irqchip/irq-bcm7120-l2: Switch to IRQCHIP_PLATFORM_DRIVER

Allow the user selection and building of this interrupt controller
driver as a module since it is used on ARM/ARM64 based systems as a
second level interrupt controller hanging off the ARM GIC and is
therefore loadable during boot.

To avoid using of_irq_count() which is not exported towards module,
switch the driver to use the platform_device provided by the irqchip
platform driver code and resolve the number of interrupts using
platform_irq_count().

Signed-off-by: Florian Fainelli <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/irqchip/Kconfig

···
 	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
 
 config BCM7120_L2_IRQ
-	bool
+	tristate "Broadcom STB 7120-style L2 interrupt controller driver"
+	depends on ARCH_BRCMSTB || BMIPS_GENERIC
+	default ARCH_BRCMSTB || BMIPS_GENERIC
 	select GENERIC_IRQ_CHIP
 	select IRQ_DOMAIN
 

drivers/irqchip/irq-bcm7120-l2.c

···
 {
 	unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
 	struct bcm7120_l2_intc_data *data;
+	struct platform_device *pdev;
 	struct irq_chip_generic *gc;
 	struct irq_chip_type *ct;
 	int ret = 0;
···
 	if (!data)
 		return -ENOMEM;
 
-	data->num_parent_irqs = of_irq_count(dn);
+	pdev = of_find_device_by_node(dn);
+	if (!pdev) {
+		ret = -ENODEV;
+		goto out_free_data;
+	}
+
+	data->num_parent_irqs = platform_irq_count(pdev);
 	if (data->num_parent_irqs <= 0) {
 		pr_err("invalid number of parent interrupts\n");
 		ret = -ENOMEM;
···
 		if (data->map_base[idx])
 			iounmap(data->map_base[idx]);
 	}
+out_free_data:
 	kfree(data);
 	return ret;
 }
···
 				     "BCM3380 L2");
 }
 
-IRQCHIP_DECLARE(bcm7120_l2_intc, "brcm,bcm7120-l2-intc",
-		bcm7120_l2_intc_probe_7120);
-
-IRQCHIP_DECLARE(bcm3380_l2_intc, "brcm,bcm3380-l2-intc",
-		bcm7120_l2_intc_probe_3380);
+IRQCHIP_PLATFORM_DRIVER_BEGIN(bcm7120_l2)
+IRQCHIP_MATCH("brcm,bcm7120-l2-intc", bcm7120_l2_intc_probe_7120)
+IRQCHIP_MATCH("brcm,bcm3380-l2-intc", bcm7120_l2_intc_probe_3380)
+IRQCHIP_PLATFORM_DRIVER_END(bcm7120_l2)
+MODULE_DESCRIPTION("Broadcom STB 7120-style L2 interrupt controller driver");
+MODULE_LICENSE("GPL v2");