[PATCH v4 0/3] Add Himax hx83112b touchscreen driver

[PATCH v4 0/3] Add Himax hx83112b touchscreen driver

[Job Noorman]

Hi all,

This series adds support for the Himax hx83112b. The hx83112b supports 10
point multitouch with hardware tracking of touch points. It is the
touchschreen used by the Fairphone 3.

Note that a datasheet was unavailable for this device, so it was built
based on the Android driver that was tagged as GPLv2. This series is a
complete rewrite, though, and the code bears no resemblence to the original
implementation.

It is expected that this driver can be made to work on other hx83xxx
devices, especially the hx83112a used in the Fairphone 4. However, since we
have been unable to verify this, this driver only declares compatibility
with the hx83112b and uses very specific file names.

Changes since v3 (based on Dmitry Torokhov's comments):
- Use gpiod_set_value_cansleep (instead of gpiod_set_value) during probe
- Inline some small helper functions
- Use DEFINE_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr()
- Use PTR_ERR_OR_ZERO instead of IS_ERR+PTR_ERR
- Some minor coding style updates (e.g., use C-style comments)

Changes since v2 (based on Jeff LaBundy's comments):
- Kconfig: depend on REGMAP_I2C instead of I2C
- Don't use dev_err_probe()
- Return IRQ_NONE on failed register reads to prevent possible interrupt
  storm
- Add small delay after de-asserting reset pin
- Some minor coding style updates
- dt-bindings: make touchscreen-size-{x,y} required

Changes since v1:
- Fix sparse warnings. Reported-by: kernel test robot <lkp@intel.com>.
- Fix dt_binding_check.

Best regards,
Job

Previous versions:
- v3: https://lore.kernel.org/lkml/20221016102756.40345-1-job@noorman.info/
- v2: https://lore.kernel.org/lkml/20221012202341.295351-1-job@noorman.info/
- v1: https://lore.kernel.org/lkml/20221011190729.14747-1-job@noorman.info/

Job Noorman (3):
  dt-bindings: touchscreen: add Himax hx83112b bindings
  Input: add driver for Himax hx83112b touchscreen devices
  arm64: dts: qcom: sdm632: fairphone-fp3: add touchscreen

 .../input/touchscreen/himax,hx83112b.yaml     |  63 +++
 MAINTAINERS                                   |   7 +
 .../boot/dts/qcom/sdm632-fairphone-fp3.dts    |  14 +
 drivers/input/touchscreen/Kconfig             |  11 +
 drivers/input/touchscreen/Makefile            |   1 +
 drivers/input/touchscreen/himax_hx83112b.c    | 367 ++++++++++++++++++
 6 files changed, 463 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml
 create mode 100644 drivers/input/touchscreen/himax_hx83112b.c


base-commit: d4a596eddb90114f5f5f32a440057a175517b090
-- 
2.38.0

[PATCH v4 1/3] dt-bindings: touchscreen: add Himax hx83112b bindings

[Job Noorman]

This patch adds device tree bindings for Himax 83112b touchscreen
devices.

Signed-off-by: Job Noorman <job@noorman.info>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../input/touchscreen/himax,hx83112b.yaml     | 63 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 69 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml

diff --git a/Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml b/Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml
new file mode 100644
index 000000000000..be2ba185c086
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml
@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/himax,hx83112b.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Himax hx83112b touchscreen controller bindings
+
+maintainers:
+  - Job Noorman <job@noorman.info>
+
+allOf:
+  - $ref: touchscreen.yaml#
+
+properties:
+  compatible:
+    enum:
+      - himax,hx83112b
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+
+  touchscreen-inverted-x: true
+  touchscreen-inverted-y: true
+  touchscreen-size-x: true
+  touchscreen-size-y: true
+  touchscreen-swapped-x-y: true
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - reset-gpios
+  - touchscreen-size-x
+  - touchscreen-size-y
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/gpio/gpio.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      touchscreen@48 {
+        compatible = "himax,hx83112b";
+        reg = <0x48>;
+        interrupt-parent = <&tlmm>;
+        interrupts = <65 IRQ_TYPE_LEVEL_LOW>;
+        touchscreen-size-x = <1080>;
+        touchscreen-size-y = <2160>;
+        reset-gpios = <&tlmm 64 GPIO_ACTIVE_LOW>;
+      };
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 9ddcc242081c..2418bffe9187 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9094,6 +9094,12 @@ W:	http://www.highpoint-tech.com
 F:	Documentation/scsi/hptiop.rst
 F:	drivers/scsi/hptiop.c
 
