Add Hynitron cstxxx Touchscreen

From: Chris Morgan <[email protected]>

Add support for the Hynitron cst3xx controller found on devices such as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver was built from sources provided by Hynitron to Anbernic (possibly via Rockchip as an intermediary) and marked as GPLv2 in the code. This driver was written strictly for the cst3xx series, but in most places was left somewhat generic so support could be easily added to other devices in the future.

Signed-off-by Chris Morgan <[email protected]>

---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/hynitron_cstxxx.c | 508 ++++++++++++++++++++
 3 files changed, 521 insertions(+)
 create mode 100644 drivers/input/touchscreen/hynitron_cstxxx.c

drivers/input/touchscreen/Kconfig +0 -0

index 2d70c945b20a..9a9528e59c36 100644

drivers/input/touchscreen/Kconfig +9 -0

+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile +1 -0

index 557f84fd2075..43860ca19b98 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o

drivers/input/touchscreen/hynitron_cstxxx.c new file +134 -0

new file mode 100644
index 000000000000..11701ff39eb1
@@ -0,0 +1,508 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Driver for Hynitron cstxxx Touchscreen
+ *
+ *  Copyright (c) 2022 Chris Morgan <[email protected]>
+ *
+ *  This code is based on hynitron_core.c authored by Hynitron.
+ *  Note that no datasheet was available, so much of these registers
+ *  are undocumented. This is essentially a cleaned-up version of the
+ *  vendor driver with support removed for hardware I cannot test and
+ *  device-specific functions replated with generic functions wherever
+ *  possible.
+ */
+
+#include <asm/unaligned.h>
+#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/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Per chip data */
+struct hynitron_ts_chip_data {
+	unsigned int max_touch_num;
+	u32 ic_chkcode;
+	int (*firmware_info)(struct i2c_client *client);
+	int (*bootloader_enter)(struct i2c_client *client);
+	int (*init_input)(struct i2c_client *client);
+	void (*report_touch)(struct i2c_client *client);
+};
+
+/* Data generic to all (supported and non-supported) controllers. */
+struct hynitron_ts_data {
+	const struct hynitron_ts_chip_data *pdata;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *irq_gpio;
+};
+
+/*
+ * Since I have no datasheet, these values are guessed and/or assumed
+ * based on observation and testing.
+ */
+#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
+#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
+#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
+#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
+#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
+
+#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
+#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
+#define CST3XX_BOOTLDR_CHK_VAL			0xac
+
+#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
+#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
+#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
+#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
+#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
+#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
+
+
+/*
+ * Hard coded reset delay value of 20ms not IC dependent in
+ * vendor driver.
+ */
+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);
+}
+
+static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	ts_data->pdata->report_touch(client);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The vendor driver would retry twice before failing to read or write
+ * to the i2c device.
+ */
+
+static int cst3xx_i2c_write(struct i2c_client *client,
+			    unsigned char *buf, int len)
+{
+	int ret;
+	int retries = 0;
+
+	while (retries < 2) {
+		ret = i2c_master_send(client, buf, len);
+		if (ret == len)
+			return 0;
+		if (ret <= 0)
+			retries++;
+		else
+			break;
+	}
+
+	return ret < 0 ? ret : -EIO;
+}
+
+static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
+				    u8 *val, u16 len)
+{
+	__le16 buf = cpu_to_le16(reg);
+	struct i2c_msg msgs[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 2,
+			.buf = (u8 *)&buf,
+		},
+		{
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = len,
+			.buf = val,
+		}
+	};

drivers/input/touchscreen/hynitron_cstxxx.c new file +23 -0

+
+	return ret;
+}
+
+static int cst3xx_firmware_info(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int ret;
+	u32 tmp;
+	unsigned char buf[4];
+
+	/*
+	 * Tests suggest this command needed to read firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_START_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(10);
+
+	/*
+	 * Read register for check-code to determine if device detected

drivers/input/touchscreen/hynitron_cstxxx.c new file +124 -0

+		return -ENODEV;
+	}
+
+	mdelay(10);
+
+	/* Read firmware version and test if firmware missing. */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_VERSION_REG,
+				       buf, 4);
+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if (tmp == CST3XX_FIRMWARE_VER_INVALID_VAL) {
+		dev_err(&client->dev, "Device firmware missing\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Tests suggest cmd required to exit reading firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_END_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(5);
+
+	return 0;
+}
+
+static int cst3xx_bootloader_enter(struct i2c_client *client)
+{
+	int ret;
+	u8 retry;
+	u32 tmp;
+	unsigned char buf[3];
+
+	for (retry = 0; retry < 5; retry++) {
+		hyn_reset_proc(client, (7 + retry));
+		/* set cmd to enter program mode */
+		put_unaligned_le24(CST3XX_BOOTLDR_PROG_CMD, buf);
+		ret = cst3xx_i2c_write(client, buf, 3);
+		if (ret < 0)
+			continue;
+		mdelay(2);
+
+		/* check whether in program mode */
+		ret = cst3xx_i2c_read_register(client,
+					       CST3XX_BOOTLDR_PROG_CHK_REG,
+					       buf, 1);
+		tmp = get_unaligned(buf);
+
+		if (ret < 0)
+			continue;
+
+		if (tmp == CST3XX_BOOTLDR_CHK_VAL)
+			break;
+	}
+
+	if (tmp != CST3XX_BOOTLDR_CHK_VAL) {
+		dev_err(&client->dev, "%s unable to enter bootloader mode\n",
+			__func__);
+		return -ENODEV;
+	}
+
+	hyn_reset_proc(client, 40);
+
+	return 0;
+}
+
+static void cst3xx_touch_update(struct hynitron_ts_data *ts_data,
+				s32 id, s32 x, s32 y, s32 w)
+{
+	input_mt_slot(ts_data->input_dev, id);
+	input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, 1);
+	touchscreen_report_pos(ts_data->input_dev, &ts_data->prop, x, y, true);
+	input_report_abs(ts_data->input_dev, ABS_MT_TOUCH_MAJOR, w);
+}
+
+static int cst3xx_finish_touch_read(struct i2c_client *client)
+{
+	unsigned char buf[3];
+	int err;
+
+	put_unaligned_le24(CST3XX_TOUCH_DATA_STOP_CMD, buf);
+	err = cst3xx_i2c_write(client, buf, 3);
+	if (err < 0) {
+		dev_err(&client->dev, "send read touch info ending failed.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+/*
+ * Handle events from IRQ. Note that for cst3xx it appears that IRQ
+ * fires continuously while touched, otherwise once every 1500ms
+ * when not touched (assume touchscreen waking up periodically).
+ * Note buffer is sized for 5 fingers, if more needed buffer must
+ * be increased. The buffer contains 5 bytes for each touch point,
+ * a touch count byte, a check byte, and then a second check byte after
+ * all other touch points.
+ *
+ * For example 1 touch would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]
+ *
+ * 3 touches would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]:touch2[5]:touch3[5]:chk_byte[1]
+ */
+static void cst3xx_touch_report(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	unsigned char buf[28];
+	unsigned char finger_id, sw;
+	unsigned int input_x = 0;
+	unsigned int input_y = 0;
+	unsigned int input_w = 0;
+	int idx = 0;
+	int i, err;
+	int touch_cnt, end_byte;
+
+	/* Read and validate the first bits of input data. */
+	err = cst3xx_i2c_read_register(client, CST3XX_TOUCH_DATA_PART_REG,
+				       buf, 28);

