linux-kernel - [tip: timers/core] alarmtimer: Make alarmtimer platform device child of RTC device

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Date:   Fri, 24 Jan 2020 20:08:04 -0000
From:   "tip-bot2 for Stephen Boyd" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Douglas Anderson <dianders@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: timers/core] alarmtimer: Make alarmtimer platform device child
 of RTC device

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     c79108bd19a8490315847e0c95ac6526fcd8e770
Gitweb:        https://git.kernel.org/tip/c79108bd19a8490315847e0c95ac6526fcd8e770
Author:        Stephen Boyd <swboyd@...omium.org>
AuthorDate:    Thu, 23 Jan 2020 21:58:46 -08:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Fri, 24 Jan 2020 21:00:20 +01:00

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

---
 kernel/time/alarmtimer.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 564ff5d..f0469cc 100644
--- 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;