/*
 * linux/drivers/mmc/core/sdio_irq.c
 *
 * Author:      Nicolas Pitre
 * Created:     June 18, 2007
 * Copyright:   MontaVista Software Inc.
 *
 * Copyright 2008 Pierre Ossman
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/kthread.h>
#include <linux/export.h>
#include <linux/wait.h>
#include <linux/delay.h>

#include <linux/mmc/core.h>
#include <linux/mmc/host.h>
#include <linux/mmc/card.h>
#include <linux/mmc/sdio.h>
#include <linux/mmc/sdio_func.h>

#include "sdio_ops.h"

static int process_sdio_pending_irqs(struct mmc_card *card)
{
        int i, ret, count;
        unsigned char pending;
        struct sdio_func *func;

        /*
         * Optimization, if there is only 1 function interrupt registered
         * call irq handler directly
         */
        func = card->sdio_single_irq;
        if (func) {
                func->irq_handler(func);
                return 1;
        }

        ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_INTx, 0, &pending);
        if (ret) {
                pr_debug("%s: error %d reading SDIO_CCCR_INTx\n",
                       mmc_card_id(card), ret);
                return ret;
        }

        count = 0;
        for (i = 1; i <= 7; i++) {
                if (pending & (1 << i)) {
                        func = card->sdio_func[i - 1];
                        if (!func) {
                                pr_warning("%s: pending IRQ for "
                                        "non-existent function\n",
                                        mmc_card_id(card));
                                ret = -EINVAL;
                        } else if (func->irq_handler) {
                                func->irq_handler(func);
                                count++;
                        } else {
                                pr_warning("%s: pending IRQ with no handler\n",
                                       sdio_func_id(func));
                                ret = -EINVAL;
                        }
                }
        }

        if (count)
                return count;

        return ret;
}

static int sdio_irq_thread(void *_host)
{
        struct mmc_host *host = _host;
        struct sched_param param = { .sched_priority = 1 };
        unsigned long period, idle_period;
        int ret;

        sched_setscheduler(current, SCHED_FIFO, &param);

        /*
         * We want to allow for SDIO cards to work even on non SDIO
         * aware hosts.  One thing that non SDIO host cannot do is
         * asynchronous notification of pending SDIO card interrupts
         * hence we poll for them in that case.
         */
        idle_period = msecs_to_jiffies(10);
        period = (host->caps & MMC_CAP_SDIO_IRQ) ?
                MAX_SCHEDULE_TIMEOUT : idle_period;

        pr_debug("%s: IRQ thread started (poll period = %lu jiffies)\n",
                 mmc_hostname(host), period);

        do {
                /*
                 * We claim the host here on drivers behalf for a couple
                 * reasons:
                 *
                 * 1) it is already needed to retrieve the CCCR_INTx;
                 * 2) we want the driver(s) to clear the IRQ condition ASAP;
                 * 3) we need to control the abort condition locally.
                 *
                 * Just like traditional hard IRQ handlers, we expect SDIO
                 * IRQ handlers to be quick and to the point, so that the
                 * holding of the host lock does not cover too much work
                 * that doesn't require that lock to be held.
                 */
                ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort);
                if (ret)
                        break;
                ret = process_sdio_pending_irqs(host->card);
                mmc_release_host(host);

                /*
                 * Give other threads a chance to run in the presence of
                 * errors.
                 */
                if (ret < 0) {
                        set_current_state(TASK_INTERRUPTIBLE);
                        if (!kthread_should_stop())
                                schedule_timeout(HZ);
                        set_current_state(TASK_RUNNING);
                }

                /*
                 * Adaptive polling frequency based on the assumption
                 * that an interrupt will be closely followed by more.
                 * This has a substantial benefit for network devices.
                 */
                if (!(host->caps & MMC_CAP_SDIO_IRQ)) {
                        if (ret > 0)
                                period /= 2;
                        else {
                                period++;
                                if (period > idle_period)
                                        period = idle_period;
                        }
                }

                set_current_state(TASK_INTERRUPTIBLE);
                if (host->caps & MMC_CAP_SDIO_IRQ) {
                        mmc_host_clk_hold(host);
                        host->ops->enable_sdio_irq(host, 1);
                        mmc_host_clk_release(host);
                }
                if (!kthread_should_stop())
                        schedule_timeout(period);
                set_current_state(TASK_RUNNING);
        } while (!kthread_should_stop());

        if (host->caps & MMC_CAP_SDIO_IRQ) {
                mmc_host_clk_hold(host);
                host->ops->enable_sdio_irq(host, 0);
                mmc_host_clk_release(host);
        }

        pr_debug("%s: IRQ thread exiting with code %d\n",
                 mmc_hostname(host), ret);

        return ret;
}

static int sdio_card_irq_get(struct mmc_card *card)
{
        struct mmc_host *host = card->host;

