158 lines
3.6 KiB
C
158 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2021 Samsung Electronics Co., Ltd.
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* http://www.samsung.com
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* Author: Marek Szyprowski <m.szyprowski@samsung.com>
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*/
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#include <common.h>
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#include <adc.h>
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#include <button.h>
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#include <log.h>
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#include <dm.h>
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#include <dm/lists.h>
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#include <dm/of_access.h>
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#include <dm/uclass-internal.h>
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/**
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* struct button_adc_priv - private data for button-adc driver.
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*
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* @adc: Analog to Digital Converter device to which button is connected.
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* @channel: channel of the ADC device to probe the button state.
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* @min: minimal uV value to consider button as pressed.
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* @max: maximal uV value to consider button as pressed.
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*/
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struct button_adc_priv {
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struct udevice *adc;
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int channel;
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int min;
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int max;
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};
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static enum button_state_t button_adc_get_state(struct udevice *dev)
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{
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struct button_adc_priv *priv = dev_get_priv(dev);
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unsigned int val;
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int ret, uV;
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ret = adc_start_channel(priv->adc, priv->channel);
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if (ret)
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return ret;
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ret = adc_channel_data(priv->adc, priv->channel, &val);
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if (ret)
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return ret;
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ret = adc_raw_to_uV(priv->adc, val, &uV);
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if (ret)
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return ret;
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return (uV >= priv->min && uV < priv->max) ? BUTTON_ON : BUTTON_OFF;
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}
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static int button_adc_of_to_plat(struct udevice *dev)
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{
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struct button_uc_plat *uc_plat = dev_get_uclass_plat(dev);
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struct button_adc_priv *priv = dev_get_priv(dev);
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struct ofnode_phandle_args args;
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u32 down_threshold = 0, up_threshold, voltage, t;
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ofnode node;
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int ret;
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/* Ignore the top-level button node */
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if (!uc_plat->label)
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return 0;
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ret = dev_read_phandle_with_args(dev->parent, "io-channels",
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"#io-channel-cells", 0, 0, &args);
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if (ret)
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return ret;
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ret = uclass_get_device_by_ofnode(UCLASS_ADC, args.node, &priv->adc);
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if (ret)
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return ret;
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ret = ofnode_read_u32(dev_ofnode(dev->parent),
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"keyup-threshold-microvolt", &up_threshold);
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if (ret)
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return ret;
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ret = ofnode_read_u32(dev_ofnode(dev), "press-threshold-microvolt",
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&voltage);
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if (ret)
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return ret;
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dev_for_each_subnode(node, dev->parent) {
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ret = ofnode_read_u32(node, "press-threshold-microvolt", &t);
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if (ret)
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return ret;
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if (t > voltage && t < up_threshold)
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up_threshold = t;
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else if (t < voltage && t > down_threshold)
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down_threshold = t;
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}
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priv->channel = args.args[0];
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/*
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* Define the voltage range such that the button is only pressed
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* when the voltage is closest to its own press-threshold-microvolt
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*/
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if (down_threshold == 0)
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priv->min = 0;
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else
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priv->min = down_threshold + (voltage - down_threshold) / 2;
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priv->max = voltage + (up_threshold - voltage) / 2;
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return ret;
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}
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static int button_adc_bind(struct udevice *parent)
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{
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struct udevice *dev;
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ofnode node;
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int ret;
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dev_for_each_subnode(node, parent) {
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struct button_uc_plat *uc_plat;
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const char *label;
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label = ofnode_read_string(node, "label");
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if (!label) {
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debug("%s: node %s has no label\n", __func__,
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ofnode_get_name(node));
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return -EINVAL;
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}
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ret = device_bind_driver_to_node(parent, "button_adc",
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ofnode_get_name(node),
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node, &dev);
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if (ret)
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return ret;
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uc_plat = dev_get_uclass_plat(dev);
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uc_plat->label = label;
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}
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return 0;
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}
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static const struct button_ops button_adc_ops = {
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.get_state = button_adc_get_state,
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};
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static const struct udevice_id button_adc_ids[] = {
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{ .compatible = "adc-keys" },
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{ }
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};
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U_BOOT_DRIVER(button_adc) = {
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.name = "button_adc",
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.id = UCLASS_BUTTON,
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.of_match = button_adc_ids,
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.ops = &button_adc_ops,
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.priv_auto = sizeof(struct button_adc_priv),
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.bind = button_adc_bind,
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.of_to_plat = button_adc_of_to_plat,
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};
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