Hi Mika,

On Fri, May 06, 2016 at 08:22:16AM +0300, mika.penttila@nextfour.com wrote:

Not needed I think.

+#include <linux/platform_device.h>

Not needed.

+#include <linux/linkage.h>

Not needed.

+#include <linux/slab.h>
+#include <linux/of_gpio.h>

Not needed (but gpio/consumer.h is)

+#include <linux/uaccess.h>
+#include <linux/irq.h>

Not needed I think.

+#include <asm/unaligned.h>
+#include <linux/crc-itu-t.h>
+
+#define SIS_I2C_NAME "sis_i2c_ts"
+#define MAX_FINGERS					10
+
+#define SIS_MAX_X					4095
+#define SIS_MAX_Y					4095
+
+#define PACKET_BUFFER_SIZE				128
+
+#define SIS_CMD_NORMAL					0x0
+
+#define TOUCHDOWN                                       0x3
+#define TOUCHUP                                         0x0
+#define MAX_BYTE					 64
+#define PRESSURE_MAX                                    255
+
+/* Resolution diagonal */
+#define AREA_LENGTH_LONGER				5792
+/*((SIS_MAX_X^2) + (SIS_MAX_Y^2))^0.5*/
+#define AREA_LENGTH_SHORT				5792
+#define AREA_UNIT					(5792/32)
+
+#define P_BYTECOUNT					0
+#define ALL_IN_ONE_PACKAGE				0x10
+#define IS_TOUCH(x)					((x) & 0x1)
+#define IS_HIDI2C(x)					(((x) & 0xF) == 0x06)
+#define IS_AREA(x)					(((x) >> 4) & 0x1)
+#define IS_PRESSURE(x)				        (((x) >> 5) & 0x1)
+#define IS_SCANTIME(x)			                (((x) >> 6) & 0x1)
+
+#define NORMAL_LEN_PER_POINT			        6
+#define AREA_LEN_PER_POINT				2
+#define PRESSURE_LEN_PER_POINT			        1
+
+#define TOUCH_FORMAT					0x1
+#define HIDI2C_FORMAT					0x6
+#define P_REPORT_ID					2
+#define BYTE_BYTECOUNT					2
+#define BYTE_REPORTID					1
+#define BYTE_CRC_HIDI2C                                 0
+#define BYTE_CRC_I2C					2
+#define BYTE_SCANTIME					2
+
+struct _touchpoint {
+	u8 id;
+	u16 x, y;
+	u16 pressure;
+	u16 width;
+	u16 height;
+};
+
+struct sistp_driver_data {
+	int fingers;
+	struct _touchpoint pt[MAX_FINGERS];
+};
+
+struct sis_ts_data {
+	struct gpio_desc *irq_gpiod;
+	struct gpio_desc *reset_gpiod;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+struct sistp_driver_data tpinfo;

There is actually no need to have storage for contact info in the driver
object, you can report them as you parse them.

