From: Liu Gang Date: Fri, 22 Nov 2013 08:12:40 +0000 (+0800) Subject: powerpc/gpio: Fix the wrong GPIO input data on MPC8572/MPC8536 X-Git-Tag: firefly_0821_release~176^2~4832^2~1 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1aeef303b5d9e243c41d5b80f8bb059366514a10;p=firefly-linux-kernel-4.4.55.git powerpc/gpio: Fix the wrong GPIO input data on MPC8572/MPC8536 For MPC8572/MPC8536, the status of GPIOs defined as output cannot be determined by reading GPDAT register, so the code use shadow data register instead. But the code may give the wrong status of GPIOs defined as input under some scenarios: 1. If some pins were configured as inputs and were asserted high before booting the kernel, the shadow data has been initialized with those pin values. 2. Some pins have been configured as output first and have been set to the high value, then reconfigured as input. The above cases will make the shadow data for those input pins to be set to high. Then reading the pin status will always return high even if the actual pin status is low. The code should eliminate the effects of the shadow data to the input pins, and the status of those pins should be read directly from GPDAT. Cc: stable@vger.kernel.org Acked-by: Scott Wood Acked-by: Anatolij Gustschin Signed-off-by: Liu Gang Signed-off-by: Linus Walleij --- diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c index 914e859e3eda..d7d6d72eba33 100644 --- a/drivers/gpio/gpio-mpc8xxx.c +++ b/drivers/gpio/gpio-mpc8xxx.c @@ -70,10 +70,14 @@ static int mpc8572_gpio_get(struct gpio_chip *gc, unsigned int gpio) u32 val; struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc); struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm); + u32 out_mask, out_shadow; - val = in_be32(mm->regs + GPIO_DAT) & ~in_be32(mm->regs + GPIO_DIR); + out_mask = in_be32(mm->regs + GPIO_DIR); - return (val | mpc8xxx_gc->data) & mpc8xxx_gpio2mask(gpio); + val = in_be32(mm->regs + GPIO_DAT) & ~out_mask; + out_shadow = mpc8xxx_gc->data & out_mask; + + return (val | out_shadow) & mpc8xxx_gpio2mask(gpio); } static int mpc8xxx_gpio_get(struct gpio_chip *gc, unsigned int gpio)