RDAYCNT 0x04 /* Day Counter */
32#define RMONCNT 0x05 /* Month Counter */
33#define RYRCNT 0x06 /* Year Counter */
34#define R100CNT 0x07 /* Y100 Counter */
35#define RMINAR 0x08 /* Minute Alarm */
36#define RHRAR 0x09 /* Hour Alarm */
37#define RWKAR 0x0a /* Week/Day Alarm */
38#define RTIMCNT 0x0c /* Interval Timer */
39#define REXT 0x0d /* Extension Register */
40#define RFLAG 0x0e /* RTC Flag Register */
41#define RCR 0x0f /* RTC Control Register */
42
43static int write_reg(struct device *dev, int address, unsigned char data)
44{
45    struct spi_device *spi = to_spi_device(dev);
46    unsigned char buf[2];
47
48    buf[0] = address & 0x7f;
49    buf[1] = data;
50
51    return spi_write(spi, buf, ARRAY_SIZE(buf));
52}
53
54static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
55{
56    struct spi_device *spi = to_spi_device(dev);
57    u8 txbuf[1], rxbuf[1];
58    int k, ret;
59
60    ret = 0;
61
62    for (k = 0; ret == 0 && k < no_regs; k++) {
63        txbuf[0] = 0x80 | regs[k];
64        ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
65        regs[k] = rxbuf[0];
66    }
67
68    return ret;
69}
70
71static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
72{
73    int ret;
74    unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
75                RDAYCNT, RMONCNT, RYRCNT };
76
77    ret = read_regs(dev, buf, ARRAY_SIZE(buf));
78    if (ret)
79        return ret;
80
81    memset(dt, 0, sizeof(*dt));
82
83    dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
84    dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
85    dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
86
87    dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
88    dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
89    dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
90
91    /* the rtc device may contain illegal values on power up
92     * according to the data sheet. make sure they are valid.
93     */
94
95    return rtc_valid_tm(dt);
96}
97
98static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
99{
100    int ret, year;
101
102    year = dt->tm_year + 1900;
103    if (year >= 2100 || year < 2000)
104        return -EINVAL;
105
106    ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
107    ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
108    ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
109    ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
110    ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
111    ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
112    ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday);
113
114    return ret;
115}
116
117static const struct rtc_class_ops r9701_rtc_ops = {
118    .read_time = r9701_get_datetime,
119    .set_time = r9701_set_datetime,
120};
121
122static int __devinit r9701_probe(struct spi_device *spi)
123{
124    struct rtc_device *rtc;
125    struct rtc_time dt;
126    unsigned char tmp;
127    int res;
128
129    tmp = R100CNT;
130    res = read_regs(&spi->dev, &tmp, 1);
131    if (res || tmp != 0x20) {
132        dev_err(&spi->dev, "cannot read RTC register\n");
133        return -ENODEV;
134    }
135
136    /*
137     * The device seems to be present. Now check if the registers
138     * contain invalid values. If so, try to write a default date:
139     * 2000/1/1 00:00:00
140     */
141    if (r9701_get_datetime(&spi->dev, &dt)) {
142        dev_info(&spi->dev, "trying to repair invalid date/time\n");
143        dt.tm_sec = 0;
144        dt.tm_min = 0;
145        dt.tm_hour = 0;
146        dt.tm_mday = 1;
147        dt.tm_mon = 0;
148        dt.tm_year = 100;
149
150        if (r9701_set_datetime(&spi->dev, &dt) ||
151                r9701_get_datetime(&spi->dev, &dt)) {
152            dev_err(&spi->dev, "cannot repair RTC register\n");
153            return -ENODEV;
154        }
155    }
156
157    rtc = rtc_device_register("r9701",
158                &spi->dev, &r9701_rtc_ops, THIS_MODULE);
159    if (IS_ERR(rtc))
160        return PTR_ERR(rtc);
161
162    dev_set_drvdata(&spi->dev, rtc);
163
164    return 0;
165}
166
167static int __devexit r9701_remove(struct spi_device *spi)
168{
169    struct rtc_device *rtc = dev_get_drvdata(&spi->dev);
170
171    rtc_device_unregister(rtc);
172    return 0;
173}
174
175static struct spi_driver r9701_driver = {
176    .driver = {
177        .name = "rtc-r9701",
178        .owner = THIS_MODULE,
179    },
180    .probe = r9701_probe,
181    .remove = __devexit_p(r9701_remove),
182};
183
184module_spi_driver(r9701_driver);
185
186MODULE_DESCRIPTION("r9701 spi RTC driver");
187MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
188MODULE_LICENSE("GPL");
189MODULE_ALIAS("spi:rtc-r9701");
190

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