Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=7ca1d488ffe4817adaba61cc05b972782f7d3f91
Commit:     7ca1d488ffe4817adaba61cc05b972782f7d3f91
Parent:     cd9662094edf4173e87f0452e57e4eacc228f8ff
Author:     David Brownell <[EMAIL PROTECTED]>
AuthorDate: Tue May 8 00:33:42 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue May 8 11:15:18 2007 -0700

    rtc: suspend()/resume() restores system clock
    
    RTC class suspend/resume support, re-initializing the system clock on resume
    from the clock used to initialize it at boot time.
    
     - The reinit-on-resume is hooked to the existing RTC_HCTOSYS config
       option, on the grounds that a clock good enough for init must also
       be good enough for re-init.
    
     - Inlining a version of the code used by ARM, to save and restore the
       delta between a selected RTC and the current system wall-clock time.
    
     - Removes calls to that ARM code from AT91, OMAP1, and S3C RTCs.  This
       means that systems using those RTCs across suspend/resume will likely
       want to change their kernel configs to enable RTC_HCTOSYS.
    
       If HCTOSYS isn't using a second RTC (with battery?), this changes the
       system's initial date from Jan 1970 to the epoch this hardware uses:
       1998 for AT91, 2000 for OMAP1 (assuming no split power mode), etc.
    
    This goes on top of the patch series removing "struct class_device" usage
    from the RTC framework.  That's all needed for class suspend()/resume().
    
    Signed-off-by: David Brownell <[EMAIL PROTECTED]>
    Acked-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
    Acked-By: Alessandro Zummo <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 drivers/rtc/Kconfig          |   24 +++++++++----
 drivers/rtc/class.c          |   74 ++++++++++++++++++++++++++++++++++++++++++
 drivers/rtc/rtc-at91rm9200.c |   30 -----------------
 drivers/rtc/rtc-omap.c       |   17 ---------
 drivers/rtc/rtc-s3c.c        |   22 ------------
 5 files changed, 91 insertions(+), 76 deletions(-)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index ec33ee8..a53ef4d 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -21,21 +21,31 @@ config RTC_CLASS
          will be called rtc-class.
 
 config RTC_HCTOSYS
-       bool "Set system time from RTC on startup"
+       bool "Set system time from RTC on startup and resume"
        depends on RTC_CLASS = y
        default y
        help
-         If you say yes here, the system time will be set using
-         the value read from the specified RTC device. This is useful
-         in order to avoid unnecessary fsck runs.
+         If you say yes here, the system time (wall clock) will be set using
+         the value read from a specified RTC device. This is useful to avoid
+         unnecessary fsck runs at boot time, and to network better.
 
 config RTC_HCTOSYS_DEVICE
-       string "The RTC to read the time from"
+       string "RTC used to set the system time"
        depends on RTC_HCTOSYS = y
        default "rtc0"
        help
-         The RTC device that will be used as the source for
-         the system time, usually rtc0.
+         The RTC device that will be used to (re)initialize the system
+         clock, usually rtc0.  Initialization is done when the system
+         starts up, and when it resumes from a low power state.
+
+         This clock should be battery-backed, so that it reads the correct
+         time when the system boots from a power-off state.  Otherwise, your
+         system will need an external clock source (like an NTP server).
+
+         If the clock you specify here is not battery backed, it may still
+         be useful to reinitialize system time when resuming from system
+         sleep states.  Do not specify an RTC here unless it stays powered
+         during all this system's supported sleep states.
 
 config RTC_DEBUG
        bool "RTC debug support"
diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index d58d74c..587d251 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -32,6 +32,78 @@ static void rtc_device_release(struct device *dev)
        kfree(rtc);
 }
 
+#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
+
+/*
+ * On suspend(), measure the delta between one RTC and the
+ * system's wall clock; restore it on resume().
+ */
+
+static struct timespec delta;
+static time_t          oldtime;
+
+static int rtc_suspend(struct device *dev, pm_message_t mesg)
+{
+       struct rtc_device       *rtc = to_rtc_device(dev);
+       struct rtc_time         tm;
+
+       if (strncmp(rtc->dev.bus_id,
+                               CONFIG_RTC_HCTOSYS_DEVICE,
+                               BUS_ID_SIZE) != 0)
+               return 0;
+
+       rtc_read_time(rtc, &tm);
+       rtc_tm_to_time(&tm, &oldtime);
+
+       /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */
+       set_normalized_timespec(&delta,
+                               xtime.tv_sec - oldtime,
+                               xtime.tv_nsec - (NSEC_PER_SEC >> 1));
+
+       return 0;
+}
+
+static int rtc_resume(struct device *dev)
+{
+       struct rtc_device       *rtc = to_rtc_device(dev);
+       struct rtc_time         tm;
+       time_t                  newtime;
+       struct timespec         time;
+
+       if (strncmp(rtc->dev.bus_id,
+                               CONFIG_RTC_HCTOSYS_DEVICE,
+                               BUS_ID_SIZE) != 0)
+               return 0;
+
+       rtc_read_time(rtc, &tm);
+       if (rtc_valid_tm(&tm) != 0) {
+               pr_debug("%s:  bogus resume time\n", rtc->dev.bus_id);
+               return 0;
+       }
+       rtc_tm_to_time(&tm, &newtime);
+       if (newtime <= oldtime) {
+               if (newtime < oldtime)
+                       pr_debug("%s:  time travel!\n", rtc->dev.bus_id);
+               return 0;
+       }
+
+       /* restore wall clock using delta against this RTC;
+        * adjust again for avg 1/2 second RTC sampling error
+        */
+       set_normalized_timespec(&time,
+                               newtime + delta.tv_sec,
+                               (NSEC_PER_SEC >> 1) + delta.tv_nsec);
+       do_settimeofday(&time);
+
+       return 0;
+}
+
+#else
+#define rtc_suspend    NULL
+#define rtc_resume     NULL
+#endif
+
+
 /**
  * rtc_device_register - register w/ RTC class
  * @dev: the device to register
@@ -143,6 +215,8 @@ static int __init rtc_init(void)
                printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
                return PTR_ERR(rtc_class);
        }
+       rtc_class->suspend = rtc_suspend;
+       rtc_class->resume = rtc_resume;
        rtc_dev_init();
        rtc_sysfs_init(rtc_class);
        return 0;
diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
index 2f06b5f..33795e5 100644
--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -348,21 +348,10 @@ static int __exit at91_rtc_remove(struct platform_device 
*pdev)
 
