i2c: core: Allow getting ACPI info by index

Modify struct i2c_acpi_lookup and i2c_acpi_fill_info() to allow
using them to get the info from a certain index in the ACPI-resource
list rather then taking the first I2cSerialBus resource.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/i2c-core.c

@@ -112,6 +112,8 @@ struct i2c_acpi_lookup {
 	acpi_handle adapter_handle;
 	acpi_handle device_handle;
 	acpi_handle search_handle;
+	int n;
+	int index;
 	u32 speed;
 	u32 min_speed;
 };
@@ -130,6 +132,9 @@ static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data)
 	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
 		return 1;
 
+	if (lookup->index != -1 && lookup->n++ != lookup->index)
+		return 1;
+
 	status = acpi_get_handle(lookup->device_handle,
 				 sb->resource_source.string_ptr,
 				 &lookup->adapter_handle);
@@ -182,6 +187,7 @@ static int i2c_acpi_get_info(struct acpi_device *adev,
 
 	memset(&lookup, 0, sizeof(lookup));
 	lookup.info = info;
+	lookup.index = -1;
 
 	ret = i2c_acpi_do_lookup(adev, &lookup);
 	if (ret)
@@ -328,6 +334,7 @@ u32 i2c_acpi_find_bus_speed(struct device *dev)
 	lookup.search_handle = ACPI_HANDLE(dev);
 	lookup.min_speed = UINT_MAX;
 	lookup.info = &dummy;
+	lookup.index = -1;
 
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     I2C_ACPI_MAX_SCAN_DEPTH,