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

[Liviu Dudau <Liviu.Dudau@arm.com>]

On Mon, Nov 17, 2014 at 10:21:41AM +0000, 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.
> 

Please Cc: Yinghai Lu and Jiang Liu on future versions.

More comments on the conversion of pci_create_root_bus():

> 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);
> +
> +static struct resource busn_resource = {
> +       .name   = "PCI busn",
> +       .start  = 0,
> +       .end    = 255,
> +       .flags  = IORESOURCE_BUS,
> +};
> +
> +static void pci_release_host_bridge_dev(struct device *dev)
> +{
> +       struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> +
> +       if (bridge->release_fn)
> +               bridge->release_fn(bridge);
> +       pci_free_resource_list(&bridge->windows);
> +       kfree(bridge);
> +}
> +
> +struct pci_host_bridge *pci_create_host_bridge(
> +               struct device *parent, u32 db,
> +               struct pci_ops *ops, void *sysdata,

I don't thinks it is worth moving the buses' pci_ops into pci_host_bridge. It
might be more useful to have pci_host_bridge specific ops here.

> +               struct list_head *resources)
> +{
> +       int error;
> +       struct pci_bus *b;
> +       struct pci_host_bridge *host, *h;
> +       struct pci_host_bridge_window *window, *n;
> +
> +       down_read(&pci_host_bridge_sem);
> +       list_for_each_entry(h, &pci_host_bridge_list, list) {
> +               if (h->domain = PCI_DOMAIN(db) &&
> +                               h->busnum = PCI_BUSNUM(db)) {
> +                       dev_dbg(&h->dev, "pci host bridge exist\n");
> +                       up_read(&pci_host_bridge_sem);
> +                       return NULL;
> +               }
> +       }
> +       up_read(&pci_host_bridge_sem);
> +
> +       host = kzalloc(sizeof(*host), GFP_KERNEL);
> +       if (!host)
> +               return NULL;
> +
> +       host->sysdata = sysdata;
> +       host->busnum = PCI_BUSNUM(db);
> +       host->domain = PCI_DOMAIN(db);
> +       host->ops = ops;
> +       host->dev.parent = parent;
> +       INIT_LIST_HEAD(&host->windows);
> +       host->dev.release = pci_release_host_bridge_dev;
> +
> +       /* this is hack, just for build, will be removed later*/
> +       b = kzalloc(sizeof(*b), GFP_KERNEL);
> +       b->sysdata = sysdata;
> +       pci_bus_assign_domain_nr(b, parent);
> +       host->domain = pci_domain_nr(b);
> +
> +       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);
> +       }
> +
> +       dev_set_name(&host->dev, "pci%04x:%02x", host->domain,
> +                       host->busnum);
> +       error = pcibios_root_bridge_prepare(host);
> +       if(error) {
> +               kfree(host);
> +               return NULL;
> +       }
> +
> +       error = device_register(&host->dev);
> +       if (error) {
> +               put_device(&host->dev);
> +               return NULL;
> +       }
> +
> +       down_write(&pci_host_bridge_sem);
> +       list_add_tail(&host->list, &pci_host_bridge_list);
> +       up_write(&pci_host_bridge_sem);
> +       return host;
> +}
> +EXPORT_SYMBOL(pci_create_host_bridge);
> +
> +void pci_free_host_bridge(struct pci_host_bridge *host)
> +{
> +       down_write(&pci_host_bridge_sem);
> +       list_del(&host->list);
> +       up_write(&pci_host_bridge_sem);
> +
> +       device_unregister(&host->dev);
> +}
> +
>  static struct pci_bus *find_pci_root_bus(struct pci_bus *bus)
>  {
>         while (bus->parent)
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index adf4d09..d472da4 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -17,13 +17,6 @@
>  #define CARDBUS_LATENCY_TIMER  176     /* secondary latency timer */
>  #define CARDBUS_RESERVE_BUSNR  3
> 
> -static struct resource busn_resource = {
> -       .name   = "PCI busn",
> -       .start  = 0,
> -       .end    = 255,
> -       .flags  = IORESOURCE_BUS,
> -};
> -
>  /* Ugh.  Need to stop exporting this to modules. */
>  LIST_HEAD(pci_root_buses);
>  EXPORT_SYMBOL(pci_root_buses);
> @@ -508,31 +501,6 @@ static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
>         return b;
>  }
> 
> -static void pci_release_host_bridge_dev(struct device *dev)
> -{
> -       struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> -
> -       if (bridge->release_fn)
> -               bridge->release_fn(bridge);
> -
> -       pci_free_resource_list(&bridge->windows);
> -
> -       kfree(bridge);
> -}
> -
> -static struct pci_host_bridge *pci_alloc_host_bridge(struct pci_bus *b)
> -{
> -       struct pci_host_bridge *bridge;
> -
> -       bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
> -       if (!bridge)
> -               return NULL;
> -
> -       INIT_LIST_HEAD(&bridge->windows);
> -       bridge->bus = b;
> -       return bridge;
> -}
> -
>  static const unsigned char pcix_bus_speed[] = {
>         PCI_SPEED_UNKNOWN,              /* 0 */
>         PCI_SPEED_66MHz_PCIX,           /* 1 */
> @@ -1895,52 +1863,33 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
>  {
>  }
> 
> -struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
> -               struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +struct pci_bus *__pci_create_root_bus(struct pci_host_bridge *bridge)
>  {
>         int error;
> -       struct pci_host_bridge *bridge;
>         struct pci_bus *b, *b2;
> -       struct pci_host_bridge_window *window, *n;
> +       struct pci_host_bridge_window *window;
>         struct resource *res;
>         resource_size_t offset;
>         char bus_addr[64];
>         char *fmt;
> -       u8      bus = PCI_BUSNUM(db);
> +       struct device *parent = bridge->dev.parent;
> 
>         b = pci_alloc_bus(NULL);
>         if (!b)
>                 return NULL;
> 
> -       b->sysdata = sysdata;
> -       b->ops = ops;
> -       b->number = b->busn_res.start = bus;
> +       b->sysdata = bridge->sysdata;

