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

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Message-Id: <1360060383-16880-2-git-send-email-andreas@gaisler.com>
Date:	Tue,  5 Feb 2013 11:33:02 +0100
From:	Andreas Larsson <andreas@...sler.com>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	software@...sler.com
Subject: [PATCH 1/2] gpio: gpio-generic: Fix bug in big endian bit conversion

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@...sler.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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