+};
+
+static int sis_cul_unit(u8 report_id)
+{
+	int ret = NORMAL_LEN_PER_POINT;
+
+	if (report_id != ALL_IN_ONE_PACKAGE) {
+
+		if (IS_AREA(report_id) /*&& IS_TOUCH(report_id)*/)
+			ret += AREA_LEN_PER_POINT;
+
+		if (IS_PRESSURE(report_id))
+			ret += PRESSURE_LEN_PER_POINT;
+	}
+
+	return ret;
+}
+
+static int sis_readpacket(struct i2c_client *client, u8 cmd, u8 *buf)
+{
+	u8 tmpbuf[MAX_BYTE] = {0};
+	int ret = -1;
+	int touchnum = 0;
+	int p_count = 0;
+	int touch_format_id = 0;
+	int location = 0;
+	bool read_first = true;
+
+/*
+ * I2C touch report format
+ *
+ * The controller sends one or two
+ * 64 byte reports (depending on how many
+ * contacts down etc). We read first 64 bytes
+ * and then the second chunk if needed.
+ * The packets are individually CRC
+ * checksummed.
+ *
+ * buf[0] = Low 8 bits of byte count value
+ * buf[1] = High 8 bits of byte counte value
+ * buf[2] = Report ID
+ * buf[touch num * 6 + 2 ] = Touch information
+ * 1 touch point has 6 bytes, it could be none if no touch
+ * buf[touch num * 6 + 3] = Touch numbers
+ *
+ * One touch point information include 6 bytes, the order is
+ *
+ * 1. status = touch down or touch up
+ * 2. id = finger id
+ * 3. x axis low 8 bits
+ * 4. x axis high 8 bits
+ * 5. y axis low 8 bits
+ * 6. y axis high 8 bits
+ */
+	do {
+		if (location >= PACKET_BUFFER_SIZE) {
+			dev_err(&client->dev, "sis_readpacket: buffer overflow\n");
+			return -1;
+		}
+
+		ret = i2c_master_recv(client, tmpbuf, MAX_BYTE);
+
+		if (ret <= 0) {
+			return touchnum;
+		} else if (tmpbuf[P_BYTECOUNT] > MAX_BYTE) {
+			dev_err(&client->dev, "sis_readpacket: invalid bytecout\n");
+			return -1;
+		}
+
+		if (tmpbuf[P_BYTECOUNT] < 10)
+			return touchnum;
+
+		if (read_first)
+			if (tmpbuf[P_BYTECOUNT] == 0)
+				return 0;	/* touchnum is 0 */
+
+		touch_format_id = tmpbuf[P_REPORT_ID] & 0xf;
+
+		if ((touch_format_id != TOUCH_FORMAT)
+			&& (touch_format_id != HIDI2C_FORMAT)
+			&& (tmpbuf[P_REPORT_ID] != ALL_IN_ONE_PACKAGE)) {
+			dev_err(&client->dev, "sis_readpacket: invalid reportid\n");
+			return -1;
+		}
+
+		p_count = (int) tmpbuf[P_BYTECOUNT] - 1; /* start from 0 */
+		if (tmpbuf[P_REPORT_ID] != ALL_IN_ONE_PACKAGE) {
+			if (IS_TOUCH(tmpbuf[P_REPORT_ID])) {
+				p_count -= BYTE_CRC_I2C; /* delete 2 byte crc */
+			} else if (IS_HIDI2C(tmpbuf[P_REPORT_ID])) {
+				p_count -= BYTE_CRC_HIDI2C;
+			} else {
+				dev_err(&client->dev, "sis_readpacket: delete crc error\n");
+				return -1;
+			}
+			if (IS_SCANTIME(tmpbuf[P_REPORT_ID]))
+				p_count -= BYTE_SCANTIME;
+		}
+
+		if (read_first)
+			touchnum = tmpbuf[p_count];
+		else {
+			if (tmpbuf[p_count] != 0) {
+				dev_err(&client->dev, "sis_readpacket: nonzero point count in tail packet\n");
+				return -1;
+			}
+		}
+
+		if ((touch_format_id != HIDI2C_FORMAT) &&
+			(tmpbuf[P_BYTECOUNT] > 3)) {
+			int crc_end = p_count +
+				(IS_SCANTIME(tmpbuf[P_REPORT_ID]) * 2);
+			u16 buf_crc =
+				crc_itu_t(0, tmpbuf + 2, crc_end - 1);
+			int l_package_crc =
+				(IS_SCANTIME(tmpbuf[P_REPORT_ID]) * 2) +
+				p_count + 1;
+			u16 package_crc =
+				get_unaligned_le16(&tmpbuf[l_package_crc]);
+			if (buf_crc != package_crc) {
+				dev_err(&client->dev, "sis_readpacket: CRC Error\n");
+				return -1;
+			}
+		}
+
+		memcpy(&buf[location], &tmpbuf[0], 64);
+		/* Buf_Data [0~63] [64~128] */
+		location += MAX_BYTE;
+		read_first = false;
+	} while (tmpbuf[P_REPORT_ID] != ALL_IN_ONE_PACKAGE &&
+		tmpbuf[p_count] > 5);
+
+	return touchnum;

I must say that I find this logic of combining 2 packets into one larger
confusing. I tried to rework it so that we fetch, parse and report
contacts as we go. Please see below.

