Re: [RFC PATCH 08/16] PCI: Introduce pci_scan_host_bridge() and pci_host_info

Liviu Dudau
2014-11-18T15:42:43Z

On Mon, Nov 17, 2014 at 10:21:42AM +0000, Yijing Wang wrote:
> From: Yijing Wang <wangyijing0307@gmail.com>
>
> Now pci_host_bridge has been ripped out from pci root
> bus creation. Currently pci_scan_root_bus() lacks
> scalability, so platform host drivers have no proper
> way to configure pci_host_bridge. E.g we should assign
> msi_controller to pci_host_bridge, add argument for
> pci_scan_root_bus() is not a good idea, it has already
> five, so introudce struct pci_host_info to make
> pci scan interfaces more scalable. Because almost
> all host drivers need to configure host resources,
> so we put .init_res() in it first, and add other
> hooks when need.
>
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
> drivers/pci/host-bridge.c | 27 +++++++++-------
> drivers/pci/probe.c | 73 ++++++++++++++++++++++++++++++++++++++++++--
> include/linux/pci.h | 20 ++++++++++++-
> 3 files changed, 103 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index e31604f..49b6c21 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -8,9 +8,6 @@
>
> #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,
> @@ -18,6 +15,9 @@ static struct resource busn_resource = {
> .flags = IORESOURCE_BUS,
> };
>
> +LIST_HEAD(pci_host_bridge_list);
> +DECLARE_RWSEM(pci_host_bridge_sem);
> +
> static void pci_release_host_bridge_dev(struct device *dev)
> {
> struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> @@ -29,14 +29,12 @@ static void pci_release_host_bridge_dev(struct device *dev)
> }
>
> struct pci_host_bridge *pci_create_host_bridge(
> - struct device *parent, u32 db,
> - struct pci_ops *ops, void *sysdata,
> - struct list_head *resources)
> + struct device *parent, u32 db, struct pci_ops *ops,
> + struct pci_host_info *info)
> {
> 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) {
> @@ -53,7 +51,7 @@ struct pci_host_bridge *pci_create_host_bridge(
> if (!host)
> return NULL;
>
> - host->sysdata = sysdata;
> + host->sysdata = info->arg;
> host->busnum = PCI_BUSNUM(db);
> host->domain = PCI_DOMAIN(db);
> host->ops = ops;
> @@ -63,18 +61,23 @@ struct pci_host_bridge *pci_create_host_bridge(
>
> /* this is hack, just for build, will be removed later*/

Why do you need this hack? Just for calling pci_domain_nr() ?

> b = kzalloc(sizeof(*b), GFP_KERNEL);
> - b->sysdata = sysdata;
> + b->sysdata = host->sysdata;
> pci_bus_assign_domain_nr(b, parent);
> host->domain = pci_domain_nr(b);
> + kfree(b);
>
> - if (!resources) {
> + if (info->res_type = PCI_HOST_RES_DEFAULT) {
> /* 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);
> + if (!info->init_res || info->init_res(host, info)) {
> + pr_err("pci host %04x:%02x init resources fail\n",
> + host->domain, host->busnum);
> + kfree(host);
> + return NULL;
> + }
> }
>
> dev_set_name(&host->dev, "pci%04x:%02x", host->domain,
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index d472da4..42158fd 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1863,6 +1863,21 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
> {
> }
>
> +static int pci_default_init_res(struct pci_host_bridge *host,
> + struct pci_host_info *info)
> +{
> + struct pci_host_bridge_window *window, *n;
> +
> + if (info->res_type != PCI_HOST_RES_DEFAULT)
> + list_for_each_entry_safe(window, n, info->resources,
> + list)
> + list_move_tail(&window->list, &host->windows);
> + else
> + info->res_type = PCI_HOST_RES_DEFAULT;

I'm confused about this assignment. Isn't this a nop as the else part
means info->res_type *is* PCI_HOST_RES_DEFAULT?

