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.szyprow...@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.rey...@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.szyprow...@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,
+};
