irqchip: Add a driver for the Microsemi Ocelot controller

The Microsemi Ocelot SoC has a pretty simple IRQ controller in its ICPU
block. Add a driver for it.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/Kconfig

@@ -286,6 +286,11 @@ config IRQ_MXS
 	select IRQ_DOMAIN
 	select STMP_DEVICE
 
+config MSCC_OCELOT_IRQ
+	bool
+	select IRQ_DOMAIN
+	select GENERIC_IRQ_CHIP
+
 config MVEBU_GICP
 	bool
 

drivers/irqchip/Makefile

@@ -72,6 +72,7 @@ obj-$(CONFIG_ARCH_SA1100)		+= irq-sa11x0.o
 obj-$(CONFIG_INGENIC_IRQ)		+= irq-ingenic.o
 obj-$(CONFIG_IMX_GPCV2)			+= irq-imx-gpcv2.o
 obj-$(CONFIG_PIC32_EVIC)		+= irq-pic32-evic.o
+obj-$(CONFIG_MSCC_OCELOT_IRQ)		+= irq-mscc-ocelot.o
 obj-$(CONFIG_MVEBU_GICP)		+= irq-mvebu-gicp.o
 obj-$(CONFIG_MVEBU_ICU)			+= irq-mvebu-icu.o
 obj-$(CONFIG_MVEBU_ODMI)		+= irq-mvebu-odmi.o

drivers/irqchip/irq-mscc-ocelot.c

@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Microsemi Ocelot IRQ controller driver
+ *
+ * Copyright (c) 2017 Microsemi Corporation
+ */
+#include <linux/bitops.h>
+#include <linux/irq.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/interrupt.h>
+
+#define ICPU_CFG_INTR_INTR_STICKY	0x10
+#define ICPU_CFG_INTR_INTR_ENA		0x18
+#define ICPU_CFG_INTR_INTR_ENA_CLR	0x1c
+#define ICPU_CFG_INTR_INTR_ENA_SET	0x20
+#define ICPU_CFG_INTR_DST_INTR_IDENT(x)	(0x38 + 0x4 * (x))
+#define ICPU_CFG_INTR_INTR_TRIGGER(x)	(0x5c + 0x4 * (x))
+
+#define OCELOT_NR_IRQ 24
+
+static void ocelot_irq_unmask(struct irq_data *data)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(data);
+	struct irq_chip_type *ct = irq_data_get_chip_type(data);
+	unsigned int mask = data->mask;
+	u32 val;
+
+	irq_gc_lock(gc);
+	val = irq_reg_readl(gc, ICPU_CFG_INTR_INTR_TRIGGER(0)) |
+	      irq_reg_readl(gc, ICPU_CFG_INTR_INTR_TRIGGER(1));
+	if (!(val & mask))
+		irq_reg_writel(gc, mask, ICPU_CFG_INTR_INTR_STICKY);
+
+	*ct->mask_cache &= ~mask;
+	irq_reg_writel(gc, mask, ICPU_CFG_INTR_INTR_ENA_SET);
+	irq_gc_unlock(gc);
+}
+
+static void ocelot_irq_handler(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	struct irq_domain *d = irq_desc_get_handler_data(desc);
+	struct irq_chip_generic *gc = irq_get_domain_generic_chip(d, 0);
+	u32 reg = irq_reg_readl(gc, ICPU_CFG_INTR_DST_INTR_IDENT(0));
+
+	chained_irq_enter(chip, desc);
+
+	while (reg) {
+		u32 hwirq = __fls(reg);
+
+		generic_handle_irq(irq_find_mapping(d, hwirq));
+		reg &= ~(BIT(hwirq));
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
+static int __init ocelot_irq_init(struct device_node *node,
+				  struct device_node *parent)
+{
+	struct irq_domain *domain;
+	struct irq_chip_generic *gc;
+	int parent_irq, ret;
+
+	parent_irq = irq_of_parse_and_map(node, 0);
+	if (!parent_irq)
+		return -EINVAL;
+
+	domain = irq_domain_add_linear(node, OCELOT_NR_IRQ,
+				       &irq_generic_chip_ops, NULL);
+	if (!domain) {
+		pr_err("%s: unable to add irq domain\n", node->name);
+		return -ENOMEM;
+	}
+
+	ret = irq_alloc_domain_generic_chips(domain, OCELOT_NR_IRQ, 1,
+					     "icpu", handle_level_irq,
+					     0, 0, 0);
+	if (ret) {
+		pr_err("%s: unable to alloc irq domain gc\n", node->name);
+		goto err_domain_remove;
+	}
+
+	gc = irq_get_domain_generic_chip(domain, 0);
+	gc->reg_base = of_iomap(node, 0);
+	if (!gc->reg_base) {
+		pr_err("%s: unable to map resource\n", node->name);
+		ret = -ENOMEM;
+		goto err_gc_free;
+	}
+
+	gc->chip_types[0].regs.ack = ICPU_CFG_INTR_INTR_STICKY;
+	gc->chip_types[0].regs.mask = ICPU_CFG_INTR_INTR_ENA_CLR;
+	gc->chip_types[0].chip.irq_ack = irq_gc_ack_set_bit;
+	gc->chip_types[0].chip.irq_mask = irq_gc_mask_set_bit;
+	gc->chip_types[0].chip.irq_unmask = ocelot_irq_unmask;
+
+	/* Mask and ack all interrupts */
+	irq_reg_writel(gc, 0, ICPU_CFG_INTR_INTR_ENA);
+	irq_reg_writel(gc, 0xffffffff, ICPU_CFG_INTR_INTR_STICKY);
+
+	irq_set_chained_handler_and_data(parent_irq, ocelot_irq_handler,
+					 domain);
+
+	return 0;
+
+err_gc_free:
+	irq_free_generic_chip(gc);
+
+err_domain_remove:
+	irq_domain_remove(domain);
+
+	return ret;
+}
+IRQCHIP_DECLARE(ocelot_icpu, "mscc,ocelot-icpu-intr", ocelot_irq_init);