[PATCH] RTC subsystem: M48T86 driver

Add a driver for the ST M48T86 / Dallas DS12887 RTC.

This is a platform driver.  The platform device must provide I/O routines to
access the RTC.

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 236 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 166232a3f56b..929dd8090578 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -117,6 +117,16 @@ config RTC_DRV_RS5C372
           This driver can also be built as a module. If so, the module
           will be called rtc-rs5c372.
 
+config RTC_DRV_M48T86
+        tristate "ST M48T86/Dallas DS12887"
+        depends on RTC_CLASS
+        help
+          If you say Y here you will get support for the
+          ST M48T86 and Dallas DS12887 RTC chips.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-m48t86.
+
 config RTC_DRV_EP93XX
         tristate "Cirrus Logic EP93XX"
         depends on RTC_CLASS && ARCH_EP93XX
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 56820d18161e..8d4c7fe88d58 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -16,5 +16,6 @@ obj-$(CONFIG_RTC_DRV_TEST)	+= rtc-test.o
 obj-$(CONFIG_RTC_DRV_DS1672)    += rtc-ds1672.o
 obj-$(CONFIG_RTC_DRV_PCF8563)   += rtc-pcf8563.o
 obj-$(CONFIG_RTC_DRV_RS5C372)   += rtc-rs5c372.o
+obj-$(CONFIG_RTC_DRV_M48T86)    += rtc-m48t86.o
 obj-$(CONFIG_RTC_DRV_EP93XX)    += rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_SA1100)    += rtc-sa1100.o
diff --git a/drivers/rtc/rtc-m48t86.c b/drivers/rtc/rtc-m48t86.c
new file mode 100644
index 000000000000..db445c872b1b
--- /dev/null
+++ b/drivers/rtc/rtc-m48t86.c
@@ -0,0 +1,209 @@
+/*
+ * ST M48T86 / Dallas DS12887 RTC driver
+ * Copyright (c) 2006 Tower Technologies
+ *
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * 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.
+ *
+ * This drivers only supports the clock running in BCD and 24H mode.
+ * If it will be ever adapted to binary and 12H mode, care must be taken
+ * to not introduce bugs.
+ */
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+#include <linux/m48t86.h>
+#include <linux/bcd.h>
+
+#define M48T86_REG_SEC          0x00
+#define M48T86_REG_SECALRM      0x01
+#define M48T86_REG_MIN          0x02
+#define M48T86_REG_MINALRM      0x03
+#define M48T86_REG_HOUR 0x04
+#define M48T86_REG_HOURALRM     0x05
+#define M48T86_REG_DOW          0x06 /* 1 = sunday */
+#define M48T86_REG_DOM          0x07
+#define M48T86_REG_MONTH        0x08 /* 1 - 12 */
+#define M48T86_REG_YEAR         0x09 /* 0 - 99 */
+#define M48T86_REG_A            0x0A
+#define M48T86_REG_B            0x0B
+#define M48T86_REG_C            0x0C
+#define M48T86_REG_D            0x0D
+
+#define M48T86_REG_B_H24        (1 << 1)
+#define M48T86_REG_B_DM         (1 << 2)
+#define M48T86_REG_B_SET        (1 << 7)
+#define M48T86_REG_D_VRT        (1 << 7)
+
+#define DRV_VERSION "0.1"
+
+
+static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        unsigned char reg;
+        struct platform_device *pdev = to_platform_device(dev);
+        struct m48t86_ops *ops = pdev->dev.platform_data;
+
+        reg = ops->readb(M48T86_REG_B);
+
+        if (reg & M48T86_REG_B_DM) {
+                /* data (binary) mode */
+                tm->tm_sec      = ops->readb(M48T86_REG_SEC);
+                tm->tm_min      = ops->readb(M48T86_REG_MIN);
+                tm->tm_hour     = ops->readb(M48T86_REG_HOUR) & 0x3F;
+                tm->tm_mday     = ops->readb(M48T86_REG_DOM);
+                /* tm_mon is 0-11 */
+                tm->tm_mon      = ops->readb(M48T86_REG_MONTH) - 1;
+                tm->tm_year     = ops->readb(M48T86_REG_YEAR) + 100;
+                tm->tm_wday     = ops->readb(M48T86_REG_DOW);
+        } else {
+                /* bcd mode */
+                tm->tm_sec      = BCD2BIN(ops->readb(M48T86_REG_SEC));
+                tm->tm_min      = BCD2BIN(ops->readb(M48T86_REG_MIN));
+                tm->tm_hour     = BCD2BIN(ops->readb(M48T86_REG_HOUR) & 0x3F);
+                tm->tm_mday     = BCD2BIN(ops->readb(M48T86_REG_DOM));
+                /* tm_mon is 0-11 */
+                tm->tm_mon      = BCD2BIN(ops->readb(M48T86_REG_MONTH)) - 1;
+                tm->tm_year     = BCD2BIN(ops->readb(M48T86_REG_YEAR)) + 100;
+                tm->tm_wday     = BCD2BIN(ops->readb(M48T86_REG_DOW));
+        }
+
+        /* correct the hour if the clock is in 12h mode */
+        if (!(reg & M48T86_REG_B_H24))
+                if (ops->readb(M48T86_REG_HOUR) & 0x80)
+                        tm->tm_hour += 12;
+
+        return 0;
+}
+