drivers/input/touchscreen/hynitron_cstxxx.c new file +197 -0

+		return;
+	}
+
+	touch_cnt = buf[5] & CST3XX_TOUCH_COUNT_MASK;
+
+	/* If no touches registered, clear the input slots. */
+	if (touch_cnt == 0) {
+		input_mt_sync_frame(ts_data->input_dev);
+		input_sync(ts_data->input_dev);
+		return;
+	}
+
+	/*
+	 * Check the check bit of the last touch slot. The check bit is
+	 * always present after touch point 1 for valid data, and then
+	 * appears as the last byte after all other touch data.
+	 */
+	if (touch_cnt > 1) {
+		end_byte = touch_cnt * 5 + 2;
+		if (buf[end_byte] != CST3XX_TOUCH_DATA_CHK_VAL) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			return;
+		}
+	}
+
+	/* Parse through the buffer to capture touch data. */
+	for (i = 0; i < touch_cnt; i++) {
+		input_x = ((buf[idx + 1] << 4) | ((buf[idx + 3] >> 4) & 0x0f));
+		input_y = ((buf[idx + 2] << 4) | (buf[idx + 3] & 0x0f));
+		input_w = (buf[idx + 4] >> 3);
+		sw = (buf[idx] & 0x0f) >> 1;
+		finger_id = (buf[idx] >> 4) & 0x0f;
+
+		/* Sanity check we don't have more fingers than we expect */
+		if (ts_data->pdata->max_touch_num < finger_id) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			break;
+		}
+
+		/* sw value of 0 means no touch, 0x03 means touch */
+		if (sw == CST3XX_TOUCH_DATA_TOUCH_VAL)
+			cst3xx_touch_update(ts_data, finger_id,
+					    input_x, input_y, input_w);
+
+		idx += 5;
+
+		/* Skip the 2 bits between point 1 and point 2 */
+		if (i == 0)
+			idx += 2;
+	}
+
+	input_mt_sync_frame(ts_data->input_dev);
+	input_sync(ts_data->input_dev);
+}
+
+static int cst3xx_input_dev_int(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int err;
+
+	ts_data->input_dev = devm_input_allocate_device(&ts_data->client->dev);
+	if (!ts_data->input_dev) {
+		dev_err(&ts_data->client->dev,
+			"Failed to allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	ts_data->input_dev->name = "Hynitron cst3xx Touchscreen";
+	ts_data->input_dev->phys = "input/ts";
+	ts_data->input_dev->id.bustype = BUS_I2C;
+
+	input_set_drvdata(ts_data->input_dev, ts_data);
+
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(ts_data->input_dev, ABS_MT_TOUCH_MAJOR,
+			     0, 255, 0, 0);
+
+	touchscreen_parse_properties(ts_data->input_dev, true, &ts_data->prop);
+
+	if (!ts_data->prop.max_x || !ts_data->prop.max_y) {
+		dev_err(&client->dev,
+			"Invalid x/y (%d, %d), using defaults\n",
+			ts_data->prop.max_x, ts_data->prop.max_y);
+		ts_data->prop.max_x = 1152;
+		ts_data->prop.max_y = 1920;
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_X, ts_data->prop.max_x);
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_Y, ts_data->prop.max_y);
+	}
+
+	err = input_mt_init_slots(ts_data->input_dev,
+				  ts_data->pdata->max_touch_num,
+				  INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	err = input_register_device(ts_data->input_dev);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int hyn_probe(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data;
+	int err;
+
+	ts_data = devm_kzalloc(&client->dev, sizeof(*ts_data), GFP_KERNEL);
+	if (!ts_data)
+		return -ENOMEM;
+
+	ts_data->client = client;
+	i2c_set_clientdata(client, ts_data);
+
+	ts_data->reset_gpio = devm_gpiod_get(&client->dev,
+					     "reset", GPIOD_OUT_LOW);
+	err = PTR_ERR_OR_ZERO(ts_data->reset_gpio);
+	if (err < 0) {
+		dev_err(&client->dev, "request reset gpio failed: %d\n", err);
+		return err;
+	}
+
+	ts_data->pdata = of_device_get_match_data(&client->dev);
+	if (!ts_data->pdata)
+		return -EINVAL;
+
+	hyn_reset_proc(client, 60);
+
+	err = ts_data->pdata->bootloader_enter(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->init_input(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->firmware_info(client);
+	if (err < 0)
+		return err;
+
+	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					hyn_interrupt_handler,
+					IRQF_ONESHOT,
+					"Hynitron Touch Int", client);
+	if (err < 0) {
+		dev_err(&client->dev, "failed to request IRQ\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct hynitron_ts_chip_data cst3xx_data = {
+	.max_touch_num		= 5,
+	.ic_chkcode		= 0xcaca0000,
+	.firmware_info		= &cst3xx_firmware_info,
+	.bootloader_enter	= &cst3xx_bootloader_enter,
+	.init_input		= &cst3xx_input_dev_int,
+	.report_touch		= &cst3xx_touch_report,
+};
+
+static const struct i2c_device_id hyn_tpd_id[] = {
+	{ .name = "hynitron_ts", 0 },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
+
+static const struct of_device_id hyn_dt_match[] = {
+	{ .compatible = "hynitron,cst340", .data = &cst3xx_data },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, hyn_dt_match);
+
+static struct i2c_driver hynitron_i2c_driver = {
+	.driver = {
+		.name = "Hynitron-TS",
+		.of_match_table = of_match_ptr(hyn_dt_match),
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table = hyn_tpd_id,
+	.probe_new = hyn_probe,
+};
+
+module_i2c_driver(hynitron_i2c_driver);
+
+MODULE_AUTHOR("Chris Morgan");
+MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
+MODULE_LICENSE("GPL");

Signature · 1 line

2.25.1

Hi Chris,

Thank you for your patch.

Quoted 26 lines · Chris Morgan

From: Chris Morgan <[email protected]>

Add support for the Hynitron cst3xx controller found on devices such as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver was built from sources provided by Hynitron to Anbernic (possibly via Rockchip as an intermediary) and marked as GPLv2 in the code. This driver was written strictly for the cst3xx series, but in most places was left somewhat generic so support could be easily added to other devices in the future.

Signed-off-by Chris Morgan <[email protected]>

---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/hynitron_cstxxx.c | 508 ++++++++++++++++++++
 3 files changed, 521 insertions(+)
 create mode 100644 drivers/input/touchscreen/hynitron_cstxxx.c

drivers/input/touchscreen/Kconfig +0 -0

index 2d70c945b20a..9a9528e59c36 100644
@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 

drivers/input/touchscreen/Kconfig config TOUCHSCREEN_HYCON_HY46XX · line 427

Quoted 3 lines

drivers/input/touchscreen/Kconfig +3 -0

+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C

Since we include linux/of.h, I think we should also add:
depends on OF

There are some small nitpicks below as well.

With those addressed, please add:

Reviewed-by Mattijs Korpershoek <[email protected]>

Quoted 164 lines

drivers/input/touchscreen/Kconfig +9 -0

+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile +1 -0

index 557f84fd2075..43860ca19b98 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o

drivers/input/touchscreen/hynitron_cstxxx.c new file +134 -0

new file mode 100644
index 000000000000..11701ff39eb1
@@ -0,0 +1,508 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Driver for Hynitron cstxxx Touchscreen
+ *
+ *  Copyright (c) 2022 Chris Morgan <[email protected]>
+ *
+ *  This code is based on hynitron_core.c authored by Hynitron.
+ *  Note that no datasheet was available, so much of these registers
+ *  are undocumented. This is essentially a cleaned-up version of the
+ *  vendor driver with support removed for hardware I cannot test and
+ *  device-specific functions replated with generic functions wherever
+ *  possible.
+ */
+
+#include <asm/unaligned.h>
+#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/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Per chip data */
+struct hynitron_ts_chip_data {
+	unsigned int max_touch_num;
+	u32 ic_chkcode;
+	int (*firmware_info)(struct i2c_client *client);
+	int (*bootloader_enter)(struct i2c_client *client);
+	int (*init_input)(struct i2c_client *client);
+	void (*report_touch)(struct i2c_client *client);
+};
+
+/* Data generic to all (supported and non-supported) controllers. */
+struct hynitron_ts_data {
+	const struct hynitron_ts_chip_data *pdata;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *irq_gpio;
+};
+
+/*
+ * Since I have no datasheet, these values are guessed and/or assumed
+ * based on observation and testing.
+ */
+#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
+#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
+#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
+#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
+#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
+
+#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
+#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
+#define CST3XX_BOOTLDR_CHK_VAL			0xac
+
+#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
+#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
+#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
+#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
+#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
+#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
+
+
+/*
+ * Hard coded reset delay value of 20ms not IC dependent in
+ * vendor driver.
+ */
+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);
+}
+
+static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	ts_data->pdata->report_touch(client);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The vendor driver would retry twice before failing to read or write
+ * to the i2c device.
+ */
+
+static int cst3xx_i2c_write(struct i2c_client *client,
+			    unsigned char *buf, int len)
+{
+	int ret;
+	int retries = 0;
+
+	while (retries < 2) {
+		ret = i2c_master_send(client, buf, len);
+		if (ret == len)
+			return 0;
+		if (ret <= 0)
+			retries++;
+		else
+			break;
+	}
+
+	return ret < 0 ? ret : -EIO;
+}
+
+static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
+				    u8 *val, u16 len)
+{
+	__le16 buf = cpu_to_le16(reg);
+	struct i2c_msg msgs[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 2,
+			.buf = (u8 *)&buf,
+		},
+		{
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = len,
+			.buf = val,
+		}
+	};

drivers/input/touchscreen/hynitron_cstxxx.c line 144

Quoted 10 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +10 -0

+	int ret;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret >= 0)
+		ret = (ret == ARRAY_SIZE(msgs) ? 0 : -EIO);
+
+	if (ret)
+		dev_err(&client->dev,
+			"Error reading %d bytes from 0x%04x: %d\n",
+			len, reg, ret);

This could be a single line, since column limit is 100chars now. This applies for a lot of other wrapped lines in this file.