> +
> + return 0;
> +}
> +
> struct pci_bus *__pci_create_root_bus(struct pci_host_bridge *bridge)
> {
> int error;
> @@ -1949,13 +1964,17 @@ err_out:
> return NULL;
> }
>
> -struct pci_bus *pci_create_root_bus(struct device *parent, u32 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_host_bridge *host;
> + struct pci_host_info info;
> +
> + info.arg= sysdata;
> + info.resources = resources;
> + info.init_res = pci_default_init_res;
>
> - host = pci_create_host_bridge(parent, bus, ops,
> - sysdata ,resources);
> + host = pci_create_host_bridge(parent, db, ops, &info);
> if (!host)
> return NULL;
>
> @@ -2038,8 +2057,13 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
> bool found = false;
> struct pci_host_bridge *host;
> int max;
> + struct pci_host_info info;
> +
> + info.arg = sysdata;
> + info.resources = resources;
> + info.init_res = pci_default_init_res;

I have mixed feelings about this patch. While it is heading in the right direction
of moving pci_host_bridge relevant information towards the right user, I don't think
you picked up the right set to move. The resource list is going to be copied into
internal pci_host_bridge list anyway, keeping another copy is not helpful *and*
you have increased the code size.

I think for now we should aim to get the *missing* data into pci_host_bridge: MSI
controllers and PCI domain/segment. Then we can do more cleanup.

>
> - host = pci_create_host_bridge(parent, db, ops, sysdata, resources);
> + host = pci_create_host_bridge(parent, db, ops, &info);
> if (!host)
> return NULL;
>
> @@ -2070,6 +2094,47 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
> }
> EXPORT_SYMBOL(pci_scan_root_bus);
>
> +struct pci_host_bridge *pci_scan_host_bridge(
> + struct device *parent, u32 db, struct pci_ops *ops,
> + struct pci_host_info *info)
> +{
> + struct pci_host_bridge_window *window;
> + bool found = false;
> + struct pci_host_bridge *host;
> + int max;
> +
> + host = pci_create_host_bridge(parent, db, ops, info);
> + if (!host)
> + return NULL;
> +
> + 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(&host->bus->dev,
> + "No busn resource found for root bus, will use [bus %02x-ff]\n",
> + host->busnum);
> + pci_bus_insert_busn_res(host->bus, host->busnum, 255);
> + }
> +
> + max = pci_scan_child_bus(host->bus);
> + if (!found)
> + pci_bus_update_busn_res_end(host->bus, max);
> +
> + return host;
> +
> +}
> +EXPORT_SYMBOL(pci_scan_host_bridge);
> +
> /**
> * pci_rescan_bus_bridge_resize - scan a PCI bus for devices.
> * @bridge: PCI bridge for the bus to scan
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index daa7f40..a51f5f5 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -412,6 +412,21 @@ struct pci_host_bridge {
> void *release_data;
> };
>
> +struct pci_host_info {
> + u8 res_type;
> + void *arg;
> + struct list_head *resources; /*just for build, will clean up later */
> + int (*init_res)(struct pci_host_bridge *host,
> + struct pci_host_info *info);
> +};
> +
> +static inline void init_pci_host_info(struct pci_host_info *info)
> +{
> + memset(info, 0 , sizeof(*info));
> +}

Where is this used?

> +
> +#define PCI_HOST_RES_DEFAULT 0x2
> +

Magic number?

Best regards,
Liviu

> #define to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev)
> void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
> void (*release_fn)(struct pci_host_bridge *),
> @@ -420,7 +435,7 @@ void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
> 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);
> + struct pci_host_info *info);
> /*
> * 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
> @@ -785,6 +800,9 @@ void pci_bus_release_busn_res(struct pci_bus *b);
> struct pci_bus *pci_scan_root_bus(struct device *parent, u32 bus,
> struct pci_ops *ops, void *sysdata,
> struct list_head *resources);
> +struct pci_host_bridge *pci_scan_host_bridge(struct device *parent,
> + u32 db, struct pci_ops *ops,
> + struct pci_host_info *info);
> struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
> int busnr);
> void pcie_update_link_speed(struct pci_bus *bus, u16 link_status);
> --
> 1.7.1
>
> --
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