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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>
This commit is contained in:
Hans de Goede 2020-04-28 19:29:18 +02:00 committed by Jonathan Cameron
parent b885d0fa67
commit c1e62062ff
1 changed files with 22 additions and 0 deletions
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22
drivers/iio/light/cm32181.c
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@ -52,6 +52,8 @@
#define CM32181_CALIBSCALE_RESOLUTION 1000
#define MLUX_PER_LUX 1000
#define SMBUS_ALERT_RESPONSE_ADDRESS 0x0c
static const u8 cm32181_reg[CM32181_CONF_REG_NUM] = {
CM32181_REG_ADDR_CMD,
};
@ -336,6 +338,26 @@ static int cm32181_probe(struct i2c_client *client)
if (!indio_dev)
return -ENOMEM;
/*
* Some ACPI systems list 2 I2C resources for the CM3218 sensor, the
* SMBus Alert Response Address (ARA, 0x0c) and the actual I2C address.
* 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.
*/
if (ACPI_HANDLE(dev) && client->addr == SMBUS_ALERT_RESPONSE_ADDRESS) {
struct i2c_board_info board_info = { .type = "dummy" };
i2c_smbus_read_byte(client);
client = i2c_acpi_new_device(dev, 1, &board_info);
if (IS_ERR(client))
return PTR_ERR(client);
}
cm32181 = iio_priv(indio_dev);
cm32181->client = client;