tree 7ff8db97b03fa018bd4d7628186e35523a82ac04
parent 3d8e00909df96c2d3eace3996748be9c0a437e5a
author Zhang Rui <rui.zhang@intel.com> 1389689196 +0800
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1389910240 +0100

ACPI: add module autoloading support for ACPI enumerated devices

An ACPI enumerated device may have its compatible id strings.

To support the compatible ACPI ids (acpi_device->pnp.ids),
we introduced acpi_driver_match_device() to match
the driver->acpi_match_table and acpi_device->pnp.ids.

For those drivers, MODULE_DEVICE_TABLE(acpi, xxx) is used to
exports the driver module alias in the format of
"acpi:device_compatible_ids".
But in the mean time, the current code does not export the
ACPI compatible strings as part of the module_alias for the
ACPI enumerated devices, which will break the module autoloading.

Take the following piece of code for example,
static const struct acpi_device_id xxx_acpi_match[] = {
        { "INTABCD", 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, xxx_acpi_match);

If this piece of code is used in a platform driver for
an ACPI enumerated platform device, the platform driver module_alias
is "acpi:INTABCD", but the uevent attribute of its platform device node
is "platform:INTABCD:00" (PREFIX:platform_device->name).
If this piece of code is used in an i2c driver for an ACPI enumerated
i2c device, the i2c driver module_alias is "acpi:INTABCD", but
the uevent of its i2c device node is "i2c:INTABCD:00" (PREFIX:i2c_client->name).
If this piece of code is used in an spi driver for an ACPI enumerated
spi device, the spi driver module_alias is "acpi:INTABCD", but
the uevent of its spi device node is "spi:INTABCD" (PREFIX:spi_device->modalias).

The reason why the module autoloading is not broken for now is that
the uevent file of the ACPI device node is "acpi:INTABCD".
Thus it is the ACPI device node creation that loads the platform/i2c/spi driver.

So this is a problem that will affect us the day when the ACPI bus
is removed from device model.

This patch introduces two new APIs,
one for exporting ACPI ids in uevent MODALIAS field,
and another for exporting ACPI ids in device' modalias sysfs attribute.

For any bus that supports ACPI enumerated devices, it needs to invoke
these two functions for their uevent and modalias attribute.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>