Re: [PATCH v1 1/3] ARM64 LPC: indirect ISA PORT IO introduced

From: Arnd Bergmann <arnd@arndb.de>
To: Rongrong Zou <zourongrong@gmail.com>
Cc: catalin.marinas@arm.com, will.deacon@arm.com,
	benh@kernel.crashing.org, lijianhua@huawei.com,
	lixiancai@huawei.com, linuxarm@huawei.com,
	linux-kernel@vger.kernel.org, minyard@acm.org,
	gregkh@linuxfoundation.org
Subject: Re: [PATCH v1 1/3] ARM64 LPC: indirect ISA PORT IO introduced
Date: Tue, 29 Dec 2015 14:47:01 +0100	[thread overview]
Message-ID: <3232651.99Svz5pbDW@wuerfel> (raw)
In-Reply-To: <1451396032-23708-2-git-send-email-zourongrong@gmail.com>

On Tuesday 29 December 2015 21:33:50 Rongrong Zou wrote:
> Indirect ISA port I/O accessing introduced, vendors can hook
> their own in/out function to general inb/outb. Drivers can access
> legacy ISA I/O port by inb/outb as it is done in x86 platform.
> 
> Signed-off-by: Rongrong Zou <zourongrong@gmail.com>

Looks correct to me, but I have a few style comments

> ---
>  arch/arm64/Kconfig.platforms |  5 ++-
>  arch/arm64/include/asm/io.h  | 78 ++++++++++++++++++++++++++++++++++++++++++++
>  arch/arm64/kernel/setup.c    |  5 +++
>  3 files changed, 87 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms
> index 4043c35..98ae206 100644
> --- a/arch/arm64/Kconfig.platforms
> +++ b/arch/arm64/Kconfig.platforms
> @@ -127,5 +127,8 @@ config ARCH_ZYNQMP
>  	bool "Xilinx ZynqMP Family"
>  	help
>  	  This enables support for Xilinx ZynqMP Family
> -
> +config ARM64_INDIRECT_PIO
> +	bool "ARM64 Indirect port I/O"
> +	help
> +	  This enables support for ARM64 indirect port I/O
>  endmenu

The option should probably go into arch/arm64/Kconfig. Possibly you can make
it a silent option that just gets selected whenever a driver is enabled
that might set the callbacks.

> diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
> index 44be1e0..0041f3b 100644
> --- a/arch/arm64/include/asm/io.h
> +++ b/arch/arm64/include/asm/io.h
> @@ -193,6 +193,84 @@ extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size);
>   */
>  #define xlate_dev_kmem_ptr(p)	p
>  
> +#ifdef CONFIG_ARM64_INDIRECT_PIO
> +#define DEF_PCI_HOOK_pio(x)   x
> +#else
> +#define DEF_PCI_HOOK_pio(x)   NULL
> +#endif

Maybe just put the entire definition block inside #ifdef and
fall back to the default inb/outb definitions otherwise.

> +/*
> + * This value is equal to PCIBIOS_MIN_IO
> + */
> +#define LEGACY_ISA_PORT_MAX 0x1000

I would just use PCIBIOS_MIN_IO instead of defining another macro.

> +extern struct arm64_isa_io {
> +	u8 (*inb)(unsigned long port);
> +	u16 (*inw)(unsigned long port);
> +	u32 (*inl)(unsigned long port);
> +	void (*outb)(u8 value, unsigned long port);
> +	void (*outw)(u16 value, unsigned long port);
> +	void (*outl)(u32 value, unsigned long port);
> +} arm64_isa_io;

Maybe make this a single function pointer like

void (*arm64_indirect_pio)(unsigned long port, bool write, int size, void *data);

I'm guessing that this would result in smaller object code at the call sites,
but you'd have to try.

	Arnd