[PATCH 3.16 041/306] ARM: pxa: fix GPIO double shifts

Ben Hutchings
2017-02-16T00:00:31Z

From: Robert Jarzmik <robert.jarzmik@free.fr>

commit ca26475bf02ed8562b9b46f91d3e8b52ec312541 upstream.

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>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/arm/mach-pxa/corgi_pm.c | 13 ++++---------
arch/arm/mach-pxa/include/mach/sharpsl_pm.h | 2 +-
arch/arm/mach-pxa/sharpsl_pm.c | 2 +-
arch/arm/mach-pxa/spitz_pm.c | 9 +++------
4 files changed, 9 insertions(+), 17 deletions(-)

--- a/arch/arm/mach-pxa/corgi_pm.c
+++ b/arch/arm/mach-pxa/corgi_pm.c
@@ -131,16 +131,11 @@ static int corgi_should_wakeup(unsigned
return is_resume;
}

-static unsigned long corgi_charger_wakeup(void)
+static bool corgi_charger_wakeup(void)
{
- unsigned long ret;
-
- ret = (!gpio_get_value(CORGI_GPIO_AC_IN) << GPIO_bit(CORGI_GPIO_AC_IN))
- | (!gpio_get_value(CORGI_GPIO_KEY_INT)
- << GPIO_bit(CORGI_GPIO_KEY_INT))
- | (!gpio_get_value(CORGI_GPIO_WAKEUP)
- << GPIO_bit(CORGI_GPIO_WAKEUP));
- return ret;
+ return !gpio_get_value(CORGI_GPIO_AC_IN) ||
+ !gpio_get_value(CORGI_GPIO_KEY_INT) ||
+ !gpio_get_value(CORGI_GPIO_WAKEUP);
}

unsigned long corgipm_read_devdata(int type)
--- a/arch/arm/mach-pxa/sharpsl_pm.c
+++ b/arch/arm/mach-pxa/sharpsl_pm.c
@@ -744,7 +744,7 @@ static int sharpsl_off_charge_battery(vo
time = RCNR;
while (1) {
/* Check if any wakeup event had occurred */
- if (sharpsl_pm.machinfo->charger_wakeup() != 0)
+ if (sharpsl_pm.machinfo->charger_wakeup())
return 0;
/* Check for timeout */
if ((RCNR - time) > SHARPSL_WAIT_CO_TIME)
--- a/arch/arm/mach-pxa/include/mach/sharpsl_pm.h
+++ b/arch/arm/mach-pxa/include/mach/sharpsl_pm.h
@@ -34,7 +34,7 @@ struct sharpsl_charger_machinfo {
#define SHARPSL_STATUS_LOCK 5
#define SHARPSL_STATUS_CHRGFULL 6
#define SHARPSL_STATUS_FATAL 7
- unsigned long (*charger_wakeup)(void);
+ bool (*charger_wakeup)(void);
int (*should_wakeup)(unsigned int resume_on_alarm);
void (*backlight_limit)(int);
int (*backlight_get_status) (void);
--- 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
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)