Hi Mika,

On Fri, May 06, 2016 at 08:22:16AM +0300, mika.pentt...@nextfour.com wrote:
> From: Mika Penttilä <mika.pentt...@nextfour.com>
> 
> Multitouch protocol B support.
> 
> 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.pentt...@nextfour.com>
> Acked-by: Tammy Tseng <tammy_ts...@sis.com>
> Acked-by: Yuger Yu <yuger...@sis.com>
> ---
>  drivers/input/touchscreen/Kconfig   |  12 +
>  drivers/input/touchscreen/Makefile  |   1 +
>  drivers/input/touchscreen/sis_i2c.c | 461 
> ++++++++++++++++++++++++++++++++++++
>  3 files changed, 474 insertions(+)
>  create mode 100644 drivers/input/touchscreen/sis_i2c.c
> 
> diff --git a/drivers/input/touchscreen/Kconfig 
> b/drivers/input/touchscreen/Kconfig
> index 8ecdc38..8f06ae7 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -1155,4 +1155,16 @@ 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 f42975e..0839e99 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -63,6 +63,7 @@ obj-$(CONFIG_TOUCHSCREEN_PCAP)              += pcap_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_PENMOUNT)   += penmount.o
>  obj-$(CONFIG_TOUCHSCREEN_PIXCIR)     += pixcir_i2c_ts.o
>  obj-$(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..f1b66fa
> --- /dev/null
> +++ b/drivers/input/touchscreen/sis_i2c.c
> @@ -0,0 +1,461 @@
> +/* drivers/input/touchscreen/sis_i2c.c
> + *  - I2C Touch panel driver for SiS 9200 family
> + *
> + * Copyright (C) 2011 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/module.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/input.h>
> +#include <linux/input/mt.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>

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 <mika.pentt...@nextfour.com>

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

Signed-off-by: Mika Penttilä <mika.pentt...@nextfour.com>
Acked-by: Tammy Tseng <tammy_ts...@sis.com>
Acked-by: Yuger Yu <yuger...@sis.com>
Patchwork-Id: 9029121
Signed-off-by: Dmitry Torokhov <dmitry.torok...@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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