/*
 *  arch/s390/kernel/debug.c
 *   S/390 debug facility
 *
 *    Copyright (C) 1999, 2000 IBM Deutschland Entwicklung GmbH,
 *                             IBM Corporation
 *    Author(s): Michael Holzheu (holzheu@de.ibm.com),
 *               Holger Smolinski (Holger.Smolinski@de.ibm.com)
 *
 *    Bugreports to: <Linux390@de.ibm.com>
 */

#include <linux/config.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/version.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>

#include <linux/module.h>

#include <asm/debug.h>

#define MIN(a,b) (((a)<(b))?(a):(b))
#define DEBUG_PROLOG_ENTRY -1

/* typedefs */

typedef struct file_private_info {
        loff_t offset;                  /* offset of last read in file */
        int    act_area;                /* number of last formated area */
        int    act_entry;               /* last formated entry (offset */
                                        /* relative to beginning of last */
                                        /* formated area) */ 
        size_t act_entry_offset;        /* up to this offset we copied */
                                        /* in last read the last formated */
                                        /* entry to userland */
        char   temp_buf[2048];          /* buffer for output */
        debug_info_t *debug_info_org;   /* original debug information */
        debug_info_t *debug_info_snap;  /* snapshot of debug information */
        struct debug_view *view;        /* used view of debug info */
} file_private_info_t;

typedef struct
{
        char *string;
        /* 
         * This assumes that all args are converted into longs 
         * on L/390 this is the case for all types of parameter 
         * except of floats, and long long (32 bit) 
         *
         */
        long args[0];
} debug_sprintf_entry;


extern void tod_to_timeval(uint64_t todval, struct timeval *xtime);

/* internal function prototyes */

static int debug_init(void);
static ssize_t debug_output(struct file *file, char *user_buf,
                            size_t user_len, loff_t * offset);
static ssize_t debug_input(struct file *file, const char *user_buf,
                           size_t user_len, loff_t * offset);
static int debug_open(struct inode *inode, struct file *file);
static int debug_close(struct inode *inode, struct file *file);
static struct proc_dir_entry 
*debug_create_proc_dir_entry(struct proc_dir_entry *root,
                             const char *name, mode_t mode,
                             struct inode_operations *iops,
                             struct file_operations *fops);
static void debug_delete_proc_dir_entry(struct proc_dir_entry *root,
                                        struct proc_dir_entry *entry);
static debug_info_t*  debug_info_create(char *name, int page_order, int nr_areas, int buf_size);
static void debug_info_get(debug_info_t *);
static void debug_info_put(debug_info_t *);
static int debug_prolog_level_fn(debug_info_t * id,
                                 struct debug_view *view, char *out_buf);
static int debug_input_level_fn(debug_info_t * id, struct debug_view *view,
                                struct file *file, const char *user_buf,
                                size_t user_buf_size, loff_t * offset);
static int debug_input_flush_fn(debug_info_t * id, struct debug_view *view,
                                struct file *file, const char *user_buf,
                                size_t user_buf_size, loff_t * offset);
static int debug_hex_ascii_format_fn(debug_info_t * id, struct debug_view *view,
                                char *out_buf, const char *in_buf);
static int debug_raw_format_fn(debug_info_t * id,
                                 struct debug_view *view, char *out_buf,
                                 const char *in_buf);
static int debug_raw_header_fn(debug_info_t * id, struct debug_view *view,
                         int area, debug_entry_t * entry, char *out_buf);

static int debug_sprintf_format_fn(debug_info_t * id, struct debug_view *view,
                                   char *out_buf, debug_sprintf_entry *curr_event);

/* globals */

struct debug_view debug_raw_view = {
        "raw",
        NULL,
        &debug_raw_header_fn,
        &debug_raw_format_fn,
        NULL,
        NULL
};

struct debug_view debug_hex_ascii_view = {
        "hex_ascii",
        NULL,
        &debug_dflt_header_fn,
        &debug_hex_ascii_format_fn,
        NULL,
        NULL
};

struct debug_view debug_level_view = {
        "level",
        &debug_prolog_level_fn,
        NULL,
        NULL,
        &debug_input_level_fn,
        NULL
};

struct debug_view debug_flush_view = {
        "flush",
        NULL,
        NULL,
        NULL,
        &debug_input_flush_fn,
        NULL
};

struct debug_view debug_sprintf_view = {
        "sprintf",
        NULL,
        &debug_dflt_header_fn,
        (debug_format_proc_t*)&debug_sprintf_format_fn,
        NULL,
        NULL
};


unsigned int debug_feature_version = __DEBUG_FEATURE_VERSION;

