[PATCH 4.6 025/100] Input: pwm-beeper - fix - scheduling while atomic

Greg Kroah-Hartman
2016-05-30T21:11:02Z

From: Manfred Schlaegl <manfred.schlaegl@gmx.at>

commit f49cf3b8b4c841457244c461c66186a719e13bcc upstream.

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>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/input/misc/pwm-beeper.c | 69 +++++++++++++++++++++++++++-------------
1 file changed, 48 insertions(+), 21 deletions(-)

--- 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
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 platf
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 platf
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 plat

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_sus
{
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_res
{
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;
}