Re: [PATCH 01/15] PCI, acpiphp: Separate out hot-add support of pci host bridge

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On Thu, Dec 6, 2012 at 11:25 PM, Myron Stowe <myron.stowe@xxxxxxxxxx> wrote:
> From: Yinghai Lu <yinghai@xxxxxxxxxx>
>
> It causes confusion.

I completely agree that acpiphp causes confusion  :)

> We may only need acpi hp for pci host bridge.
>
> Split host bridge hot-add support to pci_root_hp, and keep acpiphp simple.
>
> -v2: put back pci_root_hp change in one patch
> -v3: add pcibios_resource_survey_bus() calling
> -v4: remove not needed code with remove_bridge
> -v5: put back support for acpiphp support for slots just on root bus.
> -v6: change some functions to *_p2p_* to make it more clean.
> -v7: split hot_added change out.
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> Signed-off-by: Myron Stowe <myron.stowe@xxxxxxxxxx>
> ---
>
>  drivers/acpi/Makefile              |    1
>  drivers/acpi/pci_root_hp.c         |  228 ++++++++++++++++++++++++++++++++++++
>  drivers/pci/hotplug/acpiphp_glue.c |   59 ++-------
>  3 files changed, 244 insertions(+), 44 deletions(-)
>  create mode 100644 drivers/acpi/pci_root_hp.c
>
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 82422fe..4edfe41 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -36,6 +36,7 @@ acpi-y                                += processor_core.o
>  acpi-y                         += ec.o
>  acpi-$(CONFIG_ACPI_DOCK)       += dock.o
>  acpi-y                         += pci_root.o pci_link.o pci_irq.o pci_bind.o
> +acpi-$(CONFIG_HOTPLUG)         += pci_root_hp.o

I absolutely, 110% agree with splitting out the host bridge hotplug
code from the PCI device hotplug code.

But I don't want to put this in a separate file; I think it should go
directly in pci_root.c.  Putting it in a separate file gives the
illusion that hotplug is something we only do in unusual
circumstances.  But that's wrong -- even at boot-time we should be
using the same hot-plug flow as we do later.

Plus, I want people to be forced to look at the ugliness of this code
every time they look at pci_root.c.  Maybe that will help get it
cleaned up eventually.

For example, as soon as you put this code in pci_root.c instead of
pci_root_hp.c, it becomes obvious that we're keeping a list of host
bridges in both places, and we probably don't need two lists.  And it
seems dubious that acpi_pci_root_hp_init() is an initcall that walks
the namespace looking for host bridges, when acpi_pci_root_add()
already exists and is called for every host bridge.