/* static globals */

static debug_info_t *debug_area_first = NULL;
static debug_info_t *debug_area_last = NULL;
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,3,98))
static struct semaphore debug_lock = MUTEX;
#else
DECLARE_MUTEX(debug_lock);
#endif

static int initialized = 0;

static struct file_operations debug_file_ops = {
        read:    debug_output,
        write:   debug_input,   
        open:    debug_open,
        release: debug_close,
};

static struct inode_operations debug_inode_ops = {
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,3,98))
        default_file_ops: &debug_file_ops,      /* file ops */
#endif
};


static struct proc_dir_entry *debug_proc_root_entry;

/* functions */

/*
 * debug_info_alloc
 * - alloc new debug-info
 */

static debug_info_t*  debug_info_alloc(char *name, int page_order,
                                        int nr_areas, int buf_size)
{
        debug_info_t* rc;
        int i;

        /* alloc everything */

        rc = (debug_info_t*) kmalloc(sizeof(debug_info_t), GFP_ATOMIC);
        if(!rc)
                goto fail_malloc_rc;
        rc->active_entry = (int*)kmalloc(nr_areas * sizeof(int), GFP_ATOMIC);
        if(!rc->active_entry)
                goto fail_malloc_active_entry;
        memset(rc->active_entry, 0, nr_areas * sizeof(int));
        rc->areas = (debug_entry_t **) kmalloc(nr_areas *
                                                sizeof(debug_entry_t *),
                                                GFP_ATOMIC);
        if (!rc->areas)
                goto fail_malloc_areas;
        for (i = 0; i < nr_areas; i++) {
                rc->areas[i] = (debug_entry_t *) __get_free_pages(GFP_ATOMIC,
                                                                page_order);
                if (!rc->areas[i]) {
                        for (i--; i >= 0; i--) {
                                free_pages((unsigned long) rc->areas[i],
                                                page_order);
                        }
                        goto fail_malloc_areas2;
                } else {
                        memset(rc->areas[i], 0, PAGE_SIZE << page_order);
                }
        }

        /* initialize members */

        spin_lock_init(&rc->lock);
        rc->page_order  = page_order;
        rc->nr_areas    = nr_areas;
        rc->active_area = 0;
        rc->level       = DEBUG_DEFAULT_LEVEL;
        rc->buf_size    = buf_size;
        rc->entry_size  = sizeof(debug_entry_t) + buf_size;
        strncpy(rc->name, name, MIN(strlen(name), (DEBUG_MAX_PROCF_LEN - 1)));
        rc->name[MIN(strlen(name), (DEBUG_MAX_PROCF_LEN - 1))] = 0;
        memset(rc->views, 0, DEBUG_MAX_VIEWS * sizeof(struct debug_view *));
#ifdef CONFIG_PROC_FS
        memset(rc->proc_entries, 0 ,DEBUG_MAX_VIEWS *
                sizeof(struct proc_dir_entry*));
#endif /* CONFIG_PROC_FS */
        atomic_set(&(rc->ref_count), 0);

        return rc;

fail_malloc_areas2:
        kfree(rc->areas);
fail_malloc_areas:
        kfree(rc->active_entry);
fail_malloc_active_entry:
        kfree(rc);
fail_malloc_rc:
        return NULL;
}

/*
 * debug_info_free
 * - free memory debug-info
 */

static void debug_info_free(debug_info_t* db_info){
        int i;
        for (i = 0; i < db_info->nr_areas; i++) {
                free_pages((unsigned long) db_info->areas[i],
                db_info->page_order);
        }
        kfree(db_info->areas);
        kfree(db_info->active_entry);
        kfree(db_info);
}

/*
 * debug_info_create
 * - create new debug-info
 */

static debug_info_t*  debug_info_create(char *name, int page_order, 
                                        int nr_areas, int buf_size)
{
        debug_info_t* rc;

        rc = debug_info_alloc(name, page_order, nr_areas, buf_size);
        if(!rc) 
                goto out;


        /* create proc rood directory */

        rc->proc_root_entry =
            debug_create_proc_dir_entry(debug_proc_root_entry, rc->name,
                                        S_IFDIR | S_IRUGO | S_IXUGO |
                                        S_IWUSR | S_IWGRP, NULL, NULL);

        /* append new element to linked list */

        if(debug_area_first == NULL){
                /* first element in list */
                debug_area_first = rc;
                rc->prev = NULL;
        }
        else{
                /* append element to end of list */
                debug_area_last->next = rc;
                rc->prev = debug_area_last;
        }
        debug_area_last = rc;
        rc->next = NULL;

        debug_info_get(rc);
out:
        return rc;
}

/*
 * debug_info_copy
 * - copy debug-info
 */

static debug_info_t* debug_info_copy(debug_info_t* in)
{
        int i;
        debug_info_t* rc;
        rc = debug_info_alloc(in->name, in->page_order, 
                                in->nr_areas, in->buf_size);
        if(!rc)
                goto out;

        for(i = 0; i < in->nr_areas; i++){
                memcpy(rc->areas[i],in->areas[i], PAGE_SIZE << in->page_order);
        }
out:
        return rc;
}

