[PATCH 1/2] gpio: gpio-generic: Fix bug in big endian bit conversion

Andreas Larsson andreas at gaisler.com
Tue Feb 5 21:33:02 EST 2013


The swap to convert LE to BE in bgpio_pin2mask_be should be on byte level, not
on bit level.

Signed-off-by: Andreas Larsson <andreas at gaisler.com>
---
 drivers/gpio/gpio-generic.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c
index 05fcc0f..7f11537 100644
--- a/drivers/gpio/gpio-generic.c
+++ b/drivers/gpio/gpio-generic.c
@@ -112,7 +112,10 @@ static unsigned long bgpio_pin2mask(struct bgpio_chip *bgc, unsigned int pin)
 static unsigned long bgpio_pin2mask_be(struct bgpio_chip *bgc,
 				       unsigned int pin)
 {
-	return 1 << (bgc->bits - 1 - pin);
+	unsigned int bit = pin & 0x7; /* Bit number within byte */
+	unsigned int base = pin - bit; /* Pin that is bit 0 within byte */
+
+	return 1 << ((bgc->bits - base - 8) + bit); /* shifted base + bit */
 }
 
 static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
-- 
1.7.0.4



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