Messages in this thread | | | Subject | Re: [PATCH V7 04/15] PCI: dwc: Move config space capability search API | From | Vidya Sagar <> | Date | Wed, 22 May 2019 14:26:08 +0530 |
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On 5/22/2019 2:47 AM, Bjorn Helgaas wrote: > On Fri, May 17, 2019 at 06:08:35PM +0530, Vidya Sagar wrote: >> Move PCIe config space capability search API to common DesignWare file >> as this can be used by both host and ep mode codes. >> >> Signed-off-by: Vidya Sagar <vidyas@nvidia.com> >> Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com> >> --- >> Changes since [v6]: >> * Exported dw_pcie_find_capability() API >> >> Changes since [v5]: >> * None >> >> Changes since [v4]: >> * Removed redundant APIs in pcie-designware-ep.c file after moving them >> to pcie-designware.c file based on Bjorn's comments. >> >> Changes since [v3]: >> * Rebased to linux-next top of the tree >> >> Changes since [v2]: >> * None >> >> Changes since [v1]: >> * Removed dw_pcie_find_next_ext_capability() API from here and made a >> separate patch for that >> >> .../pci/controller/dwc/pcie-designware-ep.c | 37 +---------------- >> drivers/pci/controller/dwc/pcie-designware.c | 40 +++++++++++++++++++ >> drivers/pci/controller/dwc/pcie-designware.h | 2 + >> 3 files changed, 44 insertions(+), 35 deletions(-) >> >> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c >> index 2bf5a35c0570..65f479250087 100644 >> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c >> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c >> @@ -40,39 +40,6 @@ void dw_pcie_ep_reset_bar(struct dw_pcie *pci, enum pci_barno bar) >> __dw_pcie_ep_reset_bar(pci, bar, 0); >> } >> >> -static u8 __dw_pcie_ep_find_next_cap(struct dw_pcie *pci, u8 cap_ptr, >> - u8 cap) >> -{ >> - u8 cap_id, next_cap_ptr; >> - u16 reg; >> - >> - if (!cap_ptr) >> - return 0; >> - >> - reg = dw_pcie_readw_dbi(pci, cap_ptr); >> - cap_id = (reg & 0x00ff); >> - >> - if (cap_id > PCI_CAP_ID_MAX) >> - return 0; >> - >> - if (cap_id == cap) >> - return cap_ptr; >> - >> - next_cap_ptr = (reg & 0xff00) >> 8; >> - return __dw_pcie_ep_find_next_cap(pci, next_cap_ptr, cap); >> -} >> - >> -static u8 dw_pcie_ep_find_capability(struct dw_pcie *pci, u8 cap) >> -{ >> - u8 next_cap_ptr; >> - u16 reg; >> - >> - reg = dw_pcie_readw_dbi(pci, PCI_CAPABILITY_LIST); >> - next_cap_ptr = (reg & 0x00ff); >> - >> - return __dw_pcie_ep_find_next_cap(pci, next_cap_ptr, cap); >> -} >> - >> static int dw_pcie_ep_write_header(struct pci_epc *epc, u8 func_no, >> struct pci_epf_header *hdr) >> { >> @@ -612,9 +579,9 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep) >> dev_err(dev, "Failed to reserve memory for MSI/MSI-X\n"); >> return -ENOMEM; >> } >> - ep->msi_cap = dw_pcie_ep_find_capability(pci, PCI_CAP_ID_MSI); >> + ep->msi_cap = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI); >> >> - ep->msix_cap = dw_pcie_ep_find_capability(pci, PCI_CAP_ID_MSIX); >> + ep->msix_cap = dw_pcie_find_capability(pci, PCI_CAP_ID_MSIX); >> >> offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR); >> if (offset) { >> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c >> index 83cdd2ce2486..8f53ce63d17e 100644 >> --- a/drivers/pci/controller/dwc/pcie-designware.c >> +++ b/drivers/pci/controller/dwc/pcie-designware.c >> @@ -14,6 +14,46 @@ >> >> #include "pcie-designware.h" >> >> +/* >> + * These APIs are different from standard pci_find_*capability() APIs in the >> + * sense that former can only be used post device enumeration as they require >> + * 'struct pci_dev *' pointer whereas these APIs require 'struct dw_pcie *' >> + * pointer and can be used before link up also. > > I think this comment is slightly misleading because it suggests the > reason we need these DW interfaces is because we're doing something > before a pci_dev pointer is available. > > But these DW interfaces are used on devices that will *never* have a > pci_dev pointer because they are not PCI devices. They're used on > host controller devices, which have a PCIe link on the downstream > side, but the host controller driver operates them using their > upstream, non-PCI interfaces. Logically, I think they would be > considered parts of Root Complexes, not Root Ports. > > There's actually no reason why that upstream interface should look > anything like PCI; it doesn't need to organize registers into > capability lists at all. It might be convenient for the hardware to > do that and share things with a Root Port device, which *is* a PCI > device, but it's not required. > > It also really has nothing to do with whether the link is up. This > code operates on hardware that is upstream from the link, so we can > reach it regardless of the link. I added this comment after receiving a review comment to justify why standard pci_find_*capability() APIs can't be used here. Hence added this. I understand your comment that DW interface need not have to be a PCI device, but what is present in the hardware is effectively a root port implementation and post enumeration, we get a 'struct pci_dev' created for it, hence I thought it is fine to bring 'struct pci_dev' into picture. Also, I agree that mention of 'link up' is unwarranted and could be reworded in a better way. Do you suggest to remove this comment altogether or reword it s/and can be used before link up also/and can be used before 'struct pci_dev' is available/ ?
> >> + */ >> +static u8 __dw_pcie_find_next_cap(struct dw_pcie *pci, u8 cap_ptr, >> + u8 cap) >> +{ >> + u8 cap_id, next_cap_ptr; >> + u16 reg; >> + >> + if (!cap_ptr) >> + return 0; >> + >> + reg = dw_pcie_readw_dbi(pci, cap_ptr); >> + cap_id = (reg & 0x00ff); >> + >> + if (cap_id > PCI_CAP_ID_MAX) >> + return 0; >> + >> + if (cap_id == cap) >> + return cap_ptr; >> + >> + next_cap_ptr = (reg & 0xff00) >> 8; >> + return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap); >> +} >> + >> +u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap) >> +{ >> + u8 next_cap_ptr; >> + u16 reg; >> + >> + reg = dw_pcie_readw_dbi(pci, PCI_CAPABILITY_LIST); >> + next_cap_ptr = (reg & 0x00ff); >> + >> + return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap); >> +} >> +EXPORT_SYMBOL_GPL(dw_pcie_find_capability); >> + >> int dw_pcie_read(void __iomem *addr, int size, u32 *val) >> { >> if (!IS_ALIGNED((uintptr_t)addr, size)) { >> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h >> index 14762e262758..6cb978132469 100644 >> --- a/drivers/pci/controller/dwc/pcie-designware.h >> +++ b/drivers/pci/controller/dwc/pcie-designware.h >> @@ -251,6 +251,8 @@ struct dw_pcie { >> #define to_dw_pcie_from_ep(endpoint) \ >> container_of((endpoint), struct dw_pcie, ep) >> >> +u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap); >> + >> int dw_pcie_read(void __iomem *addr, int size, u32 *val); >> int dw_pcie_write(void __iomem *addr, int size, u32 val); >> >> -- >> 2.17.1 >>
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