diff mbox

[RFC,4/4] arm64, acpi, pci: Provide arch-specific calls for PCI host bridge dirver (PNP0A03).

Message ID 1415366876-30811-5-git-send-email-tomasz.nowicki@linaro.org
State New
Headers show

Commit Message

Tomasz Nowicki Nov. 7, 2014, 1:27 p.m. UTC
Code inspired by arch/x86/pci/acpi.c and arch/ia64/pci/pci.c files.
The main reasons why we need this:
- parse and manage resources (BUS, IO and MEM)
- create pci root bus and enumerate its children
- provide PCI config space accessors (via MMCONFIG)

Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
---
 arch/arm64/include/asm/pci.h |   8 +
 arch/arm64/kernel/pci.c      | 401 +++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 391 insertions(+), 18 deletions(-)

Comments

Arnd Bergmann Nov. 7, 2014, 2:24 p.m. UTC | #1
On Friday 07 November 2014 14:27:56 Tomasz Nowicki wrote:
>  
>  #ifdef CONFIG_PCI
> +struct pci_controller {
> +	struct acpi_device *companion;
> +	int segment;
> +	int node;		/* nearest node with memory or NUMA_NO_NODE for global allocation */
> +};
> +
> +#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
> +

Don't use busdev->sysdata in architecture specific code, it belongs to the
host bridge driver with the new model. For ACPI you don't have a host bridge
driver, but it's better to keep these separate.

The segment is always the same as the domain number, so just use that.
The node and companion members here can get added to struct pci_host_bridge.

> @@ -43,7 +53,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>   */
>  int pcibios_add_device(struct pci_dev *dev)
>  {
> -	dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
> +	if (acpi_disabled)
> +		dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
>  
>  	return 0;
>  }

How do you assign the irq number with ACPI? Do you only support MSI?

>  /*
>   * raw_pci_read/write - Platform-specific PCI config space access.
> - *
> - * Default empty implementation.  Replace with an architecture-specific setup
> - * routine, if necessary.
>   */
>  int raw_pci_read(unsigned int domain, unsigned int bus,
>  		  unsigned int devfn, int reg, int len, u32 *val)
>  {
> -	return -EINVAL;
> +	char __iomem *addr;
> +
> +	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
> +err:		*val = -1;
> +		return -EINVAL;
> +	}
> +
> +	rcu_read_lock();
> +	addr = pci_dev_base(domain, bus, devfn);
> +	if (!addr) {
> +		rcu_read_unlock();
> +		goto err;
> +	}

The config space accessors should probably be shared with
drivers/pci/host/pci-host-generic.c, e.g. by moving the rest of
the new code in there as well, or by moving the config space
accessors from that file to drivers/pci/mmconfig.c.

	Arnd
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Liviu Dudau Nov. 7, 2014, 2:55 p.m. UTC | #2
On Fri, Nov 07, 2014 at 01:27:56PM +0000, Tomasz Nowicki wrote:
> Code inspired by arch/x86/pci/acpi.c and arch/ia64/pci/pci.c files.
> The main reasons why we need this:
> - parse and manage resources (BUS, IO and MEM)
> - create pci root bus and enumerate its children
> - provide PCI config space accessors (via MMCONFIG)

Hi Tomasz,

I have some comments to your code:

> 
> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
> ---
>  arch/arm64/include/asm/pci.h |   8 +
>  arch/arm64/kernel/pci.c      | 401 +++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 391 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
> index fded096..ecd940f 100644
> --- a/arch/arm64/include/asm/pci.h
> +++ b/arch/arm64/include/asm/pci.h
> @@ -33,6 +33,14 @@ static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
>  extern int isa_dma_bridge_buggy;
> 
>  #ifdef CONFIG_PCI
> +struct pci_controller {
> +       struct acpi_device *companion;
> +       int segment;
> +       int node;               /* nearest node with memory or NUMA_NO_NODE for global allocation */
> +};
> +
> +#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)

I am trying to move away from the model where the architecture dictates the shape
of the pci_controller structure. Can I suggest that you put all this code and the
one under #ifdef CONFIG_ACPI in a separate file, say arch/arm64/kernel/pci-acpi.c ?
Or that you add an #ifdef CONFIG_ACPI around this structure definition?

I can't see anyone using this definition outside ACPI (due to struct acpi_device
dependency) and I would like to avoid it conflicting with other host bridge
drivers trying to define the same name structure.


> +
>  static inline int pci_proc_domain(struct pci_bus *bus)
>  {
>         return 1;
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index 42fb195..cc34ded 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -1,6 +1,10 @@
>  /*
> - * Code borrowed from powerpc/kernel/pci-common.c
> + * Code borrowed from powerpc/kernel/pci-common.c and arch/ia64/pci/pci.c
>   *
> + * Copyright (c) 2002, 2005 Hewlett-Packard Development Company, L.P.
> + *     David Mosberger-Tang <davidm@hpl.hp.com>
> + *     Bjorn Helgaas <bjorn.helgaas@hp.com>
> + * Copyright (C) 2004 Silicon Graphics, Inc.
>   * Copyright (C) 2003 Anton Blanchard <anton@au.ibm.com>, IBM
>   * Copyright (C) 2014 ARM Ltd.
>   *
> @@ -17,10 +21,16 @@
>  #include <linux/mm.h>
>  #include <linux/of_pci.h>
>  #include <linux/of_platform.h>
> +#include <linux/of_address.h>
>  #include <linux/slab.h>
> +#include <linux/pci.h>
> +#include <linux/acpi.h>
> +#include <linux/mmconfig.h>
> 
>  #include <asm/pci-bridge.h>
> 
> +#define PREFIX "PCI: "

Where is this used?

> +
>  /*
>   * Called after each bus is probed, but before its children are examined
>   */
> @@ -43,7 +53,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>   */
>  int pcibios_add_device(struct pci_dev *dev)
>  {
> -       dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
> +       if (acpi_disabled)
> +               dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
> 
>         return 0;
>  }
> @@ -54,45 +65,399 @@ static bool dt_domain_found = false;
> 
>  void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
>  {
> -       int domain = of_get_pci_domain_nr(parent->of_node);
> +       int domain = -1;
> 
> -       if (domain >= 0) {
> -               dt_domain_found = true;
> -       } else if (dt_domain_found == true) {
> -               dev_err(parent, "Node %s is missing \"linux,pci-domain\" property in DT\n",
> -                       parent->of_node->full_name);
> -               return;
> +       if (acpi_disabled) {
> +               domain = of_get_pci_domain_nr(parent->of_node);
> +
> +               if (domain >= 0) {
> +                       dt_domain_found = true;
> +               } else if (dt_domain_found == true) {
> +                       dev_err(parent, "Node %s is missing \"linux,pci-domain\" property in DT\n",
> +                               parent->of_node->full_name);
> +                       return;
> +               } else {
> +                       domain = pci_get_new_domain_nr();
> +               }
>         } else {
> -               domain = pci_get_new_domain_nr();
> +               /*
> +                * Take the domain nr from associated private data.
> +                * Case where bus has parent is covered in pci_alloc_bus()
> +                */
> +               if (!parent)
> +                       domain = PCI_CONTROLLER(bus)->segment;

I would also like to wrap this into an ACPI specific function. Reason for it
is that when I get to split the pci_host_bridge creation out of pci_create_root_bus()
this will become a pci_controller property.

