sdio_irq.c

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/*
 * 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_host *host)
{
    struct mmc_card *card = host->card;
    int i, ret, count;
    unsigned char pending;
    struct sdio_func *func;

    /*
     * Optimization, if there is only 1 function interrupt registered
     * and we know an IRQ was signaled then call irq handler directly.
     * Otherwise do the full probe.
     */
    func = card->sdio_single_irq;
    if (func && host->sdio_irq_pending) {
        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);
        host->sdio_irq_pending = false;
        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;
               }
           }
}

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);

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);