2 * ST M48T86 / Dallas DS12887 RTC driver
3 * Copyright (c) 2006 Tower Technologies
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
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.
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.
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>
22 #define M48T86_SEC 0x00
23 #define M48T86_SECALRM 0x01
24 #define M48T86_MIN 0x02
25 #define M48T86_MINALRM 0x03
26 #define M48T86_HOUR 0x04
27 #define M48T86_HOURALRM 0x05
28 #define M48T86_DOW 0x06 /* 1 = sunday */
29 #define M48T86_DOM 0x07
30 #define M48T86_MONTH 0x08 /* 1 - 12 */
31 #define M48T86_YEAR 0x09 /* 0 - 99 */
34 #define M48T86_B_SET BIT(7)
35 #define M48T86_B_DM BIT(2)
36 #define M48T86_B_H24 BIT(1)
39 #define M48T86_D_VRT BIT(7)
41 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
44 struct platform_device *pdev = to_platform_device(dev);
45 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
47 reg = ops->readbyte(M48T86_B);
49 if (reg & M48T86_B_DM) {
50 /* data (binary) mode */
51 tm->tm_sec = ops->readbyte(M48T86_SEC);
52 tm->tm_min = ops->readbyte(M48T86_MIN);
53 tm->tm_hour = ops->readbyte(M48T86_HOUR) & 0x3f;
54 tm->tm_mday = ops->readbyte(M48T86_DOM);
56 tm->tm_mon = ops->readbyte(M48T86_MONTH) - 1;
57 tm->tm_year = ops->readbyte(M48T86_YEAR) + 100;
58 tm->tm_wday = ops->readbyte(M48T86_DOW);
61 tm->tm_sec = bcd2bin(ops->readbyte(M48T86_SEC));
62 tm->tm_min = bcd2bin(ops->readbyte(M48T86_MIN));
63 tm->tm_hour = bcd2bin(ops->readbyte(M48T86_HOUR) & 0x3f);
64 tm->tm_mday = bcd2bin(ops->readbyte(M48T86_DOM));
66 tm->tm_mon = bcd2bin(ops->readbyte(M48T86_MONTH)) - 1;
67 tm->tm_year = bcd2bin(ops->readbyte(M48T86_YEAR)) + 100;
68 tm->tm_wday = bcd2bin(ops->readbyte(M48T86_DOW));
71 /* correct the hour if the clock is in 12h mode */
72 if (!(reg & M48T86_B_H24))
73 if (ops->readbyte(M48T86_HOUR) & 0x80)
76 return rtc_valid_tm(tm);
79 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
82 struct platform_device *pdev = to_platform_device(dev);
83 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
85 reg = ops->readbyte(M48T86_B);
87 /* update flag and 24h mode */
88 reg |= M48T86_B_SET | M48T86_B_H24;
89 ops->writebyte(reg, M48T86_B);
91 if (reg & M48T86_B_DM) {
92 /* data (binary) mode */
93 ops->writebyte(tm->tm_sec, M48T86_SEC);
94 ops->writebyte(tm->tm_min, M48T86_MIN);
95 ops->writebyte(tm->tm_hour, M48T86_HOUR);
96 ops->writebyte(tm->tm_mday, M48T86_DOM);
97 ops->writebyte(tm->tm_mon + 1, M48T86_MONTH);
98 ops->writebyte(tm->tm_year % 100, M48T86_YEAR);
99 ops->writebyte(tm->tm_wday, M48T86_DOW);
102 ops->writebyte(bin2bcd(tm->tm_sec), M48T86_SEC);
103 ops->writebyte(bin2bcd(tm->tm_min), M48T86_MIN);
104 ops->writebyte(bin2bcd(tm->tm_hour), M48T86_HOUR);
105 ops->writebyte(bin2bcd(tm->tm_mday), M48T86_DOM);
106 ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
107 ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_YEAR);
108 ops->writebyte(bin2bcd(tm->tm_wday), M48T86_DOW);
112 reg &= ~M48T86_B_SET;
113 ops->writebyte(reg, M48T86_B);
118 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
121 struct platform_device *pdev = to_platform_device(dev);
122 struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
124 reg = ops->readbyte(M48T86_B);
126 seq_printf(seq, "mode\t\t: %s\n",
127 (reg & M48T86_B_DM) ? "binary" : "bcd");
129 reg = ops->readbyte(M48T86_D);
131 seq_printf(seq, "battery\t\t: %s\n",
132 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
137 static const struct rtc_class_ops m48t86_rtc_ops = {
138 .read_time = m48t86_rtc_read_time,
139 .set_time = m48t86_rtc_set_time,
140 .proc = m48t86_rtc_proc,
143 static int m48t86_rtc_probe(struct platform_device *dev)
146 struct m48t86_ops *ops = dev_get_platdata(&dev->dev);
147 struct rtc_device *rtc;
149 rtc = devm_rtc_device_register(&dev->dev, "m48t86",
150 &m48t86_rtc_ops, THIS_MODULE);
155 platform_set_drvdata(dev, rtc);
157 /* read battery status */
158 reg = ops->readbyte(M48T86_D);
159 dev_info(&dev->dev, "battery %s\n",
160 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
165 static struct platform_driver m48t86_rtc_platform_driver = {
167 .name = "rtc-m48t86",
169 .probe = m48t86_rtc_probe,
172 module_platform_driver(m48t86_rtc_platform_driver);
174 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
175 MODULE_DESCRIPTION("M48T86 RTC driver");
176 MODULE_LICENSE("GPL");
177 MODULE_ALIAS("platform:rtc-m48t86");