/*
 * debug_info_get
 * - increments reference count for debug-info
 */

static void debug_info_get(debug_info_t * db_info)
{
        if (db_info)
                atomic_inc(&db_info->ref_count);
}

/*
 * debug_info_put:
 * - decreases reference count for debug-info and frees it if necessary
 */

static void debug_info_put(debug_info_t *db_info)
{
        int i;

        if (!db_info)
                return;
        if (atomic_dec_and_test(&db_info->ref_count)) {
#ifdef DEBUG
                printk(KERN_INFO "debug: freeing debug area %p (%s)\n",
                       db_info, db_info->name);
#endif
                for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
                        if (db_info->views[i] != NULL)
                                debug_delete_proc_dir_entry
                                    (db_info->proc_root_entry,
                                     db_info->proc_entries[i]);
                }
                debug_delete_proc_dir_entry(debug_proc_root_entry,
                                            db_info->proc_root_entry);
                if(db_info == debug_area_first)
                        debug_area_first = db_info->next;
                if(db_info == debug_area_last)
                        debug_area_last = db_info->prev;
                if(db_info->prev) db_info->prev->next = db_info->next;
                if(db_info->next) db_info->next->prev = db_info->prev;
                debug_info_free(db_info);
        }
}

/*
 * debug_format_entry:
 * - format one debug entry and return size of formated data
 */

static int debug_format_entry(file_private_info_t *p_info)
{
        debug_info_t *id_org    = p_info->debug_info_org;
        debug_info_t *id_snap   = p_info->debug_info_snap;
        struct debug_view *view = p_info->view;
        debug_entry_t *act_entry;
        size_t len = 0;
        if(p_info->act_entry == DEBUG_PROLOG_ENTRY){
                /* print prolog */
                if (view->prolog_proc)
                        len += view->prolog_proc(id_org, view,p_info->temp_buf);
                goto out;
        }

        act_entry = (debug_entry_t *) ((char*)id_snap->areas[p_info->act_area] +
                                        p_info->act_entry);
                        
        if (act_entry->id.stck == 0LL)
                        goto out;  /* empty entry */
        if (view->header_proc)
                len += view->header_proc(id_org, view, p_info->act_area, 
                                        act_entry, p_info->temp_buf + len);
        if (view->format_proc)
                len += view->format_proc(id_org, view, p_info->temp_buf + len,
                                                DEBUG_DATA(act_entry));
      out:
        return len;
}

/*
 * debug_next_entry:
 * - goto next entry in p_info
 */

extern inline int debug_next_entry(file_private_info_t *p_info)
{
        debug_info_t *id = p_info->debug_info_snap;
        if(p_info->act_entry == DEBUG_PROLOG_ENTRY){
                p_info->act_entry = 0;
                goto out;
        }
        if ((p_info->act_entry += id->entry_size)
                > ((PAGE_SIZE << (id->page_order)) 
                - id->entry_size)){

                /* next area */
                p_info->act_entry = 0;
                p_info->act_area++;
                if(p_info->act_area >= id->nr_areas)
                        return 1;
        }
out:
        return 0;       
}

/*
 * debug_output:
 * - called for user read()
 * - copies formated debug entries to the user buffer
 */

static ssize_t debug_output(struct file *file,  /* file descriptor */
                            char *user_buf,     /* user buffer */
                            size_t  len,        /* length of buffer */
                            loff_t *offset      /* offset in the file */ )
{
        size_t count = 0;
        size_t entry_offset, size = 0;
        int rc;
        file_private_info_t *p_info;

        p_info = ((file_private_info_t *) file->private_data);
        if (*offset != p_info->offset) 
                return -EPIPE;
        if(p_info->act_area >= p_info->debug_info_snap->nr_areas)
                return 0;

        entry_offset = p_info->act_entry_offset;

        while(count < len){
                size = debug_format_entry(p_info);
                size = MIN((len - count), (size - entry_offset));

                if(size){
                        if (copy_to_user(user_buf + count, 
                                        p_info->temp_buf + entry_offset, size))
                                return -EFAULT;
                }
                count += size;
                entry_offset = 0;
                if(count != len)
                        if(debug_next_entry(p_info)) 
                                goto out;
        }
out:
        p_info->offset           += count;
        p_info->act_entry_offset = size;        
        *offset = p_info->offset;
        return count;
}

