[ARM] 3021/1: Interrupt 0 bug fix for ixp4xx

Patch from Kenneth Tan

The get_irqnr_and_base subroutine of ixp4xx does not take interrupt 0 condition into account properly. We should not perform "subs" here. The Z flag will be set when interrupt 0 occur, which resulting "movne r1, sp" in the caller routine (irq_handler) not being executed.

When interrupt 0 occur:
o if CONFIG_CPU_IXP46X is not set, "subs" will set the Z flag and return
o if CONFIG_CPU_IXP46X is set, codes in upper interrupt handling will be trigerred. But since this is not supper interrupt, the "cmp" in the upper interrupt handling portion will set the Z flag and return

Signed-off-by: Kenneth Tan <chong.yin.tan@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 5 insertions, 4 deletions

diff --git a/include/asm-arm/arch-ixp4xx/entry-macro.S b/include/asm-arm/arch-ixp4xx/entry-macro.S
index 455da64832de..323b0bc4a39c 100644
--- a/include/asm-arm/arch-ixp4xx/entry-macro.S
+++ b/include/asm-arm/arch-ixp4xx/entry-macro.S
@@ -15,25 +15,26 @@
                 ldr     \irqstat, =(IXP4XX_INTC_BASE_VIRT+IXP4XX_ICIP_OFFSET)
                 ldr     \irqstat, [\irqstat]            @ get interrupts
                 cmp     \irqstat, #0
-                beq     1001f
+                beq     1001f                           @ upper IRQ?
                 clz     \irqnr, \irqstat
                 mov     \base, #31
-                subs    \irqnr, \base, \irqnr
+                sub     \irqnr, \base, \irqnr
+                b       1002f                           @ lower IRQ being
+                                                        @ handled
 
 1001:
                 /*
                  * IXP465 has an upper IRQ status register
                  */
 #if defined(CONFIG_CPU_IXP46X)
-                bne     1002f
                 ldr     \irqstat, =(IXP4XX_INTC_BASE_VIRT+IXP4XX_ICIP2_OFFSET)
                 ldr     \irqstat, [\irqstat]            @ get upper interrupts
                 mov     \irqnr, #63
                 clz     \irqstat, \irqstat
                 cmp     \irqstat, #32
                 subne   \irqnr, \irqnr, \irqstat
-1002:
 #endif
+1002:
                 .endm