[PATCH v4 0/2] Add support for Imagis touchscreens

[PATCH v4 0/2] Add support for Imagis touchscreens

[Markuss Broks]

Add support for Imagis touchscreens, used on various mobile
devices such as Samsung Galaxy J5 (2015), J3 (2015), J5 (2016).

v2: rebase on top of the correct tree
v3:
- prefix all defines as IST3038C
- use two tabs for all defines
- add missing <linux/regulator/consumer.h> header
- drop ADDR_LEN and DATA_LEN defines; use sizeof(reg_be) instead
- use __be32 type for reg_be
- add a comment about i2c read not being successful on first try
- use "ret" instead of "res" in read_reg function
- don't use the internal __cpu_to_be32 function, use cpu_to_be32 instead
- use "error" instead of "ret" in interrupt handler
- pass the slot state directly, without ternary operator
- drop the dev_err in init_input_dev function
- reorder the functions in _probe so that the chipid command is read as fast 
as possible
- don't use imagis_start in probe
- initialize the irq after the chip is powered
- save the return value in imagis_resume
- drop WIDTH_MAJOR since only TOUCH_MAJOR is reported
- the "chip detected" message is now dev_dbg
- reorder headers so they are in alphabetic order
- use GENMASK to generate masks for getting the X and Y coordinates and touch area
- drop *_pressure from device tree bindings since the driver doesn't
support reporting pressure
- fix the typo with i2c address in device treee bindings (48 instead of 50)
- add IRQF_NO_AUTOEN flag to avoid unbalanced irq enable
v4:
- alphabetically order MAINTAINERS entry
- alphabetically order Kconfig and Makefile
- drop the error message in init_regulators
- disable regulators on probe error
- drop IRQF_TRIGGER_FALLING
- @ is not optional (device tree bindings)
- don't use items for compatible
- add maxItems property to reg, drop the comment

Markuss Broks (2):
  dt-bindings: input/touchscreen: bindings for Imagis
  Input: add Imagis touchscreen driver

 .../input/touchscreen/imagis,ist3038c.yaml    |  78 +++++
 .../devicetree/bindings/vendor-prefixes.yaml  |   2 +
 MAINTAINERS                                   |   6 +
 drivers/input/touchscreen/Kconfig             |  10 +
 drivers/input/touchscreen/Makefile            |   1 +
 drivers/input/touchscreen/imagis.c            | 329 ++++++++++++++++++
 6 files changed, 426 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
 create mode 100644 drivers/input/touchscreen/imagis.c

-- 
2.35.0

[PATCH v4 1/2] dt-bindings: input/touchscreen: bindings for Imagis

[Markuss Broks]

This patch adds device-tree bindings for the Imagis
IST3038C touch screen IC.

Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
---
 .../input/touchscreen/imagis,ist3038c.yaml    | 74 +++++++++++++++++++
 .../devicetree/bindings/vendor-prefixes.yaml  |  2 +
 2 files changed, 76 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml

diff --git a/Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml b/Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
new file mode 100644
index 000000000000..f98e5dfa2bc4
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
@@ -0,0 +1,74 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/imagis,ist3038c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Imagis IST30XXC family touchscreen controller bindings
+
+maintainers:
+  - Markuss Broks <markuss.broks@gmail.com>
+
+allOf:
+  - $ref: touchscreen.yaml#
+
+properties:
+  $nodename:
+    pattern: "^touchscreen@[0-9a-f]+$"
+
+  compatible:
+    - enum:
+        - imagis,ist3038c
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  vdd-supply:
+    description: Power supply regulator for the chip
+
+  vddio-supply:
+    description: Power supply regulator for the I2C bus
+
+  touchscreen-size-x: true
+  touchscreen-size-y: true
+  touchscreen-fuzz-x: true
+  touchscreen-fuzz-y: true
+  touchscreen-inverted-x: true
+  touchscreen-inverted-y: true
+  touchscreen-swapped-x-y: true
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - touchscreen-size-x
+  - touchscreen-size-y
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      touchscreen@50 {
+        compatible = "imagis,ist3038c";
+        reg = <0x50>;
+        interrupt-parent = <&gpio>;
+        interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
+        vdd-supply = <&ldo1_reg>;
+        vddio-supply = <&ldo2_reg>;
+        touchscreen-size-x = <720>;
+        touchscreen-size-y = <1280>;
+        touchscreen-fuzz-x = <10>;
+        touchscreen-fuzz-y = <10>;
+        touchscreen-inverted-x;
+        touchscreen-inverted-y;
+      };
+    };
+
+...
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index cdc851e275f1..9357cdc5aef5 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -551,6 +551,8 @@ patternProperties:
     description: Ingenieurburo Fur Ic-Technologie (I/F/I)
   "^ilitek,.*":
     description: ILI Technology Corporation (ILITEK)
+  "^imagis,.*":
+    description: Imagis Technologies Co., Ltd.
   "^img,.*":
     description: Imagination Technologies Ltd.
   "^imi,.*":
-- 
2.35.0

