ARC: [SMP] cpumask not needed in IPI send path

The current IPI sending callstack needlessly involves cpumask.

   arch_send_call_function_single_ipi(cpu) / smp_send_reschedule(cpu)
      ipi_send_msg(cpumask_of(cpu))	--> [cpu to cpumask]
         plat_smp_ops.ipi_send(callmap)
            for_each_cpu(callmap)	--> [cpuask to cpu]
               do_plat_specific_ipi_PER_CPU

Given that current backends are not capable of 1:N IPIs, lets simplify
the interface for now, by keeping "a" cpu all along.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/smp.h

@@ -46,13 +46,13 @@ extern int smp_ipi_irq_setup(int cpu, int irq);
  *
  * @info:		SoC SMP specific info for /proc/cpuinfo etc
  * @cpu_kick:		For Master to kickstart a cpu (optionally at a PC)
- * @ipi_send:		To send IPI to a @cpumask
+ * @ipi_send:		To send IPI to a @cpu
  * @ips_clear:		To clear IPI received by @cpu at @irq
  */
 struct plat_smp_ops {
 	const char 	*info;
 	void		(*cpu_kick)(int cpu, unsigned long pc);
-	void		(*ipi_send)(void *callmap);
+	void		(*ipi_send)(int cpu);
 	void		(*ipi_clear)(int cpu, int irq);
 };
 

arch/arc/kernel/smp.c

@@ -220,28 +220,33 @@ struct ipi_data {
 
 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
 
-static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
+static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
 {
+	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 	unsigned long flags;
-	unsigned int cpu;
 
 	local_irq_save(flags);
 
-	for_each_cpu(cpu, callmap) {
-		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
-		set_bit(msg, &ipi->bits);
-	}
+	set_bit(msg, &ipi->bits);
 
 	/* Call the platform specific cross-CPU call function  */
 	if (plat_smp_ops.ipi_send)
-		plat_smp_ops.ipi_send((void *)callmap);
+		plat_smp_ops.ipi_send(cpu);
 
 	local_irq_restore(flags);
 }
 
+static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
+{
+	unsigned int cpu;
+
+	for_each_cpu(cpu, callmap)
+		ipi_send_msg_one(cpu, msg);
+}
+
 void smp_send_reschedule(int cpu)
 {
-	ipi_send_msg(cpumask_of(cpu), IPI_RESCHEDULE);
+	ipi_send_msg_one(cpu, IPI_RESCHEDULE);
 }
 
 void smp_send_stop(void)
@@ -254,7 +259,7 @@ void smp_send_stop(void)
 
 void arch_send_call_function_single_ipi(int cpu)
 {
-	ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC);
+	ipi_send_msg_one(cpu, IPI_CALL_FUNC);
 }
 
 void arch_send_call_function_ipi_mask(const struct cpumask *mask)

arch/arc/plat-arcfpga/smp.c

@@ -88,13 +88,9 @@ void iss_model_init_smp(unsigned int cpu)
 	smp_ipi_irq_setup(cpu, IDU_INTERRUPT_0 + cpu);
 }
 
-static void iss_model_ipi_send(void *arg)
+static void iss_model_ipi_send(int cpu)
 {
-	struct cpumask *callmap = arg;
-	unsigned int cpu;
-
-	for_each_cpu(cpu, callmap)
-		idu_irq_assert(cpu);
+	idu_irq_assert(cpu);
 }
 
 static void iss_model_ipi_clear(int cpu, int irq)