[PATCH v2 1/2] input: adc-keys: add DT binding documentation

[PATCH v2 1/2] input: adc-keys: add DT binding documentation

[Alexandre Belloni]

Add documentation for ADC keys

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
Changes in v2:
 - fix title
 - use keyup-threshold-mvolt and press-threshold-mvolt instead of
   voltage-keyup-mvolt and voltage-mvolt.

 .../devicetree/bindings/input/adc-keys.txt         | 45 ++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/adc-keys.txt

diff --git a/Documentation/devicetree/bindings/input/adc-keys.txt b/Documentation/devicetree/bindings/input/adc-keys.txt
new file mode 100644
index 000000000000..e43b8979b85a
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/adc-keys.txt
@@ -0,0 +1,45 @@
+ADC attached resistor ladder buttons
+------------------------------------
+
+Required properties:
+ - compatible: "adc-keys"
+ - io-channels: Phandle to an ADC channel
+ - io-channel-names = "buttons";
+ - keyup-threshold-mvolt: Voltage at which all the keys are considered up.
+
+Each key is represented as a sub-node of "adc-keys":
+
+Required subnode-properties:
+	- label: Descriptive name of the key.
+	- linux,code: Keycode to emit.
+	- press-threshold-mvolt: Voltage adc input when this key is pressed.
+
+Example:
+
+#include <dt-bindings/input/input.h>
+
+	adc-keys {
+		compatible = "adc-keys";
+		io-channels = <&lradc 0>;
+		io-channel-names = "buttons";
+		keyup-threshold-mvolt = <2000>;
+
+		button@1500 {
+			label = "Volume Up";
+			linux,code = <KEY_VOLUMEUP>;
+			press-threshold-mvolt = <1500>;
+		};
+
+		button@1000 {
+			label = "Volume Down";
+			linux,code = <KEY_VOLUMEDOWN>;
+			press-threshold-mvolt = <1000>;
+		};
+
+		button@500 {
+			label = "Enter";
+			linux,code = <KEY_ENTER>;
+			press-threshold-mvolt = <500>;
+		};
+	};
+
-- 
2.8.1

[PATCH v2 2/2] input: add ADC resistor ladder driver

[Alexandre Belloni]

A common way of multiplexing buttons on a single input in cheap devices is
to use a resistor ladder on an ADC. This driver supports that configuration
by polling an ADC channel provided by IIO.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
Changes in v2:
 - removed dependency on COMPILE_TEST which is not useful anyway
 - use new bindings

 drivers/input/keyboard/Kconfig    |  15 +++
 drivers/input/keyboard/Makefile   |   1 +
 drivers/input/keyboard/adc-keys.c | 210 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 226 insertions(+)
 create mode 100644 drivers/input/keyboard/adc-keys.c

diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index 509608c95994..4cf042cc5e63 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -12,6 +12,21 @@ menuconfig INPUT_KEYBOARD
 
 if INPUT_KEYBOARD
 
+config KEYBOARD_ADC
+	tristate "ADC ladder Buttons"
+	depends on IIO
+	select INPUT_POLLDEV
+	help
+	  This driver implements support for buttons connected
+	  to an ADC using a resistor ladder.
+
+	  Say Y here if your device has such buttons connected to an ADC.  Your
+	  board-specific setup logic must also provide a configuration data
+	  saying mapping voltages to buttons.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called adc_keys.
+
 config KEYBOARD_ADP5520
 	tristate "Keypad Support for ADP5520 PMIC"
 	depends on PMIC_ADP5520
diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index 1d416ddf84e4..d9f4cfcf3410 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile
@@ -4,6 +4,7 @@
 