[PATCH v4 2/2] Input: add Imagis touchscreen driver

[Markuss Broks]

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.

Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
---
 MAINTAINERS                        |   6 +
 drivers/input/touchscreen/Kconfig  |  10 +
 drivers/input/touchscreen/Makefile |   1 +
 drivers/input/touchscreen/imagis.c | 341 +++++++++++++++++++++++++++++
 4 files changed, 358 insertions(+)
 create mode 100644 drivers/input/touchscreen/imagis.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a899828a8d4e..3b99c60e9f4b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9411,6 +9411,12 @@ 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
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 2f6adfb7b938..a0f929506228 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/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
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 39a8127cf6a5..557f84fd2075 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/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
diff --git a/drivers/input/touchscreen/imagis.c b/drivers/input/touchscreen/imagis.c
new file mode 100644
index 000000000000..df26b90371c3
--- /dev/null
+++ b/drivers/input/touchscreen/imagis.c
@@ -0,0 +1,341 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#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		60 // ms
+#define IST3038C_I2C_RETRY_COUNT		3
+#define IST3038C_MAX_SUPPORTED_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, unsigned int *buffer)
+{
+	__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 *)buffer,
+			.len = sizeof(reg_be),
+		},
+	};
+	int ret, error;
+	int retry = IST3038C_I2C_RETRY_COUNT;
+
+	do { // The controller might need several reads until it returns a value
+		ret = i2c_transfer(ts->client->adapter, msg, ARRAY_SIZE(msg));
+		if (ret == ARRAY_SIZE(msg)) {
+			*buffer = be32_to_cpu(*buffer);
+			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;
+	unsigned int finger_status, intr_message;
+	int error, i, finger_count, finger_pressed;
+
+	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\n");
+		return IRQ_HANDLED;
+	}
+
+	finger_count = (intr_message & IST3038C_FINGER_COUNT_MASK) >> IST3038C_FINGER_COUNT_SHIFT;
+	finger_pressed = intr_message & IST3038C_FINGER_STATUS_MASK;
+	if (finger_count > IST3038C_MAX_SUPPORTED_FINGER_NUM) {
+		dev_err(&ts->client->dev, "finger count is more than maximum supported\n");
+		return IRQ_HANDLED;
+	}
+
+	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\n", i);
+			return IRQ_HANDLED;
+		}
+		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);
+
+	return IRQ_HANDLED;
+}
+
+static int imagis_start(struct imagis_ts *ts)
+{
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(ts->supplies),
+				      ts->supplies);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	msleep(IST3038C_CHIP_ON_DELAY);
+
+	enable_irq(ts->client->irq);
+	return 0;
+}
+
+static int imagis_stop(struct imagis_ts *ts)
+{
+	int error = 0;
+
+	disable_irq(ts->client->irq);
+
+	error = regulator_bulk_disable(ARRAY_SIZE(ts->supplies),
+				       ts->supplies);
+	if (error)
+		dev_err(&ts->client->dev,
+			"Failed to disable regulators: %d\n", error);
+	return error;
+}
+
+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_SUPPORTED_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;
+	int error = 0;
+
+	ts->supplies[0].supply = "vdd";
+	ts->supplies[1].supply = "vddio";