+}
+
+static irqreturn_t sis_ts_irq_handler(int irq, void *dev_id)
+{
+	struct sis_ts_data *ts = dev_id;
+	struct sistp_driver_data *tpinfo = &ts->tpinfo;
+
+	int ret = -1;
+	int point_unit;
+	u8 buf[PACKET_BUFFER_SIZE] = {0};
+	u8 i = 0, fingers = 0;
+	u8 px = 0, py = 0, pstatus = 0;
+	u8 p_area = 0;
+	u8 p_preasure = 0;
+	int slot;
+
+redo:
+	/* I2C or SMBUS block data read */
+	ret = sis_readpacket(ts->client, SIS_CMD_NORMAL, buf);
+
+	if (ret < 0)
+		goto recheck_irq;
+
+	else if (ret == 0) {
+		fingers = 0;
+		goto label_sync_input;
+	}
+
+	point_unit = sis_cul_unit(buf[P_REPORT_ID]);
+	fingers = ret;
+
+	tpinfo->fingers = fingers = (fingers > MAX_FINGERS ? 0 : fingers);
+
+	for (i = 0; i < fingers; i++) {
+		if ((buf[P_REPORT_ID] != ALL_IN_ONE_PACKAGE) && (i >= 5)) {
+			pstatus = BYTE_BYTECOUNT + BYTE_REPORTID
+				+ ((i - 5) * point_unit);
+			pstatus += 64;
+		} else {
+			pstatus = BYTE_BYTECOUNT + BYTE_REPORTID
+				+ (i * point_unit);
+		}
+		/* X and Y coordinate locations */
+		px = pstatus + 2;
+		py = px + 2;
+
+		if ((buf[pstatus]) == TOUCHUP) {
+			tpinfo->pt[i].width    = 0;
+			tpinfo->pt[i].height   = 0;
+			tpinfo->pt[i].pressure = 0;
+		} else if (buf[P_REPORT_ID] == ALL_IN_ONE_PACKAGE
+			&& (buf[pstatus]) == TOUCHDOWN) {
+			tpinfo->pt[i].width    = 1;
+			tpinfo->pt[i].height   = 1;
+			tpinfo->pt[i].pressure = 1;
+		} else if ((buf[pstatus]) == TOUCHDOWN) {
+			p_area = py + 2;
+			p_preasure = py + 2 + (IS_AREA(buf[P_REPORT_ID]) * 2);
+
+			if (IS_AREA(buf[P_REPORT_ID])) {
+				tpinfo->pt[i].width = buf[p_area];
+				tpinfo->pt[i].height = buf[p_area + 1];
+			} else {
+				tpinfo->pt[i].width = 1;
+				tpinfo->pt[i].height = 1;
+			}
+
+			if (IS_PRESSURE(buf[P_REPORT_ID]))
+				tpinfo->pt[i].pressure = (buf[p_preasure]);
+			else
+				tpinfo->pt[i].pressure = 1;
+		} else {
+			dev_err(&ts->client->dev, "Touch status error\n");
+			goto recheck_irq;
+		}
+		tpinfo->pt[i].id = (buf[pstatus + 1]);
+		tpinfo->pt[i].x = le16_to_cpu(get_unaligned_le16(&buf[px]));
+		tpinfo->pt[i].y = le16_to_cpu(get_unaligned_le16(&buf[py]));

get_unaligned_le16() already converts to native CPU endianness, calling
le16_to_cpu on it is a mistake.

+
+		slot = input_mt_get_slot_by_key(
+			ts->input_dev, tpinfo->pt[i].id);
+
+		if (slot < 0)
+			continue;
+
+		input_mt_slot(ts->input_dev, slot);
+		input_mt_report_slot_state(ts->input_dev,
+					MT_TOOL_FINGER, tpinfo->pt[i].pressure);
+
+		if (tpinfo->pt[i].pressure) {
+
+			tpinfo->pt[i].width *= AREA_UNIT;
+			input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR,
+					tpinfo->pt[i].width);
+			tpinfo->pt[i].height *= AREA_UNIT;
+			input_report_abs(ts->input_dev, ABS_MT_TOUCH_MINOR,
+					tpinfo->pt[i].height);
+			input_report_abs(ts->input_dev, ABS_MT_PRESSURE,
+					tpinfo->pt[i].pressure);
+			input_report_abs(ts->input_dev, ABS_MT_POSITION_X,
+					tpinfo->pt[i].x);
+			input_report_abs(ts->input_dev, ABS_MT_POSITION_Y,
+					tpinfo->pt[i].y);
+		}
+	}
+
+label_sync_input:
+	input_mt_sync_frame(ts->input_dev);
+	input_sync(ts->input_dev);
+
+recheck_irq:
+	if (ts->irq_gpiod) {
+		/*
+		 * If provided and interrupt gpio and
+		 * irq is still asserted,
+		 * read data until interrupt is deasserted.
+		 */
+		ret = gpiod_get_value_cansleep(ts->irq_gpiod);
+		if (ret == 1)
+			goto redo;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void sis_ts_reset(struct i2c_client *client, struct sis_ts_data *ts)
+{
+
+	ts->irq_gpiod   = devm_gpiod_get_optional(&client->dev,
+						"irq", GPIOD_IN);
+	ts->reset_gpiod = devm_gpiod_get_optional(&client->dev,
+						"reset", GPIOD_OUT_LOW);
+
+	if (ts->reset_gpiod) {
+		/* Get out of reset */
+		msleep(1);

msleep(1) will not work well with low HZ values, you want to use
usleep_range().

