gameport.c

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/*
 * Generic gameport layer
 *
 * Copyright (c) 1999-2002 Vojtech Pavlik
 * Copyright (c) 2005 Dmitry Torokhov
 */

/*
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/gameport.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/workqueue.h>
#include <linux/sched.h>    /* HZ */
#include <linux/mutex.h>

/*#include <asm/io.h>*/

MODULE_AUTHOR("Vojtech Pavlik <[email protected]>");
MODULE_DESCRIPTION("Generic gameport layer");
MODULE_LICENSE("GPL");

/*
 * gameport_mutex protects entire gameport subsystem and is taken
 * every time gameport port or driver registrered or unregistered.
 */
static DEFINE_MUTEX(gameport_mutex);

static LIST_HEAD(gameport_list);

static struct bus_type gameport_bus;

static void gameport_add_port(struct gameport *gameport);
static void gameport_attach_driver(struct gameport_driver *drv);
static void gameport_reconnect_port(struct gameport *gameport);
static void gameport_disconnect_port(struct gameport *gameport);

#if defined(__i386__)

#include <linux/i8253.h>

#define DELTA(x,y)      ((y)-(x)+((y)<(x)?1193182/HZ:0))
#define GET_TIME(x)     do { x = get_time_pit(); } while (0)

static unsigned int get_time_pit(void)
{
    unsigned long flags;
    unsigned int count;

    raw_spin_lock_irqsave(&i8253_lock, flags);
    outb_p(0x00, 0x43);
    count = inb_p(0x40);
    count |= inb_p(0x40) << 8;
    raw_spin_unlock_irqrestore(&i8253_lock, flags);

    return count;
}

#endif



/*
 * gameport_measure_speed() measures the gameport i/o speed.
 */

static int gameport_measure_speed(struct gameport *gameport)
{
#if defined(__i386__)

    unsigned int i, t, t1, t2, t3, tx;
    unsigned long flags;

    if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
        return 0;

    tx = 1 << 30;

    for(i = 0; i < 50; i++) {
        local_irq_save(flags);
        GET_TIME(t1);
        for (t = 0; t < 50; t++) gameport_read(gameport);
        GET_TIME(t2);
        GET_TIME(t3);
        local_irq_restore(flags);
        udelay(i * 10);
        if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
    }

    gameport_close(gameport);
    return 59659 / (tx < 1 ? 1 : tx);

#elif defined (__x86_64__)

    unsigned int i, t;
    unsigned long tx, t1, t2, flags;

    if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
        return 0;

    tx = 1 << 30;

    for(i = 0; i < 50; i++) {
        local_irq_save(flags);
        rdtscl(t1);
        for (t = 0; t < 50; t++) gameport_read(gameport);
        rdtscl(t2);
        local_irq_restore(flags);
        udelay(i * 10);
        if (t2 - t1 < tx) tx = t2 - t1;
    }

    gameport_close(gameport);
    return (this_cpu_read(cpu_info.loops_per_jiffy) *
        (unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);

#else

    unsigned int j, t = 0;

    if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
        return 0;

    j = jiffies; while (j == jiffies);
    j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }

    gameport_close(gameport);
    return t * HZ / 1000;

#endif
}

void gameport_start_polling(struct gameport *gameport)
{
    spin_lock(&gameport->timer_lock);

    if (!gameport->poll_cnt++) {
        BUG_ON(!gameport->poll_handler);
        BUG_ON(!gameport->poll_interval);
        mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
    }

    spin_unlock(&gameport->timer_lock);
}
EXPORT_SYMBOL(gameport_start_polling);

void gameport_stop_polling(struct gameport *gameport)
{
    spin_lock(&gameport->timer_lock);

    if (!--gameport->poll_cnt)
        del_timer(&gameport->poll_timer);

    spin_unlock(&gameport->timer_lock);
}
EXPORT_SYMBOL(gameport_stop_polling);

static void gameport_run_poll_handler(unsigned long d)
{
    struct gameport *gameport = (struct gameport *)d;

    gameport->poll_handler(gameport);
    if (gameport->poll_cnt)
        mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
}