+HIMAX HX83112B TOUCHSCREEN SUPPORT
+M:	Job Noorman <job@noorman.info>
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml
+
 HIPPI
 M:	Jes Sorensen <jes@trained-monkey.org>
 L:	linux-hippi@sunsite.dk
-- 
2.38.0

[PATCH v4 2/3] Input: add driver for Himax hx83112b touchscreen devices

[Job Noorman]

This patch adds support for Himax hx83112b touchscreen devices. As there
are no publicly available data sheets for these devices, the
implementation is based on the driver of the downstream Android kernel
used in the Fairphone 3. This patch is a complete rewrite, though, and
the code bears no resemblence to the original implementation.

The driver has been tested on the aforementioned phone.

Signed-off-by: Job Noorman <job@noorman.info>
---
 MAINTAINERS                                |   1 +
 drivers/input/touchscreen/Kconfig          |  11 +
 drivers/input/touchscreen/Makefile         |   1 +
 drivers/input/touchscreen/himax_hx83112b.c | 367 +++++++++++++++++++++
 4 files changed, 380 insertions(+)
 create mode 100644 drivers/input/touchscreen/himax_hx83112b.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 2418bffe9187..51a03f9586f1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9099,6 +9099,7 @@ M:	Job Noorman <job@noorman.info>
 L:	linux-input@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml
+F:	drivers/input/touchscreen/himax_hx83112b.c
 
 HIPPI
 M:	Jes Sorensen <jes@trained-monkey.org>
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index dc90a3ea51ee..113b7dd7da2f 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -1379,4 +1379,15 @@ config TOUCHSCREEN_ZINITIX
 	  To compile this driver as a module, choose M here: the
 	  module will be called zinitix.
 
