RTC: M48T35: new RTC driver

This driver replaces the broken ip27-rtc driver in drivers/char and
gives back RTC support for SGI IP27 machines.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Alessandro Zummo <alessandro.zummo@towertech.it>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 244 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 24217008aa35..f3d7fd3406a6 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -410,6 +410,15 @@ config RTC_DRV_M48T86
           This driver can also be built as a module. If so, the module
           will be called rtc-m48t86.
 
+config RTC_DRV_M48T35
+        tristate "ST M48T35"
+        help
+          If you say Y here you will get support for the
+          ST M48T35 RTC chip.
+
+          This driver can also be built as a module, if so, the module
+          will be called "rtc-m48t35".
+
 config RTC_DRV_M48T59
         tristate "ST M48T59/M48T08/M48T02"
         help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index a3208082565c..37a71b727262 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_ISL1208)   += rtc-isl1208.o
 obj-$(CONFIG_RTC_DRV_M41T80)    += rtc-m41t80.o
 obj-$(CONFIG_RTC_DRV_M41T94)    += rtc-m41t94.o
+obj-$(CONFIG_RTC_DRV_M48T35)    += rtc-m48t35.o
 obj-$(CONFIG_RTC_DRV_M48T59)    += rtc-m48t59.o
 obj-$(CONFIG_RTC_DRV_M48T86)    += rtc-m48t86.o
 obj-$(CONFIG_RTC_DRV_BQ4802)    += rtc-bq4802.o
diff --git a/drivers/rtc/rtc-m48t35.c b/drivers/rtc/rtc-m48t35.c
new file mode 100644
index 000000000000..b9c1fe4a198e
--- /dev/null
+++ b/drivers/rtc/rtc-m48t35.c
@@ -0,0 +1,234 @@
+/*
+ * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
+ *
+ * Copyright (C) 2000 Silicon Graphics, Inc.
+ * Written by Ulf Carlsson (ulfc@engr.sgi.com)
+ *
+ * Copyright (C) 2008 Thomas Bogendoerfer
+ *
+ * Based on code written by Paul Gortmaker.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+#include <linux/bcd.h>
+
+#define DRV_VERSION             "1.0"
+
+struct m48t35_rtc {
+        u8      pad[0x7ff8];    /* starts at 0x7ff8 */
+        u8      control;
+        u8      sec;
+        u8      min;
+        u8      hour;
+        u8      day;
+        u8      date;
+        u8      month;
+        u8      year;
+};
+
+#define M48T35_RTC_SET          0x80
+#define M48T35_RTC_READ         0x40
+
+struct m48t35_priv {
+        struct rtc_device *rtc;
+        struct m48t35_rtc __iomem *reg;
+        size_t size;
+        unsigned long baseaddr;
+        spinlock_t lock;
+};
+
+static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct m48t35_priv *priv = dev_get_drvdata(dev);
+        u8 control;
+
+        /*
+         * Only the values that we read from the RTC are set. We leave
+         * tm_wday, tm_yday and tm_isdst untouched. Even though the
+         * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
+         * by the RTC when initially set to a non-zero value.