/*
 * Basic gameport -> driver core mappings
 */

static int gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
{
    int error;

    gameport->dev.driver = &drv->driver;
    if (drv->connect(gameport, drv)) {
        gameport->dev.driver = NULL;
        return -ENODEV;
    }

    error = device_bind_driver(&gameport->dev);
    if (error) {
        dev_warn(&gameport->dev,
             "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
            gameport->phys, gameport->name,
            drv->description, error);
        drv->disconnect(gameport);
        gameport->dev.driver = NULL;
        return error;
    }

    return 0;
}

static void gameport_find_driver(struct gameport *gameport)
{
    int error;

    error = device_attach(&gameport->dev);
    if (error < 0)
        dev_warn(&gameport->dev,
             "device_attach() failed for %s (%s), error: %d\n",
             gameport->phys, gameport->name, error);
}


/*
 * Gameport event processing.
 */

enum gameport_event_type {
    GAMEPORT_REGISTER_PORT,
    GAMEPORT_ATTACH_DRIVER,
};

struct gameport_event {
    enum gameport_event_type type;
    void *object;
    struct module *owner;
    struct list_head node;
};

static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
static LIST_HEAD(gameport_event_list);

static struct gameport_event *gameport_get_event(void)
{
    struct gameport_event *event = NULL;
    unsigned long flags;

    spin_lock_irqsave(&gameport_event_lock, flags);

    if (!list_empty(&gameport_event_list)) {
        event = list_first_entry(&gameport_event_list,
                     struct gameport_event, node);
        list_del_init(&event->node);
    }

    spin_unlock_irqrestore(&gameport_event_lock, flags);
    return event;
}

static void gameport_free_event(struct gameport_event *event)
{
    module_put(event->owner);
    kfree(event);
}

static void gameport_remove_duplicate_events(struct gameport_event *event)
{
    struct gameport_event *e, *next;
    unsigned long flags;

    spin_lock_irqsave(&gameport_event_lock, flags);

    list_for_each_entry_safe(e, next, &gameport_event_list, node) {
        if (event->object == e->object) {
            /*
             * If this event is of different type we should not
             * look further - we only suppress duplicate events
             * that were sent back-to-back.
             */
            if (event->type != e->type)
                break;

            list_del_init(&e->node);
            gameport_free_event(e);
        }
    }

    spin_unlock_irqrestore(&gameport_event_lock, flags);
}


static void gameport_handle_events(struct work_struct *work)
{
    struct gameport_event *event;

    mutex_lock(&gameport_mutex);

    /*
     * Note that we handle only one event here to give swsusp
     * a chance to freeze kgameportd thread. Gameport events
     * should be pretty rare so we are not concerned about
     * taking performance hit.
     */
    if ((event = gameport_get_event())) {

        switch (event->type) {

        case GAMEPORT_REGISTER_PORT:
            gameport_add_port(event->object);
            break;

        case GAMEPORT_ATTACH_DRIVER:
            gameport_attach_driver(event->object);
            break;
        }

        gameport_remove_duplicate_events(event);
        gameport_free_event(event);
    }

    mutex_unlock(&gameport_mutex);
}

static DECLARE_WORK(gameport_event_work, gameport_handle_events);

static int gameport_queue_event(void *object, struct module *owner,
                enum gameport_event_type event_type)
{
    unsigned long flags;
    struct gameport_event *event;
    int retval = 0;

    spin_lock_irqsave(&gameport_event_lock, flags);

    /*
     * Scan event list for the other events for the same gameport port,
     * starting with the most recent one. If event is the same we
     * do not need add new one. If event is of different type we
     * need to add this event and should not look further because
     * we need to preserve sequence of distinct events.
     */
    list_for_each_entry_reverse(event, &gameport_event_list, node) {
        if (event->object == object) {
            if (event->type == event_type)
                goto out;
            break;
        }
    }

    event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
    if (!event) {
        pr_err("Not enough memory to queue event %d\n", event_type);
        retval = -ENOMEM;
        goto out;
    }

    if (!try_module_get(owner)) {
        pr_warning("Can't get module reference, dropping event %d\n",
               event_type);
        kfree(event);
        retval = -EINVAL;
        goto out;
    }

    event->type = event_type;
    event->object = object;
    event->owner = owner;

    list_add_tail(&event->node, &gameport_event_list);
    queue_work(system_long_wq, &gameport_event_work);

out:
    spin_unlock_irqrestore(&gameport_event_lock, flags);
    return retval;
}

