Re: [Patch v5 1/6] ACPI/PCI: Enhance ACPI core to support sparse IO space

From: Bjorn Helgaas <bhelgaas@google.com>
To: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Hanjun Guo <hanjun.guo@linaro.org>,
	Liviu Dudau <Liviu.Dudau@arm.com>,
	Yijing Wang <wangyijing@huawei.com>, Len Brown <lenb@kernel.org>,
	Vivek Goyal <vgoyal@redhat.com>,
	Thierry Reding <treding@nvidia.com>,
	Jakub Sitnicki <jsitnicki@gmail.com>,
	Lv Zheng <lv.zheng@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org,
	"x86 @ kernel . org" <x86@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [Patch v5 1/6] ACPI/PCI: Enhance ACPI core to support sparse IO space
Date: Wed, 29 Jul 2015 15:37:41 -0500	[thread overview]
Message-ID: <20150729203741.GC9640@google.com> (raw)
In-Reply-To: <1433780448-18636-2-git-send-email-jiang.liu@linux.intel.com>

On Tue, Jun 09, 2015 at 12:20:43AM +0800, Jiang Liu wrote:
> Enhance ACPI resource parsing interfaces to support sparse IO space,
> which will be used to share common code between x86 and IA64 later.
> 
> Tested-by: Tony Luck <tony.luck@intel.com>
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
> ---
>  drivers/acpi/resource.c |    9 ++++++---
>  include/linux/ioport.h  |    1 +
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index 8244f013f210..fdcc73dad2c1 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -123,7 +123,7 @@ bool acpi_dev_resource_memory(struct acpi_resource *ares, struct resource *res)
>  EXPORT_SYMBOL_GPL(acpi_dev_resource_memory);
>  
>  static void acpi_dev_ioresource_flags(struct resource *res, u64 len,
> -				      u8 io_decode)
> +				      u8 io_decode, u8 translation_type)
>  {
>  	res->flags = IORESOURCE_IO;
>  
> @@ -135,6 +135,8 @@ static void acpi_dev_ioresource_flags(struct resource *res, u64 len,
>  
>  	if (io_decode == ACPI_DECODE_16)
>  		res->flags |= IORESOURCE_IO_16BIT_ADDR;
> +	if (translation_type == ACPI_SPARSE_TRANSLATION)
> +		res->flags |= IORESOURCE_IO_SPARSE;
>  }
>  
>  static void acpi_dev_get_ioresource(struct resource *res, u64 start, u64 len,
> @@ -142,7 +144,7 @@ static void acpi_dev_get_ioresource(struct resource *res, u64 start, u64 len,
>  {
>  	res->start = start;
>  	res->end = start + len - 1;
> -	acpi_dev_ioresource_flags(res, len, io_decode);
> +	acpi_dev_ioresource_flags(res, len, io_decode, 0);
>  }
>  
>  /**
> @@ -227,7 +229,8 @@ static bool acpi_decode_space(struct resource_win *win,
>  		acpi_dev_memresource_flags(res, len, wp);
>  		break;
>  	case ACPI_IO_RANGE:
> -		acpi_dev_ioresource_flags(res, len, iodec);
> +		acpi_dev_ioresource_flags(res, len, iodec,
> +					  addr->info.io.translation_type);
>  		break;
>  	case ACPI_BUS_NUMBER_RANGE:
>  		res->flags = IORESOURCE_BUS;
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 388e3ae94f7a..24bea087e7af 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -94,6 +94,7 @@ struct resource {
>  /* PnP I/O specific bits (IORESOURCE_BITS) */
>  #define IORESOURCE_IO_16BIT_ADDR	(1<<0)
>  #define IORESOURCE_IO_FIXED		(1<<1)
> +#define IORESOURCE_IO_SPARSE		(1<<2)

I don't really like this bit.  We adding a new generic IORESOURCE_* bit
just for a special case, and it's only used in one place, for one arch,
during enumeration.

Don't we have a similar problem (struct resource can't express all the
information from an ACPI resource) for the _TRA value for bridge windows?
If it's a similar issue, we should solve it in a similar way.

>  /* PCI ROM control bits (IORESOURCE_BITS) */
>  #define IORESOURCE_ROM_ENABLE		(1<<0)	/* ROM is enabled, same as PCI_ROM_ADDRESS_ENABLE */
> -- 
> 1.7.10.4
> 