Hi Kevin,
On Mon, Oct 27, 2014 at 3:29 PM, Kevin Cernekee <cernekee@xxxxxxxxx> wrote:
> On Mon, Oct 27, 2014 at 2:38 PM, Andrew Bresticker
> <abrestic@xxxxxxxxxxxx> wrote:
>> No byte swapping is necessary for accessing the GIC registers.
>>
>> Signed-off-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
>> ---
>> drivers/irqchip/irq-mips-gic.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
>> index 61ac482..7ec3c18 100644
>> --- a/drivers/irqchip/irq-mips-gic.c
>> +++ b/drivers/irqchip/irq-mips-gic.c
>> @@ -37,12 +37,12 @@ static void __gic_irq_dispatch(void);
>>
>> static inline unsigned int gic_read(unsigned int reg)
>> {
>> - return readl(gic_base + reg);
>> + return __raw_readl(gic_base + reg);
>> }
>>
>> static inline void gic_write(unsigned int reg, unsigned int val)
>> {
>> - writel(val, gic_base + reg);
>> + __raw_writel(val, gic_base + reg);
>> }
>
> Hi Andrew,
>
> I just ran into a related problem on bcm3384, a big-endian platform on
> which readl/writel perform extra endian swaps (CONFIG_SWAP_IO_SPACE).
> My solution was twofold:
>
> - Change the irq_reg_{readl,writel} macros so that they can be
> configured to use the __raw_ variants on individual platforms
>
> - Use irq_reg_{readl,writel} instead of directly invoking
> __raw_{readl,writel} in our irqchip driver, so that the irqchip driver
> code always uses the same I/O accessors as the helper functions we're
> using from kernel/irq/generic-chip.c
You could also specify your own irq_reg_{readl,writel} in your
platform's irq.h. Though since it seems like this is pretty common on
MIPS platforms, maybe it makes more sense to have a Kconfig option.
I've added the irqchip maintainers to see what they think.
> Do you think a similar approach might be suitable for the irq-mips-gic driver?
The MIPS GIC driver doesn't use generic irqchip (and I'm not planning
on converting it since it doesn't quite fit in the generic irqchip
model), so I've had it use __raw_{readl,writel} directly.
