irqdomain: Allow quiet failure mode

Some interrupt controllers refuse to map interrupts marked as
"protected" by firwmare. Since we try to map everyting in the
device-tree on some platforms, we end up with a lot of nasty
WARN's in the boot log for what is a normal situation on those
machines.

This defines a specific return code (-EPERM) from the host map()
callback which cause irqdomain to fail silently.

MPIC is updated to return this when hitting a protected source
printing only a single line message for diagnostic purposes.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 11 insertions, 3 deletions

diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index d30e6a676c8..ee21b5e71ae 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1001,8 +1001,12 @@ static int mpic_host_map(struct irq_domain *h, unsigned int virq,
 
 	if (hw == mpic->spurious_vec)
 		return -EINVAL;
-	if (mpic->protected && test_bit(hw, mpic->protected))
-		return -EINVAL;
+	if (mpic->protected && test_bit(hw, mpic->protected)) {
+		pr_warning("mpic: Mapping of source 0x%x failed, "
+			   "source protected by firmware !\n",\
+			   (unsigned int)hw);
+		return -EPERM;
+	}
 
 #ifdef CONFIG_SMP
 	else if (hw >= mpic->ipi_vecs[0]) {
@@ -1029,8 +1033,12 @@ static int mpic_host_map(struct irq_domain *h, unsigned int virq,
 	if (mpic_map_error_int(mpic, virq, hw))
 		return 0;
 
-	if (hw >= mpic->num_sources)
+	if (hw >= mpic->num_sources) {
+		pr_warning("mpic: Mapping of source 0x%x failed, "
+			   "source out of range !\n",\
+			   (unsigned int)hw);
 		return -EINVAL;
+	}
 
 	mpic_msi_reserve_hwirq(mpic, hw);