+         */
+        spin_lock_irq(&priv->lock);
+        control = readb(&priv->reg->control);
+        writeb(control | M48T35_RTC_READ, &priv->reg->control);
+        tm->tm_sec = readb(&priv->reg->sec);
+        tm->tm_min = readb(&priv->reg->min);
+        tm->tm_hour = readb(&priv->reg->hour);
+        tm->tm_mday = readb(&priv->reg->date);
+        tm->tm_mon = readb(&priv->reg->month);
+        tm->tm_year = readb(&priv->reg->year);
+        writeb(control, &priv->reg->control);
+        spin_unlock_irq(&priv->lock);
+
+        tm->tm_sec = bcd2bin(tm->tm_sec);
+        tm->tm_min = bcd2bin(tm->tm_min);
+        tm->tm_hour = bcd2bin(tm->tm_hour);
+        tm->tm_mday = bcd2bin(tm->tm_mday);
+        tm->tm_mon = bcd2bin(tm->tm_mon);
+        tm->tm_year = bcd2bin(tm->tm_year);
+
+        /*
+         * Account for differences between how the RTC uses the values
+         * and how they are defined in a struct rtc_time;
+         */
+        tm->tm_year += 70;
+        if (tm->tm_year <= 69)
+                tm->tm_year += 100;
+
+        tm->tm_mon--;
+        return rtc_valid_tm(tm);
+}
+
+static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct m48t35_priv *priv = dev_get_drvdata(dev);
+        unsigned char mon, day, hrs, min, sec;
+        unsigned int yrs;
+        u8 control;
+
+        yrs = tm->tm_year + 1900;
+        mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
+        day = tm->tm_mday;
+        hrs = tm->tm_hour;
+        min = tm->tm_min;
+        sec = tm->tm_sec;
+
+        if (yrs < 1970)
+                return -EINVAL;
+
+        yrs -= 1970;
+        if (yrs > 255)    /* They are unsigned */
+                return -EINVAL;
+
+        if (yrs > 169)
+                return -EINVAL;
+
+        if (yrs >= 100)
+                yrs -= 100;
+
+        sec = bin2bcd(sec);
+        min = bin2bcd(min);
+        hrs = bin2bcd(hrs);
+        day = bin2bcd(day);
+        mon = bin2bcd(mon);
+        yrs = bin2bcd(yrs);
+
+        spin_lock_irq(&priv->lock);
+        control = readb(&priv->reg->control);
+        writeb(control | M48T35_RTC_SET, &priv->reg->control);
+        writeb(yrs, &priv->reg->year);
+        writeb(mon, &priv->reg->month);
+        writeb(day, &priv->reg->date);
+        writeb(hrs, &priv->reg->hour);
+        writeb(min, &priv->reg->min);
+        writeb(sec, &priv->reg->sec);
+        writeb(control, &priv->reg->control);
+        spin_unlock_irq(&priv->lock);
+        return 0;
+}
+
+static const struct rtc_class_ops m48t35_ops = {
+        .read_time      = m48t35_read_time,
+        .set_time       = m48t35_set_time,
+};
+
+static int __devinit m48t35_probe(struct platform_device *pdev)
+{
+        struct rtc_device *rtc;
+        struct resource *res;
+        struct m48t35_priv *priv;
+        int ret = 0;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!res)
+                return -ENODEV;
+        priv = kzalloc(sizeof(struct m48t35_priv), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        priv->size = res->end - res->start + 1;
+        /*
+         * kludge: remove the #ifndef after ioc3 resource
+         * conflicts are resolved
+         */
+#ifndef CONFIG_SGI_IP27
+        if (!request_mem_region(res->start, priv->size, pdev->name)) {
+                ret = -EBUSY;
+                goto out;
+        }
+#endif
+        priv->baseaddr = res->start;
+        priv->reg = ioremap(priv->baseaddr, priv->size);
+        if (!priv->reg) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        spin_lock_init(&priv->lock);
+        rtc = rtc_device_register("m48t35", &pdev->dev,
+                                  &m48t35_ops, THIS_MODULE);
+        if (IS_ERR(rtc)) {
+                ret = PTR_ERR(rtc);
+                goto out;
+        }
+        priv->rtc = rtc;
+        platform_set_drvdata(pdev, priv);
+        return 0;
+
+out:
+        if (priv->rtc)
+                rtc_device_unregister(priv->rtc);
+        if (priv->reg)
+                iounmap(priv->reg);
+        if (priv->baseaddr)
+                release_mem_region(priv->baseaddr, priv->size);
+        kfree(priv);
+        return ret;
+}
+
+static int __devexit m48t35_remove(struct platform_device *pdev)
+{
+        struct m48t35_priv *priv = platform_get_drvdata(pdev);
+
+        rtc_device_unregister(priv->rtc);
+        iounmap(priv->reg);
+#ifndef CONFIG_SGI_IP27
+        release_mem_region(priv->baseaddr, priv->size);
+#endif
+        kfree(priv);
+        return 0;
+}
+
+static struct platform_driver m48t35_platform_driver = {
+        .driver         = {
+                .name   = "rtc-m48t35",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = m48t35_probe,
+        .remove         = __devexit_p(m48t35_remove),
+};
+
+static int __init m48t35_init(void)
+{
+        return platform_driver_register(&m48t35_platform_driver);
+}
+
+static void __exit m48t35_exit(void)
+{
+        platform_driver_unregister(&m48t35_platform_driver);
+}
+
+MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
+MODULE_DESCRIPTION("M48T35 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+MODULE_ALIAS("platform:rtc-m48t35");
+
+module_init(m48t35_init);
+module_exit(m48t35_exit);