+config TOUCHSCREEN_HIMAX_HX83112B
+	tristate "Himax hx83112b touchscreen driver"
+	depends on REGMAP_I2C
+	help
+	  Say Y here to enable support for Himax hx83112b touchscreens.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called himax_hx83112b.
+
 endif
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 557f84fd2075..0f8bf79e01fe 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -116,3 +116,4 @@ obj-$(CONFIG_TOUCHSCREEN_ROHM_BU21023)	+= rohm_bu21023.o
 obj-$(CONFIG_TOUCHSCREEN_RASPBERRYPI_FW)	+= raspberrypi-ts.o
 obj-$(CONFIG_TOUCHSCREEN_IQS5XX)	+= iqs5xx.o
 obj-$(CONFIG_TOUCHSCREEN_ZINITIX)	+= zinitix.o
+obj-$(CONFIG_TOUCHSCREEN_HIMAX_HX83112B)	+= himax_hx83112b.o
diff --git a/drivers/input/touchscreen/himax_hx83112b.c b/drivers/input/touchscreen/himax_hx83112b.c
new file mode 100644
index 000000000000..6f76fe48cfdd
--- /dev/null
+++ b/drivers/input/touchscreen/himax_hx83112b.c
@@ -0,0 +1,367 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Himax hx83112b touchscreens
+ *
+ * Copyright (C) 2022 Job Noorman <job@noorman.info>
+ *
+ * This code is based on "Himax Android Driver Sample Code for QCT platform":
+ *
+ * Copyright (C) 2017 Himax Corporation.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.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/regmap.h>
+
+#define HIMAX_ID_83112B 0x83112b
+
+#define HIMAX_MAX_POINTS 10
+
+
+#define HIMAX_REG_CFG_SET_ADDR	 0x00
+#define HIMAX_REG_CFG_INIT_READ	 0x0c
+#define HIMAX_REG_CFG_READ_VALUE 0x08
+#define HIMAX_REG_READ_EVENT	 0x30
+
+#define HIMAX_CFG_PRODUCT_ID 0x900000d0
+
+#define HIMAX_INVALID_COORD 0xffff
+
+struct himax_event_point {
+	__be16 x;
+	__be16 y;
+} __packed;
+
+struct himax_event {
+	struct himax_event_point points[HIMAX_MAX_POINTS];
+	u8 majors[HIMAX_MAX_POINTS];
+	u8 pad0[2];
+	u8 num_points;
+	u8 pad1[2];
+	u8 checksum_fix;
+} __packed;
+
+static_assert(sizeof(struct himax_event) == 56);
+
+struct himax_ts_data {
+	struct gpio_desc *gpiod_rst;
+	struct input_dev *input_dev;
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct touchscreen_properties props;
+};
+
+static const struct regmap_config himax_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 32,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+};
+
+static int himax_read_config(struct himax_ts_data *ts, u32 address, u32 *dst)
+{
+	int error;
+
+	error = regmap_write(ts->regmap, HIMAX_REG_CFG_SET_ADDR, address);
+	if (error)
+		return error;
+
+	error = regmap_write(ts->regmap, HIMAX_REG_CFG_INIT_READ, 0x0);
+	if (error)
+		return error;
+
+	error = regmap_read(ts->regmap, HIMAX_REG_CFG_READ_VALUE, dst);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static void himax_reset(struct himax_ts_data *ts)
+{
+	gpiod_set_value_cansleep(ts->gpiod_rst, 1);
+
+	/* Delay copied from downstream driver */
+	msleep(20);
+	gpiod_set_value_cansleep(ts->gpiod_rst, 0);
+
+	/*
+	 * The downstream driver doesn't contain this delay but is seems safer
+	 * to include it. The range is just a guess that seems to work well.
+	 */
+	usleep_range(1000, 1100);
+}
+
+static int himax_read_product_id(struct himax_ts_data *ts, u32 *product_id)
+{
+	int error;
+
+	error = himax_read_config(ts, HIMAX_CFG_PRODUCT_ID, product_id);
+	if (error)
+		return error;
+
+	*product_id >>= 8;
+	return 0;
+}
+
+static int himax_check_product_id(struct himax_ts_data *ts)
+{
+	int error;
+	u32 product_id;
+
+	error = himax_read_product_id(ts, &product_id);
+	if (error)
+		return error;
+
+	dev_dbg(&ts->client->dev, "Product id: %x\n", product_id);
+
+	switch (product_id) {
+	case HIMAX_ID_83112B:
+		return 0;
+
+	default:
+		dev_err(&ts->client->dev,
+			"Unknown product id: %x\n", product_id);
+		return -EINVAL;
+	}
+}
+
+static int himax_input_register(struct himax_ts_data *ts)
+{
+	int error;
+
+	ts->input_dev = devm_input_allocate_device(&ts->client->dev);
+	if (!ts->input_dev) {
+		dev_err(&ts->client->dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	ts->input_dev->name = "Himax Touchscreen";
+
+	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(ts->input_dev, ABS_MT_WIDTH_MAJOR, 0, 200, 0, 0);
+	input_set_abs_params(ts->input_dev, ABS_MT_TOUCH_MAJOR, 0, 200, 0, 0);
+
+	touchscreen_parse_properties(ts->input_dev, true, &ts->props);
+
+	error = input_mt_init_slots(ts->input_dev, HIMAX_MAX_POINTS,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to initialize MT slots: %d\n", error);
+		return error;
+	}
+
+	error = input_register_device(ts->input_dev);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static u8 himax_event_get_num_points(const struct himax_event *event)
+{
