Linux-libre 4.4-gnupck-4.4-gnu

1 files changed, 32 insertions, 13 deletions

diff --git a/arch/arc/kernel/irq.c b/arch/arc/kernel/irq.c
index 2989a7bcf..ba17f8528 100644
--- a/arch/arc/kernel/irq.c
+++ b/arch/arc/kernel/irq.c
@@ -10,6 +10,7 @@
 #include <linux/interrupt.h>
 #include <linux/irqchip.h>
 #include <asm/mach_desc.h>
+#include <asm/smp.h>
 
 /*
  * Late Interrupt system init called from start_kernel for Boot CPU only
@@ -19,17 +20,20 @@
  */
 void __init init_IRQ(void)
 {
-	/* Any external intc can be setup here */
-	if (machine_desc->init_irq)
-		machine_desc->init_irq();
-
-	/* process the entire interrupt tree in one go */
+	/*
+	 * process the entire interrupt tree in one go
+	 * Any external intc will be setup provided DT chains them
+	 * properly
+	 */
 	irqchip_init();
 
 #ifdef CONFIG_SMP
-	/* Master CPU can initialize it's side of IPI */
-	if (machine_desc->init_smp)
-		machine_desc->init_smp(smp_processor_id());
+	/* a SMP H/w block could do IPI IRQ request here */
+	if (plat_smp_ops.init_per_cpu)
+		plat_smp_ops.init_per_cpu(smp_processor_id());
+
+	if (machine_desc->init_per_cpu)
+		machine_desc->init_per_cpu(smp_processor_id());
 #endif
 }
 
@@ -47,6 +51,18 @@ void arch_do_IRQ(unsigned int irq, struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
+/*
+ * API called for requesting percpu interrupts - called by each CPU
+ *  - For boot CPU, actually request the IRQ with genirq core + enables
+ *  - For subsequent callers only enable called locally
+ *
+ * Relies on being called by boot cpu first (i.e. request called ahead) of
+ * any enable as expected by genirq. Hence Suitable only for TIMER, IPI
+ * which are guaranteed to be setup on boot core first.
+ * Late probed peripherals such as perf can't use this as there no guarantee
+ * of being called on boot CPU first.
+ */
+
 void arc_request_percpu_irq(int irq, int cpu,
                             irqreturn_t (*isr)(int irq, void *dev),
                             const char *irq_nm,
@@ -56,14 +72,17 @@ void arc_request_percpu_irq(int irq, int cpu,
 	if (!cpu) {
 		int rc;
 
+#ifdef CONFIG_ISA_ARCOMPACT
 		/*
-		 * These 2 calls are essential to making percpu IRQ APIs work
-		 * Ideally these details could be hidden in irq chip map function
-		 * but the issue is IPIs IRQs being static (non-DT) and platform
-		 * specific, so we can't identify them there.
+		 * A subsequent request_percpu_irq() fails if percpu_devid is
+		 * not set. That in turns sets NOAUTOEN, meaning each core needs
+		 * to call enable_percpu_irq()
+		 *
+		 * For ARCv2, this is done in irq map function since we know
+		 * which irqs are strictly per cpu
 		 */
 		irq_set_percpu_devid(irq);
-		irq_modify_status(irq, IRQ_NOAUTOEN, 0);  /* @irq, @clr, @set */
+#endif
 
 		rc = request_percpu_irq(irq, isr, irq_nm, percpu_dev);
 		if (rc)