[PATCH 4/6] button: add a simple ADC-based button driver

[Simon Glass]

Hi Marek,

On Mon, 14 Dec 2020 at 04:25, Marek Szyprowski <m.szyprowski at samsung.com> wrote:
>
> Add a simple ADC-based button driver. This driver binds to the 'adc-keys'
> device tree node.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> Change-Id: I6da7101eff3ce53766d899f49f5839d728d52fb3
> ---
>  drivers/button/Kconfig      |   8 +++
>  drivers/button/Makefile     |   1 +
>  drivers/button/button-adc.c | 117 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 126 insertions(+)
>  create mode 100644 drivers/button/button-adc.c
>
> diff --git a/drivers/button/Kconfig b/drivers/button/Kconfig
> index 6b3ec7e55de..283367f2bd3 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 ADC lines. 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 fcc10ebe8db..bbd18af1494 100644
> --- a/drivers/button/Makefile
> +++ b/drivers/button/Makefile
> @@ -3,4 +3,5 @@
>  # Copyright (C) 2020 Philippe Reynes <philippe.reynes at 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 00000000000..086c676c02a
> --- /dev/null
> +++ b/drivers/button/button-adc.c
> @@ -0,0 +1,117 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 Samsung Electronics Co., Ltd.
> + *             http://www.samsung.com
> + * Author: Marek Szyprowski <m.szyprowski at samsung.com>
> + */
> +
> +#include <common.h>
> +#include <button.h>
> +#include <dm.h>
> +#include <dm/lists.h>
> +#include <dm/uclass-internal.h>
> +#include <log.h>
> +#include <adc.h>

Please check header order

https://www.denx.de/wiki/U-Boot/CodingStyle

> +
> +struct button_adc_priv {
> +       struct udevice *adc;
> +       int channel;

comments

> +};
> +
> +static enum button_state_t button_adc_get_state(struct udevice *dev)
> +{
> +       struct button_adc_priv *priv = dev_get_priv(dev);
> +       unsigned int val, mask;
> +       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;
> +
> +       ret = adc_data_mask(priv->adc, &mask);
> +       if (ret)
> +               return ret;
> +
> +       /* getting state is simplified a bit */
> +       if (ret == 0)
> +               return (val < mask / 2) ? BUTTON_ON : BUTTON_OFF;
> +
> +       return ret;
> +}
> +
> +static int button_adc_probe(struct udevice *dev)
> +{
> +       struct button_uc_plat *uc_plat = dev_get_uclass_platdata(dev);
> +       struct button_adc_priv *priv = dev_get_priv(dev);
> +       struct ofnode_phandle_args args;
> +       int ret;
> +
> +       /* 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_name(UCLASS_ADC, ofnode_get_name(args.node),
> +                                       &priv->adc);

How about uclass_get_device_by_ofnode() ?

> +       if (ret)
> +               return ret;
> +
> +       priv->channel = args.args[0];
> +
> +       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_platdata(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" },

Please add the binding file for this.

> +       { }
> +};
> +
> +U_BOOT_DRIVER(button_adc) = {
> +       .name           = "button_adc",
> +       .id             = UCLASS_BUTTON,
> +       .of_match       = button_adc_ids,
> +       .ops            = &button_adc_ops,
> +       .priv_auto_alloc_size = sizeof(struct button_adc_priv),
> +       .bind           = button_adc_bind,
> +       .probe          = button_adc_probe,
> +};
> --
> 2.17.1
>

Regards,
Simon