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* [PATCH] ArmPkg/ArmGic: Fix maximum number of interrupts in GICv3
@ 2021-03-09 16:45 Joey Gouly
  2021-05-21 10:49 ` Joey Gouly
  0 siblings, 1 reply; 7+ messages in thread
From: Joey Gouly @ 2021-03-09 16:45 UTC (permalink / raw)
  To: devel; +Cc: joey.gouly, ardb+tianocore, leif, sami.mujawar, andreas.sandberg,
	nd

From: Andreas Sandberg <andreas.sandberg@arm.com>

The GICv3 architecture supports up to 1020 ordinary interrupt
lines. The actual number of interrupts supported is described by the
ITLinesNumber field in the GICD_TYPER register. The total number of
implemented registers is normally calculated as
32*(ITLinesNumber+1). However, maximum value (0x1f) is a special case
since that would indicate that 1024 interrupts are implemented.

Add handling for this special case in ArmGicGetMaxNumInterrupts.

Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
---

The changes can be seen at https://github.com/jgouly/edk2/tree/1396_gic_max_num_intr_v1

 ArmPkg/Drivers/ArmGic/ArmGicLib.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/ArmPkg/Drivers/ArmGic/ArmGicLib.c b/ArmPkg/Drivers/ArmGic/ArmGicLib.c
index 6b01c88206ad8adef3100dd44c0d57660db77783..c4996970eb299776552fe7b54f34fd5a68afff29 100644
--- a/ArmPkg/Drivers/ArmGic/ArmGicLib.c
+++ b/ArmPkg/Drivers/ArmGic/ArmGicLib.c
@@ -1,6 +1,6 @@
 /** @file
 *
-*  Copyright (c) 2011-2018, ARM Limited. All rights reserved.
+*  Copyright (c) 2011-2021, ARM Limited. All rights reserved.
 *
 *  SPDX-License-Identifier: BSD-2-Clause-Patent
 *
@@ -120,7 +120,12 @@ ArmGicGetMaxNumInterrupts (
   IN  INTN          GicDistributorBase
   )
 {
-  return 32 * ((MmioRead32 (GicDistributorBase + ARM_GIC_ICDICTR) & 0x1F) + 1);
+  UINTN ItLines;
+
+  ItLines = MmioRead32 (GicDistributorBase + ARM_GIC_ICDICTR) & 0x1F;
+
+  // Interrupt ID 1020-1023 are reserved;
+  return (ItLines == 0x1f) ? 1020 : 32 * (ItLines + 1);
 }
 
 VOID
-- 
Guid("CE165669-3EF3-493F-B85D-6190EE5B9759")


^ permalink raw reply related	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-05-25 11:55 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-03-09 16:45 [PATCH] ArmPkg/ArmGic: Fix maximum number of interrupts in GICv3 Joey Gouly
2021-05-21 10:49 ` Joey Gouly
2021-05-23  8:55   ` [edk2-devel] " Laszlo Ersek
2021-05-23  9:03     ` Ard Biesheuvel
2021-05-23 11:26       ` Laszlo Ersek
2021-05-24 12:58         ` Sami Mujawar
2021-05-25 11:55           ` Laszlo Ersek

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