Hi, IIRC I tested that and input and output are independant of each other. If you set a pin as output and write a 1 into the output register, but you connect the pin to ground physically output is "1" and input "0". Which behaviour is the correct one for gpio_get?
Bye, Fabian Am Montag, 7. April 2014, 14:34:52 schrieb Axel Lin: > Read gpio output value from ZEVIO_GPIO_OUTPUT. > The spin_lock is required to ensure the direction is not changed before > reading > input/output value. > > Signed-off-by: Axel Lin <[email protected]> > --- > Hi Fabian, > The document only mentions: > +10 (R/W): Direction (set bit to 0 for output, 1 for input) > +14 (R/W): GPIO output bit > +18 (R): Reads GPIO input bit. > So I'm not sure if reading ZEVIO_GPIO_INPUT returns correct status when the > direction is output. So I think this needs test. > > Regards, > Axel > drivers/gpio/gpio-zevio.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpio/gpio-zevio.c b/drivers/gpio/gpio-zevio.c > index 9bf5034..29b0150 100644 > --- a/drivers/gpio/gpio-zevio.c > +++ b/drivers/gpio/gpio-zevio.c > @@ -81,9 +81,15 @@ static inline void zevio_gpio_port_set(struct zevio_gpio > *c, unsigned pin, > static int zevio_gpio_get(struct gpio_chip *chip, unsigned pin) > { > struct zevio_gpio *controller = to_zevio_gpio(chip); > + u32 val, dir; > > - /* Only reading allowed, so no spinlock needed */ > - u32 val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_INPUT); > + spin_lock(&controller->lock); > + dir = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_DIRECTION); > + if (dir | BIT(ZEVIO_GPIO_BIT(pin))) > + val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_INPUT); > + else > + val = zevio_gpio_port_get(controller, pin, ZEVIO_GPIO_OUTPUT); > + spin_unlock(&controller->lock); > > return (val >> ZEVIO_GPIO_BIT(pin)) & 0x1; > } > -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
