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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Thu, 1 Dec 2016 14:17:20 +0100
Message-ID: <CAJZ5v0hB61=17Fbf=2-K=zaRmMZkY3NVxMPHNwfF9Nr6=ey+-g@mail.gmail.com>
Subject: Re: [PATCH v10 01/12] ACPI: Add acpi_resource_consumer() to find
 device that claims a resource
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Linux PCI <linux-pci@vger.kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Gabriele Paoloni <gabriele.paoloni@huawei.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>, Tomasz Nowicki <tn@semihalf.com>, Duc Dang <dhdang@apm.com>,
	Sinan Kaya <okaya@codeaurora.org>, Christopher Covington <cov@codeaurora.org>,
	Dongdong Liu <liudongdong3@huawei.com>
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List-ID: <linux-pci.vger.kernel.org>

On Thu, Dec 1, 2016 at 9:29 AM, Bjorn Helgaas <helgaas@kernel.org> wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
>
> 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@google.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

(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
>