irqchip/irq-goldfish-pic: Add Goldfish PIC driver

Add device driver for a virtual programmable interrupt controller

The virtual PIC is designed as a device tree-based interrupt controller.

The compatible string used by OS for binding the driver is
"google,goldfish-pic".

Signed-off-by: Miodrag Dinic <miodrag.dinic@mips.com>
Signed-off-by: Goran Ferenc <goran.ferenc@mips.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@mips.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

MAINTAINERS

@@ -871,6 +871,7 @@ ANDROID GOLDFISH PIC DRIVER
 M:	Miodrag Dinic <miodrag.dinic@mips.com>
 S:	Supported
 F:	Documentation/devicetree/bindings/interrupt-controller/google,goldfish-pic.txt
+F:	drivers/irqchip/irq-goldfish-pic.c
 
 ANDROID GOLDFISH RTC DRIVER
 M:	Miodrag Dinic <miodrag.dinic@mips.com>

drivers/irqchip/Kconfig

@@ -343,4 +343,12 @@ config MESON_IRQ_GPIO
        help
          Support Meson SoC Family GPIO Interrupt Multiplexer
 
+config GOLDFISH_PIC
+       bool "Goldfish programmable interrupt controller"
+       depends on MIPS && (GOLDFISH || COMPILE_TEST)
+       select IRQ_DOMAIN
+       help
+         Say yes here to enable Goldfish interrupt controller driver used
+         for Goldfish based virtual platforms.
+
 endmenu

drivers/irqchip/Makefile

@@ -84,3 +84,4 @@ obj-$(CONFIG_QCOM_IRQ_COMBINER)		+= qcom-irq-combiner.o
 obj-$(CONFIG_IRQ_UNIPHIER_AIDET)	+= irq-uniphier-aidet.o
 obj-$(CONFIG_ARCH_SYNQUACER)		+= irq-sni-exiu.o
 obj-$(CONFIG_MESON_IRQ_GPIO)		+= irq-meson-gpio.o
+obj-$(CONFIG_GOLDFISH_PIC) 		+= irq-goldfish-pic.o

drivers/irqchip/irq-goldfish-pic.c

@@ -0,0 +1,139 @@
+/*
+ * Driver for MIPS Goldfish Programmable Interrupt Controller.
+ *
+ * Author: Miodrag Dinic <miodrag.dinic@mips.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define GFPIC_NR_IRQS			32
+
+/* 8..39 Cascaded Goldfish PIC interrupts */
+#define GFPIC_IRQ_BASE			8
+
+#define GFPIC_REG_IRQ_PENDING		0x04
+#define GFPIC_REG_IRQ_DISABLE_ALL	0x08
+#define GFPIC_REG_IRQ_DISABLE		0x0c
+#define GFPIC_REG_IRQ_ENABLE		0x10
+
+struct goldfish_pic_data {
+	void __iomem *base;
+	struct irq_domain *irq_domain;
+};
+
+static void goldfish_pic_cascade(struct irq_desc *desc)
+{
+	struct goldfish_pic_data *gfpic = irq_desc_get_handler_data(desc);
+	struct irq_chip *host_chip = irq_desc_get_chip(desc);
+	u32 pending, hwirq, virq;
+
+	chained_irq_enter(host_chip, desc);
+
+	pending = readl(gfpic->base + GFPIC_REG_IRQ_PENDING);
+	while (pending) {
+		hwirq = __fls(pending);
+		virq = irq_linear_revmap(gfpic->irq_domain, hwirq);
+		generic_handle_irq(virq);
+		pending &= ~(1 << hwirq);
+	}
+
+	chained_irq_exit(host_chip, desc);
+}
+
+static const struct irq_domain_ops goldfish_irq_domain_ops = {
+	.xlate = irq_domain_xlate_onecell,
+};
+
+static int __init goldfish_pic_of_init(struct device_node *of_node,
+				       struct device_node *parent)
+{
+	struct goldfish_pic_data *gfpic;
+	struct irq_chip_generic *gc;
+	struct irq_chip_type *ct;
+	unsigned int parent_irq;
+	int ret = 0;
+
+	gfpic = kzalloc(sizeof(*gfpic), GFP_KERNEL);
+	if (!gfpic) {
+		ret = -ENOMEM;
+		goto out_err;
+	}
+
+	parent_irq = irq_of_parse_and_map(of_node, 0);
+	if (!parent_irq) {
+		pr_err("Failed to map parent IRQ!\n");
+		ret = -EINVAL;
+		goto out_free;
+	}
+
+	gfpic->base = of_iomap(of_node, 0);
+	if (!gfpic->base) {
+		pr_err("Failed to map base address!\n");
+		ret = -ENOMEM;
+		goto out_unmap_irq;
+	}
+
+	/* Mask interrupts. */
+	writel(1, gfpic->base + GFPIC_REG_IRQ_DISABLE_ALL);
+
+	gc = irq_alloc_generic_chip("GFPIC", 1, GFPIC_IRQ_BASE, gfpic->base,
+				    handle_level_irq);
+	if (!gc) {
+		pr_err("Failed to allocate chip structures!\n");
+		ret = -ENOMEM;
+		goto out_iounmap;
+	}
+
+	ct = gc->chip_types;
+	ct->regs.enable = GFPIC_REG_IRQ_ENABLE;
+	ct->regs.disable = GFPIC_REG_IRQ_DISABLE;
+	ct->chip.irq_unmask = irq_gc_unmask_enable_reg;
+	ct->chip.irq_mask = irq_gc_mask_disable_reg;
+
+	irq_setup_generic_chip(gc, IRQ_MSK(GFPIC_NR_IRQS), 0,
+			       IRQ_NOPROBE | IRQ_LEVEL, 0);
+
+	gfpic->irq_domain = irq_domain_add_legacy(of_node, GFPIC_NR_IRQS,
+						  GFPIC_IRQ_BASE, 0,
+						  &goldfish_irq_domain_ops,
+						  NULL);
+	if (!gfpic->irq_domain) {
+		pr_err("Failed to add irqdomain!\n");
+		ret = -ENOMEM;
+		goto out_destroy_generic_chip;
+	}
+
+	irq_set_chained_handler_and_data(parent_irq,
+					 goldfish_pic_cascade, gfpic);
+
+	pr_info("Successfully registered.\n");
+	return 0;
+
+out_destroy_generic_chip:
+	irq_destroy_generic_chip(gc, IRQ_MSK(GFPIC_NR_IRQS),
+				 IRQ_NOPROBE | IRQ_LEVEL, 0);
+out_iounmap:
+	iounmap(gfpic->base);
+out_unmap_irq:
+	irq_dispose_mapping(parent_irq);
+out_free:
+	kfree(gfpic);
+out_err:
+	pr_err("Failed to initialize! (errno = %d)\n", ret);
+	return ret;
+}
+
+IRQCHIP_DECLARE(google_gf_pic, "google,goldfish-pic", goldfish_pic_of_init);