This patch adds Goodix GT801 2+1 touchscreen controller support.

GT801 2+1 is a 10-finger touch controller consisting of
ARM controller interfacing two GT801 5-finger controllers.

Signed-off-by: Priit Laes <pl...@plaes.org>
---
 .../bindings/input/touchscreen/gt801_2plus1.txt    |  23 ++
 MAINTAINERS                                        |   6 +
 drivers/input/touchscreen/Kconfig                  |  19 +-
 drivers/input/touchscreen/Makefile                 |   1 +
 drivers/input/touchscreen/gt801_2plus1.c           | 375 +++++++++++++++++++++
 5 files changed, 421 insertions(+), 3 deletions(-)
 create mode 100644 
Documentation/devicetree/bindings/input/touchscreen/gt801_2plus1.txt
 create mode 100644 drivers/input/touchscreen/gt801_2plus1.c

diff --git 
a/Documentation/devicetree/bindings/input/touchscreen/gt801_2plus1.txt 
b/Documentation/devicetree/bindings/input/touchscreen/gt801_2plus1.txt
new file mode 100644
index 0000000..070ff5b
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/gt801_2plus1.txt
@@ -0,0 +1,23 @@
+Device tree bindings for Goodix GT801 2+1 series touchscreen controller
+
+Required properties:
+
+ - compatible          : Should be "goodix,gt801_2plus1"
+ - reg                 : I2C address of the chip. Should be 0x55
+ - interrupt-parent    : Interrupt controller to which the chip is connected
+ - interrupts          : Interrupt to which the chip is connected
+
+Example:
+
+       i2c@00000000 {
+               /* ... */
+
+               touchscreen@55 {
+                       compatible = "goodix,gt801_2plus1";
+                       reg = <0x55>;
+                       interrupt-parent = <&gpio>;
+                       interrupts = <0 0>;
+               };
+
+               /* ... */
+       };
diff --git a/MAINTAINERS b/MAINTAINERS
index cba790b..e292126 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4743,6 +4743,12 @@ L:       linux-in...@vger.kernel.org
 S:     Maintained
 F:     drivers/input/touchscreen/goodix.c
 
+GOODIX GT801 2PLUS1 TOUCHSCREEN
+M:     Priit Laes <pl...@plaes.org>
+L:     linux-in...@vger.kernel.org
+S:     Maintained
+F:     drivers/input/touchscreen/gt801_2plus1.c
+
 GPIO SUBSYSTEM
 M:     Linus Walleij <linus.wall...@linaro.org>
 M:     Alexandre Courbot <gnu...@gmail.com>
diff --git a/drivers/input/touchscreen/Kconfig 
b/drivers/input/touchscreen/Kconfig
index ae33da7..c7c3324 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -322,11 +322,11 @@ config TOUCHSCREEN_FUJITSU
          module will be called fujitsu-ts.
 
 config TOUCHSCREEN_GOODIX
-       tristate "Goodix I2C touchscreen"
+       tristate "Goodix GT9xx I2C touchscreen"
        depends on I2C
        help
-         Say Y here if you have the Goodix touchscreen (such as one
-         installed in Onda v975w tablets) connected to your
+         Say Y here if you have one of the Goodix GT9xx touchscreens
+         (such as one installed in Onda v975w tablet) connected to your
          system. It also supports 5-finger chip models, which can be
          found on ARM tablets, like Wexler TAB7200 and MSI Primo73.
 
@@ -335,6 +335,19 @@ config TOUCHSCREEN_GOODIX
          To compile this driver as a module, choose M here: the
          module will be called goodix.
 