+	if (event->num_points == 0xff)
+		return 0;
+	else
+		return event->num_points & 0x0f;
+}
+
+static bool himax_process_event_point(struct himax_ts_data *ts,
+				      const struct himax_event *event,
+				      int point_index)
+{
+	const struct himax_event_point *point = &event->points[point_index];
+	u16 x = be16_to_cpu(point->x);
+	u16 y = be16_to_cpu(point->y);
+	u8 w = event->majors[point_index];
+
+	if (x == HIMAX_INVALID_COORD || y == HIMAX_INVALID_COORD)
+		return false;
+
+	input_mt_slot(ts->input_dev, point_index);
+	input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER, true);
+	touchscreen_report_pos(ts->input_dev, &ts->props, x, y, true);
+	input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR, w);
+	input_report_abs(ts->input_dev, ABS_MT_WIDTH_MAJOR, w);
+	return true;
+}
+
+static void himax_process_event(struct himax_ts_data *ts,
+				const struct himax_event *event)
+{
+	int i;
+	int num_points_left = himax_event_get_num_points(event);
+
+	for (i = 0; i < HIMAX_MAX_POINTS && num_points_left > 0; i++) {
+		if (himax_process_event_point(ts, event, i))
+			num_points_left--;
+	}
+
+	input_mt_sync_frame(ts->input_dev);
+	input_sync(ts->input_dev);
+}
+
+static bool himax_verify_checksum(struct himax_ts_data *ts,
+				  const struct himax_event *event)
+{
+	u8 *data = (u8 *)event;
+	int i;
+	u16 checksum = 0;
+
+	for (i = 0; i < sizeof(*event); i++)
+		checksum += data[i];
+
+	if ((checksum & 0x00ff) != 0) {
+		dev_err(&ts->client->dev, "Wrong event checksum: %04x\n",
+			checksum);
+		return false;
+	}
+
+	return true;
+}
+
+static int himax_handle_input(struct himax_ts_data *ts)
+{
+	int error;
+	struct himax_event event;
+
+	error = regmap_raw_read(ts->regmap, HIMAX_REG_READ_EVENT, &event,
+				sizeof(event));
+	if (error) {
+		dev_err(&ts->client->dev, "Failed to read input event: %d\n",
+			error);
+		return error;
+	}
+
+	if (!himax_verify_checksum(ts, &event)) {
+		/*
+		 * We cannot process the current event when it has an invalid
+		 * checksum but we don't consider this a fatal error.
+		 */
+		return 0;
+	}
+
+	himax_process_event(ts, &event);
+	return 0;
+}
+
+static irqreturn_t himax_irq_handler(int irq, void *dev_id)
+{
+	struct himax_ts_data *ts = dev_id;
+	int error = himax_handle_input(ts);
+
+	if (error)
+		return IRQ_NONE;
+
+	return IRQ_HANDLED;
+}
+
+static int himax_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	int error;
+	struct device *dev = &client->dev;
+	struct himax_ts_data *ts;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(dev, "I2C check functionality failed\n");
+		return -ENXIO;
+	}
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, ts);
+	ts->client = client;
+
+	ts->regmap = devm_regmap_init_i2c(client, &himax_regmap_config);
+	error = PTR_ERR_OR_ZERO(ts->regmap);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to initialize regmap: %d\n", error);
+		return error;
+	}
+
+	ts->gpiod_rst = devm_gpiod_get(&ts->client->dev, "reset",
+				       GPIOD_OUT_HIGH);
+	error = PTR_ERR_OR_ZERO(ts->gpiod_rst);
+	if (error) {
+		if (error != -EPROBE_DEFER)
+			dev_err(&ts->client->dev,
+				"Failed to get reset GPIO: %d\n", error);
+		return error;
+	}
+
+	himax_reset(ts);
+
+	error = himax_check_product_id(ts);
+	if (error)
+		return error;
+
+	error = himax_input_register(ts);
+	if (error)
+		return error;
+
+	return devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					 himax_irq_handler, IRQF_ONESHOT,
+					 client->name, ts);
+}
+
+static int himax_suspend(struct device *dev)
+{
+	struct himax_ts_data *ts = dev_get_drvdata(dev);
+
+	disable_irq(ts->client->irq);
+	return 0;
+}
+
+static int himax_resume(struct device *dev)
+{
+	struct himax_ts_data *ts = dev_get_drvdata(dev);
+
+	enable_irq(ts->client->irq);
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(himax_pm_ops, himax_suspend, himax_resume);
+
+static const struct i2c_device_id himax_ts_id[] = {
+	{ "hx83112b", 0 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, himax_ts_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id himax_of_match[] = {
+	{ .compatible = "himax,hx83112b" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, himax_of_match);
+#endif
+
+static struct i2c_driver himax_ts_driver = {
+	.probe = himax_probe,
+	.id_table = himax_ts_id,
+	.driver = {
+		.name = "Himax-hx83112b-TS",
+		.of_match_table = of_match_ptr(himax_of_match),
+		.pm = pm_sleep_ptr(&himax_pm_ops),
+	},
+};
+module_i2c_driver(himax_ts_driver);
+
+MODULE_AUTHOR("Job Noorman <job@noorman.info>");
+MODULE_DESCRIPTION("Himax hx83112b touchscreen driver");
+MODULE_LICENSE("GPL");
-- 
2.38.0