>         }
> 
>         bus->domain_nr = domain;
>  }
>  #endif
> 
> +static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus,
> +                                 unsigned int devfn)
> +{
> +       struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
> +
> +       if (cfg && cfg->virt)
> +               return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
> +       return NULL;
> +}
> +
>  /*
>   * raw_pci_read/write - Platform-specific PCI config space access.
> - *
> - * Default empty implementation.  Replace with an architecture-specific setup
> - * routine, if necessary.
>   */
>  int raw_pci_read(unsigned int domain, unsigned int bus,
>                   unsigned int devfn, int reg, int len, u32 *val)
>  {
> -       return -EINVAL;
> +       char __iomem *addr;
> +
> +       if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
> +err:           *val = -1;

I believe the general usage is to have labels on their own line.

> +               return -EINVAL;
> +       }
> +
> +       rcu_read_lock();
> +       addr = pci_dev_base(domain, bus, devfn);
> +       if (!addr) {
> +               rcu_read_unlock();
> +               goto err;
> +       }
> +
> +       switch (len) {
> +       case 1:
> +               *val = readb(addr + reg);
> +               break;
> +       case 2:
> +               *val = readw(addr + reg);
> +               break;
> +       case 4:
> +               *val = readl(addr + reg);
> +               break;
> +       }
> +       rcu_read_unlock();
> +
> +       return 0;
>  }
> 
>  int raw_pci_write(unsigned int domain, unsigned int bus,
>                 unsigned int devfn, int reg, int len, u32 val)
>  {
> -       return -EINVAL;
> +       char __iomem *addr;
> +
> +       if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
> +               return -EINVAL;
> +
> +       rcu_read_lock();
> +       addr = pci_dev_base(domain, bus, devfn);
> +       if (!addr) {
> +               rcu_read_unlock();
> +               return -EINVAL;
> +       }
> +
> +       switch (len) {
> +       case 1:
> +               writeb(val, addr + reg);
> +               break;
> +       case 2:
> +               writew(val, addr + reg);
> +               break;
> +       case 4:
> +               writel(val, addr + reg);
> +               break;
> +       }
> +       rcu_read_unlock();
> +
> +       return 0;
>  }
> 

These raw_pci_{read,write} functions are all ACPI specific so they can move
into the new file as well.


>  #ifdef CONFIG_ACPI
> +static int pci_read(struct pci_bus *bus, unsigned int devfn, int where,
> +                   int size, u32 *value)
> +{
> +       return raw_pci_read(pci_domain_nr(bus), bus->number,
> +                           devfn, where, size, value);
> +}
> +
> +static int pci_write(struct pci_bus *bus, unsigned int devfn, int where,
> +                    int size, u32 value)
> +{
> +       return raw_pci_write(pci_domain_nr(bus), bus->number,
> +                            devfn, where, size, value);
> +}
> +
> +struct pci_ops pci_root_ops = {
> +       .read = pci_read,
> +       .write = pci_write,
> +};
> +
> +static struct pci_controller *alloc_pci_controller(int seg)
> +{
> +       struct pci_controller *controller;
> +
> +       controller = kzalloc(sizeof(*controller), GFP_KERNEL);
> +       if (!controller)
> +               return NULL;
> +
> +       controller->segment = seg;
> +       return controller;
> +}
> +
> +struct pci_root_info {
> +       struct acpi_device *bridge;
> +       struct pci_controller *controller;
> +       struct list_head resources;
> +       struct resource *res;
> +       resource_size_t *res_offset;

Why do you need to keep an array of res_offsets here? You only seem
to be using the values once when you add the resource to the host
bridge windows.

> +       unsigned int res_num;
> +       char *name;
> +};
> +
> +static acpi_status resource_to_window(struct acpi_resource *resource,
> +                                     struct acpi_resource_address64 *addr)
> +{
> +       acpi_status status;
> +
> +       /*
> +        * We're only interested in _CRS descriptors that are
> +        *      - address space descriptors for memory
> +        *      - non-zero size
> +        *      - producers, i.e., the address space is routed downstream,
> +        *        not consumed by the bridge itself
> +        */
> +       status = acpi_resource_to_address64(resource, addr);
> +       if (ACPI_SUCCESS(status) &&
> +           (addr->resource_type == ACPI_MEMORY_RANGE ||
> +            addr->resource_type == ACPI_IO_RANGE) &&
> +           addr->address_length &&
> +           addr->producer_consumer == ACPI_PRODUCER)
> +               return AE_OK;
> +
> +       return AE_ERROR;
> +}
> +
> +static acpi_status count_window(struct acpi_resource *resource, void *data)
> +{
> +       unsigned int *windows = (unsigned int *) data;
> +       struct acpi_resource_address64 addr;
> +       acpi_status status;
> +
> +       status = resource_to_window(resource, &addr);
> +       if (ACPI_SUCCESS(status))
> +               (*windows)++;
> +
> +       return AE_OK;
> +}
> +
> +static acpi_status add_window(struct acpi_resource *res, void *data)
> +{
> +       struct pci_root_info *info = data;
> +       struct resource *resource;
> +       struct acpi_resource_address64 addr;
> +       acpi_status status;
> +       unsigned long flags;
> +       struct resource *root;
> +       u64 start;
> +
> +       /* Return AE_OK for non-window resources to keep scanning for more */
> +       status = resource_to_window(res, &addr);
> +       if (!ACPI_SUCCESS(status))
> +               return AE_OK;
> +
> +       if (addr.resource_type == ACPI_MEMORY_RANGE) {
> +               flags = IORESOURCE_MEM;
> +               root = &iomem_resource;
> +       } else if (addr.resource_type == ACPI_IO_RANGE) {
> +               flags = IORESOURCE_IO;
> +               root = &ioport_resource;
> +       } else
> +               return AE_OK;
> +
> +       start = addr.minimum + addr.translation_offset;
> +
> +       resource = &info->res[info->res_num];
> +       resource->name = info->name;
> +       resource->flags = flags;
> +       resource->start = start;
> +       resource->end = resource->start + addr.address_length - 1;
> +
> +       if (flags & IORESOURCE_IO) {
> +               unsigned long port;
> +               int err;
> +
> +               err = pci_register_io_range(start, addr.address_length);
> +               if (err)
> +                       return AE_OK;
> +
> +               port = pci_address_to_pio(start);
> +               if (port == (unsigned long)-1)
> +                       return AE_OK;
> +
> +               resource->start = port;
> +               resource->end = port + addr.address_length - 1;
> +
> +               if (pci_remap_iospace(resource, start) < 0)
> +                       return AE_OK;

You seem to leave around invalid resources every time you return in this code
path due to your choice of ignoring error conditions.

