From cb004c28dd2fabbb57bc03fb002f780054c28780 Mon Sep 17 00:00:00 2001 From: Arindam Nath Date: Wed, 5 Feb 2020 21:24:18 +0530 Subject: [PATCH] NTB: Fix access to link status and control register The design of AMD NTB implementation is such that NTB primary acts as an endpoint device and NTB secondary is an endpoint device behind a combination of Switch Upstream and Switch Downstream. Considering that, the link status and control register needs to be accessed differently based on the NTB topology. So in the case of NTB secondary, we first get the pointer to the Switch Downstream device for the NTB device. Then we get the pointer to the Switch Upstream device. Once we have that, we read the Link Status and Control register to get the correct status of link at the secondary. In the case of NTB primary, simply reading the Link Status and Control register of the NTB device itself will suffice. Suggested-by: Jiasen Lin Signed-off-by: Arindam Nath Signed-off-by: Jon Mason --- drivers/ntb/hw/amd/ntb_hw_amd.c | 40 ++++++++++++++++++++++++++++++--- 1 file changed, 37 insertions(+), 3 deletions(-) diff --git a/drivers/ntb/hw/amd/ntb_hw_amd.c b/drivers/ntb/hw/amd/ntb_hw_amd.c index ae911053ba9c..9a60f34a37c2 100644 --- a/drivers/ntb/hw/amd/ntb_hw_amd.c +++ b/drivers/ntb/hw/amd/ntb_hw_amd.c @@ -842,6 +842,9 @@ static inline void ndev_init_struct(struct amd_ntb_dev *ndev, static int amd_poll_link(struct amd_ntb_dev *ndev) { void __iomem *mmio = ndev->peer_mmio; + struct pci_dev *pdev = NULL; + struct pci_dev *pci_swds = NULL; + struct pci_dev *pci_swus = NULL; u32 reg, stat; int rc; @@ -855,10 +858,41 @@ static int amd_poll_link(struct amd_ntb_dev *ndev) ndev->cntl_sta = reg; - rc = pcie_capability_read_dword(ndev->ntb.pdev, - PCI_EXP_LNKCTL, &stat); - if (rc) + if (ndev->ntb.topo == NTB_TOPO_SEC) { + /* Locate the pointer to Downstream Switch for this device */ + pci_swds = pci_upstream_bridge(ndev->ntb.pdev); + if (pci_swds) { + /* + * Locate the pointer to Upstream Switch for + * the Downstream Switch. + */ + pci_swus = pci_upstream_bridge(pci_swds); + if (pci_swus) { + rc = pcie_capability_read_dword(pci_swus, + PCI_EXP_LNKCTL, + &stat); + if (rc) + return 0; + } else { + return 0; + } + } else { + return 0; + } + } else if (ndev->ntb.topo == NTB_TOPO_PRI) { + /* + * For NTB primary, we simply read the Link Status and control + * register of the NTB device itself. + */ + pdev = ndev->ntb.pdev; + rc = pcie_capability_read_dword(pdev, PCI_EXP_LNKCTL, &stat); + if (rc) + return 0; + } else { + /* Catch all for everything else */ return 0; + } + ndev->lnk_sta = stat; return 1;