/*
* silly.c -- Simple Tool for Unloading and Printing ISA Data
*
* Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
* Copyright (C) 2001 O'Reilly & Associates
*
* The source code in this file can be freely used, adapted,
* and redistributed in source or binary form, so long as an
* acknowledgment appears in derived source files. The citation
* should list that the code comes from the book "Linux Device
* Drivers" by Alessandro Rubini and Jonathan Corbet, published
* by O'Reilly & Associates. No warranty is attached;
* we cannot take responsibility for errors or fitness for use.
*
* $Id: silly.c,v 1.3 2004/09/26 07:02:43 gregkh Exp $
*/
/* =========================> BIG FAT WARNING:
* This will only work on architectures with an ISA memory range.
* It won't work on other computers.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/version.h>
#include <linux/sched.h>
#include <linux/kernel.h> /* printk() */
#include <linux/fs.h> /* everything... */
#include <linux/errno.h> /* error codes */
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/ioport.h>
#include <linux/poll.h>
#include <asm/io.h>
#include <asm/uaccess.h>
int silly_major = 0;
module_param(silly_major, int, 0);
MODULE_AUTHOR("Alessandro Rubini");
MODULE_LICENSE("Dual BSD/GPL");
/*
* The devices access the 640k-1M memory.
* minor 0 uses ioread8/iowrite8
* minor 1 uses ioread16/iowrite16
* minor 2 uses ioread32/iowrite32
* minor 3 uses memcpy_fromio()/memcpy_toio()
*/
/*
* Here's our address range, and a place to store the ioremap'd base.
*/
#define ISA_BASE 0xA0000
#define ISA_MAX 0x100000 /* for general memory access */
#define VIDEO_MAX 0xC0000 /* for vga access */
#define VGA_BASE 0xb8000
static void __iomem *io_base;
int silly_open(struct inode *inode, struct file *filp)
{
return 0;
}
int silly_release(struct inode *inode, struct file *filp)
{
return 0;
}
enum silly_modes {M_8=0, M_16, M_32, M_memcpy};
ssize_t silly_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
int retval;
int mode = iminor(filp->f_dentry->d_inode);
void __iomem *add;
unsigned long isa_addr = ISA_BASE + *f_pos;
unsigned char *kbuf, *ptr;
if (isa_addr + count > ISA_MAX) /* range: 0xA0000-0x100000 */
count = ISA_MAX - isa_addr;
/*
* too big an f_pos (caused by a malicious lseek())
* would result in a negative count
*/
if (count < 0)
return 0;
kbuf = kmalloc(count, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
ptr = kbuf;
retval = count;
/*
* Convert our address into our remapped area.
*/
add = (void __iomem *)(io_base + (isa_addr - ISA_BASE));
/*
* kbuf is aligned, but the reads might not. In order not to
* drive me mad with unaligned leading and trailing bytes,
* I downgrade the `mode' if unaligned xfers are requested.
*/
if (mode == M_32 && ((isa_addr | count) & 3))
mode = M_16;
if (mode == M_16 && ((isa_addr | count) & 1))
mode = M_8;
switch(mode) {
case M_32:
while (count >= 4) {
*(u32 *)ptr = ioread32(add);
add += 4;
count -= 4;
ptr += 4;
}
break;
case M_16:
while (count >= 2) {
*(u16 *)ptr = ioread16(add);
add+=2;
count-=2;
ptr+=2;
}
break;
case M_8:
while (count) {
*ptr = ioread8(add);
add++;
count--;
ptr++;
}
break;
case M_memcpy:
memcpy_fromio(ptr, add, count);
break;
default:
return -EINVAL;
}
if ((retval > 0) && copy_to_user(buf, kbuf, retval))
retval = -EFAULT;
kfree(kbuf);
*f_pos += retval;
return retval;
}
ssize_t silly_write(struct file *filp, const char __user *buf, size_t count,
loff_t *f_pos)
{
int retval;
int mode = iminor(filp->f_dentry->d_inode);
unsigned long isa_addr = ISA_BASE + *f_pos;
unsigned char *kbuf, *ptr;
void __iomem *add;
/*
* Writing is dangerous.
* Allow root-only, independently of device permissions
*/
if (!capable(CAP_SYS_RAWIO))
return -EPERM;
if (isa_addr + count > ISA_MAX) /* range: 0xA0000-0x100000 */
count = ISA_MAX - isa_addr;
/*
* too big an f_pos (caused by a malicious lseek())
* results in a negative count
*/
if (count < 0)
return 0;
kbuf = kmalloc(count, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
ptr = kbuf;
retval=count;
/*
* kbuf is aligned, but the writes might not. In order not to
* drive me mad with unaligned leading and trailing bytes,
* I downgrade the `mode' if unaligned xfers are requested.
*/
if (mode == M_32 && ((isa_addr | count) & 3))
mode = M_16;
if (mode == M_16 && ((isa_addr | count) & 1))
mode = M_8;
if (copy_from_user(kbuf, buf, count)) {
kfree(kbuf);
return -EFAULT;
}
ptr = kbuf;
/*
* Switch over to our remapped address space.
*/
add = (void __iomem *)(io_base + (isa_addr - ISA_BASE));
switch(mode) {
case M_32:
while (count >= 4) {
iowrite8(*(u32 *)ptr, add);
add += 4;
count -= 4;
ptr += 4;
}
break;
case M_16:
while (count >= 2) {
iowrite8(*(u16 *)ptr, add);
add += 2;
count -= 2;
ptr += 2;
}
break;
case M_8:
while (count) {
iowrite8(*ptr, add);
add++;
count--;
ptr++;
}
break;
case M_memcpy:
memcpy_toio(add, ptr, count);
break;
default:
return -EINVAL;
}
*f_pos += retval;
kfree(kbuf);
return retval;
}
unsigned int silly_poll(struct file *filp, poll_table *wait)
{
return POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM;
}
struct file_operations silly_fops = {
.read = silly_read,
.write = silly_write,
.poll = silly_poll,
.open = silly_open,
.release = silly_release,
.owner = THIS_MODULE
};
int silly_init(void)
{
int result = register_chrdev(silly_major, "silly", &silly_fops);
if (result < 0) {
printk(KERN_INFO "silly: can't get major number\n");
return result;
}
if (silly_major == 0)
silly_major = result; /* dynamic */
/*
* Set up our I/O range.
*/
/* this line appears in silly_init */
io_base = ioremap(ISA_BASE, ISA_MAX - ISA_BASE);
return 0;
}
void silly_cleanup(void)
{
iounmap(io_base);
unregister_chrdev(silly_major, "silly");
}
module_init(silly_init);
module_exit(silly_cleanup);