/*
 * Remove all events that have been submitted for a given object,
 * be it a gameport port or a driver.
 */
static void gameport_remove_pending_events(void *object)
{
    struct gameport_event *event, *next;
    unsigned long flags;

    spin_lock_irqsave(&gameport_event_lock, flags);

    list_for_each_entry_safe(event, next, &gameport_event_list, node) {
        if (event->object == object) {
            list_del_init(&event->node);
            gameport_free_event(event);
        }
    }

    spin_unlock_irqrestore(&gameport_event_lock, flags);
}

/*
 * Destroy child gameport port (if any) that has not been fully registered yet.
 *
 * Note that we rely on the fact that port can have only one child and therefore
 * only one child registration request can be pending. Additionally, children
 * are registered by driver's connect() handler so there can't be a grandchild
 * pending registration together with a child.
 */
static struct gameport *gameport_get_pending_child(struct gameport *parent)
{
    struct gameport_event *event;
    struct gameport *gameport, *child = NULL;
    unsigned long flags;

    spin_lock_irqsave(&gameport_event_lock, flags);

    list_for_each_entry(event, &gameport_event_list, node) {
        if (event->type == GAMEPORT_REGISTER_PORT) {
            gameport = event->object;
            if (gameport->parent == parent) {
                child = gameport;
                break;
            }
        }
    }

    spin_unlock_irqrestore(&gameport_event_lock, flags);
    return child;
}

/*
 * Gameport port operations
 */

static ssize_t gameport_show_description(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct gameport *gameport = to_gameport_port(dev);

    return sprintf(buf, "%s\n", gameport->name);
}

static ssize_t gameport_rebind_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
    struct gameport *gameport = to_gameport_port(dev);
    struct device_driver *drv;
    int error;

    error = mutex_lock_interruptible(&gameport_mutex);
    if (error)
        return error;

    if (!strncmp(buf, "none", count)) {
        gameport_disconnect_port(gameport);
    } else if (!strncmp(buf, "reconnect", count)) {
        gameport_reconnect_port(gameport);
    } else if (!strncmp(buf, "rescan", count)) {
        gameport_disconnect_port(gameport);
        gameport_find_driver(gameport);
    } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
        gameport_disconnect_port(gameport);
        error = gameport_bind_driver(gameport, to_gameport_driver(drv));
    } else {
        error = -EINVAL;
    }

    mutex_unlock(&gameport_mutex);

    return error ? error : count;
}

static struct device_attribute gameport_device_attrs[] = {
    __ATTR(description, S_IRUGO, gameport_show_description, NULL),
    __ATTR(drvctl, S_IWUSR, NULL, gameport_rebind_driver),
    __ATTR_NULL
};

static void gameport_release_port(struct device *dev)
{
    struct gameport *gameport = to_gameport_port(dev);

    kfree(gameport);
    module_put(THIS_MODULE);
}

void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
    va_end(args);
}
EXPORT_SYMBOL(gameport_set_phys);

/*
 * Prepare gameport port for registration.
 */
static void gameport_init_port(struct gameport *gameport)
{
    static atomic_t gameport_no = ATOMIC_INIT(0);

    __module_get(THIS_MODULE);

    mutex_init(&gameport->drv_mutex);
    device_initialize(&gameport->dev);
    dev_set_name(&gameport->dev, "gameport%lu",
            (unsigned long)atomic_inc_return(&gameport_no) - 1);
    gameport->dev.bus = &gameport_bus;
    gameport->dev.release = gameport_release_port;
    if (gameport->parent)
        gameport->dev.parent = &gameport->parent->dev;

