Input: add driver for power button on Dell Wyse 3020

@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/ariel-pwrbutton.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Dell Wyse 3020 a.k.a. "Ariel" Power Button
+
+maintainers:
+  - Lubomir Rintel <lkundrak@v3.sk>
+
+description: |
+  The ENE Embedded Controller on the Ariel board has an interface to the
+  SPI bus that is capable of sending keyboard and mouse data. A single
+  power button is attached to it. This binding describes this
+  configuration.
+
+allOf:
+  - $ref: input.yaml#
+
+properties:
+  compatible:
+    items:
+      - const: dell,wyse-ariel-ec-input
+      - const: ene,kb3930-input
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        power-button@0 {
+            compatible = "dell,wyse-ariel-ec-input", "ene,kb3930-input";
+            reg = <0>;
+            interrupt-parent = <&gpio>;
+            interrupts = <60 IRQ_TYPE_EDGE_RISING>;
+            spi-max-frequency = <33000000>;
+        };
+    };

@@ -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

@@ -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

@@ -0,0 +1,168 @@
+// 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/module.h>
+#include <linux/spi/spi.h>
+#include <linux/interrupt.h>
+#include <linux/input.h>
+
+struct ec_input_response {
+	u8 reserved;
+	u8 msg_counter:2;
+	u8 count:2;
+	u8 type:4;
+	u8 data[3];
+} __packed;
+
+struct ariel_pwrbutton {
+	struct spi_device *client;
+	struct input_dev *input;
+	u8 msg_counter:2;
+};
+
+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 i;
+
+	if (ec_input_read(priv, &response) < 0) {
+		dev_err(&spi->dev, "EC read failed.\n");
+		return IRQ_HANDLED;
+	}
+
+	if (priv->msg_counter == response.msg_counter) {
+		dev_warn(&spi->dev, "No new data to read?\n");
+		return IRQ_HANDLED;
+	}
+
+	priv->msg_counter = response.msg_counter;
+
+	if (response.type != 0x03 && response.type != 0x0c) {
+		dev_dbg(&spi->dev, "Ignoring message that's not kbd data\n");
+		return IRQ_HANDLED;
+	}
+
+	if (response.count > ARRAY_SIZE(response.data)) {
+		response.count = ARRAY_SIZE(response.data);
+		dev_warn(&spi->dev, "Truncating a long response\n");
+	}
+
+	for (i = 0; i < response.count; i++) {
+		dev_err(&spi->dev, "scan code %02x\n", response.data[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]);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int ariel_pwrbutton_probe(struct spi_device *spi)
+{
+	struct ec_input_response response;
+	struct ariel_pwrbutton *priv;
+	int ret;
+
+	if (!spi->irq) {
+		dev_err(&spi->dev, "Missing IRQ.\n");
+		return -ENXIO;
+	}
+
+	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);
+	ret = input_register_device(priv->input);
+	if (ret) {
+		dev_err(&spi->dev, "error registering input device: %d\n", ret);
+		return ret;
+	}
+
+	ret = ec_input_read(priv, &response);
+	if (ret < 0) {
+		dev_err(&spi->dev, "EC read failed: %d\n", ret);
+		return ret;
+	}
+	priv->msg_counter = response.msg_counter;
+
+	ret = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
+					ec_input_interrupt,
+					IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+					"Ariel EC Input", priv);
+
+	if (ret) {
+		dev_err(&spi->dev, "Failed to request IRQ %d: %d\n",
+			spi->irq, ret);
+		return ret;
+	}
+
+	dev_info(&spi->dev, "Dell Wyse 3020 Power Button\n");
+	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");