[U-Boot] [PATCH 05/15] dm: pci: Add a way to iterate through all PCI devices

[Bin Meng]

Hi Simon,

On Tue, Jul 28, 2015 at 5:47 AM, Simon Glass <sjg at chromium.org> wrote:
> These functions allow iteration through all PCI devices including bridges.
> The children of each PCI bus are returned in turn. This can be useful for
> configuring, checking or enumerating all the devices.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  drivers/pci/pci-uclass.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/pci.h            | 25 +++++++++++++++++++++
>  2 files changed, 83 insertions(+)
>
> diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
> index 8d3536c..da724ca 100644
> --- a/drivers/pci/pci-uclass.c
> +++ b/drivers/pci/pci-uclass.c
> @@ -779,6 +779,64 @@ static int pci_bridge_write_config(struct udevice *bus, pci_dev_t bdf,
>         return pci_bus_write_config(hose->ctlr, bdf, offset, value, size);
>  }
>
> +static int skip_to_next_device(struct udevice *bus, struct udevice **devp)
> +{
> +       struct udevice *dev;
> +       int ret = 0;
> +
> +       do {
> +               do {
> +                       device_find_first_child(bus, &dev);
> +                       if (dev) {
> +                               *devp = dev;
> +                               return 0;
> +                       }
> +               } while (dev);

There is no need to do a 'do..while' here.

> +               ret = uclass_next_device(&bus);

I don't understand. If there is no child device of the root pci bus,
why do we bother doing this uclass_next_device()? No child device of
the root pci bus means there will not be another bus device which is
attached to the root pci bus.

> +               if (ret)
> +                       return ret;
> +       } while (bus);
> +
> +       return 0;
> +}
> +
> +int pci_find_next_device(struct udevice **devp)
> +{
> +       struct udevice *child = *devp;
> +       struct udevice *bus = child->parent;
> +       int ret;
> +
> +       /* First try all the siblings */
> +       *devp = NULL;
> +       while (child) {
> +               device_find_next_child(&child);
> +               if (child) {
> +                       *devp = child;
> +                       return 0;
> +               }
> +       }
> +
> +       /* We ran out of siblings. Try the next bus */
> +       ret = uclass_next_device(&bus);
> +       if (ret)
> +               return ret;
> +
> +       return bus ? skip_to_next_device(bus, devp) : 0;
> +}
> +
> +int pci_find_first_device(struct udevice **devp)
> +{
> +       struct udevice *bus;
> +       int ret;
> +
> +       *devp = NULL;
> +       ret = uclass_first_device(UCLASS_PCI, &bus);
> +       if (ret)
> +               return ret;
> +
> +       return skip_to_next_device(bus, devp);
> +}
> +
>  UCLASS_DRIVER(pci) = {
>         .id             = UCLASS_PCI,
>         .name           = "pci",
> diff --git a/include/pci.h b/include/pci.h
> index 0bb3090..c842f78 100644
> --- a/include/pci.h
> +++ b/include/pci.h
> @@ -869,6 +869,31 @@ int pci_bus_find_devfn(struct udevice *bus, pci_dev_t find_devfn,
>                        struct udevice **devp);
>
>  /**
> + * pci_find_first_device() - return the first available PCI device
> + *
> + * This function and pci_find_first_device() allow iteration through all
> + * available PCI devices on all buses. Assuming there are any, this will
> + * return the first one.
> + *
> + * @devp:      Set to the first available device, or NULL if no more are left
> + *             or we got an error
> + * @return 0 if all is OK, -ve on error (e.g. a bus/bridge failed to probe)
> + */
> +int pci_find_first_device(struct udevice **devp);
> +
> +/**
> + * pci_find_next_device() - return the next available PCI device
> + *
> + * Finds the next available PCI device after the one supplied, or sets @devp
> + * to NULL if there are no more.
> + *
> + * @devp:      On entry, the last device returned. Set to the next available
> + *             device, or NULL if no more are left or we got an error
> + * @return 0 if all is OK, -ve on error (e.g. a bus/bridge failed to probe)
> + */
> +int pci_find_next_device(struct udevice **devp);
> +
> +/**
>   * pci_get_ff() - Returns a mask for the given access size
>   *
>   * @size:      Access size
> --

Regards,
Bin