ARM: GIC: don't disable software generated interrupts

Software generated interrupts (SGI) are used for IPIs by the kernel.
While previous revisions of the GIC hardware were specified not to
implement enable bits for SGIs, more recent hardware is now permitted
to implement these bits in a per-CPU banked register.

The priority registers for the PPI and SGIs are also per-CPU banked
registers, so ensure that these are also appropriately initialized.
Reported-by: Scott Valentine <svalentine@concentris-systems.com>
Acked-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/common/gic.c

@@ -251,15 +251,16 @@ void __init gic_dist_init(unsigned int gic_nr, void __iomem *base,
 		writel(cpumask, base + GIC_DIST_TARGET + i * 4 / 4);
 
 	/*
-	 * Set priority on all interrupts.
+	 * Set priority on all global interrupts.
 	 */
-	for (i = 0; i < max_irq; i += 4)
+	for (i = 32; i < max_irq; i += 4)
 		writel(0xa0a0a0a0, base + GIC_DIST_PRI + i * 4 / 4);
 
 	/*
-	 * Disable all interrupts.
+	 * Disable all interrupts.  Leave the PPI and SGIs alone
+	 * as these enables are banked registers.
 	 */
-	for (i = 0; i < max_irq; i += 32)
+	for (i = 32; i < max_irq; i += 32)
 		writel(0xffffffff, base + GIC_DIST_ENABLE_CLEAR + i * 4 / 32);
 
 	/*
@@ -277,11 +278,30 @@ void __init gic_dist_init(unsigned int gic_nr, void __iomem *base,
 
 void __cpuinit gic_cpu_init(unsigned int gic_nr, void __iomem *base)
 {
+	void __iomem *dist_base;
+	int i;
+
 	if (gic_nr >= MAX_GIC_NR)
 		BUG();
 
+	dist_base = gic_data[gic_nr].dist_base;
+	BUG_ON(!dist_base);
+
 	gic_data[gic_nr].cpu_base = base;
 
+	/*
+	 * Deal with the banked PPI and SGI interrupts - disable all
+	 * PPI interrupts, ensure all SGI interrupts are enabled.
+	 */
+	writel(0xffff0000, dist_base + GIC_DIST_ENABLE_CLEAR);
+	writel(0x0000ffff, dist_base + GIC_DIST_ENABLE_SET);
+
+	/*
+	 * Set priority on PPI and SGI interrupts
+	 */
+	for (i = 0; i < 32; i += 4)
+		writel(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4);
+
 	writel(0xf0, base + GIC_CPU_PRIMASK);
 	writel(1, base + GIC_CPU_CTRL);
 }