+		gpiod_set_value(ts->reset_gpiod, 1);
+		msleep(1);
+		gpiod_set_value(ts->reset_gpiod, 0);
+		msleep(100);
+	}
+}
+
+static int sis_ts_probe(
+	struct i2c_client *client, const struct i2c_device_id *id)
+{
+	int error = 0;
+	struct sis_ts_data *ts = NULL;

No need to initialize to NULL.

+
+	ts = devm_kzalloc(&client->dev, sizeof(struct sis_ts_data), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	sis_ts_reset(client, ts);
+
+	ts->client = client;
+	i2c_set_clientdata(client, ts);
+
+	ts->input_dev = devm_input_allocate_device(&client->dev);
+	if (!ts->input_dev) {
+		dev_err(&client->dev, "sis_ts_probe: Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	ts->input_dev->name = "sis_touch";
+	ts->input_dev->id.bustype = BUS_I2C;
+
+	input_set_abs_params(ts->input_dev, ABS_MT_PRESSURE,
+			0, PRESSURE_MAX, 0, 0);
+	input_set_abs_params(ts->input_dev, ABS_MT_TOUCH_MAJOR,
+			0, AREA_LENGTH_LONGER, 0, 0);
+	input_set_abs_params(ts->input_dev, ABS_MT_TOUCH_MINOR,
+			0, AREA_LENGTH_SHORT, 0, 0);
+	input_set_abs_params(ts->input_dev, ABS_MT_POSITION_X,
+			0, SIS_MAX_X, 0, 0);
+	input_set_abs_params(ts->input_dev, ABS_MT_POSITION_Y,
+			0, SIS_MAX_Y, 0, 0);
+
+	error = input_mt_init_slots(ts->input_dev, MAX_FINGERS,
+			INPUT_MT_DROP_UNUSED | INPUT_MT_DIRECT);

It seems that the hardware keeps track of the contact identity and
reports the release events, so I do not think we need
INPUT_MT_DROP_UNUSED.

+
+	if (error) {
+		dev_err(&client->dev,
+			"failed to initialize MT slots: %d\n", error);
+		return error;
+	}
+
+	error = input_register_device(ts->input_dev);
+	if (error) {
+		dev_err(&client->dev,
+			"unable to register input device: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					sis_ts_irq_handler,
+					IRQF_ONESHOT,
+					client->name, ts);
+
+	if (error) {
+		dev_err(&client->dev, "request irq failed\n");
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id sis_ts_id[] = {
+	{ SIS_I2C_NAME, 0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, sis_ts_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id sis_ts_dt_ids[] = {
+	{ .compatible = "sis,9200_ts" },

DT folks object to using underscores in properties, this should be
"sis,9200-ts".

+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sis_ts_dt_ids);
+#endif
+
+static struct i2c_driver sis_ts_driver = {
+	.probe		= sis_ts_probe,
+	.id_table	= sis_ts_id,
+	.driver = {
+		.name	= SIS_I2C_NAME,
+		.of_match_table = of_match_ptr(sis_ts_dt_ids),
+	},
+};
+
+module_i2c_driver(sis_ts_driver);
+MODULE_DESCRIPTION("SiS 9200 Family Touchscreen Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

Below is the version of the patch with reworked parsing and reporting
code. Please let me know if it is messed up or if it works for you.

Thanks.

-- 
Dmitry


Input: add driver for SiS 9200 family I2C touchscreen controllers

From: Mika Penttilä <redacted>

This is a driver for SiS 9200 family touchscreen controllers using I2C bus.