I think bridge should be the b->sysdata here. 

> +       b->ops = bridge->ops;

See comment above why I don't think this is necessary.

> +       b->number = b->busn_res.start = bridge->busnum;
>         pci_bus_assign_domain_nr(b, parent);
> -       b2 = pci_find_bus(pci_domain_nr(b), bus);
> +       bridge->domain = pci_domain_nr(b);

Do you really want to overwrite the bridge's domain with the one from a bus that
could possibly be rejected a couple of lines further down?

As an asside: if we are doing the split of pci_host_bridge from root bus creation
it is worth in my opinion to move the domain setup in pci_create_host_bridge()
and stop fiddling with it here.

Otherwise it looks to me like you are heading in the right direction.

Best regards,
Liviu

> +       b2 = pci_find_bus(pci_domain_nr(b), bridge->busnum);
>         if (b2) {
>                 /* If we already got to this bus through a different bridge, ignore it */
>                 dev_dbg(&b2->dev, "bus already known\n");
>                 goto err_out;
>         }
> 
> -       bridge = pci_alloc_host_bridge(b);
> -       if (!bridge)
> -               goto err_out;
> -
> -       bridge->dev.parent = parent;
> -       bridge->dev.release = pci_release_host_bridge_dev;
> -       dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
> -       error = pcibios_root_bridge_prepare(bridge);
> -       if (error) {
> -               kfree(bridge);
> -               goto err_out;
> -       }
> -
> -       error = device_register(&bridge->dev);
> -       if (error) {
> -               put_device(&bridge->dev);
> -               goto err_out;
> -       }
>         b->bridge = get_device(&bridge->dev);
>         device_enable_async_suspend(b->bridge);
>         pci_set_bus_of_node(b);
> @@ -1950,7 +1899,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
> 
>         b->dev.class = &pcibus_class;
>         b->dev.parent = b->bridge;
> -       dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
> +       dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), b->number);
>         error = device_register(&b->dev);
>         if (error)
>                 goto class_dev_reg_err;
> @@ -1966,12 +1915,11 @@ struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>                 printk(KERN_INFO "PCI host bridge to bus %s\n", dev_name(&b->dev));
> 
>         /* Add initial resources to the bus */
> -       list_for_each_entry_safe(window, n, resources, list) {
> -               list_move_tail(&window->list, &bridge->windows);
> +       list_for_each_entry(window, &bridge->windows, list) {
>                 res = window->res;
>                 offset = window->offset;
>                 if (res->flags & IORESOURCE_BUS)
> -                       pci_bus_insert_busn_res(b, bus, res->end);
> +                       pci_bus_insert_busn_res(b, b->number, res->end);
>                 else
>                         pci_bus_add_resource(b, res, 0);
>                 if (offset) {
> @@ -2001,6 +1949,25 @@ err_out:
>         return NULL;
>  }
> 
> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 bus,
> +               struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +{
> +       struct pci_host_bridge *host;
> +
> +       host = pci_create_host_bridge(parent, bus, ops,
> +                       sysdata ,resources);
> +       if (!host)
> +               return NULL;
> +
> +       host->bus = __pci_create_root_bus(host);
> +       if (!host->bus) {
> +               pci_free_host_bridge(host);
> +               return NULL;
> +       }
> +
> +       return host->bus;
> +}
> +
>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
