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

Dmitry Torokhov
2018-05-09T22:41:52Z

Hi Philipp,

On Mon, May 07, 2018 at 03:18:23PM +0200, Philipp Puschmann wrote:
> 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.

Is it dependent on model or what? I would much rather we did not have DT
property for this.

>
> Signed-off-by: Philipp Puschmann <pp@emlix.com>
> ---
> .../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;

This does not work on BE as the order of bits will be reversed. Please
use masks, shifts, etc instead.

> + 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;

__le16?

> + u8 y_low;
> + u8 y_high;

__le16

> + u8 xchannel_num;
> + u8 ychannel_num;
> + u8 max_fingers;
> +} __packed;

This does not need to be 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)

Please use separate tests here.

> + 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;

This is done by devm_input_allocate_device(), please drop.

> +
> + __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);

Error handling please.

The touchscreens should be marked as INPUT_MT_DIRECT.

> + 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);

You want to set up absolute axes before you call input_mt_init_slots()
so that single-touch emulation is set up properly.

> +
> + 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);

dve_dbg() if you really need this, but I would rather drop.

> +
> + 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);

All this boilerplate can be removed if you use dev_pm_set_wake_irq() in
probe().

> +
> +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@emlix.com>");
> +MODULE_DESCRIPTION("ili251x I2C Touchscreen Driver");
> +MODULE_LICENSE("GPL");
> --
> 2.17.0
>

Thanks.

--
Dmitry