Add I2C attached EETI EXC3000 multi touch driver

Documentation/devicetree/bindings/input/touchscreen/exc3000.txt

@@ -0,0 +1,27 @@
+* EETI EXC3000 Multiple Touch Controller
+
+Required properties:
+- compatible: must be "eeti,exc3000"
+- reg: i2c slave address
+- interrupt-parent: the phandle for the interrupt controller
+- interrupts: touch controller interrupt
+- touchscreen-size-x: See touchscreen.txt
+- touchscreen-size-y: See touchscreen.txt
+
+Optional properties:
+- touchscreen-inverted-x: See touchscreen.txt
+- touchscreen-inverted-y: See touchscreen.txt
+- touchscreen-swapped-x-y: See touchscreen.txt
+
+Example:
+
+	touchscreen@2a {
+		compatible = "eeti,exc3000";
+		reg = <0x2a>;
+		interrupt-parent = <&gpio1>;
+		interrupts = <9 IRQ_TYPE_LEVEL_LOW>;
+		touchscreen-size-x = <4096>;
+		touchscreen-size-y = <4096>;
+		touchscreen-inverted-x;
+		touchscreen-swapped-x-y;
+	};

arch/arm/boot/dts/overlays/Makefile

@@ -26,6 +26,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
 	dwc2.dtbo \
 	enc28j60.dtbo \
 	enc28j60-spi2.dtbo \
+	exc3000.dtbo \
 	fe-pi-audio.dtbo \
 	goodix.dtbo \
 	googlevoicehat-soundcard.dtbo \

arch/arm/boot/dts/overlays/README

@@ -468,6 +468,18 @@ Params: int_pin                 GPIO used for INT (default 39)
         speed                   SPI bus speed (default 12000000)
 
 
+Name:   exc3000
+Info:   Enables I2C connected EETI EXC3000 multiple touch controller using
+        GPIO 4 (pin 7 on GPIO header) for interrupt.
+Load:   dtoverlay=exc3000,<param>=<val>
+Params: interrupt               GPIO used for interrupt (default 4)
+        sizex                   Touchscreen size x (default 4096)
+        sizey                   Touchscreen size y (default 4096)
+        invx                    Touchscreen inverted x axis
+        invy                    Touchscreen inverted y axis
+        swapxy                  Touchscreen swapped x y axis
+
+
 Name:   fe-pi-audio
 Info:   Configures the Fe-Pi Audio Sound Card
 Load:   dtoverlay=fe-pi-audio

arch/arm/boot/dts/overlays/exc3000-overlay.dts

@@ -0,0 +1,48 @@
+// Device tree overlay for I2C connected EETI EXC3000 multiple touch controller
+/dts-v1/;
+/plugin/;
+
+/ {
+	compatible = "brcm,bcm2708";
+
+	fragment@0 {
+		target = <&gpio>;
+		__overlay__ {
+			exc3000_pins: exc3000_pins {
+				brcm,pins = <4>; // interrupt
+				brcm,function = <0>; // in
+				brcm,pull = <2>; // pull-up
+			};
+		};
+	};
+
+	fragment@1 {
+		target = <&i2c1>;
+		__overlay__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			exc3000: exc3000@2a {
+				compatible = "eeti,exc3000";
+				reg = <0x2a>;
+				pinctrl-names = "default";
+				pinctrl-0 = <&exc3000_pins>;
+				interrupt-parent = <&gpio>;
+				interrupts = <4 8>; // active low level-sensitive
+				touchscreen-size-x = <4096>;
+				touchscreen-size-y = <4096>;
+			};
+		};
+	};
+
+	__overrides__ {
+		interrupt = <&exc3000_pins>,"brcm,pins:0",
+			<&exc3000>,"interrupts:0";
+		sizex = <&exc3000>,"touchscreen-size-x:0";
+		sizey = <&exc3000>,"touchscreen-size-y:0";
+		invx = <&exc3000>,"touchscreen-inverted-x?";
+		invy = <&exc3000>,"touchscreen-inverted-y?";
+		swapxy = <&exc3000>,"touchscreen-swapped-x-y?";
+	};
+};

