[PATCH] powerpc/85xx: Workaround MPC8536 GPIO 1 errata.

[Kumar Gala]

On Aug 11, 2009, at 4:04 AM, Felix Radensky wrote:

> On MPC8536 Rev 1.0 the status of GPIO pins configured
> as output cannot be determined by reading GPDAT register.
> Workaround by reading the status of input pins from GPDAT
> and the status of output pins from a shadow register.
>
> Signed-off-by: Felix Radensky <felix at embedded-sol.com>
> ---
> arch/powerpc/sysdev/mpc8xxx_gpio.c |    6 +++++-
> 1 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/sysdev/mpc8xxx_gpio.c b/arch/powerpc/ 
> sysdev/mpc8xxx_gpio.c
> index 103eace..0b996f3 100644
> --- a/arch/powerpc/sysdev/mpc8xxx_gpio.c
> +++ b/arch/powerpc/sysdev/mpc8xxx_gpio.c
> @@ -56,9 +56,13 @@ static void mpc8xxx_gpio_save_regs(struct  
> of_mm_gpio_chip *mm)
>
> static int mpc8xxx_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);
> +	
> +	val = in_be32(mm->regs + GPIO_DAT) && ~in_be32(mm->regs + GPIO_DIR);

it would be good to add a comment in the code about working around the  
errata.

>
> -	return in_be32(mm->regs + GPIO_DAT) & mpc8xxx_gpio2mask(gpio);
> +	return (val | mpc8xxx_gc->data) & mpc8xxx_gpio2mask(gpio);
> }
>
> static void mpc8xxx_gpio_set(struct gpio_chip *gc, unsigned int  
> gpio, int val)
> -- 
> 1.5.4.3

- k