[RFC PATCH v2] Add IPI entry for CPU UP

[Zhaoyang Huang]

In some ARM SOCs, IPI interrupt is used for hotplug in one cpu, that is,
sending a IPI to the core in WFI and powerdown status. So Add a IPI
entry for handle this kind of cpu up interrupt
Launching the IPI can be done within PSCI, while there will be one unknown
type of IPI as the dest core come up to the kernel world which will bring a
warning so far.So add such type of IPI to handle the interrupt.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxxxxxx>
---
 arch/arm64/include/asm/hardirq.h |    2 +-
 arch/arm64/kernel/smp.c          |   10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/hardirq.h b/arch/arm64/include/asm/hardirq.h
index a57601f..bb4edb7 100644
--- a/arch/arm64/include/asm/hardirq.h
+++ b/arch/arm64/include/asm/hardirq.h
@@ -20,7 +20,7 @@
 #include <linux/threads.h>
 #include <asm/irq.h>
 
-#define NR_IPI	5
+#define NR_IPI   6
 
 typedef struct {
 	unsigned int __softirq_pending;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index b1adc51..20e63c9 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -70,6 +70,7 @@ enum ipi_msg_type {
 	IPI_CPU_STOP,
 	IPI_TIMER,
 	IPI_IRQ_WORK,
+	IPI_CPU_UP,
 };
 
 /*
@@ -627,6 +628,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = {
 	S(IPI_CPU_STOP, "CPU stop interrupts"),
 	S(IPI_TIMER, "Timer broadcast interrupts"),
 	S(IPI_IRQ_WORK, "IRQ work interrupts"),
+	S(IPI_CPU_UP, "Hotplug cpu up by ipi"),
 };
 
 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
@@ -746,6 +748,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 		irq_exit();
 		break;
 #endif
+       case IPI_CPU_UP:
+               break;
 
 	default:
 		pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
@@ -798,3 +802,9 @@ int setup_profiling_timer(unsigned int multiplier)
 {
 	return -EINVAL;
 }
+
+void smp_send_cpuup(int cpu)
+{
+       smp_cross_call(cpumask_of(cpu), IPI_CPU_UP);
+}
+
-- 
1.7.9.5