[PATCH v10 2/4] input: pwm-beeper: add feature to set volume via sysfs

[Manuel Traut]

From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>

Make the driver accept switching volume levels via sysfs.
This can be helpful if the beep/bell sound intensity needs
to be adapted to the environment of the device.

The volume adjustment is done by changing the duty cycle of
the pwm signal.

Add a sysfs interface with 5 default volume levels:
  0 - mute
  ..
  4 - max. volume

Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
Signed-off-by: Manuel Traut <manuel.traut@xxxxxx>
Tested-by: Manuel Traut <manuel.traut@xxxxxx>
---
 .../ABI/testing/sysfs-devices-pwm-beeper      | 17 ++++
 drivers/input/misc/pwm-beeper.c               | 96 ++++++++++++++++++-
 2 files changed, 112 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-pwm-beeper

diff --git a/Documentation/ABI/testing/sysfs-devices-pwm-beeper b/Documentation/ABI/testing/sysfs-devices-pwm-beeper
new file mode 100644
index 000000000000..d2a22516f31d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-pwm-beeper
@@ -0,0 +1,17 @@
+What:		/sys/devices/.../pwm-beeper/volume
+Date:		January 2023
+KernelVersion:
+Contact:	Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
+Description:
+		Control the volume of this pwm-beeper. Values
+		are between 0 and max_volume. This file will also
+		show the current volume level stored in the driver.
+
+What:		/sys/devices/.../pwm-beeper/max_volume
+Date:		February 2023
+KernelVersion:
+Contact:	Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
+Description:
+		This file shows the maximum volume level that can be
+		assigned to volume.
+
diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
index d6b12477748a..214d3fa0a06d 100644
--- a/drivers/input/misc/pwm-beeper.c
+++ b/drivers/input/misc/pwm-beeper.c
@@ -1,9 +1,14 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  Copyright (C) 2010, Lars-Peter Clausen <lars@xxxxxxxxxx>
+ *
+ *  Copyright (C) 2016, Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
+ *  (volume support)
+ *
  *  PWM beeper driver
  */
 
+#include <linux/device.h>
 #include <linux/input.h>
 #include <linux/regulator/consumer.h>
 #include <linux/module.h>
@@ -24,10 +29,61 @@ struct pwm_beeper {
 	unsigned int bell_frequency;
 	bool suspended;
 	bool amplifier_on;
+	unsigned int volume;
+	unsigned int *volume_levels;
+	unsigned int max_volume;
 };
 
 #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
 
+static ssize_t volume_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct pwm_beeper *beeper = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", beeper->volume);
+}
+
+static ssize_t max_volume_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct pwm_beeper *beeper = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", beeper->max_volume);
+}
+
+static ssize_t volume_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int rc;
+	struct pwm_beeper *beeper = dev_get_drvdata(dev);
+	unsigned int volume;
+
+	rc = kstrtouint(buf, 0, &volume);
+	if (rc)
+		return rc;
+
+	if (volume > beeper->max_volume)
+		return -EINVAL;
+	pr_debug("set volume to %u\n", volume);
+	beeper->volume = volume;
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(volume);
+static DEVICE_ATTR_RO(max_volume);
+
+static struct attribute *pwm_beeper_attributes[] = {
+	&dev_attr_volume.attr,
+	&dev_attr_max_volume.attr,
+	NULL,
+};
+
+static struct attribute_group pwm_beeper_attribute_group = {
+	.attrs = pwm_beeper_attributes,
+};
+
 static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)
 {
 	struct pwm_state state;
@@ -37,7 +93,7 @@ static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)
 
 	state.enabled = true;
 	state.period = period;
-	pwm_set_relative_duty_cycle(&state, 50, 100);
+	pwm_set_relative_duty_cycle(&state, beeper->volume_levels[beeper->volume], 1000);
 
 	error = pwm_apply_state(beeper->pwm, &state);
 	if (error)
@@ -126,6 +182,7 @@ static int pwm_beeper_probe(struct platform_device *pdev)
 	struct pwm_state state;
 	u32 bell_frequency;
 	int error;
+	size_t size;
 
 	beeper = devm_kzalloc(dev, sizeof(*beeper), GFP_KERNEL);
 	if (!beeper)
@@ -171,6 +228,24 @@ static int pwm_beeper_probe(struct platform_device *pdev)
 
 	beeper->bell_frequency = bell_frequency;
 
+	beeper->max_volume = 4;
+
+	size = sizeof(*beeper->volume_levels) *
+		(beeper->max_volume + 1);
+
+	beeper->volume_levels = devm_kzalloc(&(pdev->dev), size,
+		GFP_KERNEL);
+	if (!beeper->volume_levels)
+		return -ENOMEM;
+
+	beeper->volume_levels[0] = 0;
+	beeper->volume_levels[1] = 80;
+	beeper->volume_levels[2] = 200;
+	beeper->volume_levels[3] = 400;
+	beeper->volume_levels[4] = 5000;
+
+	beeper->volume = beeper->max_volume;
+
 	beeper->input = devm_input_allocate_device(dev);
 	if (!beeper->input) {
 		dev_err(dev, "Failed to allocate input device\n");
@@ -192,8 +267,15 @@ static int pwm_beeper_probe(struct platform_device *pdev)
 
 	input_set_drvdata(beeper->input, beeper);
 
+	error = sysfs_create_group(&pdev->dev.kobj, &pwm_beeper_attribute_group);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to create sysfs group: %d\n", error);
+		return error;
+	}
+
 	error = input_register_device(beeper->input);
 	if (error) {
+		sysfs_remove_group(&pdev->dev.kobj, &pwm_beeper_attribute_group);
 		dev_err(dev, "Failed to register input device: %d\n", error);
 		return error;
 	}
@@ -203,6 +285,17 @@ static int pwm_beeper_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int pwm_beeper_remove(struct platform_device *pdev)
+{
+	struct pwm_beeper *beeper;
+
+	beeper = platform_get_drvdata(pdev);
+	input_unregister_device(beeper->input);
+	sysfs_remove_group(&pdev->dev.kobj, &pwm_beeper_attribute_group);
+
+	return 0;
+}
+
 static int __maybe_unused pwm_beeper_suspend(struct device *dev)
 {
 	struct pwm_beeper *beeper = dev_get_drvdata(dev);
@@ -248,6 +341,7 @@ MODULE_DEVICE_TABLE(of, pwm_beeper_match);
 
 static struct platform_driver pwm_beeper_driver = {
 	.probe	= pwm_beeper_probe,
+	.remove	= pwm_beeper_remove,
 	.driver = {
 		.name	= "pwm-beeper",
 		.pm	= &pwm_beeper_pm_ops,
-- 
2.39.1