Sample Code

/* * Driver for S3C2440 base board. * * Copyright (C ) 2019 Alan NWPU <[email protected]> * * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * MULTIBEANS, NP U Youyi West Ave, Beilin District, Xi'an, China. */#include  /* Every Linux kernel module must include this head */#include  /* Every Linux kernel module must include this head */#include  /* printk() */#include  /* struct fops */#include  /* error codes */#include  /* cdev_alloc() */#include  /* request_mem_region() */#include #include #include #include #include #include #include # include #include #include #include #include #include #include #define DRV_NAME "s3c2440_leds"#define DRV_AUTHOR "Alan Tian <[email protected]>"#define DRV_DESC "S3C2440 LED Pin Driver"#define S3C2440_LED_SIZE 0x1000#define S3C2440_LED_MAJOR 230#define S3C2440_LED_MI NOR 0 static int major = S3C2440_LED_MAJOR; static int minor = S3C2440_LED_MINOR; /* The second parameter when the application executes ioctl(fd, cmd, arg)*/#define IOCTL_LED_ON 0#define IOCTL_LED_OFF 1static int s_opendes s3c2440, struct struct file *filp );static long s3c2440_leds_ioctl( struct file *file, unsigned int cmd, unsigned long arg );static ssize_t s3c2440_leds_write( struct file *filp, const char __user *buffer, size_t size, loff_t static_t *3creadsize_t *3creadsize_t ); (struct file *filp, const char __user *buffer, size_t size, loff_t *f_pos );struct s3c2440_leds_dev_t{ struct cdev cdev; unsigned char mem[S3C2440_LED_SIZE];} *s3c2440_LED_SIZE];) *s3c2440_LED_SIZE];) *s3c2440_LED_SIZE = {.owner = THIS_MODULE, .write = s3c2440_leds_write, .read = s3c2440_leds_read, .open = s3c2440_leds_open, .unlocked_ioctl = s3c2440_leds_ioctl,};static int s3c2 440_leds_open( struct inode *inodes, struct file *filp ){ //int ret; filp->private_data = s3c2440_leds_dev; printk(DRV_NAME"\tS3C2440 open function...\n"); return 0;}static long s3c2440_leds_ioctl( struct file *file, unsigned int cmd, unsigned long arg ){ printk(DRV_NAME "\tRecv cmd: %u\n", cmd); printk(DRV_NAME "\tRecv arg: %lu\n", arg); //IO operations function. if(arg> 4) {return -EINVAL;} switch (cmd) {case IOCTL_LED_ON: s3c2410_gpio_setpin(S3C2410_GPF(arg+3), 0);//Set pin printk("Open LED %lu ",arg) ; return 0; case IOCTL_LED_OFF: s3c2410_gpio_setpin(S3C2410_GPF(arg+3), 1); printk("Close LED %lu ",arg); return 0; default: return -EINVAL; })static ssize_t s3c2440_leds_write( struct file *filp , const char __user *buffer, size_t size, loff_t *f_pos ){ unsigned long p = *f_pos; unsigned int count = size; int ret = 0; struct s3c2440_leds_dev_t *dev = filp->private_data; if(p >= S3C2440_LED_SIZE) return 0; if(count> S3C2440_LED_SIZE-p) count = S3C2440_LED_SIZE-p; memset(dev->mem), 0, S3ZE2440_LED if(copy_from_user(dev->mem + p, buffer, count)) {ret = -EFAULT;} else {*f_pos += count; ret = count; printk(KERN_INFO "writter %u bytes(s) from %lu\ n", count, p);} return ret; }static ssize_t s3c2440_leds_read( struct file *filp, const char __user *buffer, size_t size, loff_t *f_pos ){ unsigned long p = *f_pos; unsigned int count = size; int ret = 0; struct s3c2440_leds_dev_t *dev = filp->private_data; if(p >= S3C2440_LED_SIZE) return 0; if(count> S3C2440_LED_SIZE-p) count = S3C2440_LED_SIZE-p; if(copy_to_user(mem +, p dev-> , count)) {ret = -EFAULT;} else {*f_pos += count; ret = count; printk(KERN_ INFO "read %u bytes(s) from %lu\n", count, p);} return ret;}static int __init s3c2440_leds_init(void){ int ret,err; dev_t devid; if(major) {devid = MKDEV (major, 0); ret = register_chrdev_region(devid, 1, DRV_NAME); printk("Origin Creat node %d\n",major);} else {ret = alloc_chrdev_region(&devid, 0, 1, DRV_NAME); major = MAJOR(devid); printk("Arrage1 Creat node %d\n",major);} if(ret <0) {printk(DRV_NAME "\ts3c2440 new device failed\n"); //goto fail_malloc; return ret; } s3c2440_leds_dev = kzalloc(sizeof(struct s3c2440_leds_dev_t), GFP_KERNEL); if(!s3c2440_leds_dev) {ret = -ENOMEM; goto fail_malloc;} printk("success init leds\nc_40";s_dev24leds-dev_sop_dev); err = cdev_add(&s3c2440_leds_dev->cdev, devid, 1); if(err) printk(KERN_NOTICE "Error %d adding s2c2440_leds %d",err, 1); return 0; fail_malloc: unr egister_chrdev_region(devid, 1); return ret;}static void __exit s3c2440_leds_exit(void){ printk("Starting delet node %d\n",major); cdev_del(&s3c2440_leds_dev->cdev); kfree(s3c2440_leds_dev); unregister (major, minor), 1); printk("Delete node %d\n",major);}module_init(s3c2440_leds_init);module_exit(s3c2440_leds_exit);MODULE_AUTHOR(DRV_AUTHOR);MODULE_DESCRIPLICTION(DRV_DES_C");MODULE_DESCRIPLICTION(DRV_DES_C"); ;

Contents

• Blog description
• Development environment
• 1. Linux character device driver composition
  • 1.1 Character device driver module loading and unloading functions
  • 1.2 Member functions in the file_operations structure of the character device driver
• 2 . Character device driver-device number registration and uninstallation
  • 2.1 Device number registration
  • 2.2 Device number cancellation
• 3. Character device Drive-file operation
• Reference material
• Sample code