4 files changed, 402 insertions, 0 deletions
diff --git a/src/soc/intel/common/block/include/intelblocks/irq.h b/src/soc/intel/common/block/include/intelblocks/irq.h
new file mode 100644
index 0000000000..1c267052c8
--- /dev/null
+++ b/src/soc/intel/common/block/include/intelblocks/irq.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef SOC_INTEL_COMMON_IRQ_H
+#define SOC_INTEL_COMMON_IRQ_H
+
+#include <southbridge/intel/common/acpi_pirq_gen.h>
+#include <types.h>
+
+#define MAX_FNS		8
+
+#define ANY_PIRQ(x)			[PCI_FUNC(x)] = { .fixed_int_pin = PCI_INT_NONE,\
+							  .fixed_pirq = PIRQ_INVALID,	\
+							  .irq_route = IRQ_PIRQ, }
+#define DIRECT_IRQ(x)			[PCI_FUNC(x)] = { .fixed_int_pin = PCI_INT_NONE,\
+							  .fixed_pirq = PIRQ_INVALID,	\
+							  .irq_route = IRQ_DIRECT,}
+#define FIXED_INT_ANY_PIRQ(x, pin)	[PCI_FUNC(x)] = { .fixed_int_pin = pin,		\
+							  .fixed_pirq = PIRQ_INVALID,	\
+							  .irq_route = IRQ_PIRQ,}
+#define FIXED_INT_PIRQ(x, pin, pirq)	[PCI_FUNC(x)] = { .fixed_int_pin = pin,		\
+							  .fixed_pirq = pirq,		\
+							  .irq_route = IRQ_PIRQ,}
+
+struct slot_irq_constraints {
+	unsigned int slot;
+	struct {
+		enum pci_pin fixed_int_pin;
+		enum pirq fixed_pirq;
+		enum {
+			IRQ_NONE = 0,	/* Empty function */
+			IRQ_PIRQ = 1,	/* PIRQ routing, i.e. IRQs 16 - 23 */
+			IRQ_DIRECT = 2,	/* No PIRQ routing, i.e., IRQs > 23 */
+		} irq_route;
+	} fns[MAX_FNS];
+};
+
+struct pci_irq_entry {
+	unsigned int devfn;
+	enum pci_pin pin;
+	unsigned int irq;
+	struct pci_irq_entry *next;
+};
+
+const struct pci_irq_entry *assign_pci_irqs(const struct slot_irq_constraints *constraints,
+					    size_t num_slots);
+
+#endif /* SOC_INTEL_COMMON_IRQ_H */
diff --git a/src/soc/intel/common/block/irq/Kconfig b/src/soc/intel/common/block/irq/Kconfig
new file mode 100644
index 0000000000..d4d9ab1b03
--- /dev/null
+++ b/src/soc/intel/common/block/irq/Kconfig
@@ -0,0 +1,9 @@
+config SOC_INTEL_COMMON_BLOCK_IRQ
+	bool
+	select SOC_INTEL_COMMON_BLOCK_GPIO
+	help
+	  Intel common block support for assigning PCI IRQs dynamically. This
+	  allows coreboot to control the IRQ assignments. They are passed to the
+	  FSP via UPD, and also exposed to the OS in ACPI tables. The SoC must
+	  provide a list of IRQ programming constraints; this module will avoid
+	  IRQs that are used by GPIOs routed to IOAPIC.
