Re: [PATCH v5 03/12] ACPI: Allow drivers to match using Device Tree compatible property

[Grant Likely]

On Fri, 17 Oct 2014 14:05:59 +0200
, "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
 wrote:
> From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> 
> We have lots of existing Device Tree enabled drivers and allocating
> separate _HID for each is not feasible. Instead we allocate special _HID
> "PRP0001" that means that the match should be done using Device Tree
> compatible property using driver's .of_match_table instead if the driver
> is missing .acpi_match_table.

(Not a critique of this patch, but merely a helpful comment; my previous
ack remains intact) :-)

It would be useful for the code to point at some document that describes
the semantics of the PRP0001 binding.

g.

> 
> If there is a need to distinguish from where the device is enumerated
> (DT/ACPI) driver can check dev->of_node or ACPI_COMPATION(dev).
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Reviewed-by: Grant Likely <grant.likely@xxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>  drivers/acpi/property.c | 34 +++++++++++++++++
>  drivers/acpi/scan.c     | 97 +++++++++++++++++++++++++++++++++++++++++++------
>  include/acpi/acpi_bus.h |  1 +
>  include/linux/acpi.h    |  8 +---
>  4 files changed, 123 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> index 680f7f1..ff53eb8 100644
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -76,6 +76,37 @@ static bool acpi_properties_format_valid(const union acpi_object *properties)
>  	return true;
>  }
>  
> +static void acpi_init_of_compatible(struct acpi_device *adev)
> +{
> +	const union acpi_object *of_compatible;
> +	struct acpi_hardware_id *hwid;
> +	bool acpi_of = false;
> +
> +	/*
> +	 * Check if the special PRP0001 ACPI ID is present and in that
> +	 * case we fill in Device Tree compatible properties for this
> +	 * device.
> +	 */
> +	list_for_each_entry(hwid, &adev->pnp.ids, list) {
> +		if (!strcmp(hwid->id, "PRP0001")) {
> +			acpi_of = true;
> +			break;
> +		}
> +	}
> +
> +	if (!acpi_of)
> +		return;
> +
> +	if (acpi_dev_get_property_array(adev, "compatible", ACPI_TYPE_STRING,
> +					&of_compatible)) {
> +		acpi_handle_warn(adev->handle,
> +				 "PRP0001 requires compatible property\n");
> +		return;
> +	}
> +
> +	adev->data.of_compatible = of_compatible;
> +}
> +
>  void acpi_init_properties(struct acpi_device *adev)
>  {
>  	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
> @@ -119,6 +150,8 @@ void acpi_init_properties(struct acpi_device *adev)
>  
>  		adev->data.pointer = buf.pointer;
>  		adev->data.properties = properties;
> +
> +		acpi_init_of_compatible(adev);
>  		return;
>  	}
>  
> @@ -130,6 +163,7 @@ void acpi_init_properties(struct acpi_device *adev)
>  void acpi_free_properties(struct acpi_device *adev)
>  {
>  	ACPI_FREE((void *)adev->data.pointer);
> +	adev->data.of_compatible = NULL;
>  	adev->data.pointer = NULL;
>  	adev->data.properties = NULL;
>  }
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 1979ab3..bc999f1 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -124,17 +124,51 @@ static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
>  	if (list_empty(&acpi_dev->pnp.ids))
>  		return 0;
>  
> -	len = snprintf(modalias, size, "acpi:");
> -	size -= len;
> -
> -	list_for_each_entry(id, &acpi_dev->pnp.ids, list) {
> -		count = snprintf(&modalias[len], size, "%s:", id->id);
> -		if (count < 0)
> -			return -EINVAL;
> -		if (count >= size)
> -			return -ENOMEM;
> -		len += count;
> -		size -= count;
> +	/*
> +	 * If the device has PRP0001 we expose DT compatible modalias
> +	 * instead in form of of:NnameTCcompatible.
> +	 */
> +	if (acpi_dev->data.of_compatible) {
