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SubjectRe: [RFC 12/14] irq_domain: Add support for base irq and hwirq in legacy mappings
On 01/11/2012 02:22 PM, Grant Likely wrote:
> Add support for a legacy mapping where irq = (hwirq - first_hwirq + first_irq)
> so that a controller driver can allocate a fixed range of irq_descs and use
> a simple calculation to translate back and forth between linux and hw irq
> numbers. This is needed to use an irq_domain with many of the ARM interrupt
> controller drivers that manage their own irq_desc allocations. Ultimately
> the goal is to migrate those drivers to use the linear revmap, but doing it
> this way allows each driver to be converted separately which makes the
> migration path easier.
>
> This patch generalizes the IRQ_DOMAIN_MAP_LEGACY method to use
> (first_irq-first_hwirq) as the offset between hwirq and linux irq number,
> and adds checks to make sure that the hwirq number does not exceed range
> assigned to the controller.
>
> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
> arch/powerpc/include/asm/irq.h | 3 -
> arch/powerpc/sysdev/i8259.c | 2 +-
> arch/powerpc/sysdev/tsi108_pci.c | 2 +-
> include/linux/irqdomain.h | 20 +++++++++-
> kernel/irq/irqdomain.c | 78 +++++++++++++++++++++++++-------------
> 5 files changed, 73 insertions(+), 32 deletions(-)
>

snip...

> @@ -454,8 +477,11 @@ unsigned int irq_find_mapping(struct irq_domain *domain,
> return 0;
>
> /* legacy -> bail early */
> - if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> - return hwirq;
> + if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY) {
> + if (hwirq > domain->revmap_data.legacy.size)
> + return 0;
> + return domain->revmap_data.legacy.first_irq + hwirq;

This needs a "- domain->revmap_data.legacy.first_hwirq"

Rob

> + }
>
> /* Slow path does a linear search of the map */
> if (hint < NUM_ISA_INTERRUPTS)


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