flash.c

Go to the documentation of this file.

/* flash.c: Allow mmap access to the OBP Flash, for OBP updates.
 *
 * Copyright (C) 1997  Eddie C. Dost  ([email protected])
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/of.h>
#include <linux/of_device.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/upa.h>

static DEFINE_MUTEX(flash_mutex);
static DEFINE_SPINLOCK(flash_lock);
static struct {
    unsigned long read_base;    /* Physical read address */
    unsigned long write_base;   /* Physical write address */
    unsigned long read_size;    /* Size of read area */
    unsigned long write_size;   /* Size of write area */
    unsigned long busy;     /* In use? */
} flash;

#define FLASH_MINOR 152

static int
flash_mmap(struct file *file, struct vm_area_struct *vma)
{
    unsigned long addr;
    unsigned long size;

    spin_lock(&flash_lock);
    if (flash.read_base == flash.write_base) {
        addr = flash.read_base;
        size = flash.read_size;
    } else {
        if ((vma->vm_flags & VM_READ) &&
            (vma->vm_flags & VM_WRITE)) {
            spin_unlock(&flash_lock);
            return -EINVAL;
        }
        if (vma->vm_flags & VM_READ) {
            addr = flash.read_base;
            size = flash.read_size;
        } else if (vma->vm_flags & VM_WRITE) {
            addr = flash.write_base;
            size = flash.write_size;
        } else {
            spin_unlock(&flash_lock);
            return -ENXIO;
        }
    }
    spin_unlock(&flash_lock);

    if ((vma->vm_pgoff << PAGE_SHIFT) > size)
        return -ENXIO;
    addr = vma->vm_pgoff + (addr >> PAGE_SHIFT);

    if (vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT)) > size)
        size = vma->vm_end - (vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT));

    vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

    if (io_remap_pfn_range(vma, vma->vm_start, addr, size, vma->vm_page_prot))
        return -EAGAIN;
        
    return 0;
}

static long long
flash_llseek(struct file *file, long long offset, int origin)
{
    mutex_lock(&flash_mutex);
    switch (origin) {
        case 0:
            file->f_pos = offset;
            break;
        case 1:
            file->f_pos += offset;
            if (file->f_pos > flash.read_size)
                file->f_pos = flash.read_size;
            break;
        case 2:
            file->f_pos = flash.read_size;
            break;
        default:
            mutex_unlock(&flash_mutex);
            return -EINVAL;
    }
    mutex_unlock(&flash_mutex);
    return file->f_pos;
}

static ssize_t
flash_read(struct file * file, char __user * buf,
       size_t count, loff_t *ppos)
{
    loff_t p = *ppos;
    int i;

    if (count > flash.read_size - p)
        count = flash.read_size - p;

    for (i = 0; i < count; i++) {
        u8 data = upa_readb(flash.read_base + p + i);
        if (put_user(data, buf))
            return -EFAULT;
        buf++;
    }

    *ppos += count;
    return count;
}

static int
flash_open(struct inode *inode, struct file *file)
{
    mutex_lock(&flash_mutex);
    if (test_and_set_bit(0, (void *)&flash.busy) != 0) {
        mutex_unlock(&flash_mutex);
        return -EBUSY;
    }

    mutex_unlock(&flash_mutex);
    return 0;
}

static int
flash_release(struct inode *inode, struct file *file)
{
    spin_lock(&flash_lock);
    flash.busy = 0;
    spin_unlock(&flash_lock);

    return 0;
}

static const struct file_operations flash_fops = {
    /* no write to the Flash, use mmap
     * and play flash dependent tricks.
     */
    .owner =    THIS_MODULE,
    .llseek =   flash_llseek,
    .read =     flash_read,
    .mmap =     flash_mmap,
    .open =     flash_open,
    .release =  flash_release,
};

static struct miscdevice flash_dev = { FLASH_MINOR, "flash", &flash_fops };

static int __devinit flash_probe(struct platform_device *op)
{
    struct device_node *dp = op->dev.of_node;
    struct device_node *parent;

    parent = dp->parent;

    if (strcmp(parent->name, "sbus") &&
        strcmp(parent->name, "sbi") &&
        strcmp(parent->name, "ebus"))
        return -ENODEV;

    flash.read_base = op->resource[0].start;
    flash.read_size = resource_size(&op->resource[0]);
    if (op->resource[1].flags) {
        flash.write_base = op->resource[1].start;
        flash.write_size = resource_size(&op->resource[1]);
    } else {
        flash.write_base = op->resource[0].start;
        flash.write_size = resource_size(&op->resource[0]);
    }
    flash.busy = 0;

    printk(KERN_INFO "%s: OBP Flash, RD %lx[%lx] WR %lx[%lx]\n",
           op->dev.of_node->full_name,
           flash.read_base, flash.read_size,
           flash.write_base, flash.write_size);

    return misc_register(&flash_dev);
}

static int __devexit flash_remove(struct platform_device *op)
{
    misc_deregister(&flash_dev);

    return 0;
}

static const struct of_device_id flash_match[] = {
    {
        .name = "flashprom",
    },
    {},
};
MODULE_DEVICE_TABLE(of, flash_match);

static struct platform_driver flash_driver = {
    .driver = {
        .name = "flash",
        .owner = THIS_MODULE,
        .of_match_table = flash_match,
    },
    .probe      = flash_probe,
    .remove     = __devexit_p(flash_remove),
};

module_platform_driver(flash_driver);

MODULE_LICENSE("GPL");