On Thu, Sep 17, 2015 at 11:41:34PM +0100, David Daney wrote:
> From: David Daney <david.daney@xxxxxxxxxx>
>
> The config space for external PCIe root complexes on some Cavium
> ThunderX SoCs is very similar to CAM and ECAM, but differs in the
> shift values that have to be applied to the bus and devfn numbers to
> compose that address window offset. These root complexes also have
> the interesting property that there is no root bridge, so the standard
> manner of limiting scanning to only the first device doesn't work. We
> can use the standard pci-host-generic driver if we make a minor
> addition to handle these differences, so we...
>
> Add a mapping function for ThunderX PCIe root complexes with a bus
> shift of 24 and devfn shift of 16. Ignore accesses for devices other
> than the first device on the primary bus.
>
> Document the whole thing in devicetree/bindings/pci/host-generic-pci.txt
>
> Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> ---
> .../devicetree/bindings/pci/host-generic-pci.txt | 8 +++---
> drivers/pci/host/pci-host-generic.c | 29 ++++++++++++++++++++++
> 2 files changed, 34 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/pci/host-generic-pci.txt b/Documentation/devicetree/bindings/pci/host-generic-pci.txt
> index 105a968..a5aed0f 100644
> --- a/Documentation/devicetree/bindings/pci/host-generic-pci.txt
> +++ b/Documentation/devicetree/bindings/pci/host-generic-pci.txt
> @@ -14,9 +14,11 @@ tree bindings communicated in pci.txt:
>
> Properties of the host controller node:
>
> -- compatible : Must be "pci-host-cam-generic" or "pci-host-ecam-generic"
> - depending on the layout of configuration space (CAM vs
> - ECAM respectively).
> +- compatible : One of the following with bus:devfn:reg mapped to the
> + PCI config space address window in the bit positions shown:
> + "pci-host-cam-generic" -- 'CAM' bits 16:8:0
> + "pci-host-ecam-generic" -- 'ECAM' bits 20:12:0
> + "cavium,pci-host-thunder-pem" -- bits 24:16:0
To me that's ECAM left shifted by 4. Is not it just a matter of defining
config space base address (ie reg property) differently ?
Lorenzo
>
> - device_type : Must be "pci".
>
> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
> index e364232..e1d8d5b 100644
> --- a/drivers/pci/host/pci-host-generic.c
> +++ b/drivers/pci/host/pci-host-generic.c
> @@ -91,6 +91,32 @@ static struct gen_pci_cfg_bus_ops gen_pci_cfg_ecam_bus_ops = {
> }
> };
>
> +static void __iomem *gen_pci_map_cfg_bus_thunder_pem(struct pci_bus *bus,
> + unsigned int devfn,
> + int where)
> +{
> + struct gen_pci *pci = bus->sysdata;
> + resource_size_t idx = bus->number - pci->cfg.bus_range->start;
> +
> + /*
> + * Thunder PEM is a PCIe RC, but without a root bridge. On
> + * the primary bus, ignore accesses for devices other than
> + * the first device.
> + */
> + if (idx == 0 && (devfn & ~7u))
> + return NULL;
> + return pci->cfg.win[idx] + ((devfn << 16) | where);
> +}
> +
> +static struct gen_pci_cfg_bus_ops gen_pci_cfg_thunder_pem_bus_ops = {
> + .bus_shift = 24,
> + .ops = {
> + .map_bus = gen_pci_map_cfg_bus_thunder_pem,
> + .read = pci_generic_config_read,
> + .write = pci_generic_config_write,
> + }
> +};
> +
> static const struct of_device_id gen_pci_of_match[] = {
> { .compatible = "pci-host-cam-generic",
> .data = &gen_pci_cfg_cam_bus_ops },
> @@ -98,6 +124,9 @@ static const struct of_device_id gen_pci_of_match[] = {
> { .compatible = "pci-host-ecam-generic",
> .data = &gen_pci_cfg_ecam_bus_ops },
>
> + { .compatible = "cavium,pci-host-thunder-pem",
> + .data = &gen_pci_cfg_thunder_pem_bus_ops },
> +
> { },
> };
> MODULE_DEVICE_TABLE(of, gen_pci_of_match);
> --
> 1.9.1
>
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