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Linux/drivers/rtc/rtc-ds1742.c

  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  * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>
 11  *  - nvram size determined from resource
 12  *  - this ds1742 driver now supports ds1743.
 13  */
 14 
 15 #include <linux/bcd.h>
 16 #include <linux/kernel.h>
 17 #include <linux/gfp.h>
 18 #include <linux/delay.h>
 19 #include <linux/jiffies.h>
 20 #include <linux/rtc.h>
 21 #include <linux/of.h>
 22 #include <linux/of_device.h>
 23 #include <linux/platform_device.h>
 24 #include <linux/io.h>
 25 #include <linux/module.h>
 26 
 27 #define RTC_SIZE                8
 28 
 29 #define RTC_CONTROL             0
 30 #define RTC_CENTURY             0
 31 #define RTC_SECONDS             1
 32 #define RTC_MINUTES             2
 33 #define RTC_HOURS               3
 34 #define RTC_DAY                 4
 35 #define RTC_DATE                5
 36 #define RTC_MONTH               6
 37 #define RTC_YEAR                7
 38 
 39 #define RTC_CENTURY_MASK        0x3f
 40 #define RTC_SECONDS_MASK        0x7f
 41 #define RTC_DAY_MASK            0x07
 42 
 43 /* Bits in the Control/Century register */
 44 #define RTC_WRITE               0x80
 45 #define RTC_READ                0x40
 46 
 47 /* Bits in the Seconds register */
 48 #define RTC_STOP                0x80
 49 
 50 /* Bits in the Day register */
 51 #define RTC_BATT_FLAG           0x80
 52 
 53 struct rtc_plat_data {
 54         void __iomem *ioaddr_nvram;
 55         void __iomem *ioaddr_rtc;
 56         size_t size_nvram;
 57         unsigned long last_jiffies;
 58         struct bin_attribute nvram_attr;
 59 };
 60 
 61 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
 62 {
 63         struct platform_device *pdev = to_platform_device(dev);
 64         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 65         void __iomem *ioaddr = pdata->ioaddr_rtc;
 66         u8 century;
 67 
 68         century = bin2bcd((tm->tm_year + 1900) / 100);
 69 
 70         writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 71 
 72         writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
 73         writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
 74         writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
 75         writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
 76         writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
 77         writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
 78         writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
 79 
 80         /* RTC_CENTURY and RTC_CONTROL share same register */
 81         writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
 82         writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 83         return 0;
 84 }
 85 
 86 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
 87 {
 88         struct platform_device *pdev = to_platform_device(dev);
 89         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 90         void __iomem *ioaddr = pdata->ioaddr_rtc;
 91         unsigned int year, month, day, hour, minute, second, week;
 92         unsigned int century;
 93 
 94         /* give enough time to update RTC in case of continuous read */
 95         if (pdata->last_jiffies == jiffies)
 96                 msleep(1);
 97         pdata->last_jiffies = jiffies;
 98         writeb(RTC_READ, ioaddr + RTC_CONTROL);
 99         second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
100         minute = readb(ioaddr + RTC_MINUTES);
101         hour = readb(ioaddr + RTC_HOURS);
102         day = readb(ioaddr + RTC_DATE);
103         week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
104         month = readb(ioaddr + RTC_MONTH);
105         year = readb(ioaddr + RTC_YEAR);
106         century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
107         writeb(0, ioaddr + RTC_CONTROL);
108         tm->tm_sec = bcd2bin(second);
109         tm->tm_min = bcd2bin(minute);
110         tm->tm_hour = bcd2bin(hour);
111         tm->tm_mday = bcd2bin(day);
112         tm->tm_wday = bcd2bin(week);
113         tm->tm_mon = bcd2bin(month) - 1;
114         /* year is 1900 + tm->tm_year */
115         tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
116 
117         return rtc_valid_tm(tm);
118 }
119 
120 static const struct rtc_class_ops ds1742_rtc_ops = {
121         .read_time      = ds1742_rtc_read_time,
122         .set_time       = ds1742_rtc_set_time,
123 };
124 
125 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
