irqchip: Add a driver for Cortina Gemini

As a part of transitioning the Gemini platform to device tree we
create this clean, device-tree-only irqchip driver.

Cc: Janos Laube <janos.dev@gmail.com>
Cc: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Cc: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/Makefile

@@ -6,6 +6,7 @@ obj-$(CONFIG_ATH79)			+= irq-ath79-misc.o
 obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2835.o
 obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2836.o
 obj-$(CONFIG_ARCH_EXYNOS)		+= exynos-combiner.o
+obj-$(CONFIG_ARCH_GEMINI)		+= irq-gemini.o
 obj-$(CONFIG_ARCH_HIP04)		+= irq-hip04.o
 obj-$(CONFIG_ARCH_LPC32XX)		+= irq-lpc32xx.o
 obj-$(CONFIG_ARCH_MMP)			+= irq-mmp.o

drivers/irqchip/irq-gemini.c

+/*
+ * irqchip for the Cortina Systems Gemini Copyright (C) 2017 Linus
+ * Walleij <linus.walleij@linaro.org>
+ *
+ * Based on arch/arm/mach-gemini/irq.c
+ * Copyright (C) 2001-2006 Storlink, Corp.
+ * Copyright (C) 2008-2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
+ */
+#include <linux/bitops.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/versatile-fpga.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/cpu.h>
+
+#include <asm/exception.h>
+#include <asm/mach/irq.h>
+
+#define GEMINI_NUM_IRQS 32
+
+#define GEMINI_IRQ_SOURCE(base_addr)	(base_addr + 0x00)
+#define GEMINI_IRQ_MASK(base_addr)	(base_addr + 0x04)
+#define GEMINI_IRQ_CLEAR(base_addr)	(base_addr + 0x08)
+#define GEMINI_IRQ_MODE(base_addr)	(base_addr + 0x0C)
+#define GEMINI_IRQ_POLARITY(base_addr)	(base_addr + 0x10)
+#define GEMINI_IRQ_STATUS(base_addr)	(base_addr + 0x14)
+#define GEMINI_FIQ_SOURCE(base_addr)	(base_addr + 0x20)
+#define GEMINI_FIQ_MASK(base_addr)	(base_addr + 0x24)
+#define GEMINI_FIQ_CLEAR(base_addr)	(base_addr + 0x28)
+#define GEMINI_FIQ_MODE(base_addr)	(base_addr + 0x2C)
+#define GEMINI_FIQ_POLARITY(base_addr)	(base_addr + 0x30)
+#define GEMINI_FIQ_STATUS(base_addr)	(base_addr + 0x34)
+
+/**
+ * struct gemini_irq_data - irq data container for the Gemini IRQ controller
+ * @base: memory offset in virtual memory
+ * @chip: chip container for this instance
+ * @domain: IRQ domain for this instance
+ */
+struct gemini_irq_data {
+	void __iomem *base;
+	struct irq_chip chip;
+	struct irq_domain *domain;
+};
+
+static void gemini_irq_mask(struct irq_data *d)
+{
+	struct gemini_irq_data *g = irq_data_get_irq_chip_data(d);
+	unsigned int mask;
+
+	mask = readl(GEMINI_IRQ_MASK(g->base));
+	mask &= ~BIT(irqd_to_hwirq(d));
+	writel(mask, GEMINI_IRQ_MASK(g->base));
+}
+
+static void gemini_irq_unmask(struct irq_data *d)
+{
+	struct gemini_irq_data *g = irq_data_get_irq_chip_data(d);
+	unsigned int mask;
+
+	mask = readl(GEMINI_IRQ_MASK(g->base));
+	mask |= BIT(irqd_to_hwirq(d));
+	writel(mask, GEMINI_IRQ_MASK(g->base));
+}
+
+static void gemini_irq_ack(struct irq_data *d)
+{
+	struct gemini_irq_data *g = irq_data_get_irq_chip_data(d);
+
+	writel(BIT(irqd_to_hwirq(d)), GEMINI_IRQ_CLEAR(g->base));
+}
+
