[ARM] 4171/1: i.MX/MX1 optimize interrupt source retrieval

The macro "get_irqnr_and_base" in "entry-macro.S" optimized
according to Lennert Buytenhek suggestion.

Comments from Pavel Pisa:

 Sascha has approved patch some days ago

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 6 insertions, 12 deletions

diff --git a/include/asm-arm/arch-imx/entry-macro.S b/include/asm-arm/arch-imx/entry-macro.S
index 3b9ef6914627..61bb0bdc1b16 100644
--- a/include/asm-arm/arch-imx/entry-macro.S
+++ b/include/asm-arm/arch-imx/entry-macro.S
@@ -13,19 +13,13 @@
                 .endm
 #define AITC_NIVECSR   0x40
                 .macro  get_irqnr_and_base, irqnr, irqstat, base, tmp
-                ldr     \irqstat, =IO_ADDRESS(IMX_AITC_BASE)
+                ldr     \base, =IO_ADDRESS(IMX_AITC_BASE)
                 @ Load offset & priority of the highest priority
                 @ interrupt pending.
-                ldr     \irqnr, [\irqstat, #AITC_NIVECSR]
+                ldr     \irqstat, [\base, #AITC_NIVECSR]
                 @ Shift off the priority leaving the offset or
-                @ "interrupt number"
-                mov     \irqnr, \irqnr, lsr #16
-                ldr     \irqstat, =1    @ dummy compare
-                ldr     \base, =0xFFFF          // invalid interrupt
-                cmp     \irqnr, \base
-                bne     1001f
-                ldr     \irqstat, =0
-1001:
-                tst     \irqstat, #1    @ to make the condition code = TRUE
+                @ "interrupt number", use arithmetic shift to
+                @ transform illegal source (0xffff) as -1
+                mov     \irqnr, \irqstat, asr #16
+                adds    \tmp, \irqnr, #1
                 .endm
-