/*
 * Copyright (c) 2017, Linaro Ltd.  All rights reserved.
 *
 * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/slab.h>

#include "timer-of.h"

/**
 * timer_of_irq_exit - Release the interrupt
 * @of_irq: an of_timer_irq structure pointer
 *
 * Free the irq resource
 */
static __init void timer_of_irq_exit(struct of_timer_irq *of_irq)
{
        struct timer_of *to = container_of(of_irq, struct timer_of, of_irq);

        struct clock_event_device *clkevt = &to->clkevt;

        of_irq->percpu ? free_percpu_irq(of_irq->irq, clkevt) :
                free_irq(of_irq->irq, clkevt);
}

/**
 * timer_of_irq_init - Request the interrupt
 * @np: a device tree node pointer
 * @of_irq: an of_timer_irq structure pointer
 *
 * Get the interrupt number from the DT from its definition and
 * request it. The interrupt is gotten by falling back the following way:
 *
 * - Get interrupt number by name
 * - Get interrupt number by index
 *
 * When the interrupt is per CPU, 'request_percpu_irq()' is called,
 * otherwise 'request_irq()' is used.
 *
 * Returns 0 on success, < 0 otherwise
 */
static __init int timer_of_irq_init(struct device_node *np,
                                    struct of_timer_irq *of_irq)
{
        int ret;
        struct timer_of *to = container_of(of_irq, struct timer_of, of_irq);
        struct clock_event_device *clkevt = &to->clkevt;

        if (of_irq->name) {
                of_irq->irq = ret = of_irq_get_byname(np, of_irq->name);
                if (ret < 0) {
                        pr_err("Failed to get interrupt %s for %s\n",
                               of_irq->name, np->full_name);
                        return ret;
                }
        } else  {
                of_irq->irq = irq_of_parse_and_map(np, of_irq->index);
        }
        if (!of_irq->irq) {
                pr_err("Failed to map interrupt for %pOF\n", np);
                return -EINVAL;
        }

        ret = of_irq->percpu ?
                request_percpu_irq(of_irq->irq, of_irq->handler,
                                   np->full_name, clkevt) :
                request_irq(of_irq->irq, of_irq->handler,
                            of_irq->flags ? of_irq->flags : IRQF_TIMER,
                            np->full_name, clkevt);
        if (ret) {
                pr_err("Failed to request irq %d for %pOF\n", of_irq->irq, np);
                return ret;
        }

        clkevt->irq = of_irq->irq;

        return 0;
}

/**
 * timer_of_clk_exit - Release the clock resources
 * @of_clk: a of_timer_clk structure pointer
 *
 * Disables and releases the refcount on the clk
 */
static __init void timer_of_clk_exit(struct of_timer_clk *of_clk)
{
        of_clk->rate = 0;
        clk_disable_unprepare(of_clk->clk);
        clk_put(of_clk->clk);
}

/**
 * timer_of_clk_init - Initialize the clock resources
 * @np: a device tree node pointer
 * @of_clk: a of_timer_clk structure pointer
 *
 * Get the clock by name or by index, enable it and get the rate
 *
 * Returns 0 on success, < 0 otherwise
 */
static __init int timer_of_clk_init(struct device_node *np,
                                    struct of_timer_clk *of_clk)
{
        int ret;

        of_clk->clk = of_clk->name ? of_clk_get_by_name(np, of_clk->name) :
                of_clk_get(np, of_clk->index);
        if (IS_ERR(of_clk->clk)) {
                pr_err("Failed to get clock for %pOF\n", np);
                return PTR_ERR(of_clk->clk);
        }

        ret = clk_prepare_enable(of_clk->clk);
        if (ret) {
                pr_err("Failed for enable clock for %pOF\n", np);
                goto out_clk_put;
        }

        of_clk->rate = clk_get_rate(of_clk->clk);
        if (!of_clk->rate) {
                ret = -EINVAL;
                pr_err("Failed to get clock rate for %pOF\n", np);
                goto out_clk_disable;
        }

        of_clk->period = DIV_ROUND_UP(of_clk->rate, HZ);
out:
        return ret;

out_clk_disable:
        clk_disable_unprepare(of_clk->clk);
out_clk_put:
        clk_put(of_clk->clk);

        goto out;
}

static __init void timer_of_base_exit(struct of_timer_base *of_base)
{
        iounmap(of_base->base);
}

static __init int timer_of_base_init(struct device_node *np,
                                     struct of_timer_base *of_base)
{
        of_base->base = of_base->name ?
                of_io_request_and_map(np, of_base->index, of_base->name) :
                of_iomap(np, of_base->index);
        if (IS_ERR(of_base->base)) {
                pr_err("Failed to iomap (%s)\n", of_base->name);
                return PTR_ERR(of_base->base);
        }

        return 0;
}

int __init timer_of_init(struct device_node *np, struct timer_of *to)
{
        int ret = -EINVAL;
        int flags = 0;

        if (to->flags & TIMER_OF_BASE) {
                ret = timer_of_base_init(np, &to->of_base);
                if (ret)
                        goto out_fail;
                flags |= TIMER_OF_BASE;
        }

        if (to->flags & TIMER_OF_CLOCK) {
                ret = timer_of_clk_init(np, &to->of_clk);
                if (ret)
                        goto out_fail;
                flags |= TIMER_OF_CLOCK;
        }

        if (to->flags & TIMER_OF_IRQ) {
                ret = timer_of_irq_init(np, &to->of_irq);
                if (ret)
                        goto out_fail;
                flags |= TIMER_OF_IRQ;
        }

        if (!to->clkevt.name)
                to->clkevt.name = np->name;

        to->np = np;

        return ret;

out_fail:
        if (flags & TIMER_OF_IRQ)
                timer_of_irq_exit(&to->of_irq);

        if (flags & TIMER_OF_CLOCK)
                timer_of_clk_exit(&to->of_clk);

        if (flags & TIMER_OF_BASE)
                timer_of_base_exit(&to->of_base);
        return ret;
}

/**
 * timer_of_cleanup - release timer_of ressources
 * @to: timer_of structure
 *
 * Release the ressources that has been used in timer_of_init().
 * This function should be called in init error cases
 */
void __init timer_of_cleanup(struct timer_of *to)
{
        if (to->flags & TIMER_OF_IRQ)
                timer_of_irq_exit(&to->of_irq);

        if (to->flags & TIMER_OF_CLOCK)
                timer_of_clk_exit(&to->of_clk);

        if (to->flags & TIMER_OF_BASE)
                timer_of_base_exit(&to->of_base);
}