Please consider joining such lines to reduce the overall line count.

Quoted 28 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +27 -0

+
+	return ret;
+}
+
+static int cst3xx_firmware_info(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int ret;
+	u32 tmp;
+	unsigned char buf[4];
+
+	/*
+	 * Tests suggest this command needed to read firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_START_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(10);
+
+	/*
+	 * Read register for check-code to determine if device detected
+	 * correctly.
+	 */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_CHK_CODE_REG,
+				       buf, 4);

drivers/input/touchscreen/hynitron_cstxxx.c line 177

Quoted 6 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +6 -0

+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if ((tmp & 0xffff0000) != ts_data->pdata->ic_chkcode) {
+		dev_err(&client->dev, "%s ic mismatch\n", __func__);

Should we print the device's ic_chkcode in case we don't recognize it?

Quoted 129 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +129 -0

+		return -ENODEV;
+	}
+
+	mdelay(10);
+
+	/* Read firmware version and test if firmware missing. */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_VERSION_REG,
+				       buf, 4);
+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if (tmp == CST3XX_FIRMWARE_VER_INVALID_VAL) {
+		dev_err(&client->dev, "Device firmware missing\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Tests suggest cmd required to exit reading firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_END_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(5);
+
+	return 0;
+}
+
+static int cst3xx_bootloader_enter(struct i2c_client *client)
+{
+	int ret;
+	u8 retry;
+	u32 tmp;
+	unsigned char buf[3];
+
+	for (retry = 0; retry < 5; retry++) {
+		hyn_reset_proc(client, (7 + retry));
+		/* set cmd to enter program mode */
+		put_unaligned_le24(CST3XX_BOOTLDR_PROG_CMD, buf);
+		ret = cst3xx_i2c_write(client, buf, 3);
+		if (ret < 0)
+			continue;
+		mdelay(2);
+
+		/* check whether in program mode */
+		ret = cst3xx_i2c_read_register(client,
+					       CST3XX_BOOTLDR_PROG_CHK_REG,
+					       buf, 1);
+		tmp = get_unaligned(buf);
+
+		if (ret < 0)
+			continue;
+
+		if (tmp == CST3XX_BOOTLDR_CHK_VAL)
+			break;
+	}
+
+	if (tmp != CST3XX_BOOTLDR_CHK_VAL) {
+		dev_err(&client->dev, "%s unable to enter bootloader mode\n",
+			__func__);
+		return -ENODEV;
+	}
+
+	hyn_reset_proc(client, 40);
+
+	return 0;
+}
+
+static void cst3xx_touch_update(struct hynitron_ts_data *ts_data,
+				s32 id, s32 x, s32 y, s32 w)
+{
+	input_mt_slot(ts_data->input_dev, id);
+	input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, 1);
+	touchscreen_report_pos(ts_data->input_dev, &ts_data->prop, x, y, true);
+	input_report_abs(ts_data->input_dev, ABS_MT_TOUCH_MAJOR, w);
+}
+
+static int cst3xx_finish_touch_read(struct i2c_client *client)
+{
+	unsigned char buf[3];
+	int err;
+
+	put_unaligned_le24(CST3XX_TOUCH_DATA_STOP_CMD, buf);
+	err = cst3xx_i2c_write(client, buf, 3);
+	if (err < 0) {
+		dev_err(&client->dev, "send read touch info ending failed.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+/*
+ * Handle events from IRQ. Note that for cst3xx it appears that IRQ
+ * fires continuously while touched, otherwise once every 1500ms
+ * when not touched (assume touchscreen waking up periodically).
+ * Note buffer is sized for 5 fingers, if more needed buffer must
+ * be increased. The buffer contains 5 bytes for each touch point,
+ * a touch count byte, a check byte, and then a second check byte after
+ * all other touch points.
+ *
+ * For example 1 touch would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]
+ *
+ * 3 touches would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]:touch2[5]:touch3[5]:chk_byte[1]
+ */
+static void cst3xx_touch_report(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	unsigned char buf[28];
+	unsigned char finger_id, sw;
+	unsigned int input_x = 0;
+	unsigned int input_y = 0;
+	unsigned int input_w = 0;
+	int idx = 0;
+	int i, err;
+	int touch_cnt, end_byte;
+
+	/* Read and validate the first bits of input data. */
+	err = cst3xx_i2c_read_register(client, CST3XX_TOUCH_DATA_PART_REG,
+				       buf, 28);
+	if ((err < 0) || (buf[6] != CST3XX_TOUCH_DATA_CHK_VAL) ||
+	    (buf[0] == CST3XX_TOUCH_DATA_CHK_VAL)) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");
+		return;
+	}

drivers/input/touchscreen/hynitron_cstxxx.c line 311

Quoted 5 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +5 -0

+
+	/* Report to the device we're done reading the touch data. */
+	err = cst3xx_finish_touch_read(client);
+	if (err < 0) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");

We are already printing in cst3xx_finish_touch_read(), no need to print here again.