+config TOUCHSCREEN_GT801_2PLUS1
+       tristate "Goodix GT801 2+1 I2C touchscreen"
+       depends on I2C
+       help
+         Say Y here if you have the Goodix GT801 2+1 touchscreen.
+         This controller is found on some older ARM tablets like
+         (Gemei G9 and Zareason Zatab).
+
+         If unsure, say N.
+
+         To compile this driver as a module, choose M here: the
+         module will be called gt801_2plus1.
+
 config TOUCHSCREEN_ILI210X
        tristate "Ilitek ILI210X based touchscreen"
        depends on I2C
diff --git a/drivers/input/touchscreen/Makefile 
b/drivers/input/touchscreen/Makefile
index cbaa6ab..ff25d1b4 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_TOUCHSCREEN_EGALAX)      += egalax_ts.o
 obj-$(CONFIG_TOUCHSCREEN_FT6236)       += ft6236.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)      += fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)       += goodix.o
+obj-$(CONFIG_TOUCHSCREEN_GT801_2PLUS1) += gt801_2plus1.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)      += ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_IMX6UL_TSC)   += imx6ul_tsc.o
 obj-$(CONFIG_TOUCHSCREEN_INEXIO)       += inexio.o
diff --git a/drivers/input/touchscreen/gt801_2plus1.c 
b/drivers/input/touchscreen/gt801_2plus1.c
new file mode 100644
index 0000000..e2be479
--- /dev/null
+++ b/drivers/input/touchscreen/gt801_2plus1.c
@@ -0,0 +1,375 @@
+/*
+ *  Driver for Goodix GT801 2+1 ARM touchscreen controllers
+ *
+ *  Copyright (c) 2015 Priit Laes <pl...@plaes.org>.
+ *
+ *  This code is based on goodix.c driver (c) 2014 Red Hat Inc,
+ *  various Android codedumps (c) 2010 - 2012 Goodix Technology
+ *  and cleanups done by Emilio López (turl) for linux-sunxi.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; version 2 of the License.
+ */
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/input/mt.h>
+
+struct gt801x_ts_data {
+       struct i2c_client *client;
+       struct input_dev *input_dev;
+       int abs_x_max;
+       int abs_y_max;
+       unsigned int max_touch_num;
+       unsigned int int_trigger_type;
+};
+
+#define GOODIX_MAX_HEIGHT              4096
+#define GOODIX_MAX_WIDTH               4096
+#define GOODIX_INT_TRIGGER             1
+#define GOODIX_MAX_CONTACTS            10
+#define MAX_CONTACTS_LOC       5
+#define RESOLUTION_LOC         1
+#define TRIGGER_LOC            6
+
+/* Register defines */
+#define GT801X_COOR_ADDR               0x01
+#define GT801X_CONFIG_DATA     0x65
+#define GT801X_REG_ID                  0xf0
+
+/* Device specific defines */
+#define GT801X_CONFIG_MAX_LENGTH       7
+#define GT801X_CONTACT_SIZE            5
+
+static const unsigned long goodix_irq_flags[] = {
+       IRQ_TYPE_EDGE_RISING,
+       IRQ_TYPE_EDGE_FALLING,
+       IRQ_TYPE_LEVEL_LOW,
+       IRQ_TYPE_LEVEL_HIGH,
+};
+
+/**
+ * gt801x_i2c_read - read data from a register of the i2c slave device.
+ *
+ * @client: i2c device.
+ * @reg: the register to read from.
+ * @buf: raw write data buffer.
+ * @len: length of the buffer to write
+ */
+static int gt801x_i2c_read(struct i2c_client *client,
+                          u8 reg, u8 *buf, int len)
+{
+       struct i2c_msg msgs[2];
+       int ret;
+
+       msgs[0].flags = 0;
+       msgs[0].addr  = client->addr;
+       msgs[0].len   = 1;
+       msgs[0].buf   = &reg;
+
+       msgs[1].flags = I2C_M_RD;
+       msgs[1].addr  = client->addr;
+       msgs[1].len   = len;
+       msgs[1].buf   = buf;
+
+       ret = i2c_transfer(client->adapter, msgs, 2);
+       return ret < 0 ? ret : (ret != ARRAY_SIZE(msgs) ? -EIO : 0);
+}
+
+/**
+ * gt801x_process_events - Process incoming events
+ *
+ * @ts: our gt801x_ts_data pointer
+ *
+ * Called when the IRQ is triggered. Read the current device state, and push
+ * the input events to the user space.
+ */
+static void gt801x_process_events(struct gt801x_ts_data *ts)
+{
+       u8 point_data[3 + GT801X_CONTACT_SIZE * GOODIX_MAX_CONTACTS];
+       u8 touch_map[GOODIX_MAX_CONTACTS] = {0};
+       int input_x, input_y, input_w;
+       u8 checksum = 0;
+       u16 touch_raw;
+       u8 touch_num;
+       int error;
+       int loc;
+       int i;
+
+       error = gt801x_i2c_read(ts->client, GT801X_COOR_ADDR,
+                               point_data, sizeof(point_data));
+       if (error) {
+               dev_err(&ts->client->dev, "I2C transfer error: %d\n", error);
+               return;
+       }
+
