rtc: add platform driver for EFI

Munge Stephane Eranian's efirtc.c code into an rtc platform driver

[akpm@linux-foundation.org: use is_leap_year()]
Signed-off-by: dann frazier <dannf@hp.com>
Cc: Alessandro Zummo <alessandro.zummo@towertech.it>
Cc: stephane eranian <eranian@googlemail.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
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>

3 files changed, 246 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 81450fbd8b12..d669b9169278 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -440,6 +440,16 @@ config RTC_DRV_DS1742
           This driver can also be built as a module. If so, the module
           will be called rtc-ds1742.
 
+config RTC_DRV_EFI
+        tristate "EFI RTC"
+        depends on IA64
+        help
+          If you say yes here you will get support for the EFI
+          Real Time Clock.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-efi.
+
 config RTC_DRV_STK17TA8
         tristate "Simtek STK17TA8"
         depends on RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 0e697aa51caa..e7b09986d26e 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o
 obj-$(CONFIG_RTC_DRV_DS1672)    += rtc-ds1672.o
 obj-$(CONFIG_RTC_DRV_DS1742)    += rtc-ds1742.o
 obj-$(CONFIG_RTC_DRV_DS3234)    += rtc-ds3234.o
+obj-$(CONFIG_RTC_DRV_EFI)       += rtc-efi.o
 obj-$(CONFIG_RTC_DRV_EP93XX)    += rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_FM3130)    += rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_ISL1208)   += rtc-isl1208.o
diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
new file mode 100644
index 000000000000..550292304b0f
--- /dev/null
+++ b/drivers/rtc/rtc-efi.c
@@ -0,0 +1,235 @@
+/*
+ * rtc-efi: RTC Class Driver for EFI-based systems
+ *
+ * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
+ *
+ * Author: dann frazier <dannf@hp.com>
+ * Based on efirtc.c by Stephane Eranian
+ *
+ *  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/kernel.h>
+#include <linux/module.h>
+#include <linux/time.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/efi.h>
+
+#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
+/*
+ * EFI Epoch is 1/1/1998
+ */
+#define EFI_RTC_EPOCH           1998
+
+/*
+ * returns day of the year [0-365]
+ */
+static inline int
+compute_yday(efi_time_t *eft)
+{
+        /* efi_time_t.month is in the [1-12] so, we need -1 */
+        return rtc_year_days(eft->day - 1, eft->month - 1, eft->year);
+}
+/*
+ * returns day of the week [0-6] 0=Sunday
+ *
+ * Don't try to provide a year that's before 1998, please !
+ */
+static int
+compute_wday(efi_time_t *eft)
+{
+        int y;
+        int ndays = 0;
+
+        if (eft->year < 1998) {
+                printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
+                return -1;
+        }
+
+        for (y = EFI_RTC_EPOCH; y < eft->year; y++)
+                ndays += 365 + (is_leap_year(y) ? 1 : 0);
+
+        ndays += compute_yday(eft);
+
+        /*
+         * 4=1/1/1998 was a Thursday
+         */
+        return (ndays + 4) % 7;
+}
+
+static void
+convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
+{
+        eft->year       = wtime->tm_year + 1900;
+        eft->month      = wtime->tm_mon + 1;
+        eft->day        = wtime->tm_mday;
+        eft->hour       = wtime->tm_hour;
+        eft->minute     = wtime->tm_min;
+        eft->second     = wtime->tm_sec;
+        eft->nanosecond = 0;
+        eft->daylight   = wtime->tm_isdst ? EFI_ISDST : 0;
+        eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
+}
+
+static void
+convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
+{
+        memset(wtime, 0, sizeof(*wtime));
+        wtime->tm_sec  = eft->second;
+        wtime->tm_min  = eft->minute;
+        wtime->tm_hour = eft->hour;
+        wtime->tm_mday = eft->day;