 # Each configuration option enables a list of files.
 
+obj-$(CONFIG_KEYBOARD_ADC)		+= adc-keys.o
 obj-$(CONFIG_KEYBOARD_ADP5520)		+= adp5520-keys.o
 obj-$(CONFIG_KEYBOARD_ADP5588)		+= adp5588-keys.o
 obj-$(CONFIG_KEYBOARD_ADP5589)		+= adp5589-keys.o
diff --git a/drivers/input/keyboard/adc-keys.c b/drivers/input/keyboard/adc-keys.c
new file mode 100644
index 000000000000..cf299ff517a0
--- /dev/null
+++ b/drivers/input/keyboard/adc-keys.c
@@ -0,0 +1,210 @@
+/* Input driver for resistor ladder connected on ADC
+ *
+ * Copyright (c) 2016 Alexandre Belloni
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/input.h>
+#include <linux/input-polldev.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/types.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+
+struct adc_keys_button {
+	u32 voltage;
+	u32 keycode;
+};
+
+struct adc_keys_state {
+	struct iio_channel *channel;
+	u32 num_keys;
+	u32 last_key;
+	u32 keyup_voltage;
+	struct adc_keys_button *map;
+};
+
+static void adc_keys_poll(struct input_polled_dev *dev)
+{
+	struct adc_keys_state *st = dev->private;
+	int i, value, ret;
+	u32 diff, closest = 0xffffffff;
+	int keycode = 0;
+
+	ret = iio_read_channel_processed(st->channel, &value);
+	if (ret < 0) {
+		if (st->last_key) {
+			input_report_key(dev->input, st->last_key, 0);
+			input_sync(dev->input);
+			st->last_key = 0;
+		}
+		return;
+	}
+
+	for (i = 0; i < st->num_keys; i++) {
+		diff = abs(st->map[i].voltage - value);
+		if (diff < closest) {
+			closest = diff;
+			keycode = st->map[i].keycode;
+		}
+	}
+
+	if (abs(st->keyup_voltage - value) < closest) {
+		input_report_key(dev->input, st->last_key, 0);
+		st->last_key = 0;
+	} else {
+		if (st->last_key && st->last_key != keycode)
+			input_report_key(dev->input, st->last_key, 0);
+		input_report_key(dev->input, keycode, 1);
+		st->last_key = keycode;
+	}
+
+	input_sync(dev->input);
+}
+
+static int adc_keys_load_dt_keymap(struct device *dev,
+				   struct adc_keys_state *st)
+{
+	struct device_node *pp, *np = dev->of_node;
+	int i;
+
+	st->num_keys = of_get_child_count(np);
+	if (st->num_keys == 0) {
+		dev_err(dev, "keymap is missing\n");
+		return -EINVAL;
+	}
+
+	st->map = devm_kmalloc_array(dev, st->num_keys, sizeof(*st->map),
+				     GFP_KERNEL);
+	if (!st->map)
+		return -ENOMEM;
+
+	i = 0;
+	for_each_child_of_node(np, pp) {
+		struct adc_keys_button *map = &st->map[i];
+
+		if (of_property_read_u32(pp, "press-threshold-mvolt",
+					 &map->voltage)) {
+			dev_err(dev, "%s: Invalid or missing voltage\n",
+				pp->name);
+			return -EINVAL;
+		}
+
+		if (of_property_read_u32(pp, "linux,code", &map->keycode)) {
+			dev_err(dev, "%s: Invalid or missing linux,code\n",
+				pp->name);
+			return -EINVAL;
+		}
+
+		i++;
+	}
+
+	return 0;
+}
+
+static int adc_keys_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	struct adc_keys_state *st;
+	struct input_polled_dev *poll_dev = NULL;
+	struct input_dev *input;
+	enum iio_chan_type type;
+	int i, value, ret;
+
+	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	st->channel = devm_iio_channel_get(dev, "buttons");
+	if (IS_ERR(st->channel))
+		return PTR_ERR(st->channel);
+
+	if (!st->channel->indio_dev)
+		return -ENODEV;
+
+	ret = iio_get_channel_type(st->channel, &type);
+	if (ret < 0)
+		return ret;
+
+	if (type != IIO_VOLTAGE) {
+		dev_err(dev, "Incompatible channel type %d\n", type);
+		return -EINVAL;
+	}
+
+	if (of_property_read_u32(node, "keyup-threshold-mvolt",
+				 &st->keyup_voltage)) {
+		dev_err(dev, "Invalid or missing keyup voltage\n");
+		return -EINVAL;
+	}
+
+	ret = adc_keys_load_dt_keymap(dev, st);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, st);
+
+	poll_dev = devm_input_allocate_polled_device(dev);
+	if (!poll_dev) {
+		dev_err(dev, "failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	if (!of_property_read_u32(node, "poll-interval", &value))
+		poll_dev->poll_interval = value;
+	poll_dev->poll = adc_keys_poll;
+	poll_dev->private = st;
+
+	input = poll_dev->input;
+
+	input->name = pdev->name;
+	input->phys = "adc-keys/input0";
+	input->dev.parent = &pdev->dev;
+
+	input->id.bustype = BUS_HOST;
+	input->id.vendor = 0x0001;
+	input->id.product = 0x0001;
+	input->id.version = 0x0100;
+
+	__set_bit(EV_KEY, input->evbit);
+	for (i = 0; i < st->num_keys; i++)
+		__set_bit(st->map[i].keycode, input->keybit);
+
+	if (!!of_get_property(node, "autorepeat", NULL))
+		__set_bit(EV_REP, input->evbit);
+
+	ret = input_register_polled_device(poll_dev);
+	if (ret) {
+		dev_err(dev, "Unable to register input device\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id adc_keys_of_match[] = {
+	{ .compatible = "adc-keys", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, adc_keys_of_match);
+
+static struct platform_driver __refdata adc_keys_driver = {
+	.driver = {
+		.name = "adc_keys",
+		.of_match_table = adc_keys_of_match,
+	},
+	.probe = adc_keys_probe,
+};
+
+module_platform_driver(adc_keys_driver);
+
+MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
+MODULE_DESCRIPTION("Input driver for resistor ladder connected on ADC");
+MODULE_LICENSE("GPL v2");
-- 
2.8.1

