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path: root/drivers/rtc/rtc-ds1742.c
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-rw-r--r--drivers/rtc/rtc-ds1742.c259
1 files changed, 259 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1742.c b/drivers/rtc/rtc-ds1742.c
new file mode 100644
index 000000000000..8e47e5a06d2a
--- /dev/null
+++ b/drivers/rtc/rtc-ds1742.c
@@ -0,0 +1,259 @@
1/*
2 * An rtc driver for the Dallas DS1742
3 *
4 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
5 *
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.
9 */
10
11#include <linux/bcd.h>
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/delay.h>
15#include <linux/jiffies.h>
16#include <linux/rtc.h>
17#include <linux/platform_device.h>
18#include <linux/io.h>
19
20#define DRV_VERSION "0.1"
21
22#define RTC_REG_SIZE 0x800
23#define RTC_OFFSET 0x7f8
24
25#define RTC_CONTROL (RTC_OFFSET + 0)
26#define RTC_CENTURY (RTC_OFFSET + 0)
27#define RTC_SECONDS (RTC_OFFSET + 1)
28#define RTC_MINUTES (RTC_OFFSET + 2)
29#define RTC_HOURS (RTC_OFFSET + 3)
30#define RTC_DAY (RTC_OFFSET + 4)
31#define RTC_DATE (RTC_OFFSET + 5)
32#define RTC_MONTH (RTC_OFFSET + 6)
33#define RTC_YEAR (RTC_OFFSET + 7)
34
35#define RTC_CENTURY_MASK 0x3f
36#define RTC_SECONDS_MASK 0x7f
37#define RTC_DAY_MASK 0x07
38
39/* Bits in the Control/Century register */
40#define RTC_WRITE 0x80
41#define RTC_READ 0x40
42
43/* Bits in the Seconds register */
44#define RTC_STOP 0x80
45
46/* Bits in the Day register */
47#define RTC_BATT_FLAG 0x80
48
49struct rtc_plat_data {
50 struct rtc_device *rtc;
51 void __iomem *ioaddr;
52 unsigned long baseaddr;
53 unsigned long last_jiffies;
54};
55
56static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
57{
58 struct platform_device *pdev = to_platform_device(dev);
59 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
60 void __iomem *ioaddr = pdata->ioaddr;
61 u8 century;
62
63 century = BIN2BCD((tm->tm_year + 1900) / 100);
64
65 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
66
67 writeb(BIN2BCD(tm->tm_year % 100), ioaddr + RTC_YEAR);
68 writeb(BIN2BCD(tm->tm_mon + 1), ioaddr + RTC_MONTH);
69 writeb(BIN2BCD(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
70 writeb(BIN2BCD(tm->tm_mday), ioaddr + RTC_DATE);
71 writeb(BIN2BCD(tm->tm_hour), ioaddr + RTC_HOURS);
72 writeb(BIN2BCD(tm->tm_min), ioaddr + RTC_MINUTES);
73 writeb(BIN2BCD(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
74
75 /* RTC_CENTURY and RTC_CONTROL share same register */
76 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
77 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
78 return 0;
79}
80
81static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
82{
83 struct platform_device *pdev = to_platform_device(dev);
84 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
85 void __iomem *ioaddr = pdata->ioaddr;
86 unsigned int year, month, day, hour, minute, second, week;
87 unsigned int century;
88
89 /* give enough time to update RTC in case of continuous read */
90 if (pdata->last_jiffies == jiffies)
91 msleep(1);
92 pdata->last_jiffies = jiffies;
93 writeb(RTC_READ, ioaddr + RTC_CONTROL);
94 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
95 minute = readb(ioaddr + RTC_MINUTES);
96 hour = readb(ioaddr + RTC_HOURS);
97 day = readb(ioaddr + RTC_DATE);
98 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
99 month = readb(ioaddr + RTC_MONTH);
100 year = readb(ioaddr + RTC_YEAR);
101 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
102 writeb(0, ioaddr + RTC_CONTROL);
103 tm->tm_sec = BCD2BIN(second);
104 tm->tm_min = BCD2BIN(minute);
105 tm->tm_hour = BCD2BIN(hour);
106 tm->tm_mday = BCD2BIN(day);
107 tm->tm_wday = BCD2BIN(week);
108 tm->tm_mon = BCD2BIN(month) - 1;
109 /* year is 1900 + tm->tm_year */
110 tm->tm_year = BCD2BIN(year) + BCD2BIN(century) * 100 - 1900;
111
112 if (rtc_valid_tm(tm) < 0) {
113 dev_err(dev, "retrieved date/time is not valid.\n");
114 rtc_time_to_tm(0, tm);
115 }
116 return 0;
117}
118
