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>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index d9099b15b472..22325ed24139 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -409,6 +409,9 @@ static inline bool acpi_driver_match_device(struct device *dev,
 	return !!acpi_match_device(drv->acpi_match_table, dev);
 }
 
+int acpi_device_uevent_modalias(struct device *, struct kobj_uevent_env *);
+int acpi_device_modalias(struct device *, char *, int);
+
 #define ACPI_PTR(_ptr)	(_ptr)
 
 #else	/* !CONFIG_ACPI */
@@ -488,6 +491,18 @@ static inline bool acpi_driver_match_device(struct device *dev,
 	return false;
 }
 
+static inline int acpi_device_uevent_modalias(struct device *dev,
+				struct kobj_uevent_env *env)
+{
+	return -ENODEV;
+}
+
+static inline int acpi_device_modalias(struct device *dev,
+				char *buf, int size)
+{
+	return -ENODEV;
+}
+
 #define ACPI_PTR(_ptr)	(NULL)
 
 #endif	/* !CONFIG_ACPI */