On Fri, 2 Oct 2015 15:16:49 -0700
Duc Dang <dhd...@apm.com> wrote:
Hi Duc,
> APM X-Gene GICv2m implementation has an erratum where the
> MSI data needs to be the offset from the spi_start in order to
> trigger the correct MSI interrupt. This is different from the
> standard GICv2m implementation where the MSI data is the absolute
> value within the range from spi_start to (spi_start + num_spis)
> of each v2m frame.
>
> This patch reads MSI_IIDR register (present in all GICv2m
> implementations) to identify X-Gene GICv2m implementation and
> apply workaround to change the data portion of MSI vector.
>
> Signed-off-by: Duc Dang <dhd...@apm.com>
> ---
> drivers/irqchip/irq-gic-v2m.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
> index db04fc1..470972c 100644
> --- a/drivers/irqchip/irq-gic-v2m.c
> +++ b/drivers/irqchip/irq-gic-v2m.c
> @@ -43,6 +43,10 @@
>
> #define V2M_MSI_TYPER_NUM_SPI(x) ((x) & V2M_MSI_TYPER_NUM_MASK)
>
> +#define V2M_MSI_IIDR 0xFCC
Please group this with the rest of the registers.
> +/* APM X-Gene with GICv2m MSI_IIDR register value */
> +#define XGENE_GICV2M_MSI_IIDR 0x06000170
> +
Is this value guaranteed to only identify the affected implementation?
Do we have strong guarantees that a fixed implementation will not have
this value?
If not, I'd strongly suggest using a different method (compatible
string).
> struct v2m_data {
> spinlock_t msi_cnt_lock;
> struct resource res; /* GICv2m resource */
> @@ -98,6 +102,16 @@ static void gicv2m_compose_msi_msg(struct irq_data *data,
> struct msi_msg *msg)
> msg->address_hi = (u32) (addr >> 32);
> msg->address_lo = (u32) (addr);
> msg->data = data->hwirq;
> + /*
> + * APM X-Gene GICv2m implementation has an erratum where
> + * the MSI data needs to be the offset from the spi_start
> + * in order to trigger the correct MSI interrupt. This is
> + * different from the standard GICv2m implementation where
> + * the MSI data is the absolute value within the range from
> + * spi_start to (spi_start + num_spis).
> + */
> + if (readl_relaxed(v2m->base + V2M_MSI_IIDR) == XGENE_GICV2M_MSI_IIDR)
> + msg->data = data->hwirq - v2m->spi_start;
> }
>
> static struct irq_chip gicv2m_irq_chip = {
Please add a set of flags to struct v2m_data as well as a flag
(GICV2M_NEEDS_SPI_OFFSET?) that can be checked in the compose method
(we don't needs to read the IIDR register each time we program an MSI):
if (v2m->flags & GICV2M_NEEDS_SPI_OFFSET)
msg->data -= v2m->spi_start;
You can set that flag from the probe function.
Thanks,
M.
--
Jazz is not dead. It just smells funny.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