arch/arm/configs/bcm2709_defconfig

@@ -573,6 +573,7 @@ CONFIG_JOYSTICK_RPISENSE=m
 CONFIG_INPUT_TOUCHSCREEN=y
 CONFIG_TOUCHSCREEN_ADS7846=m
 CONFIG_TOUCHSCREEN_EGALAX=m
+CONFIG_TOUCHSCREEN_EXC3000=m
 CONFIG_TOUCHSCREEN_GOODIX=m
 CONFIG_TOUCHSCREEN_EDT_FT5X06=m
 CONFIG_TOUCHSCREEN_RPI_FT5406=m

arch/arm/configs/bcmrpi_defconfig

@@ -569,6 +569,7 @@ CONFIG_JOYSTICK_RPISENSE=m
 CONFIG_INPUT_TOUCHSCREEN=y
 CONFIG_TOUCHSCREEN_ADS7846=m
 CONFIG_TOUCHSCREEN_EGALAX=m
+CONFIG_TOUCHSCREEN_EXC3000=m
 CONFIG_TOUCHSCREEN_GOODIX=m
 CONFIG_TOUCHSCREEN_EDT_FT5X06=m
 CONFIG_TOUCHSCREEN_RPI_FT5406=m

drivers/input/touchscreen/Kconfig

@@ -314,6 +314,16 @@ config TOUCHSCREEN_EGALAX_SERIAL
 	  To compile this driver as a module, choose M here: the
 	  module will be called egalax_ts_serial.
 
+config TOUCHSCREEN_EXC3000
+	tristate "EETI EXC3000 multi-touch panel support"
+	depends on I2C
+	help
+	  Say Y here to enable support for I2C connected EETI
+	  EXC3000 multi-touch panels.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called exc3000.
+
 config TOUCHSCREEN_FUJITSU
 	tristate "Fujitsu serial touchscreen"
 	select SERIO

drivers/input/touchscreen/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_TOUCHSCREEN_ELAN)		+= elants_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_ELO)		+= elo.o
 obj-$(CONFIG_TOUCHSCREEN_EGALAX)	+= egalax_ts.o
 obj-$(CONFIG_TOUCHSCREEN_EGALAX_SERIAL)	+= egalax_ts_serial.o
+obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o