Re: [PATCH v2 2/2] input: add ADC resistor ladder driver

[Jonathan Cameron]

On 09/07/16 02:24, Alexandre Belloni wrote:
> A common way of multiplexing buttons on a single input in cheap devices is
> to use a resistor ladder on an ADC. This driver supports that configuration
> by polling an ADC channel provided by IIO.
> 
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
> ---
> Changes in v2:
>  - removed dependency on COMPILE_TEST which is not useful anyway
>  - use new bindings
> 
>  drivers/input/keyboard/Kconfig    |  15 +++
>  drivers/input/keyboard/Makefile   |   1 +
>  drivers/input/keyboard/adc-keys.c | 210 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 226 insertions(+)
>  create mode 100644 drivers/input/keyboard/adc-keys.c
> 
> diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
> index 509608c95994..4cf042cc5e63 100644
> --- a/drivers/input/keyboard/Kconfig
> +++ b/drivers/input/keyboard/Kconfig
> @@ -12,6 +12,21 @@ menuconfig INPUT_KEYBOARD
>  
>  if INPUT_KEYBOARD
>  
> +config KEYBOARD_ADC
> +	tristate "ADC ladder Buttons"
> +	depends on IIO
> +	select INPUT_POLLDEV
> +	help
> +	  This driver implements support for buttons connected
> +	  to an ADC using a resistor ladder.
> +
> +	  Say Y here if your device has such buttons connected to an ADC.  Your
> +	  board-specific setup logic must also provide a configuration data
> +	  saying mapping voltages to buttons.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called adc_keys.
> +
>  config KEYBOARD_ADP5520
>  	tristate "Keypad Support for ADP5520 PMIC"
>  	depends on PMIC_ADP5520
> diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
> index 1d416ddf84e4..d9f4cfcf3410 100644
> --- a/drivers/input/keyboard/Makefile
> +++ b/drivers/input/keyboard/Makefile
> @@ -4,6 +4,7 @@
>  
>  # Each configuration option enables a list of files.
>  
> +obj-$(CONFIG_KEYBOARD_ADC)		+= adc-keys.o
>  obj-$(CONFIG_KEYBOARD_ADP5520)		+= adp5520-keys.o
>  obj-$(CONFIG_KEYBOARD_ADP5588)		+= adp5588-keys.o
>  obj-$(CONFIG_KEYBOARD_ADP5589)		+= adp5589-keys.o
> diff --git a/drivers/input/keyboard/adc-keys.c b/drivers/input/keyboard/adc-keys.c
> new file mode 100644
> index 000000000000..cf299ff517a0
> --- /dev/null
> +++ b/drivers/input/keyboard/adc-keys.c
> @@ -0,0 +1,210 @@
> +/* Input driver for resistor ladder connected on ADC
> + *
> + * Copyright (c) 2016 Alexandre Belloni
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/err.h>
> +#include <linux/input.h>
> +#include <linux/input-polldev.h>
> +#include <linux/iio/consumer.h>
> +#include <linux/iio/types.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +
> +struct adc_keys_button {
> +	u32 voltage;
> +	u32 keycode;
> +};
> +
> +struct adc_keys_state {
> +	struct iio_channel *channel;
> +	u32 num_keys;
> +	u32 last_key;
> +	u32 keyup_voltage;
> +	struct adc_keys_button *map;
> +};
> +
> +static void adc_keys_poll(struct input_polled_dev *dev)
> +{
> +	struct adc_keys_state *st = dev->private;
> +	int i, value, ret;
> +	u32 diff, closest = 0xffffffff;
> +	int keycode = 0;
> +
> +	ret = iio_read_channel_processed(st->channel, &value);
> +	if (ret < 0) {
> +		if (st->last_key) {
> +			input_report_key(dev->input, st->last_key, 0);
> +			input_sync(dev->input);
> +			st->last_key = 0;
> +		}
> +		return;
> +	}
> +
> +	for (i = 0; i < st->num_keys; i++) {
> +		diff = abs(st->map[i].voltage - value);
> +		if (diff < closest) {
> +			closest = diff;
> +			keycode = st->map[i].keycode;
> +		}
> +	}
> +
> +	if (abs(st->keyup_voltage - value) < closest) {
> +		input_report_key(dev->input, st->last_key, 0);
> +		st->last_key = 0;
> +	} else {
> +		if (st->last_key && st->last_key != keycode)
