irqchip: brcmstb-l2: Add Broadcom Set Top Box Level-2 interrupt controller

This patch adds support for the Level-2 interrupt controller hardware
found in Broadcom Set Top Box System-on-a-Chip devices. This interrupt
controller is implemented using the generic IRQ chip driver with
separate enable and disable registers.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Link: https://lkml.kernel.org/r/1400892054-24457-2-git-send-email-f.fainelli@gmail.com
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/Kconfig

@@ -30,6 +30,12 @@ config ARM_VIC_NR
 	  The maximum number of VICs available in the system, for
 	  power management.
 
+config BRCMSTB_L2_IRQ
+	bool
+	depends on ARM
+	select GENERIC_IRQ_CHIP
+	select IRQ_DOMAIN
+
 config DW_APB_ICTL
 	bool
 	select IRQ_DOMAIN

drivers/irqchip/Makefile

@@ -29,3 +29,4 @@ obj-$(CONFIG_TB10X_IRQC)		+= irq-tb10x.o
 obj-$(CONFIG_XTENSA)			+= irq-xtensa-pic.o
 obj-$(CONFIG_XTENSA_MX)			+= irq-xtensa-mx.o
 obj-$(CONFIG_IRQ_CROSSBAR)		+= irq-crossbar.o
+obj-$(CONFIG_BRCMSTB_L2_IRQ)		+= irq-brcmstb-l2.o

