Input: add new driver for the Surface 3

This is a basic driver for the Surface 3. I am not so sure it will work
with any firmwares as most values are encoded, but given that I only have
access to my current device with its firmware and I don't have the
datasheet, it should be OK for now.

The Surface Pen is not supported (if it is supposed to be). I'll work on
this when I get one.
Tested-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/Kconfig

@@ -1085,6 +1085,19 @@ config TOUCHSCREEN_SUR40
 	  To compile this driver as a module, choose M here: the
 	  module will be called sur40.
 
+config TOUCHSCREEN_SURFACE3_SPI
+	tristate "Ntrig/Microsoft Surface 3 SPI touchscreen"
+	depends on SPI
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say Y here if you have the Ntrig/Microsoft SPI touchscreen
+	  controller chip as found on the Surface 3 in your system.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called surface3_spi.
+
 config TOUCHSCREEN_SX8654
 	tristate "Semtech SX8654 touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile

@@ -66,6 +66,7 @@ obj-$(CONFIG_TOUCHSCREEN_ST1232)	+= st1232.o
 obj-$(CONFIG_TOUCHSCREEN_STMPE)		+= stmpe-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUN4I)		+= sun4i-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUR40)		+= sur40.o
+obj-$(CONFIG_TOUCHSCREEN_SURFACE3_SPI)	+= surface3_spi.o
 obj-$(CONFIG_TOUCHSCREEN_TI_AM335X_TSC)	+= ti_am335x_tsc.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHIT213)	+= touchit213.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHRIGHT)	+= touchright.o

