Re: [RFC PATCH 1/2] PCI: generic: remove dependency on hw_pci

[Will Deacon <will.deacon@arm.com>]

Hi Jayachandran,

On Wed, Apr 29, 2015 at 12:39:58PM +0100, Jayachandran C wrote:
> The current code in pci-host-generic.c uses pci_common_init_dev()
> from the arch/arm/ to do a part of the PCI initialization, and this
> prevents it from being used on arm64.
> 
> The initialization done by pci_common_init_dev() that is really
> needed by pci-host-generic.c can be done in the same file without
> using the hw_pci API of ARM.
> 
> The ARM platform requires a pci_sys_data as sysdata for the PCI bus,
> this is be handled by setting up 'struct gen_pci' to embed a
> pci_sys_data variable as the first element on the ARM platform.
> 
> Signed-off-by: Jayachandran C <jchandra@broadcom.com>
> ---
> 
> Notes:
>  - passing a zeroed out pci_sys_data for ARM looks ok, but I haven't
>    tested it on ARM.
>  - tested it on ARM64 fast model
>  - Any information on how this can be tested on arm is welcome.

You should be able to test using a 32-bit guest under KVM.

>  - There is only one ifdef, and that can be removed when arm64 gets
>    a sysdata, or when arm loses its sysdata.

Anyway, I believe Lorenzo (CC'd) has already been working on this so I'll
let him comment here.

Will

> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
> index ba46e58..1631d34 100644
> --- a/drivers/pci/host/pci-host-generic.c
> +++ b/drivers/pci/host/pci-host-generic.c
> @@ -39,6 +39,9 @@ struct gen_pci_cfg_windows {
>  };
>  
>  struct gen_pci {
> +#ifdef CONFIG_ARM
> +	struct pci_sys_data			sys;
> +#endif
>  	struct pci_host_bridge			host;
>  	struct gen_pci_cfg_windows		cfg;
>  	struct list_head			resources;
> @@ -48,8 +51,7 @@ static void __iomem *gen_pci_map_cfg_bus_cam(struct pci_bus *bus,
>  					     unsigned int devfn,
>  					     int where)
>  {
> -	struct pci_sys_data *sys = bus->sysdata;
> -	struct gen_pci *pci = sys->private_data;
> +	struct gen_pci *pci = bus->sysdata;
>  	resource_size_t idx = bus->number - pci->cfg.bus_range->start;
>  
>  	return pci->cfg.win[idx] + ((devfn << 8) | where);
> @@ -64,8 +66,7 @@ static void __iomem *gen_pci_map_cfg_bus_ecam(struct pci_bus *bus,
>  					      unsigned int devfn,
>  					      int where)
>  {
> -	struct pci_sys_data *sys = bus->sysdata;
> -	struct gen_pci *pci = sys->private_data;
> +	struct gen_pci *pci = bus->sysdata;
>  	resource_size_t idx = bus->number - pci->cfg.bus_range->start;
>  
>  	return pci->cfg.win[idx] + ((devfn << 12) | where);
> @@ -198,11 +199,33 @@ static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci)
>  	return 0;
>  }
>  
> -static int gen_pci_setup(int nr, struct pci_sys_data *sys)
> +static int gen_pci_init(struct device *dev, struct gen_pci *pci)
>  {
> -	struct gen_pci *pci = sys->private_data;
> -	list_splice_init(&pci->resources, &sys->resources);
> -	return 1;
> +	struct pci_bus *bus;
> +
> +	pci_add_flags(PCI_REASSIGN_ALL_RSRC);
> +
> +	bus = pci_scan_root_bus(dev, 0, &gen_pci_ops, pci, &pci->resources);
> +	if (!bus) {
> +		dev_err(dev, "Scanning rootbus failed");
> +		return -ENODEV;
> +	}
> +	pci_fixup_irqs(pci_common_swizzle, of_irq_parse_and_map_pci);
> +
> +	if (!pci_has_flag(PCI_PROBE_ONLY)) {
> +		pci_bus_size_bridges(bus);
> +		pci_bus_assign_resources(bus);
> +	}
> +	pci_bus_add_devices(bus);
> +
> +	/* Configure PCI Express settings */
> +	if (pci_has_flag(PCI_PROBE_ONLY)) {
> +		struct pci_bus *child;
> +
> +		list_for_each_entry(child, &bus->children, node)
> +			pcie_bus_configure_settings(child);
> +	}
> +	return 0;
>  }
>  
>  static int gen_pci_probe(struct platform_device *pdev)
> @@ -214,13 +237,6 @@ static int gen_pci_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct device_node *np = dev->of_node;
>  	struct gen_pci *pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
> -	struct hw_pci hw = {
> -		.nr_controllers	= 1,
> -		.private_data	= (void **)&pci,
> -		.setup		= gen_pci_setup,
> -		.map_irq	= of_irq_parse_and_map_pci,
> -		.ops		= &gen_pci_ops,
> -	};
>  
>  	if (!pci)
>  		return -ENOMEM;
> @@ -258,8 +274,7 @@ static int gen_pci_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> -	pci_common_init_dev(dev, &hw);
> -	return 0;
> +	return gen_pci_init(dev, pci);
>  }
>  
>  static struct platform_driver gen_pci_driver = {
> -- 
> 1.9.1
>