Bjorn

>  acpi-y                         += power.o
>  acpi-y                         += event.o
>  acpi-y                         += sysfs.o
> diff --git a/drivers/acpi/pci_root_hp.c b/drivers/acpi/pci_root_hp.c
> new file mode 100644
> index 0000000..10c12aa
> --- /dev/null
> +++ b/drivers/acpi/pci_root_hp.c
> @@ -0,0 +1,228 @@
> +/*
> + * Separated from drivers/pci/hotplug/acpiphp_glue.c
> + *     only support root bridge
> + */
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +
> +#include <linux/kernel.h>
> +#include <linux/pci.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/acpi.h>
> +
> +static LIST_HEAD(acpi_root_bridge_list);
> +struct acpi_root_bridge {
> +       struct list_head list;
> +       acpi_handle handle;
> +       u32 flags;
> +};
> +
> +/* bridge flags */
> +#define ROOT_BRIDGE_HAS_EJ0    (0x00000002)
> +#define ROOT_BRIDGE_HAS_PS3    (0x00000080)
> +
> +#define ACPI_STA_FUNCTIONING   (0x00000008)
> +
> +static struct acpi_root_bridge *acpi_root_handle_to_bridge(acpi_handle handle)
> +{
> +       struct acpi_root_bridge *bridge;
> +
> +       list_for_each_entry(bridge, &acpi_root_bridge_list, list)
> +               if (bridge->handle == handle)
> +                       return bridge;
> +
> +       return NULL;
> +}
> +
> +/* allocate and initialize host bridge data structure */
> +static void add_acpi_root_bridge(acpi_handle handle)
> +{
> +       struct acpi_root_bridge *bridge;
> +       acpi_handle dummy_handle;
> +       acpi_status status;
> +
> +       /* if the bridge doesn't have _STA, we assume it is always there */
> +       status = acpi_get_handle(handle, "_STA", &dummy_handle);
> +       if (ACPI_SUCCESS(status)) {
> +               unsigned long long tmp;
> +
> +               status = acpi_evaluate_integer(handle, "_STA", NULL, &tmp);
> +               if (ACPI_FAILURE(status)) {
> +                       printk(KERN_DEBUG "%s: _STA evaluation failure\n",
> +                                                __func__);
> +                       return;
> +               }
> +               if ((tmp & ACPI_STA_FUNCTIONING) == 0)
> +                       /* don't register this object */
> +                       return;
> +       }
> +
> +       bridge = kzalloc(sizeof(struct acpi_root_bridge), GFP_KERNEL);
> +       if (!bridge)
> +               return;
> +
> +       bridge->handle = handle;
> +
> +       if (ACPI_SUCCESS(acpi_get_handle(handle, "_EJ0", &dummy_handle)))
> +               bridge->flags |= ROOT_BRIDGE_HAS_EJ0;
> +       if (ACPI_SUCCESS(acpi_get_handle(handle, "_PS3", &dummy_handle)))
> +               bridge->flags |= ROOT_BRIDGE_HAS_PS3;
> +
> +       list_add(&bridge->list, &acpi_root_bridge_list);
> +}
> +
> +struct acpi_root_hp_work {
> +       struct work_struct work;
> +       acpi_handle handle;
> +       u32 type;
> +       void *context;
> +};
> +
> +static void alloc_acpi_root_hp_work(acpi_handle handle, u32 type,
> +                                       void *context,
> +                                       void (*func)(struct work_struct *work))
> +{
> +       struct acpi_root_hp_work *hp_work;
> +       int ret;
> +
> +       hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
> +       if (!hp_work)
> +               return;
> +
> +       hp_work->handle = handle;
> +       hp_work->type = type;
> +       hp_work->context = context;
> +
> +       INIT_WORK(&hp_work->work, func);
> +       ret = queue_work(kacpi_hotplug_wq, &hp_work->work);
> +       if (!ret)
> +               kfree(hp_work);
> +}
> +
> +static void handle_root_bridge_insertion(acpi_handle handle)
> +{
> +       struct acpi_device *device, *pdevice;
> +       acpi_handle phandle;
> +       int ret_val;
> +
> +       acpi_get_parent(handle, &phandle);
> +       if (acpi_bus_get_device(phandle, &pdevice)) {
> +               printk(KERN_DEBUG "no parent device, assuming NULL\n");
> +               pdevice = NULL;
> +       }
> +       if (!acpi_bus_get_device(handle, &device)) {
> +               /* check if  pci root_bus is removed */
> +               struct acpi_pci_root *root = acpi_driver_data(device);
> +               if (pci_find_bus(root->segment, root->secondary.start))
> +                       return;
> +
> +               printk(KERN_DEBUG "bus exists... trim\n");
> +               /* this shouldn't be in here, so remove
> +                * the bus then re-add it...
> +                */
> +               ret_val = acpi_bus_trim(device, 1);
> +               printk(KERN_DEBUG "acpi_bus_trim return %x\n", ret_val);
> +       }
> +       if (acpi_bus_add(&device, pdevice, handle, ACPI_BUS_TYPE_DEVICE)) {
> +               printk(KERN_ERR "cannot add bridge to acpi list\n");
> +               return;
> +       }
> +       if (acpi_bus_start(device))
> +               printk(KERN_ERR "cannot start bridge\n");
> +}
> +
> +static void _handle_hotplug_event_root(struct work_struct *work)
> +{
> +       struct acpi_root_bridge *bridge;
> +       char objname[64];
> +       struct acpi_buffer buffer = { .length = sizeof(objname),
> +                                     .pointer = objname };
> +       struct acpi_root_hp_work *hp_work;
> +       acpi_handle handle;
> +       u32 type;
> +
> +       hp_work = container_of(work, struct acpi_root_hp_work, work);
> +       handle = hp_work->handle;
> +       type = hp_work->type;
> +
> +       bridge = acpi_root_handle_to_bridge(handle);
> +
> +       acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> +
> +       switch (type) {
> +       case ACPI_NOTIFY_BUS_CHECK:
> +               /* bus enumerate */
> +               printk(KERN_DEBUG "%s: Bus check notify on %s\n", __func__,
> +                                objname);
> +               if (!bridge) {
> +                       handle_root_bridge_insertion(handle);
> +                       add_acpi_root_bridge(handle);
> +               }
> +
> +               break;
> +
> +       case ACPI_NOTIFY_DEVICE_CHECK:
> +               /* device check */
> +               printk(KERN_DEBUG "%s: Device check notify on %s\n", __func__,
> +                                objname);
> +               if (!bridge) {
> +                       handle_root_bridge_insertion(handle);
> +                       add_acpi_root_bridge(handle);
> +               }
> +               break;
> +
> +       default:
