Linux 2.6.34-rc3
[pohmelfs.git] / drivers / rtc / rtc-ds1742.c
blobcad9ceb89bafea483c0cdbf0de70742bde2bb220
1 /*
2 * An rtc driver for the Dallas DS1742
4 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>
11 * - nvram size determined from resource
12 * - this ds1742 driver now supports ds1743.
15 #include <linux/bcd.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/delay.h>
19 #include <linux/jiffies.h>
20 #include <linux/rtc.h>
21 #include <linux/platform_device.h>
22 #include <linux/io.h>
24 #define DRV_VERSION "0.4"
26 #define RTC_SIZE 8
28 #define RTC_CONTROL 0
29 #define RTC_CENTURY 0
30 #define RTC_SECONDS 1
31 #define RTC_MINUTES 2
32 #define RTC_HOURS 3
33 #define RTC_DAY 4
34 #define RTC_DATE 5
35 #define RTC_MONTH 6
36 #define RTC_YEAR 7
38 #define RTC_CENTURY_MASK 0x3f
39 #define RTC_SECONDS_MASK 0x7f
40 #define RTC_DAY_MASK 0x07
42 /* Bits in the Control/Century register */
43 #define RTC_WRITE 0x80
44 #define RTC_READ 0x40
46 /* Bits in the Seconds register */
47 #define RTC_STOP 0x80
49 /* Bits in the Day register */
50 #define RTC_BATT_FLAG 0x80
52 struct rtc_plat_data {
53 struct rtc_device *rtc;
54 void __iomem *ioaddr_nvram;
55 void __iomem *ioaddr_rtc;
56 size_t size_nvram;
57 size_t size;
58 unsigned long last_jiffies;
59 struct bin_attribute nvram_attr;
62 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
64 struct platform_device *pdev = to_platform_device(dev);
65 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
66 void __iomem *ioaddr = pdata->ioaddr_rtc;
67 u8 century;
69 century = bin2bcd((tm->tm_year + 1900) / 100);
71 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
73 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
74 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
75 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
76 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
77 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
78 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
79 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
81 /* RTC_CENTURY and RTC_CONTROL share same register */
82 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
83 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
84 return 0;
87 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
89 struct platform_device *pdev = to_platform_device(dev);
90 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
91 void __iomem *ioaddr = pdata->ioaddr_rtc;
92 unsigned int year, month, day, hour, minute, second, week;
93 unsigned int century;
95 /* give enough time to update RTC in case of continuous read */
96 if (pdata->last_jiffies == jiffies)
97 msleep(1);
98 pdata->last_jiffies = jiffies;
99 writeb(RTC_READ, ioaddr + RTC_CONTROL);
100 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
101 minute = readb(ioaddr + RTC_MINUTES);
102 hour = readb(ioaddr + RTC_HOURS);
103 day = readb(ioaddr + RTC_DATE);
104 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
105 month = readb(ioaddr + RTC_MONTH);
106 year = readb(ioaddr + RTC_YEAR);
107 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
108 writeb(0, ioaddr + RTC_CONTROL);
109 tm->tm_sec = bcd2bin(second);
110 tm->tm_min = bcd2bin(minute);
111 tm->tm_hour = bcd2bin(hour);
112 tm->tm_mday = bcd2bin(day);
113 tm->tm_wday = bcd2bin(week);
114 tm->tm_mon = bcd2bin(month) - 1;
115 /* year is 1900 + tm->tm_year */
116 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
118 if (rtc_valid_tm(tm) < 0) {
119 dev_err(dev, "retrieved date/time is not valid.\n");
120 rtc_time_to_tm(0, tm);
122 return 0;
125 static const struct rtc_class_ops ds1742_rtc_ops = {
126 .read_time = ds1742_rtc_read_time,
127 .set_time = ds1742_rtc_set_time,
130 static ssize_t ds1742_nvram_read(struct kobject *kobj,
131 struct bin_attribute *bin_attr,
132 char *buf, loff_t pos, size_t size)
134 struct device *dev = container_of(kobj, struct device, kobj);
135 struct platform_device *pdev = to_platform_device(dev);
136 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
137 void __iomem *ioaddr = pdata->ioaddr_nvram;
138 ssize_t count;
140 for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
141 *buf++ = readb(ioaddr + pos++);
142 return count;
145 static ssize_t ds1742_nvram_write(struct kobject *kobj,
146 struct bin_attribute *bin_attr,
147 char *buf, loff_t pos, size_t size)
149 struct device *dev = container_of(kobj, struct device, kobj);
150 struct platform_device *pdev = to_platform_device(dev);
151 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
152 void __iomem *ioaddr = pdata->ioaddr_nvram;
153 ssize_t count;
155 for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
156 writeb(*buf++, ioaddr + pos++);
157 return count;
160 static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
162 struct rtc_device *rtc;
163 struct resource *res;
164 unsigned int cen, sec;
165 struct rtc_plat_data *pdata;
166 void __iomem *ioaddr;
167 int ret = 0;
169 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
170 if (!res)
171 return -ENODEV;
172 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
173 if (!pdata)
174 return -ENOMEM;
175 pdata->size = res->end - res->start + 1;
176 if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
177 pdev->name))
178 return -EBUSY;
179 ioaddr = devm_ioremap(&pdev->dev, res->start, pdata->size);
180 if (!ioaddr)
181 return -ENOMEM;
183 pdata->ioaddr_nvram = ioaddr;
184 pdata->size_nvram = pdata->size - RTC_SIZE;
185 pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
187 sysfs_bin_attr_init(&pdata->nvram_attr);
188 pdata->nvram_attr.attr.name = "nvram";
189 pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
190 pdata->nvram_attr.read = ds1742_nvram_read;
191 pdata->nvram_attr.write = ds1742_nvram_write;
192 pdata->nvram_attr.size = pdata->size_nvram;
194 /* turn RTC on if it was not on */
195 ioaddr = pdata->ioaddr_rtc;
196 sec = readb(ioaddr + RTC_SECONDS);
197 if (sec & RTC_STOP) {
198 sec &= RTC_SECONDS_MASK;
199 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
200 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
201 writeb(sec, ioaddr + RTC_SECONDS);
202 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
204 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
205 dev_warn(&pdev->dev, "voltage-low detected.\n");
207 pdata->last_jiffies = jiffies;
208 platform_set_drvdata(pdev, pdata);
209 rtc = rtc_device_register(pdev->name, &pdev->dev,
210 &ds1742_rtc_ops, THIS_MODULE);
211 if (IS_ERR(rtc))
212 return PTR_ERR(rtc);
213 pdata->rtc = rtc;
215 ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
216 if (ret) {
217 dev_err(&pdev->dev, "creating nvram file in sysfs failed\n");
218 rtc_device_unregister(rtc);
220 return ret;
223 static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
225 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
227 sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
228 rtc_device_unregister(pdata->rtc);
229 return 0;
232 static struct platform_driver ds1742_rtc_driver = {
233 .probe = ds1742_rtc_probe,
234 .remove = __devexit_p(ds1742_rtc_remove),
235 .driver = {
236 .name = "rtc-ds1742",
237 .owner = THIS_MODULE,
241 static __init int ds1742_init(void)
243 return platform_driver_register(&ds1742_rtc_driver);
246 static __exit void ds1742_exit(void)
248 platform_driver_unregister(&ds1742_rtc_driver);
251 module_init(ds1742_init);
252 module_exit(ds1742_exit);
254 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
255 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
256 MODULE_LICENSE("GPL");
257 MODULE_VERSION(DRV_VERSION);
258 MODULE_ALIAS("platform:rtc-ds1742");