Input: add Imagis touchscreen driver

Add support for the IST3038C touchscreen IC from Imagis, based on
downstream driver. The driver supports multi-touch (10 touch points)
The IST3038C IC supports touch keys, but the support isn't added
because the touch screen used for testing doesn't utilize touch keys.
Looking at the downstream driver, it is possible to add support
for other Imagis ICs of IST30**C series.
Reviewed-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
Link: https://lore.kernel.org/r/20220305165330.13061-3-markuss.broks@gmail.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

MAINTAINERS

@@ -9370,6 +9370,12 @@ M:	Stanislaw Gruszka <stf_xl@wp.pl>
 S:	Maintained
 F:	drivers/usb/atm/ueagle-atm.c
 
+IMAGIS TOUCHSCREEN DRIVER
+M:	Markuss Broks <markuss.broks@gmail.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
+F:	drivers/input/touchscreen/imagis.c
+
 IMGTEC ASCII LCD DRIVER
 M:	Paul Burton <paulburton@kernel.org>
 S:	Maintained

drivers/input/touchscreen/Kconfig

@@ -638,6 +638,16 @@ config TOUCHSCREEN_MTOUCH
 	  To compile this driver as a module, choose M here: the
 	  module will be called mtouch.
 
+config TOUCHSCREEN_IMAGIS
+	tristate "Imagis touchscreen support"
+	depends on I2C
+	help
+	  Say Y here if you have an Imagis IST30xxC touchscreen.
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called imagis.
+
 config TOUCHSCREEN_IMX6UL_TSC
 	tristate "Freescale i.MX6UL touchscreen controller"
 	depends on ((OF && GPIOLIB) || COMPILE_TEST) && HAS_IOMEM

drivers/input/touchscreen/Makefile

@@ -49,6 +49,7 @@ obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
+obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o
 obj-$(CONFIG_TOUCHSCREEN_IMX6UL_TSC)	+= imx6ul_tsc.o
 obj-$(CONFIG_TOUCHSCREEN_INEXIO)	+= inexio.o
 obj-$(CONFIG_TOUCHSCREEN_IPROC)		+= bcm_iproc_tsc.o