Quoted 200 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +197 -0

+		return;
+	}
+
+	touch_cnt = buf[5] & CST3XX_TOUCH_COUNT_MASK;
+
+	/* If no touches registered, clear the input slots. */
+	if (touch_cnt == 0) {
+		input_mt_sync_frame(ts_data->input_dev);
+		input_sync(ts_data->input_dev);
+		return;
+	}
+
+	/*
+	 * Check the check bit of the last touch slot. The check bit is
+	 * always present after touch point 1 for valid data, and then
+	 * appears as the last byte after all other touch data.
+	 */
+	if (touch_cnt > 1) {
+		end_byte = touch_cnt * 5 + 2;
+		if (buf[end_byte] != CST3XX_TOUCH_DATA_CHK_VAL) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			return;
+		}
+	}
+
+	/* Parse through the buffer to capture touch data. */
+	for (i = 0; i < touch_cnt; i++) {
+		input_x = ((buf[idx + 1] << 4) | ((buf[idx + 3] >> 4) & 0x0f));
+		input_y = ((buf[idx + 2] << 4) | (buf[idx + 3] & 0x0f));
+		input_w = (buf[idx + 4] >> 3);
+		sw = (buf[idx] & 0x0f) >> 1;
+		finger_id = (buf[idx] >> 4) & 0x0f;
+
+		/* Sanity check we don't have more fingers than we expect */
+		if (ts_data->pdata->max_touch_num < finger_id) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			break;
+		}
+
+		/* sw value of 0 means no touch, 0x03 means touch */
+		if (sw == CST3XX_TOUCH_DATA_TOUCH_VAL)
+			cst3xx_touch_update(ts_data, finger_id,
+					    input_x, input_y, input_w);
+
+		idx += 5;
+
+		/* Skip the 2 bits between point 1 and point 2 */
+		if (i == 0)
+			idx += 2;
+	}
+
+	input_mt_sync_frame(ts_data->input_dev);
+	input_sync(ts_data->input_dev);
+}
+
+static int cst3xx_input_dev_int(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int err;
+
+	ts_data->input_dev = devm_input_allocate_device(&ts_data->client->dev);
+	if (!ts_data->input_dev) {
+		dev_err(&ts_data->client->dev,
+			"Failed to allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	ts_data->input_dev->name = "Hynitron cst3xx Touchscreen";
+	ts_data->input_dev->phys = "input/ts";
+	ts_data->input_dev->id.bustype = BUS_I2C;
+
+	input_set_drvdata(ts_data->input_dev, ts_data);
+
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(ts_data->input_dev, ABS_MT_TOUCH_MAJOR,
+			     0, 255, 0, 0);
+
+	touchscreen_parse_properties(ts_data->input_dev, true, &ts_data->prop);
+
+	if (!ts_data->prop.max_x || !ts_data->prop.max_y) {
+		dev_err(&client->dev,
+			"Invalid x/y (%d, %d), using defaults\n",
+			ts_data->prop.max_x, ts_data->prop.max_y);
+		ts_data->prop.max_x = 1152;
+		ts_data->prop.max_y = 1920;
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_X, ts_data->prop.max_x);
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_Y, ts_data->prop.max_y);
+	}
+
+	err = input_mt_init_slots(ts_data->input_dev,
+				  ts_data->pdata->max_touch_num,
+				  INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	err = input_register_device(ts_data->input_dev);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int hyn_probe(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data;
+	int err;
+
+	ts_data = devm_kzalloc(&client->dev, sizeof(*ts_data), GFP_KERNEL);
+	if (!ts_data)
+		return -ENOMEM;
+
+	ts_data->client = client;
+	i2c_set_clientdata(client, ts_data);
+
+	ts_data->reset_gpio = devm_gpiod_get(&client->dev,
+					     "reset", GPIOD_OUT_LOW);
+	err = PTR_ERR_OR_ZERO(ts_data->reset_gpio);
+	if (err < 0) {
+		dev_err(&client->dev, "request reset gpio failed: %d\n", err);
+		return err;
+	}
+
+	ts_data->pdata = of_device_get_match_data(&client->dev);
+	if (!ts_data->pdata)
+		return -EINVAL;
+
+	hyn_reset_proc(client, 60);
+
+	err = ts_data->pdata->bootloader_enter(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->init_input(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->firmware_info(client);
+	if (err < 0)
+		return err;
+
+	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					hyn_interrupt_handler,
+					IRQF_ONESHOT,
+					"Hynitron Touch Int", client);
+	if (err < 0) {
+		dev_err(&client->dev, "failed to request IRQ\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct hynitron_ts_chip_data cst3xx_data = {
+	.max_touch_num		= 5,
+	.ic_chkcode		= 0xcaca0000,
+	.firmware_info		= &cst3xx_firmware_info,
+	.bootloader_enter	= &cst3xx_bootloader_enter,
+	.init_input		= &cst3xx_input_dev_int,
+	.report_touch		= &cst3xx_touch_report,
+};
+
+static const struct i2c_device_id hyn_tpd_id[] = {
+	{ .name = "hynitron_ts", 0 },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
+
+static const struct of_device_id hyn_dt_match[] = {
+	{ .compatible = "hynitron,cst340", .data = &cst3xx_data },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, hyn_dt_match);
+
+static struct i2c_driver hynitron_i2c_driver = {
+	.driver = {
+		.name = "Hynitron-TS",
+		.of_match_table = of_match_ptr(hyn_dt_match),
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table = hyn_tpd_id,
+	.probe_new = hyn_probe,
+};
+
+module_i2c_driver(hynitron_i2c_driver);
+
+MODULE_AUTHOR("Chris Morgan");
+MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
+MODULE_LICENSE("GPL");

Signature · 1 line

2.25.1

Quoted 32 lines · Mattijs Korpershoek

Hi Chris,

Thank you for your patch.

Quoted 26 lines · Chris Morgan

From: Chris Morgan <[email protected]>

Add support for the Hynitron cst3xx controller found on devices such as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver was built from sources provided by Hynitron to Anbernic (possibly via Rockchip as an intermediary) and marked as GPLv2 in the code. This driver was written strictly for the cst3xx series, but in most places was left somewhat generic so support could be easily added to other devices in the future.

Signed-off-by Chris Morgan <[email protected]>

---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/hynitron_cstxxx.c | 508 ++++++++++++++++++++
 3 files changed, 521 insertions(+)
 create mode 100644 drivers/input/touchscreen/hynitron_cstxxx.c

drivers/input/touchscreen/Kconfig +0 -0

index 2d70c945b20a..9a9528e59c36 100644
@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 

Quoted 6 lines

drivers/input/touchscreen/Kconfig config TOUCHSCREEN_HYCON_HY46XX · line 427

Quoted 3 lines

drivers/input/touchscreen/Kconfig +3 -0

+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C

Since we include linux/of.h, I think we should also add:
depends on OF

Thank you, will do and resubmit.

Quoted 185 lines

There are some small nitpicks below as well.

With those addressed, please add:

Reviewed-by Mattijs Korpershoek <[email protected]>

Quoted 164 lines

drivers/input/touchscreen/Kconfig +9 -0

+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile +1 -0

index 557f84fd2075..43860ca19b98 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o

drivers/input/touchscreen/hynitron_cstxxx.c new file +134 -0

new file mode 100644
index 000000000000..11701ff39eb1
@@ -0,0 +1,508 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Driver for Hynitron cstxxx Touchscreen
+ *
+ *  Copyright (c) 2022 Chris Morgan <[email protected]>
+ *
+ *  This code is based on hynitron_core.c authored by Hynitron.
+ *  Note that no datasheet was available, so much of these registers
+ *  are undocumented. This is essentially a cleaned-up version of the
+ *  vendor driver with support removed for hardware I cannot test and
+ *  device-specific functions replated with generic functions wherever
+ *  possible.
+ */
+
+#include <asm/unaligned.h>
+#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/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Per chip data */
+struct hynitron_ts_chip_data {
+	unsigned int max_touch_num;
+	u32 ic_chkcode;
+	int (*firmware_info)(struct i2c_client *client);
+	int (*bootloader_enter)(struct i2c_client *client);
+	int (*init_input)(struct i2c_client *client);
+	void (*report_touch)(struct i2c_client *client);
+};
+
+/* Data generic to all (supported and non-supported) controllers. */
+struct hynitron_ts_data {
+	const struct hynitron_ts_chip_data *pdata;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *irq_gpio;
+};
+
+/*
+ * Since I have no datasheet, these values are guessed and/or assumed
+ * based on observation and testing.
+ */
+#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
+#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
+#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
+#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
+#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
+
+#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
+#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
+#define CST3XX_BOOTLDR_CHK_VAL			0xac
+
+#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
+#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
+#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
+#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
+#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
+#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
+
+
+/*
+ * Hard coded reset delay value of 20ms not IC dependent in
+ * vendor driver.
+ */
+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);
+}
+
+static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	ts_data->pdata->report_touch(client);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The vendor driver would retry twice before failing to read or write
+ * to the i2c device.
+ */
+
+static int cst3xx_i2c_write(struct i2c_client *client,
+			    unsigned char *buf, int len)
+{
+	int ret;
+	int retries = 0;
+
+	while (retries < 2) {
+		ret = i2c_master_send(client, buf, len);
+		if (ret == len)
+			return 0;
+		if (ret <= 0)
+			retries++;
+		else
+			break;
+	}
+
+	return ret < 0 ? ret : -EIO;
+}
+
+static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
+				    u8 *val, u16 len)
+{
+	__le16 buf = cpu_to_le16(reg);
+	struct i2c_msg msgs[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 2,
+			.buf = (u8 *)&buf,
+		},
+		{
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = len,
+			.buf = val,
+		}
+	};

drivers/input/touchscreen/hynitron_cstxxx.c line 144

Quoted 10 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +10 -0

+	int ret;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret >= 0)
+		ret = (ret == ARRAY_SIZE(msgs) ? 0 : -EIO);
+
+	if (ret)
+		dev_err(&client->dev,
+			"Error reading %d bytes from 0x%04x: %d\n",
+			len, reg, ret);

This could be a single line, since column limit is 100chars now. This applies for a lot of other wrapped lines in this file.

Quoted 1 line

Please consider joining such lines to reduce the overall line count.

I want to confirm everyone else is okay with this change. While the column limit was changed to 100, some subsystems still prefer the old 80 limit. If everyone is okay with 100 I can do that, I just want to be sure.

Quoted 29 lines

Quoted 29 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +27 -0

+
+	return ret;
+}
+
+static int cst3xx_firmware_info(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int ret;
+	u32 tmp;
+	unsigned char buf[4];
+
+	/*
+	 * Tests suggest this command needed to read firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_START_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(10);
+
+	/*
+	 * Read register for check-code to determine if device detected
+	 * correctly.
+	 */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_CHK_CODE_REG,
+				       buf, 4);

Quoted 9 lines

drivers/input/touchscreen/hynitron_cstxxx.c line 177

Quoted 6 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +6 -0

+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if ((tmp & 0xffff0000) != ts_data->pdata->ic_chkcode) {
+		dev_err(&client->dev, "%s ic mismatch\n", __func__);

Should we print the device's ic_chkcode in case we don't recognize it?