[PATCH v4 3/3] arm64: dts: qcom: sdm632: fairphone-fp3: add touchscreen

[Job Noorman]

Add Himax hx83112b touchscreen to the FP3 DT.

Signed-off-by: Job Noorman <job@noorman.info>
---
 arch/arm64/boot/dts/qcom/sdm632-fairphone-fp3.dts | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm632-fairphone-fp3.dts b/arch/arm64/boot/dts/qcom/sdm632-fairphone-fp3.dts
index 891e314bc782..2920504461d3 100644
--- a/arch/arm64/boot/dts/qcom/sdm632-fairphone-fp3.dts
+++ b/arch/arm64/boot/dts/qcom/sdm632-fairphone-fp3.dts
@@ -49,6 +49,20 @@ &hsusb_phy {
 	vdda-phy-dpdm-supply = <&pm8953_l13>;
 };
 
+&i2c_3 {
+	status = "okay";
+
+	touchscreen@48 {
+		compatible = "himax,hx83112b";
+		reg = <0x48>;
+		interrupt-parent = <&tlmm>;
+		interrupts = <65 IRQ_TYPE_LEVEL_LOW>;
+		touchscreen-size-x = <1080>;
+		touchscreen-size-y = <2160>;
+		reset-gpios = <&tlmm 64 GPIO_ACTIVE_LOW>;
+	};
+};
+
 &pm8953_resin {
 	status = "okay";
 	linux,code = <KEY_VOLUMEDOWN>;
-- 
2.38.0

Re: [PATCH v4 3/3] arm64: dts: qcom: sdm632: fairphone-fp3: add touchscreen

[Krzysztof Kozlowski]

On 17/10/2022 06:04, Job Noorman wrote:
> Add Himax hx83112b touchscreen to the FP3 DT.
> 
> Signed-off-by: Job Noorman <job@noorman.info>


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v4 2/3] Input: add driver for Himax hx83112b touchscreen devices

[Jeff LaBundy]

Hi Job,

Great work so far, just a few remaining comments.

On Mon, Oct 17, 2022 at 12:04:07PM +0200, Job Noorman wrote:
> This patch adds support for Himax hx83112b touchscreen devices. As there
> are no publicly available data sheets for these devices, the
> implementation is based on the driver of the downstream Android kernel
> used in the Fairphone 3. This patch is a complete rewrite, though, and
> the code bears no resemblence to the original implementation.
> 
> The driver has been tested on the aforementioned phone.
> 
> Signed-off-by: Job Noorman <job@noorman.info>
> ---
>  MAINTAINERS                                |   1 +
>  drivers/input/touchscreen/Kconfig          |  11 +
>  drivers/input/touchscreen/Makefile         |   1 +
>  drivers/input/touchscreen/himax_hx83112b.c | 367 +++++++++++++++++++++
>  4 files changed, 380 insertions(+)
>  create mode 100644 drivers/input/touchscreen/himax_hx83112b.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2418bffe9187..51a03f9586f1 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9099,6 +9099,7 @@ M:	Job Noorman <job@noorman.info>
>  L:	linux-input@vger.kernel.org
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml
> +F:	drivers/input/touchscreen/himax_hx83112b.c
>  
>  HIPPI
>  M:	Jes Sorensen <jes@trained-monkey.org>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index dc90a3ea51ee..113b7dd7da2f 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -1379,4 +1379,15 @@ config TOUCHSCREEN_ZINITIX
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called zinitix.
>  
> +config TOUCHSCREEN_HIMAX_HX83112B
> +	tristate "Himax hx83112b touchscreen driver"
> +	depends on REGMAP_I2C

I think there was a misunderstanding here. You need to depend on I2C as
you did before, but additionally select REGMAP_I2C. See TSC2004 for one
such example.

