Re: [PATCH V3 18/21] ACPI, PCI: Refine the way to handle translation_offset for ACPI resources

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

Gerry, Tomasz,

On Wed, Jan 13, 2016 at 02:21:04PM +0100, Tomasz Nowicki wrote:
> From: Liu Jiang <jiang.liu@linux.intel.com>
> 
> Some architectures, such as IA64 and ARM64, have no instructions to
> directly access PCI IO ports, so they map PCI IO ports into PCI MMIO
> address space. Typically PCI host bridges on those architectures take
> the responsibility to map (translate) PCI IO port transactions into
> Memory-Mapped IO transactions. ACPI specification provides support
> of such a usage case by using resource translation_offset.
> 
> But current ACPI resource parsing interface isn't neutral enough,
> it still has some special logic for IA64. So refine the ACPI resource
> parsing interface and IA64 code to neutrally handle translation_offset
> by:
> 1) ACPI resource parsing interface doesn't do any translation, it just
>    save the translation_offset to be used by arch code.
> 2) Arch code will do the mapping(translation) based on arch specific
>    information. Typically it does:
> 2.a) Translate per PCI domain IO port address space into system global
>    IO port address space.
> 2.b) Setup MMIO address mapping for IO ports.
> void handle_io_resource(struct resource_entry *io_entry)
> {
> 	struct resource *mmio_res;
> 
> 	mmio_res = kzalloc(sizeof(*mmio_res), GFP_KERNEL);
> 	mmio_res->flags = IORESOURCE_MEM;
> 	mmio_res->start = io_entry->offset + io_entry->res->start;
> 	mmio_res->end = io_entry->offset + io_entry->res->end;
> 	insert_resource(&iomem_resource, mmio_res)
> 
> 	base = map_to_system_ioport_address(entry);
> 	io_entry->offset = base;
> 	io_entry->res->start += base;
> 	io_entry->res->end += base;
> }
> 
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> ---
>  arch/ia64/pci/pci.c     | 26 ++++++++++++++++----------
>  drivers/acpi/resource.c | 12 +++++-------
>  2 files changed, 21 insertions(+), 17 deletions(-)

I still do not understand what TranslationType argument means in the
ACPI specifications Resource descriptors (if you do not check it in
generic code that info is not propagated to arches through the resources
so basically we ignore it - I do not think we can do anything else given
that on ia64 it is missing from ACPI tables), but this patch makes sense
to me (it needs testing/reviewing for ia64 though):

Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

> diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
> index be4c9ef..c75356b 100644
> --- a/arch/ia64/pci/pci.c
> +++ b/arch/ia64/pci/pci.c
> @@ -154,7 +154,7 @@ static int add_io_space(struct device *dev, struct pci_root_info *info,
>  	struct resource_entry *iospace;
>  	struct resource *resource, *res = entry->res;
>  	char *name;
> -	unsigned long base, min, max, base_port;
> +	unsigned long base_mmio, base_port;
>  	unsigned int sparse = 0, space_nr, len;
>  
>  	len = strlen(info->common.name) + 32;
> @@ -172,12 +172,10 @@ static int add_io_space(struct device *dev, struct pci_root_info *info,
>  		goto free_resource;
>  
>  	name = (char *)(iospace + 1);
> -	min = res->start - entry->offset;
> -	max = res->end - entry->offset;
> -	base = __pa(io_space[space_nr].mmio_base);
> +	base_mmio = __pa(io_space[space_nr].mmio_base);
>  	base_port = IO_SPACE_BASE(space_nr);
>  	snprintf(name, len, "%s I/O Ports %08lx-%08lx", info->common.name,
> -		 base_port + min, base_port + max);
> +		 base_port + res->start, base_port + res->end);
>  
>  	/*
>  	 * The SDM guarantees the legacy 0-64K space is sparse, but if the
> @@ -190,19 +188,27 @@ static int add_io_space(struct device *dev, struct pci_root_info *info,
>  	resource = iospace->res;
>  	resource->name  = name;
>  	resource->flags = IORESOURCE_MEM;
> -	resource->start = base + (sparse ? IO_SPACE_SPARSE_ENCODING(min) : min);
> -	resource->end   = base + (sparse ? IO_SPACE_SPARSE_ENCODING(max) : max);
> +	resource->start = base_mmio;
> +	resource->end = base_mmio;
> +	if (sparse) {
> +		resource->start += IO_SPACE_SPARSE_ENCODING(res->start);
> +		resource->end += IO_SPACE_SPARSE_ENCODING(res->end);
> +	} else {
> +		resource->start += res->start;
> +		resource->end += res->end;
> +	}
>  	if (insert_resource(&iomem_resource, resource)) {
>  		dev_err(dev,
>  			"can't allocate host bridge io space resource  %pR\n",
>  			resource);
>  		goto free_resource;
>  	}
> +	resource_list_add_tail(iospace, &info->io_resources);
>  
> +	/* Adjust base of original IO port resource descriptor */
>  	entry->offset = base_port;
> -	res->start = min + base_port;
> -	res->end = max + base_port;
> -	resource_list_add_tail(iospace, &info->io_resources);
> +	res->start += base_port;
> +	res->end += base_port;
>  
>  	return 0;
>  
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index cdc5c25..6578f68 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -190,8 +190,7 @@ static bool acpi_decode_space(struct resource_win *win,
>  {
>  	u8 iodec = attr->granularity == 0xfff ? ACPI_DECODE_10 : ACPI_DECODE_16;
>  	bool wp = addr->info.mem.write_protect;
> -	u64 len = attr->address_length;
> -	u64 start, end, offset = 0;
> +	u64 len = attr->address_length, offset = 0;
>  	struct resource *res = &win->res;
>  
>  	/*
> @@ -215,14 +214,13 @@ static bool acpi_decode_space(struct resource_win *win,
>  	else if (attr->translation_offset)
>  		pr_debug("ACPI: translation_offset(%lld) is invalid for non-bridge device.\n",
>  			 attr->translation_offset);
> -	start = attr->minimum + offset;
> -	end = attr->maximum + offset;
>  
>  	win->offset = offset;
> -	res->start = start;
> -	res->end = end;
> +	res->start = attr->minimum;
> +	res->end = attr->maximum;
>  	if (sizeof(resource_size_t) < sizeof(u64) &&
> -	    (offset != win->offset || start != res->start || end != res->end)) {
> +	    (offset != win->offset || attr->minimum != res->start ||
> +	     attr->maximum != res->end)) {
>  		pr_warn("acpi resource window ([%#llx-%#llx] ignored, not CPU addressable)\n",
>  			attr->minimum, attr->maximum);
>  		return false;
> -- 
> 1.9.1
>