[PATCH] Input: ili251x - add support for Ilitek ILI251x touchscreens

From: Philipp Puschmann
Date: Mon May 07 2018 - 09:28:02 EST

The driver supports at least the ili2511 chipset but may support other
Ilitek chipsets using Ilitek i2c protocol v3.x.

The tested ili2511-based touchscreen delivers garbage for more than 6
fingers while it should support up to 10 fingers. The reason is still
unclear and this remains a FIXME in the driver for now.

The usage of pressure is optional. Touchscreens may deliver constant
and so useless pressure data.

Signed-off-by: Philipp Puschmann <pp@xxxxxxxxx>
---
.../bindings/input/touchscreen/ili251x.txt | 35 ++
drivers/input/touchscreen/Kconfig | 12 +
drivers/input/touchscreen/Makefile | 1 +
drivers/input/touchscreen/ili251x.c | 350 ++++++++++++++++++
4 files changed, 398 insertions(+)
create mode 100644 Documentation/devicetree/bindings/input/touchscreen/ili251x.txt
create mode 100644 drivers/input/touchscreen/ili251x.c

diff --git a/Documentation/devicetree/bindings/input/touchscreen/ili251x.txt b/Documentation/devicetree/bindings/input/touchscreen/ili251x.txt
new file mode 100644
index 000000000000..f21ad93d3bdd
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/ili251x.txt
@@ -0,0 +1,35 @@
+Ilitek ili251x touchscreen driver
+
+This driver uses protocol version 3 and should be compatible with other
+Ilitek touch controllers that use protocol 3.x
+
+Required properties:
+ - compatible: "ili251x"
+ - reg: I2C slave address of the chip (0x41)
+ - interrupt-parent: a phandle pointing to the interrupt controller
+ serving the interrupt for this chip
+ - interrupts: interrupt specification for the touchdetect
+ interrupt
+
+Optional properties:
+ - reset-gpios: GPIO specification for the RESET input
+
+ - pinctrl-names: should be "default"
+ - pinctrl-0: a phandle pointing to the pin settings for the
+ control gpios
+ - max-fingers: the maximum number of fingers to handle
+ - pressure: support pressure data
+ - generic options : See touchscreen.txt
+
+Example:
+
+ ili251x@41 {
+ compatible = "ili251x";
+ reg = <0x41>;
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_touchpanel>;
+ interrupt-parent = <&gpio5>;
+ interrupts = <20 IRQ_TYPE_EDGE_FALLING>;
+ reset-gpios = <&gpio5 18 GPIO_ACTIVE_HIGH>;
+ max-fingers = <6>;
+ };
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 4f15496fec8b..569528834d48 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -380,6 +380,18 @@ config TOUCHSCREEN_ILI210X
To compile this driver as a module, choose M here: the
module will be called ili210x.