 /* AT91RM9200 RTC Power management control */
 
-static struct timespec at91_rtc_delta;
 static u32 at91_rtc_imr;
 
 static int at91_rtc_suspend(struct platform_device *pdev, pm_message_t state)
 {
-       struct rtc_time tm;
-       struct timespec time;
-
-       time.tv_nsec = 0;
-
-       /* calculate time delta for suspend */
-       at91_rtc_readtime(&pdev->dev, &tm);
-       rtc_tm_to_time(&tm, &time.tv_sec);
-       save_time_delta(&at91_rtc_delta, &time);
-
        /* this IRQ is shared with DBGU and other hardware which isn't
         * necessarily doing PM like we are...
         */
@@ -374,36 +363,17 @@ static int at91_rtc_suspend(struct platform_device *pdev, 
pm_message_t state)
                else
                        at91_sys_write(AT91_RTC_IDR, at91_rtc_imr);
        }
-
-       pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
-               1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
-               tm.tm_hour, tm.tm_min, tm.tm_sec);
-
        return 0;
 }
 
 static int at91_rtc_resume(struct platform_device *pdev)
 {
-       struct rtc_time tm;
-       struct timespec time;
-
-       time.tv_nsec = 0;
-
-       at91_rtc_readtime(&pdev->dev, &tm);
-       rtc_tm_to_time(&tm, &time.tv_sec);
-       restore_time_delta(&at91_rtc_delta, &time);
-
        if (at91_rtc_imr) {
                if (device_may_wakeup(&pdev->dev))
                        disable_irq_wake(AT91_ID_SYS);
                else
                        at91_sys_write(AT91_RTC_IER, at91_rtc_imr);
        }
-
-       pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
-               1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
-               tm.tm_hour, tm.tm_min, tm.tm_sec);
-
        return 0;
 }
 #else
diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index ded35fd..e6c7b01 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -488,19 +488,10 @@ static int __devexit omap_rtc_remove(struct 
platform_device *pdev)
 
 #ifdef CONFIG_PM
 
-static struct timespec rtc_delta;
 static u8 irqstat;
 
 static int omap_rtc_suspend(struct platform_device *pdev, pm_message_t state)
 {
-       struct rtc_time rtc_tm;
-       struct timespec time;
-
-       time.tv_nsec = 0;
-       omap_rtc_read_time(NULL, &rtc_tm);
-       rtc_tm_to_time(&rtc_tm, &time.tv_sec);
-
-       save_time_delta(&rtc_delta, &time);
        irqstat = rtc_read(OMAP_RTC_INTERRUPTS_REG);
 
        /* FIXME the RTC alarm is not currently acting as a wakeup event
@@ -517,14 +508,6 @@ static int omap_rtc_suspend(struct platform_device *pdev, 
pm_message_t state)
 
 static int omap_rtc_resume(struct platform_device *pdev)
 {
-       struct rtc_time rtc_tm;
-       struct timespec time;
-
-       time.tv_nsec = 0;
-       omap_rtc_read_time(NULL, &rtc_tm);
-       rtc_tm_to_time(&rtc_tm, &time.tv_sec);
-
-       restore_time_delta(&rtc_delta, &time);
        if (device_may_wakeup(&pdev->dev))
                disable_irq_wake(omap_rtc_alarm);
        else
diff --git a/drivers/rtc/rtc-s3c.c b/drivers/rtc/rtc-s3c.c
index 3617c97..54b6130 100644
--- a/drivers/rtc/rtc-s3c.c
+++ b/drivers/rtc/rtc-s3c.c
@@ -548,37 +548,15 @@ static int ticnt_save;
 
 static int s3c_rtc_suspend(struct platform_device *pdev, pm_message_t state)
 {
-       struct rtc_time tm;
-       struct timespec time;
-
-       time.tv_nsec = 0;
-
        /* save TICNT for anyone using periodic interrupts */
-
        ticnt_save = readb(s3c_rtc_base + S3C2410_TICNT);
-
-       /* calculate time delta for suspend */
-
-       s3c_rtc_gettime(&pdev->dev, &tm);
-       rtc_tm_to_time(&tm, &time.tv_sec);
-       save_time_delta(&s3c_rtc_delta, &time);
        s3c_rtc_enable(pdev, 0);
-
        return 0;
 }
 
 static int s3c_rtc_resume(struct platform_device *pdev)
 {
-       struct rtc_time tm;
-       struct timespec time;
-
-       time.tv_nsec = 0;
-
        s3c_rtc_enable(pdev, 1);
-       s3c_rtc_gettime(&pdev->dev, &tm);
-       rtc_tm_to_time(&tm, &time.tv_sec);
-       restore_time_delta(&s3c_rtc_delta, &time);
-
        writeb(ticnt_save, s3c_rtc_base + S3C2410_TICNT);
        return 0;
 }
-
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