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

Kumar Gala galak at kernel.crashing.org
Tue Aug 11 23:57:55 EST 2009


On Aug 11, 2009, at 8:44 AM, Anton Vorontsov wrote:

> On Tue, Aug 11, 2009 at 12:04:18PM +0300, 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);
>
> Are you sure about &&?
>
> Plus, this are two reads instead of just one. I think it'll be better
> to implement mpc8536_gpio_get(), and then do
>
> if (of_device_is_compatible(np, ... 8536-gpio-bank ...))
> 	gc->get = mpc8536_gpio_get;
> else
> 	gc->get = mpc8xxx_gpio_get;

I think 8572 has the same 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)
>
> Thanks,
>
> -- 
> Anton Vorontsov
> email: cbouatmailru at gmail.com
> irc://irc.freenode.net/bd2
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