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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 DRV_VERSION "0.4"
 28 
 29 #define RTC_SIZE                8
 30 
 31 #define RTC_CONTROL             0
 32 #define RTC_CENTURY             0
 33 #define RTC_SECONDS             1
 34 #define RTC_MINUTES             2
 35 #define RTC_HOURS               3
 36 #define RTC_DAY                 4
 37 #define RTC_DATE                5
 38 #define RTC_MONTH               6
 39 #define RTC_YEAR                7
 40 
 41 #define RTC_CENTURY_MASK        0x3f
 42 #define RTC_SECONDS_MASK        0x7f
 43 #define RTC_DAY_MASK            0x07
 44 
 45 /* Bits in the Control/Century register */
 46 #define RTC_WRITE               0x80
 47 #define RTC_READ                0x40
 48 
 49 /* Bits in the Seconds register */
 50 #define RTC_STOP                0x80
 51 
 52 /* Bits in the Day register */
 53 #define RTC_BATT_FLAG           0x80
 54 
 55 struct rtc_plat_data {
 56         void __iomem *ioaddr_nvram;
 57         void __iomem *ioaddr_rtc;
 58         size_t size_nvram;
 59         unsigned long last_jiffies;
 60         struct bin_attribute nvram_attr;
 61 };
 62 
 63 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
 64 {
 65         struct platform_device *pdev = to_platform_device(dev);
 66         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 67         void __iomem *ioaddr = pdata->ioaddr_rtc;
 68         u8 century;
 69 
 70         century = bin2bcd((tm->tm_year + 1900) / 100);
 71 
 72         writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 73 
 74         writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
 75         writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
 76         writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
 77         writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
 78         writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
 79         writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
 80         writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
 81 
 82         /* RTC_CENTURY and RTC_CONTROL share same register */
 83         writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
 84         writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 85         return 0;
 86 }
 87 
 88 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
 89 {
 90         struct platform_device *pdev = to_platform_device(dev);
 91         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 92         void __iomem *ioaddr = pdata->ioaddr_rtc;
 93         unsigned int year, month, day, hour, minute, second, week;
 94         unsigned int century;
 95 
 96         /* give enough time to update RTC in case of continuous read */
 97         if (pdata->last_jiffies == jiffies)
 98                 msleep(1);
 99         pdata->last_jiffies = jiffies;
100         writeb(RTC_READ, ioaddr + RTC_CONTROL);
101         second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
102         minute = readb(ioaddr + RTC_MINUTES);
103         hour = readb(ioaddr + RTC_HOURS);
104         day = readb(ioaddr + RTC_DATE);
105         week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
106         month = readb(ioaddr + RTC_MONTH);
107         year = readb(ioaddr + RTC_YEAR);
108         century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
109         writeb(0, ioaddr + RTC_CONTROL);
110         tm->tm_sec = bcd2bin(second);
111         tm->tm_min = bcd2bin(minute);
112         tm->tm_hour = bcd2bin(hour);
113         tm->tm_mday = bcd2bin(day);
114         tm->tm_wday = bcd2bin(week);
115         tm->tm_mon = bcd2bin(month) - 1;
116         /* year is 1900 + tm->tm_year */
117         tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
118 
119         return rtc_valid_tm(tm);
120 }
121 
122 static const struct rtc_class_ops ds1742_rtc_ops = {
123         .read_time      = ds1742_rtc_read_time,
124         .set_time       = ds1742_rtc_set_time,
125 };
126 
127 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
128                                  struct bin_attribute *bin_attr,
129                                  char *buf, loff_t pos, size_t size)
130 {
131         struct device *dev = container_of(kobj, struct device, kobj);
132         struct platform_device *pdev = to_platform_device(dev);
133         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
134         void __iomem *ioaddr = pdata->ioaddr_nvram;
135         ssize_t count;
136 
137         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
138                 *buf++ = readb(ioaddr + pos++);
139         return count;
140 }
141 
142 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
143                                   struct bin_attribute *bin_attr,
144                                   char *buf, loff_t pos, size_t size)
145 {
146         struct device *dev = container_of(kobj, struct device, kobj);
147         struct platform_device *pdev = to_platform_device(dev);
148         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
149         void __iomem *ioaddr = pdata->ioaddr_nvram;
150         ssize_t count;
151 
152         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
153                 writeb(*buf++, ioaddr + pos++);
154         return count;
155 }
156 
157 static int ds1742_rtc_probe(struct platform_device *pdev)
158 {
159         struct rtc_device *rtc;
160         struct resource *res;
161         unsigned int cen, sec;
162         struct rtc_plat_data *pdata;
163         void __iomem *ioaddr;
164         int ret = 0;
165 
166         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
167         if (!pdata)
168                 return -ENOMEM;
169 
170         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
171         ioaddr = devm_ioremap_resource(&pdev->dev, res);
172         if (IS_ERR(ioaddr))
173                 return PTR_ERR(ioaddr);
174 
175         pdata->ioaddr_nvram = ioaddr;
176         pdata->size_nvram = resource_size(res) - RTC_SIZE;
177         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
178 
179         sysfs_bin_attr_init(&pdata->nvram_attr);
180         pdata->nvram_attr.attr.name = "nvram";
181         pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
182         pdata->nvram_attr.read = ds1742_nvram_read;
183         pdata->nvram_attr.write = ds1742_nvram_write;
184         pdata->nvram_attr.size = pdata->size_nvram;
185 
186         /* turn RTC on if it was not on */
187         ioaddr = pdata->ioaddr_rtc;
188         sec = readb(ioaddr + RTC_SECONDS);
189         if (sec & RTC_STOP) {
190                 sec &= RTC_SECONDS_MASK;
191                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
192                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
193                 writeb(sec, ioaddr + RTC_SECONDS);
194                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
195         }
196         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
197                 dev_warn(&pdev->dev, "voltage-low detected.\n");
198 
199         pdata->last_jiffies = jiffies;
200         platform_set_drvdata(pdev, pdata);
201         rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
202                                   &ds1742_rtc_ops, THIS_MODULE);
203         if (IS_ERR(rtc))
204                 return PTR_ERR(rtc);
205 
206         ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
207         if (ret)
208                 dev_err(&pdev->dev, "Unable to create sysfs entry: %s\n",
209                         pdata->nvram_attr.attr.name);
210 
211         return 0;
212 }
213 
214 static int ds1742_rtc_remove(struct platform_device *pdev)
215 {
216         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
217 
218         sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
219         return 0;
220 }
221 
222 static struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
223         { .compatible = "maxim,ds1742", },
224         { }
225 };
226 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
227 
228 static struct platform_driver ds1742_rtc_driver = {
229         .probe          = ds1742_rtc_probe,
230         .remove         = ds1742_rtc_remove,
231         .driver         = {
232                 .name   = "rtc-ds1742",
233                 .owner  = THIS_MODULE,
234                 .of_match_table = ds1742_rtc_of_match,
235         },
236 };
237 
238 module_platform_driver(ds1742_rtc_driver);
239 
240 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
241 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
242 MODULE_LICENSE("GPL");
243 MODULE_VERSION(DRV_VERSION);
244 MODULE_ALIAS("platform:rtc-ds1742");
245 

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