linux-kernel - [PATCH 2/4] alarmtimer: Make alarmtimer platform device child of RTC device

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Date:   Thu,  9 Jan 2020 07:59:08 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Douglas Anderson <dianders@...omium.org>,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>,
        linux-kernel@...r.kernel.org, Stephen Boyd <sboyd@...nel.org>
Subject: [PATCH 2/4] 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.

Let's move the alarmtimer device registration to be when the RTC we use
for wakeup is registered. Register the 'alarmtimer' platform device as a
child of the RTC device too, so that we 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>
---
 kernel/time/alarmtimer.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 4b11f0309eee..ccb6aea4f1d4 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -88,6 +88,7 @@ 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)
@@ -99,6 +100,7 @@ static int alarmtimer_rtc_add_device(struct device *dev,
 		return -1;
 
 	__ws = wakeup_source_register(dev, "alarmtimer");
+	pdev = platform_device_register_data(dev, "alarmtimer", -1, NULL, 0);
 
 	spin_lock_irqsave(&rtcdev_lock, flags);
 	if (!rtcdev) {
@@ -112,10 +114,12 @@ static int alarmtimer_rtc_add_device(struct device *dev,
 		get_device(dev);
 		ws = __ws;
 		__ws = NULL;
+		pdev = NULL;
 	}
 unlock:
 	spin_unlock_irqrestore(&rtcdev_lock, flags);
 
+	platform_device_unregister(pdev);
 	wakeup_source_unregister(__ws);
 
 	return ret;
@@ -876,8 +880,7 @@ static struct platform_driver alarmtimer_driver = {
  */
 static int __init alarmtimer_init(void)
 {
-	struct platform_device *pdev;
-	int error = 0;
+	int error;
 	int i;
 
 	alarmtimer_rtc_timer_init();
@@ -900,15 +903,7 @@ 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;
-- 
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