I think there are a few things that can be streamlined in this patch, but
overall I think it looks promising.

Best regards,
Liviu


> +
> +               info->res_offset[info->res_num] = 0;
> +       } else
> +               info->res_offset[info->res_num] = addr.translation_offset;
> +
> +       if (insert_resource(root, resource)) {
> +               dev_err(&info->bridge->dev,
> +                       "can't allocate host bridge window %pR\n",
> +                       resource);
> +       } else {
> +               if (addr.translation_offset)
> +                       dev_info(&info->bridge->dev, "host bridge window %pR "
> +                                "(PCI address [%#llx-%#llx])\n",
> +                                resource,
> +                                resource->start - addr.translation_offset,
> +                                resource->end - addr.translation_offset);
> +               else
> +                       dev_info(&info->bridge->dev,
> +                                "host bridge window %pR\n", resource);
> +       }
> +
> +       pci_add_resource_offset(&info->resources, resource,
> +                               info->res_offset[info->res_num]);
> +       info->res_num++;
> +       return AE_OK;
> +}
> +
> +static void free_pci_root_info_res(struct pci_root_info *info)
> +{
> +       kfree(info->name);
> +       kfree(info->res);
> +       info->res = NULL;
> +       kfree(info->res_offset);
> +       info->res_offset = NULL;
> +       info->res_num = 0;
> +       kfree(info->controller);
> +       info->controller = NULL;
> +}
> +
> +static void __release_pci_root_info(struct pci_root_info *info)
> +{
> +       int i;
> +       struct resource *res;
> +
> +       for (i = 0; i < info->res_num; i++) {
> +               res = &info->res[i];
> +
> +               if (!res->parent)
> +                       continue;
> +
> +               if (!(res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
> +                       continue;
> +
> +               release_resource(res);
> +       }
> +
> +       free_pci_root_info_res(info);
> +       kfree(info);
> +}
> +
> +static void release_pci_root_info(struct pci_host_bridge *bridge)
> +{
> +       struct pci_root_info *info = bridge->release_data;
> +
> +       __release_pci_root_info(info);
> +}
> +
> +static int
> +probe_pci_root_info(struct pci_root_info *info, struct acpi_device *device,
> +               int busnum, int domain)
> +{
> +       char *name;
> +
> +       name = kmalloc(16, GFP_KERNEL);
> +       if (!name)
> +               return -ENOMEM;
> +
> +       sprintf(name, "PCI Bus %04x:%02x", domain, busnum);
> +       info->bridge = device;
> +       info->name = name;
> +
> +       acpi_walk_resources(device->handle, METHOD_NAME__CRS, count_window,
> +                       &info->res_num);
> +       if (info->res_num) {
> +               info->res =
> +                       kzalloc_node(sizeof(*info->res) * info->res_num,
> +                                    GFP_KERNEL, info->controller->node);
> +               if (!info->res) {
> +                       kfree(name);
> +                       return -ENOMEM;
> +               }
> +
> +               info->res_offset =
> +                       kzalloc_node(sizeof(*info->res_offset) * info->res_num,
> +                                       GFP_KERNEL, info->controller->node);
> +               if (!info->res_offset) {
> +                       kfree(name);
> +                       kfree(info->res);
> +                       info->res = NULL;
> +                       return -ENOMEM;
> +               }
> +
> +               info->res_num = 0;
> +               acpi_walk_resources(device->handle, METHOD_NAME__CRS,
> +                       add_window, info);
> +       } else
> +               kfree(name);
> +
> +       return 0;
> +}
> +
>  /* Root bridge scanning */
>  struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  {
> -       /* TODO: Should be revisited when implementing PCI on ACPI */
> -       return NULL;
> +       struct acpi_device *device = root->device;
> +       int domain = root->segment;
> +       int bus = root->secondary.start;
> +       struct pci_controller *controller;
> +       struct pci_root_info *info = NULL;
> +       int busnum = root->secondary.start;
> +       struct pci_bus *pbus;
> +       int ret;
> +
> +       controller = alloc_pci_controller(domain);
> +       if (!controller)
> +               return NULL;
> +
> +       controller->companion = device;
> +       controller->node = acpi_get_node(device->handle);
> +
> +       info = kzalloc(sizeof(*info), GFP_KERNEL);
> +       if (!info) {
> +               dev_err(&device->dev,
> +                               "pci_bus %04x:%02x: ignored (out of memory)\n",
> +                               domain, busnum);
> +               kfree(controller);
> +               return NULL;
> +       }
> +
> +       info->controller = controller;
> +       INIT_LIST_HEAD(&info->resources);
> +
> +       ret = probe_pci_root_info(info, device, busnum, domain);
> +       if (ret) {
> +               kfree(info->controller);
> +               kfree(info);
> +               return NULL;
> +       }
> +       /* insert busn resource at first */
> +       pci_add_resource(&info->resources, &root->secondary);
> +
> +       pbus = pci_create_root_bus(NULL, bus, &pci_root_ops, controller,
> +                                  &info->resources);
> +       if (!pbus) {
> +               pci_free_resource_list(&info->resources);
> +               __release_pci_root_info(info);
> +               return NULL;
> +       }
> +
> +       pci_set_host_bridge_release(to_pci_host_bridge(pbus->bridge),
> +                       release_pci_root_info, info);
> +       pci_scan_child_bus(pbus);
> +       return pbus;
>  }
> -#endif
> +#endif /* CONFIG_ACPI */
> --
> 1.9.1
> 
>
Tomasz Nowicki Nov. 12, 2014, 8:47 a.m. UTC | #3
W dniu 07.11.2014 o 15:55, Liviu Dudau pisze:
> On Fri, Nov 07, 2014 at 01:27:56PM +0000, Tomasz Nowicki wrote:
>> Code inspired by arch/x86/pci/acpi.c and arch/ia64/pci/pci.c files.
>> The main reasons why we need this:
>> - parse and manage resources (BUS, IO and MEM)
>> - create pci root bus and enumerate its children
>> - provide PCI config space accessors (via MMCONFIG)
>
> Hi Tomasz,
>
> I have some comments to your code:
>
>>
>> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
>> ---
>>   arch/arm64/include/asm/pci.h |   8 +
>>   arch/arm64/kernel/pci.c      | 401 +++++++++++++++++++++++++++++++++++++++++--
>>   2 files changed, 391 insertions(+), 18 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
>> index fded096..ecd940f 100644
>> --- a/arch/arm64/include/asm/pci.h
>> +++ b/arch/arm64/include/asm/pci.h
>> @@ -33,6 +33,14 @@ static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
>>   extern int isa_dma_bridge_buggy;
>>
>>   #ifdef CONFIG_PCI
>> +struct pci_controller {
>> +       struct acpi_device *companion;
>> +       int segment;
>> +       int node;               /* nearest node with memory or NUMA_NO_NODE for global allocation */
>> +};
>> +
>> +#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
>
> I am trying to move away from the model where the architecture dictates the shape
> of the pci_controller structure. Can I suggest that you put all this code and the
> one under #ifdef CONFIG_ACPI in a separate file, say arch/arm64/kernel/pci-acpi.c ?
> Or that you add an #ifdef CONFIG_ACPI around this structure definition?
>
> I can't see anyone using this definition outside ACPI (due to struct acpi_device
> dependency) and I would like to avoid it conflicting with other host bridge
> drivers trying to define the same name structure.

