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[PATCH v2] M48T35: new RTC driver

To: rtc-linux@googlegroups.com, linux-mips@linux-mips.org
Subject: [PATCH v2] M48T35: new RTC driver
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Date: Mon, 4 Aug 2008 19:00:25 +0200 (CEST)
Cc: a.zummo@towertech.it, ralf@linux-mips.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
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>
---

Changes in v2:

- don't depend on SGI_IP27
- use rtc_valid_tm() for tm validation
- resource is now a physical address and is ioremapped now
- added kludge to workaround current ioc3 resource conflict

 drivers/rtc/Kconfig      |    9 ++
 drivers/rtc/Makefile     |    1 +
 drivers/rtc/rtc-m48t35.c |  237 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 247 insertions(+), 0 deletions(-)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 90ab738..2e5a578 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -405,6 +405,15 @@ 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"
        help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 18622ef..7d10cc0 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -36,6 +36,7 @@ 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_MAX6900)  += rtc-max6900.o
diff --git a/drivers/rtc/rtc-m48t35.c b/drivers/rtc/rtc-m48t35.c
new file mode 100644
index 0000000..e618b9a
--- /dev/null
+++ b/drivers/rtc/rtc-m48t35.c
@@ -0,0 +1,237 @@
+/*
+ * 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 (!rtc_valid_tm(tm))
+               return -EINVAL;
+
+       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 *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);

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