+	error = devm_regulator_bulk_get(&client->dev,
+					ARRAY_SIZE(ts->supplies),
+					ts->supplies);
+
+	return error;
+}
+
+static int imagis_probe(struct i2c_client *i2c)
+{
+	struct device *dev;
+	struct imagis_ts *ts;
+	int chip_id, ret, error;
+
+	dev = &i2c->dev;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = i2c;
+
+	ret = imagis_init_regulators(ts);
+	if (ret)
+		return dev_err_probe(dev, ret, "regulator init error: %d\n", ret);
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(ts->supplies),
+				    ts->supplies);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable regulators: %d\n", ret);
+
+	msleep(IST3038C_CHIP_ON_DELAY);
+
+	ret = imagis_i2c_read_reg(ts, IST3038C_REG_CHIPID | IST3038C_DIRECT_ACCESS, &chip_id);
+	if (ret) {
+		dev_err(dev, "chip ID read failure: %d\n", ret);
+		goto error_probe;
+	}
+
+	if (chip_id == IST3038C_WHOAMI) {
+		dev_dbg(dev, "Detected IST3038C chip\n");
+	} else {
+		dev_err(dev, "unknown chip ID: 0x%x\n", chip_id);
+		ret = -EINVAL;
+		goto error_probe;
+	}
+
+	ret = devm_request_threaded_irq(dev, i2c->irq,
+					NULL, imagis_interrupt,
+					IRQF_ONESHOT | IRQF_NO_AUTOEN,
+					"imagis-touchscreen", ts);
+	if (ret) {
+		dev_err(dev, "IRQ allocation failure: %d\n", ret);
+		goto error_probe;
+	}
+
+	ret = imagis_init_input_dev(ts);
+	if (ret) {
+		dev_err(dev, "input subsystem init error: %d\n", ret);
+		goto error_probe;
+	}
+	return 0;
+
+error_probe:
+	error = regulator_bulk_disable(ARRAY_SIZE(ts->supplies),
+				       ts->supplies);
+	if (error)
+		dev_err(dev, "Failed to disable regulators: %d\n", error);
+	return ret;
+}
+
+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);
+
+	mutex_lock(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev))
+		imagis_stop(ts);
+
+	mutex_unlock(&ts->input_dev->mutex);
+
+	return 0;
+}
+
+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 ret = 0;
+
+	mutex_lock(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev))
+		ret = imagis_start(ts);
+
+	mutex_unlock(&ts->input_dev->mutex);
+
+	return ret;
+}
+
+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(i2c, 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");
-- 
2.35.0

Re: [PATCH v4 1/2] dt-bindings: input/touchscreen: bindings for Imagis

[Krzysztof Kozlowski]

On 15/02/2022 21:51, Markuss Broks wrote:
> This patch adds device-tree bindings for the Imagis
> IST3038C touch screen IC.
> 
> Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
> ---
>  .../input/touchscreen/imagis,ist3038c.yaml    | 74 +++++++++++++++++++
>  .../devicetree/bindings/vendor-prefixes.yaml  |  2 +
>  2 files changed, 76 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml b/Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
> new file mode 100644
> index 000000000000..f98e5dfa2bc4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
> @@ -0,0 +1,74 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/touchscreen/imagis,ist3038c.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Imagis IST30XXC family touchscreen controller bindings
> +
> +maintainers:
> +  - Markuss Broks <markuss.broks@gmail.com>
> +
> +allOf:
> +  - $ref: touchscreen.yaml#
> +
> +properties:
> +  $nodename:
> +    pattern: "^touchscreen@[0-9a-f]+$"
> +
> +  compatible:
> +    - enum:

This does not work. Please test your changes. "compatible:" does not
list, so "enum" should not be an item. Drop the "-".

> +        - imagis,ist3038c
> +


Best regards,
Krzysztof