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authorMaciej W. Rozycki <macro@orcam.me.uk>2021-07-20 05:28:04 +0200
committerThomas Gleixner <tglx@linutronix.de>2021-08-10 23:31:43 +0200
commit0e8c6f56fab3af3ef9f78f486e198792d3af0fa1 (patch)
treef522a4fd6eafd813fe6da9b911fed0f127022b6a /arch/x86/pci
parent6b79164f603d14a3ff9c64330c1ca6c05f0b019e (diff)
x86/PCI: Add support for the Intel 82426EX PIRQ router
The Intel 82426EX ISA Bridge (IB), a part of the Intel 82420EX PCIset, implements PCI interrupt steering with a PIRQ router in the form of two PIRQ Route Control registers, available in the PCI configuration space at locations 0x66 and 0x67 for the PIRQ0# and PIRQ1# lines respectively. The semantics is the same as with the PIIX router, however it is not clear if BIOSes use register indices or line numbers as the cookie to identify PCI interrupts in their routing tables and therefore support either scheme. The IB is directly attached to the Intel 82425EX PCI System Controller (PSC) component of the chipset via a dedicated PSC/IB Link interface rather than the host bus or PCI. Therefore it does not itself appear in the PCI configuration space even though it responds to configuration cycles addressing registers it implements. Use 82425EX's identification then for determining the presence of the IB. References: [1] "82420EX PCIset Data Sheet, 82425EX PCI System Controller (PSC) and 82426EX ISA Bridge (IB)", Intel Corporation, Order Number: 290488-004, December 1995, Section 3.3.18 "PIRQ1RC/PIRQ0RC--PIRQ Route Control Registers", p. 61 Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2107200213490.9461@angie.orcam.me.uk
Diffstat (limited to 'arch/x86/pci')
-rw-r--r--arch/x86/pci/irq.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index 187e284f2021..b937c96f9f85 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -444,6 +444,50 @@ static int pirq_piix_set(struct pci_dev *router, struct pci_dev *dev, int pirq,
}
/*
+ * PIRQ routing for the 82426EX ISA Bridge (IB) ASIC used with the
+ * Intel 82420EX PCIset.
+ *
+ * There are only two PIRQ Route Control registers, available in the
+ * combined 82425EX/82426EX PCI configuration space, at 0x66 and 0x67
+ * for the PIRQ0# and PIRQ1# lines respectively. The semantics is
+ * the same as with the PIIX router.
+ *
+ * References:
+ *
+ * "82420EX PCIset Data Sheet, 82425EX PCI System Controller (PSC)
+ * and 82426EX ISA Bridge (IB)", Intel Corporation, Order Number:
+ * 290488-004, December 1995
+ */
+
+#define PCI_I82426EX_PIRQ_ROUTE_CONTROL 0x66u
+
+static int pirq_ib_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
+{
+ int reg;
+ u8 x;
+
+ reg = pirq;
+ if (reg >= 1 && reg <= 2)
+ reg += PCI_I82426EX_PIRQ_ROUTE_CONTROL - 1;
+
+ pci_read_config_byte(router, reg, &x);
+ return (x < 16) ? x : 0;
+}
+
+static int pirq_ib_set(struct pci_dev *router, struct pci_dev *dev, int pirq,
+ int irq)
+{
+ int reg;
+
+ reg = pirq;
+ if (reg >= 1 && reg <= 2)
+ reg += PCI_I82426EX_PIRQ_ROUTE_CONTROL - 1;
+
+ pci_write_config_byte(router, reg, irq);
+ return 1;
+}
+
+/*
* The VIA pirq rules are nibble-based, like ALI,
* but without the ugly irq number munging.
* However, PIRQD is in the upper instead of lower 4 bits.
@@ -805,6 +849,11 @@ static __init int intel_router_probe(struct irq_router *r, struct pci_dev *route
r->get = pirq_piix_get;
r->set = pirq_piix_set;
return 1;
+ case PCI_DEVICE_ID_INTEL_82425:
+ r->name = "PSC/IB";
+ r->get = pirq_ib_get;
+ r->set = pirq_ib_set;
+ return 1;
}
if ((device >= PCI_DEVICE_ID_INTEL_5_3400_SERIES_LPC_MIN &&