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/*
* arch/arm/mach-tegra/tegra_reg_access.c
*
* Copyright (C) 2011 NVIDIA Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <asm/io.h>
#include <mach/iomap.h>
static struct miscdevice dev;
static int tegra_reg_access_open(struct inode *inode, struct file *filp)
{
int ret;
ret = nonseekable_open(inode, filp);
if (unlikely(ret))
return ret;
return 0;
}
static int tegra_reg_access_release(struct inode *inode, struct file *filp)
{
return 0;
}
#define TEGRA_REG_WRITE 0
#define TEGRA_REG_READ 1
static long tegra_reg_access_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
/*
* For Reg Read,
* arg[0] = phys address, arg[1] = returns value read.
* For Reg Write,
* arg[0] = phys address, arg[1] = value to write.
*/
unsigned long *uarg = (unsigned long *)arg;
void __iomem *reg_addr = IO_ADDRESS(uarg[0]);
if (reg_addr == NULL)
return -EINVAL;
switch (cmd) {
case TEGRA_REG_READ:
uarg[1] = readl(reg_addr);
break;
case TEGRA_REG_WRITE:
writel(uarg[1], reg_addr);
break;
default:
pr_err("\n tegra_reg_access unknown ioctl cmd=%d\n", cmd);
return -EINVAL;
}
return 0;
}
static const struct file_operations tegra_reg_access_fops = {
.owner = THIS_MODULE,
.open = tegra_reg_access_open,
.release = tegra_reg_access_release,
.unlocked_ioctl = tegra_reg_access_ioctl,
};
static int __devinit tegra_reg_access_init(void)
{
int e;
dev.minor = MISC_DYNAMIC_MINOR;
dev.name = "tegra_reg_access";
dev.fops = &tegra_reg_access_fops;
dev.parent = NULL;
e = misc_register(&dev);
if (e) {
pr_err("\nunable to register tegra_reg_access dev\n");
return -ENODEV;
}
pr_warn("## WARNING: Tegra registers access, from user space, is enabled.\n"
"## This creates a hole in the system security.\n"
"## Ensure that this is intentional.\n");
return 0;
}
static void __exit tegra_reg_access_exit(void)
{
misc_deregister(&dev);
}
module_init(tegra_reg_access_init);
module_exit(tegra_reg_access_exit);
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