Good idea, I'll make that change.

Quoted 129 lines

Quoted 129 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +129 -0

+		return -ENODEV;
+	}
+
+	mdelay(10);
+
+	/* Read firmware version and test if firmware missing. */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_VERSION_REG,
+				       buf, 4);
+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if (tmp == CST3XX_FIRMWARE_VER_INVALID_VAL) {
+		dev_err(&client->dev, "Device firmware missing\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Tests suggest cmd required to exit reading firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_END_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(5);
+
+	return 0;
+}
+
+static int cst3xx_bootloader_enter(struct i2c_client *client)
+{
+	int ret;
+	u8 retry;
+	u32 tmp;
+	unsigned char buf[3];
+
+	for (retry = 0; retry < 5; retry++) {
+		hyn_reset_proc(client, (7 + retry));
+		/* set cmd to enter program mode */
+		put_unaligned_le24(CST3XX_BOOTLDR_PROG_CMD, buf);
+		ret = cst3xx_i2c_write(client, buf, 3);
+		if (ret < 0)
+			continue;
+		mdelay(2);
+
+		/* check whether in program mode */
+		ret = cst3xx_i2c_read_register(client,
+					       CST3XX_BOOTLDR_PROG_CHK_REG,
+					       buf, 1);
+		tmp = get_unaligned(buf);
+
+		if (ret < 0)
+			continue;
+
+		if (tmp == CST3XX_BOOTLDR_CHK_VAL)
+			break;
+	}
+
+	if (tmp != CST3XX_BOOTLDR_CHK_VAL) {
+		dev_err(&client->dev, "%s unable to enter bootloader mode\n",
+			__func__);
+		return -ENODEV;
+	}
+
+	hyn_reset_proc(client, 40);
+
+	return 0;
+}
+
+static void cst3xx_touch_update(struct hynitron_ts_data *ts_data,
+				s32 id, s32 x, s32 y, s32 w)
+{
+	input_mt_slot(ts_data->input_dev, id);
+	input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, 1);
+	touchscreen_report_pos(ts_data->input_dev, &ts_data->prop, x, y, true);
+	input_report_abs(ts_data->input_dev, ABS_MT_TOUCH_MAJOR, w);
+}
+
+static int cst3xx_finish_touch_read(struct i2c_client *client)
+{
+	unsigned char buf[3];
+	int err;
+
+	put_unaligned_le24(CST3XX_TOUCH_DATA_STOP_CMD, buf);
+	err = cst3xx_i2c_write(client, buf, 3);
+	if (err < 0) {
+		dev_err(&client->dev, "send read touch info ending failed.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+/*
+ * Handle events from IRQ. Note that for cst3xx it appears that IRQ
+ * fires continuously while touched, otherwise once every 1500ms
+ * when not touched (assume touchscreen waking up periodically).
+ * Note buffer is sized for 5 fingers, if more needed buffer must
+ * be increased. The buffer contains 5 bytes for each touch point,
+ * a touch count byte, a check byte, and then a second check byte after
+ * all other touch points.
+ *
+ * For example 1 touch would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]
+ *
+ * 3 touches would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]:touch2[5]:touch3[5]:chk_byte[1]
+ */
+static void cst3xx_touch_report(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	unsigned char buf[28];
+	unsigned char finger_id, sw;
+	unsigned int input_x = 0;
+	unsigned int input_y = 0;
+	unsigned int input_w = 0;
+	int idx = 0;
+	int i, err;
+	int touch_cnt, end_byte;
+
+	/* Read and validate the first bits of input data. */
+	err = cst3xx_i2c_read_register(client, CST3XX_TOUCH_DATA_PART_REG,
+				       buf, 28);
+	if ((err < 0) || (buf[6] != CST3XX_TOUCH_DATA_CHK_VAL) ||
+	    (buf[0] == CST3XX_TOUCH_DATA_CHK_VAL)) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");
+		return;
+	}

Quoted 8 lines

drivers/input/touchscreen/hynitron_cstxxx.c line 311

Quoted 5 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +5 -0

+
+	/* Report to the device we're done reading the touch data. */
+	err = cst3xx_finish_touch_read(client);
+	if (err < 0) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");

We are already printing in cst3xx_finish_touch_read(), no need to print here again.

Ack.

Quoted 200 lines

Quoted 200 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +197 -0

+		return;
+	}
+
+	touch_cnt = buf[5] & CST3XX_TOUCH_COUNT_MASK;
+
+	/* If no touches registered, clear the input slots. */
+	if (touch_cnt == 0) {
+		input_mt_sync_frame(ts_data->input_dev);
+		input_sync(ts_data->input_dev);
+		return;
+	}
+
+	/*
+	 * Check the check bit of the last touch slot. The check bit is
+	 * always present after touch point 1 for valid data, and then
+	 * appears as the last byte after all other touch data.
+	 */
+	if (touch_cnt > 1) {
+		end_byte = touch_cnt * 5 + 2;
+		if (buf[end_byte] != CST3XX_TOUCH_DATA_CHK_VAL) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			return;
+		}
+	}
+
+	/* Parse through the buffer to capture touch data. */
+	for (i = 0; i < touch_cnt; i++) {
+		input_x = ((buf[idx + 1] << 4) | ((buf[idx + 3] >> 4) & 0x0f));
+		input_y = ((buf[idx + 2] << 4) | (buf[idx + 3] & 0x0f));
+		input_w = (buf[idx + 4] >> 3);
+		sw = (buf[idx] & 0x0f) >> 1;
+		finger_id = (buf[idx] >> 4) & 0x0f;
+
+		/* Sanity check we don't have more fingers than we expect */
+		if (ts_data->pdata->max_touch_num < finger_id) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			break;
+		}
+
+		/* sw value of 0 means no touch, 0x03 means touch */
+		if (sw == CST3XX_TOUCH_DATA_TOUCH_VAL)
+			cst3xx_touch_update(ts_data, finger_id,
+					    input_x, input_y, input_w);
+
+		idx += 5;
+
+		/* Skip the 2 bits between point 1 and point 2 */
+		if (i == 0)
+			idx += 2;
+	}
+
+	input_mt_sync_frame(ts_data->input_dev);
+	input_sync(ts_data->input_dev);
+}
+
+static int cst3xx_input_dev_int(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int err;
+
+	ts_data->input_dev = devm_input_allocate_device(&ts_data->client->dev);
+	if (!ts_data->input_dev) {
+		dev_err(&ts_data->client->dev,
+			"Failed to allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	ts_data->input_dev->name = "Hynitron cst3xx Touchscreen";
+	ts_data->input_dev->phys = "input/ts";
+	ts_data->input_dev->id.bustype = BUS_I2C;
+
+	input_set_drvdata(ts_data->input_dev, ts_data);
+
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(ts_data->input_dev, ABS_MT_TOUCH_MAJOR,
+			     0, 255, 0, 0);
+
+	touchscreen_parse_properties(ts_data->input_dev, true, &ts_data->prop);
+
+	if (!ts_data->prop.max_x || !ts_data->prop.max_y) {
+		dev_err(&client->dev,
+			"Invalid x/y (%d, %d), using defaults\n",
+			ts_data->prop.max_x, ts_data->prop.max_y);
+		ts_data->prop.max_x = 1152;
+		ts_data->prop.max_y = 1920;
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_X, ts_data->prop.max_x);
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_Y, ts_data->prop.max_y);
+	}
+
+	err = input_mt_init_slots(ts_data->input_dev,
+				  ts_data->pdata->max_touch_num,
+				  INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	err = input_register_device(ts_data->input_dev);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int hyn_probe(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data;
+	int err;
+
+	ts_data = devm_kzalloc(&client->dev, sizeof(*ts_data), GFP_KERNEL);
+	if (!ts_data)
+		return -ENOMEM;
+
+	ts_data->client = client;
+	i2c_set_clientdata(client, ts_data);
+
+	ts_data->reset_gpio = devm_gpiod_get(&client->dev,
+					     "reset", GPIOD_OUT_LOW);
+	err = PTR_ERR_OR_ZERO(ts_data->reset_gpio);
+	if (err < 0) {
+		dev_err(&client->dev, "request reset gpio failed: %d\n", err);
+		return err;
+	}
+
+	ts_data->pdata = of_device_get_match_data(&client->dev);
+	if (!ts_data->pdata)
+		return -EINVAL;
+
+	hyn_reset_proc(client, 60);
+
+	err = ts_data->pdata->bootloader_enter(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->init_input(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->firmware_info(client);
+	if (err < 0)
+		return err;
+
+	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					hyn_interrupt_handler,
+					IRQF_ONESHOT,
+					"Hynitron Touch Int", client);
+	if (err < 0) {
+		dev_err(&client->dev, "failed to request IRQ\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct hynitron_ts_chip_data cst3xx_data = {
+	.max_touch_num		= 5,
+	.ic_chkcode		= 0xcaca0000,
+	.firmware_info		= &cst3xx_firmware_info,
+	.bootloader_enter	= &cst3xx_bootloader_enter,
+	.init_input		= &cst3xx_input_dev_int,
+	.report_touch		= &cst3xx_touch_report,
+};
+
+static const struct i2c_device_id hyn_tpd_id[] = {
+	{ .name = "hynitron_ts", 0 },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
+
+static const struct of_device_id hyn_dt_match[] = {
+	{ .compatible = "hynitron,cst340", .data = &cst3xx_data },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, hyn_dt_match);
+
+static struct i2c_driver hynitron_i2c_driver = {
+	.driver = {
+		.name = "Hynitron-TS",
+		.of_match_table = of_match_ptr(hyn_dt_match),
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table = hyn_tpd_id,
+	.probe_new = hyn_probe,
+};
+
+module_i2c_driver(hynitron_i2c_driver);
+
+MODULE_AUTHOR("Chris Morgan");
+MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
+MODULE_LICENSE("GPL");

