Re: [PATCH v3 7/7] PCI: dwc: endpoint: Define the .map_align() controller operation

[Niklas Cassel <cassel@kernel.org>]

On Fri, Oct 04, 2024 at 02:07:42PM +0900, Damien Le Moal wrote:
> The function dw_pcie_prog_outbound_atu() used to program outbound ATU
> entries for mapping RC PCI addresses to local CPU addresses does not
> allow PCI addresses that are not aligned to struct dw_pcie->region_align
> (generally 64K).

I think that you should just remove the "generally 64K". This is totally
dependent on the hardware configuration set when synthesizing the DWC PCIe
controller.

See e.g. drivers/misc/pci_endpoint_test.c:
.alignment = SZ_4K,
.alignment = SZ_64K,
.alignment = 256,

In fact, the most common one, from looking at what the different PCI device
and vendor IDs, seems to be 4k.

Perhaps simply mention that the pci->region_align contains the value that was
read/determined from iATU hardware registers during detection time of the iATU
(done by dw_pcie_iatu_detect()), so this code is actually generic for all DWC
PCIe controllers, and should thus work regardless of the hardware configuration
used when synthesizing the DWC PCIe controller.


> 
> Handle this constraint by defining the endpoint controller .map_align()
> operation to calculate a mapping size and the offset into the mapping
> based on the requested RC PCI address and size to map.
> 
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> ---
>  drivers/pci/controller/dwc/pcie-designware-ep.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 43ba5c6738df..501e527c188e 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -268,6 +268,20 @@ static int dw_pcie_find_index(struct dw_pcie_ep *ep, phys_addr_t addr,
>  	return -EINVAL;
>  }
>  
> +static int dw_pcie_ep_map_align(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> +				struct pci_epc_map *map)
> +{
> +	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
> +	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> +	size_t mask = pci->region_align - 1;
> +
> +	map->map_pci_addr = map->pci_addr & ~mask;
> +	map->map_ofst = map->pci_addr & mask;
> +	map->map_size = ALIGN(map->map_ofst + map->pci_size, ep->page_size);
> +
> +	return 0;
> +}
> +
>  static void dw_pcie_ep_unmap_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
>  				  phys_addr_t addr)
>  {
> @@ -444,6 +458,7 @@ static const struct pci_epc_ops epc_ops = {
>  	.write_header		= dw_pcie_ep_write_header,
>  	.set_bar		= dw_pcie_ep_set_bar,
>  	.clear_bar		= dw_pcie_ep_clear_bar,
> +	.map_align		= dw_pcie_ep_map_align,
>  	.map_addr		= dw_pcie_ep_map_addr,
>  	.unmap_addr		= dw_pcie_ep_unmap_addr,
>  	.set_msi		= dw_pcie_ep_set_msi,
> -- 
> 2.46.2
> 

Reviewed-by: Niklas Cassel <cassel@kernel.org>