> +			input_report_key(dev->input, st->last_key, 0);
> +		input_report_key(dev->input, keycode, 1);
> +		st->last_key = keycode;
> +	}
> +
> +	input_sync(dev->input);
> +}
> +
> +static int adc_keys_load_dt_keymap(struct device *dev,
> +				   struct adc_keys_state *st)
> +{
> +	struct device_node *pp, *np = dev->of_node;
> +	int i;
> +
> +	st->num_keys = of_get_child_count(np);
> +	if (st->num_keys == 0) {
> +		dev_err(dev, "keymap is missing\n");
> +		return -EINVAL;
> +	}
> +
> +	st->map = devm_kmalloc_array(dev, st->num_keys, sizeof(*st->map),
> +				     GFP_KERNEL);
> +	if (!st->map)
> +		return -ENOMEM;
> +
> +	i = 0;
> +	for_each_child_of_node(np, pp) {
> +		struct adc_keys_button *map = &st->map[i];
> +
> +		if (of_property_read_u32(pp, "press-threshold-mvolt",
> +					 &map->voltage)) {
> +			dev_err(dev, "%s: Invalid or missing voltage\n",
> +				pp->name);
> +			return -EINVAL;
> +		}
> +
> +		if (of_property_read_u32(pp, "linux,code", &map->keycode)) {
> +			dev_err(dev, "%s: Invalid or missing linux,code\n",
> +				pp->name);
> +			return -EINVAL;
> +		}
> +
> +		i++;
> +	}
> +
> +	return 0;
> +}
> +
> +static int adc_keys_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *node = dev->of_node;
> +	struct adc_keys_state *st;
> +	struct input_polled_dev *poll_dev = NULL;
> +	struct input_dev *input;
> +	enum iio_chan_type type;
> +	int i, value, ret;
> +
> +	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
> +	if (!st)
> +		return -ENOMEM;
> +
> +	st->channel = devm_iio_channel_get(dev, "buttons");
> +	if (IS_ERR(st->channel))
> +		return PTR_ERR(st->channel);
> +
> +	if (!st->channel->indio_dev)
> +		return -ENODEV;
> +
> +	ret = iio_get_channel_type(st->channel, &type);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (type != IIO_VOLTAGE) {
> +		dev_err(dev, "Incompatible channel type %d\n", type);
> +		return -EINVAL;
> +	}
> +
> +	if (of_property_read_u32(node, "keyup-threshold-mvolt",
> +				 &st->keyup_voltage)) {
> +		dev_err(dev, "Invalid or missing keyup voltage\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = adc_keys_load_dt_keymap(dev, st);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, st);
> +
> +	poll_dev = devm_input_allocate_polled_device(dev);
> +	if (!poll_dev) {
> +		dev_err(dev, "failed to allocate input device\n");
> +		return -ENOMEM;
> +	}
> +
> +	if (!of_property_read_u32(node, "poll-interval", &value))
> +		poll_dev->poll_interval = value;
> +	poll_dev->poll = adc_keys_poll;
> +	poll_dev->private = st;
> +
> +	input = poll_dev->input;
> +
> +	input->name = pdev->name;
> +	input->phys = "adc-keys/input0";
> +	input->dev.parent = &pdev->dev;
> +
> +	input->id.bustype = BUS_HOST;
> +	input->id.vendor = 0x0001;
> +	input->id.product = 0x0001;
> +	input->id.version = 0x0100;
> +
> +	__set_bit(EV_KEY, input->evbit);
> +	for (i = 0; i < st->num_keys; i++)
> +		__set_bit(st->map[i].keycode, input->keybit);
> +
> +	if (!!of_get_property(node, "autorepeat", NULL))
> +		__set_bit(EV_REP, input->evbit);
> +
> +	ret = input_register_polled_device(poll_dev);
> +	if (ret) {
> +		dev_err(dev, "Unable to register input device\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id adc_keys_of_match[] = {
> +	{ .compatible = "adc-keys", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, adc_keys_of_match);
> +
> +static struct platform_driver __refdata adc_keys_driver = {
> +	.driver = {
> +		.name = "adc_keys",
> +		.of_match_table = adc_keys_of_match,
> +	},
> +	.probe = adc_keys_probe,
> +};
> +
> +module_platform_driver(adc_keys_driver);
> +
> +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
> +MODULE_DESCRIPTION("Input driver for resistor ladder connected on ADC");
> +MODULE_LICENSE("GPL v2");
> 