> +	help
> +	  Say Y here to enable support for Himax hx83112b touchscreens.
> +
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called himax_hx83112b.
> +
>  endif
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 557f84fd2075..0f8bf79e01fe 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -116,3 +116,4 @@ obj-$(CONFIG_TOUCHSCREEN_ROHM_BU21023)	+= rohm_bu21023.o
>  obj-$(CONFIG_TOUCHSCREEN_RASPBERRYPI_FW)	+= raspberrypi-ts.o
>  obj-$(CONFIG_TOUCHSCREEN_IQS5XX)	+= iqs5xx.o
>  obj-$(CONFIG_TOUCHSCREEN_ZINITIX)	+= zinitix.o
> +obj-$(CONFIG_TOUCHSCREEN_HIMAX_HX83112B)	+= himax_hx83112b.o
> diff --git a/drivers/input/touchscreen/himax_hx83112b.c b/drivers/input/touchscreen/himax_hx83112b.c
> new file mode 100644
> index 000000000000..6f76fe48cfdd
> --- /dev/null
> +++ b/drivers/input/touchscreen/himax_hx83112b.c
> @@ -0,0 +1,367 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Driver for Himax hx83112b touchscreens
> + *
> + * Copyright (C) 2022 Job Noorman <job@noorman.info>
> + *
> + * This code is based on "Himax Android Driver Sample Code for QCT platform":
> + *
> + * Copyright (C) 2017 Himax Corporation.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.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/regmap.h>
> +
> +#define HIMAX_ID_83112B 0x83112b
> +
> +#define HIMAX_MAX_POINTS 10
> +

Nit: extraneous NL.

> +
> +#define HIMAX_REG_CFG_SET_ADDR	 0x00
> +#define HIMAX_REG_CFG_INIT_READ	 0x0c
> +#define HIMAX_REG_CFG_READ_VALUE 0x08
> +#define HIMAX_REG_READ_EVENT	 0x30
> +
> +#define HIMAX_CFG_PRODUCT_ID 0x900000d0
> +
> +#define HIMAX_INVALID_COORD 0xffff

As I mention, I personally find #defines easier to read when aligned.
However, I do not feel strongly about it.

