From 21e77df215e58523a755b5dd006cb17610616f20 Mon Sep 17 00:00:00 2001
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Mon, 1 Sep 2008 22:22:37 +0900
Subject: [PATCH] MIPS: TXx9: Microoptimize interrupt handlers
The IOC interrupt status register on RBTX49XX only have 8 bits. Use
8-bit version of __fls() to optimize interrupt handlers.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---
arch/mips/txx9/rbtx4927/irq.c | 6 +++---
arch/mips/txx9/rbtx4938/irq.c | 8 ++++----
include/asm-mips/txx9/generic.h | 18 ++++++++++++++++++
3 files changed, 25 insertions(+), 7 deletions(-)
diff --git a/arch/mips/txx9/rbtx4927/irq.c b/arch/mips/txx9/rbtx4927/irq.c
index 22076e3f03a8f..9c14ebb26cb4c 100644
--- a/arch/mips/txx9/rbtx4927/irq.c
+++ b/arch/mips/txx9/rbtx4927/irq.c
@@ -133,9 +133,9 @@ static int toshiba_rbtx4927_irq_nested(int sw_irq)
u8 level3;
level3 = readb(rbtx4927_imstat_addr) & 0x1f;
- if (level3)
- sw_irq = RBTX4927_IRQ_IOC + fls(level3) - 1;
- return sw_irq;
+ if (unlikely(!level3))
+ return -1;
+ return RBTX4927_IRQ_IOC + __fls8(level3);
}
static void __init toshiba_rbtx4927_irq_ioc_init(void)
diff --git a/arch/mips/txx9/rbtx4938/irq.c b/arch/mips/txx9/rbtx4938/irq.c
index ca2f8306ce93b..7d21befb8932c 100644
--- a/arch/mips/txx9/rbtx4938/irq.c
+++ b/arch/mips/txx9/rbtx4938/irq.c
@@ -85,10 +85,10 @@ static int toshiba_rbtx4938_irq_nested(int sw_irq)
u8 level3;
level3 = readb(rbtx4938_imstat_addr);
- if (level3)
- /* must use fls so onboard ATA has priority */
- sw_irq = RBTX4938_IRQ_IOC + fls(level3) - 1;
- return sw_irq;
+ if (unlikely(!level3))
+ return -1;
+ /* must use fls so onboard ATA has priority */
+ return RBTX4938_IRQ_IOC + __fls8(level3);
}
static void __init
diff --git a/include/asm-mips/txx9/generic.h b/include/asm-mips/txx9/generic.h
index 1e1a9f2d23796..dc85515eac136 100644
--- a/include/asm-mips/txx9/generic.h
+++ b/include/asm-mips/txx9/generic.h
@@ -64,4 +64,22 @@ struct physmap_flash_data;
void txx9_physmap_flash_init(int no, unsigned long addr, unsigned long size,
const struct physmap_flash_data *pdata);
+/* 8 bit version of __fls(): find first bit set (returns 0..7) */
+static inline unsigned int __fls8(unsigned char x)
+{
+ int r = 7;
+
+ if (!(x & 0xf0)) {
+ r -= 4;
+ x <<= 4;
+ }
+ if (!(x & 0xc0)) {
+ r -= 2;
+ x <<= 2;
+ }
+ if (!(x & 0x80))
+ r -= 1;
+ return r;
+}
+
#endif /* __ASM_TXX9_GENERIC_H */
--
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