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    SubjectRe: [RFC PATCH 1/5] PCI: endpoint: Add ops and flag to support internal DMAC
    On Wed, Jan 26, 2022 at 07:50:39PM +0000, Lad Prabhakar wrote:
    > Add flag to indicate if PCIe EP supports internal DMAC and also add a
    > wrapper function which invokes dmac_transfer() callback which lands
    > in the PCIe EP driver.
    >
    > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
    > ---
    > drivers/pci/endpoint/pci-epf-core.c | 32 +++++++++++++++++++++++++++++
    > include/linux/pci-epc.h | 8 ++++++++
    > include/linux/pci-epf.h | 7 +++++++
    > 3 files changed, 47 insertions(+)
    >
    > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
    > index 9ed556936f48..f70576d0d4b2 100644
    > --- a/drivers/pci/endpoint/pci-epf-core.c
    > +++ b/drivers/pci/endpoint/pci-epf-core.c
    > @@ -239,6 +239,38 @@ void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
    > }
    > EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);
    >
    > +/**
    > + * pci_epf_internal_dmac_xfr() - transfer data between EPC and remote PCIe RC

    Transfer data between EP and host using internal DMA engine

    > + * @epf: the EPF device that performs the data transfer operation
    > + * @dma_dst: The destination address of the data transfer. It can be a physical
    > + * address given by pci_epc_mem_alloc_addr or DMA mapping APIs.
    > + * @dma_src: The source address of the data transfer. It can be a physical
    > + * address given by pci_epc_mem_alloc_addr or DMA mapping APIs.
    > + * @len: The size of the data transfer
    > + *
    > + * Invoke to transfer data between EPC and remote PCIe RC using internal dmac.
    > + */
    > +int pci_epf_internal_dmac_xfr(struct pci_epf *epf, dma_addr_t dma_dst,
    > + dma_addr_t dma_src, size_t len,
    > + enum pci_epf_xfr_direction dir)

    How about "pci_epf_internal_dma_xfer"? I think DMAC is somewhat platform
    specific so we could just use DMA. And "xfer" is being used more commonly for
    "transfer".

    > +{
    > + struct pci_epc *epc = epf->epc;
    > + int ret;
    > +
    > + if (IS_ERR_OR_NULL(epc) || IS_ERR_OR_NULL(epf))
    > + return -EINVAL;
    > +
    > + if (!epc->ops->dmac_transfer)
    > + return -EINVAL;
    > +
    > + mutex_lock(&epf->lock);
    > + ret = epc->ops->dmac_transfer(epc, epf, dma_dst, dma_src, len, dir);

    internal_dma_xfer? It doesn't look perfect but I can't think of any other way to
    represent it as an internal dma callback.

    > + mutex_unlock(&epf->lock);
    > +
    > + return ret;
    > +}
    > +EXPORT_SYMBOL_GPL(pci_epf_internal_dmac_xfr);
    > +
    > /**
    > * pci_epf_free_space() - free the allocated PCI EPF register space
    > * @epf: the EPF device from whom to free the memory
    > diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
    > index a48778e1a4ee..b55dacd09e1e 100644
    > --- a/include/linux/pci-epc.h
    > +++ b/include/linux/pci-epc.h
    > @@ -58,6 +58,7 @@ pci_epc_interface_string(enum pci_epc_interface_type type)
    > * @map_msi_irq: ops to map physical address to MSI address and return MSI data
    > * @start: ops to start the PCI link
    > * @stop: ops to stop the PCI link
    > + * @dmac_transfer: ops to transfer data using internal DMAC
    > * @get_features: ops to get the features supported by the EPC
    > * @owner: the module owner containing the ops
    > */
    > @@ -86,6 +87,9 @@ struct pci_epc_ops {
    > u32 *msi_addr_offset);
    > int (*start)(struct pci_epc *epc);
    > void (*stop)(struct pci_epc *epc);
    > + int (*dmac_transfer)(struct pci_epc *epc, struct pci_epf *epf,
    > + dma_addr_t dma_dst, dma_addr_t dma_src,
    > + size_t len, enum pci_epf_xfr_direction dir);
    > const struct pci_epc_features* (*get_features)(struct pci_epc *epc,
    > u8 func_no, u8 vfunc_no);
    > struct module *owner;
    > @@ -159,6 +163,8 @@ struct pci_epc {
    > * for initialization
    > * @msi_capable: indicate if the endpoint function has MSI capability
    > * @msix_capable: indicate if the endpoint function has MSI-X capability
    > + * @internal_dmac: indicate if the endpoint function has internal DMAC
    > + * @internal_dmac_mask: indicates the DMA mask to be applied for the device
    > * @reserved_bar: bitmap to indicate reserved BAR unavailable to function driver
    > * @bar_fixed_64bit: bitmap to indicate fixed 64bit BARs
    > * @bar_fixed_size: Array specifying the size supported by each BAR
    > @@ -169,6 +175,8 @@ struct pci_epc_features {
    > unsigned int core_init_notifier : 1;
    > unsigned int msi_capable : 1;
    > unsigned int msix_capable : 1;
    > + unsigned int internal_dmac : 1;
    > + u64 internal_dmac_mask;

    internal_dma?

    > u8 reserved_bar;
    > u8 bar_fixed_64bit;
    > u64 bar_fixed_size[PCI_STD_NUM_BARS];
    > diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
    > index 009a07147c61..78d661db085d 100644
    > --- a/include/linux/pci-epf.h
    > +++ b/include/linux/pci-epf.h
    > @@ -32,6 +32,11 @@ enum pci_barno {
    > BAR_5,
    > };
    >
    > +enum pci_epf_xfr_direction {
    > + PCIE_TO_INTERNAL,
    > + INTERNAL_TO_PCIE,

    I think we could just use "dma_data_direction" as we are anyway transferring
    data between host and device.

    Thanks,
    Mani

    > +};
    > +
    > /**
    > * struct pci_epf_header - represents standard configuration header
    > * @vendorid: identifies device manufacturer
    > @@ -209,6 +214,8 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar,
    > enum pci_epc_interface_type type);
    > int pci_epf_bind(struct pci_epf *epf);
    > void pci_epf_unbind(struct pci_epf *epf);
    > +int pci_epf_internal_dmac_xfr(struct pci_epf *epf, dma_addr_t dma_dst, dma_addr_t dma_src,
    > + size_t len, enum pci_epf_xfr_direction dir);
    > struct config_group *pci_epf_type_add_cfs(struct pci_epf *epf,
    > struct config_group *group);
    > int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);
    > --
    > 2.25.1
    >

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