alarmtimer: Make alarmtimer platform device child of RTC device

The alarmtimer_suspend() function will fail if an RTC device is on a bus
such as SPI or i2c and that RTC device registers and probes after
alarmtimer_init() registers and probes the 'alarmtimer' platform device.

This is because system wide suspend suspends devices in the reverse order
of their probe. When alarmtimer_suspend() attempts to program the RTC for a
wakeup it will try to program an RTC device on a bus that has already been
suspended.

Move the alarmtimer device registration to happen when the RTC which is
used for wakeup is registered. Register the 'alarmtimer' platform device as
a child of the RTC device too, so that it can be guaranteed that the RTC
device won't be suspended when alarmtimer_suspend() is called.

Reported-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200124055849.154411-2-swboyd@chromium.org

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 564ff5d..f0469cc 100644 (file)
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -89,6 +89,7 @@ static int alarmtimer_rtc_add_device(struct device *dev,
        unsigned long flags;
        struct rtc_device *rtc = to_rtc_device(dev);
        struct wakeup_source *__ws;
+       struct platform_device *pdev;
        int ret = 0;
 
        if (rtcdev)
@@ -100,9 +101,11 @@ static int alarmtimer_rtc_add_device(struct device *dev,
                return -1;
 
        __ws = wakeup_source_register(dev, "alarmtimer");
+       pdev = platform_device_register_data(dev, "alarmtimer",
+                                            PLATFORM_DEVID_AUTO, NULL, 0);
 
        spin_lock_irqsave(&rtcdev_lock, flags);
-       if (!rtcdev) {
+       if (__ws && !IS_ERR(pdev) && !rtcdev) {
                if (!try_module_get(rtc->owner)) {
                        ret = -1;
                        goto unlock;
@@ -113,10 +116,14 @@ static int alarmtimer_rtc_add_device(struct device *dev,
                get_device(dev);
                ws = __ws;
                __ws = NULL;
+               pdev = NULL;
+       } else {
+               ret = -1;
        }
 unlock:
        spin_unlock_irqrestore(&rtcdev_lock, flags);
 
+       platform_device_unregister(pdev);
        wakeup_source_unregister(__ws);
 
        return ret;
@@ -903,8 +910,7 @@ static void get_boottime_timespec(struct timespec64 *tp)
  */
 static int __init alarmtimer_init(void)
 {
-       struct platform_device *pdev;
-       int error = 0;
+       int error;
        int i;
 
        alarmtimer_rtc_timer_init();
@@ -929,15 +935,7 @@ static int __init alarmtimer_init(void)
        if (error)
                goto out_if;
 
-       pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
-       if (IS_ERR(pdev)) {
-               error = PTR_ERR(pdev);
-               goto out_drv;
-       }
        return 0;
-
-out_drv:
-       platform_driver_unregister(&alarmtimer_driver);
 out_if:
        alarmtimer_rtc_interface_remove();
        return error;