diff mbox series

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

Message ID 20201214112437.18757-5-m.szyprowski@samsung.com
State Superseded
Headers show
Series VIM3: add support for checking 'Function' button state | expand

Commit Message

Marek Szyprowski Dec. 14, 2020, 11:24 a.m. UTC
Add a simple ADC-based button driver. This driver binds to the 'adc-keys'
device tree node.

Signed-off-by: Marek Szyprowski <m.szyprowski@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

-- 
2.17.1

Comments

Simon Glass Dec. 19, 2020, 2:28 a.m. UTC | #1
Hi Marek,

On Mon, 14 Dec 2020 at 04:25, Marek Szyprowski <m.szyprowski@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@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@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@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
Marek Szyprowski Dec. 21, 2020, 9:33 a.m. UTC | #2
Hi Simon,

On 19.12.2020 03:28, Simon Glass wrote:
> On Mon, 14 Dec 2020 at 04:25, Marek Szyprowski <m.szyprowski@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@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@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@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://protect2.fireeye.com/v1/url?k=0827922c-57bcaba3-08261963-0cc47a31307c-c2add94742a708a4&q=1&e=e6ddd072-23a6-4591-9ca7-8d41aa498536&u=https%3A%2F%2Fwww.denx.de%2Fwiki%2FU-Boot%2FCodingStyle

>

>> +

>> +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.

Do you want me to copy the 
Documentation/devicetree/bindings/input/adc-keys.txt file from Linux 
kernel to doc/device-tree-bindings/input or should I modify it somehow? 
(drop all the ignored properties?)
>> +       { }

>> +};

>> +

>> +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

>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland
Simon Glass Dec. 21, 2020, 4:46 p.m. UTC | #3
Hi Marek,

On Mon, 21 Dec 2020 at 02:34, Marek Szyprowski <m.szyprowski@samsung.com> wrote:
>

> Hi Simon,

>

> On 19.12.2020 03:28, Simon Glass wrote:

> > On Mon, 14 Dec 2020 at 04:25, Marek Szyprowski <m.szyprowski@samsung.com> wrote:

> >> Add a simple ADC-based button driver. This driver binds to the 'adc-keys'

> >> device tree node.


I think it is best to copy it exactly as is.

Regards,
Simon


> >>

> >> Signed-off-by: Marek Szyprowski <m.szyprowski@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@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@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://protect2.fireeye.com/v1/url?k=0827922c-57bcaba3-08261963-0cc47a31307c-c2add94742a708a4&q=1&e=e6ddd072-23a6-4591-9ca7-8d41aa498536&u=https%3A%2F%2Fwww.denx.de%2Fwiki%2FU-Boot%2FCodingStyle

> >

> >> +

> >> +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.

> Do you want me to copy the

> Documentation/devicetree/bindings/input/adc-keys.txt file from Linux

> kernel to doc/device-tree-bindings/input or should I modify it somehow?

> (drop all the ignored properties?)

> >> +       { }

> >> +};

> >> +

> >> +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

> >

> Best regards

> --

> Marek Szyprowski, PhD

> Samsung R&D Institute Poland

>
diff mbox series

Patch

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@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@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>
+
+struct button_adc_priv {
+	struct udevice *adc;
+	int channel;
+};
+
+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);
+	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" },
+	{ }
+};
+
+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,
+};