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// SPDX-License-Identifier: GPL-2.0-only
/* flash.c: Allow mmap access to the OBP Flash, for OBP updates.
*
* Copyright (C) 1997 Eddie C. Dost (ecd@skynet.be)
*/
#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/mutex.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/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 flash_probe(struct platform_device *op)
{
struct device_node *dp = op->dev.of_node;
struct device_node *parent;
parent = dp->parent;
if (!of_node_name_eq(parent, "sbus") &&
!of_node_name_eq(parent, "sbi") &&
!of_node_name_eq(parent, "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 "%pOF: OBP Flash, RD %lx[%lx] WR %lx[%lx]\n",
op->dev.of_node,
flash.read_base, flash.read_size,
flash.write_base, flash.write_size);
return misc_register(&flash_dev);
}
static int 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",
.of_match_table = flash_match,
},
.probe = flash_probe,
.remove = flash_remove,
};
module_platform_driver(flash_driver);
MODULE_LICENSE("GPL");
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