irqchip/sifive-plic: Fix chip_data access within a hierarchy

The plic driver crashes in plic_irq_unmask() when the interrupt is within a
hierarchy, as it picks the top-level chip_data instead of its local one.

Using irq_data_get_irq_chip_data() instead of irq_get_chip_data() solves
the issue for good.

Fixes: f1ad1133 ("irqchip/sifive-plic: Add support for multiple PLICs")
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
[maz: rewrote commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Link: https://lore.kernel.org/r/20201029023738.127472-1-greentime.hu@sifive.com

drivers/irqchip/irq-sifive-plic.c

@@ -99,7 +99,7 @@ static inline void plic_irq_toggle(const struct cpumask *mask,
 				   struct irq_data *d, int enable)
 {
 	int cpu;
-	struct plic_priv *priv = irq_get_chip_data(d->irq);
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 
 	writel(enable, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
 	for_each_cpu(cpu, mask) {
@@ -115,7 +115,7 @@ static void plic_irq_unmask(struct irq_data *d)
 {
 	struct cpumask amask;
 	unsigned int cpu;
-	struct plic_priv *priv = irq_get_chip_data(d->irq);
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 
 	cpumask_and(&amask, &priv->lmask, cpu_online_mask);
 	cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
@@ -127,7 +127,7 @@ static void plic_irq_unmask(struct irq_data *d)
 
 static void plic_irq_mask(struct irq_data *d)
 {
-	struct plic_priv *priv = irq_get_chip_data(d->irq);
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 
 	plic_irq_toggle(&priv->lmask, d, 0);
 }
@@ -138,7 +138,7 @@ static int plic_set_affinity(struct irq_data *d,
 {
 	unsigned int cpu;
 	struct cpumask amask;
-	struct plic_priv *priv = irq_get_chip_data(d->irq);
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 
 	cpumask_and(&amask, &priv->lmask, mask_val);