On 10/14/2013 05:10 PM, Zhang Rui wrote:
> 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:pdev->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:client->name).
>
> 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 driver.
>
> So this is a problem that will affect us the day when the ACPI bus
> is removed from device model.
>
> This patch introduces a new function to exporting ACPI ids as the
> module_alias, for the ACPI enumerate devices.
>
> For any drivers using MODULE_DEVICE_TALBE(acpi, blabla), the uevent file
> of its associated device must be fixed by invoking this function.
>
> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> ---
> drivers/acpi/scan.c | 24 ++++++++++++++++++++++++
> include/linux/acpi.h | 8 ++++++++
> 2 files changed, 32 insertions(+)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 407ad13..db6f879 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -111,6 +111,30 @@ static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
> return len;
> }
>
> +int acpi_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
> +{
> + struct acpi_device *acpi_dev;
> + int result;
> + int len;
> +
> + result = acpi_bus_get_device(ACPI_HANDLE(dev), &acpi_dev);
> + if (result)
> + return result;
> +
> + if (list_empty(&acpi_dev->pnp.ids))
> + return 0;
> +
> + if (add_uevent_var(env, "MODALIAS="))
> + return -ENOMEM;
> + len = create_modalias(acpi_dev, &env->buf[env->buflen - 1],
> + sizeof(env->buf) - env->buflen);
> + if (len >= (sizeof(env->buf) - env->buflen))
> + return -ENOMEM;
> + env->buflen += len;
> + return 0;
> +}
> +EXPORT_SYMBOL(acpi_device_uevent_modalias);
Looks like this function shares a lot with the existing
acpi_device_uevent, so perhaps worth making some resue of the exising
code? e.g. seperate the common code into a function and then have the
two functions call it.
-Aaron
> +
> static ssize_t
> acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, char *buf) {
> struct acpi_device *acpi_dev = to_acpi_device(dev);
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index a5db4ae..117fa26 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -401,6 +401,8 @@ 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 *);
> +
> #define ACPI_PTR(_ptr) (_ptr)
>
> #else /* !CONFIG_ACPI */
> @@ -471,6 +473,12 @@ 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;
> +}
> +
> #define ACPI_PTR(_ptr) (NULL)
>
> #endif /* !CONFIG_ACPI */
>
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