ARM: pxa: fix GPIO double shifts

The commit 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of
gpio register") from Oct 17, 2011, leads to the following static checker
warning:
  arch/arm/mach-pxa/spitz_pm.c:172 spitz_charger_wakeup()
  warn: double left shift '!gpio_get_value(SPITZ_GPIO_KEY_INT)
        << (1 << ((SPITZ_GPIO_KEY_INT) & 31))'

As Dan reported, the value is shifted three times :
 - once by gpio_get_value(), which returns either 0 or BIT(gpio)
 - once by the shift operation '<<'
 - a last time by GPIO_bit(gpio) which is BIT(gpio)

Therefore the calculation lead to a chained or operator of :
 - (1 << gpio) << (1 << gpio) = (2^gpio)^gpio = 2 ^ (gpio * gpio)

It is be sheer luck the former statement works, only because each gpio
used is strictly smaller than 6, and therefore 2^(gpio^2) never
overflows a 32 bits value, and because it is used as a boolean value to
check a gpio activation.

As the xxx_charger_wakeup() functions are used as a true/false detection
mechanism, take that opportunity to change their prototypes from integer
return value to boolean one.

Fixes: 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of
gpio register")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>

1 files changed, 3 insertions, 6 deletions

diff --git a/arch/arm/mach-pxa/spitz_pm.c b/arch/arm/mach-pxa/spitz_pm.c
index ea9f9034cb54..4e64a140252e 100644
--- a/arch/arm/mach-pxa/spitz_pm.c
+++ b/arch/arm/mach-pxa/spitz_pm.c
@@ -165,13 +165,10 @@ static int spitz_should_wakeup(unsigned int resume_on_alarm)
 	return is_resume;
 }
 
-static unsigned long spitz_charger_wakeup(void)
+static bool spitz_charger_wakeup(void)
 {
-	unsigned long ret;
-	ret = ((!gpio_get_value(SPITZ_GPIO_KEY_INT)
-		<< GPIO_bit(SPITZ_GPIO_KEY_INT))
-		| gpio_get_value(SPITZ_GPIO_SYNC));
-	return ret;
+	return !gpio_get_value(SPITZ_GPIO_KEY_INT) ||
+		gpio_get_value(SPITZ_GPIO_SYNC);
 }
 
 unsigned long spitzpm_read_devdata(int type)