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>
23 #define M48T86_SEC 0x00
24 #define M48T86_SECALRM 0x01
25 #define M48T86_MIN 0x02
26 #define M48T86_MINALRM 0x03
27 #define M48T86_HOUR 0x04
28 #define M48T86_HOURALRM 0x05
29 #define M48T86_DOW 0x06 /* 1 = sunday */
30 #define M48T86_DOM 0x07
31 #define M48T86_MONTH 0x08 /* 1 - 12 */
32 #define M48T86_YEAR 0x09 /* 0 - 99 */
35 #define M48T86_B_SET BIT(7)
36 #define M48T86_B_DM BIT(2)
37 #define M48T86_B_H24 BIT(1)
40 #define M48T86_D_VRT BIT(7)
42 struct m48t86_rtc_info {
43 void __iomem *index_reg;
44 void __iomem *data_reg;
45 struct rtc_device *rtc;
46 struct m48t86_ops *ops;
49 static unsigned char m48t86_readb(struct device *dev, unsigned long addr)
51 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
55 value = info->ops->readbyte(addr);
57 writeb(addr, info->index_reg);
58 value = readb(info->data_reg);
63 static void m48t86_writeb(struct device *dev,
64 unsigned char value, unsigned long addr)
66 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
69 info->ops->writebyte(value, addr);
71 writeb(addr, info->index_reg);
72 writeb(value, info->data_reg);
76 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
80 reg = m48t86_readb(dev, M48T86_B);
82 if (reg & M48T86_B_DM) {
83 /* data (binary) mode */
84 tm->tm_sec = m48t86_readb(dev, M48T86_SEC);
85 tm->tm_min = m48t86_readb(dev, M48T86_MIN);
86 tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f;
87 tm->tm_mday = m48t86_readb(dev, M48T86_DOM);
89 tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1;
90 tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100;
91 tm->tm_wday = m48t86_readb(dev, M48T86_DOW);
94 tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC));
95 tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN));
96 tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) &
98 tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM));
100 tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;
101 tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100;
102 tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW));
105 /* correct the hour if the clock is in 12h mode */
106 if (!(reg & M48T86_B_H24))
107 if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
110 return rtc_valid_tm(tm);
113 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
117 reg = m48t86_readb(dev, M48T86_B);
119 /* update flag and 24h mode */
120 reg |= M48T86_B_SET | M48T86_B_H24;
121 m48t86_writeb(dev, reg, M48T86_B);
123 if (reg & M48T86_B_DM) {
124 /* data (binary) mode */
125 m48t86_writeb(dev, tm->tm_sec, M48T86_SEC);
126 m48t86_writeb(dev, tm->tm_min, M48T86_MIN);
127 m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR);
128 m48t86_writeb(dev, tm->tm_mday, M48T86_DOM);
129 m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
130 m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR);
131 m48t86_writeb(dev, tm->tm_wday, M48T86_DOW);
134 m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC);
135 m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN);
136 m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR);
137 m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM);
138 m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
139 m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR);
140 m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW);
144 reg &= ~M48T86_B_SET;
145 m48t86_writeb(dev, reg, M48T86_B);
150 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
154 reg = m48t86_readb(dev, M48T86_B);
156 seq_printf(seq, "mode\t\t: %s\n",
157 (reg & M48T86_B_DM) ? "binary" : "bcd");
159 reg = m48t86_readb(dev, M48T86_D);
161 seq_printf(seq, "battery\t\t: %s\n",
162 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
167 static const struct rtc_class_ops m48t86_rtc_ops = {
168 .read_time = m48t86_rtc_read_time,
169 .set_time = m48t86_rtc_set_time,
170 .proc = m48t86_rtc_proc,
173 static int m48t86_rtc_probe(struct platform_device *pdev)
175 struct m48t86_rtc_info *info;
178 info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
182 info->ops = dev_get_platdata(&pdev->dev);
184 struct resource *res;
186 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
189 info->index_reg = devm_ioremap_resource(&pdev->dev, res);
190 if (IS_ERR(info->index_reg))
191 return PTR_ERR(info->index_reg);
193 res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
196 info->data_reg = devm_ioremap_resource(&pdev->dev, res);
197 if (IS_ERR(info->data_reg))
198 return PTR_ERR(info->data_reg);
201 dev_set_drvdata(&pdev->dev, info);
203 info->rtc = devm_rtc_device_register(&pdev->dev, "m48t86",
204 &m48t86_rtc_ops, THIS_MODULE);
205 if (IS_ERR(info->rtc))
206 return PTR_ERR(info->rtc);
208 /* read battery status */
209 reg = m48t86_readb(&pdev->dev, M48T86_D);
210 dev_info(&pdev->dev, "battery %s\n",
211 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
216 static struct platform_driver m48t86_rtc_platform_driver = {
218 .name = "rtc-m48t86",
220 .probe = m48t86_rtc_probe,
223 module_platform_driver(m48t86_rtc_platform_driver);
225 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
226 MODULE_DESCRIPTION("M48T86 RTC driver");
227 MODULE_LICENSE("GPL");
228 MODULE_ALIAS("platform:rtc-m48t86");