Input: pwm-beeper - fix - scheduling while atomic

Pwm config may sleep so defer it using a worker.

On a Freescale i.MX53 based board we ran into "BUG: scheduling while
atomic" because input_inject_event locks interrupts, but
imx_pwm_config_v2 sleeps.

Tested on Freescale i.MX53 SoC with 4.6.0.

Signed-off-by: Manfred Schlaegl <manfred.schlaegl@gmx.at>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 48 insertions, 21 deletions

diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
index f2261ab54701..18663d4edae5 100644
--- a/drivers/input/misc/pwm-beeper.c
+++ b/drivers/input/misc/pwm-beeper.c
@@ -20,21 +20,40 @@
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 
 struct pwm_beeper {
         struct input_dev *input;
         struct pwm_device *pwm;
+        struct work_struct work;
         unsigned long period;
 };
 
 #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
 
+static void __pwm_beeper_set(struct pwm_beeper *beeper)
+{
+        unsigned long period = beeper->period;
+
+        if (period) {
+                pwm_config(beeper->pwm, period / 2, period);
+                pwm_enable(beeper->pwm);
+        } else
+                pwm_disable(beeper->pwm);
+}
+
+static void pwm_beeper_work(struct work_struct *work)
+{
+        struct pwm_beeper *beeper =
+                container_of(work, struct pwm_beeper, work);
+
+        __pwm_beeper_set(beeper);
+}
+
 static int pwm_beeper_event(struct input_dev *input,
                             unsigned int type, unsigned int code, int value)
 {
-        int ret = 0;
         struct pwm_beeper *beeper = input_get_drvdata(input);
-        unsigned long period;
 
         if (type != EV_SND || value < 0)
                 return -EINVAL;
@@ -49,22 +68,31 @@ static int pwm_beeper_event(struct input_dev *input,
                 return -EINVAL;
         }
 
-        if (value == 0) {
-                pwm_disable(beeper->pwm);
-        } else {
-                period = HZ_TO_NANOSECONDS(value);
-                ret = pwm_config(beeper->pwm, period / 2, period);
-                if (ret)
-                        return ret;
-                ret = pwm_enable(beeper->pwm);
-                if (ret)
-                        return ret;
-                beeper->period = period;
-        }
+        if (value == 0)
+                beeper->period = 0;
+        else
+                beeper->period = HZ_TO_NANOSECONDS(value);
+
+        schedule_work(&beeper->work);
 
         return 0;
 }
 
+static void pwm_beeper_stop(struct pwm_beeper *beeper)
+{
+        cancel_work_sync(&beeper->work);
+
+        if (beeper->period)
+                pwm_disable(beeper->pwm);
+}
+
+static void pwm_beeper_close(struct input_dev *input)
+{
+        struct pwm_beeper *beeper = input_get_drvdata(input);
+
+        pwm_beeper_stop(beeper);
+}
+
 static int pwm_beeper_probe(struct platform_device *pdev)
 {
         unsigned long pwm_id = (unsigned long)dev_get_platdata(&pdev->dev);
@@ -87,6 +115,8 @@ static int pwm_beeper_probe(struct platform_device *pdev)
                 goto err_free;
         }
 
+        INIT_WORK(&beeper->work, pwm_beeper_work);
+
         beeper->input = input_allocate_device();
         if (!beeper->input) {
                 dev_err(&pdev->dev, "Failed to allocate input device\n");
@@ -106,6 +136,7 @@ static int pwm_beeper_probe(struct platform_device *pdev)
         beeper->input->sndbit[0] = BIT(SND_TONE) | BIT(SND_BELL);
 
         beeper->input->event = pwm_beeper_event;
+        beeper->input->close = pwm_beeper_close;
 
         input_set_drvdata(beeper->input, beeper);
 
@@ -135,7 +166,6 @@ static int pwm_beeper_remove(struct platform_device *pdev)
 
         input_unregister_device(beeper->input);
 
-        pwm_disable(beeper->pwm);
         pwm_free(beeper->pwm);
 
         kfree(beeper);
@@ -147,8 +177,7 @@ static int __maybe_unused pwm_beeper_suspend(struct device *dev)
 {
         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 
-        if (beeper->period)
-                pwm_disable(beeper->pwm);
+        pwm_beeper_stop(beeper);
 
         return 0;
 }
@@ -157,10 +186,8 @@ static int __maybe_unused pwm_beeper_resume(struct device *dev)
 {
         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 
-        if (beeper->period) {
-                pwm_config(beeper->pwm, beeper->period / 2, beeper->period);
-                pwm_enable(beeper->pwm);
-        }
+        if (beeper->period)
+                __pwm_beeper_set(beeper);
 
         return 0;
 }