Signature · 1 line

2.25.1

Quoted 227 lines · Chris Morgan

Quoted 32 lines · Mattijs Korpershoek

Hi Chris,

Thank you for your patch.

Quoted 26 lines · Chris Morgan

From: Chris Morgan <[email protected]>

Add support for the Hynitron cst3xx controller found on devices such as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver was built from sources provided by Hynitron to Anbernic (possibly via Rockchip as an intermediary) and marked as GPLv2 in the code. This driver was written strictly for the cst3xx series, but in most places was left somewhat generic so support could be easily added to other devices in the future.

Signed-off-by Chris Morgan <[email protected]>

---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/hynitron_cstxxx.c | 508 ++++++++++++++++++++
 3 files changed, 521 insertions(+)
 create mode 100644 drivers/input/touchscreen/hynitron_cstxxx.c

drivers/input/touchscreen/Kconfig +0 -0

index 2d70c945b20a..9a9528e59c36 100644
@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 

Quoted 6 lines

drivers/input/touchscreen/Kconfig config TOUCHSCREEN_HYCON_HY46XX · line 427

Quoted 3 lines

drivers/input/touchscreen/Kconfig +3 -0

+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C

Since we include linux/of.h, I think we should also add:
depends on OF

Thank you, will do and resubmit.

Quoted 185 lines

There are some small nitpicks below as well.

With those addressed, please add:

Reviewed-by Mattijs Korpershoek <[email protected]>

Quoted 164 lines

drivers/input/touchscreen/Kconfig +9 -0

+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile +1 -0

index 557f84fd2075..43860ca19b98 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o

drivers/input/touchscreen/hynitron_cstxxx.c new file +134 -0

new file mode 100644
index 000000000000..11701ff39eb1
@@ -0,0 +1,508 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Driver for Hynitron cstxxx Touchscreen
+ *
+ *  Copyright (c) 2022 Chris Morgan <[email protected]>
+ *
+ *  This code is based on hynitron_core.c authored by Hynitron.
+ *  Note that no datasheet was available, so much of these registers
+ *  are undocumented. This is essentially a cleaned-up version of the
+ *  vendor driver with support removed for hardware I cannot test and
+ *  device-specific functions replated with generic functions wherever
+ *  possible.
+ */
+
+#include <asm/unaligned.h>
+#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/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Per chip data */
+struct hynitron_ts_chip_data {
+	unsigned int max_touch_num;
+	u32 ic_chkcode;
+	int (*firmware_info)(struct i2c_client *client);
+	int (*bootloader_enter)(struct i2c_client *client);
+	int (*init_input)(struct i2c_client *client);
+	void (*report_touch)(struct i2c_client *client);
+};
+
+/* Data generic to all (supported and non-supported) controllers. */
+struct hynitron_ts_data {
+	const struct hynitron_ts_chip_data *pdata;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *irq_gpio;
+};
+
+/*
+ * Since I have no datasheet, these values are guessed and/or assumed
+ * based on observation and testing.
+ */
+#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
+#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
+#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
+#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
+#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
+
+#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
+#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
+#define CST3XX_BOOTLDR_CHK_VAL			0xac
+
+#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
+#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
+#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
+#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
+#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
+#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
+
+
+/*
+ * Hard coded reset delay value of 20ms not IC dependent in
+ * vendor driver.
+ */
+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);
+}
+
+static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	ts_data->pdata->report_touch(client);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The vendor driver would retry twice before failing to read or write
+ * to the i2c device.
+ */
+
+static int cst3xx_i2c_write(struct i2c_client *client,
+			    unsigned char *buf, int len)
+{
+	int ret;
+	int retries = 0;
+
+	while (retries < 2) {
+		ret = i2c_master_send(client, buf, len);
+		if (ret == len)
+			return 0;
+		if (ret <= 0)
+			retries++;
+		else
+			break;
+	}
+
+	return ret < 0 ? ret : -EIO;
+}
+
+static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
+				    u8 *val, u16 len)
+{
+	__le16 buf = cpu_to_le16(reg);
+	struct i2c_msg msgs[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 2,
+			.buf = (u8 *)&buf,
+		},
+		{
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = len,
+			.buf = val,
+		}
+	};

drivers/input/touchscreen/hynitron_cstxxx.c line 144

Quoted 10 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +10 -0

+	int ret;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret >= 0)
+		ret = (ret == ARRAY_SIZE(msgs) ? 0 : -EIO);
+
+	if (ret)
+		dev_err(&client->dev,
+			"Error reading %d bytes from 0x%04x: %d\n",
+			len, reg, ret);

This could be a single line, since column limit is 100chars now. This applies for a lot of other wrapped lines in this file.

Quoted 6 lines

Quoted 1 line

Please consider joining such lines to reduce the overall line count.

I want to confirm everyone else is okay with this change. While the column limit was changed to 100, some subsystems still prefer the old 80 limit. If everyone is okay with 100 I can do that, I just want to be sure.

I think it's fine:

$ find drivers/input -name '*.c' -exec wc -L {} + | sort -rh
 198 total
    198 drivers/input/mouse/synaptics.c
    182 drivers/input/serio/i8042.c
    167 drivers/input/keyboard/applespi.c
    152 drivers/input/mouse/alps.c
    151 drivers/input/mouse/elantech.c
    133 drivers/input/mouse/elan_i2c_core.c
    133 drivers/input/joystick/grip.c
    133 drivers/input/joystick/adi.c
    132 drivers/input/joystick/gf2k.c
    132 drivers/input/joystick/gamecon.c
    131 drivers/input/joystick/a3d.c
    130 drivers/input/joystick/cobra.c
// ... snipp ...

I've also had some review on this on a previous driver i submitted here:
https://lore.kernel.org/all/[email protected]/

But let's wait for others to chime in. Again, this is more of a nitpick so if you'd prefer to keep at 80chars that's fine to me as well.

Thanks
Mattijs

Quoted 381 lines

Quoted 29 lines

Quoted 29 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +27 -0

+
+	return ret;
+}
+
+static int cst3xx_firmware_info(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int ret;
+	u32 tmp;
+	unsigned char buf[4];
+
+	/*
+	 * Tests suggest this command needed to read firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_START_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(10);
+
+	/*
+	 * Read register for check-code to determine if device detected
+	 * correctly.
+	 */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_CHK_CODE_REG,
+				       buf, 4);

Quoted 9 lines

drivers/input/touchscreen/hynitron_cstxxx.c line 177

Quoted 6 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +6 -0

+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if ((tmp & 0xffff0000) != ts_data->pdata->ic_chkcode) {
+		dev_err(&client->dev, "%s ic mismatch\n", __func__);

Should we print the device's ic_chkcode in case we don't recognize it?

Good idea, I'll make that change.