/*
 * debug_input:
 * - called for user write()
 * - calls input function of view
 */

static ssize_t debug_input(struct file *file,
                           const char *user_buf, size_t length,
                           loff_t *offset)
{
        int rc = 0;
        file_private_info_t *p_info;

        down(&debug_lock);
        p_info = ((file_private_info_t *) file->private_data);
        if (p_info->view->input_proc)
                rc = p_info->view->input_proc(p_info->debug_info_org,
                                              p_info->view, file, user_buf,
                                              length, offset);
        else
                rc = -EPERM;
        up(&debug_lock);
        return rc;              /* number of input characters */
}

/*
 * debug_open:
 * - called for user open()
 * - copies formated output to private_data area of the file
 *   handle
 */

static int debug_open(struct inode *inode, struct file *file)
{
        int i = 0, rc = 0;
        file_private_info_t *p_info;
        debug_info_t *debug_info, *debug_info_snapshot;

#ifdef DEBUG
        printk("debug_open\n");
#endif
        MOD_INC_USE_COUNT;
        down(&debug_lock);

        /* find debug log and view */

        debug_info = debug_area_first;
        while(debug_info != NULL){
                for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
                        if (debug_info->views[i] == NULL)
                                continue;
                        else if (debug_info->proc_entries[i]->low_ino ==
                                 file->f_dentry->d_inode->i_ino) {
                                goto found;     /* found view ! */
                        }
                }
                debug_info = debug_info->next;
        }
        /* no entry found */
        rc = -EINVAL;
        goto out;

      found:

        /* make snapshot of current debug areas to get it consistent */

        debug_info_snapshot = debug_info_copy(debug_info);

        if(!debug_info_snapshot){
#ifdef DEBUG
                printk(KERN_ERR "debug_open: debug_info_copy failed (out of mem)\n");
#endif
                rc = -ENOMEM;
                goto out;
        }

        if ((file->private_data =
             kmalloc(sizeof(file_private_info_t), GFP_ATOMIC)) == 0) {
#ifdef DEBUG
                printk(KERN_ERR "debug_open: kmalloc failed\n");
#endif
                debug_info_free(debug_info_snapshot);   
                rc = -ENOMEM;
                goto out;
        }
        p_info = (file_private_info_t *) file->private_data;
        p_info->offset = 0;
        p_info->debug_info_snap = debug_info_snapshot;
        p_info->debug_info_org  = debug_info;
        p_info->view = debug_info->views[i];
        p_info->act_area = 0;
        p_info->act_entry = DEBUG_PROLOG_ENTRY;
        p_info->act_entry_offset = 0;

        debug_info_get(debug_info);

      out:
        up(&debug_lock);
        if (rc != 0)
                MOD_DEC_USE_COUNT;
        return rc;
}

/*
 * debug_close:
 * - called for user close()
 * - deletes  private_data area of the file handle
 */

static int debug_close(struct inode *inode, struct file *file)
{
        file_private_info_t *p_info;
#ifdef DEBUG
        printk("debug_close\n");
#endif
        p_info = (file_private_info_t *) file->private_data;
        debug_info_free(p_info->debug_info_snap);
        debug_info_put(p_info->debug_info_org);
        kfree(file->private_data);
        MOD_DEC_USE_COUNT;
        return 0;               /* success */
}

/*
 * debug_create_proc_dir_entry:
 * - initializes proc-dir-entry and registers it
 */

static struct proc_dir_entry *debug_create_proc_dir_entry
    (struct proc_dir_entry *root, const char *name, mode_t mode,
     struct inode_operations *iops, struct file_operations *fops) 
{
        struct proc_dir_entry *rc = NULL;

#ifdef CONFIG_PROC_FS
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,3,98))
        const char *fn = name;
        int len;
        len = strlen(fn);

        rc = (struct proc_dir_entry *) kmalloc(sizeof(struct proc_dir_entry)
                                               + len + 1, GFP_ATOMIC);
        if (!rc)
                goto out;

        memset(rc, 0, sizeof(struct proc_dir_entry));
        memcpy(((char *) rc) + sizeof(*rc), fn, len + 1);
        rc->name = ((char *) rc) + sizeof(*rc);
        rc->namelen = len;
        rc->low_ino = 0, rc->mode = mode;
        rc->nlink = 1;
        rc->uid = 0;
        rc->gid = 0;
        rc->size = 0;
        rc->get_info = NULL;
        rc->ops = iops;

        proc_register(root, rc);
#else
        rc = create_proc_entry(name, mode, root);
        if (!rc)
                goto out;
        if (fops)
                rc->proc_fops = fops;
#endif

      out:
#endif /* CONFIG_PROC_FS */
        return rc;
}


/*
 * delete_proc_dir_entry:
 */

static void debug_delete_proc_dir_entry
    (struct proc_dir_entry *root, struct proc_dir_entry *proc_entry) 
{

