Re: [PATCH v5 2/4] button: add a simple Analog to Digital Converter device based button driver

On 1/26/21 10:50 AM, Marek Szyprowski wrote:

Add a simple Analog to Digital Converter device based button driver. This driver binds to the 'adc-keys' device tree node.

Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com

drivers/button/Kconfig | 8 ++ drivers/button/Makefile | 1 + drivers/button/button-adc.c | 156 ++++++++++++++++++++++++++++++++++++ 3 files changed, 165 insertions(+) create mode 100644 drivers/button/button-adc.c

diff --git a/drivers/button/Kconfig b/drivers/button/Kconfig index 6b3ec7e55d..6db3c5e93a 100644 --- a/drivers/button/Kconfig +++ b/drivers/button/Kconfig @@ -9,6 +9,14 @@ config BUTTON can provide access to board-specific buttons. Use of the device tree for configuration is encouraged.

+config BUTTON_ADC

• bool "Button adc"
• depends on BUTTON
• help

•  Enable support for buttons which are connected to Analog to Digital
  

•  Converter device. The ADC driver must use driver model. Buttons are
  

•  configured using the device tree.
  

• config BUTTON_GPIO bool "Button gpio" depends on BUTTON

diff --git a/drivers/button/Makefile b/drivers/button/Makefile index fcc10ebe8d..bbd18af149 100644 --- a/drivers/button/Makefile +++ b/drivers/button/Makefile @@ -3,4 +3,5 @@ # Copyright (C) 2020 Philippe Reynes philippe.reynes@softathome.com

obj-$(CONFIG_BUTTON) += button-uclass.o +obj-$(CONFIG_BUTTON_ADC) += button-adc.o obj-$(CONFIG_BUTTON_GPIO) += button-gpio.o diff --git a/drivers/button/button-adc.c b/drivers/button/button-adc.c new file mode 100644 index 0000000000..1901d59a0e --- /dev/null +++ b/drivers/button/button-adc.c @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (C) 2021 Samsung Electronics Co., Ltd.

• • http://www.samsung.com
    

• • Author: Marek Szyprowski m.szyprowski@samsung.com
• */

+#include <common.h> +#include <adc.h> +#include <button.h> +#include <log.h> +#include <dm.h> +#include <dm/lists.h> +#include <dm/of_access.h> +#include <dm/uclass-internal.h>

+/**

• • struct button_adc_priv - private data for button-adc driver.
• • @adc: Analog to Digital Converter device to which button is connected.
• • @channel: channel of the ADC device to probe the button state.
• • @min: minimal raw ADC sample value to consider button as pressed.
• • @max: maximal raw ADC sample value to consider button as pressed.
• */

+struct button_adc_priv {

• struct udevice *adc;
• int channel;
• int min;
• int max;

+};

+static enum button_state_t button_adc_get_state(struct udevice *dev) +{

• struct button_adc_priv *priv = dev_get_priv(dev);
• unsigned int val;
• int ret;
• ret = adc_start_channel(priv->adc, priv->channel);
• if (ret)

• return ret;
  

• ret = adc_channel_data(priv->adc, priv->channel, &val);
• if (ret)

• return ret;
  

• if (ret == 0)

• return (val >= priv->min && val < priv->max) ?
  

• 	BUTTON_ON : BUTTON_OFF;
  

• return ret;

+}

+static int button_adc_probe(struct udevice *dev) +{

• struct button_uc_plat *uc_plat = dev_get_uclass_plat(dev);
• struct button_adc_priv *priv = dev_get_priv(dev);
• struct ofnode_phandle_args args;
• u32 treshold, up_treshold, t;
• unsigned int mask;
• ofnode node;
• int ret, vdd;
• /* Ignore the top-level button node */
• if (!uc_plat->label)

• return 0;
  

• ret = dev_read_phandle_with_args(dev->parent, "io-channels",

• 			 "#io-channel-cells", 0, 0, &args);
  

• if (ret)

• return ret;
  

• ret = uclass_get_device_by_ofnode(UCLASS_ADC, args.node, &priv->adc);
• if (ret)

• return ret;
  

• ret = ofnode_read_u32(dev_ofnode(dev->parent),

• 	      "keyup-threshold-microvolt", &up_treshold);
  

• if (ret)

• return ret;
  

• ret = ofnode_read_u32(dev_ofnode(dev), "press-threshold-microvolt",

• 	      &treshold);
  

• if (ret)

• return ret;
  

• dev_for_each_subnode(node, dev->parent) {

• ret = ofnode_read_u32(dev_ofnode(dev),
  

• 		      "press-threshold-microvolt", &t);
  

• if (ret)
  

• 	return ret;
  

• if (t > treshold)
  

• 	up_treshold = t;
  

Linux' Documentation/devicetree/bindings/input/adc-keys.txt describes that one virtual key is created per sub-node.

If I read your code correctly, this is not what you are implementing. Instead you only define a single key per adc-keys node.

Why are your deviating from the bindings document?

Best regards

Heinrich

• }
• ret = adc_vdd_value(priv->adc, &vdd);
• if (ret)

• return ret;
  

• ret = adc_data_mask(priv->adc, &mask);
• if (ret)

• return ret;
  

• priv->channel = args.args[0];
• priv->min = mask * (treshold / 1000) / (vdd / 1000);
• priv->max = mask * (up_treshold / 1000) / (vdd / 1000);
• return ret;

+}

+static int button_adc_bind(struct udevice *parent) +{

• struct udevice *dev;
• ofnode node;
• int ret;
• dev_for_each_subnode(node, parent) {

• struct button_uc_plat *uc_plat;
  

• const char *label;
  

• label = ofnode_read_string(node, "label");
  

• if (!label) {
  

• 	debug("%s: node %s has no label\n", __func__,
  

• 	      ofnode_get_name(node));
  

• 	return -EINVAL;
  

• }
  

• ret = device_bind_driver_to_node(parent, "button_adc",
  

• 				 ofnode_get_name(node),
  

• 				 node, &dev);
  

• if (ret)
  

• 	return ret;
  

• uc_plat = dev_get_uclass_plat(dev);
  

• uc_plat->label = label;
  

• }
• return 0;

+}

+static const struct button_ops button_adc_ops = {

• .get_state = button_adc_get_state,

+};

+static const struct udevice_id button_adc_ids[] = {

• { .compatible = "adc-keys" },
• { }

+};

+U_BOOT_DRIVER(button_adc) = {

• .name = "button_adc",
• .id = UCLASS_BUTTON,
• .of_match = button_adc_ids,
• .ops = &button_adc_ops,
• .priv_auto = sizeof(struct button_adc_priv),
• .bind = button_adc_bind,
• .probe = button_adc_probe,

+};