Quoted 129 lines

Quoted 129 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +129 -0

+		return -ENODEV;
+	}
+
+	mdelay(10);
+
+	/* Read firmware version and test if firmware missing. */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_VERSION_REG,
+				       buf, 4);
+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if (tmp == CST3XX_FIRMWARE_VER_INVALID_VAL) {
+		dev_err(&client->dev, "Device firmware missing\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Tests suggest cmd required to exit reading firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_END_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(5);
+
+	return 0;
+}
+
+static int cst3xx_bootloader_enter(struct i2c_client *client)
+{
+	int ret;
+	u8 retry;
+	u32 tmp;
+	unsigned char buf[3];
+
+	for (retry = 0; retry < 5; retry++) {
+		hyn_reset_proc(client, (7 + retry));
+		/* set cmd to enter program mode */
+		put_unaligned_le24(CST3XX_BOOTLDR_PROG_CMD, buf);
+		ret = cst3xx_i2c_write(client, buf, 3);
+		if (ret < 0)
+			continue;
+		mdelay(2);
+
+		/* check whether in program mode */
+		ret = cst3xx_i2c_read_register(client,
+					       CST3XX_BOOTLDR_PROG_CHK_REG,
+					       buf, 1);
+		tmp = get_unaligned(buf);
+
+		if (ret < 0)
+			continue;
+
+		if (tmp == CST3XX_BOOTLDR_CHK_VAL)
+			break;
+	}
+
+	if (tmp != CST3XX_BOOTLDR_CHK_VAL) {
+		dev_err(&client->dev, "%s unable to enter bootloader mode\n",
+			__func__);
+		return -ENODEV;
+	}
+
+	hyn_reset_proc(client, 40);
+
+	return 0;
+}
+
+static void cst3xx_touch_update(struct hynitron_ts_data *ts_data,
+				s32 id, s32 x, s32 y, s32 w)
+{
+	input_mt_slot(ts_data->input_dev, id);
+	input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, 1);
+	touchscreen_report_pos(ts_data->input_dev, &ts_data->prop, x, y, true);
+	input_report_abs(ts_data->input_dev, ABS_MT_TOUCH_MAJOR, w);
+}
+
+static int cst3xx_finish_touch_read(struct i2c_client *client)
+{
+	unsigned char buf[3];
+	int err;
+
+	put_unaligned_le24(CST3XX_TOUCH_DATA_STOP_CMD, buf);
+	err = cst3xx_i2c_write(client, buf, 3);
+	if (err < 0) {
+		dev_err(&client->dev, "send read touch info ending failed.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+/*
+ * Handle events from IRQ. Note that for cst3xx it appears that IRQ
+ * fires continuously while touched, otherwise once every 1500ms
+ * when not touched (assume touchscreen waking up periodically).
+ * Note buffer is sized for 5 fingers, if more needed buffer must
+ * be increased. The buffer contains 5 bytes for each touch point,
+ * a touch count byte, a check byte, and then a second check byte after
+ * all other touch points.
+ *
+ * For example 1 touch would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]
+ *
+ * 3 touches would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]:touch2[5]:touch3[5]:chk_byte[1]
+ */
+static void cst3xx_touch_report(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	unsigned char buf[28];
+	unsigned char finger_id, sw;
+	unsigned int input_x = 0;
+	unsigned int input_y = 0;
+	unsigned int input_w = 0;
+	int idx = 0;
+	int i, err;
+	int touch_cnt, end_byte;
+
+	/* Read and validate the first bits of input data. */
+	err = cst3xx_i2c_read_register(client, CST3XX_TOUCH_DATA_PART_REG,
+				       buf, 28);
+	if ((err < 0) || (buf[6] != CST3XX_TOUCH_DATA_CHK_VAL) ||
+	    (buf[0] == CST3XX_TOUCH_DATA_CHK_VAL)) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");
+		return;
+	}

Quoted 8 lines

drivers/input/touchscreen/hynitron_cstxxx.c line 311

Quoted 5 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +5 -0

+
+	/* Report to the device we're done reading the touch data. */
+	err = cst3xx_finish_touch_read(client);
+	if (err < 0) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");

We are already printing in cst3xx_finish_touch_read(), no need to print here again.

Ack.

Quoted 200 lines

Quoted 200 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +197 -0

+		return;
+	}
+
+	touch_cnt = buf[5] & CST3XX_TOUCH_COUNT_MASK;
+
+	/* If no touches registered, clear the input slots. */
+	if (touch_cnt == 0) {
+		input_mt_sync_frame(ts_data->input_dev);
+		input_sync(ts_data->input_dev);
+		return;
+	}
+
+	/*
+	 * Check the check bit of the last touch slot. The check bit is
+	 * always present after touch point 1 for valid data, and then
+	 * appears as the last byte after all other touch data.
+	 */
+	if (touch_cnt > 1) {
+		end_byte = touch_cnt * 5 + 2;
+		if (buf[end_byte] != CST3XX_TOUCH_DATA_CHK_VAL) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			return;
+		}
+	}
+
+	/* Parse through the buffer to capture touch data. */
+	for (i = 0; i < touch_cnt; i++) {
+		input_x = ((buf[idx + 1] << 4) | ((buf[idx + 3] >> 4) & 0x0f));
+		input_y = ((buf[idx + 2] << 4) | (buf[idx + 3] & 0x0f));
+		input_w = (buf[idx + 4] >> 3);
+		sw = (buf[idx] & 0x0f) >> 1;
+		finger_id = (buf[idx] >> 4) & 0x0f;
+
+		/* Sanity check we don't have more fingers than we expect */
+		if (ts_data->pdata->max_touch_num < finger_id) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			break;
+		}
+
+		/* sw value of 0 means no touch, 0x03 means touch */
+		if (sw == CST3XX_TOUCH_DATA_TOUCH_VAL)
+			cst3xx_touch_update(ts_data, finger_id,
+					    input_x, input_y, input_w);
+
+		idx += 5;
+
+		/* Skip the 2 bits between point 1 and point 2 */
+		if (i == 0)
+			idx += 2;
+	}
+
+	input_mt_sync_frame(ts_data->input_dev);
+	input_sync(ts_data->input_dev);
+}
+
+static int cst3xx_input_dev_int(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int err;
+
+	ts_data->input_dev = devm_input_allocate_device(&ts_data->client->dev);
+	if (!ts_data->input_dev) {
+		dev_err(&ts_data->client->dev,
+			"Failed to allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	ts_data->input_dev->name = "Hynitron cst3xx Touchscreen";
+	ts_data->input_dev->phys = "input/ts";
+	ts_data->input_dev->id.bustype = BUS_I2C;
+
+	input_set_drvdata(ts_data->input_dev, ts_data);
+
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(ts_data->input_dev, ABS_MT_TOUCH_MAJOR,
+			     0, 255, 0, 0);
+
+	touchscreen_parse_properties(ts_data->input_dev, true, &ts_data->prop);
+
+	if (!ts_data->prop.max_x || !ts_data->prop.max_y) {
+		dev_err(&client->dev,
+			"Invalid x/y (%d, %d), using defaults\n",
+			ts_data->prop.max_x, ts_data->prop.max_y);
+		ts_data->prop.max_x = 1152;
+		ts_data->prop.max_y = 1920;
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_X, ts_data->prop.max_x);
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_Y, ts_data->prop.max_y);
+	}
+
+	err = input_mt_init_slots(ts_data->input_dev,
+				  ts_data->pdata->max_touch_num,
+				  INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	err = input_register_device(ts_data->input_dev);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int hyn_probe(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data;
+	int err;
+
+	ts_data = devm_kzalloc(&client->dev, sizeof(*ts_data), GFP_KERNEL);
+	if (!ts_data)
+		return -ENOMEM;
+
+	ts_data->client = client;
+	i2c_set_clientdata(client, ts_data);
+
+	ts_data->reset_gpio = devm_gpiod_get(&client->dev,
+					     "reset", GPIOD_OUT_LOW);
+	err = PTR_ERR_OR_ZERO(ts_data->reset_gpio);
+	if (err < 0) {
+		dev_err(&client->dev, "request reset gpio failed: %d\n", err);
+		return err;
+	}
+
+	ts_data->pdata = of_device_get_match_data(&client->dev);
+	if (!ts_data->pdata)
+		return -EINVAL;
+
+	hyn_reset_proc(client, 60);
+
+	err = ts_data->pdata->bootloader_enter(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->init_input(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->firmware_info(client);
+	if (err < 0)
+		return err;
+
+	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					hyn_interrupt_handler,
+					IRQF_ONESHOT,
+					"Hynitron Touch Int", client);
+	if (err < 0) {
+		dev_err(&client->dev, "failed to request IRQ\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct hynitron_ts_chip_data cst3xx_data = {
+	.max_touch_num		= 5,
+	.ic_chkcode		= 0xcaca0000,
+	.firmware_info		= &cst3xx_firmware_info,
+	.bootloader_enter	= &cst3xx_bootloader_enter,
+	.init_input		= &cst3xx_input_dev_int,
+	.report_touch		= &cst3xx_touch_report,
+};
+
+static const struct i2c_device_id hyn_tpd_id[] = {
+	{ .name = "hynitron_ts", 0 },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
+
+static const struct of_device_id hyn_dt_match[] = {
+	{ .compatible = "hynitron,cst340", .data = &cst3xx_data },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, hyn_dt_match);
+
+static struct i2c_driver hynitron_i2c_driver = {
+	.driver = {
+		.name = "Hynitron-TS",
+		.of_match_table = of_match_ptr(hyn_dt_match),
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table = hyn_tpd_id,
+	.probe_new = hyn_probe,
+};
+
+module_i2c_driver(hynitron_i2c_driver);
+
+MODULE_AUTHOR("Chris Morgan");
+MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
+MODULE_LICENSE("GPL");

