RTC driver for DS1216 chips

RTC driver for Dallas/Maxim DS126 chips used in SNI RM200/RM400

[akpm@linux-foundation.org: cleanups]
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/Kconfig

@@ -280,6 +280,12 @@ config RTC_DRV_CMOS
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-cmos.
 
+config RTC_DRV_DS1216
+	tristate "Dallas DS1216"
+	depends on RTC_CLASS && SNI_RM
+	help
+	  If you say yes here you get support for the Dallas DS1216 RTC chips.
+
 config RTC_DRV_DS1553
 	tristate "Dallas DS1553"
 	depends on RTC_CLASS

drivers/rtc/Makefile

@@ -44,3 +44,4 @@ obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
 obj-$(CONFIG_RTC_DRV_SH)	+= rtc-sh.o
 obj-$(CONFIG_RTC_DRV_BFIN)	+= rtc-bfin.o
 obj-$(CONFIG_RTC_DRV_M48T59)	+= rtc-m48t59.o
+obj-$(CONFIG_RTC_DRV_DS1216)	+= rtc-ds1216.o

drivers/rtc/rtc-ds1216.c

+/*
+ * Dallas DS1216 RTC driver
+ *
+ * Copyright (c) 2007 Thomas Bogendoerfer
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+#include <linux/bcd.h>
+
+#define DRV_VERSION "0.1"
+
+struct ds1216_regs {
+	u8 tsec;
+	u8 sec;
+	u8 min;
+	u8 hour;
+	u8 wday;
+	u8 mday;
+	u8 month;
+	u8 year;
+};
+
+#define DS1216_HOUR_1224	(1 << 7)
+#define DS1216_HOUR_AMPM	(1 << 5)
+
+struct ds1216_priv {
+	struct rtc_device *rtc;
+	void __iomem *ioaddr;
+	size_t size;
+	unsigned long baseaddr;
+};
+
+static const u8 magic[] = {
+	0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
+};
+
+/*
+ * Read the 64 bit we'd like to have - It a series
+ * of 64 bits showing up in the LSB of the base register.
+ *
+ */
+static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
+{
+	unsigned char c;
+	int i, j;
+
+	for (i = 0; i < 8; i++) {
+		c = 0;
+		for (j = 0; j < 8; j++)
+			c |= (readb(ioaddr) & 0x1) << j;
+		buf[i] = c;
+	}
+}
+
+static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
+{
+	unsigned char c;
+	int i, j;
+
+	for (i = 0; i < 8; i++) {
+		c = buf[i];
+		for (j = 0; j < 8; j++) {
+			writeb(c, ioaddr);
+			c = c >> 1;
+		}
+	}
+}
+
+static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
+{
+	/* Reset magic pointer */
+	readb(ioaddr);
+	/* Write 64 bit magic to DS1216 */
+	ds1216_write(ioaddr, magic);
+}
+
+static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct ds1216_priv *priv = platform_get_drvdata(pdev);
+	struct ds1216_regs regs;
+
+	ds1216_switch_ds_to_clock(priv->ioaddr);
+	ds1216_read(priv->ioaddr, (u8 *)&regs);
+
+	tm->tm_sec = BCD2BIN(regs.sec);
+	tm->tm_min = BCD2BIN(regs.min);
+	if (regs.hour & DS1216_HOUR_1224) {
+		/* AM/PM mode */
+		tm->tm_hour = BCD2BIN(regs.hour & 0x1f);
+		if (regs.hour & DS1216_HOUR_AMPM)
+			tm->tm_hour += 12;
+	} else
+		tm->tm_hour = BCD2BIN(regs.hour & 0x3f);
+	tm->tm_wday = (regs.wday & 7) - 1;
+	tm->tm_mday = BCD2BIN(regs.mday & 0x3f);
+	tm->tm_mon = BCD2BIN(regs.month & 0x1f);
+	tm->tm_year = BCD2BIN(regs.year);
+	if (tm->tm_year < 70)
+		tm->tm_year += 100;
+	return 0;
+}
+
+static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct ds1216_priv *priv = platform_get_drvdata(pdev);
+	struct ds1216_regs regs;
+
+	ds1216_switch_ds_to_clock(priv->ioaddr);
+	ds1216_read(priv->ioaddr, (u8 *)&regs);
+
+	regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
+	regs.sec = BIN2BCD(tm->tm_sec);
+	regs.min = BIN2BCD(tm->tm_min);
+	regs.hour &= DS1216_HOUR_1224;
+	if (regs.hour && tm->tm_hour > 12) {
+		regs.hour |= DS1216_HOUR_AMPM;
+		tm->tm_hour -= 12;
+	}
+	regs.hour |= BIN2BCD(tm->tm_hour);
+	regs.wday &= ~7;
+	regs.wday |= tm->tm_wday;
+	regs.mday = BIN2BCD(tm->tm_mday);
+	regs.month = BIN2BCD(tm->tm_mon);
+	regs.year = BIN2BCD(tm->tm_year % 100);
+
+	ds1216_switch_ds_to_clock(priv->ioaddr);
+	ds1216_write(priv->ioaddr, (u8 *)&regs);
+	return 0;
+}
+
+static const struct rtc_class_ops ds1216_rtc_ops = {
+	.read_time	= ds1216_rtc_read_time,
+	.set_time	= ds1216_rtc_set_time,
+};
+
+static int __devinit ds1216_rtc_probe(struct platform_device *pdev)
+{
+	struct rtc_device *rtc;
+	struct resource *res;
+	struct ds1216_priv *priv;
+	int ret = 0;
+	u8 dummy[8];
+
+	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;
+	if (!request_mem_region(res->start, priv->size, pdev->name)) {
+		ret = -EBUSY;
+		goto out;
+	}
+	priv->baseaddr = res->start;
+	priv->ioaddr = ioremap(priv->baseaddr, priv->size);
+	if (!priv->ioaddr) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	rtc = rtc_device_register("ds1216", &pdev->dev,
+				  &ds1216_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		ret = PTR_ERR(rtc);
+		goto out;
+	}
+	priv->rtc = rtc;
+	platform_set_drvdata(pdev, priv);
+
+	/* dummy read to get clock into a known state */
+	ds1216_read(priv->ioaddr, dummy);
+	return 0;
+
+out:
+	if (priv->rtc)
+		rtc_device_unregister(priv->rtc);
+	if (priv->ioaddr)
+		iounmap(priv->ioaddr);
+	if (priv->baseaddr)
+		release_mem_region(priv->baseaddr, priv->size);
+	kfree(priv);
+	return ret;
+}
+
+static int __devexit ds1216_rtc_remove(struct platform_device *pdev)
+{
+	struct ds1216_priv *priv = platform_get_drvdata(pdev);
+
+	rtc_device_unregister(priv->rtc);
+	iounmap(priv->ioaddr);
+	release_mem_region(priv->baseaddr, priv->size);
+	kfree(priv);
+	return 0;
+}
+
+static struct platform_driver ds1216_rtc_platform_driver = {
+	.driver		= {
+		.name	= "rtc-ds1216",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= ds1216_rtc_probe,
+	.remove		= __devexit_p(ds1216_rtc_remove),
+};
+
+static int __init ds1216_rtc_init(void)
+{
+	return platform_driver_register(&ds1216_rtc_platform_driver);
+}
+
+static void __exit ds1216_rtc_exit(void)
+{
+	platform_driver_unregister(&ds1216_rtc_platform_driver);
+}
+
+MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
+MODULE_DESCRIPTION("DS1216 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(ds1216_rtc_init);
+module_exit(ds1216_rtc_exit);