That is good point, will do, thanks.

>
>
>> +
>>   static inline int pci_proc_domain(struct pci_bus *bus)
>>   {
>>          return 1;
>> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
>> index 42fb195..cc34ded 100644
>> --- a/arch/arm64/kernel/pci.c
>> +++ b/arch/arm64/kernel/pci.c
>> @@ -1,6 +1,10 @@
>>   /*
>> - * Code borrowed from powerpc/kernel/pci-common.c
>> + * Code borrowed from powerpc/kernel/pci-common.c and arch/ia64/pci/pci.c
>>    *
>> + * Copyright (c) 2002, 2005 Hewlett-Packard Development Company, L.P.
>> + *     David Mosberger-Tang <davidm@hpl.hp.com>
>> + *     Bjorn Helgaas <bjorn.helgaas@hp.com>
>> + * Copyright (C) 2004 Silicon Graphics, Inc.
>>    * Copyright (C) 2003 Anton Blanchard <anton@au.ibm.com>, IBM
>>    * Copyright (C) 2014 ARM Ltd.
>>    *
>> @@ -17,10 +21,16 @@
>>   #include <linux/mm.h>
>>   #include <linux/of_pci.h>
>>   #include <linux/of_platform.h>
>> +#include <linux/of_address.h>
>>   #include <linux/slab.h>
>> +#include <linux/pci.h>
>> +#include <linux/acpi.h>
>> +#include <linux/mmconfig.h>
>>
>>   #include <asm/pci-bridge.h>
>>
>> +#define PREFIX "PCI: "
>
> Where is this used?

Nowhere here, will remove/improve.

>
>> +
>>   /*
>>    * Called after each bus is probed, but before its children are examined
>>    */
>> @@ -43,7 +53,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>>    */
>>   int pcibios_add_device(struct pci_dev *dev)
>>   {
>> -       dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
>> +       if (acpi_disabled)
>> +               dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
>>
>>          return 0;
>>   }
>> @@ -54,45 +65,399 @@ static bool dt_domain_found = false;
>>
>>   void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
>>   {
>> -       int domain = of_get_pci_domain_nr(parent->of_node);
>> +       int domain = -1;
>>
>> -       if (domain >= 0) {
>> -               dt_domain_found = true;
>> -       } else if (dt_domain_found == true) {
>> -               dev_err(parent, "Node %s is missing \"linux,pci-domain\" property in DT\n",
>> -                       parent->of_node->full_name);
>> -               return;
>> +       if (acpi_disabled) {
>> +               domain = of_get_pci_domain_nr(parent->of_node);
>> +
>> +               if (domain >= 0) {
>> +                       dt_domain_found = true;
>> +               } else if (dt_domain_found == true) {
>> +                       dev_err(parent, "Node %s is missing \"linux,pci-domain\" property in DT\n",
>> +                               parent->of_node->full_name);
>> +                       return;
>> +               } else {
>> +                       domain = pci_get_new_domain_nr();
>> +               }
>>          } else {
>> -               domain = pci_get_new_domain_nr();
>> +               /*
>> +                * Take the domain nr from associated private data.
>> +                * Case where bus has parent is covered in pci_alloc_bus()
>> +                */
>> +               if (!parent)
>> +                       domain = PCI_CONTROLLER(bus)->segment;
>
> I would also like to wrap this into an ACPI specific function. Reason for it
> is that when I get to split the pci_host_bridge creation out of pci_create_root_bus()
> this will become a pci_controller property.

Make sense for me.

>
>>          }
>>
>>          bus->domain_nr = domain;
>>   }
>>   #endif
>>
>> +static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus,
>> +                                 unsigned int devfn)
>> +{
>> +       struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
>> +
>> +       if (cfg && cfg->virt)
>> +               return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
>> +       return NULL;
>> +}
>> +
>>   /*
>>    * raw_pci_read/write - Platform-specific PCI config space access.
>> - *
>> - * Default empty implementation.  Replace with an architecture-specific setup
>> - * routine, if necessary.
>>    */
>>   int raw_pci_read(unsigned int domain, unsigned int bus,
>>                    unsigned int devfn, int reg, int len, u32 *val)
>>   {
>> -       return -EINVAL;
>> +       char __iomem *addr;
>> +
>> +       if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
>> +err:           *val = -1;
>
> I believe the general usage is to have labels on their own line.
>
>> +               return -EINVAL;
>> +       }
>> +
>> +       rcu_read_lock();
>> +       addr = pci_dev_base(domain, bus, devfn);
>> +       if (!addr) {
>> +               rcu_read_unlock();
>> +               goto err;
>> +       }
>> +
>> +       switch (len) {
>> +       case 1:
>> +               *val = readb(addr + reg);
>> +               break;
>> +       case 2:
>> +               *val = readw(addr + reg);
>> +               break;
>> +       case 4:
>> +               *val = readl(addr + reg);
>> +               break;
>> +       }
>> +       rcu_read_unlock();
>> +
>> +       return 0;
>>   }
>>
>>   int raw_pci_write(unsigned int domain, unsigned int bus,
>>                  unsigned int devfn, int reg, int len, u32 val)
>>   {
>> -       return -EINVAL;
>> +       char __iomem *addr;
>> +
>> +       if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
>> +               return -EINVAL;
>> +
>> +       rcu_read_lock();
>> +       addr = pci_dev_base(domain, bus, devfn);
>> +       if (!addr) {
>> +               rcu_read_unlock();
>> +               return -EINVAL;
>> +       }
>> +
>> +       switch (len) {
>> +       case 1:
>> +               writeb(val, addr + reg);
>> +               break;
>> +       case 2:
>> +               writew(val, addr + reg);
>> +               break;
>> +       case 4:
>> +               writel(val, addr + reg);
>> +               break;
>> +       }
>> +       rcu_read_unlock();
>> +
>> +       return 0;
>>   }
>>
>
> These raw_pci_{read,write} functions are all ACPI specific so they can move
> into the new file as well.