Signed-off-by: Mika Penttilä <redacted>
Acked-by: Tammy Tseng <redacted>
Acked-by: Yuger Yu <redacted>
Patchwork-Id: 9029121
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 .../bindings/input/touchscreen/sis_i2c.txt         |   33 ++
 .../devicetree/bindings/vendor-prefixes.txt        |    1 
 drivers/input/touchscreen/Kconfig                  |   12 +
 drivers/input/touchscreen/Makefile                 |    1 
 drivers/input/touchscreen/sis_i2c.c                |  409 ++++++++++++++++++++
 5 files changed, 456 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/sis_i2c.txt
 create mode 100644 drivers/input/touchscreen/sis_i2c.c

diff --git a/Documentation/devicetree/bindings/input/touchscreen/sis_i2c.txt b/Documentation/devicetree/bindings/input/touchscreen/sis_i2c.txt
new file mode 100644
index 0000000..6b06b20
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/sis_i2c.txt

@@ -0,0 +1,33 @@
+* SiS I2C Multiple Touch Controller
+
+Required properties:
+- compatible: must be "sis,9200-ts"
+- reg: i2c slave address
+- interrupt-parent: the phandle for the interrupt controller
+  (see interrupt binding [0])
+- interrupts: touch controller interrupt (see interrupt
+  binding [0])
+
+Optional properties:
+- pinctrl-names: should be "default" (see pinctrl binding [1]).
+- pinctrl-0: a phandle pointing to the pin settings for the
+  device (see pinctrl binding [1]).
+- attn-gpio: the gpio pin used as attention line
+- reset-gpio: the gpio pin used to reset the controller
+- wakeup-source: touchscreen can be used as a wakeup source
+
+[0]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+[1]: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
+
+Example:
+
+	sis9255@5c  {
+		compatible = "sis,9200-ts";
+		reg = <0x5c>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_sis>;
+		interrupt-parent = <&gpio3>;
+		interrupts = <19 IRQ_TYPE_EDGE_FALLING>;
+		attn-gpio = <&gpio3 19 GPIO_ACTIVE_LOW>;
+		reset-gpio = <&gpio2 30 GPIO_ACTIVE_LOW>;
+	};

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index 80fdbe2..99029cf 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -221,6 +221,7 @@ simtek
 sii	Seiko Instruments, Inc.
 silergy	Silergy Corp.
 sirf	SiRF Technology, Inc.
+sis	Silicon Integrated Systems Corp.
 sitronix	Sitronix Technology Corporation
 skyworks	Skyworks Solutions, Inc.
 smsc	Standard Microsystems Corporation

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index ee02dc7..9a29ad1 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig

@@ -1181,4 +1181,16 @@ config TOUCHSCREEN_ROHM_BU21023
 	  To compile this driver as a module, choose M here: the
 	  module will be called bu21023_ts.
 
+config TOUCHSCREEN_SIS_I2C
+	tristate "SiS 9200 family I2C touchscreen driver"
+	depends on I2C
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  This enables support for SiS 9200 family over I2C based touchscreens.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called sis_i2c.
+
 endif

diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 3315882..e547399 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile

@@ -64,6 +64,7 @@ obj-$(CONFIG_TOUCHSCREEN_PENMOUNT)	+= penmount.o
 obj-$(CONFIG_TOUCHSCREEN_PIXCIR)	+= pixcir_i2c_ts.o
 obj-$(CONFIG_TOUCHSCREEN_RM_TS)		+= raydium_i2c_ts.o
 obj-$(CONFIG_TOUCHSCREEN_S3C2410)	+= s3c2410_ts.o
+obj-$(CONFIG_TOUCHSCREEN_SIS_I2C)       += sis_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_ST1232)	+= st1232.o
 obj-$(CONFIG_TOUCHSCREEN_STMPE)		+= stmpe-ts.o
 obj-$(CONFIG_TOUCHSCREEN_SUN4I)		+= sun4i-ts.o

diff --git a/drivers/input/touchscreen/sis_i2c.c b/drivers/input/touchscreen/sis_i2c.c
new file mode 100644
index 0000000..bc96c9d
--- /dev/null
+++ b/drivers/input/touchscreen/sis_i2c.c

