Date:	Tue, 29 Sep 2015 18:16:47 +0200
From:	Noralf Trønnes <noralf@...nnes.org>
To:	dmitry.torokhov@...il.com
Cc:	xobs@...agi.com, mark@...maker.com, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Noralf Trønnes <noralf@...nnes.org>
Subject: [PATCH] Input: Add support for FocalTech FT6236 touchscreen controller

This adds support for the FT6x06 and the FT6x36 family of
capacitive touch panel controllers, in particular the FT6236.

Signed-off-by: Noralf Trønnes <noralf@...nnes.org>
---

The driver is based on:
https://github.com/adafruit/adafruit-raspberrypi-linux/blob/rpi-3.18.y/drivers/input/touchscreen/ft6x06_ts.c

 .../input/touchscreen/focaltech-ft6236.txt         |  35 +++
 .../devicetree/bindings/vendor-prefixes.txt        |   1 +
 drivers/input/touchscreen/Kconfig                  |  14 +
 drivers/input/touchscreen/Makefile                 |   1 +
 drivers/input/touchscreen/ft6236.c                 | 322 +++++++++++++++++++++
 5 files changed, 373 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/focaltech-ft6236.txt
 create mode 100644 drivers/input/touchscreen/ft6236.c

diff --git a/Documentation/devicetree/bindings/input/touchscreen/focaltech-ft6236.txt b/Documentation/devicetree/bindings/input/touchscreen/focaltech-ft6236.txt
new file mode 100644
index 0000000..777521d
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/focaltech-ft6236.txt
@@ -0,0 +1,35 @@
+* FocalTech FT6236 I2C touchscreen controller
+
+Required properties:
+ - compatible		  : "focaltech,ft6236"
+ - reg			  : I2C slave address of the chip (0x38)
+ - interrupt-parent	  : a phandle pointing to the interrupt controller
+			    serving the interrupt for this chip
+ - interrupts		  : interrupt specification for the touch controller
+			    interrupt
+ - reset-gpios		  : GPIO specification for the RSTN input
+ - touchscreen-size-x	  : horizontal resolution of touchscreen (in pixels)
+ - touchscreen-size-y	  : vertical resolution of touchscreen (in pixels)
+
+Optional properties:
+ - touchscreen-fuzz-x	  : horizontal noise value of the absolute input
+			    device (in pixels)
+ - touchscreen-fuzz-y	  : vertical noise value of the absolute input
+			    device (in pixels)
+ - touchscreen-inverted-x : X axis is inverted (boolean)
+ - touchscreen-inverted-y : Y axis is inverted (boolean)
+ - touchscreen-swapped-x-y: X and Y axis are swapped (boolean)
+			    Swapping is done after inverting the axis
+
+Example:
+
+	ft6x06@38 {
+		compatible = "focaltech,ft6236";
+		reg = <0x38>;
+		interrupt-parent = <&gpio>;
+		interrupts = <23 2>;
+		touchscreen-size-x = <320>;
+		touchscreen-size-y = <480>;
+		touchscreen-inverted-x;
+		touchscreen-swapped-x-y;
+	};
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index 8033919..08490ef 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -76,6 +76,7 @@ everspin	Everspin Technologies, Inc.
 excito	Excito
 fcs	Fairchild Semiconductor
 firefly	Firefly
+focaltech	FocalTech Systems Co.,Ltd
 fsl	Freescale Semiconductor
 GEFanuc	GE Fanuc Intelligent Platforms Embedded Systems, Inc.
 gef	GE Fanuc Intelligent Platforms Embedded Systems, Inc.
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index d7e74a1..7982b87 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -295,6 +295,20 @@ config TOUCHSCREEN_EGALAX
 	  To compile this driver as a module, choose M here: the
 	  module will be called egalax_ts.

