PCI: aardvark: Fix support for PCI_BRIDGE_CTL_BUS_RESET on emulated bridge

Aardvark supports PCIe Hot Reset via PCIE_CORE_CTRL1_REG.

Use it for implementing PCI_BRIDGE_CTL_BUS_RESET bit of PCI_BRIDGE_CONTROL
register on emulated bridge.

With this, the function pci_reset_secondary_bus() starts working and can
reset connected PCIe card. Custom userspace script [1] which uses setpci
can trigger PCIe Hot Reset and reset the card manually.

[1] https://alexforencich.com/wiki/en/pcie/hot-reset-linux

Link: https://lore.kernel.org/r/20211028185659.20329-7-kabel@kernel.org
Fixes: 8a3ebd8de328 ("PCI: aardvark: Implement emulated root PCI bridge config space")
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index ddca454..c3b725a 100644 (file)
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -773,6 +773,22 @@ advk_pci_bridge_emul_base_conf_read(struct pci_bridge_emul *bridge,
                *value = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG);
                return PCI_BRIDGE_EMUL_HANDLED;
 
+       case PCI_INTERRUPT_LINE: {
+               /*
+                * From the whole 32bit register we support reading from HW only
+                * one bit: PCI_BRIDGE_CTL_BUS_RESET.
+                * Other bits are retrieved only from emulated config buffer.
+                */
+               __le32 *cfgspace = (__le32 *)&bridge->conf;
+               u32 val = le32_to_cpu(cfgspace[PCI_INTERRUPT_LINE / 4]);
+               if (advk_readl(pcie, PCIE_CORE_CTRL1_REG) & HOT_RESET_GEN)
+                       val |= PCI_BRIDGE_CTL_BUS_RESET << 16;
+               else
+                       val &= ~(PCI_BRIDGE_CTL_BUS_RESET << 16);
+               *value = val;
+               return PCI_BRIDGE_EMUL_HANDLED;
+       }
+
        default:
                return PCI_BRIDGE_EMUL_NOT_HANDLED;
        }
@@ -789,6 +805,17 @@ advk_pci_bridge_emul_base_conf_write(struct pci_bridge_emul *bridge,
                advk_writel(pcie, new, PCIE_CORE_CMD_STATUS_REG);
                break;
 
+       case PCI_INTERRUPT_LINE:
+               if (mask & (PCI_BRIDGE_CTL_BUS_RESET << 16)) {
+                       u32 val = advk_readl(pcie, PCIE_CORE_CTRL1_REG);
+                       if (new & (PCI_BRIDGE_CTL_BUS_RESET << 16))
+                               val |= HOT_RESET_GEN;
+                       else
+                               val &= ~HOT_RESET_GEN;
+                       advk_writel(pcie, val, PCIE_CORE_CTRL1_REG);
+               }
+               break;
+
        default:
                break;
        }