Re: [PATCH v2 1/2] input: adc-keys: add DT binding documentation

[Jonathan Cameron]

On 09/07/16 02:24, Alexandre Belloni wrote:
> Add documentation for ADC keys
> 
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
I'm seeing a few more properties in the driver.  They may be generic
input ones, but should still be listed here...

autorepeat for example.

> ---
> Changes in v2:
>  - fix title
>  - use keyup-threshold-mvolt and press-threshold-mvolt instead of
>    voltage-keyup-mvolt and voltage-mvolt.
> 
>  .../devicetree/bindings/input/adc-keys.txt         | 45 ++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/adc-keys.txt
> 
> diff --git a/Documentation/devicetree/bindings/input/adc-keys.txt b/Documentation/devicetree/bindings/input/adc-keys.txt
> new file mode 100644
> index 000000000000..e43b8979b85a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/adc-keys.txt
> @@ -0,0 +1,45 @@
> +ADC attached resistor ladder buttons
> +------------------------------------
> +
> +Required properties:
> + - compatible: "adc-keys"
> + - io-channels: Phandle to an ADC channel
> + - io-channel-names = "buttons";
> + - keyup-threshold-mvolt: Voltage at which all the keys are considered up.
> +
> +Each key is represented as a sub-node of "adc-keys":
> +
> +Required subnode-properties:
> +	- label: Descriptive name of the key.
> +	- linux,code: Keycode to emit.
> +	- press-threshold-mvolt: Voltage adc input when this key is pressed.
> +
> +Example:
> +
> +#include <dt-bindings/input/input.h>
> +
> +	adc-keys {
> +		compatible = "adc-keys";
> +		io-channels = <&lradc 0>;
> +		io-channel-names = "buttons";
> +		keyup-threshold-mvolt = <2000>;
> +
> +		button@1500 {
> +			label = "Volume Up";
> +			linux,code = <KEY_VOLUMEUP>;
> +			press-threshold-mvolt = <1500>;
> +		};
> +
> +		button@1000 {
> +			label = "Volume Down";
> +			linux,code = <KEY_VOLUMEDOWN>;
> +			press-threshold-mvolt = <1000>;
> +		};
> +
> +		button@500 {
> +			label = "Enter";
> +			linux,code = <KEY_ENTER>;
> +			press-threshold-mvolt = <500>;
> +		};
> +	};
> +
>