Signature · 1 line

2.25.1

Quoted 253 lines · Mattijs Korpershoek

Quoted 227 lines · Chris Morgan

Quoted 32 lines · Mattijs Korpershoek

Hi Chris,

Thank you for your patch.

Quoted 26 lines · Chris Morgan

From: Chris Morgan <[email protected]>

Add support for the Hynitron cst3xx controller found on devices such as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver was built from sources provided by Hynitron to Anbernic (possibly via Rockchip as an intermediary) and marked as GPLv2 in the code. This driver was written strictly for the cst3xx series, but in most places was left somewhat generic so support could be easily added to other devices in the future.

Signed-off-by Chris Morgan <[email protected]>

---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/hynitron_cstxxx.c | 508 ++++++++++++++++++++
 3 files changed, 521 insertions(+)
 create mode 100644 drivers/input/touchscreen/hynitron_cstxxx.c

drivers/input/touchscreen/Kconfig +0 -0

index 2d70c945b20a..9a9528e59c36 100644
@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 

Quoted 6 lines

drivers/input/touchscreen/Kconfig config TOUCHSCREEN_HYCON_HY46XX · line 427

Quoted 3 lines

drivers/input/touchscreen/Kconfig +3 -0

+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C

Since we include linux/of.h, I think we should also add:
depends on OF

Thank you, will do and resubmit.

Quoted 185 lines

There are some small nitpicks below as well.

With those addressed, please add:

Reviewed-by Mattijs Korpershoek <[email protected]>

Quoted 164 lines

drivers/input/touchscreen/Kconfig +9 -0

+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile +1 -0

index 557f84fd2075..43860ca19b98 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o

drivers/input/touchscreen/hynitron_cstxxx.c new file +134 -0

new file mode 100644
index 000000000000..11701ff39eb1
@@ -0,0 +1,508 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Driver for Hynitron cstxxx Touchscreen
+ *
+ *  Copyright (c) 2022 Chris Morgan <[email protected]>
+ *
+ *  This code is based on hynitron_core.c authored by Hynitron.
+ *  Note that no datasheet was available, so much of these registers
+ *  are undocumented. This is essentially a cleaned-up version of the
+ *  vendor driver with support removed for hardware I cannot test and
+ *  device-specific functions replated with generic functions wherever
+ *  possible.
+ */
+
+#include <asm/unaligned.h>
+#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/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Per chip data */
+struct hynitron_ts_chip_data {
+	unsigned int max_touch_num;
+	u32 ic_chkcode;
+	int (*firmware_info)(struct i2c_client *client);
+	int (*bootloader_enter)(struct i2c_client *client);
+	int (*init_input)(struct i2c_client *client);
+	void (*report_touch)(struct i2c_client *client);
+};
+
+/* Data generic to all (supported and non-supported) controllers. */
+struct hynitron_ts_data {
+	const struct hynitron_ts_chip_data *pdata;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *irq_gpio;
+};
+
+/*
+ * Since I have no datasheet, these values are guessed and/or assumed
+ * based on observation and testing.
+ */
+#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
+#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
+#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
+#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
+#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
+
+#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
+#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
+#define CST3XX_BOOTLDR_CHK_VAL			0xac
+
+#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
+#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
+#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
+#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
+#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
+#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
+
+
+/*
+ * Hard coded reset delay value of 20ms not IC dependent in
+ * vendor driver.
+ */
+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);
+}
+
+static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	ts_data->pdata->report_touch(client);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The vendor driver would retry twice before failing to read or write
+ * to the i2c device.
+ */
+
+static int cst3xx_i2c_write(struct i2c_client *client,
+			    unsigned char *buf, int len)
+{
+	int ret;
+	int retries = 0;
+
+	while (retries < 2) {
+		ret = i2c_master_send(client, buf, len);
+		if (ret == len)
+			return 0;
+		if (ret <= 0)
+			retries++;
+		else
+			break;
+	}
+
+	return ret < 0 ? ret : -EIO;
+}
+
+static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
+				    u8 *val, u16 len)
+{
+	__le16 buf = cpu_to_le16(reg);
+	struct i2c_msg msgs[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 2,
+			.buf = (u8 *)&buf,
+		},
+		{
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = len,
+			.buf = val,
+		}
+	};

drivers/input/touchscreen/hynitron_cstxxx.c line 144

Quoted 10 lines

drivers/input/touchscreen/hynitron_cstxxx.c new file +10 -0

+	int ret;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret >= 0)
+		ret = (ret == ARRAY_SIZE(msgs) ? 0 : -EIO);
+
+	if (ret)
+		dev_err(&client->dev,
+			"Error reading %d bytes from 0x%04x: %d\n",
+			len, reg, ret);

This could be a single line, since column limit is 100chars now. This applies for a lot of other wrapped lines in this file.

Quoted 6 lines

Quoted 1 line

Please consider joining such lines to reduce the overall line count.

I want to confirm everyone else is okay with this change. While the column limit was changed to 100, some subsystems still prefer the old 80 limit. If everyone is okay with 100 I can do that, I just want to be sure.

I think it's fine:

$ find drivers/input -name '*.c' -exec wc -L {} + | sort -rh
 198 total
    198 drivers/input/mouse/synaptics.c
    182 drivers/input/serio/i8042.c
    167 drivers/input/keyboard/applespi.c
    152 drivers/input/mouse/alps.c
    151 drivers/input/mouse/elantech.c
    133 drivers/input/mouse/elan_i2c_core.c
    133 drivers/input/joystick/grip.c
    133 drivers/input/joystick/adi.c
    132 drivers/input/joystick/gf2k.c
    132 drivers/input/joystick/gamecon.c
    131 drivers/input/joystick/a3d.c
    130 drivers/input/joystick/cobra.c
// ... snipp ...

Quoted 6 lines

I've also had some review on this on a previous driver i submitted here:
https://lore.kernel.org/all/[email protected]/

But let's wait for others to chime in. Again, this is more of a nitpick so if you'd prefer to keep at 80chars that's fine to me as well.

I'll keep it at 80 for now,

Hi Chris,

Thank you for your patch.

Quoted 26 lines · Chris Morgan

From: Chris Morgan <[email protected]>

Add support for the Hynitron cst3xx controller found on devices such as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver was built from sources provided by Hynitron to Anbernic (possibly via Rockchip as an intermediary) and marked as GPLv2 in the code. This driver was written strictly for the cst3xx series, but in most places was left somewhat generic so support could be easily added to other devices in the future.

Signed-off-by Chris Morgan <[email protected]>

---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/hynitron_cstxxx.c | 508 ++++++++++++++++++++
 3 files changed, 521 insertions(+)
 create mode 100644 drivers/input/touchscreen/hynitron_cstxxx.c

drivers/input/touchscreen/Kconfig +0 -0

index 2d70c945b20a..9a9528e59c36 100644
@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 

drivers/input/touchscreen/Kconfig config TOUCHSCREEN_HYCON_HY46XX · line 427

Quoted 3 lines

drivers/input/touchscreen/Kconfig +3 -0

+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C

Since we include linux/of.h, I think we should also add:
depends on OF