videocodec.c

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/*
 * VIDEO MOTION CODECs internal API for video devices
 *
 * Interface for MJPEG (and maybe later MPEG/WAVELETS) codec's
 * bound to a master device.
 *
 * (c) 2002 Wolfgang Scherr <[email protected]>
 *
 * $Id: videocodec.c,v 1.1.2.8 2003/03/29 07:16:04 rbultje Exp $
 *
 * ------------------------------------------------------------------------
 *
 * 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.
 *
 * This program is distributed in the hope that 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, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * ------------------------------------------------------------------------
 */

#define VIDEOCODEC_VERSION "v0.2"

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>

// kernel config is here (procfs flag)

#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/uaccess.h>
#endif

#include "videocodec.h"

static int debug;
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug level (0-4)");

#define dprintk(num, format, args...) \
    do { \
        if (debug >= num) \
            printk(format, ##args); \
    } while (0)

struct attached_list {
    struct videocodec *codec;
    struct attached_list *next;
};

struct codec_list {
    const struct videocodec *codec;
    int attached;
    struct attached_list *list;
    struct codec_list *next;
};

static struct codec_list *codeclist_top = NULL;

/* ================================================= */
/* function prototypes of the master/slave interface */
/* ================================================= */

struct videocodec *
videocodec_attach (struct videocodec_master *master)
{
    struct codec_list *h = codeclist_top;
    struct attached_list *a, *ptr;
    struct videocodec *codec;
    int res;

    if (!master) {
        dprintk(1, KERN_ERR "videocodec_attach: no data\n");
        return NULL;
    }

    dprintk(2,
        "videocodec_attach: '%s', flags %lx, magic %lx\n",
        master->name, master->flags, master->magic);

    if (!h) {
        dprintk(1,
            KERN_ERR
            "videocodec_attach: no device available\n");
        return NULL;
    }

    while (h) {
        // attach only if the slave has at least the flags
        // expected by the master
        if ((master->flags & h->codec->flags) == master->flags) {
            dprintk(4, "videocodec_attach: try '%s'\n",
                h->codec->name);

            if (!try_module_get(h->codec->owner))
                return NULL;

            codec = kmemdup(h->codec, sizeof(struct videocodec),
                    GFP_KERNEL);
            if (!codec) {
                dprintk(1,
                    KERN_ERR
                    "videocodec_attach: no mem\n");
                goto out_module_put;
            }

            snprintf(codec->name, sizeof(codec->name),
                 "%s[%d]", codec->name, h->attached);
            codec->master_data = master;
            res = codec->setup(codec);
            if (res == 0) {
                dprintk(3, "videocodec_attach '%s'\n",
                    codec->name);
                ptr = kzalloc(sizeof(struct attached_list), GFP_KERNEL);
                if (!ptr) {
                    dprintk(1,
                        KERN_ERR
                        "videocodec_attach: no memory\n");
                    goto out_kfree;
                }
                ptr->codec = codec;

                a = h->list;
                if (!a) {
                    h->list = ptr;
                    dprintk(4,
                        "videocodec: first element\n");
                } else {
                    while (a->next)
                        a = a->next;    // find end
                    a->next = ptr;
                    dprintk(4,
                        "videocodec: in after '%s'\n",
                        h->codec->name);
                }

                h->attached += 1;
                return codec;
            } else {
                kfree(codec);
            }
        }
        h = h->next;
    }

    dprintk(1, KERN_ERR "videocodec_attach: no codec found!\n");
    return NULL;

 out_module_put:
    module_put(h->codec->owner);
 out_kfree:
    kfree(codec);
    return NULL;
}

int
videocodec_detach (struct videocodec *codec)
{
    struct codec_list *h = codeclist_top;
    struct attached_list *a, *prev;
    int res;

    if (!codec) {
        dprintk(1, KERN_ERR "videocodec_detach: no data\n");
        return -EINVAL;
    }

    dprintk(2,
        "videocodec_detach: '%s', type: %x, flags %lx, magic %lx\n",
        codec->name, codec->type, codec->flags, codec->magic);

    if (!h) {
        dprintk(1,
            KERN_ERR "videocodec_detach: no device left...\n");
        return -ENXIO;
    }

    while (h) {
        a = h->list;
        prev = NULL;
        while (a) {
            if (codec == a->codec) {
                res = a->codec->unset(a->codec);
                if (res >= 0) {
                    dprintk(3,
                        "videocodec_detach: '%s'\n",
                        a->codec->name);
                    a->codec->master_data = NULL;
                } else {
                    dprintk(1,
                        KERN_ERR
                        "videocodec_detach: '%s'\n",
                        a->codec->name);
                    a->codec->master_data = NULL;
                }
                if (prev == NULL) {
                    h->list = a->next;
                    dprintk(4,
                        "videocodec: delete first\n");
                } else {
                    prev->next = a->next;
                    dprintk(4,
                        "videocodec: delete middle\n");
                }
                module_put(a->codec->owner);
                kfree(a->codec);
                kfree(a);
                h->attached -= 1;
                return 0;
            }
            prev = a;
            a = a->next;
        }
        h = h->next;
    }