126                                  struct bin_attribute *bin_attr,
127                                  char *buf, loff_t pos, size_t size)
128 {
129         struct device *dev = container_of(kobj, struct device, kobj);
130         struct platform_device *pdev = to_platform_device(dev);
131         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
132         void __iomem *ioaddr = pdata->ioaddr_nvram;
133         ssize_t count;
134 
135         for (count = 0; count < size; count++)
136                 *buf++ = readb(ioaddr + pos++);
137         return count;
138 }
139 
140 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
141                                   struct bin_attribute *bin_attr,
142                                   char *buf, loff_t pos, size_t size)
143 {
144         struct device *dev = container_of(kobj, struct device, kobj);
145         struct platform_device *pdev = to_platform_device(dev);
146         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
147         void __iomem *ioaddr = pdata->ioaddr_nvram;
148         ssize_t count;
149 
150         for (count = 0; count < size; count++)
151                 writeb(*buf++, ioaddr + pos++);
152         return count;
153 }
154 
155 static int ds1742_rtc_probe(struct platform_device *pdev)
156 {
157         struct rtc_device *rtc;
158         struct resource *res;
159         unsigned int cen, sec;
160         struct rtc_plat_data *pdata;
161         void __iomem *ioaddr;
162         int ret = 0;
163 
164         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
165         if (!pdata)
166                 return -ENOMEM;
167 
168         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
169         ioaddr = devm_ioremap_resource(&pdev->dev, res);
170         if (IS_ERR(ioaddr))
171                 return PTR_ERR(ioaddr);
172 
173         pdata->ioaddr_nvram = ioaddr;
174         pdata->size_nvram = resource_size(res) - RTC_SIZE;
175         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
176 
177         sysfs_bin_attr_init(&pdata->nvram_attr);
178         pdata->nvram_attr.attr.name = "nvram";
179         pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
180         pdata->nvram_attr.read = ds1742_nvram_read;
181         pdata->nvram_attr.write = ds1742_nvram_write;
182         pdata->nvram_attr.size = pdata->size_nvram;
183 
184         /* turn RTC on if it was not on */
185         ioaddr = pdata->ioaddr_rtc;
186         sec = readb(ioaddr + RTC_SECONDS);
187         if (sec & RTC_STOP) {
188                 sec &= RTC_SECONDS_MASK;
189                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
190                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
191                 writeb(sec, ioaddr + RTC_SECONDS);
192                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
193         }
194         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
195                 dev_warn(&pdev->dev, "voltage-low detected.\n");
196 
197         pdata->last_jiffies = jiffies;
198         platform_set_drvdata(pdev, pdata);
199         rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
200                                   &ds1742_rtc_ops, THIS_MODULE);
201         if (IS_ERR(rtc))
202                 return PTR_ERR(rtc);
203 
204         ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
205         if (ret)
206                 dev_err(&pdev->dev, "Unable to create sysfs entry: %s\n",
207                         pdata->nvram_attr.attr.name);
208 
209         return 0;
210 }
211 
212 static int ds1742_rtc_remove(struct platform_device *pdev)
213 {
214         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
215 
216         sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
217         return 0;
218 }
219 
220 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
221         { .compatible = "maxim,ds1742", },
222         { }
223 };
224 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
225 
226 static struct platform_driver ds1742_rtc_driver = {
227         .probe          = ds1742_rtc_probe,
228         .remove         = ds1742_rtc_remove,
229         .driver         = {
230                 .name   = "rtc-ds1742",
231                 .of_match_table = of_match_ptr(ds1742_rtc_of_match),
232         },
233 };
234 
235 module_platform_driver(ds1742_rtc_driver);
236 
237 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
238 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
239 MODULE_LICENSE("GPL");
240 MODULE_ALIAS("platform:rtc-ds1742");
241 

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