    INIT_LIST_HEAD(&gameport->node);
    spin_lock_init(&gameport->timer_lock);
    init_timer(&gameport->poll_timer);
    gameport->poll_timer.function = gameport_run_poll_handler;
    gameport->poll_timer.data = (unsigned long)gameport;
}

/*
 * Complete gameport port registration.
 * Driver core will attempt to find appropriate driver for the port.
 */
static void gameport_add_port(struct gameport *gameport)
{
    int error;

    if (gameport->parent)
        gameport->parent->child = gameport;

    gameport->speed = gameport_measure_speed(gameport);

    list_add_tail(&gameport->node, &gameport_list);

    if (gameport->io)
        dev_info(&gameport->dev, "%s is %s, io %#x, speed %dkHz\n",
             gameport->name, gameport->phys, gameport->io, gameport->speed);
    else
        dev_info(&gameport->dev, "%s is %s, speed %dkHz\n",
            gameport->name, gameport->phys, gameport->speed);

    error = device_add(&gameport->dev);
    if (error)
        dev_err(&gameport->dev,
            "device_add() failed for %s (%s), error: %d\n",
            gameport->phys, gameport->name, error);
}

/*
 * gameport_destroy_port() completes deregistration process and removes
 * port from the system
 */
static void gameport_destroy_port(struct gameport *gameport)
{
    struct gameport *child;

    child = gameport_get_pending_child(gameport);
    if (child) {
        gameport_remove_pending_events(child);
        put_device(&child->dev);
    }

    if (gameport->parent) {
        gameport->parent->child = NULL;
        gameport->parent = NULL;
    }

    if (device_is_registered(&gameport->dev))
        device_del(&gameport->dev);

    list_del_init(&gameport->node);

    gameport_remove_pending_events(gameport);
    put_device(&gameport->dev);
}

/*
 * Reconnect gameport port and all its children (re-initialize attached devices)
 */
static void gameport_reconnect_port(struct gameport *gameport)
{
    do {
        if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
            gameport_disconnect_port(gameport);
            gameport_find_driver(gameport);
            /* Ok, old children are now gone, we are done */
            break;
        }
        gameport = gameport->child;
    } while (gameport);
}

/*
 * gameport_disconnect_port() unbinds a port from its driver. As a side effect
 * all child ports are unbound and destroyed.
 */
static void gameport_disconnect_port(struct gameport *gameport)
{
    struct gameport *s, *parent;

    if (gameport->child) {
        /*
         * Children ports should be disconnected and destroyed
         * first, staring with the leaf one, since we don't want
         * to do recursion
         */
        for (s = gameport; s->child; s = s->child)
            /* empty */;

        do {
            parent = s->parent;

            device_release_driver(&s->dev);
            gameport_destroy_port(s);
        } while ((s = parent) != gameport);
    }

    /*
     * Ok, no children left, now disconnect this port
     */
    device_release_driver(&gameport->dev);
}

/*
 * Submits register request to kgameportd for subsequent execution.
 * Note that port registration is always asynchronous.
 */
void __gameport_register_port(struct gameport *gameport, struct module *owner)
{
    gameport_init_port(gameport);
    gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
}
EXPORT_SYMBOL(__gameport_register_port);

/*
 * Synchronously unregisters gameport port.
 */
void gameport_unregister_port(struct gameport *gameport)
{
    mutex_lock(&gameport_mutex);
    gameport_disconnect_port(gameport);
    gameport_destroy_port(gameport);
    mutex_unlock(&gameport_mutex);
}
EXPORT_SYMBOL(gameport_unregister_port);


