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myled.c
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myled.c
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// SPDX-License-Identifier: GPL-3.0
// Copyright (C) 2021 Ryuichi Ueda. All rights reserved.
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/delay.h>
MODULE_AUTHOR("Ryuichi Ueda & Yuwa Aoki");
MODULE_DESCRIPTION("driver for LED control");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.0.1");
static dev_t dev;
static struct cdev cdv;
static struct class *cls = NULL;
static volatile u32 *gpio_base = NULL;
static ssize_t ROM_read(struct file* filp, char* buf, size_t count, loff_t* pos)
{
int size = 0;
char ROM[] = {'R', 'O', 'M', 0x0A};
if(copy_to_user(buf+size, (const char *)ROM, sizeof(ROM))){
printk(KERN_INFO "ROM : copy_to_user failed\n");
return -EFAULT;
}
size += sizeof(ROM);
return size;
}
static ssize_t led_write(struct file* filp, const char* buf, size_t count, loff_t* pos)
{
char c;
long t1 = 100;
long t2 = 1000;
if(copy_from_user(&c,buf,sizeof(char)))
return -EFAULT;
if(c == '0'){
gpio_base[10] = 1<< 25;
}else if(c == '1'){
gpio_base[7] = 1<< 25;
mdelay(t1);
gpio_base[10] = 1<< 25;
mdelay(t2);
gpio_base[7] = 1<< 25;
mdelay(t1);
gpio_base[10] = 1<< 25;
mdelay(t2);
gpio_base[7] = 1<< 25;
mdelay(t1);
gpio_base[10] = 1<< 25;
mdelay(t2);
gpio_base[7] = 1<< 25;
mdelay(t1);
gpio_base[10] = 1<< 25;
mdelay(t2);
gpio_base[7] = 1<< 25;
mdelay(t1);
gpio_base[10] = 1<< 25;
mdelay(t2);
gpio_base[7] = 1<< 25;
mdelay(t1);
gpio_base[10] = 1<< 25;
}
return 1;
}
static struct file_operations led_fops = {
.owner = THIS_MODULE,
.write = led_write,
.read = ROM_read
};
static int __init init_mod(void)
{
int retval;
gpio_base = ioremap_nocache(0xfe200000, 0xA0);
const u32 led = 25;
const u32 index = led/10;
const u32 shift = (led%10)*3;
const u32 mask = ~(0x7 << shift);
gpio_base[index] = (gpio_base[index] & mask) | (0x1 << shift);
retval = alloc_chrdev_region(&dev, 0, 1, "myled");
if(retval < 0){
printk(KERN_INFO "alloc_chrdev_region failed.\n");
return retval;
}
printk(KERN_INFO "%s is loaded. major:%d\n", __FILE__,MAJOR(dev));
cdev_init(&cdv, &led_fops);
retval = cdev_add(&cdv, dev, 1);
if(retval < 0){
printk(KERN_ERR "cdev_add failed. major:%d. minor:%d\n", MAJOR(dev), MINOR(dev));
}
cls = class_create(THIS_MODULE, "myled");
if(IS_ERR(cls)){
printk(KERN_ERR "class_create failed.\n");
return PTR_ERR(cls);
}
device_create(cls, NULL, dev, NULL, "myled%d", MINOR(dev));
return 0;
}
static void __exit cleanup_mod(void)
{
cdev_del(&cdv);
class_destroy(cls);
unregister_chrdev_region(dev, 1);
printk(KERN_INFO "%s is unloaded. major:%d\n", __FILE__,MAJOR(dev));
}
module_init(init_mod);
module_exit(cleanup_mod);