/*
 * OMAP2+ common Power & Reset Management (PRM) IP block functions
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Tero Kristo <t-kristo@ti.com>
 *
 * 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.
 *
 *
 * For historical purposes, the API used to configure the PRM
 * interrupt handler refers to it as the "PRCM interrupt."  The
 * underlying registers are located in the PRM on OMAP3/4.
 *
 * XXX This code should eventually be moved to a PRM driver.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/slab.h>

#include <plat/common.h>
#include <plat/prcm.h>
#include <plat/irqs.h>

#include "prm2xxx_3xxx.h"
#include "prm44xx.h"

/*
 * OMAP_PRCM_MAX_NR_PENDING_REG: maximum number of PRM_IRQ*_MPU regs
 * XXX this is technically not needed, since
 * omap_prcm_register_chain_handler() could allocate this based on the
 * actual amount of memory needed for the SoC
 */
#define OMAP_PRCM_MAX_NR_PENDING_REG		2

/*
 * prcm_irq_chips: an array of all of the "generic IRQ chips" in use
 * by the PRCM interrupt handler code.  There will be one 'chip' per
 * PRM_{IRQSTATUS,IRQENABLE}_MPU register pair.  (So OMAP3 will have
 * one "chip" and OMAP4 will have two.)
 */
static struct irq_chip_generic **prcm_irq_chips;

/*
 * prcm_irq_setup: the PRCM IRQ parameters for the hardware the code
 * is currently running on.  Defined and passed by initialization code
 * that calls omap_prcm_register_chain_handler().
 */
static struct omap_prcm_irq_setup *prcm_irq_setup;

/* Private functions */

/*
 * Move priority events from events to priority_events array
 */
static void omap_prcm_events_filter_priority(unsigned long *events,
	unsigned long *priority_events)
{
	int i;

	for (i = 0; i < prcm_irq_setup->nr_regs; i++) {
		priority_events[i] =
			events[i] & prcm_irq_setup->priority_mask[i];
		events[i] ^= priority_events[i];
	}
}

/*
 * PRCM Interrupt Handler
 *
 * This is a common handler for the OMAP PRCM interrupts. Pending
 * interrupts are detected by a call to prcm_pending_events and
 * dispatched accordingly. Clearing of the wakeup events should be
 * done by the SoC specific individual handlers.
 */
static void omap_prcm_irq_handler(unsigned int irq, struct irq_desc *desc)
{
	unsigned long pending[OMAP_PRCM_MAX_NR_PENDING_REG];
	unsigned long priority_pending[OMAP_PRCM_MAX_NR_PENDING_REG];
	struct irq_chip *chip = irq_desc_get_chip(desc);
	unsigned int virtirq;
	int nr_irqs = prcm_irq_setup->nr_regs * 32;

	/*
	 * If we are suspended, mask all interrupts from PRCM level,
	 * this does not ack them, and they will be pending until we
	 * re-enable the interrupts, at which point the
	 * omap_prcm_irq_handler will be executed again.  The
	 * _save_and_clear_irqen() function must ensure that the PRM
	 * write to disable all IRQs has reached the PRM before
	 * returning, or spurious PRCM interrupts may occur during
	 * suspend.
	 */
	if (prcm_irq_setup->suspended) {
		prcm_irq_setup->save_and_clear_irqen(prcm_irq_setup->saved_mask);
		prcm_irq_setup->suspend_save_flag = true;
	}

	/*
	 * Loop until all pending irqs are handled, since
	 * generic_handle_irq() can cause new irqs to come
	 */
	while (!prcm_irq_setup->suspended) {
		prcm_irq_setup->read_pending_irqs(pending);

		/* No bit set, then all IRQs are handled */
		if (find_first_bit(pending, nr_irqs) >= nr_irqs)
			break;

		omap_prcm_events_filter_priority(pending, priority_pending);

		/*
		 * Loop on all currently pending irqs so that new irqs
		 * cannot starve previously pending irqs
		 */

		/* Serve priority events first */
		for_each_set_bit(virtirq, priority_pending, nr_irqs)
			generic_handle_irq(prcm_irq_setup->base_irq + virtirq);

		/* Serve normal events next */
		for_each_set_bit(virtirq, pending, nr_irqs)
			generic_handle_irq(prcm_irq_setup->base_irq + virtirq);
	}
	if (chip->irq_ack)
		chip->irq_ack(&desc->irq_data);
	if (chip->irq_eoi)
		chip->irq_eoi(&desc->irq_data);
	chip->irq_unmask(&desc->irq_data);

	prcm_irq_setup->ocp_barrier(); /* avoid spurious IRQs */
}

/* Public functions */

/**
 * omap_prcm_event_to_irq - given a PRCM event name, returns the
 * corresponding IRQ on which the handler should be registered
 * @name: name of the PRCM interrupt bit to look up - see struct omap_prcm_irq
 *
 * Returns the Linux internal IRQ ID corresponding to @name upon success,
 * or -ENOENT upon failure.
 */
int omap_prcm_event_to_irq(const char *name)
{
	int i;

	if (!prcm_irq_setup || !name)
		return -ENOENT;

	for (i = 0; i < prcm_irq_setup->nr_irqs; i++)
		if (!strcmp(prcm_irq_setup->irqs[i].name, name))
			return prcm_irq_setup->base_irq +
				prcm_irq_setup->irqs[i].offset;

