Date:	Tue, 2 Aug 2016 12:52:30 +0300
From:	<mika.penttila@...tfour.com>
To:	<linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:	<tammy_tseng@....com>, <yuger_yu@....com>,
	Mika Penttilä <mika.penttila@...tfour.com>
Subject: [PATCH v6 1/2] Input: Driver for SiS-9200 family I2C touchscreen controller

From: Mika Penttilä <mika.penttila@...tfour.com>

Multitouch protocol B support.

v6:
  - rebased to 4.7
  - simplify logic : send input reports while reading
    i2c packets
  - more cleanups

v5:
  - rebased to 4.6.0-rc6

v4:
  - cleanups and fixes according to review feedback
  - irq and reset gpios are now optional,
    if not spesified it is expected the firmware / hw
    takes care of reset states and irq flow
  - irq and reset gpio polarities come from dts/firmware
  - report parsing and reporting are done at once
  - error handling improvements
  - misc cleanups
  - added comments
    
v3:
  - cleanup unused defines
  - added acked-bys from SiS

v2:
  - use gpio descriptor api
  - probe cleanups
  - error handling cleanups

Signed-off-by: Mika Penttilä <mika.penttila@...tfour.com>
Acked-by: Tammy Tseng <tammy_tseng@....com>
Acked-by: Yuger Yu <yuger_yu@....com>
---
 drivers/input/touchscreen/Kconfig   |  12 ++
 drivers/input/touchscreen/Makefile  |   2 +
 drivers/input/touchscreen/sis_i2c.c | 409 ++++++++++++++++++++++++++++++++++++
 3 files changed, 423 insertions(+)
 create mode 100644 drivers/input/touchscreen/sis_i2c.c

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index ee02dc7..0633e8c 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
+	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..cbb484f 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
@@ -97,3 +98,4 @@ obj-$(CONFIG_TOUCHSCREEN_TPS6507X)	+= tps6507x-ts.o
 obj-$(CONFIG_TOUCHSCREEN_ZFORCE)	+= zforce_ts.o
 obj-$(CONFIG_TOUCHSCREEN_COLIBRI_VF50)	+= colibri-vf50-ts.o
 obj-$(CONFIG_TOUCHSCREEN_ROHM_BU21023)	+= rohm_bu21023.o
+
diff --git a/drivers/input/touchscreen/sis_i2c.c b/drivers/input/touchscreen/sis_i2c.c
new file mode 100644
index 0000000..51caad3
--- /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) 2016 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_CONTACT_STATUS_OFFSET	0
+#define SIS_CONTACT_ID_OFFSET		1 /* Contact ID */
+#define SIS_CONTACT_X_OFFSET		2
+#define SIS_CONTACT_Y_OFFSET		4
+#define SIS_CONTACT_WIDTH_OFFSET	6
+#define SIS_CONTACT_HEIGHT_OFFSET	7
+#define SIS_CONTACT_PRESSURE_OFFSET(id)	(SIS_PKT_HAS_AREA(id) ? 8 : 6)
+
+/* Individual contact state */
+#define SIS_STATUS_UP			0x0
+#define SIS_STATUS_DOWN			0x3
+
+/* 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_REPORT_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 + 2,
+					len - 2 - 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_CONTACT_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_CONTACT_STATUS_OFFSET]);
+		return -EINVAL;
+	}
+
+	slot = input_mt_get_slot_by_key(input, data[SIS_CONTACT_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_CONTACT_WIDTH_OFFSET];
+				height = data[SIS_CONTACT_HEIGHT_OFFSET];
+			}
+
+			if (SIS_PKT_HAS_PRESSURE(id))
+				pressure = data[SIS_CONTACT_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_CONTACT_X_OFFSET]));
+		input_report_abs(input, ABS_MT_POSITION_Y,
+				 get_unaligned_le16(&data[SIS_CONTACT_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");
+MODULE_AUTHOR("Mika Penttilä <mika.penttila@...tfour.com>");
-- 
1.9.1

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