ARC: opencode arc_request_percpu_irq

- The idea is to remove the API usage since it has a subltle
  design flaw - relies on being called on cpu0 first. This is true for
  some early per cpu irqs such as TIMER/IPI, but not for late probed
  per cpu peripherals such a perf. And it's usage in perf has already
  bitten us once: see c6317bc7
  ("ARCv2: perf: Ensure perf intr gets enabled on all cores") where we
  ended up open coding it anyways

- The seeming duplication will go away once we start using cpu notifier
  for timer setup
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/irq.h

@@ -26,8 +26,5 @@
 
 extern void arc_init_IRQ(void);
 void arc_local_timer_setup(void);
-void arc_request_percpu_irq(int irq, int cpu,
-                            irqreturn_t (*isr)(int irq, void *dev),
-                            const char *irq_nm, void *percpu_dev);
 
 #endif

arch/arc/kernel/irq.c

@@ -50,32 +50,3 @@ void arch_do_IRQ(unsigned int irq, struct pt_regs *regs)
 	irq_exit();
 	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,
-                            void *percpu_dev)
-{
-	/* Boot cpu calls request, all call enable */
-	if (!cpu) {
-		int rc;
-
-		rc = request_percpu_irq(irq, isr, irq_nm, percpu_dev);
-		if (rc)
-			panic("Percpu IRQ request failed for %d\n", irq);
-	}
-
-	enable_percpu_irq(irq, 0);
-}

arch/arc/kernel/smp.c

@@ -346,6 +346,10 @@ irqreturn_t do_IPI(int irq, void *dev_id)
 
 /*
  * API called by platform code to hookup arch-common ISR to their IPI IRQ
+ *
+ * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map
+ * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise
+ * request_percpu_irq() below will fail
  */
 static DEFINE_PER_CPU(int, ipi_dev);
 
@@ -353,7 +357,16 @@ int smp_ipi_irq_setup(int cpu, int irq)
 {
 	int *dev = per_cpu_ptr(&ipi_dev, cpu);
 
-	arc_request_percpu_irq(irq, cpu, do_IPI, "IPI Interrupt", dev);
+	/* Boot cpu calls request, all call enable */
+	if (!cpu) {
+		int rc;
+
+		rc = request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev);
+		if (rc)
+			panic("Percpu IRQ request failed for %d\n", irq);
+	}
+
+	enable_percpu_irq(irq, 0);
 
 	return 0;
 }

arch/arc/kernel/time.c

@@ -251,14 +251,22 @@ void arc_local_timer_setup()
 {
 	struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 	int cpu = smp_processor_id();
+	int irq = TIMER0_IRQ;
 
 	evt->cpumask = cpumask_of(cpu);
 	clockevents_config_and_register(evt, arc_get_core_freq(),
 					0, ARC_TIMER_MAX);
 
-	/* setup the per-cpu timer IRQ handler - for all cpus */
-	arc_request_percpu_irq(TIMER0_IRQ, cpu, timer_irq_handler,
-			       "Timer0 (per-cpu-tick)", evt);
+	if (!cpu) {
+		int rc;
+
+		rc = request_percpu_irq(irq, timer_irq_handler,
+					"Timer0 (per-cpu-tick)", evt);
+		if (rc)
+			panic("Percpu IRQ request failed for TIMER\n");
+	}
+
+	enable_percpu_irq(irq, 0);
 }
 
 /*