#ifdef CONFIG_PROC_FS
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,3,98))
        proc_unregister(root, proc_entry->low_ino);
        kfree(proc_entry);
#else
        remove_proc_entry(proc_entry->name, root);
#endif
#endif /* CONFIG_PROC_FS */
}

/*
 * debug_register:
 * - creates and initializes debug area for the caller
 * - returns handle for debug area
 */

debug_info_t *debug_register
    (char *name, int page_order, int nr_areas, int buf_size) 
{
        debug_info_t *rc = NULL;

        MOD_INC_USE_COUNT;
        if (!initialized)
                debug_init();
        down(&debug_lock);

        /* create new debug_info */

        rc = debug_info_create(name, page_order, nr_areas, buf_size);
        if(!rc) 
                goto out;
        debug_register_view(rc, &debug_level_view);
        debug_register_view(rc, &debug_flush_view);
#ifdef DEBUG
        printk(KERN_INFO
               "debug: reserved %d areas of %d pages for debugging %s\n",
               nr_areas, 1 << page_order, rc->name);
#endif
      out:
        if (rc == NULL){
                printk(KERN_ERR "debug: debug_register failed for %s\n",name);
                MOD_DEC_USE_COUNT;
        }
        up(&debug_lock);
        return rc;
}

/*
 * debug_unregister:
 * - give back debug area
 */

void debug_unregister(debug_info_t * id)
{
        if (!id)
                goto out;
        down(&debug_lock);
#ifdef DEBUG
        printk(KERN_INFO "debug: unregistering %s\n", id->name);
#endif
        debug_info_put(id);
        up(&debug_lock);

        MOD_DEC_USE_COUNT;
      out:
        return;
}

/*
 * debug_set_level:
 * - set actual debug level
 */

void debug_set_level(debug_info_t* id, int new_level)
{
        unsigned long flags;
        if(!id)
                return; 
        spin_lock_irqsave(&id->lock,flags);
        if(new_level == DEBUG_OFF_LEVEL){
                id->level = DEBUG_OFF_LEVEL;
                printk(KERN_INFO "debug: %s: switched off\n",id->name);
        } else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) {
                printk(KERN_INFO
                        "debug: %s: level %i is out of range (%i - %i)\n",
                        id->name, new_level, 0, DEBUG_MAX_LEVEL);
        } else {
                id->level = new_level;
#ifdef DEBUG
                printk(KERN_INFO 
                        "debug: %s: new level %i\n",id->name,id->level);
#endif
        }
        spin_unlock_irqrestore(&id->lock,flags);
}


/*
 * proceed_active_entry:
 * - set active entry to next in the ring buffer
 */

extern inline void proceed_active_entry(debug_info_t * id)
{
        if ((id->active_entry[id->active_area] += id->entry_size)
            > ((PAGE_SIZE << (id->page_order)) - id->entry_size))
                id->active_entry[id->active_area] = 0;
}

/*
 * proceed_active_area:
 * - set active area to next in the ring buffer
 */

extern inline void proceed_active_area(debug_info_t * id)
{
        id->active_area++;
        id->active_area = id->active_area % id->nr_areas;
}

/*
 * get_active_entry:
 */

extern inline debug_entry_t *get_active_entry(debug_info_t * id)
{
        return (debug_entry_t *) ((char *) id->areas[id->active_area] +
                                  id->active_entry[id->active_area]);
}

/*
 * debug_common:
 * - set timestamp, caller address, cpu number etc.
 */

extern inline debug_entry_t *debug_common(debug_info_t * id, int level, 
                                    const void *buf, int len, int exception)
{
        unsigned long flags;
        debug_entry_t *active;

        spin_lock_irqsave(&id->lock, flags);
        active = get_active_entry(id);
        STCK(active->id.stck);
        active->id.fields.cpuid = smp_processor_id();
        active->caller = __builtin_return_address(0);
        active->id.fields.exception = exception;
        active->id.fields.level     = level;
        memset(DEBUG_DATA(active), 0, id->buf_size);
        memcpy(DEBUG_DATA(active), buf, MIN(len, id->buf_size));
        proceed_active_entry(id);
        if(exception)
                proceed_active_area(id);
        spin_unlock_irqrestore(&id->lock, flags);

        return active;
}

/*
 * debug_event_common:
 * - write debug entry with given size
 */

debug_entry_t *debug_event_common(debug_info_t * id, int level, const void *buf,
                                  int len)
{
        return debug_common(id, level, buf, len, 0);
}

