[POWERPC] MPIC protected sources

Some HW platforms, such as the new cell blades, requires some MPIC sources
to be left alone by the operating system. This implements support for
a "protected-sources" property in the mpic controller node containing a list
of source numbers to be protected against operating system interference.

For those interested in the gory details, the MPIC on the southbridge of
those blades has some of the processor outputs routed to the cell, and
at least one routed as a GPIO to the service processor. It will be used
in the GA product for routing some of the southbridge error interrupts
to the service processor which implements some of the RAS stuff, such
as checkstopping when fatal errors occurs before they can propagate.

Signed-off-by: Benjamin Herrenschmidt <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/sysdev/mpic.c

···
 
 	if (hw == mpic->spurious_vec)
 		return -EINVAL;
+	if (mpic->protected && test_bit(hw, mpic->protected))
+		return -EINVAL;
 
 #ifdef CONFIG_SMP
 	else if (hw >= mpic->ipi_vecs[0]) {
···
 	if (node && of_get_property(node, "big-endian", NULL) != NULL)
 		mpic->flags |= MPIC_BIG_ENDIAN;
 
+	/* Look for protected sources */
+	if (node) {
+		unsigned int psize, bits, mapsize;
+		const u32 *psrc =
+			of_get_property(node, "protected-sources", &psize);
+		if (psrc) {
+			psize /= 4;
+			bits = intvec_top + 1;
+			mapsize = BITS_TO_LONGS(bits) * sizeof(unsigned long);
+			mpic->protected = alloc_bootmem(mapsize);
+			BUG_ON(mpic->protected == NULL);
+			memset(mpic->protected, 0, mapsize);
+			for (i = 0; i < psize; i++) {
+				if (psrc[i] > intvec_top)
+					continue;
+				__set_bit(psrc[i], mpic->protected);
+			}
+		}
+	}
 
 #ifdef CONFIG_MPIC_WEIRD
 	mpic->hw_set = mpic_infos[MPIC_GET_REGSET(flags)];
···
 		u32 vecpri = MPIC_VECPRI_MASK | i |
 			(8 << MPIC_VECPRI_PRIORITY_SHIFT);
 		
+		/* check if protected */
+		if (mpic->protected && test_bit(i, mpic->protected))
+			continue;
 		/* init hw */
 		mpic_irq_write(i, MPIC_INFO(IRQ_VECTOR_PRI), vecpri);
 		mpic_irq_write(i, MPIC_INFO(IRQ_DESTINATION),
···
 			mpic_eoi(mpic);
 		return NO_IRQ;
 	}
+	if (unlikely(mpic->protected && test_bit(src, mpic->protected))) {
+		if (printk_ratelimit())
+			printk(KERN_WARNING "%s: Got protected source %d !\n",
+			       mpic->name, (int)src);
+		mpic_eoi(mpic);
+		return NO_IRQ;
+	}
+
 	return irq_linear_revmap(mpic->irqhost, src);
 }
 

include/asm-powerpc/mpic.h

···
 	unsigned int		dcr_base;
 #endif
 
+	/* Protected sources */
+	unsigned long		*protected;
+
 #ifdef CONFIG_MPIC_WEIRD
 	/* Pointer to HW info array */
 	u32			*hw_set;