[PATCH] RTC: add rtc-ds1742 driver

[Atsushi Nemoto <anemo@mba.ocn.ne.jp>]

Add an RTC driver for the Dallas DS1742 RTC chip.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 65d090d..2a5eab0 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -96,6 +96,16 @@ config RTC_DRV_DS1672
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-ds1672.
 
+config RTC_DRV_DS1742
+	tristate "Dallas DS1742"
+	depends on RTC_CLASS
+	help
+	  If you say yes here you get support for the
+	  Dallas DS1742 timekeeping chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-ds1742.
+
 config RTC_DRV_PCF8563
 	tristate "Philips PCF8563/Epson RTC8564"
 	depends on RTC_CLASS && I2C
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index a9ca0f1..6226cae 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_RTC_INTF_DEV)	+= rtc-dev.o
 obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
 obj-$(CONFIG_RTC_DRV_TEST)	+= rtc-test.o
 obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
+obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o
 obj-$(CONFIG_RTC_DRV_PCF8563)	+= rtc-pcf8563.o
 obj-$(CONFIG_RTC_DRV_RS5C372)	+= rtc-rs5c372.o
 obj-$(CONFIG_RTC_DRV_M48T86)	+= rtc-m48t86.o
diff --git a/drivers/rtc/rtc-ds1742.c b/drivers/rtc/rtc-ds1742.c
new file mode 100644
index 0000000..41b03a0
--- /dev/null
+++ b/drivers/rtc/rtc-ds1742.c
@@ -0,0 +1,260 @@
+/*
+ * 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>
+
+#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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