+config TOUCHSCREEN_FT6236
+	tristate "FT6236 I2C touchscreen"
+	depends on I2C
+	depends on GPIOLIB
+	help
+	  Say Y here to enable support for the I2C connected FT6x06 and
+	  FT6x36 family of capacitive touchscreen drivers.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ft6236.
+
+
 config TOUCHSCREEN_FUJITSU
 	tristate "Fujitsu serial touchscreen"
 	select SERIO
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index a1be09f..c867f82 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_TOUCHSCREEN_EETI)		+= eeti_ts.o
 obj-$(CONFIG_TOUCHSCREEN_ELAN)		+= elants_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_ELO)		+= elo.o
 obj-$(CONFIG_TOUCHSCREEN_EGALAX)	+= egalax_ts.o
+obj-$(CONFIG_TOUCHSCREEN_FT6236)	+= ft6236.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
diff --git a/drivers/input/touchscreen/ft6236.c b/drivers/input/touchscreen/ft6236.c
new file mode 100644
index 0000000..7531a4c
--- /dev/null
+++ b/drivers/input/touchscreen/ft6236.c
@@ -0,0 +1,322 @@
+/*
+ * FocalTech FT6236 TouchScreen driver.
+ *
+ * Copyright (c) 2010  Focal tech Ltd.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/property.h>
+
+#define FT6236_MAX_TOUCH_POINTS		2
+
+#define FT6236_REG_TH_GROUP		0x80
+#define FT6236_REG_PERIODACTIVE		0x88
+#define FT6236_REG_LIB_VER_H		0xa1
+#define FT6236_REG_LIB_VER_L		0xa2
+#define FT6236_REG_CIPHER		0xa3
+#define FT6236_REG_FIRMID		0xa6
+#define FT6236_REG_FOCALTECH_ID		0xa8
+#define FT6236_REG_RELEASE_CODE_ID	0xaf
+
+#define FT6236_EVENT_PRESS_DOWN		0
+#define FT6236_EVENT_LIFT_UP		1
+#define FT6236_EVENT_CONTACT		2
+#define FT6236_EVENT_NO_EVENT		3
+
+struct ft6236_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+	struct gpio_desc *reset_gpio;
+	u32 max_x;
+	u32 max_y;
+	bool invert_x;
+	bool invert_y;
+	bool swap_xy;
+};
+
+/*
+ * This struct is a touchpoint as stored in hardware.  Note that the id,
+ * as well as the event, are stored in the upper nybble of the hi byte.
+ */
+struct ft6236_touchpoint {
+	union {
+		u8 xhi;
+		u8 event;
+	};
+	u8 xlo;
+	union {
+		u8 yhi;
+		u8 id;
+	};
+	u8 ylo;
+	u8 weight;
+	u8 misc;
+} __packed;
+
+/* This packet represents the register map as read from offset 0 */
+struct ft6236_packet {
+	u8 dev_mode;
+	u8 gest_id;
+	u8 touches;
+	struct ft6236_touchpoint points[FT6236_MAX_TOUCH_POINTS];
+} __packed;
+
+static int ft6236_read(struct i2c_client *client, u8 reg, u8 len, void *data)
+{
+	int ret;
+
+	ret = i2c_smbus_read_i2c_block_data(client, reg, len, data);
+	if (ret < 0)
+		return ret;
+	if (ret != len)
+		return -EIO;
+	return 0;
+}
+
+static irqreturn_t ft6236_interrupt(int irq, void *dev_id)
+{
+	struct ft6236_data *ft6236 = dev_id;
+	struct device *dev = &ft6236->client->dev;
+	struct input_dev *input = ft6236->input;
+	struct ft6236_packet buf;
+	u8 touches;
+	int i, ret;
+
+	ret = ft6236_read(ft6236->client, 0, sizeof(buf), &buf);
+	if (ret) {
+		dev_err(dev, "read touchdata failed %d\n", ret);
+		return IRQ_HANDLED;
+	}
+
