ACPI, PCI, irq: support IRQ numbers greater than 256

The ACPI compiler uses the extended format when used interrupt numbers are greater than 15. The extended IRQ is 32 bits according to the ACPI spec. The code supports parsing the extended interrupt numbers. However, due to used data structure type; the code silently truncates interrupt numbers greater than 256.

This patch changes the interrupt number type to 32 bits and places an upper limit of 1020 as possible interrupt id. 1020 is the maximum interrupt ID that can be assigned to an ARM SPI interrupt according to ARM architecture.

Signed-off-by Sinan Kaya <[email protected]>

---
 drivers/acpi/pci_link.c | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

drivers/acpi/pci_link.c +1 -0

index 7c8408b..faa37cd 100644
@@ -4,6 +4,7 @@
  *  Copyright (C) 2001, 2002 Andy Grover <[email protected]>
  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
  *  Copyright (C) 2002       Dominik Brodowski <[email protected]>
+ *  Copyright (c) 2015, The Linux Foundation. All rights reserved.
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  *

drivers/acpi/pci_link.c +18 -5

+
+
 static int acpi_pci_link_add(struct acpi_device *device,
 			     const struct acpi_device_id *not_used);
 static void acpi_pci_link_remove(struct acpi_device *device);

@@ -67,12 +76,12 @@ static struct acpi_scan_handler pci_link_handler = {
  * later even the link is disable. Instead, we just repick the active irq
  */
 struct acpi_pci_link_irq {
-	u8 active;		/* Current IRQ */
+	u32 active;		/* Current IRQ */
 	u8 triggering;		/* All IRQs */
 	u8 polarity;		/* All IRQs */
 	u8 resource_type;
 	u8 possible_count;
-	u8 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
+	u32 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
 	u8 initialized:1;
 	u8 reserved:7;
 };

@@ -147,6 +156,13 @@ static acpi_status acpi_pci_link_check_possible(struct acpi_resource *resource,
 					       p->interrupts[i]);
 					continue;
 				}
+				if (p->interrupts[i] >= ACPI_MAX_IRQS) {
+					dev_warn(&link->device->dev,
+						 "Ignoring IRQ(%d) as it exceeds max(%d)\n",
+						 p->interrupts[i],
+						 ACPI_MAX_IRQS - 1);
+					continue;
+				}
 				link->irq.possible[i] = p->interrupts[i];
 				link->irq.possible_count++;
 			}

@@ -279,6 +295,13 @@ static int acpi_pci_link_get_current(struct acpi_pci_link *link)
 		result = -ENODEV;
 	}
 
+	if (irq >= ACPI_MAX_IRQS) {
+		dev_err(&link->device->dev,
+			"Ignoring IRQ(%d) as it exceeds max(%d)\n",
+			irq,  ACPI_MAX_IRQS - 1);
+		result = -ENODEV;
+		goto end;
+	}
 	link->irq.active = irq;
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Link at IRQ %d \n", link->irq.active));

@@ -437,9 +460,6 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
  * enabled system.
  */
 
-#define ACPI_MAX_IRQS		256
-#define ACPI_MAX_ISA_IRQ	16
-
 #define PIRQ_PENALTY_PCI_AVAILABLE	(0)
 #define PIRQ_PENALTY_PCI_POSSIBLE	(16*16)
 #define PIRQ_PENALTY_PCI_USING		(16*16*16)

Signature · 7 lines

Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

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Not sure whether you saw my earlier response about this:

ACPI_MAX_IRQS is only used to size the acpi_irq_penalty[] table (and after your patch, to validate IRQ numbers from ACPI). But I think the acpi_irq_penalty[] table is a design we've outgrown. I *think* we only care about penalties for IRQs 0-15, so even a 256-entry table is more than we need.

If we could make acpi_irq_penalty[] a fixed size of 16 entries or replace it with a linked list, I think we could get rid of ACPI_MAX_IRQS completely. Then the validation checks you add below would be unnecessary and we could handle any interrupt number supplied from ACPI.

I think it would be really nice to get rid of the arbitrary maximum interrupt ID (1020).