    dprintk(1, KERN_ERR "videocodec_detach: given codec not found!\n");
    return -EINVAL;
}

int
videocodec_register (const struct videocodec *codec)
{
    struct codec_list *ptr, *h = codeclist_top;

    if (!codec) {
        dprintk(1, KERN_ERR "videocodec_register: no data!\n");
        return -EINVAL;
    }

    dprintk(2,
        "videocodec: register '%s', type: %x, flags %lx, magic %lx\n",
        codec->name, codec->type, codec->flags, codec->magic);

    ptr = kzalloc(sizeof(struct codec_list), GFP_KERNEL);
    if (!ptr) {
        dprintk(1, KERN_ERR "videocodec_register: no memory\n");
        return -ENOMEM;
    }
    ptr->codec = codec;

    if (!h) {
        codeclist_top = ptr;
        dprintk(4, "videocodec: hooked in as first element\n");
    } else {
        while (h->next)
            h = h->next;    // find the end
        h->next = ptr;
        dprintk(4, "videocodec: hooked in after '%s'\n",
            h->codec->name);
    }

    return 0;
}

int
videocodec_unregister (const struct videocodec *codec)
{
    struct codec_list *prev = NULL, *h = codeclist_top;

    if (!codec) {
        dprintk(1, KERN_ERR "videocodec_unregister: no data!\n");
        return -EINVAL;
    }

    dprintk(2,
        "videocodec: unregister '%s', type: %x, flags %lx, magic %lx\n",
        codec->name, codec->type, codec->flags, codec->magic);

    if (!h) {
        dprintk(1,
            KERN_ERR
            "videocodec_unregister: no device left...\n");
        return -ENXIO;
    }

    while (h) {
        if (codec == h->codec) {
            if (h->attached) {
                dprintk(1,
                    KERN_ERR
                    "videocodec: '%s' is used\n",
                    h->codec->name);
                return -EBUSY;
            }
            dprintk(3, "videocodec: unregister '%s' is ok.\n",
                h->codec->name);
            if (prev == NULL) {
                codeclist_top = h->next;
                dprintk(4,
                    "videocodec: delete first element\n");
            } else {
                prev->next = h->next;
                dprintk(4,
                    "videocodec: delete middle element\n");
            }
            kfree(h);
            return 0;
        }
        prev = h;
        h = h->next;
    }

    dprintk(1,
        KERN_ERR
        "videocodec_unregister: given codec not found!\n");
    return -EINVAL;
}

#ifdef CONFIG_PROC_FS
static int proc_videocodecs_show(struct seq_file *m, void *v)
{
    struct codec_list *h = codeclist_top;
    struct attached_list *a;

    seq_printf(m, "<S>lave or attached <M>aster name  type flags    magic    ");
    seq_printf(m, "(connected as)\n");

    h = codeclist_top;
    while (h) {
        seq_printf(m, "S %32s %04x %08lx %08lx (TEMPLATE)\n",
                  h->codec->name, h->codec->type,
                  h->codec->flags, h->codec->magic);
        a = h->list;
        while (a) {
            seq_printf(m, "M %32s %04x %08lx %08lx (%s)\n",
                      a->codec->master_data->name,
                      a->codec->master_data->type,
                      a->codec->master_data->flags,
                      a->codec->master_data->magic,
                      a->codec->name);
            a = a->next;
        }
        h = h->next;
    }

    return 0;
}

static int proc_videocodecs_open(struct inode *inode, struct file *file)
{
    return single_open(file, proc_videocodecs_show, NULL);
}

static const struct file_operations videocodecs_proc_fops = {
    .owner      = THIS_MODULE,
    .open       = proc_videocodecs_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};
#endif

/* ===================== */
/* hook in driver module */
/* ===================== */
static int __init
videocodec_init (void)
{
#ifdef CONFIG_PROC_FS
    static struct proc_dir_entry *videocodec_proc_entry;
#endif

    printk(KERN_INFO "Linux video codec intermediate layer: %s\n",
           VIDEOCODEC_VERSION);

#ifdef CONFIG_PROC_FS
    videocodec_proc_entry = proc_create("videocodecs", 0, NULL, &videocodecs_proc_fops);
    if (!videocodec_proc_entry) {
        dprintk(1, KERN_ERR "videocodec: can't init procfs.\n");
    }
#endif
    return 0;
}

static void __exit
videocodec_exit (void)
{
#ifdef CONFIG_PROC_FS
    remove_proc_entry("videocodecs", NULL);
#endif
}

EXPORT_SYMBOL(videocodec_attach);
EXPORT_SYMBOL(videocodec_detach);
EXPORT_SYMBOL(videocodec_register);
EXPORT_SYMBOL(videocodec_unregister);

module_init(videocodec_init);
module_exit(videocodec_exit);

MODULE_AUTHOR("Wolfgang Scherr <[email protected]>");
MODULE_DESCRIPTION("Intermediate API module for video codecs "
           VIDEOCODEC_VERSION);
MODULE_LICENSE("GPL");