/*
 * Marvell Orion SoCs IRQ chip driver.
 *
 * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <asm/exception.h>
#include <asm/mach/irq.h>

/*
 * Orion SoC main interrupt controller
 */
#define ORION_IRQS_PER_CHIP		32

#define ORION_IRQ_CAUSE			0x00
#define ORION_IRQ_MASK			0x04
#define ORION_IRQ_FIQ_MASK		0x08
#define ORION_IRQ_ENDP_MASK		0x0c

static struct irq_domain *orion_irq_domain;

static void
__exception_irq_entry orion_handle_irq(struct pt_regs *regs)
{
	struct irq_domain_chip_generic *dgc = orion_irq_domain->gc;
	int n, base = 0;

	for (n = 0; n < dgc->num_chips; n++, base += ORION_IRQS_PER_CHIP) {
		struct irq_chip_generic *gc =
			irq_get_domain_generic_chip(orion_irq_domain, base);
		u32 stat = readl_relaxed(gc->reg_base + ORION_IRQ_CAUSE) &
			gc->mask_cache;
		while (stat) {
			u32 hwirq = __fls(stat);
			handle_domain_irq(orion_irq_domain,
					  gc->irq_base + hwirq, regs);
			stat &= ~(1 << hwirq);
		}
	}
}

static int __init orion_irq_init(struct device_node *np,
				 struct device_node *parent)
{
	unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
	int n, ret, base, num_chips = 0;
	struct resource r;

	/* count number of irq chips by valid reg addresses */
	while (of_address_to_resource(np, num_chips, &r) == 0)
		num_chips++;

	orion_irq_domain = irq_domain_add_linear(np,
				num_chips * ORION_IRQS_PER_CHIP,
				&irq_generic_chip_ops, NULL);
	if (!orion_irq_domain)
		panic("%pOFn: unable to add irq domain\n", np);

	ret = irq_alloc_domain_generic_chips(orion_irq_domain,
				ORION_IRQS_PER_CHIP, 1, np->full_name,
				handle_level_irq, clr, 0,
				IRQ_GC_INIT_MASK_CACHE);
	if (ret)
		panic("%pOFn: unable to alloc irq domain gc\n", np);

	for (n = 0, base = 0; n < num_chips; n++, base += ORION_IRQS_PER_CHIP) {
		struct irq_chip_generic *gc =
			irq_get_domain_generic_chip(orion_irq_domain, base);

		of_address_to_resource(np, n, &r);

		if (!request_mem_region(r.start, resource_size(&r), np->name))
			panic("%pOFn: unable to request mem region %d",
			      np, n);

		gc->reg_base = ioremap(r.start, resource_size(&r));
		if (!gc->reg_base)
			panic("%pOFn: unable to map resource %d", np, n);

		gc->chip_types[0].regs.mask = ORION_IRQ_MASK;
		gc->chip_types[0].chip.irq_mask = irq_gc_mask_clr_bit;
		gc->chip_types[0].chip.irq_unmask = irq_gc_mask_set_bit;

		/* mask all interrupts */
		writel(0, gc->reg_base + ORION_IRQ_MASK);
	}

	set_handle_irq(orion_handle_irq);
	return 0;
}
IRQCHIP_DECLARE(orion_intc, "marvell,orion-intc", orion_irq_init);

/*
 * Orion SoC bridge interrupt controller
 */
#define ORION_BRIDGE_IRQ_CAUSE	0x00
#define ORION_BRIDGE_IRQ_MASK	0x04

static void orion_bridge_irq_handler(struct irq_desc *desc)
{
	struct irq_domain *d = irq_desc_get_handler_data(desc);

	struct irq_chip_generic *gc = irq_get_domain_generic_chip(d, 0);
	u32 stat = readl_relaxed(gc->reg_base + ORION_BRIDGE_IRQ_CAUSE) &
		   gc->mask_cache;

	while (stat) {
		u32 hwirq = __fls(stat);

		generic_handle_irq(irq_find_mapping(d, gc->irq_base + hwirq));
		stat &= ~(1 << hwirq);
	}
}

/*
 * Bridge IRQ_CAUSE is asserted regardless of IRQ_MASK register.
 * To avoid interrupt events on stale irqs, we clear them before unmask.
 */
static unsigned int orion_bridge_irq_startup(struct irq_data *d)
{
	struct irq_chip_type *ct = irq_data_get_chip_type(d);

	ct->chip.irq_ack(d);
	ct->chip.irq_unmask(d);
	return 0;
}

static int __init orion_bridge_irq_init(struct device_node *np,
					struct device_node *parent)
{
	unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
	struct resource r;
	struct irq_domain *domain;
	struct irq_chip_generic *gc;
	int ret, irq, nrirqs = 32;

	/* get optional number of interrupts provided */
	of_property_read_u32(np, "marvell,#interrupts", &nrirqs);

	domain = irq_domain_add_linear(np, nrirqs,
				       &irq_generic_chip_ops, NULL);
	if (!domain) {
		pr_err("%pOFn: unable to add irq domain\n", np);
		return -ENOMEM;
	}

	ret = irq_alloc_domain_generic_chips(domain, nrirqs, 1, np->name,
			     handle_edge_irq, clr, 0, IRQ_GC_INIT_MASK_CACHE);
	if (ret) {
		pr_err("%pOFn: unable to alloc irq domain gc\n", np);
		return ret;
	}

	ret = of_address_to_resource(np, 0, &r);
	if (ret) {
		pr_err("%pOFn: unable to get resource\n", np);
		return ret;
	}

	if (!request_mem_region(r.start, resource_size(&r), np->name)) {
		pr_err("%s: unable to request mem region\n", np->name);
		return -ENOMEM;
	}

	/* Map the parent interrupt for the chained handler */
	irq = irq_of_parse_and_map(np, 0);
	if (irq <= 0) {
		pr_err("%pOFn: unable to parse irq\n", np);
		return -EINVAL;
	}

	gc = irq_get_domain_generic_chip(domain, 0);
	gc->reg_base = ioremap(r.start, resource_size(&r));
	if (!gc->reg_base) {
		pr_err("%pOFn: unable to map resource\n", np);
		return -ENOMEM;
	}

	gc->chip_types[0].regs.ack = ORION_BRIDGE_IRQ_CAUSE;
	gc->chip_types[0].regs.mask = ORION_BRIDGE_IRQ_MASK;
	gc->chip_types[0].chip.irq_startup = orion_bridge_irq_startup;
	gc->chip_types[0].chip.irq_ack = irq_gc_ack_clr_bit;
	gc->chip_types[0].chip.irq_mask = irq_gc_mask_clr_bit;
	gc->chip_types[0].chip.irq_unmask = irq_gc_mask_set_bit;

	/* mask and clear all interrupts */
	writel(0, gc->reg_base + ORION_BRIDGE_IRQ_MASK);
	writel(0, gc->reg_base + ORION_BRIDGE_IRQ_CAUSE);

	irq_set_chained_handler_and_data(irq, orion_bridge_irq_handler,
					 domain);

	return 0;
}
IRQCHIP_DECLARE(orion_bridge_intc,
		"marvell,orion-bridge-intc", orion_bridge_irq_init);