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Subject[PATCH 5.15 073/262] PCI: mvebu: Fix support for PCI_EXP_RTSTA on emulated bridge
Date
From: Pali Rohár <pali@kernel.org>

[ Upstream commit 838ff44a398ff47fe9b924961d91aee325821220 ]

PME Status bit in Root Status Register (PCIE_RC_RTSTA_OFF) is read-only and
can be cleared only by writing 0b to the Interrupt Cause RW0C register
(PCIE_INT_CAUSE_OFF).

Link: https://lore.kernel.org/r/20211125124605.25915-15-pali@kernel.org
Fixes: 1f08673eef12 ("PCI: mvebu: Convert to PCI emulated bridge config space")
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pci/controller/pci-mvebu.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index 6100608e6413e..b690768d5a413 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -51,6 +51,8 @@
PCIE_CONF_FUNC(PCI_FUNC(devfn)) | PCIE_CONF_REG(where) | \
PCIE_CONF_ADDR_EN)
#define PCIE_CONF_DATA_OFF 0x18fc
+#define PCIE_INT_CAUSE_OFF 0x1900
+#define PCIE_INT_PM_PME BIT(28)
#define PCIE_MASK_OFF 0x1910
#define PCIE_MASK_ENABLE_INTS 0x0f000000
#define PCIE_CTRL_OFF 0x1a00
@@ -604,7 +606,14 @@ mvebu_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
break;

case PCI_EXP_RTSTA:
- mvebu_writel(port, new, PCIE_RC_RTSTA);
+ /*
+ * PME Status bit in Root Status Register (PCIE_RC_RTSTA)
+ * is read-only and can be cleared only by writing 0b to the
+ * Interrupt Cause RW0C register (PCIE_INT_CAUSE_OFF). So
+ * clear PME via Interrupt Cause.
+ */
+ if (new & PCI_EXP_RTSTA_PME)
+ mvebu_writel(port, ~PCIE_INT_PM_PME, PCIE_INT_CAUSE_OFF);
break;
}
}
--
2.34.1


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