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
45static 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 = dev_get_platdata(&pdev->dev);
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
83static 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 = dev_get_platdata(&pdev->dev);
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
122static 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 = dev_get_platdata(&pdev->dev);
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
141static 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
147static int m48t86_rtc_probe(struct platform_device *dev)
148{
149	unsigned char reg;
150	struct m48t86_ops *ops = dev_get_platdata(&dev->dev);
151	struct rtc_device *rtc;
152
153	rtc = devm_rtc_device_register(&dev->dev, "m48t86",
154				&m48t86_rtc_ops, THIS_MODULE);
155
156	if (IS_ERR(rtc))
157		return PTR_ERR(rtc);
158
159	platform_set_drvdata(dev, rtc);
160
161	/* read battery status */
162	reg = ops->readbyte(M48T86_REG_D);
163	dev_info(&dev->dev, "battery %s\n",
164		(reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
165
166	return 0;
167}
168
169static struct platform_driver m48t86_rtc_platform_driver = {
170	.driver		= {
171		.name	= "rtc-m48t86",
172	},
173	.probe		= m48t86_rtc_probe,
174};
175
176module_platform_driver(m48t86_rtc_platform_driver);
177
178MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
179MODULE_DESCRIPTION("M48T86 RTC driver");
180MODULE_LICENSE("GPL");
181MODULE_VERSION(DRV_VERSION);
182MODULE_ALIAS("platform:rtc-m48t86");
183