	return -ENOENT;
}

/**
 * omap_prcm_irq_cleanup - reverses memory allocated and other steps
 * done by omap_prcm_register_chain_handler()
 *
 * No return value.
 */
void omap_prcm_irq_cleanup(void)
{
	int i;

	if (!prcm_irq_setup) {
		pr_err("PRCM: IRQ handler not initialized; cannot cleanup\n");
		return;
	}

	if (prcm_irq_chips) {
		for (i = 0; i < prcm_irq_setup->nr_regs; i++) {
			if (prcm_irq_chips[i])
				irq_remove_generic_chip(prcm_irq_chips[i],
					0xffffffff, 0, 0);
			prcm_irq_chips[i] = NULL;
		}
		kfree(prcm_irq_chips);
		prcm_irq_chips = NULL;
	}

	kfree(prcm_irq_setup->saved_mask);
	prcm_irq_setup->saved_mask = NULL;

	kfree(prcm_irq_setup->priority_mask);
	prcm_irq_setup->priority_mask = NULL;

	irq_set_chained_handler(prcm_irq_setup->irq, NULL);

	if (prcm_irq_setup->base_irq > 0)
		irq_free_descs(prcm_irq_setup->base_irq,
			prcm_irq_setup->nr_regs * 32);
	prcm_irq_setup->base_irq = 0;
}

void omap_prcm_irq_prepare(void)
{
	prcm_irq_setup->suspended = true;
}

void omap_prcm_irq_complete(void)
{
	prcm_irq_setup->suspended = false;

	/* If we have not saved the masks, do not attempt to restore */
	if (!prcm_irq_setup->suspend_save_flag)
		return;

	prcm_irq_setup->suspend_save_flag = false;

	/*
	 * Re-enable all masked PRCM irq sources, this causes the PRCM
	 * interrupt to fire immediately if the events were masked
	 * previously in the chain handler
	 */
	prcm_irq_setup->restore_irqen(prcm_irq_setup->saved_mask);
}

/**
 * omap_prcm_register_chain_handler - initializes the prcm chained interrupt
 * handler based on provided parameters
 * @irq_setup: hardware data about the underlying PRM/PRCM
 *
 * Set up the PRCM chained interrupt handler on the PRCM IRQ.  Sets up
 * one generic IRQ chip per PRM interrupt status/enable register pair.
 * Returns 0 upon success, -EINVAL if called twice or if invalid
 * arguments are passed, or -ENOMEM on any other error.
 */
int omap_prcm_register_chain_handler(struct omap_prcm_irq_setup *irq_setup)
{
	int nr_regs = irq_setup->nr_regs;
	u32 mask[OMAP_PRCM_MAX_NR_PENDING_REG];
	int offset, i;
	struct irq_chip_generic *gc;
	struct irq_chip_type *ct;

	if (!irq_setup)
		return -EINVAL;

	if (prcm_irq_setup) {
		pr_err("PRCM: already initialized; won't reinitialize\n");
		return -EINVAL;
	}

	if (nr_regs > OMAP_PRCM_MAX_NR_PENDING_REG) {
		pr_err("PRCM: nr_regs too large\n");
		return -EINVAL;
	}

	prcm_irq_setup = irq_setup;

	prcm_irq_chips = kzalloc(sizeof(void *) * nr_regs, GFP_KERNEL);
	prcm_irq_setup->saved_mask = kzalloc(sizeof(u32) * nr_regs, GFP_KERNEL);
	prcm_irq_setup->priority_mask = kzalloc(sizeof(u32) * nr_regs,
		GFP_KERNEL);

	if (!prcm_irq_chips || !prcm_irq_setup->saved_mask ||
	    !prcm_irq_setup->priority_mask) {
		pr_err("PRCM: kzalloc failed\n");
		goto err;
	}

	memset(mask, 0, sizeof(mask));

	for (i = 0; i < irq_setup->nr_irqs; i++) {
		offset = irq_setup->irqs[i].offset;
		mask[offset >> 5] |= 1 << (offset & 0x1f);
		if (irq_setup->irqs[i].priority)
			irq_setup->priority_mask[offset >> 5] |=
				1 << (offset & 0x1f);
	}

	irq_set_chained_handler(irq_setup->irq, omap_prcm_irq_handler);

	irq_setup->base_irq = irq_alloc_descs(-1, 0, irq_setup->nr_regs * 32,
		0);

	if (irq_setup->base_irq < 0) {
		pr_err("PRCM: failed to allocate irq descs: %d\n",
			irq_setup->base_irq);
		goto err;
	}

	for (i = 0; i < irq_setup->nr_regs; i++) {
		gc = irq_alloc_generic_chip("PRCM", 1,
			irq_setup->base_irq + i * 32, prm_base,
			handle_level_irq);

		if (!gc) {
			pr_err("PRCM: failed to allocate generic chip\n");
			goto err;
		}
		ct = gc->chip_types;
		ct->chip.irq_ack = irq_gc_ack_set_bit;
		ct->chip.irq_mask = irq_gc_mask_clr_bit;
		ct->chip.irq_unmask = irq_gc_mask_set_bit;

		ct->regs.ack = irq_setup->ack + i * 4;
		ct->regs.mask = irq_setup->mask + i * 4;

		irq_setup_generic_chip(gc, mask[i], 0, IRQ_NOREQUEST, 0);
		prcm_irq_chips[i] = gc;
	}

	return 0;

err:
	omap_prcm_irq_cleanup();
	return -ENOMEM;
}