@@ -0,0 +1,409 @@
+/*
+ * Touch Screen driver for SiS 9200 family I2C Touch panels
+ *
+ * Copyright (C) 2015 SiS, Inc.
+ * Copyright (C) 2015 Nextfour Group
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/crc-itu-t.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/interrupt.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <asm/unaligned.h>
+
+#define SIS_I2C_NAME		"sis_i2c_ts"
+
+/*
+ * The I2C packet format:
+ * le16		byte count
+ * u8		Report ID
+ * <contact data - variable length>
+ * u8		Number of contacts
+ * le16		Scan Time (optional?)
+ * le16		CRC
+ *
+ * One touch point information consists of 6+ bytes, the order is:
+ * u8		contact state
+ * u8		finger id
+ * le16		x axis
+ * le16		y axis
+ * u8		contact width (optional)
+ * u8		contact height (optional)
+ * u8		pressure (optional)
+ *
+ * Maximum amount of data transmitted in one shot is 64 bytes, if controller
+ * needs to report more contacts than fit in one packet it will send true number
+ * of contacts in first packet and 0 as number of contacts in second packet.
+ */
+
+#define SIS_MAX_PACKET_SIZE		64
+
+#define SIS_PKT_LEN_OFFSET		0
+#define SIS_PKT_REPORT_OFFSET		2 /* Report ID/type */
+#define SIS_PKT_CONTACT_OFFSET		3 /* First contact */
+
+#define SIS_SCAN_TIME_LEN		2
+
+/* Supported report types */
+#define SIS_ALL_IN_ONE_PACKAGE		0x10
+#define SIS_PKT_IS_TOUCH(x)		(((x) & 0x0f) == 0x01)
+#define SIS_PKT_IS_HIDI2C(x)		(((x) & 0x0f) == 0x06)
+
+/* Contact properties within report */
+#define SIS_PKT_HAS_AREA(x)		((x) & BIT(4))
+#define SIS_PKT_HAS_PRESSURE(x)		((x) & BIT(5))
+#define SIS_PKT_HAS_SCANTIME(x)		((x) & BIT(6))
+
+/* Contact size */
+#define SIS_BASE_LEN_PER_CONTACT	6
+#define SIS_AREA_LEN_PER_CONTACT	2
+#define SIS_PRESSURE_LEN_PER_CONTACT	1
+
+/* Offsets within contact data */
+#define SIS_PKT_STATUS_OFFSET		0
+#define SIS_PKT_ID_OFFSET		1 /* Contact ID */
+#define SIS_PKT_X_OFFSET		2
+#define SIS_PKT_Y_OFFSET		4
+#define SIS_PKT_WIDTH_OFFSET		6
+#define SIS_PKT_HEIGHT_OFFSET		7
+#define SIS_PKT_PRESSURE_OFFSET(id)	(SIS_PKT_HAS_AREA(id) ? 8 : 6)
+
+/* Individual contact state */
+#define SIS_STATUS_UP			0x3
+#define SIS_STATUS_DOWN			0x0
+
+/* Touchscreen parameters */
+#define SIS_MAX_FINGERS			10
+#define SIS_MAX_X			4095
+#define SIS_MAX_Y			4095
+#define SIS_MAX_PRESSURE		255
+
+/* Resolution diagonal */
+#define SIS_AREA_LENGTH_LONGER		5792
+/*((SIS_MAX_X^2) + (SIS_MAX_Y^2))^0.5*/
+#define SIS_AREA_LENGTH_SHORT		5792
+#define SIS_AREA_UNIT			(5792/32)
+
+struct sis_ts_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+
+	struct gpio_desc *attn_gpio;
+	struct gpio_desc *reset_gpio;
+
+	u8 packet[SIS_MAX_PACKET_SIZE];
+};
+
+static int sis_read_packet(struct i2c_client *client, u8 *buf,
+			   unsigned int *num_contacts,
+			   unsigned int *contact_size)
+{
+	int count_idx;
+	int ret;
+	u16 len;
+	u16 crc, pkg_crc;
+	u8 report_id;
+
+	ret = i2c_master_recv(client, buf, SIS_MAX_PACKET_SIZE);
+	if (ret <= 0)
+		return -EIO;
+
+	len = get_unaligned_le16(&buf[SIS_PKT_LEN_OFFSET]);
+	if (len > SIS_MAX_PACKET_SIZE) {
+		dev_err(&client->dev,
+			"%s: invalid packet length (%d vs %d)\n",
+			__func__, len, SIS_MAX_PACKET_SIZE);
+		return -E2BIG;
+	}
+
+	if (len < 10)
+		return -EINVAL;
+
+	report_id = buf[SIS_PKT_ID_OFFSET];
+	count_idx  = len - 1;
+	*contact_size = SIS_BASE_LEN_PER_CONTACT;
+
