Annotation of prex/dev/gen/ramdisk.c, Revision 1.1
1.1 ! nbrk 1: /*-
! 2: * Copyright (c) 2006, Kohsuke Ohtani
! 3: * All rights reserved.
! 4: *
! 5: * Redistribution and use in source and binary forms, with or without
! 6: * modification, are permitted provided that the following conditions
! 7: * are met:
! 8: * 1. Redistributions of source code must retain the above copyright
! 9: * notice, this list of conditions and the following disclaimer.
! 10: * 2. Redistributions in binary form must reproduce the above copyright
! 11: * notice, this list of conditions and the following disclaimer in the
! 12: * documentation and/or other materials provided with the distribution.
! 13: * 3. Neither the name of the author nor the names of any co-contributors
! 14: * may be used to endorse or promote products derived from this software
! 15: * without specific prior written permission.
! 16: *
! 17: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
! 18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 20: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
! 21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 27: * SUCH DAMAGE.
! 28: */
! 29:
! 30: /*
! 31: * ramdisk.c - RAM disk driver
! 32: */
! 33:
! 34: #include <driver.h>
! 35:
! 36: /* #define DEBUG_RAMDISK 1 */
! 37:
! 38: #ifdef DEBUG_RAMDISK
! 39: #define DPRINTF(a) printf a
! 40: #else
! 41: #define DPRINTF(a)
! 42: #endif
! 43:
! 44: /* Block size */
! 45: #define BSIZE 512
! 46:
! 47: static int ramdisk_read(device_t, char *, size_t *, int);
! 48: static int ramdisk_write(device_t, char *, size_t *, int);
! 49: static int ramdisk_init(void);
! 50:
! 51: /*
! 52: * Driver structure
! 53: */
! 54: struct driver ramdisk_drv = {
! 55: /* name */ "RAM disk",
! 56: /* order */ 6,
! 57: /* init */ ramdisk_init,
! 58: };
! 59:
! 60: /*
! 61: * Device I/O table
! 62: */
! 63: static struct devio ramdisk_io = {
! 64: /* open */ NULL,
! 65: /* close */ NULL,
! 66: /* read */ ramdisk_read,
! 67: /* write */ ramdisk_write,
! 68: /* ioctl */ NULL,
! 69: /* event */ NULL,
! 70: };
! 71:
! 72: static device_t ramdisk_dev; /* Device object */
! 73:
! 74: static char *img_start;
! 75: static size_t img_size;
! 76:
! 77: static int
! 78: ramdisk_read(device_t dev, char *buf, size_t *nbyte, int blkno)
! 79: {
! 80: void *kbuf;
! 81: size_t nr_read;
! 82:
! 83: DPRINTF(("ramdisk_read: buf=%x nbyte=%d blkno=%x\n",
! 84: buf, *nbyte, blkno));
! 85:
! 86: /* Check overrun */
! 87: if ((size_t)blkno * BSIZE > img_size) {
! 88: DPRINTF(("ramdisk_read: overrun!\n"));
! 89: return EIO;
! 90: }
! 91: nr_read = *nbyte;
! 92: if ((size_t)blkno * BSIZE + nr_read > img_size)
! 93: nr_read = img_size - blkno * BSIZE;
! 94:
! 95: /* Translate buffer address to kernel address */
! 96: kbuf = kmem_map(buf, nr_read);
! 97: if (kbuf == NULL)
! 98: return EFAULT;
! 99:
! 100: /* Copy data */
! 101: memcpy(kbuf, img_start + blkno * BSIZE, nr_read);
! 102: *nbyte = nr_read;
! 103: return 0;
! 104: }
! 105:
! 106: static int
! 107: ramdisk_write(device_t dev, char *buf, size_t *nbyte, int blkno)
! 108: {
! 109: void *kbuf;
! 110: size_t nr_write;
! 111:
! 112: DPRINTF(("ramdisk_write: buf=%x nbyte=%d blkno=%x\n",
! 113: buf, *nbyte, blkno));
! 114:
! 115: /* Check overrun */
! 116: if ((size_t)blkno * BSIZE > img_size)
! 117: return EIO;
! 118: nr_write = *nbyte;
! 119: if ((size_t)blkno * BSIZE + nr_write > img_size)
! 120: nr_write = img_size - blkno * BSIZE;
! 121:
! 122: /* Translate buffer address to kernel address */
! 123: kbuf = kmem_map(buf, nr_write);
! 124: if (kbuf == NULL)
! 125: return EFAULT;
! 126:
! 127: /* Copy data */
! 128: memcpy(img_start + blkno * BSIZE, kbuf, nr_write);
! 129: *nbyte = nr_write;
! 130: return 0;
! 131: }
! 132:
! 133: /*
! 134: * Initialize
! 135: */
! 136: static int
! 137: ramdisk_init(void)
! 138: {
! 139: struct boot_info *boot_info;
! 140: struct mem_map *rd;
! 141:
! 142: machine_bootinfo(&boot_info);
! 143: rd = (struct mem_map *)&boot_info->ram_disk;
! 144: img_start = (char *)phys_to_virt((void *)rd->start);
! 145: img_size = rd->size;
! 146: if (img_size == 0)
! 147: return -1;
! 148: #ifdef DEBUG
! 149: printf("RAM disk at 0x%08x (%dK bytes)\n", img_start, img_size/1024);
! 150: #endif
! 151: /* Create device object */
! 152: ramdisk_dev = device_create(&ramdisk_io, "ram0", DF_BLK);
! 153: ASSERT(ramdisk_dev);
! 154: return 0;
! 155: }
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