+	touches = buf.touches & 0xf;
+	if (touches > FT6236_MAX_TOUCH_POINTS) {
+		dev_dbg(dev,
+			"%d touch points reported, only %d are supported\n",
+			touches, FT6236_MAX_TOUCH_POINTS);
+		touches = FT6236_MAX_TOUCH_POINTS;
+	}
+
+	for (i = 0; i < touches; i++) {
+		u16 x = ((buf.points[i].xhi & 0xf) << 8) | buf.points[i].xlo;
+		u16 y = ((buf.points[i].yhi & 0xf) << 8) | buf.points[i].ylo;
+		u8 event = buf.points[i].event >> 6;
+		u8 id = buf.points[i].id >> 4;
+		bool act = (event == FT6236_EVENT_PRESS_DOWN ||
+			    event == FT6236_EVENT_CONTACT);
+
+		input_mt_slot(input, id);
+		input_mt_report_slot_state(input, MT_TOOL_FINGER, act);
+		if (!act)
+			continue;
+
+		if (ft6236->invert_x)
+			x = ft6236->max_x - x;
+
+		if (ft6236->invert_y)
+			y = ft6236->max_y - y;
+
+		if (ft6236->swap_xy) {
+			input_report_abs(input, ABS_MT_POSITION_X, y);
+			input_report_abs(input, ABS_MT_POSITION_Y, x);
+		} else {
+			input_report_abs(input, ABS_MT_POSITION_X, x);
+			input_report_abs(input, ABS_MT_POSITION_Y, y);
+		}
+	}
+
+	input_mt_sync_frame(input);
+	input_sync(input);
+
+	return IRQ_HANDLED;
+}
+
+static u8 ft6236_debug_read_byte(struct ft6236_data *ft6236, u8 reg)
+{
+	struct i2c_client *client = ft6236->client;
+	u8 val = 0;
+	int ret;
+
+	ret = ft6236_read(client, reg, 1, &val);
+	if (ret)
+		dev_dbg(&client->dev, "error reading register 0x%02x\n", reg);
+	return val;
+}
+
+static void ft6236_debug_info(struct ft6236_data *ft6236)
+{
+	struct device *dev = &ft6236->client->dev;
+
+	dev_dbg(dev, "Touch threshold is %d\n",
+		ft6236_debug_read_byte(ft6236, FT6236_REG_TH_GROUP) * 4);
+	dev_dbg(dev, "Report rate is %dHz\n",
+		ft6236_debug_read_byte(ft6236, FT6236_REG_PERIODACTIVE) * 10);
+	dev_dbg(dev, "Firmware library version 0x%02x%02x\n",
+		ft6236_debug_read_byte(ft6236, FT6236_REG_LIB_VER_H),
+		ft6236_debug_read_byte(ft6236, FT6236_REG_LIB_VER_L));
+	dev_dbg(dev, "Firmware version 0x%02x\n",
+		ft6236_debug_read_byte(ft6236, FT6236_REG_FIRMID));
+	dev_dbg(dev, "Chip vendor ID 0x%02x\n",
+		ft6236_debug_read_byte(ft6236, FT6236_REG_CIPHER));
+	dev_dbg(dev, "CTPM vendor ID 0x%02x\n",
+		ft6236_debug_read_byte(ft6236, FT6236_REG_FOCALTECH_ID));
+	dev_dbg(dev, "Release code version 0x%02x\n",
+		ft6236_debug_read_byte(ft6236, FT6236_REG_RELEASE_CODE_ID));
+}
+
+static void ft6236_reset(struct ft6236_data *ft6236)
+{
+	if (!ft6236->reset_gpio)
+		return;
+
+	gpiod_set_value_cansleep(ft6236->reset_gpio, 0);
+	usleep_range(5000, 20000);
+	gpiod_set_value_cansleep(ft6236->reset_gpio, 1);
+	msleep(300);
+}
+
+static int ft6236_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct ft6236_data *ft6236;
+	struct input_dev *input;
+	u32 fuzz_x = 0, fuzz_y = 0;
+	u8 val;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	if (!client->irq) {
+		dev_err(dev, "irq is missing\n");
+		return -EINVAL;
+	}
+
+	ft6236 = devm_kzalloc(dev, sizeof(*ft6236), GFP_KERNEL);
+	if (!ft6236)
+		return -ENOMEM;
+
+	ft6236->client = client;
