/* * allocator.c -- allocate after high_memory, if available * * Copyright (C) 1998,2000   rubini@linux.it (Alessandro Rubini) * *   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. * */#ifndef __KERNEL__#  define __KERNEL__#endif#ifdef MODULE#  define EXPORT_SYMTAB#endif#include <linux/version.h>#include <linux/config.h>#include <linux/module.h>#include <linux/sched.h>#include <linux/kernel.h>#include <linux/fs.h>#include <linux/proc_fs.h>#include <linux/errno.h>#include <linux/types.h>#include <asm/page.h>#include "sysdep.h"#include "allocator.h"MODULE_AUTHOR("Alessandro Rubini");#ifdef MODULE/* export symbols, using a different approach for 2.0 */#  ifdef __USE_OLD_SYMTAB__static struct symbol_table allocator_syms = {#include <linux/symtab_begin.h>        X(allocator_allocate_dma),        X(allocator_free_dma),#include <linux/symtab_end.h>};#    define allocator_register_symtab()  register_symtab(&allocator_syms)#  else /* new way (2.2, 2.4) */EXPORT_SYMBOL(allocator_allocate_dma);EXPORT_SYMBOL(allocator_free_dma);#    define  allocator_register_symtab()  /* nothing */#  endif /* symtab way */#else#define allocator_register_symtab() /* nothing */#endif /* module */#define ALL_MSG "allocator: "#undef PDEBUG             /* undef it, just in case */#ifdef ALL_DEBUG#  ifdef __KERNEL__     /* This one if debugging is on, and kernel space */#    define PDEBUG(fmt, args...) printk( KERN_DEBUG ALL_MSG fmt, ## args)#  else     /* This one for user space */#    define PDEBUG(fmt, args...) fprintf(stderr, fmt, ## args)#  endif#else#  define PDEBUG(fmt, args...) /* not debugging: nothing */#endif#undef PDEBUGG#define PDEBUGG(fmt, args...) /* nothing: it's a placeholder *//* This is meant to be a parameter: 0 = probe, pos. = megs, neg. = disable */int allocator_himem = 0;static unsigned long allocator_buffer      = 0;  /* physical address */static unsigned long allocator_buffer_size = 0;  /* bytes *//* * The allocator keeps a list of DMA areas, so multiple devices * can coexist. The list is kept sorted by address */struct allocator_struct {    unsigned long address;    unsigned long size;    struct allocator_struct *next;};struct allocator_struct *allocator_list = NULL;#if 0static int dump_list(void){    struct allocator_struct *ptr;    PDEBUG("Current list:\n");    for (ptr = allocator_list; ptr; ptr = ptr->next) {        PDEBUG("0x%08lx (size %likB)\n",ptr->address,ptr->size>>10);    }    return 0;}#endif/* ======================================================================== * This function is the actual allocator. * * If space is available in high memory (as detected at load time), that * one is returned. The return value is a physical address (i.e., it can * be used straight ahead for DMA, but needs remapping for program use). */unsigned long allocator_allocate_dma (unsigned long bytes, int prio){    struct allocator_struct *ptr = allocator_list, *newptr;    /* check if high memory is available */    if (!allocator_buffer)        return 0;     /* Round it to a multiple of the pagesize */     bytes = PAGE_ALIGN(bytes);    PDEBUG("request for %li bytes\n", bytes);    while (ptr && ptr->next) {        if (ptr->next->address - (ptr->address + ptr->size) >= bytes)            break; /* enough space */        ptr = ptr->next;    }    if (!ptr->next) {        /* dump_list(); */        PDEBUG("alloc failed\n");        return 0; /* end of list */    }    newptr = kmalloc(sizeof(struct allocator_struct),prio);    if (!newptr)        return 0;    /* ok, now stick it after ptr */    newptr->address = ptr->address + ptr->size;    newptr->size = bytes;    newptr->next = ptr->next;    ptr->next = newptr;    /* dump_list(); */    PDEBUG("returning 0x%08lx\n",newptr->address);    return newptr->address;}int allocator_free_dma (unsigned long address){    struct allocator_struct *ptr = allocator_list, *prev;    while (ptr && ptr->next) {        if (ptr->next->address == address)            break;	ptr = ptr->next;	}    /* the one being freed is ptr->next */    prev = ptr; ptr = ptr->next;    if (!ptr) {        printk(KERN_ERR ALL_MSG "free_dma(0x%08lx) but add. not allocated\n",               ptr->address);        return -EINVAL;    }    PDEBUGG("freeing: %08lx (%li) next %08lx\n",ptr->address,ptr->size,	   ptr->next->address);    prev->next = ptr->next;    kfree(ptr);    /* dump_list(); */    return 0;}/* ======================================================================== * Init and cleanup * * On cleanup everything is released. If the list is not empty, that a * problem of our clients */int allocator_init(void){    /* check how much free memory is there */    volatile void *remapped;    unsigned long trial_size = allocator_himem<<20;    unsigned long last_trial = 0;    int step = !(allocator_himem); /* no step if size known */    unsigned long i=0;    struct allocator_struct *head, *tail;    char test_string[]="0123456789abcde"; /* 16 bytes */    PDEBUGG("himem = %i\n",allocator_himem);    if (allocator_himem < 0) /* don't even try */        return -EINVAL;    if (!trial_size) trial_size = 1<<20; /* not specified: try one meg */    while (1) {        remapped = ioremap(__pa(high_memory), trial_size);        if (!remapped)            break;        PDEBUGG("Trying %li megs (at %p, %p)\n",trial_size>>20,	       (void *)__pa(high_memory), remapped);        for (i=last_trial; i<trial_size; i+=16) {            strcpy((char *)(remapped)+i, test_string);            if (strcmp((char *)remapped+i, test_string))                break;        }        iounmap((void *)remapped);        schedule();        last_trial = trial_size;        if (i==trial_size)            trial_size <<= step; /* double, if all went well */        else            break;        if (!step) break;    }    PDEBUG("%li megs (%li k, %li b)\n",i>>20,i>>10,i);    allocator_buffer_size = i;    allocator_buffer = __pa(high_memory);    if (!allocator_buffer_size) {        printk(KERN_WARNING ALL_MSG "no free high memory to use\n");        return -ENOMEM;    }    /*     * to simplify things, always have two cells in the list:     * the first and the last. This avoids some conditionals and     * extra code when allocating and deallocating: we only play     * in the middle of the list     */    head = kmalloc(sizeof(struct allocator_struct),GFP_KERNEL);    if (!head)        return -ENOMEM;    tail = kmalloc(sizeof(struct allocator_struct),GFP_KERNEL);    if (!tail) {        kfree(head);        return -ENOMEM;    }    head->size = tail->size = 0;    head->address = allocator_buffer;    tail->address = allocator_buffer + allocator_buffer_size;    head->next = tail;    tail->next = NULL;    allocator_list = head;    allocator_register_symtab(); /* only used for 2.0 if this is a module */    return 0; /* ok, ready */}void allocator_cleanup(void){    struct allocator_struct *ptr, *next;    for (ptr = allocator_list; ptr; ptr = next) {        next = ptr->next;        PDEBUG("freeing list: 0x%08lx\n",ptr->address);        kfree(ptr);    }    allocator_buffer      = 0;    allocator_buffer_size = 0;    allocator_list = NULL;}module_init(allocator_init);module_exit(allocator_cleanup);