diff --git a/src/soc/intel/common/block/irq/Makefile.inc b/src/soc/intel/common/block/irq/Makefile.inc
new file mode 100644
index 0000000000..71b069105c
--- /dev/null
+++ b/src/soc/intel/common/block/irq/Makefile.inc
@@ -0,0 +1 @@
+ramstage-$(CONFIG_SOC_INTEL_COMMON_BLOCK_IRQ) += irq.c
diff --git a/src/soc/intel/common/block/irq/irq.c b/src/soc/intel/common/block/irq/irq.c
new file mode 100644
index 0000000000..0a62bb58c9
--- /dev/null
+++ b/src/soc/intel/common/block/irq/irq.c
@@ -0,0 +1,345 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <assert.h>
+#include <console/console.h>
+#include <device/pci.h>
+#include <device/pci_def.h>
+#include <intelblocks/gpio.h>
+#include <intelblocks/irq.h>
+#include <southbridge/intel/common/acpi_pirq_gen.h>
+#include <stdlib.h>
+#include <string.h>
+#include <types.h>
+
+#define MIN_SHARED_IRQ		16
+#define MAX_SHARED_IRQ		23
+#define TOTAL_SHARED_IRQ	(MAX_SHARED_IRQ - MIN_SHARED_IRQ + 1)
+#define MAX_IRQS		120
+
+#define IDX2PIN(i)		(enum pci_pin)((i) + PCI_INT_A)
+#define PIN2IDX(p)		(size_t)((p) - PCI_INT_A)
+#define INVALID_IRQ		-1
+
+struct pin_info {
+	enum pin_state {
+		FREE_PIN,
+		SHARED_IRQ_PIN,
+		UNIQUE_IRQ_PIN,
+	} pin_state;
+	unsigned int usage_count;
+	unsigned int irq;
+};
+
+static unsigned int irq_share_count[TOTAL_SHARED_IRQ];
+
+/*
+ * Assign PCI IRQs & pins according to controller rules.
+ *
+ * This information is provided to the FSP in order for it to do the
+ * programming; this is required because the FSP is also responsible for
+ * enabling some PCI devices so they will show up on their respective PCI
+ * buses. The FSP & PCH BIOS Specification contain rules for how certain IPs
+ * require their interrupt pin and interrupt line to be programmed.
+ *
+ * IOAPIC IRQs are used for PCI devices & GPIOs. The GPIO IRQs are fixed in
+ * hardware (the IRQ field is RO), and often start at 24, which means
+ * conflicts with PCI devices (if using the default FSP configuration) are very
+ * possible.
+ *
+ * These are the rules:
+ * 1) One entry per slot/function
+ * 2) Functions using PIRQs must use IOxAPIC IRQs 16-23
+ * 3) Single-function devices must use INTA
+ * 4) Each slot must have consistent INTx<->PIRQy mappings
+ * 5) Some functions have special interrupt pin requirements (FIXED_INT_ANY_PIRQ)
+ * 6) PCI Express RPs must be assigned in a special way (FIXED_INT_PIRQ)
+ * 7) Some functions require a unique IRQ number (mostly LPSS devices, DIRECT_IRQ)
+ * 8) PCI functions must avoid sharing an IRQ with a GPIO pad which routes its
+ *    IRQ through IO-APIC.
+ */
+
+static int find_free_unique_irq(void)
+{
+	static unsigned int next_irq = MAX_SHARED_IRQ + 1;
+
+	while (next_irq < MAX_IRQS && gpio_routes_ioapic_irq(next_irq))
+		++next_irq;
+
+	if (next_irq == MAX_IRQS)
+		return INVALID_IRQ;
+
+	return next_irq++;
+}
+
+static enum pci_pin find_free_pin(const struct pin_info pin_info[PCI_INT_MAX])
+{
+	for (size_t pin_idx = 0; pin_idx < PCI_INT_MAX; pin_idx++) {
+		if (pin_info[pin_idx].pin_state == FREE_PIN)
+			return IDX2PIN(pin_idx);
+	}
+
+	return PCI_INT_NONE;
+}
+
+static enum pci_pin find_shareable_pin(const struct pin_info pin_info[PCI_INT_MAX])
+{
+	unsigned int least_shared = 255;
+	int least_index = -1;
+
+	for (size_t pin_idx = 0; pin_idx < PCI_INT_MAX; pin_idx++) {
+		if (pin_info[pin_idx].pin_state == SHARED_IRQ_PIN &&