Got it!

>
>
>>   #ifdef CONFIG_ACPI
>> +static int pci_read(struct pci_bus *bus, unsigned int devfn, int where,
>> +                   int size, u32 *value)
>> +{
>> +       return raw_pci_read(pci_domain_nr(bus), bus->number,
>> +                           devfn, where, size, value);
>> +}
>> +
>> +static int pci_write(struct pci_bus *bus, unsigned int devfn, int where,
>> +                    int size, u32 value)
>> +{
>> +       return raw_pci_write(pci_domain_nr(bus), bus->number,
>> +                            devfn, where, size, value);
>> +}
>> +
>> +struct pci_ops pci_root_ops = {
>> +       .read = pci_read,
>> +       .write = pci_write,
>> +};
>> +
>> +static struct pci_controller *alloc_pci_controller(int seg)
>> +{
>> +       struct pci_controller *controller;
>> +
>> +       controller = kzalloc(sizeof(*controller), GFP_KERNEL);
>> +       if (!controller)
>> +               return NULL;
>> +
>> +       controller->segment = seg;
>> +       return controller;
>> +}
>> +
>> +struct pci_root_info {
>> +       struct acpi_device *bridge;
>> +       struct pci_controller *controller;
>> +       struct list_head resources;
>> +       struct resource *res;
>> +       resource_size_t *res_offset;
>
> Why do you need to keep an array of res_offsets here? You only seem
> to be using the values once when you add the resource to the host
> bridge windows.

This is what I noticed too but did not improve that at the end. Let me 
fix that in the next ver.

>
>> +       unsigned int res_num;
>> +       char *name;
>> +};
>> +
>> +static acpi_status resource_to_window(struct acpi_resource *resource,
>> +                                     struct acpi_resource_address64 *addr)
>> +{
>> +       acpi_status status;
>> +
>> +       /*
>> +        * We're only interested in _CRS descriptors that are
>> +        *      - address space descriptors for memory
>> +        *      - non-zero size
>> +        *      - producers, i.e., the address space is routed downstream,
>> +        *        not consumed by the bridge itself
>> +        */
>> +       status = acpi_resource_to_address64(resource, addr);
>> +       if (ACPI_SUCCESS(status) &&
>> +           (addr->resource_type == ACPI_MEMORY_RANGE ||
>> +            addr->resource_type == ACPI_IO_RANGE) &&
>> +           addr->address_length &&
>> +           addr->producer_consumer == ACPI_PRODUCER)
>> +               return AE_OK;
>> +
>> +       return AE_ERROR;
>> +}
>> +
>> +static acpi_status count_window(struct acpi_resource *resource, void *data)
>> +{
>> +       unsigned int *windows = (unsigned int *) data;
>> +       struct acpi_resource_address64 addr;
>> +       acpi_status status;
>> +
>> +       status = resource_to_window(resource, &addr);
>> +       if (ACPI_SUCCESS(status))
>> +               (*windows)++;
>> +
>> +       return AE_OK;
>> +}
>> +
>> +static acpi_status add_window(struct acpi_resource *res, void *data)
>> +{
>> +       struct pci_root_info *info = data;
>> +       struct resource *resource;
>> +       struct acpi_resource_address64 addr;
>> +       acpi_status status;
>> +       unsigned long flags;
>> +       struct resource *root;
>> +       u64 start;
>> +
>> +       /* Return AE_OK for non-window resources to keep scanning for more */
>> +       status = resource_to_window(res, &addr);
>> +       if (!ACPI_SUCCESS(status))
>> +               return AE_OK;
>> +
>> +       if (addr.resource_type == ACPI_MEMORY_RANGE) {
>> +               flags = IORESOURCE_MEM;
>> +               root = &iomem_resource;
>> +       } else if (addr.resource_type == ACPI_IO_RANGE) {
>> +               flags = IORESOURCE_IO;
>> +               root = &ioport_resource;
>> +       } else
>> +               return AE_OK;
>> +
>> +       start = addr.minimum + addr.translation_offset;
>> +
>> +       resource = &info->res[info->res_num];
>> +       resource->name = info->name;
>> +       resource->flags = flags;
>> +       resource->start = start;
>> +       resource->end = resource->start + addr.address_length - 1;
>> +
>> +       if (flags & IORESOURCE_IO) {
>> +               unsigned long port;
>> +               int err;
>> +
>> +               err = pci_register_io_range(start, addr.address_length);
>> +               if (err)
>> +                       return AE_OK;
>> +
>> +               port = pci_address_to_pio(start);
>> +               if (port == (unsigned long)-1)
>> +                       return AE_OK;
>> +
>> +               resource->start = port;
>> +               resource->end = port + addr.address_length - 1;
>> +
>> +               if (pci_remap_iospace(resource, start) < 0)
>> +                       return AE_OK;
>
> You seem to leave around invalid resources every time you return in this code
> path due to your choice of ignoring error conditions.
>
> I think there are a few things that can be streamlined in this patch, but
> overall I think it looks promising.
>

Thanks Liviu!

Tomasz
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Tomasz Nowicki Nov. 14, 2014, 2:10 p.m. UTC | #4
On 07.11.2014 15:24, Arnd Bergmann wrote:
> On Friday 07 November 2014 14:27:56 Tomasz Nowicki wrote:
>>
>>   #ifdef CONFIG_PCI
>> +struct pci_controller {
>> +	struct acpi_device *companion;
>> +	int segment;
>> +	int node;		/* nearest node with memory or NUMA_NO_NODE for global allocation */
>> +};
>> +
>> +#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
>> +
>
> Don't use busdev->sysdata in architecture specific code, it belongs to the
> host bridge driver with the new model. For ACPI you don't have a host bridge
> driver, but it's better to keep these separate.
>
> The segment is always the same as the domain number, so just use that.
> The node and companion members here can get added to struct pci_host_bridge.

The reason why I put segment field to struct pci_controller is to 
initialize domain_nr of struct pci_bus being in pci_create_root_bus(), 
domain_nr can be used later on though. Correct me I am wrong.

Honestly I do not see the way to create root bus without e.g. 
sysdata.segment here.

>
>> @@ -43,7 +53,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>>    */
>>   int pcibios_add_device(struct pci_dev *dev)
>>   {
>> -	dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
>> +	if (acpi_disabled)
>> +		dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
>>
>>   	return 0;
>>   }
>
> How do you assign the irq number with ACPI? Do you only support MSI?

I missed that, will add in next ver.