drivers/input/touchscreen/imagis.c

+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+
+#define IST3038C_HIB_ACCESS		(0x800B << 16)
+#define IST3038C_DIRECT_ACCESS		BIT(31)
+#define IST3038C_REG_CHIPID		0x40001000
+#define IST3038C_REG_HIB_BASE		0x30000100
+#define IST3038C_REG_TOUCH_STATUS	(IST3038C_REG_HIB_BASE | IST3038C_HIB_ACCESS)
+#define IST3038C_REG_TOUCH_COORD	(IST3038C_REG_HIB_BASE | IST3038C_HIB_ACCESS | 0x8)
+#define IST3038C_REG_INTR_MESSAGE	(IST3038C_REG_HIB_BASE | IST3038C_HIB_ACCESS | 0x4)
+#define IST3038C_WHOAMI			0x38c
+#define IST3038C_CHIP_ON_DELAY_MS	60
+#define IST3038C_I2C_RETRY_COUNT	3
+#define IST3038C_MAX_FINGER_NUM		10
+#define IST3038C_X_MASK			GENMASK(23, 12)
+#define IST3038C_X_SHIFT		12
+#define IST3038C_Y_MASK			GENMASK(11, 0)
+#define IST3038C_AREA_MASK		GENMASK(27, 24)
+#define IST3038C_AREA_SHIFT		24
+#define IST3038C_FINGER_COUNT_MASK	GENMASK(15, 12)
+#define IST3038C_FINGER_COUNT_SHIFT	12
+#define IST3038C_FINGER_STATUS_MASK	GENMASK(9, 0)
+
+struct imagis_ts {
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct regulator_bulk_data supplies[2];
+};
+
+static int imagis_i2c_read_reg(struct imagis_ts *ts,
+			       unsigned int reg, u32 *data)
+{
+	__be32 ret_be;
+	__be32 reg_be = cpu_to_be32(reg);
+	struct i2c_msg msg[] = {
+		{
+			.addr = ts->client->addr,
+			.flags = 0,
+			.buf = (unsigned char *)&reg_be,
+			.len = sizeof(reg_be),
+		}, {
+			.addr = ts->client->addr,
+			.flags = I2C_M_RD,
+			.buf = (unsigned char *)&ret_be,
+			.len = sizeof(ret_be),
+		},
+	};
+	int ret, error;
+	int retry = IST3038C_I2C_RETRY_COUNT;
+
+	/* Retry in case the controller fails to respond */
+	do {
+		ret = i2c_transfer(ts->client->adapter, msg, ARRAY_SIZE(msg));
+		if (ret == ARRAY_SIZE(msg)) {
+			*data = be32_to_cpu(ret_be);
+			return 0;
+		}
+
+		error = ret < 0 ? ret : -EIO;
+		dev_err(&ts->client->dev,
+			"%s - i2c_transfer failed: %d (%d)\n",
+			__func__, error, ret);
+	} while (--retry);
+
+	return error;
+}
+
+static irqreturn_t imagis_interrupt(int irq, void *dev_id)
+{
+	struct imagis_ts *ts = dev_id;
+	u32 intr_message, finger_status;
+	unsigned int finger_count, finger_pressed;
+	int i;
+	int error;
+
+	error = imagis_i2c_read_reg(ts, IST3038C_REG_INTR_MESSAGE,
+				    &intr_message);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"failed to read the interrupt message: %d\n", error);
+		goto out;
+	}
+
+	finger_count = (intr_message & IST3038C_FINGER_COUNT_MASK) >>
+				IST3038C_FINGER_COUNT_SHIFT;
+	if (finger_count > IST3038C_MAX_FINGER_NUM) {
+		dev_err(&ts->client->dev,
+			"finger count %d is more than maximum supported\n",
+			finger_count);
+		goto out;
+	}
+
+	finger_pressed = intr_message & IST3038C_FINGER_STATUS_MASK;
+
+	for (i = 0; i < finger_count; i++) {
+		error = imagis_i2c_read_reg(ts,
+					    IST3038C_REG_TOUCH_COORD + (i * 4),
+					    &finger_status);
+		if (error) {
+			dev_err(&ts->client->dev,
+				"failed to read coordinates for finger %d: %d\n",
+				i, error);
+			goto out;
+		}
+
+		input_mt_slot(ts->input_dev, i);
+		input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER,
+					   finger_pressed & BIT(i));
+		touchscreen_report_pos(ts->input_dev, &ts->prop,
+				       (finger_status & IST3038C_X_MASK) >>
+						IST3038C_X_SHIFT,
+				       finger_status & IST3038C_Y_MASK, 1);
+		input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR,
+				 (finger_status & IST3038C_AREA_MASK) >>
+					IST3038C_AREA_SHIFT);
+	}
+
+	input_mt_sync_frame(ts->input_dev);
+	input_sync(ts->input_dev);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static void imagis_power_off(void *_ts)
+{
+	struct imagis_ts *ts = _ts;
+
+	regulator_bulk_disable(ARRAY_SIZE(ts->supplies), ts->supplies);
+}
+
+static int imagis_power_on(struct imagis_ts *ts)
+{
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(ts->supplies), ts->supplies);
+	if (error)
+		return error;
+
+	msleep(IST3038C_CHIP_ON_DELAY_MS);
+
+	return 0;
+}
+
+static int imagis_start(struct imagis_ts *ts)
+{
+	int error;
+
+	error = imagis_power_on(ts);
+	if (error)
+		return error;
+
+	enable_irq(ts->client->irq);
+
+	return 0;
+}
+
+static int imagis_stop(struct imagis_ts *ts)
+{
+	disable_irq(ts->client->irq);
+
+	imagis_power_off(ts);