+		    pin_info[pin_idx].usage_count < least_shared) {
+			least_shared = pin_info[pin_idx].usage_count;
+			least_index = pin_idx;
+		}
+	}
+
+	if (least_index < 0)
+		return PCI_INT_NONE;
+
+	return IDX2PIN(least_index);
+}
+
+static enum pirq find_global_least_used_pirq(void)
+{
+	unsigned int least_shared = 255;
+	int least_index = -1;
+
+	for (size_t i = 0; i < TOTAL_SHARED_IRQ; i++) {
+		if (irq_share_count[i] < least_shared) {
+			least_shared = irq_share_count[i];
+			least_index = i;
+		}
+	}
+
+	if (least_index >= 0)
+		return (enum pirq)least_index + PIRQ_A;
+
+	return PIRQ_INVALID;
+}
+
+
+static int pirq_to_irq(enum pirq pirq)
+{
+	return pirq_idx(pirq) + MIN_SHARED_IRQ;
+}
+
+static bool assign_pirq(struct pin_info pin_info[PCI_INT_MAX], enum pci_pin pin, enum pirq pirq)
+{
+	if (pirq < PIRQ_A || pirq > PIRQ_H) {
+		printk(BIOS_ERR, "ERROR: Invalid pirq constraint %u\n", pirq);
+		return false;
+	}
+
+	const int irq = pirq_to_irq(pirq);
+	pin_info[PIN2IDX(pin)].irq = irq;
+	irq_share_count[pirq_idx(pirq)]++;
+	return true;
+}
+
+static bool assign_pin(enum pci_pin pin, unsigned int fn, enum pin_state state,
+		       struct pin_info *pin_info,
+		       enum pci_pin fn_pin_map[MAX_FNS])
+{
+	if (pin < PCI_INT_A || pin > PCI_INT_D) {
+		printk(BIOS_ERR, "ERROR: Invalid pin constraint %u\n", pin);
+		return false;
+	}
+
+	const size_t pin_idx = PIN2IDX(pin);
+	pin_info[pin_idx].pin_state = state;
+	pin_info[pin_idx].usage_count++;
+	fn_pin_map[fn] = pin;
+
+	return true;
+}
+
+static bool assign_fixed_pins(const struct slot_irq_constraints *constraints,
+			      struct pin_info *pin_info, enum pci_pin fn_pin_map[MAX_FNS])
+{
+	for (size_t i = 0; i < MAX_FNS; i++) {
+		const enum pci_pin fixed_int_pin = constraints->fns[i].fixed_int_pin;
+		if (fixed_int_pin == PCI_INT_NONE)
+			continue;
+
+		if (!assign_pin(fixed_int_pin, i, SHARED_IRQ_PIN, pin_info, fn_pin_map))
+			return false;
+	}
+
+	return true;
+}
+
+static bool assign_fixed_pirqs(const struct slot_irq_constraints *constraints,
+			      struct pin_info *pin_info, enum pci_pin fn_pin_map[MAX_FNS])
+{
+	for (size_t i = 0; i < MAX_FNS; i++) {
+		const enum pirq fixed_pirq = constraints->fns[i].fixed_pirq;
+		if (fixed_pirq == PIRQ_INVALID)
+			continue;
+
+		/* A constraint with a fixed pirq is assumed to also have a
+		   fixed pin */
+		const enum pci_pin pin = fn_pin_map[i];
+		if (pin == PCI_INT_NONE) {
+			printk(BIOS_ERR, "ERROR: Slot %u, pirq %u, no pin for function %lu\n",
+			       constraints->slot, fixed_pirq, i);
+			return false;
+		}
+
+		if (!assign_pirq(pin_info, pin, fixed_pirq))
+			return false;
+	}
+
+	return true;
+}
+
+static bool assign_direct_irqs(const struct slot_irq_constraints *constraints,
+			       struct pin_info *pin_info, enum pci_pin fn_pin_map[MAX_FNS])
+{
+	for (size_t i = 0; i < MAX_FNS; i++) {
+		if (constraints->fns[i].irq_route != IRQ_DIRECT)
+			continue;
+
+		enum pci_pin pin = find_free_pin(pin_info);
+		if (pin == PCI_INT_NONE)
+			return false;
+
+		if (!assign_pin(pin, i, UNIQUE_IRQ_PIN, pin_info, fn_pin_map))
+			return false;
+
+		const int irq = find_free_unique_irq();
+		if (irq == INVALID_IRQ) {
+			printk(BIOS_ERR, "ERROR: No free unique IRQs found\n");
+			return false;
+		}
+
+		const size_t pin_idx = PIN2IDX(pin);
+		pin_info[pin_idx].irq = irq;
