Commit 1cf215a5 authored by Magnus Damm's avatar Magnus Damm Committed by Paul Mundt

ARM: mach-shmobile: INTC interrupt priority level demux fix

Fix interrupt priority level handling on SH-Mobile ARM.

SH-Mobile ARM platforms using multiple interrupt priority
levels need this patch to fix a potential dead lock that
may occur if multiple interrupts with different levels
are pending simultaneously.

The default INTC configuration is to use the same priority
level for all interrupts, so this issue does not trigger by
default. It is however common for board code to override the
interrupt priority for certain interrupt sources depending
on the application. Without this fix such boards may lock up.

In detail, this patch updates the INTC code in entry-macro.S
to make sure that the INTLVLA register gets set as expected.

To trigger this bug modify the board specific code to adjust
the interrupt priority level for the ethernet chip. After
changing the priority level simply use flood ping to drown
the board with interrupts.

This patch applies to INTCA-based processors such as sh7372,
sh7377 and sh7372. GIC-based processors are not affected.

Suitable for v2.6.37-rc and stable from v2.6.34 to v2.6.36.

Cc: stable@kernel.org
Signed-off-by: default avatarMagnus Damm <damm@opensource.se>
Tested-by: default avatarKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 676b14c3
/*
* Copyright (C) 2010 Magnus Damm
* Copyright (C) 2008 Renesas Solutions Corp.
*
* This program is free software; you can redistribute it and/or modify
......@@ -14,24 +15,45 @@
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <mach/hardware.h>
#include <mach/irqs.h>
#define INTCA_BASE 0xe6980000
#define INTFLGA_OFFS 0x00000018 /* accept pending interrupt */
#define INTEVTA_OFFS 0x00000020 /* vector number of accepted interrupt */
#define INTLVLA_OFFS 0x00000030 /* priority level of accepted interrupt */
#define INTLVLB_OFFS 0x00000034 /* previous priority level */
.macro disable_fiq
.endm
.macro get_irqnr_preamble, base, tmp
ldr \base, =INTFLGA
ldr \base, =INTCA_BASE
.endm
.macro arch_ret_to_user, tmp1, tmp2
.endm
.macro get_irqnr_and_base, irqnr, irqstat, base, tmp
ldr \irqnr, [\base]
/* The single INTFLGA read access below results in the following:
*
* 1. INTLVLB is updated with old priority value from INTLVLA
* 2. Highest priority interrupt is accepted
* 3. INTLVLA is updated to contain priority of accepted interrupt
* 4. Accepted interrupt vector is stored in INTFLGA and INTEVTA
*/
ldr \irqnr, [\base, #INTFLGA_OFFS]
/* Restore INTLVLA with the value saved in INTLVLB.
* This is required to support interrupt priorities properly.
*/
ldrb \tmp, [\base, #INTLVLB_OFFS]
strb \tmp, [\base, #INTLVLA_OFFS]
/* Handle invalid vector number case */
cmp \irqnr, #0
beq 1000f
/* intevt to irq number */
/* Convert vector to irq number, same as the evt2irq() macro */
lsr \irqnr, \irqnr, #0x5
subs \irqnr, \irqnr, #16
......
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