drivers/irqchip/irq-brcmstb-l2.c

@@ -0,0 +1,202 @@
+/*
+ * Generic Broadcom Set Top Box Level 2 Interrupt controller driver
+ *
+ * Copyright (C) 2014 Broadcom Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME	": " fmt
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/irqdomain.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+
+#include <asm/mach/irq.h>
+
+#include "irqchip.h"
+
+/* Register offsets in the L2 interrupt controller */
+#define CPU_STATUS	0x00
+#define CPU_SET		0x04
+#define CPU_CLEAR	0x08
+#define CPU_MASK_STATUS	0x0c
+#define CPU_MASK_SET	0x10
+#define CPU_MASK_CLEAR	0x14
+
+/* L2 intc private data structure */
+struct brcmstb_l2_intc_data {
+	int parent_irq;
+	void __iomem *base;
+	struct irq_domain *domain;
+	bool can_wake;
+	u32 saved_mask; /* for suspend/resume */
+};
+
+static void brcmstb_l2_intc_irq_handle(unsigned int irq, struct irq_desc *desc)
+{
+	struct brcmstb_l2_intc_data *b = irq_desc_get_handler_data(desc);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	u32 status;
+
+	chained_irq_enter(chip, desc);
+
+	status = __raw_readl(b->base + CPU_STATUS) &
+		~(__raw_readl(b->base + CPU_MASK_STATUS));
+
+	if (status == 0) {
+		do_bad_IRQ(irq, desc);
+		goto out;
+	}
+
+	do {
+		irq = ffs(status) - 1;
+		/* ack at our level */
+		__raw_writel(1 << irq, b->base + CPU_CLEAR);
+		status &= ~(1 << irq);
+		generic_handle_irq(irq_find_mapping(b->domain, irq));
+	} while (status);
+out:
+	chained_irq_exit(chip, desc);
+}
+
+static void brcmstb_l2_intc_suspend(struct irq_data *d)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
+	struct brcmstb_l2_intc_data *b = gc->private;
+
+	irq_gc_lock(gc);
+	/* Save the current mask */
+	b->saved_mask = __raw_readl(b->base + CPU_MASK_STATUS);
+
+	if (b->can_wake) {
+		/* Program the wakeup mask */
+		__raw_writel(~gc->wake_active, b->base + CPU_MASK_SET);
+		__raw_writel(gc->wake_active, b->base + CPU_MASK_CLEAR);
+	}
+	irq_gc_unlock(gc);
+}
+
+static void brcmstb_l2_intc_resume(struct irq_data *d)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
+	struct brcmstb_l2_intc_data *b = gc->private;
+
+	irq_gc_lock(gc);
+	/* Clear unmasked non-wakeup interrupts */
+	__raw_writel(~b->saved_mask & ~gc->wake_active, b->base + CPU_CLEAR);
+
+	/* Restore the saved mask */
+	__raw_writel(b->saved_mask, b->base + CPU_MASK_SET);
+	__raw_writel(~b->saved_mask, b->base + CPU_MASK_CLEAR);
+	irq_gc_unlock(gc);
+}
+
+int __init brcmstb_l2_intc_of_init(struct device_node *np,
+					struct device_node *parent)
+{
+	unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
+	struct brcmstb_l2_intc_data *data;
+	struct irq_chip_generic *gc;
+	struct irq_chip_type *ct;
+	int ret;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->base = of_iomap(np, 0);
+	if (!data->base) {
+		pr_err("failed to remap intc L2 registers\n");
+		ret = -ENOMEM;
+		goto out_free;
+	}
+
+	/* Disable all interrupts by default */
+	__raw_writel(0xffffffff, data->base + CPU_MASK_SET);
+	__raw_writel(0xffffffff, data->base + CPU_CLEAR);
+
+	data->parent_irq = irq_of_parse_and_map(np, 0);
+	if (data->parent_irq < 0) {
+		pr_err("failed to find parent interrupt\n");
+		ret = data->parent_irq;
+		goto out_unmap;
+	}
+
+	data->domain = irq_domain_add_linear(np, 32,
+				&irq_generic_chip_ops, NULL);
+	if (!data->domain) {
+		ret = -ENOMEM;
+		goto out_unmap;
+	}
+
+	/* Allocate a single Generic IRQ chip for this node */
+	ret = irq_alloc_domain_generic_chips(data->domain, 32, 1,
+				np->full_name, handle_level_irq, clr, 0, 0);
+	if (ret) {
+		pr_err("failed to allocate generic irq chip\n");
+		goto out_free_domain;
+	}
+
+	/* Set the IRQ chaining logic */
+	irq_set_handler_data(data->parent_irq, data);
+	irq_set_chained_handler(data->parent_irq, brcmstb_l2_intc_irq_handle);
+
+	gc = irq_get_domain_generic_chip(data->domain, 0);
+	gc->reg_base = data->base;
+	gc->private = data;
+	ct = gc->chip_types;
+
+	ct->chip.irq_ack = irq_gc_ack_set_bit;
+	ct->regs.ack = CPU_CLEAR;
+
+	ct->chip.irq_mask = irq_gc_mask_disable_reg;
+	ct->regs.disable = CPU_MASK_SET;
+
+	ct->chip.irq_unmask = irq_gc_unmask_enable_reg;
+	ct->regs.enable = CPU_MASK_CLEAR;
+
+	ct->chip.irq_suspend = brcmstb_l2_intc_suspend;
+	ct->chip.irq_resume = brcmstb_l2_intc_resume;
+
+	if (of_property_read_bool(np, "brcm,irq-can-wake")) {
+		data->can_wake = true;
+		/* This IRQ chip can wake the system, set all child interrupts
+		 * in wake_enabled mask
+		 */
+		gc->wake_enabled = 0xffffffff;
+		ct->chip.irq_set_wake = irq_gc_set_wake;
+	}
+
+	pr_info("registered L2 intc (mem: 0x%p, parent irq: %d)\n",
+			data->base, data->parent_irq);
+
+	return 0;
+
+out_free_domain:
+	irq_domain_remove(data->domain);
+out_unmap:
+	iounmap(data->base);
+out_free:
+	kfree(data);
+	return ret;
+}
+IRQCHIP_DECLARE(brcmstb_l2_intc, "brcm,l2-intc", brcmstb_l2_intc_of_init);