Input: add MStar MSG2638 touchscreen driver

Add support for the msg2638 touchscreen IC from MStar.
Firmware handling, wakeup gestures and other specialties are not supported.
This driver reuses zinitix.c structure, while the checksum and irq handler
functions are based on out-of-tree driver for Alcatel Idol 3 (4.7").

Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210305153815.126937-2-vincent.knecht@mailoo.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/Kconfig

@@ -590,6 +590,18 @@ config TOUCHSCREEN_MELFAS_MIP4
 	  To compile this driver as a module, choose M here:
 	  the module will be called melfas_mip4.
 
+config TOUCHSCREEN_MSG2638
+	tristate "MStar msg2638 touchscreen support"
+	depends on I2C
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say Y here if you have an I2C touchscreen using MStar msg2638.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called msg2638.
+
 config TOUCHSCREEN_MTOUCH
 	tristate "MicroTouch serial touchscreens"
 	select SERIO

drivers/input/touchscreen/Makefile

@@ -58,6 +58,7 @@ obj-$(CONFIG_TOUCHSCREEN_MCS5000)	+= mcs5000_ts.o
 obj-$(CONFIG_TOUCHSCREEN_MELFAS_MIP4)	+= melfas_mip4.o
 obj-$(CONFIG_TOUCHSCREEN_MIGOR)		+= migor_ts.o
 obj-$(CONFIG_TOUCHSCREEN_MMS114)	+= mms114.o
+obj-$(CONFIG_TOUCHSCREEN_MSG2638)	+= msg2638.o
 obj-$(CONFIG_TOUCHSCREEN_MTOUCH)	+= mtouch.o
 obj-$(CONFIG_TOUCHSCREEN_MK712)		+= mk712.o
 obj-$(CONFIG_TOUCHSCREEN_HP600)		+= hp680_ts_input.o