+        wtime->tm_mon  = eft->month - 1;
+        wtime->tm_year = eft->year - 1900;
+
+        /* day of the week [0-6], Sunday=0 */
+        wtime->tm_wday = compute_wday(eft);
+
+        /* day in the year [1-365]*/
+        wtime->tm_yday = compute_yday(eft);
+
+
+        switch (eft->daylight & EFI_ISDST) {
+        case EFI_ISDST:
+                wtime->tm_isdst = 1;
+                break;
+        case EFI_TIME_ADJUST_DAYLIGHT:
+                wtime->tm_isdst = 0;
+                break;
+        default:
+                wtime->tm_isdst = -1;
+        }
+}
+
+static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+        efi_time_t eft;
+        efi_status_t status;
+
+        /*
+         * As of EFI v1.10, this call always returns an unsupported status
+         */
+        status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
+                                     (efi_bool_t *)&wkalrm->pending, &eft);
+
+        if (status != EFI_SUCCESS)
+                return -EINVAL;
+
+        convert_from_efi_time(&eft, &wkalrm->time);
+
+        return rtc_valid_tm(&wkalrm->time);
+}
+
+static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+        efi_time_t eft;
+        efi_status_t status;
+
+        convert_to_efi_time(&wkalrm->time, &eft);
+
+        /*
+         * XXX Fixme:
+         * As of EFI 0.92 with the firmware I have on my
+         * machine this call does not seem to work quite
+         * right
+         *
+         * As of v1.10, this call always returns an unsupported status
+         */
+        status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
+
+        printk(KERN_WARNING "write status is %d\n", (int)status);
+
+        return status == EFI_SUCCESS ? 0 : -EINVAL;
+}
+
+static int efi_read_time(struct device *dev, struct rtc_time *tm)
+{
+        efi_status_t status;
+        efi_time_t eft;
+        efi_time_cap_t cap;
+
+        status = efi.get_time(&eft, &cap);
+
+        if (status != EFI_SUCCESS) {
+                /* should never happen */
+                printk(KERN_ERR "efitime: can't read time\n");
+                return -EINVAL;
+        }
+
+        convert_from_efi_time(&eft, tm);
+
+        return rtc_valid_tm(tm);
+}
+
+static int efi_set_time(struct device *dev, struct rtc_time *tm)
+{
+        efi_status_t status;
+        efi_time_t eft;
+
+        convert_to_efi_time(tm, &eft);
+
+        status = efi.set_time(&eft);
+
+        return status == EFI_SUCCESS ? 0 : -EINVAL;
+}
+
+static const struct rtc_class_ops efi_rtc_ops = {
+        .read_time = efi_read_time,
+        .set_time = efi_set_time,
+        .read_alarm = efi_read_alarm,
+        .set_alarm = efi_set_alarm,
+};
+
+static int __init efi_rtc_probe(struct platform_device *dev)
+{
+        struct rtc_device *rtc;
+
+        rtc = rtc_device_register("rtc-efi", &dev->dev, &efi_rtc_ops,
+                                        THIS_MODULE);
+        if (IS_ERR(rtc))
+                return PTR_ERR(rtc);
+
+        platform_set_drvdata(dev, rtc);
+
+        return 0;
+}
+
+static int __exit efi_rtc_remove(struct platform_device *dev)
+{
+        struct rtc_device *rtc = platform_get_drvdata(dev);
+
+        rtc_device_unregister(rtc);
+
+        return 0;
+}
+
+static struct platform_driver efi_rtc_driver = {
+        .driver = {
+                .name = "rtc-efi",
+                .owner = THIS_MODULE,
+        },
+        .probe = efi_rtc_probe,
+        .remove = __exit_p(efi_rtc_remove),
+};
+
+static int __init efi_rtc_init(void)
+{
+        return platform_driver_probe(&efi_rtc_driver, efi_rtc_probe);
+}
+
+static void __exit efi_rtc_exit(void)
+{
+        platform_driver_unregister(&efi_rtc_driver);
+}
+
+module_init(efi_rtc_init);
+module_exit(efi_rtc_exit);
+
+MODULE_AUTHOR("dann frazier <dannf@hp.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("EFI RTC driver");