irqchip/mmp: Do not use of_address_to_resource() to get mux regs

The "regs" property of the "mrvl,mmp2-mux-intc" devices are silly. They
are offsets from intc's base, not addresses on the parent bus. At this
point it probably can't be fixed.

On an OLPC XO-1.75 machine, the muxes are children of the intc, not the
axi bus, and thus of_address_to_resource() won't work. We should treat
the values as mere integers as opposed to bus addresses.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Link: https://lore.kernel.org/r/20190822092643.593488-7-lkundrak@v3.sk

drivers/irqchip/irq-mmp.c

@@ -422,9 +422,9 @@ IRQCHIP_DECLARE(mmp2_intc, "mrvl,mmp2-intc", mmp2_of_init);
 static int __init mmp2_mux_of_init(struct device_node *node,
 				   struct device_node *parent)
 {
-	struct resource res;
 	int i, ret, irq, j = 0;
 	u32 nr_irqs, mfp_irq;
+	u32 reg[4];
 
 	if (!parent)
 		return -ENODEV;
@@ -436,18 +436,22 @@ static int __init mmp2_mux_of_init(struct device_node *node,
 		pr_err("Not found mrvl,intc-nr-irqs property\n");
 		return -EINVAL;
 	}
-	ret = of_address_to_resource(node, 0, &res);
-	if (ret < 0) {
-		pr_err("Not found reg property\n");
-		return -EINVAL;
-	}
-	icu_data[i].reg_status = mmp_icu_base + res.start;
-	ret = of_address_to_resource(node, 1, &res);
+
+	/*
+	 * For historical reasons, the "regs" property of the
+	 * mrvl,mmp2-mux-intc is not a regular "regs" property containing
+	 * addresses on the parent bus, but offsets from the intc's base.
+	 * That is why we can't use of_address_to_resource() here.
+	 */
+	ret = of_property_read_variable_u32_array(node, "reg", reg,
+						  ARRAY_SIZE(reg),
+						  ARRAY_SIZE(reg));
 	if (ret < 0) {
 		pr_err("Not found reg property\n");
 		return -EINVAL;
 	}
-	icu_data[i].reg_mask = mmp_icu_base + res.start;
+	icu_data[i].reg_status = mmp_icu_base + reg[0];
+	icu_data[i].reg_mask = mmp_icu_base + reg[2];
 	icu_data[i].cascade_irq = irq_of_parse_and_map(node, 0);
 	if (!icu_data[i].cascade_irq)
 		return -EINVAL;