+static int gemini_irq_set_type(struct irq_data *d, unsigned int trigger)
+{
+	struct gemini_irq_data *g = irq_data_get_irq_chip_data(d);
+	int offset = irqd_to_hwirq(d);
+	u32 mode, polarity;
+
+	mode = readl(GEMINI_IRQ_MODE(g->base));
+	polarity = readl(GEMINI_IRQ_POLARITY(g->base));
+
+	if (trigger & (IRQ_TYPE_LEVEL_HIGH)) {
+		irq_set_handler_locked(d, handle_level_irq);
+		/* Disable edge detection */
+		mode &= ~BIT(offset);
+		polarity &= ~BIT(offset);
+	} else if (trigger & IRQ_TYPE_EDGE_RISING) {
+		irq_set_handler_locked(d, handle_edge_irq);
+		mode |= BIT(offset);
+		polarity |= BIT(offset);
+	} else if (trigger & IRQ_TYPE_EDGE_FALLING) {
+		irq_set_handler_locked(d, handle_edge_irq);
+		mode |= BIT(offset);
+		polarity &= ~BIT(offset);
+	} else {
+		irq_set_handler_locked(d, handle_bad_irq);
+		pr_warn("GEMINI IRQ: no supported trigger selected for line %d\n",
+			offset);
+	}
+
+	writel(mode, GEMINI_IRQ_MODE(g->base));
+	writel(polarity, GEMINI_IRQ_POLARITY(g->base));
+
+	return 0;
+}
+
+static struct irq_chip gemini_irq_chip = {
+	.name		= "GEMINI",
+	.irq_ack	= gemini_irq_ack,
+	.irq_mask	= gemini_irq_mask,
+	.irq_unmask	= gemini_irq_unmask,
+	.irq_set_type	= gemini_irq_set_type,
+};
+
+/* Local static for the IRQ entry call */
+static struct gemini_irq_data girq;
+
+asmlinkage void __exception_irq_entry gemini_irqchip_handle_irq(struct pt_regs *regs)
+{
+	struct gemini_irq_data *g = &girq;
+	int irq;
+	u32 status;
+
+	while ((status = readl(GEMINI_IRQ_STATUS(g->base)))) {
+		irq = ffs(status) - 1;
+		handle_domain_irq(g->domain, irq, regs);
+	}
+}
+
+static int gemini_irqdomain_map(struct irq_domain *d, unsigned int irq,
+				irq_hw_number_t hwirq)
+{
+	struct gemini_irq_data *g = d->host_data;
+
+	irq_set_chip_data(irq, g);
+	/* All IRQs should set up their type, flags as bad by default */
+	irq_set_chip_and_handler(irq, &gemini_irq_chip, handle_bad_irq);
+	irq_set_probe(irq);
+
+	return 0;
+}
+
+static void gemini_irqdomain_unmap(struct irq_domain *d, unsigned int irq)
+{
+	irq_set_chip_and_handler(irq, NULL, NULL);
+	irq_set_chip_data(irq, NULL);
+}
+
+static const struct irq_domain_ops gemini_irqdomain_ops = {
+	.map = gemini_irqdomain_map,
+	.unmap = gemini_irqdomain_unmap,
+	.xlate = irq_domain_xlate_onetwocell,
+};
+
+int __init gemini_of_init_irq(struct device_node *node,
+			      struct device_node *parent)
+{
+	struct gemini_irq_data *g = &girq;
+
+	/*
+	 * Disable the idle handler by default since it is buggy
+	 * For more info see arch/arm/mach-gemini/idle.c
+	 */
+	cpu_idle_poll_ctrl(true);
+
+	g->base = of_iomap(node, 0);
+	WARN(!g->base, "unable to map gemini irq registers\n");
+
+	/* Disable all interrupts */
+	writel(0, GEMINI_IRQ_MASK(g->base));
+	writel(0, GEMINI_FIQ_MASK(g->base));
+
+	g->domain = irq_domain_add_simple(node, GEMINI_NUM_IRQS, 0,
+					  &gemini_irqdomain_ops, g);
+	set_handle_irq(gemini_irqchip_handle_irq);
+
+	return 0;
+}
+IRQCHIP_DECLARE(gemini, "cortina,gemini-interrupt-controller",
+		gemini_of_init_irq);