119static struct rtc_class_ops ds1742_rtc_ops = {
120 .read_time = ds1742_rtc_read_time,
121 .set_time = ds1742_rtc_set_time,
122};
123
124static ssize_t ds1742_nvram_read(struct kobject *kobj, char *buf,
125 loff_t pos, size_t size)
126{
127 struct platform_device *pdev =
128 to_platform_device(container_of(kobj, struct device, kobj));
129 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
130 void __iomem *ioaddr = pdata->ioaddr;
131 ssize_t count;
132
133 for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
134 *buf++ = readb(ioaddr + pos++);
135 return count;
136}
137
138static ssize_t ds1742_nvram_write(struct kobject *kobj, char *buf,
139 loff_t pos, size_t size)
140{
141 struct platform_device *pdev =
142 to_platform_device(container_of(kobj, struct device, kobj));
143 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
144 void __iomem *ioaddr = pdata->ioaddr;
145 ssize_t count;
146
147 for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
148 writeb(*buf++, ioaddr + pos++);
149 return count;
150}
151
152static struct bin_attribute ds1742_nvram_attr = {
153 .attr = {
154 .name = "nvram",
155 .mode = S_IRUGO | S_IWUGO,
156 .owner = THIS_MODULE,
157 },
158 .size = RTC_OFFSET,
159 .read = ds1742_nvram_read,
160 .write = ds1742_nvram_write,
161};
162
163static int __init ds1742_rtc_probe(struct platform_device *pdev)
164{
165 struct rtc_device *rtc;
166 struct resource *res;
167 unsigned int cen, sec;
168 struct rtc_plat_data *pdata = NULL;
169 void __iomem *ioaddr = NULL;
170 int ret = 0;
171
172 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
173 if (!res)
174 return -ENODEV;
175 pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
176 if (!pdata)
177 return -ENOMEM;
178 if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) {
179 ret = -EBUSY;
180 goto out;
181 }
182 pdata->baseaddr = res->start;
183 ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE);
184 if (!ioaddr) {
185 ret = -ENOMEM;
186 goto out;
187 }
188 pdata->ioaddr = ioaddr;
189
190 /* turn RTC on if it was not on */
191 sec = readb(ioaddr + RTC_SECONDS);
192 if (sec & RTC_STOP) {
193 sec &= RTC_SECONDS_MASK;
194 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
195 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
196 writeb(sec, ioaddr + RTC_SECONDS);
197 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
198 }
199 if (readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)
200 dev_warn(&pdev->dev, "voltage-low detected.\n");
201
202 rtc = rtc_device_register(pdev->name, &pdev->dev,
203 &ds1742_rtc_ops, THIS_MODULE);
204 if (IS_ERR(rtc)) {
205 ret = PTR_ERR(rtc);
206 goto out;
207 }
208 pdata->rtc = rtc;
209 pdata->last_jiffies = jiffies;
210 platform_set_drvdata(pdev, pdata);
211 sysfs_create_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
212 return 0;
213 out:
214 if (ioaddr)
215 iounmap(ioaddr);
216 if (pdata->baseaddr)
217 release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
218 kfree(pdata);
219 return ret;
220}
221
222static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
223{
224 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
225
226 sysfs_remove_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
227 rtc_device_unregister(pdata->rtc);
228 iounmap(pdata->ioaddr);
229 release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
230 kfree(pdata);
231 return 0;
232}
233
234static struct platform_driver ds1742_rtc_driver = {
235 .probe = ds1742_rtc_probe,
236 .remove = __devexit_p(ds1742_rtc_remove),
237 .driver = {
238 .name = "ds1742",
239 .owner = THIS_MODULE,
240 },
241};
242
243static __init int ds1742_init(void)
244{
245 return platform_driver_register(&ds1742_rtc_driver);
246}
247
248static __exit void ds1742_exit(void)
249{
250 return platform_driver_unregister(&ds1742_rtc_driver);
251}
252
253module_init(ds1742_init);
254module_exit(ds1742_exit);
255
256MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
257MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
258MODULE_LICENSE("GPL");
259MODULE_VERSION(DRV_VERSION);