+
+	return 0;
+}
+
+static int imagis_input_open(struct input_dev *dev)
+{
+	struct imagis_ts *ts = input_get_drvdata(dev);
+
+	return imagis_start(ts);
+}
+
+static void imagis_input_close(struct input_dev *dev)
+{
+	struct imagis_ts *ts = input_get_drvdata(dev);
+
+	imagis_stop(ts);
+}
+
+static int imagis_init_input_dev(struct imagis_ts *ts)
+{
+	struct input_dev *input_dev;
+	int error;
+
+	input_dev = devm_input_allocate_device(&ts->client->dev);
+	if (!input_dev)
+		return -ENOMEM;
+
+	ts->input_dev = input_dev;
+
+	input_dev->name = "Imagis capacitive touchscreen";
+	input_dev->phys = "input/ts";
+	input_dev->id.bustype = BUS_I2C;
+	input_dev->open = imagis_input_open;
+	input_dev->close = imagis_input_close;
+
+	input_set_drvdata(input_dev, ts);
+
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
+
+	touchscreen_parse_properties(input_dev, true, &ts->prop);
+	if (!ts->prop.max_x || !ts->prop.max_y) {
+		dev_err(&ts->client->dev,
+			"Touchscreen-size-x and/or touchscreen-size-y not set in dts\n");
+		return -EINVAL;
+	}
+
+	error = input_mt_init_slots(input_dev,
+				    IST3038C_MAX_FINGER_NUM,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to initialize MT slots: %d", error);
+		return error;
+	}
+
+	error = input_register_device(input_dev);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to register input device: %d", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int imagis_init_regulators(struct imagis_ts *ts)
+{
+	struct i2c_client *client = ts->client;
+
+	ts->supplies[0].supply = "vdd";
+	ts->supplies[1].supply = "vddio";
+	return devm_regulator_bulk_get(&client->dev,
+				       ARRAY_SIZE(ts->supplies),
+				       ts->supplies);
+}
+
+static int imagis_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct imagis_ts *ts;
+	int chip_id, error;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = i2c;
+
+	error = imagis_init_regulators(ts);
+	if (error) {
+		dev_err(dev, "regulator init error: %d\n", error);
+		return error;
+	}
+
+	error = imagis_power_on(ts);
+	if (error) {
+		dev_err(dev, "failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	error = devm_add_action_or_reset(dev, imagis_power_off, ts);
+	if (error) {
+		dev_err(dev, "failed to install poweroff action: %d\n", error);
+		return error;
+	}
+
+	error = imagis_i2c_read_reg(ts,
+			IST3038C_REG_CHIPID | IST3038C_DIRECT_ACCESS,
+			&chip_id);
+	if (error) {
+		dev_err(dev, "chip ID read failure: %d\n", error);
+		return error;
+	}
+
+	if (chip_id != IST3038C_WHOAMI) {
+		dev_err(dev, "unknown chip ID: 0x%x\n", chip_id);
+		return -EINVAL;
+	}
+
+	error = devm_request_threaded_irq(dev, i2c->irq,
+					  NULL, imagis_interrupt,
+					  IRQF_ONESHOT | IRQF_NO_AUTOEN,
+					  "imagis-touchscreen", ts);
+	if (error) {
+		dev_err(dev, "IRQ %d allocation failure: %d\n",
+			i2c->irq, error);
+		return error;
+	}
+
+	error = imagis_init_input_dev(ts);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static int __maybe_unused imagis_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct imagis_ts *ts = i2c_get_clientdata(client);
+	int retval = 0;
+
+	mutex_lock(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev))
+		retval = imagis_stop(ts);
+
+	mutex_unlock(&ts->input_dev->mutex);
+
+	return retval;
+}
+
+static int __maybe_unused imagis_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct imagis_ts *ts = i2c_get_clientdata(client);
+	int retval = 0;
+
+	mutex_lock(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev))
+		retval = imagis_start(ts);
+
+	mutex_unlock(&ts->input_dev->mutex);
+
+	return retval;
+}
+
+static SIMPLE_DEV_PM_OPS(imagis_pm_ops, imagis_suspend, imagis_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id imagis_of_match[] = {
+	{ .compatible = "imagis,ist3038c", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, imagis_of_match);
+#endif
+
+static struct i2c_driver imagis_ts_driver = {
+	.driver = {
+		.name = "imagis-touchscreen",
+		.pm = &imagis_pm_ops,
+		.of_match_table = of_match_ptr(imagis_of_match),
+	},
+	.probe_new = imagis_probe,
+};
+
+module_i2c_driver(imagis_ts_driver);
+
+MODULE_DESCRIPTION("Imagis IST3038C Touchscreen Driver");
+MODULE_AUTHOR("Markuss Broks <markuss.broks@gmail.com>");
+MODULE_LICENSE("GPL");