> +		struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
> +		const union acpi_object *of_compatible, *obj;
> +		char *c;
> +		int i;
> +
> +		acpi_get_name(acpi_dev->handle, ACPI_SINGLE_NAME, &buf);
> +		/* DT strings are all in lower case */
> +		for (c = buf.pointer; *c != '\0'; c++)
> +			*c = tolower(*c);
> +
> +		len = snprintf(modalias, size, "of:N%sT", (char *)buf.pointer);
> +		ACPI_FREE(buf.pointer);
> +
> +		of_compatible = acpi_dev->data.of_compatible;
> +		for (i = 0; i < of_compatible->package.count; i++) {
> +			obj = &of_compatible->package.elements[i];
> +
> +			count = snprintf(&modalias[len], size, "C%s",
> +					 obj->string.pointer);
> +			if (count < 0)
> +				return -EINVAL;
> +			if (count >= size)
> +				return -ENOMEM;
> +
> +			len += count;
> +			size -= count;
> +		}
> +	} else {
> +		len = snprintf(modalias, size, "acpi:");
> +		size -= len;
> +
> +		list_for_each_entry(id, &acpi_dev->pnp.ids, list) {
> +			count = snprintf(&modalias[len], size, "%s:", id->id);
> +			if (count < 0)
> +				return -EINVAL;
> +			if (count >= size)
> +				return -ENOMEM;
> +			len += count;
> +			size -= count;
> +		}
>  	}
>  
>  	modalias[len] = '\0';
> @@ -864,6 +898,47 @@ int acpi_match_device_ids(struct acpi_device *device,
>  }
>  EXPORT_SYMBOL(acpi_match_device_ids);
>  
> +/* Performs match against special "PRP0001" shoehorn ACPI ID */
> +static bool acpi_of_driver_match_device(struct device *dev,
> +					const struct device_driver *drv)
> +{
> +	const union acpi_object *of_compatible;
> +	struct acpi_device *adev;
> +	int i;
> +
> +	adev = ACPI_COMPANION(dev);
> +	if (!adev)
> +		return false;
> +
> +	of_compatible = adev->data.of_compatible;
> +	if (!drv->of_match_table || !of_compatible)
> +		return false;
> +
> +	/* Now we can look for the driver DT compatible strings */
> +	for (i = 0; i < of_compatible->package.count; i++) {
> +		const struct of_device_id *id;
> +		const union acpi_object *obj;
> +
> +		obj = &of_compatible->package.elements[i];
> +
> +		for (id = drv->of_match_table; id->compatible[0]; id++)
> +			if (!strcasecmp(obj->string.pointer, id->compatible))
> +				return true;
> +	}
> +
> +	return false;
> +}
> +
> +bool acpi_driver_match_device(struct device *dev,
> +			      const struct device_driver *drv)
> +{
> +	if (!drv->acpi_match_table)
> +		return acpi_of_driver_match_device(dev, drv);
> +
> +	return !!acpi_match_device(drv->acpi_match_table, dev);
> +}
> +EXPORT_SYMBOL_GPL(acpi_driver_match_device);
> +
>  static void acpi_free_power_resources_lists(struct acpi_device *device)
>  {
>  	int i;
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index f9734fa..98cd723 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -341,6 +341,7 @@ struct acpi_device_physical_node {
>  struct acpi_device_data {
>  	const union acpi_object *pointer;
>  	const union acpi_object *properties;
> +	const union acpi_object *of_compatible;
>  };
>  
>  /* Device */
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 18c1bc3..11aa6b8 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -424,12 +424,8 @@ extern int acpi_nvs_for_each_region(int (*func)(__u64, __u64, void *),
>  const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,
>  					       const struct device *dev);
>  
> -static inline bool acpi_driver_match_device(struct device *dev,
> -					    const struct device_driver *drv)
> -{
> -	return !!acpi_match_device(drv->acpi_match_table, dev);
> -}
> -
> +extern bool acpi_driver_match_device(struct device *dev,
> +				     const struct device_driver *drv);
>  int acpi_device_uevent_modalias(struct device *, struct kobj_uevent_env *);
>  int acpi_device_modalias(struct device *, char *, int);
>  
> -- 
> 1.9.3
> 
> 

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