>
>>   /*
>>    * raw_pci_read/write - Platform-specific PCI config space access.
>> - *
>> - * Default empty implementation.  Replace with an architecture-specific setup
>> - * routine, if necessary.
>>    */
>>   int raw_pci_read(unsigned int domain, unsigned int bus,
>>   		  unsigned int devfn, int reg, int len, u32 *val)
>>   {
>> -	return -EINVAL;
>> +	char __iomem *addr;
>> +
>> +	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
>> +err:		*val = -1;
>> +		return -EINVAL;
>> +	}
>> +
>> +	rcu_read_lock();
>> +	addr = pci_dev_base(domain, bus, devfn);
>> +	if (!addr) {
>> +		rcu_read_unlock();
>> +		goto err;
>> +	}
>
> The config space accessors should probably be shared with
> drivers/pci/host/pci-host-generic.c, e.g. by moving the rest of
> the new code in there as well, or by moving the config space
> accessors from that file to drivers/pci/mmconfig.c.

Tomasz
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Arnd Bergmann Nov. 14, 2014, 2:53 p.m. UTC | #5
On Friday 14 November 2014 15:10:12 Tomasz Nowicki wrote:
> On 07.11.2014 15:24, Arnd Bergmann wrote:
> > On Friday 07 November 2014 14:27:56 Tomasz Nowicki wrote:
> >>
> >>   #ifdef CONFIG_PCI
> >> +struct pci_controller {
> >> +	struct acpi_device *companion;
> >> +	int segment;
> >> +	int node;		/* nearest node with memory or NUMA_NO_NODE for global allocation */
> >> +};
> >> +
> >> +#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
> >> +
> >
> > Don't use busdev->sysdata in architecture specific code, it belongs to the
> > host bridge driver with the new model. For ACPI you don't have a host bridge
> > driver, but it's better to keep these separate.
> >
> > The segment is always the same as the domain number, so just use that.
> > The node and companion members here can get added to struct pci_host_bridge.
> 
> The reason why I put segment field to struct pci_controller is to 
> initialize domain_nr of struct pci_bus being in pci_create_root_bus(), 
> domain_nr can be used later on though. Correct me I am wrong.
> 
> Honestly I do not see the way to create root bus without e.g. 
> sysdata.segment here.

See the patches that Liviu and Lorenzo have been posting recently. This
should be straightforward in 3.19.

	Arnd
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Tomasz Nowicki Nov. 18, 2014, 10:17 a.m. UTC | #6
On 14.11.2014 15:53, Arnd Bergmann wrote:
> On Friday 14 November 2014 15:10:12 Tomasz Nowicki wrote:
>> On 07.11.2014 15:24, Arnd Bergmann wrote:
>>> On Friday 07 November 2014 14:27:56 Tomasz Nowicki wrote:
>>>>
>>>>    #ifdef CONFIG_PCI
>>>> +struct pci_controller {
>>>> +	struct acpi_device *companion;
>>>> +	int segment;
>>>> +	int node;		/* nearest node with memory or NUMA_NO_NODE for global allocation */
>>>> +};
>>>> +
>>>> +#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
>>>> +
>>>
>>> Don't use busdev->sysdata in architecture specific code, it belongs to the
>>> host bridge driver with the new model. For ACPI you don't have a host bridge
>>> driver, but it's better to keep these separate.
>>>
>>> The segment is always the same as the domain number, so just use that.
>>> The node and companion members here can get added to struct pci_host_bridge.
>>
>> The reason why I put segment field to struct pci_controller is to
>> initialize domain_nr of struct pci_bus being in pci_create_root_bus(),
>> domain_nr can be used later on though. Correct me I am wrong.
>>
>> Honestly I do not see the way to create root bus without e.g.
>> sysdata.segment here.
>
> See the patches that Liviu and Lorenzo have been posting recently. This
> should be straightforward in 3.19.

Hi Arnd,

I have been looking into patch (if that what you meant) :
[RFC PATCH v2] drivers: pci: move PCI domain assignment to generic PCI code

This is not enough for me since it gets domain number from its OF parent 
or just uses sequential increased domain number. In my case, I do not 
have parent so I need to get segment from ACPI node which is not 
available there.

On the other hand, patch set posted by Wang Yijing:
[RFC PATCH 00/16] Refine PCI host bridge scan interfaces
tends to solve that issue.

What would be the best way for this patch, keep busdev->sysdata usage 
and rebase once Wang Yijing patch set will be accepted?

Regards,
Tomasz



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Arnd Bergmann Nov. 18, 2014, 10:35 a.m. UTC | #7
On Tuesday 18 November 2014 11:17:10 Tomasz Nowicki wrote:
> On 14.11.2014 15:53, Arnd Bergmann wrote:
> > On Friday 14 November 2014 15:10:12 Tomasz Nowicki wrote:
> >> On 07.11.2014 15:24, Arnd Bergmann wrote:
> >>> On Friday 07 November 2014 14:27:56 Tomasz Nowicki wrote:
> >>>>
> >>>>    #ifdef CONFIG_PCI
> >>>> +struct pci_controller {
> >>>> +  struct acpi_device *companion;
> >>>> +  int segment;
> >>>> +  int node;               /* nearest node with memory or NUMA_NO_NODE for global allocation */
> >>>> +};
> >>>> +
> >>>> +#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
> >>>> +
> >>>
> >>> Don't use busdev->sysdata in architecture specific code, it belongs to the
> >>> host bridge driver with the new model. For ACPI you don't have a host bridge
> >>> driver, but it's better to keep these separate.
> >>>
> >>> The segment is always the same as the domain number, so just use that.
> >>> The node and companion members here can get added to struct pci_host_bridge.
> >>
> >> The reason why I put segment field to struct pci_controller is to
> >> initialize domain_nr of struct pci_bus being in pci_create_root_bus(),
> >> domain_nr can be used later on though. Correct me I am wrong.
> >>
> >> Honestly I do not see the way to create root bus without e.g.
> >> sysdata.segment here.
> >
> > See the patches that Liviu and Lorenzo have been posting recently. This
> > should be straightforward in 3.19.
> 
> Hi Arnd,
> 
> I have been looking into patch (if that what you meant) :
> [RFC PATCH v2] drivers: pci: move PCI domain assignment to generic PCI code
> 
> This is not enough for me since it gets domain number from its OF parent 
> or just uses sequential increased domain number. In my case, I do not 
> have parent so I need to get segment from ACPI node which is not 
> available there.
> 
> On the other hand, patch set posted by Wang Yijing:
> [RFC PATCH 00/16] Refine PCI host bridge scan interfaces
> tends to solve that issue.
> 
> What would be the best way for this patch, keep busdev->sysdata usage 
> and rebase once Wang Yijing patch set will be accepted?

I think the "Refine PCI host bridge scan interfaces" series is still in an
early stage, you may need something sooner than that.

What I meant is that with "drivers: pci: move PCI domain assignment to
generic PCI code", we already have a way to put the domain number into
'struct pci_bus' and retrieve it from there without ever consulting
the sysdata pointer. You should build on top of that and do it the same
way. Of course you will have to put it in there differently, but you can
get it out the same way.