> +
> +struct himax_event_point {
> +	__be16 x;
> +	__be16 y;
> +} __packed;
> +
> +struct himax_event {
> +	struct himax_event_point points[HIMAX_MAX_POINTS];
> +	u8 majors[HIMAX_MAX_POINTS];
> +	u8 pad0[2];
> +	u8 num_points;
> +	u8 pad1[2];
> +	u8 checksum_fix;
> +} __packed;
> +
> +static_assert(sizeof(struct himax_event) == 56);
> +
> +struct himax_ts_data {
> +	struct gpio_desc *gpiod_rst;
> +	struct input_dev *input_dev;
> +	struct i2c_client *client;
> +	struct regmap *regmap;
> +	struct touchscreen_properties props;
> +};
> +
> +static const struct regmap_config himax_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 32,
> +	.val_format_endian = REGMAP_ENDIAN_LITTLE,
> +};
> +
> +static int himax_read_config(struct himax_ts_data *ts, u32 address, u32 *dst)
> +{
> +	int error;
> +
> +	error = regmap_write(ts->regmap, HIMAX_REG_CFG_SET_ADDR, address);
> +	if (error)
> +		return error;
> +
> +	error = regmap_write(ts->regmap, HIMAX_REG_CFG_INIT_READ, 0x0);
> +	if (error)
> +		return error;
> +
> +	error = regmap_read(ts->regmap, HIMAX_REG_CFG_READ_VALUE, dst);
> +	if (error)
> +		return error;
> +
> +	return 0;
> +}
> +
> +static void himax_reset(struct himax_ts_data *ts)
> +{
> +	gpiod_set_value_cansleep(ts->gpiod_rst, 1);
> +
> +	/* Delay copied from downstream driver */
> +	msleep(20);
> +	gpiod_set_value_cansleep(ts->gpiod_rst, 0);
> +
> +	/*
> +	 * The downstream driver doesn't contain this delay but is seems safer
> +	 * to include it. The range is just a guess that seems to work well.
> +	 */
> +	usleep_range(1000, 1100);
> +}
> +
> +static int himax_read_product_id(struct himax_ts_data *ts, u32 *product_id)
> +{
> +	int error;
> +
> +	error = himax_read_config(ts, HIMAX_CFG_PRODUCT_ID, product_id);
> +	if (error)
> +		return error;
> +
> +	*product_id >>= 8;
> +	return 0;
> +}
> +
> +static int himax_check_product_id(struct himax_ts_data *ts)
> +{
> +	int error;
> +	u32 product_id;
> +
> +	error = himax_read_product_id(ts, &product_id);
> +	if (error)
> +		return error;
> +
> +	dev_dbg(&ts->client->dev, "Product id: %x\n", product_id);
> +
> +	switch (product_id) {
> +	case HIMAX_ID_83112B:
> +		return 0;
> +
> +	default:
> +		dev_err(&ts->client->dev,
> +			"Unknown product id: %x\n", product_id);
> +		return -EINVAL;
> +	}
> +}
> +
> +static int himax_input_register(struct himax_ts_data *ts)
> +{
> +	int error;
> +
> +	ts->input_dev = devm_input_allocate_device(&ts->client->dev);
> +	if (!ts->input_dev) {
> +		dev_err(&ts->client->dev, "Failed to allocate input device\n");
> +		return -ENOMEM;
> +	}
> +
> +	ts->input_dev->name = "Himax Touchscreen";
> +
> +	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_X);
> +	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_Y);
> +	input_set_abs_params(ts->input_dev, ABS_MT_WIDTH_MAJOR, 0, 200, 0, 0);
> +	input_set_abs_params(ts->input_dev, ABS_MT_TOUCH_MAJOR, 0, 200, 0, 0);
> +
> +	touchscreen_parse_properties(ts->input_dev, true, &ts->props);
> +
> +	error = input_mt_init_slots(ts->input_dev, HIMAX_MAX_POINTS,
> +				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
> +	if (error) {
> +		dev_err(&ts->client->dev,
> +			"Failed to initialize MT slots: %d\n", error);
> +		return error;
> +	}
> +
> +	error = input_register_device(ts->input_dev);
> +	if (error) {
> +		dev_err(&ts->client->dev,
> +			"Failed to register input device: %d\n", error);
> +		return error;
> +	}
> +
> +	return 0;
> +}
> +
> +static u8 himax_event_get_num_points(const struct himax_event *event)
> +{
> +	if (event->num_points == 0xff)
> +		return 0;
> +	else
> +		return event->num_points & 0x0f;
> +}
> +
> +static bool himax_process_event_point(struct himax_ts_data *ts,
> +				      const struct himax_event *event,
> +				      int point_index)
> +{
> +	const struct himax_event_point *point = &event->points[point_index];
> +	u16 x = be16_to_cpu(point->x);
> +	u16 y = be16_to_cpu(point->y);
> +	u8 w = event->majors[point_index];
> +
> +	if (x == HIMAX_INVALID_COORD || y == HIMAX_INVALID_COORD)
> +		return false;
> +
> +	input_mt_slot(ts->input_dev, point_index);
> +	input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER, true);
> +	touchscreen_report_pos(ts->input_dev, &ts->props, x, y, true);
> +	input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR, w);
> +	input_report_abs(ts->input_dev, ABS_MT_WIDTH_MAJOR, w);
> +	return true;
> +}
> +
> +static void himax_process_event(struct himax_ts_data *ts,
> +				const struct himax_event *event)
> +{
> +	int i;
> +	int num_points_left = himax_event_get_num_points(event);
> +
> +	for (i = 0; i < HIMAX_MAX_POINTS && num_points_left > 0; i++) {
> +		if (himax_process_event_point(ts, event, i))
> +			num_points_left--;
> +	}
> +
> +	input_mt_sync_frame(ts->input_dev);
> +	input_sync(ts->input_dev);
> +}
> +
> +static bool himax_verify_checksum(struct himax_ts_data *ts,
> +				  const struct himax_event *event)
> +{
> +	u8 *data = (u8 *)event;
> +	int i;
> +	u16 checksum = 0;
> +
> +	for (i = 0; i < sizeof(*event); i++)
> +		checksum += data[i];
> +
> +	if ((checksum & 0x00ff) != 0) {
> +		dev_err(&ts->client->dev, "Wrong event checksum: %04x\n",
> +			checksum);
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static int himax_handle_input(struct himax_ts_data *ts)
> +{
> +	int error;
> +	struct himax_event event;
> +
> +	error = regmap_raw_read(ts->regmap, HIMAX_REG_READ_EVENT, &event,
> +				sizeof(event));
> +	if (error) {
> +		dev_err(&ts->client->dev, "Failed to read input event: %d\n",
> +			error);
> +		return error;
> +	}
> +
> +	if (!himax_verify_checksum(ts, &event)) {
> +		/*
> +		 * We cannot process the current event when it has an invalid
> +		 * checksum but we don't consider this a fatal error.
> +		 */
> +		return 0;
> +	}
> +
> +	himax_process_event(ts, &event);
> +	return 0;