+config TOUCHSCREEN_ILI251X
+ tristate "Ilitek ILI251X based touchscreen"
+ depends on I2C
+ help
+ Say Y here if you have a ILI251X based touchscreen
+ controller. This driver supports ILI2511.
+
+ If unsure, say N.
+
+ To compile this driver as a module, choose M here: the
+ module will be called ili251x.
+
config TOUCHSCREEN_IPROC
tristate "IPROC touch panel driver support"
depends on ARCH_BCM_IPROC || COMPILE_TEST
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index dddae7973436..e795b62e5f64 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_TOUCHSCREEN_FUJITSU) += fujitsu_ts.o
obj-$(CONFIG_TOUCHSCREEN_GOODIX) += goodix.o
obj-$(CONFIG_TOUCHSCREEN_HIDEEP) += hideep.o
obj-$(CONFIG_TOUCHSCREEN_ILI210X) += ili210x.o
+obj-$(CONFIG_TOUCHSCREEN_ILI251X) += ili251x.o
obj-$(CONFIG_TOUCHSCREEN_IMX6UL_TSC) += imx6ul_tsc.o
obj-$(CONFIG_TOUCHSCREEN_INEXIO) += inexio.o
obj-$(CONFIG_TOUCHSCREEN_IPROC) += bcm_iproc_tsc.o
diff --git a/drivers/input/touchscreen/ili251x.c b/drivers/input/touchscreen/ili251x.c
new file mode 100644
index 000000000000..203367b59902
--- /dev/null
+++ b/drivers/input/touchscreen/ili251x.c
@@ -0,0 +1,350 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, emlix GmbH. All rights reserved. */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/irq.h>
+
+#define MAX_FINGERS 10
+#define REG_TOUCHDATA 0x10
+#define TOUCHDATA_FINGERS 6
+#define REG_TOUCHDATA2 0x14
+#define TOUCHDATA2_FINGERS 4
+#define REG_PANEL_INFO 0x20
+#define REG_FIRMWARE_VERSION 0x40
+#define REG_PROTO_VERSION 0x42
+#define REG_CALIBRATE 0xcc
+
+struct finger {
+ u8 x_high:6;
+ u8 dummy:1;
+ u8 status:1;
+ u8 x_low;
+ u8 y_high;
+ u8 y_low;
+ u8 pressure;
+} __packed;
+
+struct touchdata {
+ u8 status;
+ struct finger fingers[MAX_FINGERS];
+} __packed;
+
+struct panel_info {
+ u8 x_low;
+ u8 x_high;
+ u8 y_low;
+ u8 y_high;
+ u8 xchannel_num;
+ u8 ychannel_num;
+ u8 max_fingers;
+} __packed;
+
+struct firmware_version {
+ u8 id;
+ u8 major;
+ u8 minor;
+} __packed;
+
+struct protocol_version {
+ u8 major;
+ u8 minor;
+} __packed;
+
+struct ili251x_data {
+ struct i2c_client *client;
+ struct input_dev *input;
+ unsigned int max_fingers;
+ bool use_pressure;
+ struct gpio_desc *reset_gpio;
+};
+
+static int ili251x_read_reg(struct i2c_client *client, u8 reg, void *buf,
+ size_t len)
+{
+ struct i2c_msg msg[2] = {
+ {
+ .addr = client->addr,
+ .flags = 0,
+ .len = 1,
+ .buf = &reg,
+ },
+ {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = len,
+ .buf = buf,
+ }
+ };
+
+ if (i2c_transfer(client->adapter, msg, 2) != 2) {
+ dev_err(&client->dev, "i2c transfer failed\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static void ili251x_report_events(struct ili251x_data *data,
+ const struct touchdata *touchdata)
+{
+ struct input_dev *input = data->input;
+ unsigned int i;
+ bool touch;
+ unsigned int x, y;
+ const struct finger *finger;
+ unsigned int reported_fingers = 0;
+
+ /* the touch chip does not count the real fingers but switches between
+ * 0, 6 and 10 reported fingers *
+ *
+ * FIXME: With a tested ili2511 we received only garbage for fingers
+ * 6-9. As workaround we add a device tree option to limit the
+ * handled number of fingers
+ */
+ if (touchdata->status == 1)
+ reported_fingers = 6;
+ else if (touchdata->status == 2)
+ reported_fingers = 10;
+
+ for (i = 0; i < reported_fingers && i < data->max_fingers; i++) {
+ input_mt_slot(input, i);
+
+ finger = &touchdata->fingers[i];
+
+ touch = finger->status;
+ input_mt_report_slot_state(input, MT_TOOL_FINGER, touch);
+ x = finger->x_low | (finger->x_high << 8);
+ y = finger->y_low | (finger->y_high << 8);
+
+ if (touch) {
+ input_report_abs(input, ABS_MT_POSITION_X, x);
+ input_report_abs(input, ABS_MT_POSITION_Y, y);
+ if (data->use_pressure)
+ input_report_abs(input, ABS_MT_PRESSURE,
+ finger->pressure);
+
+ }
+ }
+
+ input_mt_report_pointer_emulation(input, false);
+ input_sync(input);
+}
+
+static irqreturn_t ili251x_irq(int irq, void *irq_data)
+{
+ struct ili251x_data *data = irq_data;
+ struct i2c_client *client = data->client;
+ struct touchdata touchdata;
+ int error;
+
+ error = ili251x_read_reg(client, REG_TOUCHDATA,
+ &touchdata,
+ sizeof(touchdata) -
+ sizeof(struct finger)*TOUCHDATA2_FINGERS);
+
+ if (!error && touchdata.status == 2 && data->max_fingers > 6)
+ error = ili251x_read_reg(client, REG_TOUCHDATA2,
+ &touchdata.fingers[TOUCHDATA_FINGERS],
+ sizeof(struct finger)*TOUCHDATA2_FINGERS);
+
+ if (!error)
+ ili251x_report_events(data, &touchdata);
+ else
+ dev_err(&client->dev,
+ "Unable to get touchdata, err = %d\n", error);
+
+ return IRQ_HANDLED;
+}
+