+	ft6236->reset_gpio = devm_gpiod_get_optional(dev, "reset",
+						     GPIOD_OUT_HIGH);
+	if (IS_ERR(ft6236->reset_gpio)) {
+		ret = PTR_ERR(ft6236->reset_gpio);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "error getting reset gpio\n");
+		return ret;
+	}
+
+	ft6236_reset(ft6236);
+
+	/* verify that the controller is present */
+	ret = ft6236_read(client, 0x00, 1, &val);
+	if (ret) {
+		dev_err(dev, "failed to read from controller\n");
+		return ret;
+	}
+
+	ft6236_debug_info(ft6236);
+
+	input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	ft6236->input = input;
+	input->name = client->name;
+	input->id.bustype = BUS_I2C;
+
+	if (device_property_read_u32(dev, "touchscreen-size-x",
+				     &ft6236->max_x) ||
+	    device_property_read_u32(dev, "touchscreen-size-y",
+				     &ft6236->max_y)) {
+		dev_err(dev, "touchscreen-size-x and/or -y missing\n");
+		return -EINVAL;
+	}
+
+	device_property_read_u32(dev, "touchscreen-fuzz-x", &fuzz_x);
+	device_property_read_u32(dev, "touchscreen-fuzz-y", &fuzz_y);
+	ft6236->invert_x = device_property_read_bool(dev,
+						     "touchscreen-inverted-x");
+	ft6236->invert_y = device_property_read_bool(dev,
+						     "touchscreen-inverted-y");
+	ft6236->swap_xy = device_property_read_bool(dev,
+						    "touchscreen-swapped-x-y");
+
+	if (ft6236->swap_xy) {
+		input_set_abs_params(input, ABS_MT_POSITION_X, 0,
+				     ft6236->max_y, fuzz_y, 0);
+		input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
+				     ft6236->max_x, fuzz_x, 0);
+	} else {
+		input_set_abs_params(input, ABS_MT_POSITION_X, 0,
+				     ft6236->max_x, fuzz_x, 0);
+		input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
+				     ft6236->max_y, fuzz_y, 0);
+	}
+
+	ret = input_mt_init_slots(input, FT6236_MAX_TOUCH_POINTS,
+				  INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (ret)
+		return ret;
+
+	ret = devm_request_threaded_irq(dev, client->irq, NULL,
+					ft6236_interrupt, IRQF_ONESHOT,
+					client->name, ft6236);
+	if (ret < 0) {
+		dev_err(dev, "request irq failed\n");
+		return ret;
+	}
+
+	ret = input_register_device(input);
+	if (ret) {
+		dev_err(dev, "failed to register input device\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id ft6236_of_match[] = {
+	{ .compatible = "focaltech,ft6236", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ft6236_of_match);
+
+static const struct i2c_device_id ft6236_id[] = {
+	{ "ft6236", },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ft6236_id);
+
+static struct i2c_driver ft6236_driver = {
+	.driver = {
+		.name = "ft6236",
+		.owner = THIS_MODULE,
+		.of_match_table = ft6236_of_match,
+	},
+	.probe = ft6236_probe,
+	.id_table = ft6236_id,
+};
+
+module_i2c_driver(ft6236_driver);
+
+MODULE_AUTHOR("Sean Cross <xobs@...agi.com>");
+MODULE_AUTHOR("Noralf Trønnes <noralf@...nnes.org>");
+MODULE_DESCRIPTION("FocalTech FT6236 TouchScreen driver");
+MODULE_LICENSE("GPL");
--
2.2.2

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