/*
 * debug_exception_common:
 * - write debug entry with given size and switch to next debug area
 */

debug_entry_t *debug_exception_common(debug_info_t * id, int level, 
                                      const void *buf, int len)
{
        return debug_common(id, level, buf, len, 1);
}

/*
 * counts arguments in format string for sprintf view
 */

extern inline int debug_count_numargs(char *string)
{
        int numargs=0;

        while(*string) {
                if(*string++=='%')
                        numargs++;
        }
        return(numargs);
}

/*
 * debug_sprintf_event:
 */

debug_entry_t *debug_sprintf_event(debug_info_t* id,
                                   int level,char *string,...)
{
        va_list   ap;
        int numargs,alloc_size,idx;
        debug_sprintf_entry *curr_event;
        debug_entry_t *retval = NULL;

        if((!id) || (level > id->level))
                return NULL;
        else {
                numargs=debug_count_numargs(string);
                alloc_size=offsetof(debug_sprintf_entry,args[numargs]);
                curr_event=alloca(alloc_size);

                if(curr_event){
                        va_start(ap,string);
                        curr_event->string=string;
                        for(idx=0;idx<numargs;idx++)
                                curr_event->args[idx]=va_arg(ap,long);
                        retval=debug_common(id,level, curr_event,alloc_size,0);
                        va_end(ap);
                }
                return retval;
        }
}

/*
 * debug_sprintf_exception:
 */

debug_entry_t *debug_sprintf_exception(debug_info_t* id,
                                       int level,char *string,...)
{
        va_list   ap;
        int numargs,alloc_size,idx;
        debug_sprintf_entry *curr_event;
        debug_entry_t *retval = NULL;

        if((!id) || (level > id->level))
                return NULL;
        else {
                numargs=debug_count_numargs(string);
                alloc_size=offsetof(debug_sprintf_entry,args[numargs]);
                curr_event=alloca(alloc_size);

                if(curr_event){
                        va_start(ap,string);
                        curr_event->string=string;
                        for(idx=0;idx<numargs;idx++)
                                curr_event->args[idx]=va_arg(ap,long);
                        retval=debug_common(id,level, curr_event,alloc_size,1);
                        va_end(ap);
                }
                return retval;
        }
}

/*
 * debug_init:
 * - is called exactly once to initialize the debug feature
 */

int debug_init(void)
{
        int rc = 0;

        down(&debug_lock);
        if (!initialized) {
#ifdef CONFIG_PROC_FS
                debug_proc_root_entry =
                    debug_create_proc_dir_entry(&proc_root, DEBUG_DIR_ROOT,
                                                S_IFDIR | S_IRUGO | S_IXUGO
                                                | S_IWUSR | S_IWGRP, NULL,
                                                NULL);
#endif /* CONFIG_PROC_FS */
                printk(KERN_INFO "debug: Initialization complete\n");
                initialized = 1;
        }
        up(&debug_lock);

        return rc;
}

/*
 * debug_register_view:
 */

int debug_register_view(debug_info_t * id, struct debug_view *view)
{
        int rc = 0;
        int i;
        unsigned long flags;
        mode_t mode = S_IFREG;
        struct proc_dir_entry *pde;


        if (!id)
                goto out;
        pde = debug_create_proc_dir_entry(id->proc_root_entry,
                                          view->name, mode,
                                          &debug_inode_ops,
                                          &debug_file_ops);
        if(!pde){
                printk(KERN_WARNING "debug: create_proc_entry() failed! Cannot register view %s/%s\n", id->name,view->name);
                rc = -1;
                goto out;
        }

        spin_lock_irqsave(&id->lock, flags);
        for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
                if (id->views[i] == NULL)
                        break;
        }
        if (i == DEBUG_MAX_VIEWS) {
                printk(KERN_WARNING "debug: cannot register view %s/%s\n",
                        id->name,view->name);
                printk(KERN_WARNING 
                        "debug: maximum number of views reached (%i)!\n", i);
                debug_delete_proc_dir_entry(id->proc_root_entry, pde);
                
                rc = -1;
        }
        else {
                id->views[i] = view;
                if (view->prolog_proc || view->format_proc || view->header_proc)
                        mode |= S_IRUSR;
                if (view->input_proc)
                        mode |= S_IWUSR;
                id->proc_entries[i] = pde;
                rc = 0;
        }
        spin_unlock_irqrestore(&id->lock, flags);
      out:
        return rc;
}

/*
 * debug_unregister_view:
 */

int debug_unregister_view(debug_info_t * id, struct debug_view *view)
{

        int rc = 0;
        int i;
        unsigned long flags;

        if (!id)
                goto out;
        spin_lock_irqsave(&id->lock, flags);
        for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
                if (id->views[i] == view)
                        break;
        }
        if (i == DEBUG_MAX_VIEWS)
                rc = -1;
        else {
                debug_delete_proc_dir_entry(id->proc_root_entry,
                                            id->proc_entries[i]);               
                id->views[i] = NULL;
                rc = 0;
        }
        spin_unlock_irqrestore(&id->lock, flags);
      out:
        return rc;
}

