[PATCH 5.14 179/849] PCI: aardvark: Fix support for PCI_BRIDGE_CTL_BUS_RESET on emulated bridge

Greg Kroah-Hartman
2021-11-15T22:09:51Z

From: Pali Rohár <pali@kernel.org>

commit bc4fac42e5f8460af09c0a7f2f1915be09e20c71 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/pci/controller/pci-aardvark.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -793,6 +793,22 @@ advk_pci_bridge_emul_base_conf_read(stru
*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;
}
@@ -809,6 +825,17 @@ advk_pci_bridge_emul_base_conf_write(str
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;
}