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/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 
42 #define DRV_VERSION "0.1"
43 
44 
m48t86_rtc_read_time(struct device * dev,struct rtc_time * tm)45 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
46 {
47 	unsigned char reg;
48 	struct platform_device *pdev = to_platform_device(dev);
49 	struct m48t86_ops *ops = pdev->dev.platform_data;
50 
51 	reg = ops->readbyte(M48T86_REG_B);
52 
53 	if (reg & M48T86_REG_B_DM) {
54 		/* data (binary) mode */
55 		tm->tm_sec	= ops->readbyte(M48T86_REG_SEC);
56 		tm->tm_min	= ops->readbyte(M48T86_REG_MIN);
57 		tm->tm_hour	= ops->readbyte(M48T86_REG_HOUR) & 0x3F;
58 		tm->tm_mday	= ops->readbyte(M48T86_REG_DOM);
59 		/* tm_mon is 0-11 */
60 		tm->tm_mon	= ops->readbyte(M48T86_REG_MONTH) - 1;
61 		tm->tm_year	= ops->readbyte(M48T86_REG_YEAR) + 100;
62 		tm->tm_wday	= ops->readbyte(M48T86_REG_DOW);
63 	} else {
64 		/* bcd mode */
65 		tm->tm_sec	= bcd2bin(ops->readbyte(M48T86_REG_SEC));
66 		tm->tm_min	= bcd2bin(ops->readbyte(M48T86_REG_MIN));
67 		tm->tm_hour	= bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
68 		tm->tm_mday	= bcd2bin(ops->readbyte(M48T86_REG_DOM));
69 		/* tm_mon is 0-11 */
70 		tm->tm_mon	= bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
71 		tm->tm_year	= bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
72 		tm->tm_wday	= bcd2bin(ops->readbyte(M48T86_REG_DOW));
73 	}
74 
75 	/* correct the hour if the clock is in 12h mode */
76 	if (!(reg & M48T86_REG_B_H24))
77 		if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
78 			tm->tm_hour += 12;
79 
80 	return rtc_valid_tm(tm);
81 }
82 
m48t86_rtc_set_time(struct device * dev,struct rtc_time * tm)83 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
84 {
85 	unsigned char reg;
86 	struct platform_device *pdev = to_platform_device(dev);
87 	struct m48t86_ops *ops = pdev->dev.platform_data;
88 
89 	reg = ops->readbyte(M48T86_REG_B);
90 
91 	/* update flag and 24h mode */
92 	reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
93 	ops->writebyte(reg, M48T86_REG_B);
94 
95 	if (reg & M48T86_REG_B_DM) {
96 		/* data (binary) mode */
97 		ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
98 		ops->writebyte(tm->tm_min, M48T86_REG_MIN);
99 		ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
100 		ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
101 		ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
102 		ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
103 		ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
104 	} else {
105 		/* bcd mode */
106 		ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
107 		ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
108 		ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
109 		ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
110 		ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
111 		ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
112 		ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
113 	}
114 
115 	/* update ended */
116 	reg &= ~M48T86_REG_B_SET;
117 	ops->writebyte(reg, M48T86_REG_B);
118 
119 	return 0;
120 }
121 
m48t86_rtc_proc(struct device * dev,struct seq_file * seq)122 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
123 {
124 	unsigned char reg;
125 	struct platform_device *pdev = to_platform_device(dev);
126 	struct m48t86_ops *ops = pdev->dev.platform_data;
127 
128 	reg = ops->readbyte(M48T86_REG_B);
129 
130 	seq_printf(seq, "mode\t\t: %s\n",
131 		 (reg & M48T86_REG_B_DM) ? "binary" : "bcd");
132 
133 	reg = ops->readbyte(M48T86_REG_D);
134 
135 	seq_printf(seq, "battery\t\t: %s\n",
136 		 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
137 
138 	return 0;
139 }
140 
141 static const struct rtc_class_ops m48t86_rtc_ops = {
142 	.read_time	= m48t86_rtc_read_time,
143 	.set_time	= m48t86_rtc_set_time,
144 	.proc		= m48t86_rtc_proc,
145 };
146 
m48t86_rtc_probe(struct platform_device * dev)147 static int __devinit m48t86_rtc_probe(struct platform_device *dev)
148 {
149 	unsigned char reg;
150 	struct m48t86_ops *ops = dev->dev.platform_data;
151 	struct rtc_device *rtc = rtc_device_register("m48t86",
152 				&dev->dev, &m48t86_rtc_ops, THIS_MODULE);
153 
154 	if (IS_ERR(rtc))
155 		return PTR_ERR(rtc);
156 
157 	platform_set_drvdata(dev, rtc);
158 
159 	/* read battery status */
160 	reg = ops->readbyte(M48T86_REG_D);
161 	dev_info(&dev->dev, "battery %s\n",
162 		(reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
163 
164 	return 0;
165 }
166 
m48t86_rtc_remove(struct platform_device * dev)167 static int __devexit m48t86_rtc_remove(struct platform_device *dev)
168 {
169 	struct rtc_device *rtc = platform_get_drvdata(dev);
170 
171  	if (rtc)
172 		rtc_device_unregister(rtc);
173 
174 	platform_set_drvdata(dev, NULL);
175 
176 	return 0;
177 }
178 
179 static struct platform_driver m48t86_rtc_platform_driver = {
180 	.driver		= {
181 		.name	= "rtc-m48t86",
182 		.owner	= THIS_MODULE,
183 	},
184 	.probe		= m48t86_rtc_probe,
185 	.remove		= __devexit_p(m48t86_rtc_remove),
186 };
187 
188 module_platform_driver(m48t86_rtc_platform_driver);
189 
190 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
191 MODULE_DESCRIPTION("M48T86 RTC driver");
192 MODULE_LICENSE("GPL");
193 MODULE_VERSION(DRV_VERSION);
194 MODULE_ALIAS("platform:rtc-m48t86");
195