drivers/input/touchscreen/exc3000.c

@@ -0,0 +1,223 @@
+/*
+ * Driver for I2C connected EETI EXC3000 multiple touch controller
+ *
+ * Copyright (C) 2017 Ahmet Inan <inan@distec.de>
+ *
+ * minimal implementation based on egalax_ts.c and egalax_i2c.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/timer.h>
+#include <asm/unaligned.h>
+
+#define EXC3000_NUM_SLOTS		10
+#define EXC3000_SLOTS_PER_FRAME		5
+#define EXC3000_LEN_FRAME		66
+#define EXC3000_LEN_POINT		10
+#define EXC3000_MT_EVENT		6
+#define EXC3000_TIMEOUT_MS		100
+
+struct exc3000_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+	struct touchscreen_properties prop;
+	struct timer_list timer;
+	u8 buf[2 * EXC3000_LEN_FRAME];
+};
+
+static void exc3000_report_slots(struct input_dev *input,
+				 struct touchscreen_properties *prop,
+				 const u8 *buf, int num)
+{
+	for (; num--; buf += EXC3000_LEN_POINT) {
+		if (buf[0] & BIT(0)) {
+			input_mt_slot(input, buf[1]);
+			input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
+			touchscreen_report_pos(input, prop,
+					       get_unaligned_le16(buf + 2),
+					       get_unaligned_le16(buf + 4),
+					       true);
+		}
+	}
+}
+
+static void exc3000_timer(unsigned long d)
+{
+	struct exc3000_data *data = (void *)d;
+
+	input_mt_sync_frame(data->input);
+	input_sync(data->input);
+}
+
+static int exc3000_read_frame(struct i2c_client *client, u8 *buf)
+{
+	int ret;
+
+	ret = i2c_master_send(client, "'", 2);
+	if (ret < 0)
+		return ret;
+
+	if (ret != 2)
+		return -EIO;
+
+	ret = i2c_master_recv(client, buf, EXC3000_LEN_FRAME);
+	if (ret < 0)
+		return ret;
+
+	if (ret != EXC3000_LEN_FRAME)
+		return -EIO;
+
+	if (get_unaligned_le16(buf) != EXC3000_LEN_FRAME ||
+			buf[2] != EXC3000_MT_EVENT)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int exc3000_read_data(struct i2c_client *client,
+			     u8 *buf, int *n_slots)
+{
+	int error;
+
+	error = exc3000_read_frame(client, buf);
+	if (error)
+		return error;
+
+	*n_slots = buf[3];
+	if (!*n_slots || *n_slots > EXC3000_NUM_SLOTS)
+		return -EINVAL;
+
+	if (*n_slots > EXC3000_SLOTS_PER_FRAME) {
+		/* Read 2nd frame to get the rest of the contacts. */
+		error = exc3000_read_frame(client, buf + EXC3000_LEN_FRAME);
+		if (error)
+			return error;
+
+		/* 2nd chunk must have number of contacts set to 0. */
+		if (buf[EXC3000_LEN_FRAME + 3] != 0)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+static irqreturn_t exc3000_interrupt(int irq, void *dev_id)
+{
+	struct exc3000_data *data = dev_id;
+	struct input_dev *input = data->input;
+	u8 *buf = data->buf;
+	int slots, total_slots;
+	int error;
+
+	error = exc3000_read_data(data->client, buf, &total_slots);
+	if (error) {
+		/* Schedule a timer to release "stuck" contacts */
+		mod_timer(&data->timer,
+			  jiffies + msecs_to_jiffies(EXC3000_TIMEOUT_MS));
+		goto out;
+	}
+
+	/*
+	 * We read full state successfully, no contacts will be "stuck".
+	 */
+	del_timer_sync(&data->timer);
+
+	while (total_slots > 0) {
+		slots = min(total_slots, EXC3000_SLOTS_PER_FRAME);
+		exc3000_report_slots(input, &data->prop, buf + 4, slots);
+		total_slots -= slots;
+		buf += EXC3000_LEN_FRAME;
+	}
+
+	input_mt_sync_frame(input);
+	input_sync(input);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static int exc3000_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct exc3000_data *data;
+	struct input_dev *input;
+	int error;
+
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	setup_timer(&data->timer, exc3000_timer, (unsigned long)data);
+
+	input = devm_input_allocate_device(&client->dev);
+	if (!input)
+		return -ENOMEM;
+
+	data->input = input;
+
+	input->name = "EETI EXC3000 Touch Screen";
+	input->id.bustype = BUS_I2C;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0, 4095, 0, 0);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, 4095, 0, 0);
+	touchscreen_parse_properties(input, true, &data->prop);
+
+	error = input_mt_init_slots(input, EXC3000_NUM_SLOTS,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error)
+		return error;
+
+	error = input_register_device(input);
+	if (error)
+		return error;
+
+	error = devm_request_threaded_irq(&client->dev, client->irq,
+					  NULL, exc3000_interrupt, IRQF_ONESHOT,
+					  client->name, data);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static const struct i2c_device_id exc3000_id[] = {
+	{ "exc3000", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, exc3000_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id exc3000_of_match[] = {
+	{ .compatible = "eeti,exc3000" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, exc3000_of_match);
+#endif
+
+static struct i2c_driver exc3000_driver = {
+	.driver = {
+		.name	= "exc3000",
+		.of_match_table = of_match_ptr(exc3000_of_match),
+	},
+	.id_table	= exc3000_id,
+	.probe		= exc3000_probe,
+};
+
+module_i2c_driver(exc3000_driver);
+
+MODULE_AUTHOR("Ahmet Inan <inan@distec.de>");
+MODULE_DESCRIPTION("I2C connected EETI EXC3000 multiple touch controller driver");
+MODULE_LICENSE("GPL v2");