sparc32,leon: implement genirq CPU affinity

A simple implementation of CPU affinity, the first CPU in
the affinity CPU mask always takes the IRQ.
Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/leon_kernel.c

@@ -99,25 +99,68 @@ static inline unsigned long get_irqmask(unsigned int irq)
 	return mask;
 }
 
+#ifdef CONFIG_SMP
+static int irq_choose_cpu(const struct cpumask *affinity)
+{
+	cpumask_t mask;
+
+	cpus_and(mask, cpu_online_map, *affinity);
+	if (cpus_equal(mask, cpu_online_map) || cpus_empty(mask))
+		return 0;
+	else
+		return first_cpu(mask);
+}
+#else
+#define irq_choose_cpu(affinity) 0
+#endif
+
+static int leon_set_affinity(struct irq_data *data, const struct cpumask *dest,
+			     bool force)
+{
+	unsigned long mask, oldmask, flags;
+	int oldcpu, newcpu;
+
+	mask = (unsigned long)data->chip_data;
+	oldcpu = irq_choose_cpu(data->affinity);
+	newcpu = irq_choose_cpu(dest);
+
+	if (oldcpu == newcpu)
+		goto out;
+
+	/* unmask on old CPU first before enabling on the selected CPU */
+	spin_lock_irqsave(&leon_irq_lock, flags);
+	oldmask = LEON3_BYPASS_LOAD_PA(LEON_IMASK(oldcpu));
+	LEON3_BYPASS_STORE_PA(LEON_IMASK(oldcpu), (oldmask & ~mask));
+	oldmask = LEON3_BYPASS_LOAD_PA(LEON_IMASK(newcpu));
+	LEON3_BYPASS_STORE_PA(LEON_IMASK(newcpu), (oldmask | mask));
+	spin_unlock_irqrestore(&leon_irq_lock, flags);
+out:
+	return IRQ_SET_MASK_OK;
+}
+
 static void leon_unmask_irq(struct irq_data *data)
 {
 	unsigned long mask, oldmask, flags;
+	int cpu;
 
 	mask = (unsigned long)data->chip_data;
+	cpu = irq_choose_cpu(data->affinity);
 	spin_lock_irqsave(&leon_irq_lock, flags);
-	oldmask = LEON3_BYPASS_LOAD_PA(LEON_IMASK(0));
-	LEON3_BYPASS_STORE_PA(LEON_IMASK(0), (oldmask | mask));
+	oldmask = LEON3_BYPASS_LOAD_PA(LEON_IMASK(cpu));
+	LEON3_BYPASS_STORE_PA(LEON_IMASK(cpu), (oldmask | mask));
 	spin_unlock_irqrestore(&leon_irq_lock, flags);
 }
 
 static void leon_mask_irq(struct irq_data *data)
 {
 	unsigned long mask, oldmask, flags;
+	int cpu;
 
 	mask = (unsigned long)data->chip_data;
+	cpu = irq_choose_cpu(data->affinity);
 	spin_lock_irqsave(&leon_irq_lock, flags);
-	oldmask = LEON3_BYPASS_LOAD_PA(LEON_IMASK(0));
-	LEON3_BYPASS_STORE_PA(LEON_IMASK(0), (oldmask & ~mask));
+	oldmask = LEON3_BYPASS_LOAD_PA(LEON_IMASK(cpu));
+	LEON3_BYPASS_STORE_PA(LEON_IMASK(cpu), (oldmask & ~mask));
 	spin_unlock_irqrestore(&leon_irq_lock, flags);
 }
 
@@ -150,6 +193,7 @@ static struct irq_chip leon_irq = {
 	.irq_mask		= leon_mask_irq,
 	.irq_unmask		= leon_unmask_irq,
 	.irq_eoi		= leon_eoi_irq,
+	.irq_set_affinity	= leon_set_affinity,
 };
 
 /*