>  {
>         struct resource *res = &b->busn_res;
> @@ -2069,40 +2036,37 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
>  {
>         struct pci_host_bridge_window *window;
>         bool found = false;
> -       struct pci_bus *b;
> -       LIST_HEAD(default_res);
> +       struct pci_host_bridge *host;
>         int max;
> 
> -       if (!resources) {
> -               pci_add_resource(&default_res, &ioport_resource);
> -               pci_add_resource(&default_res, &iomem_resource);
> -               pci_add_resource(&default_res, &busn_resource);
> -       } else {
> -               list_for_each_entry(window, resources, list)
> -                       if (window->res->flags & IORESOURCE_BUS) {
> -                               found = true;
> -                               break;
> -                       }
> -       }
> +       host = pci_create_host_bridge(parent, db, ops, sysdata, resources);
> +       if (!host)
> +               return NULL;
> 
> -       b = pci_create_root_bus(parent, db, ops, sysdata,
> -                       resources ? resources : &default_res);
> -       if (!b)
> +       list_for_each_entry(window, &host->windows, list)
> +               if (window->res->flags & IORESOURCE_BUS) {
> +                       found = true;
> +                       break;
> +               }
> +
> +       host->bus = __pci_create_root_bus(host);
> +       if (!host->bus) {
> +               pci_free_host_bridge(host);
>                 return NULL;
> +       }
> 
>         if (!found) {
> -               dev_info(&b->dev,
> +               dev_info(&host->bus->dev,
>                  "No busn resource found for root bus, will use [bus %02x-ff]\n",
>                         PCI_BUSNUM(db));
> -               pci_bus_insert_busn_res(b, PCI_BUSNUM(db), 255);
> +               pci_bus_insert_busn_res(host->bus, PCI_BUSNUM(db), 255);
>         }
> 
> -       max = pci_scan_child_bus(b);
> -
> +       max = pci_scan_child_bus(host->bus);
>         if (!found)
> -               pci_bus_update_busn_res_end(b, max);
> +               pci_bus_update_busn_res_end(host->bus, max);
> 
> -       return b;
> +       return host->bus;
>  }
>  EXPORT_SYMBOL(pci_scan_root_bus);
> 
> 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;
> +       int domain;
> +       void *sysdata;
> +       struct pci_ops *ops;
>         void (*release_fn)(struct pci_host_bridge *);
>         void *release_data;
>  };
> @@ -413,7 +418,9 @@ void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
>                      void *release_data);
> 
>  int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge);
> -
> +struct pci_host_bridge *pci_create_host_bridge(
> +               struct device *parent, u32 db, struct pci_ops *ops,
> +               void *sys, struct list_head *resources);
>  /*
>   * The first PCI_BRIDGE_RESOURCE_NUM PCI bus resources (those that correspond
>   * to P2P or CardBus bridge windows) go in a table.  Additional ones (for
> @@ -770,6 +777,8 @@ void pci_bus_add_devices(const struct pci_bus *bus);
>  struct pci_bus *pci_create_root_bus(struct device *parent, u32 bus,
>                                     struct pci_ops *ops, void *sysdata,
>                                     struct list_head *resources);
> +struct pci_bus *__pci_create_root_bus(struct pci_host_bridge *host);
> +void pci_free_host_bridge(struct pci_host_bridge *host);
>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
>  int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
>  void pci_bus_release_busn_res(struct pci_bus *b);
> --
> 1.7.1
> 
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