[PATCH 5.15 146/917] PCI: aardvark: Fix reporting Data Link Layer Link Active

Greg Kroah-Hartman
2021-11-15T23:32:21Z

From: Pali Rohár <pali@kernel.org>

commit 2b650b7ff20eb7ea8ef9031d20fb657286ab90cc upstream.

Add support for reporting PCI_EXP_LNKSTA_DLLLA bit in Link Control register
on emulated bridge via current LTSSM state. Also correctly indicate DLLLA
capability via PCI_EXP_LNKCAP_DLLLARC bit in Link Control Capability
register.

Link: https://lore.kernel.org/r/20211005180952.6812-14-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>
Reviewed-by: Marek Behún <kabel@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/pci/controller/pci-aardvark.c | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)

--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -321,6 +321,20 @@ static inline bool advk_pcie_link_up(str
return ltssm_state >= LTSSM_L0 && ltssm_state < LTSSM_DISABLED;
}

+static inline bool advk_pcie_link_active(struct advk_pcie *pcie)
+{
+ /*
+ * According to PCIe Base specification 3.0, Table 4-14: Link
+ * Status Mapped to the LTSSM, and 4.2.6.3.6 Configuration.Idle
+ * is Link Up mapped to LTSSM Configuration.Idle, Recovery, L0,
+ * L0s, L1 and L2 states. And according to 3.2.1. Data Link
+ * Control and Management State Machine Rules is DL Up status
+ * reported in DL Active state.
+ */
+ u8 ltssm_state = advk_pcie_ltssm_state(pcie);
+ return ltssm_state >= LTSSM_CONFIG_IDLE && ltssm_state < LTSSM_DISABLED;
+}
+
static inline bool advk_pcie_link_training(struct advk_pcie *pcie)
{
/*
@@ -798,12 +812,26 @@ advk_pci_bridge_emul_pcie_conf_read(stru
return PCI_BRIDGE_EMUL_HANDLED;
}

+ case PCI_EXP_LNKCAP: {
+ u32 val = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg);
+ /*
+ * PCI_EXP_LNKCAP_DLLLARC bit is hardwired in aardvark HW to 0.
+ * But support for PCI_EXP_LNKSTA_DLLLA is emulated via ltssm
+ * state so explicitly enable PCI_EXP_LNKCAP_DLLLARC flag.
+ */
+ val |= PCI_EXP_LNKCAP_DLLLARC;
+ *value = val;
+ return PCI_BRIDGE_EMUL_HANDLED;
+ }
+
case PCI_EXP_LNKCTL: {
/* u32 contains both PCI_EXP_LNKCTL and PCI_EXP_LNKSTA */
u32 val = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg) &
~(PCI_EXP_LNKSTA_LT << 16);
if (advk_pcie_link_training(pcie))
val |= (PCI_EXP_LNKSTA_LT << 16);
+ if (advk_pcie_link_active(pcie))
+ val |= (PCI_EXP_LNKSTA_DLLLA << 16);
*value = val;
return PCI_BRIDGE_EMUL_HANDLED;
}
@@ -811,7 +839,6 @@ advk_pci_bridge_emul_pcie_conf_read(stru
case PCI_CAP_LIST_ID:
case PCI_EXP_DEVCAP:
case PCI_EXP_DEVCTL:
- case PCI_EXP_LNKCAP:
*value = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg);
return PCI_BRIDGE_EMUL_HANDLED;