arm: mvebu: Improve the SMP support of the interrupt controller

This patch makes the interrupt controller driver more SMP aware for
the Armada XP SoCs. It adds the support for the per-CPU irq. It also
adds the implementation for the set_affinity hook.

Patch initialy wrote by Yehuda Yitschak and reworked by Gregory
CLEMENT.
Signed-off-by: Yehuda Yitschak <yehuday@marvell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-xp.dtsi

@@ -30,7 +30,7 @@ L2: l2-cache {
 	};
 
 	mpic: interrupt-controller@d0020000 {
-	      reg = <0xd0020a00 0x1d0>,
+	      reg = <0xd0020a00 0x2d0>,
 		    <0xd0021070 0x58>;
 	};
 

arch/arm/mach-mvebu/irq-armada-370-xp.c

@@ -34,6 +34,7 @@
 #define ARMADA_370_XP_INT_CONTROL		(0x00)
 #define ARMADA_370_XP_INT_SET_ENABLE_OFFS	(0x30)
 #define ARMADA_370_XP_INT_CLEAR_ENABLE_OFFS	(0x34)
+#define ARMADA_370_XP_INT_SOURCE_CTL(irq)	(0x100 + irq*4)
 
 #define ARMADA_370_XP_CPU_INTACK_OFFS		(0x44)
 
@@ -41,28 +42,90 @@
 #define ARMADA_370_XP_IN_DRBEL_MSK_OFFS          (0xc)
 #define ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS        (0x8)
 
+#define ARMADA_370_XP_MAX_PER_CPU_IRQS		(28)
+
 #define ACTIVE_DOORBELLS			(8)
 
+static DEFINE_RAW_SPINLOCK(irq_controller_lock);
+
 static void __iomem *per_cpu_int_base;
 static void __iomem *main_int_base;
 static struct irq_domain *armada_370_xp_mpic_domain;
 
+/*
+ * In SMP mode:
+ * For shared global interrupts, mask/unmask global enable bit
+ * For CPU interrtups, mask/unmask the calling CPU's bit
+ */
 static void armada_370_xp_irq_mask(struct irq_data *d)
 {
+#ifdef CONFIG_SMP
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
+
+	if (hwirq > ARMADA_370_XP_MAX_PER_CPU_IRQS)
+		writel(hwirq, main_int_base +
+				ARMADA_370_XP_INT_CLEAR_ENABLE_OFFS);
+	else
+		writel(hwirq, per_cpu_int_base +
+				ARMADA_370_XP_INT_SET_MASK_OFFS);
+#else
 	writel(irqd_to_hwirq(d),
 	       per_cpu_int_base + ARMADA_370_XP_INT_SET_MASK_OFFS);
+#endif
 }
 
 static void armada_370_xp_irq_unmask(struct irq_data *d)
 {
+#ifdef CONFIG_SMP
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
+
+	if (hwirq > ARMADA_370_XP_MAX_PER_CPU_IRQS)
+		writel(hwirq, main_int_base +
+				ARMADA_370_XP_INT_SET_ENABLE_OFFS);
+	else
+		writel(hwirq, per_cpu_int_base +
+				ARMADA_370_XP_INT_CLEAR_MASK_OFFS);
+#else
 	writel(irqd_to_hwirq(d),
 	       per_cpu_int_base + ARMADA_370_XP_INT_CLEAR_MASK_OFFS);
+#endif
 }
 
 #ifdef CONFIG_SMP
 static int armada_xp_set_affinity(struct irq_data *d,
 				  const struct cpumask *mask_val, bool force)
 {
+	unsigned long reg;
+	unsigned long new_mask = 0;
+	unsigned long online_mask = 0;
+	unsigned long count = 0;
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
+	int cpu;
+
+	for_each_cpu(cpu, mask_val) {
+		new_mask |= 1 << cpu_logical_map(cpu);
+		count++;
+	}
+
+	/*
+	 * Forbid mutlicore interrupt affinity
+	 * This is required since the MPIC HW doesn't limit
+	 * several CPUs from acknowledging the same interrupt.
+	 */
+	if (count > 1)
+		return -EINVAL;
+
+	for_each_cpu(cpu, cpu_online_mask)
+		online_mask |= 1 << cpu_logical_map(cpu);
+
+	raw_spin_lock(&irq_controller_lock);
+
+	reg = readl(main_int_base + ARMADA_370_XP_INT_SOURCE_CTL(hwirq));
+	reg = (reg & (~online_mask)) | new_mask;
+	writel(reg, main_int_base + ARMADA_370_XP_INT_SOURCE_CTL(hwirq));
+
+	raw_spin_unlock(&irq_controller_lock);
+
 	return 0;
 }
 #endif
@@ -155,6 +218,15 @@ static int __init armada_370_xp_mpic_of_init(struct device_node *node,
 
 #ifdef CONFIG_SMP
 	armada_xp_mpic_smp_cpu_init();
+
+	/*
+	 * Set the default affinity from all CPUs to the boot cpu.
+	 * This is required since the MPIC doesn't limit several CPUs
+	 * from acknowledging the same interrupt.
+	 */
+	cpumask_clear(irq_default_affinity);
+	cpumask_set_cpu(smp_processor_id(), irq_default_affinity);
+
 #endif
 
 	return 0;