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>

4 files changed, 149 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index fe9a60ac81d8..f3b9b8775e41 100644
--- a/MAINTAINERS
+++ b/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>
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index c70476b34a53..d913aec85109 100644
--- a/drivers/irqchip/Kconfig
+++ b/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
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index d2df34a54d38..d27e3e3619e0 100644
--- a/drivers/irqchip/Makefile
+++ b/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
diff --git a/drivers/irqchip/irq-goldfish-pic.c b/drivers/irqchip/irq-goldfish-pic.c
new file mode 100644
index 000000000000..2a92f03c73e4
--- /dev/null
+++ b/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);