+	if (report_id != SIS_ALL_IN_ONE_PACKAGE) {
+		if (SIS_PKT_IS_TOUCH(report_id)) {
+			/*
+			 * Calculate CRC ignoring packet length
+			 * in the beginning and CRC transmitted
+			 * at the end of the packet.
+			 */
+			crc = crc_itu_t(0, buf + SIS_PKT_LEN_OFFSET,
+					len - SIS_PKT_LEN_OFFSET - 2);
+			pkg_crc = get_unaligned_le16(&buf[len - 2]);
+
+			if (crc != pkg_crc) {
+				dev_err(&client->dev,
+					"%s: CRC Error (%d vs %d)\n",
+					__func__, crc, pkg_crc);
+				return -EINVAL;
+			}
+
+			count_idx -= 2;
+
+		} else if (!SIS_PKT_IS_HIDI2C(report_id)) {
+			dev_err(&client->dev,
+				"%s: invalid packet ID %#02x\n",
+				__func__, report_id);
+			return -EINVAL;
+		}
+
+		if (SIS_PKT_HAS_SCANTIME(report_id))
+			count_idx -= SIS_SCAN_TIME_LEN;
+
+		if (SIS_PKT_HAS_AREA(report_id))
+			*contact_size += SIS_AREA_LEN_PER_CONTACT;
+		if (SIS_PKT_HAS_PRESSURE(report_id))
+			*contact_size += SIS_PRESSURE_LEN_PER_CONTACT;
+	}
+
+	*num_contacts = buf[count_idx];
+	return 0;
+}
+
+static int sis_ts_report_contact(struct sis_ts_data *ts, const u8 *data, u8 id)
+{
+	struct input_dev *input = ts->input;
+	int slot;
+	u8 status = data[SIS_PKT_STATUS_OFFSET];
+	u8 pressure;
+	u8 height, width;
+
+	if (status != SIS_STATUS_DOWN && status != SIS_STATUS_UP) {
+		dev_err(&ts->client->dev, "Unexpected touch status: %#02x\n",
+			data[SIS_PKT_STATUS_OFFSET]);
+		return -EINVAL;
+	}
+
+	slot = input_mt_get_slot_by_key(input, data[SIS_PKT_ID_OFFSET]);
+	if (slot < 0)
+		return -ENOENT;
+
+	input_mt_slot(input, slot);
+	input_mt_report_slot_state(input, MT_TOOL_FINGER,
+				   status == SIS_STATUS_DOWN);
+
+	if (status == SIS_STATUS_DOWN) {
+		pressure = height = width = 1;
+		if (id != SIS_ALL_IN_ONE_PACKAGE) {
+			if (SIS_PKT_HAS_AREA(id)) {
+				width = data[SIS_PKT_WIDTH_OFFSET];
+				height = data[SIS_PKT_HEIGHT_OFFSET];
+			}
+
+			if (SIS_PKT_HAS_PRESSURE(id))
+				pressure = data[SIS_PKT_PRESSURE_OFFSET(id)];
+		}
+
+		input_report_abs(input, ABS_MT_TOUCH_MAJOR,
+				 width * SIS_AREA_UNIT);
+		input_report_abs(input, ABS_MT_TOUCH_MINOR,
+				 height * SIS_AREA_UNIT);
+		input_report_abs(input, ABS_MT_PRESSURE, pressure);
+		input_report_abs(input, ABS_MT_POSITION_X,
+				 get_unaligned_le16(&data[SIS_PKT_X_OFFSET]));
+		input_report_abs(input, ABS_MT_POSITION_Y,
+				 get_unaligned_le16(&data[SIS_PKT_Y_OFFSET]));
+	}
+
+	return 0;
+}
+
+static void sis_ts_handle_packet(struct sis_ts_data *ts)
+{
+	const u8 *contact;
+	unsigned int num_to_report = 0;
+	unsigned int num_contacts;
+	unsigned int num_reported;
+	unsigned int contact_size;
+	int error;
+	u8 report_id;
+
+	do {
+		error = sis_read_packet(ts->client, ts->packet,
+					&num_contacts, &contact_size);
+		if (error)
+			break;
+
+		if (num_to_report == 0) {
+			num_to_report = num_contacts;
+		} else if (num_contacts != 0) {
+			dev_err(&ts->client->dev,
+				"%s: nonzero (%d) point count in tail packet\n",
+				__func__, num_contacts);
+			break;
+		}
+
+		report_id = ts->packet[SIS_PKT_REPORT_OFFSET];
+		contact = &ts->packet[SIS_PKT_CONTACT_OFFSET];
+		num_reported = 0;
+
+		while (num_to_report > 0) {
+			error = sis_ts_report_contact(ts, contact, report_id);
+			if (error)
+				break;
+
+			contact += contact_size;
+			num_to_report--;
+			num_reported++;
+
+			if (report_id != SIS_ALL_IN_ONE_PACKAGE &&
+			    num_reported >= 5) {
+				/*
