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path: root/drivers/rtc/rtc-ds1216.c
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Diffstat (limited to 'drivers/rtc/rtc-ds1216.c')
-rw-r--r--drivers/rtc/rtc-ds1216.c182
1 files changed, 182 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1216.c b/drivers/rtc/rtc-ds1216.c
new file mode 100644
index 000000000..d16f55089
--- /dev/null
+++ b/drivers/rtc/rtc-ds1216.c
@@ -0,0 +1,182 @@
+/*
+ * 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>
+#include <linux/slab.h>
+
+#define DRV_VERSION "0.2"
+
+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;
+};
+
+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 rtc_valid_tm(tm);
+}
+
+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 __init ds1216_rtc_probe(struct platform_device *pdev)
+{
+ struct resource *res;
+ struct ds1216_priv *priv;
+ u8 dummy[8];
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, priv);
+
+ priv->ioaddr = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(priv->ioaddr))
+ return PTR_ERR(priv->ioaddr);
+
+ priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216",
+ &ds1216_rtc_ops, THIS_MODULE);
+ if (IS_ERR(priv->rtc))
+ return PTR_ERR(priv->rtc);
+
+ /* dummy read to get clock into a known state */
+ ds1216_read(priv->ioaddr, dummy);
+ return 0;
+}
+
+static struct platform_driver ds1216_rtc_platform_driver = {
+ .driver = {
+ .name = "rtc-ds1216",
+ },
+};
+
+module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
+
+MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
+MODULE_DESCRIPTION("DS1216 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+MODULE_ALIAS("platform:rtc-ds1216");