[PATCH 1/2] dt-bindings: input/touchscreen: add bindings for msg26xx

[PATCH 1/2] dt-bindings: input/touchscreen: add bindings for msg26xx

[Vincent Knecht]

This adds dts bindings for the mstar msg26xx touchscreen.

Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
---
 .../input/touchscreen/mstar,msg26xx.yaml      | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/mstar,msg26xx.yaml

diff --git a/Documentation/devicetree/bindings/input/touchscreen/mstar,msg26xx.yaml b/Documentation/devicetree/bindings/input/touchscreen/mstar,msg26xx.yaml
new file mode 100644
index 000000000000..50e1c8495cd6
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/mstar,msg26xx.yaml
@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/mstar,msg26xx.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: M-Star msg26xx touchscreen controller Bindings
+
+maintainers:
+  - Vincent Knecht <vincent.knecht@mailoo.org>
+
+allOf:
+  - $ref: touchscreen.yaml#
+
+properties:
+  compatible:
+    const: mstar,msg26xx
+
+  reg:
+    const: 0x26
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+
+  vdd-supply:
+    description: Power supply regulator for the chip
+
+  vddio-supply:
+    description: Power supply regulator for the I2C bus
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - reset-gpios
+  - touchscreen-size-x
+  - touchscreen-size-y
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      touchscreen@26 {
+        compatible = "mstar,msg26xx";
+        reg = <0x26>;
+        interrupt-parent = <&msmgpio>;
+        interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
+        reset-gpios = <&msmgpio 100 GPIO_ACTIVE_HIGH>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&ts_int_active>;
+        vdd-supply = <&pm8916_l17>;
+        vddio-supply = <&pm8916_l5>;
+        touchscreen-size-x = <720>;
+        touchscreen-size-y = <1280>;
+      };
+    };
+
+...
-- 
2.29.2

[PATCH 2/2] Input: add MStar msg26xx touchscreen driver

[Vincent Knecht]

Add support for the msg26xx touchscreen IC from MStar.
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>
---
 drivers/input/touchscreen/Kconfig   |  12 +
 drivers/input/touchscreen/Makefile  |   1 +
 drivers/input/touchscreen/msg26xx.c | 370 ++++++++++++++++++++++++++++
 3 files changed, 383 insertions(+)
 create mode 100644 drivers/input/touchscreen/msg26xx.c

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index f012fe746df0..bc4f604b4841 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -1334,4 +1334,16 @@ config TOUCHSCREEN_ZINITIX
 	  To compile this driver as a module, choose M here: the
 	  module will be called zinitix.
 
