i2c: add ACPI support for I2C mux ports

Although I2C mux devices are easily enumerated using ACPI (_HID/_CID or
device property compatible string match), enumerating I2C client devices
connected through an I2C mux needs a little extra work.

This change implements a method for describing an I2C device hierarchy that
includes mux devices by using an ACPI Device() for each mux channel along
with an _ADR to set the channel number for the device.  See
Documentation/acpi/i2c-muxes.txt for a simple example.

To make this work the ismt, i801, and designware pci/platform devs now
share an ACPI companion with their I2C adapter dev similar to how it's done
in OF.  This is done on the assumption that power management functions will
not be called directly on the I2C dev that is sharing the ACPI node.

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Dustin Byford <dustin@cumulusnetworks.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3a4c54ef290d..5897fdb2480d 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -156,7 +156,7 @@ static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
         info.fwnode = acpi_fwnode_handle(adev);
 
         memset(&lookup, 0, sizeof(lookup));
-        lookup.adapter_handle = ACPI_HANDLE(adapter->dev.parent);
+        lookup.adapter_handle = ACPI_HANDLE(&adapter->dev);
         lookup.device_handle = handle;
         lookup.info = &info;
 
@@ -212,7 +212,7 @@ static void acpi_i2c_register_devices(struct i2c_adapter *adap)
 {
         acpi_status status;
 
-        if (!adap->dev.parent || !has_acpi_companion(adap->dev.parent))
+        if (!has_acpi_companion(&adap->dev))
                 return;
 
         status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,