+static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        unsigned char reg;
+        struct platform_device *pdev = to_platform_device(dev);
+        struct m48t86_ops *ops = pdev->dev.platform_data;
+
+        reg = ops->readb(M48T86_REG_B);
+
+        /* update flag and 24h mode */
+        reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
+        ops->writeb(reg, M48T86_REG_B);
+
+        if (reg & M48T86_REG_B_DM) {
+                /* data (binary) mode */
+                ops->writeb(tm->tm_sec, M48T86_REG_SEC);
+                ops->writeb(tm->tm_min, M48T86_REG_MIN);
+                ops->writeb(tm->tm_hour, M48T86_REG_HOUR);
+                ops->writeb(tm->tm_mday, M48T86_REG_DOM);
+                ops->writeb(tm->tm_mon + 1, M48T86_REG_MONTH);
+                ops->writeb(tm->tm_year % 100, M48T86_REG_YEAR);
+                ops->writeb(tm->tm_wday, M48T86_REG_DOW);
+        } else {
+                /* bcd mode */
+                ops->writeb(BIN2BCD(tm->tm_sec), M48T86_REG_SEC);
+                ops->writeb(BIN2BCD(tm->tm_min), M48T86_REG_MIN);
+                ops->writeb(BIN2BCD(tm->tm_hour), M48T86_REG_HOUR);
+                ops->writeb(BIN2BCD(tm->tm_mday), M48T86_REG_DOM);
+                ops->writeb(BIN2BCD(tm->tm_mon + 1), M48T86_REG_MONTH);
+                ops->writeb(BIN2BCD(tm->tm_year % 100), M48T86_REG_YEAR);
+                ops->writeb(BIN2BCD(tm->tm_wday), M48T86_REG_DOW);
+        }
+
+        /* update ended */
+        reg &= ~M48T86_REG_B_SET;
+        ops->writeb(reg, M48T86_REG_B);
+
+        return 0;
+}
+
+static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+        unsigned char reg;
+        struct platform_device *pdev = to_platform_device(dev);
+        struct m48t86_ops *ops = pdev->dev.platform_data;
+
+        reg = ops->readb(M48T86_REG_B);
+
+        seq_printf(seq, "24hr\t\t: %s\n",
+                 (reg & M48T86_REG_B_H24) ? "yes" : "no");
+
+        seq_printf(seq, "mode\t\t: %s\n",
+                 (reg & M48T86_REG_B_DM) ? "binary" : "bcd");
+
+        reg = ops->readb(M48T86_REG_D);
+
+        seq_printf(seq, "battery\t\t: %s\n",
+                 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
+
+        return 0;
+}
+
+static struct rtc_class_ops m48t86_rtc_ops = {
+        .read_time      = m48t86_rtc_read_time,
+        .set_time       = m48t86_rtc_set_time,
+        .proc           = m48t86_rtc_proc,
+};
+
+static int __devinit m48t86_rtc_probe(struct platform_device *dev)
+{
+        unsigned char reg;
+        struct m48t86_ops *ops = dev->dev.platform_data;
+        struct rtc_device *rtc = rtc_device_register("m48t86",
+                                &dev->dev, &m48t86_rtc_ops, THIS_MODULE);
+
+        if (IS_ERR(rtc)) {
+                dev_err(&dev->dev, "unable to register\n");
+                return PTR_ERR(rtc);
+        }
+
+        platform_set_drvdata(dev, rtc);
+
+        /* read battery status */
+        reg = ops->readb(M48T86_REG_D);
+        dev_info(&dev->dev, "battery %s\n",
+                (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
+
+        return 0;
+}
+
+static int __devexit m48t86_rtc_remove(struct platform_device *dev)
+{
+        struct rtc_device *rtc = platform_get_drvdata(dev);
+
+        if (rtc)
+                rtc_device_unregister(rtc);
+
+        platform_set_drvdata(dev, NULL);
+
+        return 0;
+}
+
+static struct platform_driver m48t86_rtc_platform_driver = {
+        .driver         = {
+                .name   = "rtc-m48t86",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = m48t86_rtc_probe,
+        .remove         = __devexit_p(m48t86_rtc_remove),
+};
+
+static int __init m48t86_rtc_init(void)
+{
+        return platform_driver_register(&m48t86_rtc_platform_driver);
+}
+
+static void __exit m48t86_rtc_exit(void)
+{
+        platform_driver_unregister(&m48t86_rtc_platform_driver);
+}
+
+MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("M48T86 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(m48t86_rtc_init);
+module_exit(m48t86_rtc_exit);
diff --git a/include/linux/m48t86.h b/include/linux/m48t86.h
new file mode 100644
index 000000000000..9065199319d0
--- /dev/null
+++ b/include/linux/m48t86.h
@@ -0,0 +1,16 @@
+/*
+ * ST M48T86 / Dallas DS12887 RTC driver
+ * Copyright (c) 2006 Tower Technologies
+ *
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * 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.
+*/
+
+struct m48t86_ops
+{
+        void (*writeb)(unsigned char value, unsigned long addr);
+        unsigned char (*readb)(unsigned long addr);
+};