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
write_reg(struct device * dev,int address,unsigned char data)43 static 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
read_regs(struct device * dev,unsigned char * regs,int no_regs)54 static 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
r9701_get_datetime(struct device * dev,struct rtc_time * dt)71 static 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 0;
96 }
97
r9701_set_datetime(struct device * dev,struct rtc_time * dt)98 static 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
117 static const struct rtc_class_ops r9701_rtc_ops = {
118 .read_time = r9701_get_datetime,
119 .set_time = r9701_set_datetime,
120 };
121
r9701_probe(struct spi_device * spi)122 static int 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 = devm_rtc_device_register(&spi->dev, "r9701",
158 &r9701_rtc_ops, THIS_MODULE);
159 if (IS_ERR(rtc))
160 return PTR_ERR(rtc);
161
162 spi_set_drvdata(spi, rtc);
163
164 return 0;
165 }
166
167 static struct spi_driver r9701_driver = {
168 .driver = {
169 .name = "rtc-r9701",
170 },
171 .probe = r9701_probe,
172 };
173
174 module_spi_driver(r9701_driver);
175
176 MODULE_DESCRIPTION("r9701 spi RTC driver");
177 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
178 MODULE_LICENSE("GPL");
179 MODULE_ALIAS("spi:rtc-r9701");
180