ACPI: fix module autoloading for ACPI enumerated devices

ACPI enumerated devices has ACPI style _HID and _CID strings,
all of these strings can be used for both driver loading and matching.

Currently, in Platform, I2C and SPI bus, the ACPI style driver matching
is supported by invoking acpi_driver_match_device() in bus .match() callback.
But, the module autoloading is still broken.

For example, there is any ACPI device with _HID "INTABCD" that is
enumerated to platform bus, and we have a driver that can probe it.

The driver exports its module_alias as "acpi:INTABCD" use the following code
static const struct acpi_device_id xxx_acpi_match[] = {
        { "INTABCD", 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, xxx_acpi_match);

But, unfortunately, the device' modalias is shown as "platform:INTABCD:00",
please refer to modalias_show() and platform_uevent() in
drivers/base/platform.c.
This results in that the driver will not be loaded automatically when the
device node is created, because their modalias do not match.

This also applies to I2C and SPI bus.

With this patch, the device' modalias will be shown as "acpi:INTABCD" as well.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Mark Brown <broonie@linaro.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index d74c0b34248..c4c5588ec0f 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -104,6 +104,11 @@ static int i2c_device_match(struct device *dev, struct device_driver *drv)
 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
 	struct i2c_client	*client = to_i2c_client(dev);
+	int rc;
+
+	rc = acpi_device_uevent_modalias(dev, env);
+	if (rc != -ENODEV)
+		return rc;
 
 	if (add_uevent_var(env, "MODALIAS=%s%s",
 			   I2C_MODULE_PREFIX, client->name))
@@ -409,6 +414,12 @@ static ssize_t
 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev);
+	int len;
+
+	len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
+	if (len != -ENODEV)
+		return len;
+
 	return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
 }