Re: [RFC PATCH 07/16] PCI: Separate pci_host_bridge creation out of pci_create_root_bus()

Arnd Bergmann
2014-11-17T10:57:56Z

On Monday 17 November 2014 18:21:41 Yijing Wang wrote:
> There are some common PCI infos like domain, msi_controller, these
> infos are saved in arch PCI sysdata, and lots arch specific functions
> like pci_domain_nr() and pcibios_msi_controller() required.
> We could separate pci_host_bridge creation out of pci_create_root_bus(),
> then we could put the common infos in, then we could eliminate
> the arch specifc functions.
>
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
> drivers/pci/host-bridge.c | 99 +++++++++++++++++++++++++++++++++
> drivers/pci/probe.c | 134 ++++++++++++++++----------------------------
> include/linux/pci.h | 11 +++-
> 3 files changed, 158 insertions(+), 86 deletions(-)
>
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index 0e5f3c9..e31604f 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -8,6 +8,105 @@
>
> #include "pci.h"
>
> +LIST_HEAD(pci_host_bridge_list);
> +DECLARE_RWSEM(pci_host_bridge_sem);

Unless the pci_host_bridge_sem is accessed thousands of times per second,
it's normally better to use a simple mutex instead.

> +static struct resource busn_resource = {
> + .name = "PCI busn",
> + .start = 0,
> + .end = 255,
> + .flags = IORESOURCE_BUS,
> +};

I think it would be better to require callers to pass the bus resource
down to the function.

> +struct pci_host_bridge *pci_create_host_bridge(
> + struct device *parent, u32 db,
> + struct pci_ops *ops, void *sysdata,
> + struct list_head *resources)
> +{

Do we still need to pass the 'sysdata' in here? If we are guaranteed to
have a device pointer, we should always be able to get the driver
private data from dev_get_drvdata(host->dev->parent).

> + host = kzalloc(sizeof(*host), GFP_KERNEL);
> + if (!host)
> + return NULL;

devm_kzalloc maybe?

> + if (!resources) {
> + /* Use default IO/MEM/BUS resources*/
> + pci_add_resource(&host->windows, &ioport_resource);
> + pci_add_resource(&host->windows, &iomem_resource);
> + pci_add_resource(&host->windows, &busn_resource);
> + } else {
> + list_for_each_entry_safe(window, n, resources, list)
> + list_move_tail(&window->list, &host->windows);
> + }

I think we should assume that the correct resources are passed. You
could add a wrapper around this function to convert old platforms
though.

> +EXPORT_SYMBOL(pci_create_host_bridge);

EXPORT_SYMBOL_GPL() maybe?

> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 8b11b38..daa7f40 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -402,7 +402,12 @@ struct pci_host_bridge_window {
> struct pci_host_bridge {
> struct device dev;
> struct pci_bus *bus; /* root bus */
> + struct list_head list;
> struct list_head windows; /* pci_host_bridge_windows */
> + int busnum;

The busnum should already be implied through the bus resource.

Arnd