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root / prex-0.9.0 / bsp / drv / dev / block / ramdisk.c @ 03e9c04a

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/*-
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 * Copyright (c) 2006, Kohsuke Ohtani
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the author nor the names of any co-contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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/*
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 * ramdisk.c - RAM disk driver
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 */
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#include <driver.h>
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/* #define DEBUG_RAMDISK 1 */
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#ifdef DEBUG_RAMDISK
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#define DPRINTF(a)        printf a
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#else
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#define DPRINTF(a)
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#endif
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/* Block size */
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#define BSIZE                512
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struct ramdisk_softc {
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        device_t        dev;                /* device object */
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        char                *addr;                /* base address of image */
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        size_t                size;                /* image size */
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};
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static int ramdisk_read(device_t, char *, size_t *, int);
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static int ramdisk_write(device_t, char *, size_t *, int);
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static int ramdisk_probe(struct driver *);
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static int ramdisk_init(struct driver *);
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static struct devops ramdisk_devops = {
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        /* open */        no_open,
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        /* close */        no_close,
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        /* read */        ramdisk_read,
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        /* write */        ramdisk_write,
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        /* ioctl */        no_ioctl,
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        /* devctl */        no_devctl,
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};
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struct driver ramdisk_driver = {
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        /* name */        "ramdisk",
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        /* devops */        &ramdisk_devops,
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        /* devsz */        sizeof(struct ramdisk_softc),
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        /* flags */        0,
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        /* probe */        ramdisk_probe,
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        /* init */        ramdisk_init,
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        /* shutdown */        NULL,
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};
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static int
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ramdisk_read(device_t dev, char *buf, size_t *nbyte, int blkno)
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{
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        struct ramdisk_softc *sc = device_private(dev);
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        int offset = blkno * BSIZE;
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        void *kbuf;
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        size_t nr_read;
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        DPRINTF(("ramdisk_read: buf=%x nbyte=%d blkno=%x\n",
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                 buf, *nbyte, blkno));
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        /* Check overrun */
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        if (offset > (int)sc->size) {
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                DPRINTF(("ramdisk_read: overrun!\n"));
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                return EIO;
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        }
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        nr_read = *nbyte;
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        if (offset + nr_read > (int)sc->size)
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                nr_read = sc->size - offset;
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        /* Translate buffer address to kernel address */
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        if ((kbuf = kmem_map(buf, nr_read)) == NULL) {
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                return EFAULT;
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        }
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        /* Copy data */
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        memcpy(kbuf, sc->addr + offset, nr_read);
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        *nbyte = nr_read;
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        return 0;
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}
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static int
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ramdisk_write(device_t dev, char *buf, size_t *nbyte, int blkno)
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{
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        struct ramdisk_softc *sc = device_private(dev);
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        int offset = blkno * BSIZE;
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        void *kbuf;
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        size_t nr_write;
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        DPRINTF(("ramdisk_write: buf=%x nbyte=%d blkno=%x\n",
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                 buf, *nbyte, blkno));
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        /* Check overrun */
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        if (offset > (int)sc->size)
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                return EIO;
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        nr_write = *nbyte;
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        if (offset + nr_write > (int)sc->size)
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                nr_write = sc->size - offset;
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        /* Translate buffer address to kernel address */
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        if ((kbuf = kmem_map(buf, nr_write)) == NULL)
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                return EFAULT;
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        /* Copy data */
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        memcpy(sc->addr + offset, kbuf, nr_write);
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        *nbyte = nr_write;
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        return 0;
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}
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static int
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ramdisk_probe(struct driver *self)
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{
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        struct bootinfo *bi;
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        struct physmem *phys;
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        machine_bootinfo(&bi);
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        phys = &bi->bootdisk;
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        if (phys->size == 0) {
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#ifdef DEBUG
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                printf("ramdisk: no bootdisk found...\n");
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#endif
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                return ENXIO;
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        }
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        return 0;
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}
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static int
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ramdisk_init(struct driver *self)
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{
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        struct ramdisk_softc *sc;
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        struct bootinfo *bi;
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        struct physmem *phys;
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        device_t dev;
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        machine_bootinfo(&bi);
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        phys = &bi->bootdisk;
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        dev = device_create(self, "ram0", D_BLK|D_PROT);
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        sc = device_private(dev);
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        sc->dev = dev;
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        sc->addr = (char *)ptokv(phys->base);
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        sc->size = (size_t)phys->size;
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#ifdef DEBUG
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        printf("RAM disk at 0x%08x (%dK bytes)\n",
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               (u_int)sc->addr, sc->size/1024);
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#endif
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        return 0;
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}