Hi Heinrich,
On 26.01.2021 12:10, Heinrich Schuchardt wrote:
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?
No I don't. button_adc_bind() binds to the root node with 'adc-keys' compatible, while the dev_for_each_subnode() loop instantiates driver for each subnode, so the button_adc_probe() is called for each defined key. I've copied this pattern from gpio-keys driver.
...
Here is the related code:
+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, +};
Best regards