[v3,2/2] Input: add driver for power button on Dell Wyse 3020

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 362e8a01980cd..e7bb572e15182 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -73,6 +73,17 @@  config INPUT_AD714X_SPI
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad714x-spi.
 
+config INPUT_ARIEL_PWRBUTTON
+	tristate "Dell Wyse 3020 Power Button Driver"
+	depends on SPI
+	depends on MACH_MMP3_DT || COMPILE_TEST
+	help
+	  Say Y to enable support for reporting power button status on
+	  on Dell Wyse 3020 ("Ariel") thin client.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called ariel-pwrbutton.
+
 config INPUT_ARIZONA_HAPTICS
 	tristate "Arizona haptics support"
 	depends on MFD_ARIZONA && SND_SOC
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index a48e5f2d859d4..062cea9f181c9 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -15,6 +15,7 @@  obj-$(CONFIG_INPUT_ADXL34X)		+= adxl34x.o
 obj-$(CONFIG_INPUT_ADXL34X_I2C)		+= adxl34x-i2c.o
 obj-$(CONFIG_INPUT_ADXL34X_SPI)		+= adxl34x-spi.o
 obj-$(CONFIG_INPUT_APANEL)		+= apanel.o
+obj-$(CONFIG_INPUT_ARIEL_PWRBUTTON)	+= ariel-pwrbutton.o
 obj-$(CONFIG_INPUT_ARIZONA_HAPTICS)	+= arizona-haptics.o
 obj-$(CONFIG_INPUT_ATI_REMOTE2)		+= ati_remote2.o
 obj-$(CONFIG_INPUT_ATLAS_BTNS)		+= atlas_btns.o
diff --git a/drivers/input/misc/ariel-pwrbutton.c b/drivers/input/misc/ariel-pwrbutton.c
new file mode 100644
index 0000000000000..eda86ab552b9c
--- /dev/null
+++ b/drivers/input/misc/ariel-pwrbutton.c
@@ -0,0 +1,169 @@ 
+// SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later
+/*
+ * Dell Wyse 3020 a.k.a. "Ariel" Power Button Driver
+ *
+ * Copyright (C) 2020 Lubomir Rintel
+ */
+
+#include <linux/device.h>
+#include <linux/gfp.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#define RESP_COUNTER(response)	(response.header & 0x3)
+#define RESP_SIZE(response)	((response.header >> 2) & 0x3)
+#define RESP_TYPE(response)	((response.header >> 4) & 0xf)
+
+struct ec_input_response {
+	u8 reserved;
+	u8 header;
+	u8 data[3];
+} __packed;
+
+struct ariel_pwrbutton {
+	struct spi_device *client;
+	struct input_dev *input;
+	u8 msg_counter;
+};
+
+static int ec_input_read(struct ariel_pwrbutton *priv,
+			 struct ec_input_response *response)
+{
+	u8 read_request[] = { 0x00, 0x5a, 0xa5, 0x00, 0x00 };
+	struct spi_device *spi = priv->client;
+	struct spi_transfer t = {
+		.tx_buf = read_request,
+		.rx_buf = response,
+		.len = sizeof(read_request),
+	};
+
+	compiletime_assert(sizeof(read_request) == sizeof(*response),
+			   "SPI xfer request/response size mismatch");
+
+	return spi_sync_transfer(spi, &t, 1);
+}
+
+static irqreturn_t ec_input_interrupt(int irq, void *dev_id)
+{
+	struct ariel_pwrbutton *priv = dev_id;
+	struct spi_device *spi = priv->client;
+	struct ec_input_response response;
+	int error;
+	int i;
+
+	error = ec_input_read(priv, &response);
+	if (error < 0) {
+		dev_err(&spi->dev, "EC read failed: %d\n", error);
+		goto out;
+	}
+
+	if (priv->msg_counter == RESP_COUNTER(response)) {
+		dev_warn(&spi->dev, "No new data to read?\n");
+		goto out;
+	}
+
+	priv->msg_counter = RESP_COUNTER(response);
+
+	if (RESP_TYPE(response) != 0x3 && RESP_TYPE(response) != 0xc) {
+		dev_dbg(&spi->dev, "Ignoring message that's not kbd data\n");
+		goto out;
+	}
+
+	for (i = 0; i < RESP_SIZE(response); i++) {
+		switch (response.data[i]) {
+		case 0x74:
+			input_report_key(priv->input, KEY_POWER, 1);
+			input_sync(priv->input);
+			break;
+		case 0xf4:
+			input_report_key(priv->input, KEY_POWER, 0);
+			input_sync(priv->input);
+			break;
+		default:
+			dev_dbg(&spi->dev, "Unknown scan code: %02x\n",
+				response.data[i]);
+		}
+	}
+
+out:
+	return IRQ_HANDLED;
+}
+
+static int ariel_pwrbutton_probe(struct spi_device *spi)
+{
+	struct ec_input_response response;
+	struct ariel_pwrbutton *priv;
+	int error;
+
+	if (!spi->irq) {
+		dev_err(&spi->dev, "Missing IRQ.\n");
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = spi;
+	spi_set_drvdata(spi, priv);
+
+	priv->input = devm_input_allocate_device(&spi->dev);
+	if (!priv->input)
+		return -ENOMEM;
+	priv->input->name = "Power Button";
+	priv->input->dev.parent = &spi->dev;
+	input_set_capability(priv->input, EV_KEY, KEY_POWER);
+	error = input_register_device(priv->input);
+	if (error) {
+		dev_err(&spi->dev, "error registering input device: %d\n", error);
+		return error;
+	}
+
+	error = ec_input_read(priv, &response);
+	if (error < 0) {
+		dev_err(&spi->dev, "EC read failed: %d\n", error);
+		return error;
+	}
+	priv->msg_counter = RESP_COUNTER(response);
+
+	error = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
+					  ec_input_interrupt,
+					  IRQF_ONESHOT,
+					  "Ariel EC Input", priv);
+
+	if (error) {
+		dev_err(&spi->dev, "Failed to request IRQ %d: %d\n",
+			spi->irq, error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id ariel_pwrbutton_of_match[] = {
+	{ .compatible = "dell,wyse-ariel-ec-input" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ariel_pwrbutton_of_match);
+
+static const struct spi_device_id ariel_pwrbutton_id_table[] = {
+	{ "wyse-ariel-ec-input", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, ariel_pwrbutton_id_table);
+
+static struct spi_driver ariel_pwrbutton_driver = {
+	.driver = {
+		.name = "dell-wyse-ariel-ec-input",
+		.of_match_table = ariel_pwrbutton_of_match,
+	},
+	.probe = ariel_pwrbutton_probe,
+};
+module_spi_driver(ariel_pwrbutton_driver);
+
+MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
+MODULE_DESCRIPTION("Dell Wyse 3020 Power Button Input Driver");
+MODULE_LICENSE("Dual BSD/GPL");