sh: lockless gpio_set_value()

This patch optimizes the gpio data register handling for gpio_set_value().

Instead of using the good old spinlock-plus-read-modify-write strategy
we now use a shadow register and atomic operations.

This improves the bitbanging mmc performance on Migo-R from 26 Kbytes/s
to 40 Kbytes/s.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/sh/include/asm/gpio.h b/arch/sh/include/asm/gpio.h
index 942fefa..46a6d79 100644
--- a/arch/sh/include/asm/gpio.h
+++ b/arch/sh/include/asm/gpio.h
@@ -59,7 +59,7 @@ struct pinmux_cfg_reg {
 	.enum_ids = (pinmux_enum_t [(r_width / f_width) * (1 << f_width)]) \
 
 struct pinmux_data_reg {
-	unsigned long reg, reg_width;
+	unsigned long reg, reg_width, reg_shadow;
 	pinmux_enum_t *enum_ids;
 };