	Arnd
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diff mbox

Patch

diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
index fded096..ecd940f 100644
--- a/arch/arm64/include/asm/pci.h
+++ b/arch/arm64/include/asm/pci.h
@@ -33,6 +33,14 @@  static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
 extern int isa_dma_bridge_buggy;
 
 #ifdef CONFIG_PCI
+struct pci_controller {
+	struct acpi_device *companion;
+	int segment;
+	int node;		/* nearest node with memory or NUMA_NO_NODE for global allocation */
+};
+
+#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
+
 static inline int pci_proc_domain(struct pci_bus *bus)
 {
 	return 1;
diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 42fb195..cc34ded 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -1,6 +1,10 @@ 
 /*
- * Code borrowed from powerpc/kernel/pci-common.c
+ * Code borrowed from powerpc/kernel/pci-common.c and arch/ia64/pci/pci.c
  *
+ * Copyright (c) 2002, 2005 Hewlett-Packard Development Company, L.P.
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ *	Bjorn Helgaas <bjorn.helgaas@hp.com>
+ * Copyright (C) 2004 Silicon Graphics, Inc.
  * Copyright (C) 2003 Anton Blanchard <anton@au.ibm.com>, IBM
  * Copyright (C) 2014 ARM Ltd.
  *
@@ -17,10 +21,16 @@ 
 #include <linux/mm.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
+#include <linux/of_address.h>
 #include <linux/slab.h>
+#include <linux/pci.h>
+#include <linux/acpi.h>
+#include <linux/mmconfig.h>
 
 #include <asm/pci-bridge.h>
 
+#define PREFIX "PCI: "
+
 /*
  * Called after each bus is probed, but before its children are examined
  */
@@ -43,7 +53,8 @@  resource_size_t pcibios_align_resource(void *data, const struct resource *res,
  */
 int pcibios_add_device(struct pci_dev *dev)
 {
-	dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
+	if (acpi_disabled)
+		dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
 
 	return 0;
 }
@@ -54,45 +65,399 @@  static bool dt_domain_found = false;
 
 void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
 {
-	int domain = of_get_pci_domain_nr(parent->of_node);
+	int domain = -1;
 
-	if (domain >= 0) {
-		dt_domain_found = true;
-	} else if (dt_domain_found == true) {
-		dev_err(parent, "Node %s is missing \"linux,pci-domain\" property in DT\n",
-			parent->of_node->full_name);
-		return;
+	if (acpi_disabled) {
+		domain = of_get_pci_domain_nr(parent->of_node);
+
+		if (domain >= 0) {
+			dt_domain_found = true;
+		} else if (dt_domain_found == true) {
+			dev_err(parent, "Node %s is missing \"linux,pci-domain\" property in DT\n",
+				parent->of_node->full_name);
+			return;
+		} else {
+			domain = pci_get_new_domain_nr();
+		}
 	} else {
-		domain = pci_get_new_domain_nr();
+		/*
+		 * Take the domain nr from associated private data.
+		 * Case where bus has parent is covered in pci_alloc_bus()
+		 */
+		if (!parent)
+			domain = PCI_CONTROLLER(bus)->segment;
 	}
 
 	bus->domain_nr = domain;
 }
 #endif
 
+static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus,
+				  unsigned int devfn)
+{
+	struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
+
+	if (cfg && cfg->virt)
+		return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
+	return NULL;
+}
+
 /*
  * raw_pci_read/write - Platform-specific PCI config space access.
- *
- * Default empty implementation.  Replace with an architecture-specific setup
- * routine, if necessary.
  */
 int raw_pci_read(unsigned int domain, unsigned int bus,
 		  unsigned int devfn, int reg, int len, u32 *val)
 {
-	return -EINVAL;
+	char __iomem *addr;
+
+	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
+err:		*val = -1;
+		return -EINVAL;
+	}
+
+	rcu_read_lock();
+	addr = pci_dev_base(domain, bus, devfn);
+	if (!addr) {
+		rcu_read_unlock();
+		goto err;
+	}
+
+	switch (len) {
+	case 1:
+		*val = readb(addr + reg);
+		break;
+	case 2:
+		*val = readw(addr + reg);
+		break;
+	case 4:
+		*val = readl(addr + reg);
+		break;
+	}
+	rcu_read_unlock();
+
+	return 0;
 }
 
 int raw_pci_write(unsigned int domain, unsigned int bus,
 		unsigned int devfn, int reg, int len, u32 val)
 {
-	return -EINVAL;
+	char __iomem *addr;
+
+	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
+		return -EINVAL;
+
+	rcu_read_lock();
+	addr = pci_dev_base(domain, bus, devfn);
+	if (!addr) {
+		rcu_read_unlock();
+		return -EINVAL;
+	}
+
+	switch (len) {
+	case 1:
+		writeb(val, addr + reg);
+		break;
+	case 2:
+		writew(val, addr + reg);
+		break;
+	case 4:
+		writel(val, addr + reg);
+		break;
+	}
+	rcu_read_unlock();
+
+	return 0;
 }
 