+	}
+
+	return true;
+}
+
+static bool assign_shareable_pins(const struct slot_irq_constraints *constraints,
+				  struct pin_info *pin_info, enum pci_pin fn_pin_map[MAX_FNS])
+{
+	for (size_t i = 0; i < MAX_FNS; i++) {
+		if (constraints->fns[i].irq_route != IRQ_PIRQ)
+			continue;
+
+		if (fn_pin_map[i] == PCI_INT_NONE) {
+			enum pci_pin pin = find_free_pin(pin_info);
+			if (pin == PCI_INT_NONE) {
+				pin = find_shareable_pin(pin_info);
+
+				if (pin == PCI_INT_NONE) {
+					printk(BIOS_ERR, "ERROR: No shareable pins found\n");
+					return false;
+				}
+			}
+
+			if (!assign_pin(pin, i, SHARED_IRQ_PIN, pin_info, fn_pin_map))
+				return false;
+		}
+	}
+
+	return true;
+}
+
+static bool assign_pirqs(struct pin_info pin_info[PCI_INT_MAX])
+{
+	for (size_t pin_idx = 0; pin_idx < PCI_INT_MAX; pin_idx++) {
+		if (pin_info[pin_idx].pin_state != SHARED_IRQ_PIN || pin_info[pin_idx].irq != 0)
+			continue;
+
+		enum pirq pirq = find_global_least_used_pirq();
+		if (pirq == PIRQ_INVALID)
+			return false;
+
+		if (!assign_pirq(pin_info, IDX2PIN(pin_idx), pirq))
+			return false;
+	}
+
+	return true;
+}
+
+static void add_entry(struct pci_irq_entry **head, pci_devfn_t devfn, enum pci_pin pin,
+		      unsigned int irq)
+{
+	struct pci_irq_entry *entry = malloc(sizeof(*entry));
+	struct pci_irq_entry **tmp = head;
+
+	entry->devfn = devfn;
+	entry->pin = pin;
+	entry->irq = irq;
+	entry->next = NULL;
+
+	while (*tmp)
+		tmp = &(*tmp)->next;
+
+	*tmp = entry;
+}
+
+static void add_slot_entries(struct pci_irq_entry **head, unsigned int slot,
+			     struct pin_info pin_info[PCI_INT_MAX],
+			     const enum pci_pin fn_pin_map[MAX_FNS])
+{
+	for (size_t fn = 0; fn < MAX_FNS; fn++) {
+		if (fn_pin_map[fn] == PCI_INT_NONE)
+			continue;
+
+		const size_t pin_idx = PIN2IDX(fn_pin_map[fn]);
+		add_entry(head, PCI_DEVFN(slot, fn), fn_pin_map[fn], pin_info[pin_idx].irq);
+	}
+}
+
+static bool assign_slot(struct pci_irq_entry **head,
+			const struct slot_irq_constraints *constraints)
+{
+	struct pin_info pin_info[PCI_INT_MAX] = {0};
+	enum pci_pin fn_pin_map[MAX_FNS] = {0};
+
+	/* The order in which pins are assigned is important in that strict constraints must
+	 * be resolved first. This means fixed_int_pin -> fixed_pirq -> direct route ->
+	 * shared pins -> shared pirqs
+	 */
+	if (!assign_fixed_pins(constraints, pin_info, fn_pin_map))
+		return false;
+
+	if (!assign_fixed_pirqs(constraints, pin_info, fn_pin_map))
+		return false;
+
+	if (!assign_direct_irqs(constraints, pin_info, fn_pin_map))
+		return false;
+
+	if (!assign_shareable_pins(constraints, pin_info, fn_pin_map))
+		return false;
+
+	if (!assign_pirqs(pin_info))
+		return false;
+
+	add_slot_entries(head, constraints->slot, pin_info, fn_pin_map);
+	return true;
+}
+
+const struct pci_irq_entry *assign_pci_irqs(const struct slot_irq_constraints *constraints,
+					    size_t num_slots)
+{
+	struct pci_irq_entry *entries = NULL;
+
+	for (size_t i = 0; i < num_slots; i++) {
+		if (!assign_slot(&entries, &constraints[i]))
+			return NULL;
+	}
+
+	const struct pci_irq_entry *entry = entries;
+	while (entry) {
+		printk(BIOS_INFO, "PCI %2X.%X, %s, using IRQ #%d\n",
+		       PCI_SLOT(entry->devfn), PCI_FUNC(entry->devfn),
+		       pin_to_str(entry->pin), entry->irq);
+
+		entry = entry->next;
+	}
+
+	return entries;
+}