Re: [PATCH 2/4] PCI: rcar-pcie: Remove dependency on ARM-specific struct hw_pci

[Bjorn Helgaas]

On Fri, Oct 02, 2015 at 11:25:05AM +0100, Phil Edworthy wrote:
> The R-Car PCIe host controller driver uses pci_common_init_dev(),
> which is ARM-specific and requires the ARM struct hw_pci. The part of
> pci_common_init_dev() that is needed is limited and can be done here
> without using hw_pci.
> 
> Note that the ARM pcibios functions expect the PCI sysdata to be a pointer
> to a struct pci_sys_data. Add a struct pci_sys_data as the first element
> in struct gen_pci so that when we use a gen_pci pointer as sysdata, it is
> also a pointer to a struct pci_sys_data.
> 
> Create and scan the root bus directly without using the ARM
> pci_common_init_dev() interface.
> 
> This change is based on commit <499733e0cc1a00523c5056a690f65dea7b9da140>
> "PCI: generic: Remove dependency on ARM-specific struct hw_pci".
> 
> Signed-off-by: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
> ---
>  drivers/pci/host/pcie-rcar.c | 76 ++++++++++++++++++++++++++++----------------
>  1 file changed, 48 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c
> index 27e2c20..6057e31 100644
> --- a/drivers/pci/host/pcie-rcar.c
> +++ b/drivers/pci/host/pcie-rcar.c
> @@ -124,7 +124,16 @@ static inline struct rcar_msi *to_rcar_msi(struct msi_controller *chip)
>  }
>  
>  /* Structure representing the PCIe interface */
> +/*
> + * ARM pcibios functions expect the ARM struct pci_sys_data as the PCI
> + * sysdata.  Add pci_sys_data as the first element in struct gen_pci so
> + * that when we use a gen_pci pointer as sysdata, it is also a pointer to
> + * a struct pci_sys_data.
> + */
>  struct rcar_pcie {
> +#ifdef CONFIG_ARM
> +	struct pci_sys_data	sys;
> +#endif
>  	struct device		*dev;
>  	void __iomem		*base;
>  	struct resource		res[RCAR_PCI_MAX_RESOURCES];
> @@ -135,11 +144,6 @@ struct rcar_pcie {
>  	struct			rcar_msi msi;
>  };
>  
> -static inline struct rcar_pcie *sys_to_pcie(struct pci_sys_data *sys)
> -{
> -	return sys->private_data;
> -}
> -
>  static void rcar_pci_write_reg(struct rcar_pcie *pcie, unsigned long val,
>  			       unsigned long reg)
>  {
> @@ -258,7 +262,7 @@ static int rcar_pcie_config_access(struct rcar_pcie *pcie,
>  static int rcar_pcie_read_conf(struct pci_bus *bus, unsigned int devfn,
>  			       int where, int size, u32 *val)
>  {
> -	struct rcar_pcie *pcie = sys_to_pcie(bus->sysdata);
> +	struct rcar_pcie *pcie = bus->sysdata;
>  	int ret;
>  
>  	ret = rcar_pcie_config_access(pcie, RCAR_PCI_ACCESS_READ,
> @@ -283,7 +287,7 @@ static int rcar_pcie_read_conf(struct pci_bus *bus, unsigned int devfn,
>  static int rcar_pcie_write_conf(struct pci_bus *bus, unsigned int devfn,
>  				int where, int size, u32 val)
>  {
> -	struct rcar_pcie *pcie = sys_to_pcie(bus->sysdata);
> +	struct rcar_pcie *pcie = bus->sysdata;
>  	int shift, ret;
>  	u32 data;
>  
> @@ -353,9 +357,8 @@ static void rcar_pcie_setup_window(int win, struct rcar_pcie *pcie)
>  	rcar_pci_write_reg(pcie, mask, PCIEPTCTLR(win));
>  }
>  
> -static int rcar_pcie_setup(int nr, struct pci_sys_data *sys)
> +static int rcar_pcie_setup(int nr, struct list_head *resource, struct rcar_pcie *pcie)
>  {
> -	struct rcar_pcie *pcie = sys_to_pcie(sys);
>  	struct resource *res;
>  	int i;
>  
> @@ -375,30 +378,49 @@ static int rcar_pcie_setup(int nr, struct pci_sys_data *sys)
>  			pci_ioremap_io(nr * SZ_64K, io_start);
>  		}
>  
> -		pci_add_resource(&sys->resources, res);
> +		pci_add_resource(resource, res);
>  	}
> -	pci_add_resource(&sys->resources, &pcie->busn);
> +	pci_add_resource(resource, &pcie->busn);
>  
>  	return 1;
>  }
>  
> -static struct hw_pci rcar_pci = {
> -	.setup          = rcar_pcie_setup,
> -	.map_irq        = of_irq_parse_and_map_pci,
> -	.ops            = &rcar_pcie_ops,
> -};
> -
> -static void rcar_pcie_enable(struct rcar_pcie *pcie)
> +static int rcar_pcie_enable(struct rcar_pcie *pcie)
>  {
> -	struct platform_device *pdev = to_platform_device(pcie->dev);
> +	struct pci_bus *bus, *child;
> +	LIST_HEAD(res);
>  
> -	rcar_pci.nr_controllers = 1;
> -	rcar_pci.private_data = (void **)&pcie;
> -#ifdef CONFIG_PCI_MSI
> -	rcar_pci.msi_ctrl = &pcie->msi.chip;
> -#endif
> +	rcar_pcie_setup(1, &res, pcie);
> +
> +	/* Do not reassign resources if probe only */
> +	if (!pci_has_flag(PCI_PROBE_ONLY))
> +		pci_add_flags(PCI_REASSIGN_ALL_RSRC | PCI_REASSIGN_ALL_BUS);
> +
> +	if (IS_ENABLED(CONFIG_PCI_MSI))
> +		bus = pci_scan_root_bus_msi(pcie->dev, pcie->root_bus_nr,
> +				&rcar_pcie_ops, pcie, &res, &pcie->msi.chip);
> +	else
> +		bus = pci_scan_root_bus(pcie->dev, pcie->root_bus_nr,
> +				&rcar_pcie_ops, pcie, &res);
> +
> +	if (!bus) {
> +		dev_err(pcie->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_common_init_dev(&pdev->dev, &rcar_pci);
> +		list_for_each_entry(child, &bus->children, node)
> +			pcie_bus_configure_settings(child);

I see this is exactly the same in 499733e0cc1a ("PCI: generic: Remove
dependency on ARM-specific struct hw_pci").  But it seems like we should do
pcie_bus_configure_settings() (MPS configuration) *always*, even if
PCI_PROBE_ONLY.  I expected PCI_PROBE_ONLY to mean "don't change any BARs"
but I don't think it means we have to preserve *everything*.

> +	}
> +
> +	pci_bus_add_devices(bus);
> +
> +	return 0;
>  }
>  
>  static int phy_wait_for_ack(struct rcar_pcie *pcie)
> @@ -971,9 +993,7 @@ static int rcar_pcie_probe(struct platform_device *pdev)
>  	data = rcar_pci_read_reg(pcie, MACSR);
>  	dev_info(&pdev->dev, "PCIe x%d: link up\n", (data >> 20) & 0x3f);
>  
> -	rcar_pcie_enable(pcie);
> -
> -	return 0;
> +	return rcar_pcie_enable(pcie);
>  }
>  
>  static struct platform_driver rcar_pcie_driver = {
> -- 
> 1.9.1
> 
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