[PATCH] RTC: add rtc-ds1742 driver

Add an RTC driver for the Dallas DS1742 RTC chip.

[akpm@osdl.org: cleanups, compile fix]
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

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 @@
+/*
+ * 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);