Re: [PATCH v2 03/40] PCI: dwc: Allow overriding bridge pci_ops

[Vidya Sagar <vidyas@nvidia.com>]

On 8/21/2020 9:23 AM, Rob Herring wrote:
> In preparation to allow drivers to set their own root and child pci_ops
> instead of using the DWC specific config space ops, we need to make
> the pci_host_bridge pointer available and move setting the bridge->ops
> and bridge->child_ops pointer to before the .host_init() hook.
> 
> Cc: Jingoo Han <jingoohan1@gmail.com>
> Cc: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
>   drivers/pci/controller/dwc/pcie-designware-host.c | 15 ++++++++++-----
>   drivers/pci/controller/dwc/pcie-designware.h      |  1 +
>   2 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 1d98554db009..b626cc7cd43a 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -344,6 +344,8 @@ int dw_pcie_host_init(struct pcie_port *pp)
>   	if (!bridge)
>   		return -ENOMEM;
>   
> +	pp->bridge = bridge;
> +
>   	/* Get the I/O and memory ranges from DT */
>   	resource_list_for_each_entry(win, &bridge->windows) {
>   		switch (resource_type(win->res)) {
> @@ -445,6 +447,10 @@ int dw_pcie_host_init(struct pcie_port *pp)
>   		}
>   	}
>   
> +	/* Set default bus ops */
> +	bridge->ops = &dw_pcie_ops;
> +	bridge->child_ops = &dw_pcie_ops;
> +
>   	if (pp->ops->host_init) {
>   		ret = pp->ops->host_init(pp);
>   		if (ret)
> @@ -452,7 +458,6 @@ int dw_pcie_host_init(struct pcie_port *pp)
>   	}
>   
>   	bridge->sysdata = pp;
> -	bridge->ops = &dw_pcie_ops;
>   
>   	ret = pci_scan_root_bus_bridge(bridge);
>   	if (ret)
> @@ -654,11 +659,11 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
>   	dw_pcie_writel_dbi(pci, PCI_COMMAND, val);
>   
>   	/*
> -	 * If the platform provides ->rd_other_conf, it means the platform
> -	 * uses its own address translation component rather than ATU, so
> -	 * we should not program the ATU here.
> +	 * If the platform provides its own child bus config accesses, it means
> +	 * the platform uses its own address translation component rather than
> +	 * ATU, so we should not program the ATU here.
It is possible that a platform can have its own translation for 
configuration accesses and use DWC's ATU for memory/IO address 
translations. IMHO, ATU setup for memory/IO address translations 
shouldn't be skipped based on platform's '->rd_other_conf' 
implementation. Ex:- A platform can implement configuration space access 
through the ECAM mechanism yet choose to use ATU for memory/IO address 
translations.

Thanks,
Vidya Sagar
>   	 */
> -	if (!pp->ops->rd_other_conf) {
> +	if (pp->bridge->child_ops == &dw_pcie_ops && !pp->ops->rd_other_conf) {
>   		dw_pcie_prog_outbound_atu(pci, PCIE_ATU_REGION_INDEX0,
>   					  PCIE_ATU_TYPE_MEM, pp->mem_base,
>   					  pp->mem_bus_addr, pp->mem_size);
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index f911760dcc69..8b8ea5f3e7af 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -200,6 +200,7 @@ struct pcie_port {
>   	u32			num_vectors;
>   	u32			irq_mask[MAX_MSI_CTRLS];
>   	struct pci_bus		*root_bus;
> +	struct pci_host_bridge  *bridge;
>   	raw_spinlock_t		lock;
>   	DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
>   };
>