drivers/input/touchscreen/surface3_spi.c

+/*
+ *  Driver for Ntrig/Microsoft Touchscreens over SPI
+ *
+ *  Copyright (c) 2016 Red Hat Inc.
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; version 2 of the License.
+ */
+
+#include <linux/kernel.h>
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/acpi.h>
+
+#include <asm/unaligned.h>
+
+#define SURFACE3_PACKET_SIZE	264
+
+struct surface3_ts_data {
+	struct spi_device *spi;
+	struct gpio_desc *gpiod_rst[2];
+	struct input_dev *input_dev;
+
+	u8 rd_buf[SURFACE3_PACKET_SIZE]		____cacheline_aligned;
+};
+
+struct surface3_ts_data_finger {
+	u8 status;
+	__le16 tracking_id;
+	__le16 x;
+	__le16 cx;
+	__le16 y;
+	__le16 cy;
+	__le16 width;
+	__le16 height;
+	u32 padding;
+} __packed;
+
+static int surface3_spi_read(struct surface3_ts_data *ts_data)
+{
+	struct spi_device *spi = ts_data->spi;
+
+	memset(ts_data->rd_buf, 0, sizeof(ts_data->rd_buf));
+	return spi_read(spi, ts_data->rd_buf, sizeof(ts_data->rd_buf));
+}
+
+static void surface3_spi_report_touch(struct surface3_ts_data *ts_data,
+				   struct surface3_ts_data_finger *finger)
+{
+	int st = finger->status & 0x01;
+	int slot;
+
+	slot = input_mt_get_slot_by_key(ts_data->input_dev,
+				get_unaligned_le16(&finger->tracking_id));
+	if (slot < 0)
+		return;
+
+	input_mt_slot(ts_data->input_dev, slot);
+	input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, st);
+	if (st) {
+		input_report_abs(ts_data->input_dev,
+				 ABS_MT_POSITION_X,
+				 get_unaligned_le16(&finger->x));
+		input_report_abs(ts_data->input_dev,
+				 ABS_MT_POSITION_Y,
+				 get_unaligned_le16(&finger->y));
+		input_report_abs(ts_data->input_dev,
+				 ABS_MT_WIDTH_MAJOR,
+				 get_unaligned_le16(&finger->width));
+		input_report_abs(ts_data->input_dev,
+				 ABS_MT_WIDTH_MINOR,
+				 get_unaligned_le16(&finger->height));
+	}
+}
+
+static void surface3_spi_process(struct surface3_ts_data *ts_data)
+{
+	const char header[] = {0xff, 0xff, 0xff, 0xff, 0xa5, 0x5a, 0xe7, 0x7e,
+			       0x01, 0xd2, 0x00, 0x80, 0x01, 0x03, 0x03};
+	u8 *data = ts_data->rd_buf;
+	u16 timestamp;
+	unsigned int i;
+
+	if (memcmp(header, data, sizeof(header)))
+		dev_err(&ts_data->spi->dev,
+			"%s header error: %*ph, ignoring...\n",
+			__func__, (int)sizeof(header), data);
+
+	timestamp = get_unaligned_le16(&data[15]);
+
+	for (i = 0; i < 13; i++) {
+		struct surface3_ts_data_finger *finger;
+
+		finger = (struct surface3_ts_data_finger *)&data[17 +
+				i * sizeof(struct surface3_ts_data_finger)];
+
+		/*
+		 * When bit 5 of status is 1, it marks the end of the report:
+		 * - touch present: 0xe7
+		 * - touch released: 0xe4
+		 * - nothing valuable: 0xff
+		 */
+		if (finger->status & 0x10)
+			break;
+
+		surface3_spi_report_touch(ts_data, finger);
+	}
+
+	input_mt_sync_frame(ts_data->input_dev);
+	input_sync(ts_data->input_dev);
+}
+
+static irqreturn_t surface3_spi_irq_handler(int irq, void *dev_id)
+{
+	struct surface3_ts_data *data = dev_id;
+
+	if (surface3_spi_read(data))
+		return IRQ_HANDLED;
+
+	dev_dbg(&data->spi->dev, "%s received -> %*ph\n",
+		__func__, SURFACE3_PACKET_SIZE, data->rd_buf);
+	surface3_spi_process(data);
+
+	return IRQ_HANDLED;
+}
+
+static void surface3_spi_power(struct surface3_ts_data *data, bool on)
+{
+	gpiod_set_value(data->gpiod_rst[0], on);
+	gpiod_set_value(data->gpiod_rst[1], on);
+	/* let the device settle a little */
+	msleep(20);
+}
+
+/**
+ * surface3_spi_get_gpio_config - Get GPIO config from ACPI/DT
+ *
+ * @ts: surface3_spi_ts_data pointer
+ */
+static int surface3_spi_get_gpio_config(struct surface3_ts_data *data)
+{
+	int error;
+	struct device *dev;
+	struct gpio_desc *gpiod;
+	int i;
+
+	dev = &data->spi->dev;
+
+	/* Get the reset lines GPIO pin number */
+	for (i = 0; i < 2; i++) {
+		gpiod = devm_gpiod_get_index(dev, NULL, i, GPIOD_OUT_LOW);
+		if (IS_ERR(gpiod)) {
+			error = PTR_ERR(gpiod);
+			if (error != -EPROBE_DEFER)
+				dev_err(dev,
+					"Failed to get power GPIO %d: %d\n",
+					i,
+					error);
+			return error;
+		}
+
+		data->gpiod_rst[i] = gpiod;
+	}
+
+	return 0;
+}
+
+static int surface3_spi_create_input(struct surface3_ts_data *data)
+{
+	struct input_dev *input;
+	int error;
+
+	input = devm_input_allocate_device(&data->spi->dev);
+	if (!input)
+		return -ENOMEM;
+
+	data->input_dev = input;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0, 9600, 0, 0);
+	input_abs_set_res(input, ABS_MT_POSITION_X, 40);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, 7200, 0, 0);
+	input_abs_set_res(input, ABS_MT_POSITION_Y, 48);
+	input_set_abs_params(input, ABS_MT_WIDTH_MAJOR, 0, 1024, 0, 0);
+	input_set_abs_params(input, ABS_MT_WIDTH_MINOR, 0, 1024, 0, 0);
+	input_mt_init_slots(input, 10, INPUT_MT_DIRECT);
+
+	input->name = "Surface3 SPI Capacitive TouchScreen";
+	input->phys = "input/ts";
+	input->id.bustype = BUS_SPI;
+	input->id.vendor = 0x045e;	/* Microsoft */
+	input->id.product = 0x0000;
+	input->id.version = 0x0000;
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(&data->spi->dev,
+			"Failed to register input device: %d", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int surface3_spi_probe(struct spi_device *spi)
+{
+	struct surface3_ts_data *data;
+	int error;
+
+	/* Set up SPI*/
+	spi->bits_per_word = 8;
+	spi->mode = SPI_MODE_0;
+	error = spi_setup(spi);
+	if (error)
+		return error;
+
+	data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->spi = spi;
+	spi_set_drvdata(spi, data);
+
+	error = surface3_spi_get_gpio_config(data);
+	if (error)
+		return error;
+
+	surface3_spi_power(data, true);
+	surface3_spi_power(data, false);
+	surface3_spi_power(data, true);
+
+	error = surface3_spi_create_input(data);
+	if (error)
+		return error;
+
+	error = devm_request_threaded_irq(&spi->dev, spi->irq,
+					  NULL, surface3_spi_irq_handler,
+					  IRQF_ONESHOT,
+					  "Surface3-irq", data);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static int __maybe_unused surface3_spi_suspend(struct device *dev)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct surface3_ts_data *data = spi_get_drvdata(spi);
+
+	disable_irq(data->spi->irq);
+
+	surface3_spi_power(data, false);
+
+	return 0;
+}
+
+static int __maybe_unused surface3_spi_resume(struct device *dev)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct surface3_ts_data *data = spi_get_drvdata(spi);
+
+	surface3_spi_power(data, true);
+
+	enable_irq(data->spi->irq);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(surface3_spi_pm_ops,
+			 surface3_spi_suspend,
+			 surface3_spi_resume);
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id surface3_spi_acpi_match[] = {
+	{ "MSHW0037", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, surface3_spi_acpi_match);
+#endif
+
+static struct spi_driver surface3_spi_driver = {
+	.driver = {
+		.name	= "Surface3-spi",
+		.acpi_match_table = ACPI_PTR(surface3_spi_acpi_match),
+		.pm = &surface3_spi_pm_ops,
+	},
+	.probe = surface3_spi_probe,
+};
+
+module_spi_driver(surface3_spi_driver);
+
+MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
+MODULE_DESCRIPTION("Surface 3 SPI touchscreen driver");
+MODULE_LICENSE("GPL v2");