button: add a simple Analog to Digital Converter device based button driver

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>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

diff --git a/drivers/button/Kconfig b/drivers/button/Kconfig
index 6b3ec7e55de539fb349a7a2c4f30d3ae93a78176..6db3c5e93a48557e8cd882fbba9252cf91efa304 100644 (file)
--- 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 fcc10ebe8db6fbaef83683241affa262713a2fb4..bbd18af14940ed469309d2cb73727639df188a80 100644 (file)
--- 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 (file)
index 0000000..eed8656
--- /dev/null
+++ b/drivers/button/button-adc.c
@@ -0,0 +1,146 @@
+// 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 uV value to consider button as pressed.
+ * @max: maximal uV 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, uV;
+
+       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_raw_to_uV(priv->adc, val, &uV);
+       if (ret)
+               return ret;
+
+       return (uV >= priv->min && uV < priv->max) ? BUTTON_ON : BUTTON_OFF;
+}
+
+static int button_adc_of_to_plat(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;
+       ofnode node;
+       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_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(node, "press-threshold-microvolt", &t);
+               if (ret)
+                       return ret;
+
+               if (t > treshold)
+                       up_treshold = t;
+       }
+
+       priv->channel = args.args[0];
+       priv->min = treshold;
+       priv->max = up_treshold;
+
+       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,
+       .of_to_plat     = button_adc_of_to_plat,
+};