drivers/input/touchscreen/msg2638.c

@@ -0,0 +1,337 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for MStar msg2638 touchscreens
+ *
+ * Copyright (c) 2021 Vincent Knecht <vincent.knecht@mailoo.org>
+ *
+ * Checksum and IRQ handler based on mstar_drv_common.c and
+ * mstar_drv_mutual_fw_control.c
+ * Copyright (c) 2006-2012 MStar Semiconductor, Inc.
+ *
+ * Driver structure based on zinitix.c by Michael Srba <Michael.Srba@seznam.cz>
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.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/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#define MODE_DATA_RAW			0x5A
+
+#define MAX_SUPPORTED_FINGER_NUM	5
+
+#define CHIP_ON_DELAY_MS		15
+#define FIRMWARE_ON_DELAY_MS		50
+#define RESET_DELAY_MIN_US		10000
+#define RESET_DELAY_MAX_US		11000
+
+struct packet {
+	u8	xy_hi; /* higher bits of x and y coordinates */
+	u8	x_low;
+	u8	y_low;
+	u8	pressure;
+};
+
+struct touch_event {
+	u8	mode;
+	struct	packet pkt[MAX_SUPPORTED_FINGER_NUM];
+	u8	proximity;
+	u8	checksum;
+};
+
+struct msg2638_ts_data {
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct regulator_bulk_data supplies[2];
+	struct gpio_desc *reset_gpiod;
+};
+
+static u8 msg2638_checksum(u8 *data, u32 length)
+{
+	s32 sum = 0;
+	u32 i;
+
+	for (i = 0; i < length; i++)
+		sum += data[i];
+
+	return (u8)((-sum) & 0xFF);
+}
+
+static irqreturn_t msg2638_ts_irq_handler(int irq, void *msg2638_handler)
+{
+	struct msg2638_ts_data *msg2638 = msg2638_handler;
+	struct i2c_client *client = msg2638->client;
+	struct input_dev *input = msg2638->input_dev;
+	struct touch_event touch_event;
+	u32 len = sizeof(touch_event);
+	struct i2c_msg msg[] = {
+		{
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= sizeof(touch_event),
+			.buf	= (u8 *)&touch_event,
+		},
+	};
+	struct packet *p;
+	u16 x, y;
+	int ret;
+	int i;
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret != ARRAY_SIZE(msg)) {
+		dev_err(&client->dev,
+			"Failed I2C transfer in irq handler: %d\n",
+			ret < 0 ? ret : -EIO);
+		goto out;
+	}
+
+	if (touch_event.mode != MODE_DATA_RAW)
+		goto out;
+
+	if (msg2638_checksum((u8 *)&touch_event, len - 1) !=
+						touch_event.checksum) {
+		dev_err(&client->dev, "Failed checksum!\n");
+		goto out;
+	}
+
+	for (i = 0; i < MAX_SUPPORTED_FINGER_NUM; i++) {
+		p = &touch_event.pkt[i];
+
+		/* Ignore non-pressed finger data */
+		if (p->xy_hi == 0xFF && p->x_low == 0xFF && p->y_low == 0xFF)
+			continue;
+
+		x = (((p->xy_hi & 0xF0) << 4) | p->x_low);
+		y = (((p->xy_hi & 0x0F) << 8) | p->y_low);
+
+		input_mt_slot(input, i);
+		input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
+		touchscreen_report_pos(input, &msg2638->prop, x, y, true);
+	}
+
+	input_mt_sync_frame(msg2638->input_dev);
+	input_sync(msg2638->input_dev);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static void msg2638_reset(struct msg2638_ts_data *msg2638)
+{
+	gpiod_set_value_cansleep(msg2638->reset_gpiod, 1);
+	usleep_range(RESET_DELAY_MIN_US, RESET_DELAY_MAX_US);
+	gpiod_set_value_cansleep(msg2638->reset_gpiod, 0);
+	msleep(FIRMWARE_ON_DELAY_MS);
+}
+
+static int msg2638_start(struct msg2638_ts_data *msg2638)
+{
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(msg2638->supplies),
+				      msg2638->supplies);
+	if (error) {
+		dev_err(&msg2638->client->dev,
+			"Failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	msleep(CHIP_ON_DELAY_MS);
+
+	msg2638_reset(msg2638);
+
+	enable_irq(msg2638->client->irq);
+
+	return 0;
+}
+
+static int msg2638_stop(struct msg2638_ts_data *msg2638)
+{
+	int error;
+
+	disable_irq(msg2638->client->irq);
+
+	error = regulator_bulk_disable(ARRAY_SIZE(msg2638->supplies),
+				       msg2638->supplies);
+	if (error) {
+		dev_err(&msg2638->client->dev,
+			"Failed to disable regulators: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int msg2638_input_open(struct input_dev *dev)
+{
+	struct msg2638_ts_data *msg2638 = input_get_drvdata(dev);
+
+	return msg2638_start(msg2638);
+}
+
+static void msg2638_input_close(struct input_dev *dev)
+{
+	struct msg2638_ts_data *msg2638 = input_get_drvdata(dev);
+
+	msg2638_stop(msg2638);
+}
+
+static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
+{
+	struct device *dev = &msg2638->client->dev;
+	struct input_dev *input_dev;
+	int error;
+
+	input_dev = devm_input_allocate_device(dev);
+	if (!input_dev) {
+		dev_err(dev, "Failed to allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	input_set_drvdata(input_dev, msg2638);
+	msg2638->input_dev = input_dev;
+
+	input_dev->name = "MStar TouchScreen";
+	input_dev->phys = "input/ts";
+	input_dev->id.bustype = BUS_I2C;
+	input_dev->open = msg2638_input_open;
+	input_dev->close = msg2638_input_close;
+
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
+
+	touchscreen_parse_properties(input_dev, true, &msg2638->prop);
+	if (!msg2638->prop.max_x || !msg2638->prop.max_y) {
+		dev_err(dev, "touchscreen-size-x and/or touchscreen-size-y not set in properties\n");
+		return -EINVAL;
+	}
+
+	error = input_mt_init_slots(input_dev, MAX_SUPPORTED_FINGER_NUM,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error) {
+		dev_err(dev, "Failed to initialize MT slots: %d\n", error);
+		return error;
+	}
+
+	error = input_register_device(input_dev);
+	if (error) {
+		dev_err(dev, "Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int msg2638_ts_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct msg2638_ts_data *msg2638;
+	int error;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(dev, "Failed to assert adapter's support for plain I2C.\n");
+		return -ENXIO;
+	}
+
+	msg2638 = devm_kzalloc(dev, sizeof(*msg2638), GFP_KERNEL);
+	if (!msg2638)
+		return -ENOMEM;
+
+	msg2638->client = client;
+	i2c_set_clientdata(client, msg2638);
+
+	msg2638->supplies[0].supply = "vdd";
+	msg2638->supplies[1].supply = "vddio";
+	error = devm_regulator_bulk_get(dev, ARRAY_SIZE(msg2638->supplies),
+					msg2638->supplies);
+	if (error) {
+		dev_err(dev, "Failed to get regulators: %d\n", error);
+		return error;
+	}
+
+	msg2638->reset_gpiod = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(msg2638->reset_gpiod)) {
+		error = PTR_ERR(msg2638->reset_gpiod);
+		dev_err(dev, "Failed to request reset GPIO: %d\n", error);
+		return error;
+	}
+
+	error = msg2638_init_input_dev(msg2638);
+	if (error) {
+		dev_err(dev, "Failed to initialize input device: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(dev, client->irq,
+					  NULL, msg2638_ts_irq_handler,
+					  IRQF_ONESHOT | IRQF_NO_AUTOEN,
+					  client->name, msg2638);
+	if (error) {
+		dev_err(dev, "Failed to request IRQ: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int __maybe_unused msg2638_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct msg2638_ts_data *msg2638 = i2c_get_clientdata(client);
+
+	mutex_lock(&msg2638->input_dev->mutex);
+
+	if (input_device_enabled(msg2638->input_dev))
+		msg2638_stop(msg2638);
+
+	mutex_unlock(&msg2638->input_dev->mutex);
+
+	return 0;
+}
+
+static int __maybe_unused msg2638_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct msg2638_ts_data *msg2638 = i2c_get_clientdata(client);
+	int ret = 0;
+
+	mutex_lock(&msg2638->input_dev->mutex);
+
+	if (input_device_enabled(msg2638->input_dev))
+		ret = msg2638_start(msg2638);
+
+	mutex_unlock(&msg2638->input_dev->mutex);
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(msg2638_pm_ops, msg2638_suspend, msg2638_resume);
+
+static const struct of_device_id msg2638_of_match[] = {
+	{ .compatible = "mstar,msg2638" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, msg2638_of_match);
+
+static struct i2c_driver msg2638_ts_driver = {
+	.probe_new = msg2638_ts_probe,
+	.driver = {
+		.name = "MStar-TS",
+		.pm = &msg2638_pm_ops,
+		.of_match_table = msg2638_of_match,
+	},
+};
+module_i2c_driver(msg2638_ts_driver);
+
+MODULE_AUTHOR("Vincent Knecht <vincent.knecht@mailoo.org>");
+MODULE_DESCRIPTION("MStar MSG2638 touchscreen driver");
+MODULE_LICENSE("GPL v2");