UPSTREAM Revert 3.9 "rtc: palmas: Add RTC driver Palmas series PMIC"
[linux-3.10.git] / drivers / rtc / rtc-m41t94.c
1 /*
2  * Driver for ST M41T94 SPI RTC
3  *
4  * Copyright (C) 2008 Kim B. Heino
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/platform_device.h>
14 #include <linux/rtc.h>
15 #include <linux/spi/spi.h>
16 #include <linux/bcd.h>
17
18 #define M41T94_REG_SECONDS      0x01
19 #define M41T94_REG_MINUTES      0x02
20 #define M41T94_REG_HOURS        0x03
21 #define M41T94_REG_WDAY         0x04
22 #define M41T94_REG_DAY          0x05
23 #define M41T94_REG_MONTH        0x06
24 #define M41T94_REG_YEAR         0x07
25 #define M41T94_REG_HT           0x0c
26
27 #define M41T94_BIT_HALT         0x40
28 #define M41T94_BIT_STOP         0x80
29 #define M41T94_BIT_CB           0x40
30 #define M41T94_BIT_CEB          0x80
31
32 static int m41t94_set_time(struct device *dev, struct rtc_time *tm)
33 {
34         struct spi_device *spi = to_spi_device(dev);
35         u8 buf[8]; /* write cmd + 7 registers */
36
37         dev_dbg(dev, "%s secs=%d, mins=%d, "
38                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
39                 "write", tm->tm_sec, tm->tm_min,
40                 tm->tm_hour, tm->tm_mday,
41                 tm->tm_mon, tm->tm_year, tm->tm_wday);
42
43         buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
44         buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
45         buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
46         buf[M41T94_REG_HOURS]   = bin2bcd(tm->tm_hour);
47         buf[M41T94_REG_WDAY]    = bin2bcd(tm->tm_wday + 1);
48         buf[M41T94_REG_DAY]     = bin2bcd(tm->tm_mday);
49         buf[M41T94_REG_MONTH]   = bin2bcd(tm->tm_mon + 1);
50
51         buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
52         if (tm->tm_year >= 100)
53                 buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
54         buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);
55
56         return spi_write(spi, buf, 8);
57 }
58
59 static int m41t94_read_time(struct device *dev, struct rtc_time *tm)
60 {
61         struct spi_device *spi = to_spi_device(dev);
62         u8 buf[2];
63         int ret, hour;
64
65         /* clear halt update bit */
66         ret = spi_w8r8(spi, M41T94_REG_HT);
67         if (ret < 0)
68                 return ret;
69         if (ret & M41T94_BIT_HALT) {
70                 buf[0] = 0x80 | M41T94_REG_HT;
71                 buf[1] = ret & ~M41T94_BIT_HALT;
72                 spi_write(spi, buf, 2);
73         }
74
75         /* clear stop bit */
76         ret = spi_w8r8(spi, M41T94_REG_SECONDS);
77         if (ret < 0)
78                 return ret;
79         if (ret & M41T94_BIT_STOP) {
80                 buf[0] = 0x80 | M41T94_REG_SECONDS;
81                 buf[1] = ret & ~M41T94_BIT_STOP;
82                 spi_write(spi, buf, 2);
83         }
84
85         tm->tm_sec  = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS));
86         tm->tm_min  = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES));
87         hour = spi_w8r8(spi, M41T94_REG_HOURS);
88         tm->tm_hour = bcd2bin(hour & 0x3f);
89         tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1;
90         tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY));
91         tm->tm_mon  = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1;
92         tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR));
93         if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
94                 tm->tm_year += 100;
95
96         dev_dbg(dev, "%s secs=%d, mins=%d, "
97                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
98                 "read", tm->tm_sec, tm->tm_min,
99                 tm->tm_hour, tm->tm_mday,
100                 tm->tm_mon, tm->tm_year, tm->tm_wday);
101
102         /* initial clock setting can be undefined */
103         return rtc_valid_tm(tm);
104 }
105
106 static const struct rtc_class_ops m41t94_rtc_ops = {
107         .read_time      = m41t94_read_time,
108         .set_time       = m41t94_set_time,
109 };
110
111 static struct spi_driver m41t94_driver;
112
113 static int m41t94_probe(struct spi_device *spi)
114 {
115         struct rtc_device *rtc;
116         int res;
117
118         spi->bits_per_word = 8;
119         spi_setup(spi);
120
121         res = spi_w8r8(spi, M41T94_REG_SECONDS);
122         if (res < 0) {
123                 dev_err(&spi->dev, "not found.\n");
124                 return res;
125         }
126
127         rtc = devm_rtc_device_register(&spi->dev, m41t94_driver.driver.name,
128                                         &m41t94_rtc_ops, THIS_MODULE);
129         if (IS_ERR(rtc))
130                 return PTR_ERR(rtc);
131
132         spi_set_drvdata(spi, rtc);
133
134         return 0;
135 }
136
137 static int m41t94_remove(struct spi_device *spi)
138 {
139         return 0;
140 }
141
142 static struct spi_driver m41t94_driver = {
143         .driver = {
144                 .name   = "rtc-m41t94",
145                 .owner  = THIS_MODULE,
146         },
147         .probe  = m41t94_probe,
148         .remove = m41t94_remove,
149 };
150
151 module_spi_driver(m41t94_driver);
152
153 MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>");
154 MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC");
155 MODULE_LICENSE("GPL");
156 MODULE_ALIAS("spi:rtc-m41t94");