iio: light: cm32181: Handle CM3218 ACPI devices with 2 I2C resources

Some ACPI systems list 2 I2C resources for the CM3218 sensor. On these
systems the first I2cSerialBus ACPI-resource points to the SMBus Alert
Response Address (ARA, 0x0c) and the second I2cSerialBus ACPI-resource
points to the actual CM3218 sensor address:

 Method (_CRS, 0, NotSerialized)  // _CRS: Current Resource Settings
 {
     Name (SBUF, ResourceTemplate ()
     {
         I2cSerialBusV2 (0x000C, ControllerInitiated, 0x00061A80,
             AddressingMode7Bit, "\\_SB.I2C3",
             0x00, ResourceConsumer, , Exclusive,
             )
         I2cSerialBusV2 (0x0048, ControllerInitiated, 0x00061A80,
             AddressingMode7Bit, "\\_SB.I2C3",
             0x00, ResourceConsumer, , Exclusive,
             )
         Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive, ,, )
         {
             0x00000033,
         }
     })
     Return (SBUF) /* \_SB_.I2C3.ALSD._CRS.SBUF */
 }

Detect this and take the following step to deal with it:

1. When a SMBus Alert capable sensor has an Alert asserted, it will
   not respond on its actual I2C address. Read a byte from the ARA
   to clear any pending Alerts.

2. Create a "dummy" client for the actual I2C address and
   use that client to communicate with the sensor.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

0 files changed, 0 insertions, 0 deletions