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/*
* An rtc driver for the Dallas DS1742
*
* Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/bcd.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#define DRV_VERSION "0.1"
#define RTC_REG_SIZE 0x800
#define RTC_OFFSET 0x7f8
#define RTC_CONTROL (RTC_OFFSET + 0)
#define RTC_CENTURY (RTC_OFFSET + 0)
#define RTC_SECONDS (RTC_OFFSET + 1)
#define RTC_MINUTES (RTC_OFFSET + 2)
#define RTC_HOURS (RTC_OFFSET + 3)
#define RTC_DAY (RTC_OFFSET + 4)
#define RTC_DATE (RTC_OFFSET + 5)
#define RTC_MONTH (RTC_OFFSET + 6)
#define RTC_YEAR (RTC_OFFSET + 7)
#define RTC_CENTURY_MASK 0x3f
#define RTC_SECONDS_MASK 0x7f
#define RTC_DAY_MASK 0x07
/* Bits in the Control/Century register */
#define RTC_WRITE 0x80
#define RTC_READ 0x40
/* Bits in the Seconds register */
#define RTC_STOP 0x80
/* Bits in the Day register */
#define RTC_BATT_FLAG 0x80
struct rtc_plat_data {
struct rtc_device *rtc;
void __iomem *ioaddr;
unsigned long baseaddr;
unsigned long last_jiffies;
};
static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
u8 century;
century = BIN2BCD((tm->tm_year + 1900) / 100);
writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
writeb(BIN2BCD(tm->tm_year % 100), ioaddr + RTC_YEAR);
writeb(BIN2BCD(tm->tm_mon + 1), ioaddr + RTC_MONTH);
writeb(BIN2BCD(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
writeb(BIN2BCD(tm->tm_mday), ioaddr + RTC_DATE);
writeb(BIN2BCD(tm->tm_hour), ioaddr + RTC_HOURS);
writeb(BIN2BCD(tm->tm_min), ioaddr + RTC_MINUTES);
writeb(BIN2BCD(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
/* RTC_CENTURY and RTC_CONTROL share same register */
writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
return 0;
}
static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct platform_device *pdev = to_platform_device(dev);
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
unsigned int year, month, day, hour, minute, second, week;
unsigned int century;
/* give enough time to update RTC in case of continuous read */
if (pdata->last_jiffies == jiffies)
msleep(1);
pdata->last_jiffies = jiffies;
writeb(RTC_READ, ioaddr + RTC_CONTROL);
second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
minute = readb(ioaddr + RTC_MINUTES);
hour = readb(ioaddr + RTC_HOURS);
day = readb(ioaddr + RTC_DATE);
week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
month = readb(ioaddr + RTC_MONTH);
year = readb(ioaddr + RTC_YEAR);
century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
writeb(0, ioaddr + RTC_CONTROL);
tm->tm_sec = BCD2BIN(second);
tm->tm_min = BCD2BIN(minute);
tm->tm_hour = BCD2BIN(hour);
tm->tm_mday = BCD2BIN(day);
tm->tm_wday = BCD2BIN(week);
tm->tm_mon = BCD2BIN(month) - 1;
/* year is 1900 + tm->tm_year */
tm->tm_year = BCD2BIN(year) + BCD2BIN(century) * 100 - 1900;
if (rtc_valid_tm(tm) < 0) {
dev_err(dev, "retrieved date/time is not valid.\n");
rtc_time_to_tm(0, tm);
}
return 0;
}
static struct rtc_class_ops ds1742_rtc_ops = {
.read_time = ds1742_rtc_read_time,
.set_time = ds1742_rtc_set_time,
};
static ssize_t ds1742_nvram_read(struct kobject *kobj, char *buf,
loff_t pos, size_t size)
{
struct platform_device *pdev =
to_platform_device(container_of(kobj, struct device, kobj));
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
ssize_t count;
for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
*buf++ = readb(ioaddr + pos++);
return count;
}
static ssize_t ds1742_nvram_write(struct kobject *kobj, char *buf,
loff_t pos, size_t size)
{
struct platform_device *pdev =
to_platform_device(container_of(kobj, struct device, kobj));
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
void __iomem *ioaddr = pdata->ioaddr;
ssize_t count;
for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
writeb(*buf++, ioaddr + pos++);
return count;
}
static struct bin_attribute ds1742_nvram_attr = {
.attr = {
.name = "nvram",
.mode = S_IRUGO | S_IWUGO,
.owner = THIS_MODULE,
},
.size = RTC_OFFSET,
.read = ds1742_nvram_read,
.write = ds1742_nvram_write,
};
static int __init ds1742_rtc_probe(struct platform_device *pdev)
{
struct rtc_device *rtc;
struct resource *res;
unsigned int cen, sec;
struct rtc_plat_data *pdata = NULL;
void __iomem *ioaddr = NULL;
int ret = 0;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) {
ret = -EBUSY;
goto out;
}
pdata->baseaddr = res->start;
ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE);
if (!ioaddr) {
ret = -ENOMEM;
goto out;
}
pdata->ioaddr = ioaddr;
/* turn RTC on if it was not on */
sec = readb(ioaddr + RTC_SECONDS);
if (sec & RTC_STOP) {
sec &= RTC_SECONDS_MASK;
cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
writeb(sec, ioaddr + RTC_SECONDS);
writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
}
if (readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG)
dev_warn(&pdev->dev, "voltage-low detected.\n");
rtc = rtc_device_register(pdev->name, &pdev->dev,
&ds1742_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc)) {
ret = PTR_ERR(rtc);
goto out;
}
pdata->rtc = rtc;
pdata->last_jiffies = jiffies;
platform_set_drvdata(pdev, pdata);
sysfs_create_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
return 0;
out:
if (ioaddr)
iounmap(ioaddr);
if (pdata->baseaddr)
release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
kfree(pdata);
return ret;
}
static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
{
struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
sysfs_remove_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
rtc_device_unregister(pdata->rtc);
iounmap(pdata->ioaddr);
release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
kfree(pdata);
return 0;
}
static struct platform_driver ds1742_rtc_driver = {
.probe = ds1742_rtc_probe,
.remove = __devexit_p(ds1742_rtc_remove),
.driver = {
.name = "ds1742",
.owner = THIS_MODULE,
},
};
static __init int ds1742_init(void)
{
return platform_driver_register(&ds1742_rtc_driver);
}
static __exit void ds1742_exit(void)
{
return platform_driver_unregister(&ds1742_rtc_driver);
}
module_init(ds1742_init);
module_exit(ds1742_exit);
MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
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