+       /* Fetch touch mapping bits */
+       touch_raw = get_unaligned_le16(&point_data[0]);
+       if (!touch_raw)
+               return;
+
+       /* Build touch map */
+       touch_num = 0;
+       for (i = 0; (touch_raw != 0) && (i < ts->max_touch_num); i++) {
+               if (touch_raw & 1)
+                       touch_map[touch_num++] = i;
+                       touch_raw >>= 1;
+       }
+
+       /* Calculate checksum */
+       for (i = 0; i < (touch_num*GT801X_CONTACT_SIZE + 3); i++)
+               checksum += point_data[i];
+       if (checksum != 0)
+               return;
+
+       /* Report touches */
+       for (i = 0; i < touch_num; i++) {
+               loc = 2 + GT801X_CONTACT_SIZE * i;
+               input_x = get_unaligned_be16(&point_data[loc]);
+               input_y = get_unaligned_be16(&point_data[loc + 2]);
+               input_w = point_data[loc + 4];
+
+               input_mt_slot(ts->input_dev, i);
+               input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER, true);
+               input_report_abs(ts->input_dev, ABS_MT_POSITION_X, input_x);
+               input_report_abs(ts->input_dev, ABS_MT_POSITION_Y, input_y);
+               input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR, input_w);
+               input_report_abs(ts->input_dev, ABS_MT_WIDTH_MAJOR, input_w);
+       }
+
+       input_mt_sync_frame(ts->input_dev);
+       input_sync(ts->input_dev);
+}
+
+/**
+ * gt801x_ts_irq_handler - The IRQ handler
+ *
+ * @irq: interrupt number.
+ * @dev_id: private data pointer.
+ */
+static irqreturn_t gt801x_ts_irq_handler(int irq, void *dev_id)
+{
+       gt801x_process_events((struct gt801x_ts_data *)dev_id);
+
+       return IRQ_HANDLED;
+}
+
+/**
+ * gt801x_read_config - Read the embedded configuration of the panel
+ *
+ * @ts: our gt801x_ts_data pointer
+ *
+ * Must be called during probe
+ */
+static void gt801x_read_config(struct gt801x_ts_data *ts)
+{
+       u8 config[GT801X_CONFIG_MAX_LENGTH];
+       int error;
+
+       error = gt801x_i2c_read(ts->client, GT801X_CONFIG_DATA,
+                               config,
+                               GT801X_CONFIG_MAX_LENGTH);
+       if (error) {
+               dev_warn(&ts->client->dev,
+                        "Error reading config (%d), using defaults\n",
+                        error);
+               ts->abs_x_max = GOODIX_MAX_WIDTH;
+               ts->abs_y_max = GOODIX_MAX_HEIGHT;
+               ts->int_trigger_type = GOODIX_INT_TRIGGER;
+               ts->max_touch_num = GOODIX_MAX_CONTACTS;
+               return;
+       }
+
+       ts->abs_x_max = get_unaligned_be16(&config[RESOLUTION_LOC]);
+       ts->abs_y_max = get_unaligned_be16(&config[RESOLUTION_LOC + 2]);
+       ts->int_trigger_type = config[TRIGGER_LOC] & 0x03;
+       ts->max_touch_num = config[MAX_CONTACTS_LOC] & 0x0f;
+       if (!ts->abs_x_max || !ts->abs_y_max || !ts->max_touch_num) {
+               dev_err(&ts->client->dev,
+                       "Invalid config, using defaults\n");
+               ts->abs_x_max = GOODIX_MAX_WIDTH;
+               ts->abs_y_max = GOODIX_MAX_HEIGHT;
+               ts->max_touch_num = GOODIX_MAX_CONTACTS;
+       }
+}
+
+/**
+ * gt801x_read_version - Read GT801 2+1 touchscreen version
+ *
+ * @client: the i2c client
+ * @version: output buffer containing the version on success
+ * @id: output buffer containing the id on success
+ */
+static int gt801x_read_version(struct i2c_client *client, u16 *version, u16 
*id)
+{
+       int error;
+       u8 buf[16];
+
+       error = gt801x_i2c_read(client, GT801X_REG_ID, buf, sizeof(buf));
+       if (error) {
+               dev_err(&client->dev, "read version failed: %d\n", error);
+               return error;
+       }
+       /* TODO: version info contains 'GT801NI_3R15_1AV' */
+       print_hex_dump_bytes("", DUMP_PREFIX_NONE, buf, ARRAY_SIZE(buf));
+       *id = 0x802;
+       *version = 0x15;
+       dev_info(&client->dev, "ID %d, version: %04x\n", *id, *version);
+       return 0;
+}
+
+/**
+ * gt801x_i2c_test - I2C test function to check if the device answers.
+ *
+ * @client: the i2c client
+ */
+static int gt801x_i2c_test(struct i2c_client *client)
+{
+       int retry = 0;
+       int error;
+       u8 test;
+
+       while (retry++ < 2) {
+               error = gt801x_i2c_read(client, GT801X_CONFIG_DATA,
+                                       &test, 1);