+				 * The remainder of contacts is sent
+				 * in the 2nd packet.
+				 */
+				break;
+			}
+		}
+	} while (num_to_report > 0);
+
+	input_mt_sync_frame(ts->input);
+	input_sync(ts->input);
+}
+
+static irqreturn_t sis_ts_irq_handler(int irq, void *dev_id)
+{
+	struct sis_ts_data *ts = dev_id;
+
+	do {
+		sis_ts_handle_packet(ts);
+	} while (ts->attn_gpio && gpiod_get_value_cansleep(ts->attn_gpio));
+
+	return IRQ_HANDLED;
+}
+
+static void sis_ts_reset(struct sis_ts_data *ts)
+{
+	if (ts->reset_gpio) {
+		/* Get out of reset */
+		usleep_range(1000, 2000);
+		gpiod_set_value(ts->reset_gpio, 1);
+		usleep_range(1000, 2000);
+		gpiod_set_value(ts->reset_gpio, 0);
+		msleep(100);
+	}
+}
+
+static int sis_ts_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct sis_ts_data *ts;
+	struct input_dev *input;
+	int error;
+
+	ts = devm_kzalloc(&client->dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = client;
+	i2c_set_clientdata(client, ts);
+
+	ts->attn_gpio = devm_gpiod_get_optional(&client->dev,
+						"attn", GPIOD_IN);
+	if (IS_ERR(ts->attn_gpio)) {
+		error = PTR_ERR(ts->attn_gpio);
+		if (error != -EPROBE_DEFER)
+			dev_err(&client->dev,
+				"Failed to get attention GPIO: %d\n", error);
+		return error;
+	}
+
+	ts->reset_gpio = devm_gpiod_get_optional(&client->dev,
+						 "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(ts->reset_gpio)) {
+		error = PTR_ERR(ts->reset_gpio);
+		if (error != -EPROBE_DEFER)
+			dev_err(&client->dev,
+				"Failed to get reset GPIO: %d\n", error);
+		return error;
+	}
+
+	sis_ts_reset(ts);
+
+	ts->input = input = devm_input_allocate_device(&client->dev);
+	if (!input) {
+		dev_err(&client->dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	input->name = "SiS Touchscreen";
+	input->id.bustype = BUS_I2C;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0, SIS_MAX_X, 0, 0);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, SIS_MAX_Y, 0, 0);
+	input_set_abs_params(input, ABS_MT_PRESSURE, 0, SIS_MAX_PRESSURE, 0, 0);
+	input_set_abs_params(input, ABS_MT_TOUCH_MAJOR,
+			     0, SIS_AREA_LENGTH_LONGER, 0, 0);
+	input_set_abs_params(input, ABS_MT_TOUCH_MINOR,
+			     0, SIS_AREA_LENGTH_SHORT, 0, 0);
+
+	error = input_mt_init_slots(input, SIS_MAX_FINGERS, INPUT_MT_DIRECT);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to initialize MT slots: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(&client->dev, client->irq,
+					  NULL, sis_ts_irq_handler,
+					  IRQF_ONESHOT,
+					  client->name, ts);
+	if (error) {
+		dev_err(&client->dev, "Failed to request IRQ: %d\n", error);
+		return error;
+	}
+
+	error = input_register_device(ts->input);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id sis_ts_dt_ids[] = {
+	{ .compatible = "sis,9200-ts" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sis_ts_dt_ids);
+#endif
+
+static const struct i2c_device_id sis_ts_id[] = {
+	{ SIS_I2C_NAME,	0 },
+	{ "9200-ts",	0 },
+	{ /* sentinel */  }
+};
+MODULE_DEVICE_TABLE(i2c, sis_ts_id);
+
+static struct i2c_driver sis_ts_driver = {
+	.driver = {
+		.name	= SIS_I2C_NAME,
+		.of_match_table = of_match_ptr(sis_ts_dt_ids),
+	},
+	.probe		= sis_ts_probe,
+	.id_table	= sis_ts_id,
+};
+module_i2c_driver(sis_ts_driver);
+
+MODULE_DESCRIPTION("SiS 9200 Family Touchscreen Driver");
+MODULE_LICENSE("GPL v2");

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