On Thu, Dec 1, 2016 at 9:29 AM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> Add acpi_resource_consumer(). This takes a struct resource and searches
> the ACPI namespace for a device whose current resource settings (_CRS)
> includes the resource. It returns the device if it exists, or NULL if no
> device uses the resource.
>
> If more than one device uses the resource (this may happen in the case of
> bridges), acpi_resource_consumer() returns the first one found by
> acpi_get_devices() in its modified depth-first walk of the namespace.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
(this patch should have been CCed to linux-acpi too, however).
> ---
> drivers/acpi/resource.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/acpi.h | 7 ++++++
> 2 files changed, 64 insertions(+)
>
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index 56241eb..cb57962 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -664,3 +664,60 @@ int acpi_dev_filter_resource_type(struct acpi_resource *ares,
> return (type & types) ? 0 : 1;
> }
> EXPORT_SYMBOL_GPL(acpi_dev_filter_resource_type);
> +
> +static int acpi_dev_consumes_res(struct acpi_device *adev, struct resource *res)
> +{
> + struct list_head resource_list;
> + struct resource_entry *rentry;
> + int ret, found = 0;
> +
> + INIT_LIST_HEAD(&resource_list);
> + ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
> + if (ret < 0)
> + return 0;
> +
> + list_for_each_entry(rentry, &resource_list, node) {
> + if (resource_contains(rentry->res, res)) {
> + found = 1;
> + break;
> + }
> +
> + }
> +
> + acpi_dev_free_resource_list(&resource_list);
> + return found;
> +}
> +
> +static acpi_status acpi_res_consumer_cb(acpi_handle handle, u32 depth,
> + void *context, void **ret)
> +{
> + struct resource *res = context;
> + struct acpi_device **consumer = (struct acpi_device **) ret;
> + struct acpi_device *adev;
> +
> + if (acpi_bus_get_device(handle, &adev))
> + return AE_OK;
> +
> + if (acpi_dev_consumes_res(adev, res)) {
> + *consumer = adev;
> + return AE_CTRL_TERMINATE;
> + }
> +
> + return AE_OK;
> +}
> +
> +/**
> + * acpi_resource_consumer - Find the ACPI device that consumes @res.
> + * @res: Resource to search for.
> + *
> + * Search the current resource settings (_CRS) of every ACPI device node
> + * for @res. If we find an ACPI device whose _CRS includes @res, return
> + * it. Otherwise, return NULL.
> + */
> +struct acpi_device *acpi_resource_consumer(struct resource *res)
> +{
> + struct acpi_device *consumer = NULL;
> +
> + acpi_get_devices(NULL, acpi_res_consumer_cb, res, (void **) &consumer);
> + return consumer;
> +}
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index ddbeda6..b00ad73 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -419,6 +419,8 @@ static inline int acpi_dev_filter_resource_type_cb(struct acpi_resource *ares,
> return acpi_dev_filter_resource_type(ares, (unsigned long)arg);
> }
>
> +struct acpi_device *acpi_resource_consumer(struct resource *res);
> +
> int acpi_check_resource_conflict(const struct resource *res);
>
> int acpi_check_region(resource_size_t start, resource_size_t n,
> @@ -762,6 +764,11 @@ static inline int acpi_reconfig_notifier_unregister(struct notifier_block *nb)
> return -EINVAL;
> }
>
> +static inline struct acpi_device *acpi_resource_consumer(struct resource *res)
> +{
> + return NULL;
> +}
> +
> #endif /* !CONFIG_ACPI */
>
> #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
>
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