+static void ili251x_reset(struct ili251x_data *data)
+{
+ if (data->reset_gpio) {
+ gpiod_set_value(data->reset_gpio, 1);
+ usleep_range(50, 100);
+ gpiod_set_value(data->reset_gpio, 0);
+ msleep(100);
+ }
+}
+
+static int ili251x_i2c_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct ili251x_data *data;
+ struct input_dev *input;
+ struct panel_info panel;
+ struct device_node *np = dev->of_node;
+ struct firmware_version firmware;
+ struct protocol_version protocol;
+ int xmax, ymax;
+ int error;
+
+ dev_dbg(dev, "Probing for ili251x I2C Touschreen driver");
+
+ if (client->irq <= 0) {
+ dev_err(dev, "No IRQ!\n");
+ return -EINVAL;
+ }
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ input = devm_input_allocate_device(dev);
+ if (!data || !input)
+ return -ENOMEM;
+
+ data->client = client;
+ data->input = input;
+ data->use_pressure = false;
+
+ data->reset_gpio = devm_gpiod_get_optional(dev, "reset",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(data->reset_gpio)) {
+ error = PTR_ERR(data->reset_gpio);
+ if (error != -EPROBE_DEFER)
+ dev_err(dev,
+ "Failed to get reset GPIO: %d\n", error);
+ return error;
+ }
+
+ ili251x_reset(data);
+
+ error = ili251x_read_reg(client, REG_FIRMWARE_VERSION,
+ &firmware, sizeof(firmware));
+ if (error) {
+ dev_err(dev, "Failed to get firmware version, err: %d\n",
+ error);
+ return error;
+ }
+
+ error = ili251x_read_reg(client, REG_PROTO_VERSION,
+ &protocol, sizeof(protocol));
+ if (error) {
+ dev_err(dev, "Failed to get protocol version, err: %d\n",
+ error);
+ return error;
+ }
+ if (protocol.major != 3) {
+ dev_err(dev, "This driver expects protocol version 3.x, Chip uses: %d\n",
+ protocol.major);
+ return -EINVAL;
+ }
+
+ error = ili251x_read_reg(client, REG_PANEL_INFO, &panel, sizeof(panel));
+ if (error) {
+ dev_err(dev, "Failed to get panel information, err: %d\n",
+ error);
+ return error;
+ }
+
+ data->max_fingers = panel.max_fingers;
+ if (np) {
+ int max_fingers;
+
+ error = of_property_read_u32(np, "max-fingers", &max_fingers);
+ if (!error && max_fingers < data->max_fingers)
+ data->max_fingers = max_fingers;
+
+ if (of_property_read_bool(np, "pressure"))
+ data->use_pressure = true;
+ }
+
+ xmax = panel.x_low | (panel.x_high << 8);
+ ymax = panel.y_low | (panel.y_high << 8);
+
+ /* Setup input device */
+ input->name = "ili251x Touchscreen";
+ input->id.bustype = BUS_I2C;
+ input->dev.parent = dev;
+
+ __set_bit(EV_SYN, input->evbit);
+ __set_bit(EV_KEY, input->evbit);
+ __set_bit(EV_ABS, input->evbit);
+ __set_bit(BTN_TOUCH, input->keybit);
+
+ /* Single touch */
+ input_set_abs_params(input, ABS_X, 0, xmax, 0, 0);
+ input_set_abs_params(input, ABS_Y, 0, ymax, 0, 0);
+
+ /* Multi touch */
+ input_mt_init_slots(input, data->max_fingers, 0);
+ input_set_abs_params(input, ABS_MT_POSITION_X, 0, xmax, 0, 0);
+ input_set_abs_params(input, ABS_MT_POSITION_Y, 0, ymax, 0, 0);
+ if (data->use_pressure)
+ input_set_abs_params(input, ABS_MT_PRESSURE, 0, U8_MAX, 0, 0);
+
+ i2c_set_clientdata(client, data);
+
+ error = devm_request_threaded_irq(dev, client->irq, NULL, ili251x_irq,
+ IRQF_ONESHOT, client->name, data);
+
+ if (error) {
+ dev_err(dev, "Unable to request touchscreen IRQ, err: %d\n",
+ error);
+ return error;
+ }
+
+ error = input_register_device(data->input);
+ if (error) {
+ dev_err(dev, "Cannot register input device, err: %d\n", error);
+ return error;
+ }
+
+ device_init_wakeup(dev, 1);
+
+ dev_info(dev,
+ "ili251x initialized (IRQ: %d), firmware version %d.%d.%d fingers %d",
+ client->irq, firmware.id, firmware.major, firmware.minor,
+ data->max_fingers);
+
+ return 0;
+}
+
+static int __maybe_unused ili251x_i2c_suspend(struct device *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+
+ if (device_may_wakeup(&client->dev))
+ enable_irq_wake(client->irq);
+
+ return 0;
+}
+
+static int __maybe_unused ili251x_i2c_resume(struct device *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+
+ if (device_may_wakeup(&client->dev))
+ disable_irq_wake(client->irq);
+
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(ili251x_i2c_pm,
+ ili251x_i2c_suspend, ili251x_i2c_resume);
+
+static const struct i2c_device_id ili251x_i2c_id[] = {
+ { "ili251x", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, ili251x_i2c_id);
+
+static struct i2c_driver ili251x_ts_driver = {
+ .driver = {
+ .name = "ili251x_i2c",
+ .pm = &ili251x_i2c_pm,
+ },
+ .id_table = ili251x_i2c_id,
+ .probe = ili251x_i2c_probe,
+};
+
+module_i2c_driver(ili251x_ts_driver);
+
+MODULE_AUTHOR("Philipp Puschmann <pp@xxxxxxxxx>");
+MODULE_DESCRIPTION("ili251x I2C Touchscreen Driver");
+MODULE_LICENSE("GPL");
--
2.17.0