+               if (!error)
+                       return 0;
+
+               dev_err(&client->dev, "i2c test failed attempt %d: %d\n",
+                       retry, error);
+               msleep(20);
+       }
+
+       return error;
+}
+
+/**
+ * gt801x_request_input_dev - Allocate, populate and register the input device
+ *
+ * @ts: our gt801x_ts_data pointer
+ * @version: device firmware version
+ * @id: device ID
+ *
+ * Must be called during probe
+ */
+static int gt801x_request_input_dev(struct gt801x_ts_data *ts,
+                                       u16 version, u16 id)
+{
+       int error;
+
+       ts->input_dev = devm_input_allocate_device(&ts->client->dev);
+       if (!ts->input_dev) {
+               dev_err(&ts->client->dev, "Failed to allocate input device.");
+               return -ENOMEM;
+       }
+
+       input_set_abs_params(ts->input_dev, ABS_MT_POSITION_X,
+                            0, ts->abs_x_max, 0, 0);
+       input_set_abs_params(ts->input_dev, ABS_MT_POSITION_Y,
+                            0, ts->abs_y_max, 0, 0);
+       input_set_abs_params(ts->input_dev, ABS_MT_WIDTH_MAJOR, 0, 255, 0, 0);
+       input_set_abs_params(ts->input_dev, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
+
+       input_mt_init_slots(ts->input_dev, ts->max_touch_num,
+                           INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+
+       ts->input_dev->name = "Goodix Capacitive TouchScreen (GT801 2+1)";
+       ts->input_dev->phys = "input/ts";
+       ts->input_dev->id.bustype = BUS_I2C;
+       ts->input_dev->id.vendor = 0x0416;
+       ts->input_dev->id.product = id;
+       ts->input_dev->id.version = version;
+
+       error = input_register_device(ts->input_dev);
+       if (error) {
+               dev_err(&ts->client->dev,
+                       "Failed to register input device: %d", error);
+               return error;
+       }
+
+       return 0;
+}
+
+static int gt801x_ts_probe(struct i2c_client *client,
+                          const struct i2c_device_id *id)
+{
+       struct gt801x_ts_data *ts;
+       unsigned long irq_flags;
+       int error;
+       u16 version_info, id_info;
+
+       dev_dbg(&client->dev, "I2C Address: 0x%02x\n", client->addr);
+
+       if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+               dev_err(&client->dev, "I2C check functionality failed.\n");
+               return -ENXIO;
+       }
+
+       ts = devm_kzalloc(&client->dev, sizeof(*ts), GFP_KERNEL);
+       if (!ts)
+               return -ENOMEM;
+
+       ts->client = client;
+       i2c_set_clientdata(client, ts);
+
+       error = gt801x_i2c_test(client);
+       if (error) {
+               dev_err(&client->dev, "I2C communication failure: %d\n", error);
+               return error;
+       }
+
+       error = gt801x_read_version(client, &version_info, &id_info);
+       if (error) {
+               dev_err(&client->dev, "Read version failed.\n");
+               return error;
+       }
+
+       gt801x_read_config(ts);
+
+       error = gt801x_request_input_dev(ts, version_info, id_info);
+       if (error)
+               return error;
+
+       irq_flags = goodix_irq_flags[ts->int_trigger_type] | IRQF_ONESHOT;
+       error = devm_request_threaded_irq(&ts->client->dev, client->irq,
+                                         NULL, gt801x_ts_irq_handler,
+                                         irq_flags, client->name, ts);
+       if (error) {
+               dev_err(&client->dev, "request IRQ failed: %d\n", error);
+               return error;
+       }
+
+       return 0;
+}
+
+static const struct i2c_device_id gt801x_ts_id[] = {
+       { "GDIX1001:00", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, gt801x_ts_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id gt801x_of_match[] = {
+       { .compatible = "goodix,gt801_2plus1" },
+       { }
+};
+MODULE_DEVICE_TABLE(of, gt801x_of_match);
+#endif
+
+static struct i2c_driver gt801x_ts_driver = {
+       .probe = gt801x_ts_probe,
+       .id_table = gt801x_ts_id,
+       .driver = {
+               .name = "Goodix-TS",
+               .of_match_table = of_match_ptr(gt801x_of_match),
+       },
+};
+module_i2c_driver(gt801x_ts_driver);
+
+MODULE_AUTHOR("Priit Laes <pl...@plaes.org>");
+MODULE_DESCRIPTION("Goodix GT801 2+1 touchscreen driver");
+MODULE_LICENSE("GPL v2");
-- 
2.6.3

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