• Irina Tirdea's avatar
    Input: goodix - reset device at init · ec6e1b40
    Irina Tirdea authored
    After power on, it is recommended that the driver resets the device.
    The reset procedure timing is described in the datasheet and is used
    at device init (before writing device configuration) and
    for power management. It is a sequence of setting the interrupt
    and reset pins high/low at specific timing intervals. This procedure
    also includes setting the slave address to the one specified in the
    ACPI/device tree.
    
    This is based on Goodix datasheets for GT911 and GT9271 and on Goodix
    driver gt9xx.c for Android (publicly available in Android kernel
    trees for various devices).
    
    For reset the driver needs to control the interrupt and
    reset gpio pins (configured through ACPI/device tree). For devices
    that do not have the gpio pins properly declared, the functionality
    depending on these pins will not be available, but the device can still
    be used with basic functionality.
    
    For both device tree and ACPI, the interrupt gpio pin configuration is
    read from the "irq-gpios" property and the reset pin configuration is
    read from the "reset-gpios" property. For ACPI 5.1, named properties
    can be specified using the _DSD section. This functionality will not be
    available for devices that use indexed gpio pins declared in the _CRS
    section (we need to provide backward compatibility with devices
    that do not support using the interrupt gpio pin as output).
    
    For ACPI, the pins can be specified using ACPI 5.1:
    Device (STAC)
    {
        Name (_HID, "GDIX1001")
        ...
    
        Method (_CRS, 0, Serialized)
        {
            Name (RBUF, ResourceTemplate ()
            {
                I2cSerialBus (0x0014, ControllerInitiated, 0x00061A80,
                    AddressingMode7Bit, "\\I2C0",
                    0x00, ResourceConsumer, ,
                    )
    
                GpioInt (Edge, ActiveHigh, Exclusive, PullNone, 0x0000,
                    "\\I2C0", 0x00, ResourceConsumer, ,
                     )
                     {   // Pin list
                         0
                     }
    
                GpioIo (Exclusive, PullDown, 0x0000, 0x0000,
                    IoRestrictionOutputOnly, "\\I2C0", 0x00,
                    ResourceConsumer, ,
                    )
                    {
                         1
                    }
            })
            Return (RBUF)
        }
    
        Name (_DSD,  Package ()
        {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package ()
            {
                Package (2) {"irq-gpios", Package() {^STAC, 0, 0, 0 }},
                Package (2) {"reset-gpios", Package() {^STAC, 1, 0, 0 }},
                ...
            }
        }
    Signed-off-by: default avatarOctavian Purdila <octavian.purdila@intel.com>
    Signed-off-by: default avatarIrina Tirdea <irina.tirdea@intel.com>
    Acked-by: default avatarRob Herring <robh@kernel.org>
    Acked-by: default avatarBastien Nocera <hadess@hadess.net>
    Tested-by: default avatarBastien Nocera <hadess@hadess.net>
    Tested-by: default avatarAleksei Mamlin <mamlinav@gmail.com>
    Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
    ec6e1b40
goodix.txt 882 Bytes