On Mon, 20 Sep 2021 07:41:31 +0100,
Kishon Vijay Abraham I <kishon@xxxxxx> wrote:
>
> Add two arguments to pci_walk_bus() [requestorID and mask], and add
> support in pci_walk_bus() to invoke the *callback* only for devices
> whose RequestorID after applying *mask* matches with *requestorID*
> passed as argument.
>
> This is done in preparation for calculating the total number of
> interrupt vectors that has to be supported by a specific GIC ITS device ID,
> specifically when "msi-map-mask" is populated in device tree.
>
> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> ---
> drivers/pci/bus.c | 13 +++++++++----
> include/linux/pci.h | 7 +++++--
> 2 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 3cef835b375f..e381e639ceaa 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -358,10 +358,12 @@ void pci_bus_add_devices(const struct pci_bus *bus)
> }
> EXPORT_SYMBOL(pci_bus_add_devices);
>
> -/** pci_walk_bus - walk devices on/under bus, calling callback.
> +/** __pci_walk_bus - walk devices on/under bus matching requestor ID, calling callback.
> * @top bus whose devices should be walked
> * @cb callback to be called for each device found
> * @userdata arbitrary pointer to be passed to callback.
> + * @rid Requestor ID that has to be matched for the callback to be invoked
> + * @mask Mask that has to be applied to pci_dev_id(), before compating it with @rid
> *
> * Walk the given bus, including any bridged devices
> * on buses under this bus. Call the provided callback
> @@ -371,8 +373,8 @@ EXPORT_SYMBOL(pci_bus_add_devices);
> * other than 0, we break out.
> *
> */
> -void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> - void *userdata)
> +void __pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> + void *userdata, u32 rid, u32 mask)
> {
> struct pci_dev *dev;
> struct pci_bus *bus;
> @@ -399,13 +401,16 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> } else
> next = dev->bus_list.next;
>
> + if (mask != 0xffff && ((pci_dev_id(dev) & mask) != rid))
Why the check for the mask? I also wonder whether the mask should apply
to the rid as well:
if ((pci_dev_id(dev) & mask) != (rid & mask))
> + continue;
> +
> retval = cb(dev, userdata);
> if (retval)
> break;
> }
> up_read(&pci_bus_sem);
> }
> -EXPORT_SYMBOL_GPL(pci_walk_bus);
> +EXPORT_SYMBOL_GPL(__pci_walk_bus);
>
> struct pci_bus *pci_bus_get(struct pci_bus *bus)
> {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index cd8aa6fce204..8500fec56e50 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1473,14 +1473,17 @@ const struct pci_device_id *pci_match_id(const struct pci_device_id *ids,
> int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
> int pass);
>
> -void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> - void *userdata);
> +void __pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> + void *userdata, u32 rid, u32 mask);
> int pci_cfg_space_size(struct pci_dev *dev);
> unsigned char pci_bus_max_busnr(struct pci_bus *bus);
> void pci_setup_bridge(struct pci_bus *bus);
> resource_size_t pcibios_window_alignment(struct pci_bus *bus,
> unsigned long type);
>
> +#define pci_walk_bus(top, cb, userdata) \
> + __pci_walk_bus((top), (cb), (userdata), 0x0, 0xffff)
Please keep this close to the helper it replaces. I also really
dislike the use of this raw 0xffff. Don't we already have a named
constant that represents the mask for a RID?
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
