From: Marc Zyngier <marc.zyngier@arm.com>
Date: Tue, 9 Aug 2016 06:50:44 +0000 (+0100)
Subject: irqchip/gic: Allow self-SGIs for SMP on UP configurations
X-Git-Tag: v4.8-rc4~4^2~4^2~2
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=059e232089e45b0befc9933d31209c225e08b426;p=linux.git

irqchip/gic: Allow self-SGIs for SMP on UP configurations

On systems where a single CPU is present, the GIC may not support
having SGIs delivered to a target list. In that case, we use the
self-SGI mechanism to allow the interrupt to be delivered locally.

Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---

diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index c2cab572c511..390fac59c6bc 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -769,6 +769,13 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
 	int cpu;
 	unsigned long flags, map = 0;
 
+	if (unlikely(nr_cpu_ids == 1)) {
+		/* Only one CPU? let's do a self-IPI... */
+		writel_relaxed(2 << 24 | irq,
+			       gic_data_dist_base(&gic_data[0]) + GIC_DIST_SOFTINT);
+		return;
+	}
+
 	raw_spin_lock_irqsave(&irq_controller_lock, flags);
 
 	/* Convert our logical CPU mask into a physical one. */