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Message-Id: <20230126091825.220646-3-manuel.traut@mt.com>
Date: Thu, 26 Jan 2023 10:18:22 +0100
From: Manuel Traut <manuel.traut@...com>
To: linux-kernel@...r.kernel.org
Cc: Frieder Schrempf <frieder.schrempf@...tron.de>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Manuel Traut <manuel.traut@...com>,
linux-input@...r.kernel.org, devicetree@...r.kernel.org
Subject: [PATCH v8 2/5] input: pwm-beeper: add feature to set volume via sysfs
From: Frieder Schrempf <frieder.schrempf@...tron.de>
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@...tron.de>
Signed-off-by: Manuel Traut <manuel.traut@...com>
Tested-by: Manuel Traut <manuel.traut@...com>
---
.../ABI/testing/sysfs-devices-pwm-beeper | 17 ++++
drivers/input/misc/pwm-beeper.c | 83 ++++++++++++++++++-
2 files changed, 99 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@...tron.de>
+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@...tron.de>
+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..865e1ec5c39d 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@...afoo.de>
+ *
+ * Copyright (C) 2016, Frieder Schrempf <frieder.schrempf@...tron.de>
+ * (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] = 8;
+ beeper->volume_levels[2] = 20;
+ beeper->volume_levels[3] = 40;
+ beeper->volume_levels[4] = 500;
+
+ beeper->volume = beeper->max_volume;
+
beeper->input = devm_input_allocate_device(dev);
if (!beeper->input) {
dev_err(dev, "Failed to allocate input device\n");
@@ -192,6 +267,12 @@ 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) {
dev_err(dev, "Failed to register input device: %d\n", error);
--
2.39.0
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