        WARN_ON(!host->claimed);

        if (!host->sdio_irqs++) {
                atomic_set(&host->sdio_irq_thread_abort, 0);
                host->sdio_irq_thread =
                        kthread_run(sdio_irq_thread, host, "ksdioirqd/%s",
                                mmc_hostname(host));
                if (IS_ERR(host->sdio_irq_thread)) {
                        int err = PTR_ERR(host->sdio_irq_thread);
                        host->sdio_irqs--;
                        return err;
                }
        }

        return 0;
}

static int sdio_card_irq_put(struct mmc_card *card)
{
        struct mmc_host *host = card->host;

        WARN_ON(!host->claimed);
        BUG_ON(host->sdio_irqs < 1);

        if (!--host->sdio_irqs) {
                atomic_set(&host->sdio_irq_thread_abort, 1);
                kthread_stop(host->sdio_irq_thread);
        }

        return 0;
}

/* If there is only 1 function registered set sdio_single_irq */
static void sdio_single_irq_set(struct mmc_card *card)
{
        struct sdio_func *func;
        int i;

        card->sdio_single_irq = NULL;
        if ((card->host->caps & MMC_CAP_SDIO_IRQ) &&
            card->host->sdio_irqs == 1)
                for (i = 0; i < card->sdio_funcs; i++) {
                       func = card->sdio_func[i];
                       if (func && func->irq_handler) {
                               card->sdio_single_irq = func;
                               break;
                       }
               }
}

/**
 *      sdio_claim_irq - claim the IRQ for a SDIO function
 *      @func: SDIO function
 *      @handler: IRQ handler callback
 *
 *      Claim and activate the IRQ for the given SDIO function. The provided
 *      handler will be called when that IRQ is asserted.  The host is always
 *      claimed already when the handler is called so the handler must not
 *      call sdio_claim_host() nor sdio_release_host().
 */
int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler)
{
        int ret;
        unsigned char reg;

        BUG_ON(!func);
        BUG_ON(!func->card);

        pr_debug("SDIO: Enabling IRQ for %s...\n", sdio_func_id(func));

        if (func->irq_handler) {
                pr_debug("SDIO: IRQ for %s already in use.\n", sdio_func_id(func));
                return -EBUSY;
        }

        ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
        if (ret)
                return ret;

        reg |= 1 << func->num;

        reg |= 1; /* Master interrupt enable */

        ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IENx, reg, NULL);
        if (ret)
                return ret;

        func->irq_handler = handler;
        ret = sdio_card_irq_get(func->card);
        if (ret)
                func->irq_handler = NULL;
        sdio_single_irq_set(func->card);

        return ret;
}
EXPORT_SYMBOL_GPL(sdio_claim_irq);

/**
 *      sdio_release_irq - release the IRQ for a SDIO function
 *      @func: SDIO function
 *
 *      Disable and release the IRQ for the given SDIO function.
 */
int sdio_release_irq(struct sdio_func *func)
{
        int ret;
        unsigned char reg;

        BUG_ON(!func);
        BUG_ON(!func->card);

        pr_debug("SDIO: Disabling IRQ for %s...\n", sdio_func_id(func));

        if (func->irq_handler) {
                func->irq_handler = NULL;
                sdio_card_irq_put(func->card);
                sdio_single_irq_set(func->card);
        }

        ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
        if (ret)
                return ret;

        reg &= ~(1 << func->num);

        /* Disable master interrupt with the last function interrupt */
        if (!(reg & 0xFE))
                reg = 0;

        ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IENx, reg, NULL);
        if (ret)
                return ret;

        return 0;
}
EXPORT_SYMBOL_GPL(sdio_release_irq);