x86: Support platform PIRQ routing
On x86 boards, platform chipset receives up to four different
interrupt signals from PCI devices (INTA/B/C/D), which in turn
will be routed to chipset internal PIRQ lines then routed to
8259 PIC finally if configuring the whole system to work under
the so-called PIC mode (in contrast to symmetric IO mode which
uses IOAPIC).
We add two major APIs to aid this, one for routing PIRQ and the
other one for generating a PIRQ routing table.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/pirq_routing.h b/arch/x86/include/asm/pirq_routing.h
new file mode 100644
index 0000000..ddc08e1
--- /dev/null
+++ b/arch/x86/include/asm/pirq_routing.h
@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2015, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * Ported from coreboot src/arch/x86/include/arch/pirq_routing.h
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef _PIRQ_ROUTING_H_
+#define _PIRQ_ROUTING_H_
+
+/*
+ * This is the maximum number on interrupt entries that a PCI device may have.
+ * This is NOT the number of slots or devices in the system
+ * This is NOT the number of entries in the PIRQ table
+ *
+ * This tells us that in the PIRQ table, we are going to have 4 link-bitmap
+ * entries per PCI device which is fixed at 4: INTA, INTB, INTC, and INTD.
+ *
+ * CAUTION: If you change this, PIRQ routing will not work correctly.
+ */
+#define MAX_INTX_ENTRIES 4
+
+#define PIRQ_SIGNATURE \
+ (('$' << 0) + ('P' << 8) + ('I' << 16) + ('R' << 24))
+#define PIRQ_VERSION 0x0100
+
+struct __packed irq_info {
+ u8 bus; /* Bus number */
+ u8 devfn; /* Device and function number */
+ struct __packed {
+ u8 link; /* IRQ line ID, 0=not routed */
+ u16 bitmap; /* Available IRQs */
+ } irq[MAX_INTX_ENTRIES];
+ u8 slot; /* Slot number, 0=onboard */
+ u8 rfu;
+};
+
+struct __packed irq_routing_table {
+ u32 signature; /* PIRQ_SIGNATURE */
+ u16 version; /* PIRQ_VERSION */
+ u16 size; /* Table size in bytes */
+ u8 rtr_bus; /* busno of the interrupt router */
+ u8 rtr_devfn; /* devfn of the interrupt router */
+ u16 exclusive_irqs; /* IRQs devoted exclusively to PCI usage */
+ u16 rtr_vendor; /* Vendor ID of the interrupt router */
+ u16 rtr_device; /* Device ID of the interrupt router */
+ u32 miniport_data;
+ u8 rfu[11];
+ u8 checksum; /* Modulo 256 checksum must give zero */
+ struct irq_info slots[CONFIG_IRQ_SLOT_COUNT];
+};
+
+/**
+ * get_irq_slot_count() - Get the number of entries in the irq_info table
+ *
+ * This calculates the number of entries for the irq_info table.
+ *
+ * @rt: pointer to the base address of the struct irq_info
+ * @return: number of entries
+ */
+static inline int get_irq_slot_count(struct irq_routing_table *rt)
+{
+ return (rt->size - 32) / sizeof(struct irq_info);
+}
+
+/**
+ * pirq_check_irq_routed() - Check whether an IRQ is routed to 8259 PIC
+ *
+ * This function checks whether an IRQ is routed to 8259 PIC for a given link.
+ *
+ * Note: this function should be provided by the platform codes, as the
+ * implementation of interrupt router may be different.
+ *
+ * @link: link number which represents a PIRQ
+ * @irq: the 8259 IRQ number
+ * @return: true if the irq is already routed to 8259 for a given link,
+ * false elsewise
+ */
+bool pirq_check_irq_routed(int link, u8 irq);
+
+/**
+ * pirq_translate_link() - Translate a link value
+ *
+ * This function translates a platform-specific link value to a link number.
+ * On Intel platforms, the link value is normally a offset into the PCI
+ * configuration space into the legacy bridge.
+ *
+ * Note: this function should be provided by the platform codes, as the
+ * implementation of interrupt router may be different.
+ *
+ * @link: platform-specific link value
+ * @return: link number which represents a PIRQ
+ */
+int pirq_translate_link(int link);
+
+/**
+ * pirq_assign_irq() - Assign an IRQ to a PIRQ link
+ *
+ * This function assigns the IRQ to a PIRQ link so that the PIRQ is routed to
+ * the 8259 PIC.
+ *
+ * Note: this function should be provided by the platform codes, as the
+ * implementation of interrupt router may be different.
+ *
+ * @link: link number which represents a PIRQ
+ * @irq: IRQ to which the PIRQ is routed
+ */
+void pirq_assign_irq(int link, u8 irq);
+
+/**
+ * pirq_route_irqs() - Route PIRQs to 8259 PIC
+ *
+ * This function configures all PCI devices' interrupt pins and maps them to
+ * PIRQs and finally 8259 PIC. The routed irq number is written to interrupt
+ * line register in the configuration space of the PCI device for OS to use.
+ * The configuration source is taken from a struct irq_info table, the format
+ * of which is defined in PIRQ routing table spec and PCI BIOS spec.
+ *
+ * @irq: pointer to the base address of the struct irq_info
+ * @num: number of entries in the struct irq_info
+ */
+void pirq_route_irqs(struct irq_info *irq, int num);
+
+/**
+ * copy_pirq_routing_table() - Copy a PIRQ routing table
+ *
+ * This helper function copies the given PIRQ routing table to a given address.
+ * Before copying, it does several sanity tests against the PIRQ routing table.
+ * It also fixes up the table checksum and align the given address to a 16 byte
+ * boundary to meet the PIRQ routing table spec requirements.
+ *
+ * @addr: address to store the copied PIRQ routing table
+ * @rt: pointer to the PIRQ routing table to copy from
+ * @return: end address of the copied PIRQ routing table
+ */
+u32 copy_pirq_routing_table(u32 addr, struct irq_routing_table *rt);
+
+#endif /* _PIRQ_ROUTING_H_ */