[PATCH 1/8] ARM: PCI: remove unused sys->hw

[Russell King - ARM Linux]

On Mon, May 21, 2012 at 04:35:04PM +0200, Thierry Reding wrote:
> I have some patches which convert the Tegra PCIe code to a platform driver. I
> used to use the sys->hw field to obtain a pointer to my driver-private struct
> which had the struct hw_pci embedded.
> 
> Something like this:
> 
> 	struct tegra_pcie_info {
> 		...
> 		struct hw_pci hw;
> 		...
> 	};

The hw_pci struct is not supposed to be embedded into anything - it's
supposed to be a short-term struct used just to initialize things -
it's certainly not required after pci_common_init() returns.

> From ed0421bb87e3fa1484fd54fa504e828e017c3221 Mon Sep 17 00:00:00 2001
> From: Thierry Reding <thierry.reding at avionic-design.de>
> Date: Mon, 21 May 2012 16:25:58 +0200
> Subject: [PATCH] HACK: ARM: PCI: Allow passing driver-private data
> 
> Signed-off-by: Thierry Reding <thierry.reding at avionic-design.de>
> ---
>  arch/arm/include/asm/mach/pci.h |    2 +-
>  arch/arm/kernel/bios32.c        |   16 +++++++++-------
>  2 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
> index 26c511f..5508dc8 100644
> --- a/arch/arm/include/asm/mach/pci.h
> +++ b/arch/arm/include/asm/mach/pci.h
> @@ -52,7 +52,7 @@ struct pci_sys_data {
>  /*
>   * Call this with your hw_pci struct to initialise the PCI system.
>   */
> -void pci_common_init(struct hw_pci *);
> +void pci_common_init(struct hw_pci *, void *);
>  
>  /*
>   * PCI controllers
> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> index 9c0c9a0..45d8171 100644
> --- a/arch/arm/kernel/bios32.c
> +++ b/arch/arm/kernel/bios32.c
> @@ -423,7 +423,8 @@ static int pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
>  	return irq;
>  }
>  
> -static void pcibios_init_hw(struct hw_pci *hw, struct list_head *head)
> +static void pcibios_init_hw(struct hw_pci *hw, struct list_head *head,
> +			    void *private)
>  {
>  	struct pci_sys_data *sys = NULL;
>  	int ret;
> @@ -435,11 +436,12 @@ static void pcibios_init_hw(struct hw_pci *hw, struct list_head *head)
>  			panic("PCI: unable to allocate sys data!");
>  
>  #ifdef CONFIG_PCI_DOMAINS
> -		sys->domain  = hw->domain;
> +		sys->domain       = hw->domain;
>  #endif
> -		sys->busnr   = busnr;
> -		sys->swizzle = hw->swizzle;
> -		sys->map_irq = hw->map_irq;
> +		sys->busnr        = busnr;
> +		sys->swizzle      = hw->swizzle;
> +		sys->map_irq      = hw->map_irq;
> +		sys->private_data = private;

This is inappropriate, because if you look at pcibios_init_hw() you'll
notice that it loops over N buses, and they typically want differing
private data.

If we want to do this, we need to restructure this code.  However...

I'm not sure coupling a platform driver into this code is the best
approach - the platform driver will have to live outside of arch/arm,
yet would depend totally on code within arch/arm.  That sounds like the
wrong approach.  What if some other arch wants to reuse your platform
driver?