alarmtimers: Rework RTC device selection using class interface

This allows cleaner detection of the RTC device being registered, rather
then probing any time someone calls alarmtimer_get_rtcdev.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 40 insertions, 38 deletions

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index bdb7342b6896..154d5563ab1b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -53,27 +53,6 @@ static struct rtc_device	*rtcdev;
 static DEFINE_SPINLOCK(rtcdev_lock);
 
 /**
- * has_wakealarm - check rtc device has wakealarm ability
- * @dev: current device
- * @name_ptr: name to be returned
- *
- * This helper function checks to see if the rtc device can wake
- * from suspend.
- */
-static int has_wakealarm(struct device *dev, void *name_ptr)
-{
-        struct rtc_device *candidate = to_rtc_device(dev);
-
-        if (!candidate->ops->set_alarm)
-                return 0;
-        if (!device_may_wakeup(candidate->dev.parent))
-                return 0;
-
-        *(const char **)name_ptr = dev_name(dev);
-        return 1;
-}
-
-/**
  * alarmtimer_get_rtcdev - Return selected rtcdevice
  *
  * This function returns the rtc device to use for wakealarms.
@@ -82,37 +61,58 @@ static int has_wakealarm(struct device *dev, void *name_ptr)
  */
 static struct rtc_device *alarmtimer_get_rtcdev(void)
 {
-        struct device *dev;
-        char *str;
         unsigned long flags;
         struct rtc_device *ret;
 
         spin_lock_irqsave(&rtcdev_lock, flags);
-        if (!rtcdev) {
-                /* Find an rtc device and init the rtc_timer */
-                dev = class_find_device(rtc_class, NULL, &str, has_wakealarm);
-                /* If we have a device then str is valid. See has_wakealarm() */
-                if (dev) {
-                        rtcdev = rtc_class_open(str);
-                        /*
-                         * Drop the reference we got in class_find_device,
-                         * rtc_open takes its own.
-                         */
-                        put_device(dev);
-                        rtc_timer_init(&rtctimer, NULL, NULL);
-                }
-        }
         ret = rtcdev;
         spin_unlock_irqrestore(&rtcdev_lock, flags);
 
         return ret;
 }
+
+
+static int alarmtimer_rtc_add_device(struct device *dev,
+                                struct class_interface *class_intf)
+{
+        unsigned long flags;
+        struct rtc_device *rtc = to_rtc_device(dev);
+
+        if (rtcdev)
+                return -EBUSY;
+
+        if (!rtc->ops->set_alarm)
+                return -1;
+        if (!device_may_wakeup(rtc->dev.parent))
+                return -1;
+
+        spin_lock_irqsave(&rtcdev_lock, flags);
+        if (!rtcdev) {
+                rtcdev = rtc;
+                /* hold a reference so it doesn't go away */
+                get_device(dev);
+        }
+        spin_unlock_irqrestore(&rtcdev_lock, flags);
+        return 0;
+}
+
+static struct class_interface alarmtimer_rtc_interface = {
+        .add_dev = &alarmtimer_rtc_add_device,
+};
+
+static void alarmtimer_rtc_interface_setup(void)
+{
+        alarmtimer_rtc_interface.class = rtc_class;
+        class_interface_register(&alarmtimer_rtc_interface);
+}
 #else
 #define alarmtimer_get_rtcdev() (0)
 #define rtcdev (0)
+#define alarmtimer_rtc_interface_setup()
 #endif
 
 
+
 /**
  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
  * @base: pointer to the base where the timer is being run
@@ -244,7 +244,7 @@ static int alarmtimer_suspend(struct device *dev)
         freezer_delta = ktime_set(0, 0);
         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 
-        rtc = rtcdev;
+        rtc = alarmtimer_get_rtcdev();
         /* If we have no rtcdev, just return */
         if (!rtc)
                 return 0;
@@ -792,6 +792,8 @@ static int __init alarmtimer_init(void)
                                 HRTIMER_MODE_ABS);
                 alarm_bases[i].timer.function = alarmtimer_fired;
         }
+
+        alarmtimer_rtc_interface_setup();
         error = platform_driver_register(&alarmtimer_driver);
         platform_device_register_simple("alarmtimer", -1, NULL, 0);