/*
 * functions for debug-views
 ***********************************
*/

/*
 * prints out actual debug level
 */

static int debug_prolog_level_fn(debug_info_t * id,
                                 struct debug_view *view, char *out_buf)
{
        int rc = 0;

        if(id->level == -1) rc = sprintf(out_buf,"-\n");
        else rc = sprintf(out_buf, "%i\n", id->level);
        return rc;
}

/*
 * reads new debug level
 */

static int debug_input_level_fn(debug_info_t * id, struct debug_view *view,
                                struct file *file, const char *user_buf,
                                size_t in_buf_size, loff_t * offset)
{
        char input_buf[1];
        int rc = in_buf_size;

        if (*offset != 0)
                goto out;
        if (copy_from_user(input_buf, user_buf, 1)){
                rc = -EFAULT;
                goto out;
        }
        if (isdigit(input_buf[0])) {
                int new_level = ((int) input_buf[0] - (int) '0');
                debug_set_level(id, new_level);
        } else if(input_buf[0] == '-') {
                debug_set_level(id, DEBUG_OFF_LEVEL);
        } else {
                printk(KERN_INFO "debug: level `%c` is not valid\n",
                       input_buf[0]);
        }
      out:
        *offset = in_buf_size;
        return rc;              /* number of input characters */
}


/*
 * flushes debug areas
 */
 
void debug_flush(debug_info_t* id, int area)
{
        unsigned long flags;
        int i;

        if(!id)
                return;
        spin_lock_irqsave(&id->lock,flags);
        if(area == DEBUG_FLUSH_ALL){
                id->active_area = 0;
                memset(id->active_entry, 0, id->nr_areas * sizeof(int));
                for (i = 0; i < id->nr_areas; i++) 
                        memset(id->areas[i], 0, PAGE_SIZE << id->page_order);
                printk(KERN_INFO "debug: %s: all areas flushed\n",id->name);
        } else if(area >= 0 && area < id->nr_areas) {
                id->active_entry[area] = 0;
                memset(id->areas[area], 0, PAGE_SIZE << id->page_order);
                printk(KERN_INFO
                        "debug: %s: area %i has been flushed\n",
                        id->name, area);
        } else {
                printk(KERN_INFO
                        "debug: %s: area %i cannot be flushed (range: %i - %i)\n",
                        id->name, area, 0, id->nr_areas-1);
        }
        spin_unlock_irqrestore(&id->lock,flags);
}

/*
 * view function: flushes debug areas 
 */
 
static int debug_input_flush_fn(debug_info_t * id, struct debug_view *view,
                                struct file *file, const char *user_buf,
                                size_t in_buf_size, loff_t * offset)
{
        char input_buf[1];
        int rc = in_buf_size;
 
        if (*offset != 0)
                goto out;
        if (copy_from_user(input_buf, user_buf, 1)){
                rc = -EFAULT;
                goto out;
        }
        if(input_buf[0] == '-') { 
                debug_flush(id, DEBUG_FLUSH_ALL);
                goto out;
        }
        if (isdigit(input_buf[0])) {
                int area = ((int) input_buf[0] - (int) '0');
                debug_flush(id, area);
                goto out;
        }

        printk(KERN_INFO "debug: area `%c` is not valid\n", input_buf[0]);

      out:
        *offset = in_buf_size;
        return rc;              /* number of input characters */
}

/*
 * prints debug header in raw format
 */

int debug_raw_header_fn(debug_info_t * id, struct debug_view *view,
                         int area, debug_entry_t * entry, char *out_buf)
{
        int rc;

        rc = sizeof(debug_entry_t);
        memcpy(out_buf,entry,sizeof(debug_entry_t));
        return rc;
}

/*
 * prints debug data in raw format
 */

static int debug_raw_format_fn(debug_info_t * id, struct debug_view *view,
                               char *out_buf, const char *in_buf)
{
        int rc;

        rc = id->buf_size;
        memcpy(out_buf, in_buf, id->buf_size);
        return rc;
}

/*
 * prints debug data in hex/ascii format
 */

static int debug_hex_ascii_format_fn(debug_info_t * id, struct debug_view *view,
                                  char *out_buf, const char *in_buf)
{
        int i, rc = 0;

        for (i = 0; i < id->buf_size; i++) {
                rc += sprintf(out_buf + rc, "%02x ",
                              ((unsigned char *) in_buf)[i]);
        }
        rc += sprintf(out_buf + rc, "| ");
        for (i = 0; i < id->buf_size; i++) {
                unsigned char c = in_buf[i];
                if (!isprint(c))
                        rc += sprintf(out_buf + rc, ".");
                else
                        rc += sprintf(out_buf + rc, "%c", c);
        }
        rc += sprintf(out_buf + rc, "\n");
        return rc;
}