+config TOUCHSCREEN_MSG26XX
+	tristate "MStar msg26xx touchscreen support"
+	depends on I2C
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say Y here if you have an I2C touchscreen using MStar msg26xx.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called msg26xx.
+
 endif
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 6233541e9173..830ebf4973cb 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -112,3 +112,4 @@ 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_MSG26XX)	+= msg26xx.o
diff --git a/drivers/input/touchscreen/msg26xx.c b/drivers/input/touchscreen/msg26xx.c
new file mode 100644
index 000000000000..2e646cdca724
--- /dev/null
+++ b/drivers/input/touchscreen/msg26xx.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for MStar msg26xx 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.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/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#define MODE_DATA_RAW			0x5A
+
+#define TPD_WIDTH			2048
+#define TPD_HEIGHT			2048
+
+#define MAX_SUPPORTED_FINGER_NUM	5
+
+#define CHIP_ON_DELAY			15 // ms
+#define FIRMWARE_ON_DELAY		50 // ms
+
+struct point_coord {
+	u16	x;
+	u16	y;
+};
+
+struct packet {
+	u8	y_high : 4;
+	u8	x_high : 4;
+	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 msg26xx_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 int mstar_init_regulators(struct msg26xx_ts_data *msg26xx)
+{
+	struct i2c_client *client = msg26xx->client;
+	int error;
+
+	msg26xx->supplies[0].supply = "vdd";
+	msg26xx->supplies[1].supply = "vddio";
+	error = devm_regulator_bulk_get(&client->dev,
+					ARRAY_SIZE(msg26xx->supplies),
+					msg26xx->supplies);
+	if (error < 0) {
+		dev_err(&client->dev, "Failed to get regulators: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static void mstar_power_on(struct msg26xx_ts_data *msg26xx)
+{
+	gpiod_set_value(msg26xx->reset_gpiod, 0);
+	mdelay(10);
+	gpiod_set_value(msg26xx->reset_gpiod, 1);
+	mdelay(FIRMWARE_ON_DELAY);
+
+	enable_irq(msg26xx->client->irq);
+}
+
+static void mstar_report_finger(struct msg26xx_ts_data *msg26xx, int slot,
+				const struct point_coord *pc)
+{
+	input_mt_slot(msg26xx->input_dev, slot);
+	input_mt_report_slot_state(msg26xx->input_dev, MT_TOOL_FINGER, true);
+	touchscreen_report_pos(msg26xx->input_dev, &msg26xx->prop, pc->x, pc->y, true);
+	input_report_abs(msg26xx->input_dev, ABS_MT_TOUCH_MAJOR, 1);
+}
+
+static u8 mstar_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 mstar_ts_irq_handler(int irq, void *msg26xx_handler)
+{
+	struct msg26xx_ts_data *msg26xx = msg26xx_handler;
+	struct i2c_client *client = msg26xx->client;
+	struct touch_event touch_event;
+	struct point_coord coord;
+	struct i2c_msg msg[1];
+	struct packet *p;
+	u32 len;
+	int ret;
+	int i;
+
+	len = sizeof(struct touch_event);
+	memset(&touch_event, 0, len);
+
+	msg[0].addr = client->addr;
+	msg[0].flags = I2C_M_RD;
+	msg[0].len = len;
+	msg[0].buf = (u8 *)&touch_event;
+
+	ret = i2c_transfer(client->adapter, msg, 1);
+	if (ret != 1) {
+		dev_err(&client->dev, "Failed I2C transfer in irq handler!\n");
+		goto out;
+	}
+
+	if (touch_event.mode != MODE_DATA_RAW)
+		goto out;
+
+	if (mstar_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->x_high == 0xF && p->y_high == 0xF && p->x_low == 0xFF && p->y_low == 0xFF)
+			continue;
+
+		coord.x = ((p->x_high << 8) | p->x_low) * msg26xx->prop.max_x / TPD_WIDTH;
+		coord.y = ((p->y_high << 8) | p->y_low) * msg26xx->prop.max_y / TPD_HEIGHT;
+		mstar_report_finger(msg26xx, i, &coord);
+	}
+
+	input_mt_sync_frame(msg26xx->input_dev);
+	input_sync(msg26xx->input_dev);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static int mstar_start(struct msg26xx_ts_data *msg26xx)
+{
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(msg26xx->supplies),
+				      msg26xx->supplies);
+	if (error) {
+		dev_err(&msg26xx->client->dev,
+			"Failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	msleep(CHIP_ON_DELAY);
+
+	mstar_power_on(msg26xx);
+
+	return 0;
+}
+
+static int mstar_stop(struct msg26xx_ts_data *msg26xx)
+{
+	int error;
+
+	disable_irq(msg26xx->client->irq);
+
+	error = regulator_bulk_disable(ARRAY_SIZE(msg26xx->supplies),
+				       msg26xx->supplies);
+	if (error) {
