1 /*
2 * ST M48T86 / Dallas DS12887 RTC driver
3 * Copyright (c) 2006 Tower Technologies
4 *
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This drivers only supports the clock running in BCD and 24H mode.
12 * If it will be ever adapted to binary and 12H mode, care must be taken
13 * to not introduce bugs.
14 */
15
16 #include <linux/module.h>
17 #include <linux/rtc.h>
18 #include <linux/platform_device.h>
19 #include <linux/platform_data/rtc-m48t86.h>
20 #include <linux/bcd.h>
21
22 #define M48T86_REG_SEC 0x00
23 #define M48T86_REG_SECALRM 0x01
24 #define M48T86_REG_MIN 0x02
25 #define M48T86_REG_MINALRM 0x03
26 #define M48T86_REG_HOUR 0x04
27 #define M48T86_REG_HOURALRM 0x05
28 #define M48T86_REG_DOW 0x06 /* 1 = sunday */
29 #define M48T86_REG_DOM 0x07
30 #define M48T86_REG_MONTH 0x08 /* 1 - 12 */
31 #define M48T86_REG_YEAR 0x09 /* 0 - 99 */
32 #define M48T86_REG_A 0x0A
33 #define M48T86_REG_B 0x0B
34 #define M48T86_REG_C 0x0C
35 #define M48T86_REG_D 0x0D
36
37 #define M48T86_REG_B_H24 (1 << 1)
38 #define M48T86_REG_B_DM (1 << 2)
39 #define M48T86_REG_B_SET (1 << 7)
40 #define M48T86_REG_D_VRT (1 << 7)
41
m48t86_rtc_read_time(struct device * dev,struct rtc_time * tm)42 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
43 {
44 unsigned char reg;
45 struct platform_device *pdev = to_platform_device(dev);
46 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
47
48 reg = ops->readbyte(M48T86_REG_B);
49
50 if (reg & M48T86_REG_B_DM) {
51 /* data (binary) mode */
52 tm->tm_sec = ops->readbyte(M48T86_REG_SEC);
53 tm->tm_min = ops->readbyte(M48T86_REG_MIN);
54 tm->tm_hour = ops->readbyte(M48T86_REG_HOUR) & 0x3F;
55 tm->tm_mday = ops->readbyte(M48T86_REG_DOM);
56 /* tm_mon is 0-11 */
57 tm->tm_mon = ops->readbyte(M48T86_REG_MONTH) - 1;
58 tm->tm_year = ops->readbyte(M48T86_REG_YEAR) + 100;
59 tm->tm_wday = ops->readbyte(M48T86_REG_DOW);
60 } else {
61 /* bcd mode */
62 tm->tm_sec = bcd2bin(ops->readbyte(M48T86_REG_SEC));
63 tm->tm_min = bcd2bin(ops->readbyte(M48T86_REG_MIN));
64 tm->tm_hour = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
65 tm->tm_mday = bcd2bin(ops->readbyte(M48T86_REG_DOM));
66 /* tm_mon is 0-11 */
67 tm->tm_mon = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
68 tm->tm_year = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
69 tm->tm_wday = bcd2bin(ops->readbyte(M48T86_REG_DOW));
70 }
71
72 /* correct the hour if the clock is in 12h mode */
73 if (!(reg & M48T86_REG_B_H24))
74 if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
75 tm->tm_hour += 12;
76
77 return rtc_valid_tm(tm);
78 }
79
m48t86_rtc_set_time(struct device * dev,struct rtc_time * tm)80 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
81 {
82 unsigned char reg;
83 struct platform_device *pdev = to_platform_device(dev);
84 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
85
86 reg = ops->readbyte(M48T86_REG_B);
87
88 /* update flag and 24h mode */
89 reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
90 ops->writebyte(reg, M48T86_REG_B);
91
92 if (reg & M48T86_REG_B_DM) {
93 /* data (binary) mode */
94 ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
95 ops->writebyte(tm->tm_min, M48T86_REG_MIN);
96 ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
97 ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
98 ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
99 ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
100 ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
101 } else {
102 /* bcd mode */
103 ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
104 ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
105 ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
106 ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
107 ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
108 ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
109 ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
110 }
111
112 /* update ended */
113 reg &= ~M48T86_REG_B_SET;
114 ops->writebyte(reg, M48T86_REG_B);
115
116 return 0;
117 }
118
m48t86_rtc_proc(struct device * dev,struct seq_file * seq)119 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
120 {
121 unsigned char reg;
122 struct platform_device *pdev = to_platform_device(dev);
123 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
124
125 reg = ops->readbyte(M48T86_REG_B);
126
127 seq_printf(seq, "mode\t\t: %s\n",
128 (reg & M48T86_REG_B_DM) ? "binary" : "bcd");
129
130 reg = ops->readbyte(M48T86_REG_D);
131
132 seq_printf(seq, "battery\t\t: %s\n",
133 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
134
135 return 0;
136 }
137
138 static const struct rtc_class_ops m48t86_rtc_ops = {
139 .read_time = m48t86_rtc_read_time,
140 .set_time = m48t86_rtc_set_time,
141 .proc = m48t86_rtc_proc,
142 };
143
m48t86_rtc_probe(struct platform_device * dev)144 static int m48t86_rtc_probe(struct platform_device *dev)
145 {
146 unsigned char reg;
147 struct m48t86_ops *ops = dev_get_platdata(&dev->dev);
148 struct rtc_device *rtc;
149
150 rtc = devm_rtc_device_register(&dev->dev, "m48t86",
151 &m48t86_rtc_ops, THIS_MODULE);
152
153 if (IS_ERR(rtc))
154 return PTR_ERR(rtc);
155
156 platform_set_drvdata(dev, rtc);
157
158 /* read battery status */
159 reg = ops->readbyte(M48T86_REG_D);
160 dev_info(&dev->dev, "battery %s\n",
161 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
162
163 return 0;
164 }
165
166 static struct platform_driver m48t86_rtc_platform_driver = {
167 .driver = {
168 .name = "rtc-m48t86",
169 },
170 .probe = m48t86_rtc_probe,
171 };
172
173 module_platform_driver(m48t86_rtc_platform_driver);
174
175 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
176 MODULE_DESCRIPTION("M48T86 RTC driver");
177 MODULE_LICENSE("GPL");
178 MODULE_ALIAS("platform:rtc-m48t86");
179