[PATCH v4 4/8] irqchip/irq-goldfish-pic: Add Goldfish PIC driver

[Aleksandar Markovic <aleksandar.markovic@rt-rk.com>]

From: Miodrag Dinic <miodrag.dinic@imgtec.com>

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@imgtec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
---
 MAINTAINERS                        |   1 +
 drivers/irqchip/Kconfig            |   8 ++
 drivers/irqchip/Makefile           |   1 +
 drivers/irqchip/irq-goldfish-pic.c | 145 +++++++++++++++++++++++++++++++++++++
 4 files changed, 155 insertions(+)
 create mode 100644 drivers/irqchip/irq-goldfish-pic.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 013da1d..6426875 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -844,6 +844,7 @@ ANDROID GOLDFISH PIC DRIVER
 M:	Miodrag Dinic <miodrag.dinic@imgtec.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@imgtec.com>
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index f1fd5f4..21fab14 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -306,3 +306,11 @@ config QCOM_IRQ_COMBINER
 	help
 	  Say yes here to add support for the IRQ combiner devices embedded
 	  in Qualcomm Technologies chips.
+
+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.
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index e88d856..ade04a1 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -78,3 +78,4 @@ obj-$(CONFIG_EZNPS_GIC)			+= irq-eznps.o
 obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o irq-aspeed-i2c-ic.o
 obj-$(CONFIG_STM32_EXTI) 		+= irq-stm32-exti.o
 obj-$(CONFIG_QCOM_IRQ_COMBINER)		+= qcom-irq-combiner.o
+obj-$(CONFIG_GOLDFISH_PIC) 		+= irq-goldfish-pic.o
diff --git a/drivers/irqchip/irq-goldfish-pic.c b/drivers/irqchip/irq-goldfish-pic.c
new file mode 100644
index 0000000..948c35e
--- /dev/null
+++ b/drivers/irqchip/irq-goldfish-pic.c
@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2017 Imagination Technologies Ltd.	All rights reserved
+ *	Author: Miodrag Dinic <miodrag.dinic@imgtec.com>
+ *
+ * This file implements interrupt controller driver for MIPS Goldfish PIC.
+ *
+ * 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.
+ */
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqdomain.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#include <asm/setup.h>
+
+/* 0..7 MIPS CPU interrupts */
+#define GF_CPU_IRQ_PIC		(MIPS_CPU_IRQ_BASE + 2)
+#define GF_CPU_IRQ_COMPARE	(MIPS_CPU_IRQ_BASE + 7)
+
+#define GF_NR_IRQS		40
+/* 8..39 Cascaded Goldfish PIC interrupts */
+#define GF_IRQ_OFFSET		8
+
+#define GF_PIC_NUMBER		0x04
+#define GF_PIC_DISABLE_ALL	0x08
+#define GF_PIC_DISABLE		0x0c
+#define GF_PIC_ENABLE		0x10
+
+static struct irq_domain *irq_domain;
+static void __iomem *gf_pic_base;
+
+static inline void unmask_goldfish_irq(struct irq_data *d)
+{
+	writel(d->hwirq - GF_IRQ_OFFSET,
+	       gf_pic_base + GF_PIC_ENABLE);
+	irq_enable_hazard();
+}
+
+static inline void mask_goldfish_irq(struct irq_data *d)
+{
+	writel(d->hwirq - GF_IRQ_OFFSET,
+	       gf_pic_base + GF_PIC_DISABLE);
+	irq_disable_hazard();
+}
+
+static struct irq_chip goldfish_irq_controller = {
+	.name		= "Goldfish PIC",
+	.irq_ack	= mask_goldfish_irq,
+	.irq_mask	= mask_goldfish_irq,
+	.irq_mask_ack	= mask_goldfish_irq,
+	.irq_unmask	= unmask_goldfish_irq,
+	.irq_eoi	= unmask_goldfish_irq,
+	.irq_disable	= mask_goldfish_irq,
+	.irq_enable	= unmask_goldfish_irq,
+};
+
+static void goldfish_irq_dispatch(void)
+{
+	u32 irq;
+	u32 virq;
+
+	irq = readl(gf_pic_base + GF_PIC_NUMBER);
+	if (irq == 0) {
+		/* Timer interrupt */
+		do_IRQ(GF_CPU_IRQ_COMPARE);
+		return;
+	}
+
+	virq = irq_linear_revmap(irq_domain, irq);
+	virq += GF_IRQ_OFFSET;
+	do_IRQ(virq);
+}
+
+static void goldfish_ip2_irq_dispatch(struct irq_desc *desc)
+{
+	unsigned long pending = read_c0_cause() & read_c0_status() & ST0_IM;
+
+	if (pending & CAUSEF_IP2)
+		goldfish_irq_dispatch();
+	else
+		spurious_interrupt();
+}
+
+static int goldfish_pic_map(struct irq_domain *d, unsigned int irq,
+			    irq_hw_number_t hw)
+{
+	if (cpu_has_vint)
+		set_vi_handler(hw, goldfish_irq_dispatch);
+
+	irq_set_chip_and_handler(irq, &goldfish_irq_controller,
+				 handle_level_irq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops gf_pic_irq_domain_ops = {
+	.map = goldfish_pic_map,
+	.xlate = irq_domain_xlate_onetwocell,
+};
+
+static struct irqaction cascade = {
+	.handler	= no_action,
+	.flags		= IRQF_PROBE_SHARED,
+	.name		= "cascade",
+};
+
+static void __init __goldfish_pic_init(struct device_node *of_node)
+{
+	gf_pic_base = of_iomap(of_node, 0);
+	if (!gf_pic_base)
+		panic("Failed to map Goldfish PIC base : No such device!");
+
+	/* Mask interrupts. */
+	writel(1, gf_pic_base + GF_PIC_DISABLE_ALL);
+
+	if (!cpu_has_vint)
+		irq_set_chained_handler(GF_CPU_IRQ_PIC,
+					goldfish_ip2_irq_dispatch);
+
+	setup_irq(GF_CPU_IRQ_PIC, &cascade);
+
+	irq_domain = irq_domain_add_legacy(of_node, GF_NR_IRQS,
+					   GF_IRQ_OFFSET, 0,
+					   &gf_pic_irq_domain_ops, NULL);
+	if (!irq_domain)
+		panic("Failed to add irqdomain for Goldfish PIC");
+}
+
+int __init goldfish_pic_of_init(struct device_node *of_node,
+				struct device_node *parent)
+{
+	__goldfish_pic_init(of_node);
+	return 0;
+}
+
+IRQCHIP_DECLARE(google_gf_pic, "google,goldfish-pic", goldfish_pic_of_init);
+
-- 
2.7.4