+		dev_err(&msg26xx->client->dev,
+			"Failed to disable regulators: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int mstar_input_open(struct input_dev *dev)
+{
+	struct msg26xx_ts_data *msg26xx = input_get_drvdata(dev);
+
+	return mstar_start(msg26xx);
+}
+
+static void mstar_input_close(struct input_dev *dev)
+{
+	struct msg26xx_ts_data *msg26xx = input_get_drvdata(dev);
+
+	mstar_stop(msg26xx);
+}
+
+static int mstar_init_input_dev(struct msg26xx_ts_data *msg26xx)
+{
+	struct input_dev *input_dev;
+	int error;
+
+	input_dev = devm_input_allocate_device(&msg26xx->client->dev);
+	if (!input_dev) {
+		dev_err(&msg26xx->client->dev,
+			"Failed to allocate input device.");
+		return -ENOMEM;
+	}
+
+	input_set_drvdata(input_dev, msg26xx);
+	msg26xx->input_dev = input_dev;
+
+	input_dev->name = "MStar TouchScreen";
+	input_dev->phys = "input/ts";
+	input_dev->id.bustype = BUS_I2C;
+	input_dev->open = mstar_input_open;
+	input_dev->close = mstar_input_close;
+
+	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_WIDTH_MAJOR, 0, 15, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
+
+	touchscreen_parse_properties(input_dev, true, &msg26xx->prop);
+	if (!msg26xx->prop.max_x || !msg26xx->prop.max_y) {
+		dev_err(&msg26xx->client->dev,
+			"touchscreen-size-x and/or touchscreen-size-y not set in dts\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(&msg26xx->client->dev,
+			"Failed to initialize MT slots: %d", error);
+		return error;
+	}
+
+	error = input_register_device(input_dev);
+	if (error) {
+		dev_err(&msg26xx->client->dev,
+			"Failed to register input device: %d", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int mstar_ts_probe(struct i2c_client *client)
+{
+	struct msg26xx_ts_data *msg26xx;
+	int error;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev,
+			"Failed to assert adapter's support for plain I2C.\n");
+		return -ENXIO;
+	}
+
+	msg26xx = devm_kzalloc(&client->dev, sizeof(*msg26xx), GFP_KERNEL);
+	if (!msg26xx)
+		return -ENOMEM;
+
+	msg26xx->client = client;
+	i2c_set_clientdata(client, msg26xx);
+
+	error = mstar_init_regulators(msg26xx);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to initialize regulators: %d\n", error);
+		return error;
+	}
+
+	msg26xx->reset_gpiod = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(msg26xx->reset_gpiod)) {
+		error = PTR_ERR(msg26xx->reset_gpiod);
+		dev_err(&client->dev, "Failed to request reset GPIO: %d\n", error);
+		return error;
+	}
+
+	error = mstar_init_input_dev(msg26xx);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to initialize input device: %d\n", error);
+		return error;
+	}
+
+	irq_set_status_flags(client->irq, IRQ_NOAUTOEN);
+	error = devm_request_threaded_irq(&client->dev, client->irq,
+					  NULL, mstar_ts_irq_handler,
+					  IRQF_ONESHOT, client->name, msg26xx);
+	if (error) {
+		dev_err(&client->dev, "Failed to request IRQ: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int __maybe_unused mstar_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct msg26xx_ts_data *msg26xx = i2c_get_clientdata(client);
+
+	mutex_lock(&msg26xx->input_dev->mutex);
+
+	if (input_device_enabled(msg26xx->input_dev))
+		mstar_stop(msg26xx);
+
+	mutex_unlock(&msg26xx->input_dev->mutex);
+
+	return 0;
+}
+
+static int __maybe_unused mstar_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct msg26xx_ts_data *msg26xx = i2c_get_clientdata(client);
+	int ret = 0;
+
+	mutex_lock(&msg26xx->input_dev->mutex);
+
+	if (input_device_enabled(msg26xx->input_dev))
+		ret = mstar_start(msg26xx);
+
+	mutex_unlock(&msg26xx->input_dev->mutex);
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(mstar_pm_ops, mstar_suspend, mstar_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id mstar_of_match[] = {
+	{ .compatible = "mstar,msg26xx" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mstar_of_match);
+#endif
+
+static struct i2c_driver mstar_ts_driver = {
+	.probe_new = mstar_ts_probe,
+	.driver = {
+		.name = "MStar-TS",
+		.pm = &mstar_pm_ops,
+		.of_match_table = of_match_ptr(mstar_of_match),
+	},
+};
+module_i2c_driver(mstar_ts_driver);
+
+MODULE_AUTHOR("Vincent Knecht <vincent.knecht@mailoo.org>");
+MODULE_DESCRIPTION("MStar touchscreen driver");
+MODULE_LICENSE("GPL v2");
-- 
2.29.2

