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/*
* This is a simple character device driver to illustrate the support for debug of Linux kernel modules
*
* Copyright (C) ARM Limited, 2010. All rights reserved.
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <asm/uaccess.h>
#define MODEX_MAJOR 42
#define MODEX_MINOR 0
#define DEVICE_NAME "modex"
static int modex_open(struct inode *inode, struct file *file);
static int modex_release(struct inode *inode, struct file *file);
static ssize_t modex_read (struct file *file, char *buffer, size_t length, loff_t * offset);
static ssize_t modex_write (struct file *file, const char *buffer, size_t length, loff_t * offset);
static int __init modex_init(void);
static void __exit modex_exit(void);
static volatile int test_mode /* = 0 */; /* can be set from debugger */
struct file_operations modex_fops =
{
.owner = THIS_MODULE,
.open = modex_open,
.release = modex_release,
.read = modex_read,
.write = modex_write,
};
static struct device *modex_cdev;
static struct class *modex_class;
static int modex_open(struct inode *inode, struct file *file)
{
return 0 ;
}
static int modex_release(struct inode *inode, struct file *file)
{
return 0;
}
static ssize_t modex_read(struct file *file, char *buffer, size_t length, loff_t *offset)
{
char msg_buffer[920];
char* msg = msg_buffer;
int bytes_written;
const char* ctype[] = { "No cache",
"I$ only",
"D$ only",
"I & D $",
"Unified",
"RESERVED - should not see this",
"RESERVED - should not see this",
"RESERVED - should not see this" };
int msg_len;
volatile unsigned int actlr, midr, clidr, ccsidr_l1d, ccsidr_l2u;
unsigned int l1d = 0; unsigned int l2u = 2;
#ifdef __arm__
asm("mrc p15, 0, %0, c1, c0, 1" : "=r" (actlr)); //read actlr
asm("mrc p15, 0, %0, c0, c0, 0" : "=r" (midr)); //read midr
asm("mrc p15, 1, %0, c0, c0, 1" : "=r" (clidr));
asm volatile("mcr p15, 2, %0, c0, c0, 0\nisb" :: "r" (l1d)); //set csselr (cache size selection register)
asm volatile("mrc p15, 1, %0, c0, c0, 0" : "=r" (ccsidr_l1d));
asm volatile("mcr p15, 2, %0, c0, c0, 0\nisb" :: "r" (l2u)); //set csselr (cache size selection register)
asm volatile("mrc p15, 1, %0, c0, c0, 0" : "=r" (ccsidr_l2u));
#elif defined __aarch64__
asm("mrs %0, ACTLR_EL1" : "=r" (actlr));
asm("mrs %0, MIDR_EL1" : "=r" (midr));
asm("mrs %0, CLIDR_EL1" : "=r" (clidr));
asm volatile("msr CSSELR_EL1, %0\nisb" :: "r" (l1d));
asm volatile("mrs %0, CCSIDR_EL1" : "=r" (ccsidr_l1d));
asm volatile("msr CSSELR_EL1, %0\nisb" :: "r" (l2u));
asm volatile("mrs %0, CCSIDR_EL1" : "=r" (ccsidr_l2u));
#else
#error "Non-ARM compiler"
#endif
bytes_written = snprintf(msg, sizeof msg_buffer,
"ACTLR: %#.8x\n"
"MIDR: %#.8x\n"
"CLIDR: %#.8x\n"
" LoUU: %d\n"
" LoC: %d\n"
" LoUIS: %d\n"
" L7: %s\n"
" L6: %s\n"
" L5: %s\n"
" L4: %s\n"
" L3: %s\n"
" L2: %s\n"
" L1: %s\n"
, actlr, midr, clidr,
(clidr >> 27) & 0x7,
(clidr >> 24) & 0x7,
(clidr >> 21) & 0x7,
ctype[(clidr >> 18) & 0x7],
ctype[(clidr >> 15) & 0x7],
ctype[(clidr >> 12) & 0x7],
ctype[(clidr >> 9) & 0x7],
ctype[(clidr >> 6) & 0x7],
ctype[(clidr >> 3) & 0x7],
ctype[(clidr >> 0) & 0x7]);
if((clidr >> 0) & 0x7) { //there is some cache
bytes_written += snprintf(msg + bytes_written, sizeof msg_buffer - bytes_written, "Following data only reliable if the named cache exists!\n");
}
if((clidr >> 3) & 0x7) {
bytes_written += snprintf(msg + bytes_written, sizeof msg_buffer - bytes_written,
"CCSIDR L2U$: %#.8x\n"
" Sets: %d\n"
" Assoc: %d\n"
" Line Size: 2^%d words\n",
ccsidr_l2u,
((ccsidr_l2u >> 13) & 0x7fff) + 1,
((ccsidr_l2u >> 3) & 0x03ff) + 1,
((ccsidr_l2u >> 0) & 0x0007) + 2);
}
if((clidr >> 0) & 0x7) {
bytes_written += snprintf(msg + bytes_written, sizeof msg_buffer - bytes_written,
"CCSIDR L1D$: %#.8x\n"
" Sets: %d\n"
" Assoc: %d\n"
" Line Size: 2^%d words\n",
ccsidr_l1d,
((ccsidr_l1d >> 13) & 0x7fff) + 1,
((ccsidr_l1d >> 3) & 0x03ff) + 1,
((ccsidr_l1d >> 0) & 0x0007) + 2);
}
msg_len = strlen(msg);
if (*offset >= msg_len)
return 0; /* EOF */
if (*offset + length >= msg_len)
length = msg_len - *offset;
if ( copy_to_user(buffer, msg + *offset, length) )
return -EFAULT;
*offset += length;
return length;
}
static ssize_t modex_write(struct file *file, const char *buffer, size_t length, loff_t *offset)
{
char x;
if ( copy_from_user(&x, buffer, 1) ) // only interested in the first byte passed in
return -EFAULT;
printk(KERN_INFO "modex received value: '%c' %d\n", x, x);
switch (x) {
case 'A':
if (test_mode) {
printk(KERN_INFO "modex test mode about to abort\n");
/* cause an abort */
x = *(int*)test_mode;
printk(KERN_INFO "modex didn't expect to get here! '%c' %d\n", x, x);
}
break;
case 'P':
if (test_mode) {
panic("panic from modex test mode");
}
break;
case '+':
test_mode = 1;
printk(KERN_INFO "modex test mode enabled\n");
break;
case '-':
test_mode = 0;
printk(KERN_INFO "modex test mode disabled\n");
break;
default:
break;
}
return length;
}
static int __init modex_init(void)
{
int ret;
/* Register character device driver */
ret = register_chrdev(MODEX_MAJOR, DEVICE_NAME, &modex_fops);
if (ret < 0)
{
printk(KERN_ERR "modex could not initialize\n");
return ret;
}
/* Create a class /sys/class/modex/modex, then create a device node /dev/modex */
modex_class = class_create(THIS_MODULE, DEVICE_NAME);
modex_cdev = device_create(modex_class, NULL, MKDEV (MODEX_MAJOR, MODEX_MINOR), NULL, DEVICE_NAME);
printk(KERN_INFO "modex initialized\n");
return 0;
}
static void __exit modex_exit(void)
{
device_destroy(modex_class, MKDEV (MODEX_MAJOR, MODEX_MINOR));
class_destroy(modex_class);
unregister_chrdev(MODEX_MAJOR, DEVICE_NAME);
printk(KERN_INFO "modex exited\n");
}
module_init(modex_init);
module_exit(modex_exit);
MODULE_AUTHOR("ARM");
MODULE_VERSION("1.01");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Example module");
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