This seems a bit cleaner as:

        /* optional helpful comment */
        if (himax_verify_checksum(...))
                himax_process_event(...);

        return 0;

> +}
> +
> +static irqreturn_t himax_irq_handler(int irq, void *dev_id)
> +{
> +	struct himax_ts_data *ts = dev_id;
> +	int error = himax_handle_input(ts);

Similar to what was suggested elsewhere in the last revision:

        int error;

        error = himax_handle_input(...);

> +
> +	if (error)
> +		return IRQ_NONE;
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int himax_probe(struct i2c_client *client,
> +		       const struct i2c_device_id *id)
> +{
> +	int error;
> +	struct device *dev = &client->dev;
> +	struct himax_ts_data *ts;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +		dev_err(dev, "I2C check functionality failed\n");
> +		return -ENXIO;
> +	}
> +
> +	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, ts);
> +	ts->client = client;
> +
> +	ts->regmap = devm_regmap_init_i2c(client, &himax_regmap_config);
> +	error = PTR_ERR_OR_ZERO(ts->regmap);
> +	if (error) {
> +		dev_err(&client->dev,
> +			"Failed to initialize regmap: %d\n", error);
> +		return error;
> +	}
> +
> +	ts->gpiod_rst = devm_gpiod_get(&ts->client->dev, "reset",
> +				       GPIOD_OUT_HIGH);
> +	error = PTR_ERR_OR_ZERO(ts->gpiod_rst);
> +	if (error) {
> +		if (error != -EPROBE_DEFER)
> +			dev_err(&ts->client->dev,
> +				"Failed to get reset GPIO: %d\n", error);
> +		return error;
> +	}

This is just my $.02, but I do not think we need to conditionally
squelch the error message here.

> +
> +	himax_reset(ts);
> +
> +	error = himax_check_product_id(ts);
> +	if (error)
> +		return error;
> +
> +	error = himax_input_register(ts);
> +	if (error)
> +		return error;
> +
> +	return devm_request_threaded_irq(&client->dev, client->irq, NULL,
> +					 himax_irq_handler, IRQF_ONESHOT,
> +					 client->name, ts);
> +}
> +
> +static int himax_suspend(struct device *dev)
> +{
> +	struct himax_ts_data *ts = dev_get_drvdata(dev);
> +
> +	disable_irq(ts->client->irq);
> +	return 0;
> +}
> +
> +static int himax_resume(struct device *dev)
> +{
> +	struct himax_ts_data *ts = dev_get_drvdata(dev);
> +
> +	enable_irq(ts->client->irq);
> +	return 0;
> +}
> +
> +static DEFINE_SIMPLE_DEV_PM_OPS(himax_pm_ops, himax_suspend, himax_resume);
> +
> +static const struct i2c_device_id himax_ts_id[] = {
> +	{ "hx83112b", 0 },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(i2c, himax_ts_id);
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id himax_of_match[] = {
> +	{ .compatible = "himax,hx83112b" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, himax_of_match);
> +#endif
> +
> +static struct i2c_driver himax_ts_driver = {
> +	.probe = himax_probe,
> +	.id_table = himax_ts_id,
> +	.driver = {
> +		.name = "Himax-hx83112b-TS",
> +		.of_match_table = of_match_ptr(himax_of_match),
> +		.pm = pm_sleep_ptr(&himax_pm_ops),
> +	},
> +};
> +module_i2c_driver(himax_ts_driver);
> +
> +MODULE_AUTHOR("Job Noorman <job@noorman.info>");
> +MODULE_DESCRIPTION("Himax hx83112b touchscreen driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.38.0
> 

Kind regards,
Jeff LaBundy

Re: [PATCH v4 2/3] Input: add driver for Himax hx83112b touchscreen devices

[Job Noorman]

Hi Jeff,

On Sat Oct 22, 2022 at 6:25 AM CEST, Jeff LaBundy wrote:
> Hi Job,
>
> Great work so far, just a few remaining comments.

Thanks a lot for your second round of comments! Everything has been
addressed in v5.

Best regards,
Job