Re: [PATCH 2/2] Input: add MStar msg26xx touchscreen driver

[Dmitry Torokhov]

Hi Vincent,

On Wed, Jan 20, 2021 at 07:01:08PM +0100, Vincent Knecht wrote:
> +struct packet {
> +	u8	y_high : 4;
> +	u8	x_high : 4;

This will not work on big endian devices as order of bitfields changes.
I'd recommended treating contact packet as sequence of bytes and parse,
i.e.

	x = ((buf[0] & 0x0f) << 8) | buf[1];
	x = ((buf[0] & 0xf0) << 4) | buf[2];
	...

> +	u8	x_low;
> +	u8	y_low;
> +	u8	pressure;
> +};
> +
> +
> +static void mstar_power_on(struct msg26xx_ts_data *msg26xx)
> +{
> +	gpiod_set_value(msg26xx->reset_gpiod, 0);
> +	mdelay(10);
> +	gpiod_set_value(msg26xx->reset_gpiod, 1);
> +	mdelay(FIRMWARE_ON_DELAY);

I am pretty sure this is incorrect. You are saying that you release the
reset line, wait a bit, and then assert it. gpiod is a logical API, with
0 being inactive and 1 being active, and here you want to activate the
reset line, wait appropriate time, release it, and wait for the device
to initialize. What does the datasheet say about reset GPIO polarity?

Thanks.

-- 
Dmitry

Re: [PATCH 2/2] Input: add MStar msg26xx touchscreen driver

[Vincent Knecht]

Hi Dmitry!

Le mercredi 20 janvier 2021 à 23:03 -0800, Dmitry Torokhov a écrit :
> Hi Vincent,
> 
> On Wed, Jan 20, 2021 at 07:01:08PM +0100, Vincent Knecht wrote:
> > +struct packet {
> > +       u8      y_high : 4;
> > +       u8      x_high : 4;
> 
> This will not work on big endian devices as order of bitfields changes.
> I'd recommended treating contact packet as sequence of bytes and parse,
> i.e.
> 
>         x = ((buf[0] & 0x0f) << 8) | buf[1];
>         x = ((buf[0] & 0xf0) << 4) | buf[2];
>         ...

Ok, will change in v2

> > +       u8      x_low;
> > +       u8      y_low;
> > +       u8      pressure;
> > +};
> > +
> > +
> > +static void mstar_power_on(struct msg26xx_ts_data *msg26xx)
> > +{
> > +       gpiod_set_value(msg26xx->reset_gpiod, 0);
> > +       mdelay(10);
> > +       gpiod_set_value(msg26xx->reset_gpiod, 1);
> > +       mdelay(FIRMWARE_ON_DELAY);
> 
> I am pretty sure this is incorrect. You are saying that you release the
> reset line, wait a bit, and then assert it. gpiod is a logical API, with
> 0 being inactive and 1 being active, and here you want to activate the
> reset line, wait appropriate time, release it, and wait for the device
> to initialize. What does the datasheet say about reset GPIO polarity?
> 
> Thanks.

I don't have any datasheet, only downstream code and dts for my device...
After changing this function to assert then deassert and also the reset gpio
polarity in my dts, it works as intended.
I'll send a v2 shortly, also changing the example section in bindings to
reflect the dts change I had to make (plus a minor change in title).

Thank you for the review!