/*
 * prints header for debug entry
 */

int debug_dflt_header_fn(debug_info_t * id, struct debug_view *view,
                         int area, debug_entry_t * entry, char *out_buf)
{
        struct timeval time_val;
        unsigned long long time;
        char *except_str;
        unsigned long caller;
        int rc = 0;
        unsigned int level;

        level = entry->id.fields.level;
        time = entry->id.stck;
        /* adjust todclock to 1970 */
        time -= 0x8126d60e46000000LL - (0x3c26700LL * 1000000 * 4096);
        tod_to_timeval(time, &time_val);

        if (entry->id.fields.exception)
                except_str = "*";
        else
                except_str = "-";
        caller = (unsigned long) entry->caller;
#if defined(CONFIG_ARCH_S390X)
        rc += sprintf(out_buf, "%02i %011lu:%06lu %1u %1s %02i %016lx  ",
                      area, time_val.tv_sec, time_val.tv_usec, level,
                      except_str, entry->id.fields.cpuid, caller);
#else
        caller &= 0x7fffffff;
        rc += sprintf(out_buf, "%02i %011lu:%06lu %1u %1s %02i %08lx  ",
                      area, time_val.tv_sec, time_val.tv_usec, level,
                      except_str, entry->id.fields.cpuid, caller);
#endif
        return rc;
}

/*
 * prints debug data sprintf-formated:
 * debug_sprinf_event/exception calls must be used together with this view
 */

#define DEBUG_SPRINTF_MAX_ARGS 10

int debug_sprintf_format_fn(debug_info_t * id, struct debug_view *view,
                            char *out_buf, debug_sprintf_entry *curr_event)
{
        int num_longs, num_used_args = 0,i, rc = 0;
        int index[DEBUG_SPRINTF_MAX_ARGS];

        /* count of longs fit into one entry */
        num_longs = id->buf_size /  sizeof(long); 

        if(num_longs < 1)
                goto out; /* bufsize of entry too small */
        if(num_longs == 1) {
                /* no args, we use only the string */
                strcpy(out_buf, curr_event->string);
                rc = strlen(curr_event->string);
                goto out;
        }

        /* number of arguments used for sprintf (without the format string) */
        num_used_args   = MIN(DEBUG_SPRINTF_MAX_ARGS, (num_longs - 1));

        memset(index,0, DEBUG_SPRINTF_MAX_ARGS * sizeof(int));

        for(i = 0; i < num_used_args; i++)
                index[i] = i;

        rc =  sprintf(out_buf, curr_event->string, curr_event->args[index[0]],
                curr_event->args[index[1]], curr_event->args[index[2]],
                curr_event->args[index[3]], curr_event->args[index[4]],
                curr_event->args[index[5]], curr_event->args[index[6]],
                curr_event->args[index[7]], curr_event->args[index[8]],
                curr_event->args[index[9]]);

out:

        return rc;
}

/*
 * init_module:
 */

#ifdef MODULE
int init_module(void)
{
        int rc = 0;
#ifdef DEBUG
        printk("debug_module_init: \n");
#endif
        rc = debug_init();
        if (rc) 
                printk(KERN_INFO "debug: an error occurred with debug_init\n");
        return rc;
}

/*
 * cleanup_module:
 */

void cleanup_module(void)
{
#ifdef DEBUG
        printk("debug_cleanup_module: \n");
#endif
#ifdef CONFIG_PROC_FS
        debug_delete_proc_dir_entry(&proc_root, debug_proc_root_entry);
#endif /* CONFIG_PROC_FS */
        return;
}

#endif                  /* MODULE */

EXPORT_SYMBOL(debug_register);
EXPORT_SYMBOL(debug_unregister); 
EXPORT_SYMBOL(debug_set_level);
EXPORT_SYMBOL(debug_register_view);
EXPORT_SYMBOL(debug_unregister_view);
EXPORT_SYMBOL(debug_event_common);
EXPORT_SYMBOL(debug_exception_common);
EXPORT_SYMBOL(debug_hex_ascii_view);
EXPORT_SYMBOL(debug_raw_view);
EXPORT_SYMBOL(debug_dflt_header_fn);
EXPORT_SYMBOL(debug_sprintf_view);
EXPORT_SYMBOL(debug_sprintf_exception);
EXPORT_SYMBOL(debug_sprintf_event);