> +               printk(KERN_WARNING "notify_handler: unknown event type 0x%x for %s\n",
> +                                type, objname);
> +               break;
> +       }
> +
> +       kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
> +}
> +
> +static void handle_hotplug_event_root(acpi_handle handle, u32 type,
> +                                       void *context)
> +{
> +       alloc_acpi_root_hp_work(handle, type, context,
> +                               _handle_hotplug_event_root);
> +}
> +
> +static acpi_status __init
> +find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
> +{
> +       char objname[64];
> +       struct acpi_buffer buffer = { .length = sizeof(objname),
> +                                     .pointer = objname };
> +       int *count = (int *)context;
> +
> +       if (!acpi_is_root_bridge(handle))
> +               return AE_OK;
> +
> +       (*count)++;
> +
> +       acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> +
> +       acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> +                               handle_hotplug_event_root, NULL);
> +       printk(KERN_DEBUG "acpi root: %s notify handler installed\n", objname);
> +
> +       add_acpi_root_bridge(handle);
> +
> +       return AE_OK;
> +}
> +
> +static int __init acpi_pci_root_hp_init(void)
> +{
> +       int num = 0;
> +
> +       acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> +               ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
> +
> +       printk(KERN_DEBUG "Found %d acpi root devices\n", num);
> +
> +       return 0;
> +}
> +
> +subsys_initcall(acpi_pci_root_hp_init);
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index 3d6d4fd..d0369dc 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -543,10 +543,13 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
>         acpi_status status;
>         acpi_handle handle = bridge->handle;
>
> -       status = acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> +       if (bridge->type != BRIDGE_TYPE_HOST) {
> +               status = acpi_remove_notify_handler(handle,
> +                                           ACPI_SYSTEM_NOTIFY,
>                                             handle_hotplug_event_bridge);
> -       if (ACPI_FAILURE(status))
> -               err("failed to remove notify handler\n");
> +               if (ACPI_FAILURE(status))
> +                       err("failed to remove notify handler\n");
> +       }
>
>         if ((bridge->type != BRIDGE_TYPE_HOST) &&
>             ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func)) {
> @@ -630,9 +633,6 @@ static void remove_bridge(struct acpi_pci_root *root)
>         bridge = acpiphp_handle_to_bridge(handle);
>         if (bridge)
>                 cleanup_bridge(bridge);
> -       else
> -               acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> -                                          handle_hotplug_event_bridge);
>  }
>
>  static int power_on_slot(struct acpiphp_slot *slot)
> @@ -1107,18 +1107,12 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus)
>  }
>
>  /* Program resources in newly inserted bridge */
> -static int acpiphp_configure_bridge (acpi_handle handle)
> +static int acpiphp_configure_p2p_bridge(acpi_handle handle)
>  {
> -       struct pci_bus *bus;
> +       struct pci_dev *pdev = acpi_get_pci_dev(handle);
> +       struct pci_bus *bus = pdev->subordinate;
>
> -       if (acpi_is_root_bridge(handle)) {
> -               struct acpi_pci_root *root = acpi_pci_find_root(handle);
> -               bus = root->bus;
> -       } else {
> -               struct pci_dev *pdev = acpi_get_pci_dev(handle);
> -               bus = pdev->subordinate;
> -               pci_dev_put(pdev);
> -       }
> +       pci_dev_put(pdev);
>
>         pci_bus_size_bridges(bus);
>         pci_bus_assign_resources(bus);
> @@ -1128,7 +1122,7 @@ static int acpiphp_configure_bridge (acpi_handle handle)
>         return 0;
>  }
>
> -static void handle_bridge_insertion(acpi_handle handle, u32 type)
> +static void handle_p2p_bridge_insertion(acpi_handle handle, u32 type)
>  {
>         struct acpi_device *device, *pdevice;
>         acpi_handle phandle;
> @@ -1148,9 +1142,9 @@ static void handle_bridge_insertion(acpi_handle handle, u32 type)
>                 err("cannot add bridge to acpi list\n");
>                 return;
>         }
> -       if (!acpiphp_configure_bridge(handle) &&
> +       if (!acpiphp_configure_p2p_bridge(handle) &&
>                 !acpi_bus_start(device))
> -               add_bridge(handle);
> +               add_p2p_bridge(handle);
>         else
>                 err("cannot configure and start bridge\n");
>
> @@ -1236,7 +1230,7 @@ static void _handle_hotplug_event_bridge(struct work_struct *work)
>
>         if (acpi_bus_get_device(handle, &device)) {
>                 /* This bridge must have just been physically inserted */
> -               handle_bridge_insertion(handle, type);
> +               handle_p2p_bridge_insertion(handle, type);
>                 goto out;
>         }
>
> @@ -1413,21 +1407,6 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type,
>                               _handle_hotplug_event_func);
>  }
>
> -static acpi_status
> -find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
> -{
> -       int *count = (int *)context;
> -
> -       if (!acpi_is_root_bridge(handle))
> -               return AE_OK;
> -
> -       (*count)++;
> -       acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> -                                   handle_hotplug_event_bridge, NULL);
> -
> -       return AE_OK ;
> -}
> -
>  static struct acpi_pci_driver acpi_pci_hp_driver = {
>         .add =          add_bridge,
>         .remove =       remove_bridge,
> @@ -1438,15 +1417,7 @@ static struct acpi_pci_driver acpi_pci_hp_driver = {
>   */
>  int __init acpiphp_glue_init(void)
>  {
> -       int num = 0;
> -
> -       acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> -                       ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
> -
> -       if (num <= 0)
> -               return -1;
> -       else
> -               acpi_pci_register_driver(&acpi_pci_hp_driver);
> +       acpi_pci_register_driver(&acpi_pci_hp_driver);
>
>         return 0;
>  }
>
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