linux-kernel - Re: [PATCH 06/20] ARM64 / ACPI: Introduce some PCI functions when PCI is enabled

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Message-Id: <201401171504.24525.arnd@arndb.de>
Date:	Fri, 17 Jan 2014 15:04:23 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Hanjun Guo <hanjun.guo@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	"Russell King - ARM Linux" <linux@....linux.org.uk>,
	linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Grant Likely <grant.likely@...aro.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Olof Johansson <olof@...om.net>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Rob Herring <robh@...nel.org>,
	Mark Rutland <mark.rutland@....com>, patches@...aro.org,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org,
	linaro-acpi@...ts.linaro.org, Charles.Garcia-Tobin@....com
Subject: Re: [PATCH 06/20] ARM64 / ACPI: Introduce some PCI functions when PCI is enabled

On Friday 17 January 2014, Hanjun Guo wrote:
> +++ b/arch/arm64/pci/Makefile
> @@ -0,0 +1 @@
> +obj-y                 += pci.o
> diff --git a/arch/arm64/pci/pci.c b/arch/arm64/pci/pci.c
> new file mode 100644
> index 0000000..4e46790
> --- /dev/null
> +++ b/arch/arm64/pci/pci.c
> @@ -0,0 +1,33 @@
> +#include <linux/acpi.h>
> +#include <linux/types.h>
> +#include <linux/kernel.h>
> +#include <linux/pci.h>
> +
> +/**
> + * raw_pci_read - Platform-specific PCI config space access.
> + *
> + * Default empty implementation.  Replace with an architecture-specific setup
> + * routine, if necessary.
> + */
> +int __weak raw_pci_read(unsigned int domain, unsigned int bus,
> +			unsigned int devfn, int reg, int len, u32 *val)
> +{
> +	return -EINVAL;
> +}
> +
> +int __weak raw_pci_write(unsigned int domain, unsigned int bus,
> +			unsigned int devfn, int reg, int len, u32 val)
> +{
> +	return -EINVAL;
> +}

I'd rather not see __weak functions here. Just provide them unconditionally
so that we can add a proper implementation when needed. You could also
define these as 'static inline' in a header file to keep them from consuming
space in the object code.

> diff --git a/drivers/acpi/plat/arm-core.c b/drivers/acpi/plat/arm-core.c
> index 3c8521d..1835b21 100644
> --- a/drivers/acpi/plat/arm-core.c
> +++ b/drivers/acpi/plat/arm-core.c
> @@ -100,6 +100,25 @@ int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
>  }
>  EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
>  
> +int acpi_isa_irq_to_gsi(unsigned isa_irq, u32 *gsi)
> +{
> +	return -1;
> +}
> +
> +int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base)
> +{
> +	/* TBD */
> +	return -EINVAL;
> +}
> +EXPORT_SYMBOL(acpi_register_ioapic);
> +
> +int acpi_unregister_ioapic(acpi_handle handle, u32 gsi_base)
> +{
> +	/* TBD */
> +	return -EINVAL;
> +}
> +EXPORT_SYMBOL(acpi_unregister_ioapic);
> +

My feeling is that these are better handled in the ACPI code by not
calling them on architectures that have no ISA or no IOAPIC support.

We have configuration symbols for both, so you don't have to make
it depend on CONFIG_ARM64 or CONFIG_X86.

	Arnd
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