 #ifdef CONFIG_ACPI
+static int pci_read(struct pci_bus *bus, unsigned int devfn, int where,
+		    int size, u32 *value)
+{
+	return raw_pci_read(pci_domain_nr(bus), bus->number,
+			    devfn, where, size, value);
+}
+
+static int pci_write(struct pci_bus *bus, unsigned int devfn, int where,
+		     int size, u32 value)
+{
+	return raw_pci_write(pci_domain_nr(bus), bus->number,
+			     devfn, where, size, value);
+}
+
+struct pci_ops pci_root_ops = {
+	.read = pci_read,
+	.write = pci_write,
+};
+
+static struct pci_controller *alloc_pci_controller(int seg)
+{
+	struct pci_controller *controller;
+
+	controller = kzalloc(sizeof(*controller), GFP_KERNEL);
+	if (!controller)
+		return NULL;
+
+	controller->segment = seg;
+	return controller;
+}
+
+struct pci_root_info {
+	struct acpi_device *bridge;
+	struct pci_controller *controller;
+	struct list_head resources;
+	struct resource *res;
+	resource_size_t *res_offset;
+	unsigned int res_num;
+	char *name;
+};
+
+static acpi_status resource_to_window(struct acpi_resource *resource,
+				      struct acpi_resource_address64 *addr)
+{
+	acpi_status status;
+
+	/*
+	 * We're only interested in _CRS descriptors that are
+	 *	- address space descriptors for memory
+	 *	- non-zero size
+	 *	- producers, i.e., the address space is routed downstream,
+	 *	  not consumed by the bridge itself
+	 */
+	status = acpi_resource_to_address64(resource, addr);
+	if (ACPI_SUCCESS(status) &&
+	    (addr->resource_type == ACPI_MEMORY_RANGE ||
+	     addr->resource_type == ACPI_IO_RANGE) &&
+	    addr->address_length &&
+	    addr->producer_consumer == ACPI_PRODUCER)
+		return AE_OK;
+
+	return AE_ERROR;
+}
+
+static acpi_status count_window(struct acpi_resource *resource, void *data)
+{
+	unsigned int *windows = (unsigned int *) data;
+	struct acpi_resource_address64 addr;
+	acpi_status status;
+
+	status = resource_to_window(resource, &addr);
+	if (ACPI_SUCCESS(status))
+		(*windows)++;
+
+	return AE_OK;
+}
+
+static acpi_status add_window(struct acpi_resource *res, void *data)
+{
+	struct pci_root_info *info = data;
+	struct resource *resource;
+	struct acpi_resource_address64 addr;
+	acpi_status status;
+	unsigned long flags;
+	struct resource *root;
+	u64 start;
+
+	/* Return AE_OK for non-window resources to keep scanning for more */
+	status = resource_to_window(res, &addr);
+	if (!ACPI_SUCCESS(status))
+		return AE_OK;
+
+	if (addr.resource_type == ACPI_MEMORY_RANGE) {
+		flags = IORESOURCE_MEM;
+		root = &iomem_resource;
+	} else if (addr.resource_type == ACPI_IO_RANGE) {
+		flags = IORESOURCE_IO;
+		root = &ioport_resource;
+	} else
+		return AE_OK;
+
+	start = addr.minimum + addr.translation_offset;
+
+	resource = &info->res[info->res_num];
+	resource->name = info->name;
+	resource->flags = flags;
+	resource->start = start;
+	resource->end = resource->start + addr.address_length - 1;
+
+	if (flags & IORESOURCE_IO) {
+		unsigned long port;
+		int err;
+
+		err = pci_register_io_range(start, addr.address_length);
+		if (err)
+			return AE_OK;
+
+		port = pci_address_to_pio(start);
+		if (port == (unsigned long)-1)
+			return AE_OK;
+
+		resource->start = port;
+		resource->end = port + addr.address_length - 1;
+
+		if (pci_remap_iospace(resource, start) < 0)
+			return AE_OK;
+
+		info->res_offset[info->res_num] = 0;
+	} else
+		info->res_offset[info->res_num] = addr.translation_offset;
+
+	if (insert_resource(root, resource)) {
+		dev_err(&info->bridge->dev,
+			"can't allocate host bridge window %pR\n",
+			resource);
+	} else {
+		if (addr.translation_offset)
+			dev_info(&info->bridge->dev, "host bridge window %pR "
+				 "(PCI address [%#llx-%#llx])\n",
+				 resource,
+				 resource->start - addr.translation_offset,
+				 resource->end - addr.translation_offset);
+		else
+			dev_info(&info->bridge->dev,
+				 "host bridge window %pR\n", resource);
+	}
+
+	pci_add_resource_offset(&info->resources, resource,
+				info->res_offset[info->res_num]);
+	info->res_num++;
+	return AE_OK;
+}
+
+static void free_pci_root_info_res(struct pci_root_info *info)
+{
+	kfree(info->name);
+	kfree(info->res);
+	info->res = NULL;
+	kfree(info->res_offset);
+	info->res_offset = NULL;
+	info->res_num = 0;
+	kfree(info->controller);
+	info->controller = NULL;
+}
+
+static void __release_pci_root_info(struct pci_root_info *info)
+{
+	int i;
+	struct resource *res;
+
+	for (i = 0; i < info->res_num; i++) {
+		res = &info->res[i];
+
+		if (!res->parent)
+			continue;
+
+		if (!(res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
+			continue;
+
+		release_resource(res);
+	}
+
+	free_pci_root_info_res(info);
+	kfree(info);
+}
+
+static void release_pci_root_info(struct pci_host_bridge *bridge)
+{
+	struct pci_root_info *info = bridge->release_data;
+
+	__release_pci_root_info(info);
+}
+
+static int
+probe_pci_root_info(struct pci_root_info *info, struct acpi_device *device,
+		int busnum, int domain)
+{
+	char *name;
+
+	name = kmalloc(16, GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	sprintf(name, "PCI Bus %04x:%02x", domain, busnum);
+	info->bridge = device;
+	info->name = name;
+
+	acpi_walk_resources(device->handle, METHOD_NAME__CRS, count_window,
+			&info->res_num);
+	if (info->res_num) {
+		info->res =
+			kzalloc_node(sizeof(*info->res) * info->res_num,
+				     GFP_KERNEL, info->controller->node);
+		if (!info->res) {
+			kfree(name);
+			return -ENOMEM;
+		}
+
+		info->res_offset =
+			kzalloc_node(sizeof(*info->res_offset) * info->res_num,
+					GFP_KERNEL, info->controller->node);
+		if (!info->res_offset) {
+			kfree(name);
+			kfree(info->res);
+			info->res = NULL;
+			return -ENOMEM;
+		}
+
+		info->res_num = 0;
+		acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+			add_window, info);
+	} else
+		kfree(name);
+
+	return 0;
+}
+
 /* Root bridge scanning */
 struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
 {
-	/* TODO: Should be revisited when implementing PCI on ACPI */
-	return NULL;
+	struct acpi_device *device = root->device;
+	int domain = root->segment;
+	int bus = root->secondary.start;
+	struct pci_controller *controller;
+	struct pci_root_info *info = NULL;
+	int busnum = root->secondary.start;
+	struct pci_bus *pbus;
+	int ret;
+
+	controller = alloc_pci_controller(domain);
+	if (!controller)
+		return NULL;
+
+	controller->companion = device;
+	controller->node = acpi_get_node(device->handle);
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info) {
+		dev_err(&device->dev,
+				"pci_bus %04x:%02x: ignored (out of memory)\n",
+				domain, busnum);
+		kfree(controller);
+		return NULL;
+	}
+
+	info->controller = controller;
+	INIT_LIST_HEAD(&info->resources);
+
+	ret = probe_pci_root_info(info, device, busnum, domain);
+	if (ret) {
+		kfree(info->controller);
+		kfree(info);
+		return NULL;
+	}
+	/* insert busn resource at first */
+	pci_add_resource(&info->resources, &root->secondary);
+
+	pbus = pci_create_root_bus(NULL, bus, &pci_root_ops, controller,
+				   &info->resources);
+	if (!pbus) {
+		pci_free_resource_list(&info->resources);
+		__release_pci_root_info(info);
+		return NULL;
+	}
+
+	pci_set_host_bridge_release(to_pci_host_bridge(pbus->bridge),
+			release_pci_root_info, info);
+	pci_scan_child_bus(pbus);
+	return pbus;
 }
-#endif
+#endif /* CONFIG_ACPI */