The PSR register works correctly for GPIO pins in input mode, but always returns 0 for GPIO pins in output mode unless the SION bit is set.
The DR register should be used for GPIO pins in output mode to allow correct getting of previously set output value.
Please note that the Linux gpio-mxc driver and the NXP U-Boot mxc_gpio driver already use the DR register for all GPIO pins in output mode:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... https://github.com/nxp-imx/uboot-imx/commit/4afc3f90943c6b117f79b66d2cd04e64...
Signed-off-by: Tomas Paukrt tomaspaukrt@email.cz --- drivers/gpio/mxc_gpio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/gpio/mxc_gpio.c b/drivers/gpio/mxc_gpio.c index cac6b32..28176e1 100644 --- a/drivers/gpio/mxc_gpio.c +++ b/drivers/gpio/mxc_gpio.c @@ -133,7 +133,10 @@ int gpio_get_value(unsigned gpio)
regs = (struct gpio_regs *)gpio_ports[port];
- val = (readl(®s->gpio_psr) >> gpio) & 0x01; + if ((readl(®s->gpio_dir) >> gpio) & 0x01) + val = (readl(®s->gpio_dr) >> gpio) & 0x01; + else + val = (readl(®s->gpio_psr) >> gpio) & 0x01;
return val; } @@ -210,7 +213,10 @@ static void mxc_gpio_bank_set_value(struct gpio_regs *regs, int offset,
static int mxc_gpio_bank_get_value(struct gpio_regs *regs, int offset) { - return (readl(®s->gpio_psr) >> offset) & 0x01; + if ((readl(®s->gpio_dir) >> offset) & 0x01) + return (readl(®s->gpio_dr) >> offset) & 0x01; + else + return (readl(®s->gpio_psr) >> offset) & 0x01; }
/* set GPIO pin 'gpio' as an input */