/*
 * Gameport driver operations
 */

static ssize_t gameport_driver_show_description(struct device_driver *drv, char *buf)
{
    struct gameport_driver *driver = to_gameport_driver(drv);
    return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
}

static struct driver_attribute gameport_driver_attrs[] = {
    __ATTR(description, S_IRUGO, gameport_driver_show_description, NULL),
    __ATTR_NULL
};

static int gameport_driver_probe(struct device *dev)
{
    struct gameport *gameport = to_gameport_port(dev);
    struct gameport_driver *drv = to_gameport_driver(dev->driver);

    drv->connect(gameport, drv);
    return gameport->drv ? 0 : -ENODEV;
}

static int gameport_driver_remove(struct device *dev)
{
    struct gameport *gameport = to_gameport_port(dev);
    struct gameport_driver *drv = to_gameport_driver(dev->driver);

    drv->disconnect(gameport);
    return 0;
}

static void gameport_attach_driver(struct gameport_driver *drv)
{
    int error;

    error = driver_attach(&drv->driver);
    if (error)
        pr_err("driver_attach() failed for %s, error: %d\n",
            drv->driver.name, error);
}

int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
                const char *mod_name)
{
    int error;

    drv->driver.bus = &gameport_bus;
    drv->driver.owner = owner;
    drv->driver.mod_name = mod_name;

    /*
     * Temporarily disable automatic binding because probing
     * takes long time and we are better off doing it in kgameportd
     */
    drv->ignore = true;

    error = driver_register(&drv->driver);
    if (error) {
        pr_err("driver_register() failed for %s, error: %d\n",
            drv->driver.name, error);
        return error;
    }

    /*
     * Reset ignore flag and let kgameportd bind the driver to free ports
     */
    drv->ignore = false;
    error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
    if (error) {
        driver_unregister(&drv->driver);
        return error;
    }

    return 0;
}
EXPORT_SYMBOL(__gameport_register_driver);

void gameport_unregister_driver(struct gameport_driver *drv)
{
    struct gameport *gameport;

    mutex_lock(&gameport_mutex);

    drv->ignore = true; /* so gameport_find_driver ignores it */
    gameport_remove_pending_events(drv);

start_over:
    list_for_each_entry(gameport, &gameport_list, node) {
        if (gameport->drv == drv) {
            gameport_disconnect_port(gameport);
            gameport_find_driver(gameport);
            /* we could've deleted some ports, restart */
            goto start_over;
        }
    }

    driver_unregister(&drv->driver);

    mutex_unlock(&gameport_mutex);
}
EXPORT_SYMBOL(gameport_unregister_driver);

static int gameport_bus_match(struct device *dev, struct device_driver *drv)
{
    struct gameport_driver *gameport_drv = to_gameport_driver(drv);

    return !gameport_drv->ignore;
}

static struct bus_type gameport_bus = {
    .name       = "gameport",
    .dev_attrs  = gameport_device_attrs,
    .drv_attrs  = gameport_driver_attrs,
    .match      = gameport_bus_match,
    .probe      = gameport_driver_probe,
    .remove     = gameport_driver_remove,
};

static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
{
    mutex_lock(&gameport->drv_mutex);
    gameport->drv = drv;
    mutex_unlock(&gameport->drv_mutex);
}

int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
{
    if (gameport->open) {
        if (gameport->open(gameport, mode)) {
            return -1;
        }
    } else {
        if (mode != GAMEPORT_MODE_RAW)
            return -1;
    }

    gameport_set_drv(gameport, drv);
    return 0;
}
EXPORT_SYMBOL(gameport_open);

void gameport_close(struct gameport *gameport)
{
    del_timer_sync(&gameport->poll_timer);
    gameport->poll_handler = NULL;
    gameport->poll_interval = 0;
    gameport_set_drv(gameport, NULL);
    if (gameport->close)
        gameport->close(gameport);
}
EXPORT_SYMBOL(gameport_close);

static int __init gameport_init(void)
{
    int error;

    error = bus_register(&gameport_bus);
    if (error) {
        pr_err("failed to register gameport bus, error: %d\n", error);
        return error;
    }


    return 0;
}

static void __exit gameport_exit(void)
{
    bus_unregister(&gameport_bus);

    /*
     * There should not be any outstanding events but work may
     * still be scheduled so simply cancel it.
     */
    cancel_work_sync(&gameport_event_work);
}

subsys_initcall(gameport_init);
module_exit(gameport_exit);