在Android5.1系统Linux内核源码内开发Android硬件驱动程序

#include <linux/init.h> #include <linux/module.h> #include <linux/types.h> #include <linux/fs.h> #include <linux/proc_fs.h> #include <linux/device.h> #include <asm/uaccess.h> #include "freg.h" static int freg_major = 0; static int freg_minor = 0; static struct class* freg_class = NULL; static struct fake_reg_dev* freg_dev = NULL; static int freg_open(struct inode* inode, struct file* filp); static int freg_release(struct inode* inode, struct file* filp); static ssize_t freg_read(struct file* filp, char __user *buf, size_t count, loff_t* f_pos); static ssize_t freg_write(struct file* filp, const char __user *buf, size_t count, loff_t* f_pos); static struct file_operations freg_fops = { .owner = THIS_MODULE, .open = freg_open, .release = freg_release, .read = freg_read, .write = freg_write, }; static ssize_t freg_val_show(struct device* dev, struct device_attribute* attr, char* buf); static ssize_t freg_val_store(struct device* dev, struct device_attribute* attr, const char* buf, size_t count); static DEVICE_ATTR(val, S_IRUGO | S_IWUSR, freg_val_show, freg_val_store); static int freg_open(struct inode* inode, struct file* filp) { struct fake_reg_dev* dev; dev = container_of(inode->i_cdev, struct fake_reg_dev, dev); filp->private_data = dev; return 0; } static int freg_release(struct inode* inode, struct file* filp) { return 0; } static ssize_t freg_read(struct file* filp, char __user *buf, size_t count, loff_t* f_pos) { ssize_t err = 0; struct fake_reg_dev* dev = filp->private_data; if(down_interruptible(&(dev->sem))) { return -ERESTARTSYS; } if(count < sizeof(dev->val)) { goto out; } if(copy_to_user(buf, &(dev->val), sizeof(dev->val))) { err = -EFAULT; goto out; } err = sizeof(dev->val); out: up(&(dev->sem)); return err; } static ssize_t freg_write(struct file* filp, const char __user *buf, size_t count, loff_t* f_pos) { struct fake_reg_dev* dev = filp->private_data; ssize_t err = 0; if(down_interruptible(&(dev->sem))) { return -ERESTARTSYS; } if(count != sizeof(dev->val)) { goto out; } if(copy_from_user(&(dev->val), buf, count)) { err = -EFAULT; goto out; } err = sizeof(dev->val); out: up(&(dev->sem)); return err; } static ssize_t __freg_get_val(struct fake_reg_dev* dev, char* buf) { int val = 0; if(down_interruptible(&(dev->sem))) { return -ERESTARTSYS; } val = dev->val; up(&(dev->sem)); return snprintf(buf, PAGE_SIZE, "%d\n", val); } static ssize_t __freg_set_val(struct fake_reg_dev* dev, const char* buf, size_t count) { int val = 0; val = simple_strtol(buf, NULL, 10); if(down_interruptible(&(dev->sem))) { return -ERESTARTSYS; } dev->val = val; up(&(dev->sem)); return count; } static ssize_t freg_val_show(struct device* dev, struct device_attribute* attr, char* buf) { struct fake_reg_dev* hdev = (struct fake_reg_dev*)dev_get_drvdata(dev); return __freg_get_val(hdev, buf); } static ssize_t freg_val_store(struct device* dev, struct device_attribute* attr, const char* buf, size_t count) { struct fake_reg_dev* hdev = (struct fake_reg_dev*)dev_get_drvdata(dev); return __freg_set_val(hdev, buf, count); } static ssize_t freg_proc_read(char* page, char** start, off_t off, int count, int* eof, void* data) { if(off > 0) { *eof = 1; return 0; } return __freg_get_val(freg_dev, page); } static ssize_t freg_proc_write(struct file* filp, const char __user *buff, unsigned long len, void* data) { int err = 0; char* page = NULL; if(len > PAGE_SIZE) { printk(KERN_ALERT"The buff is too large: %lu.\n", len); return -EFAULT; } page = (char*)__get_free_page(GFP_KERNEL); if(!page) { printk(KERN_ALERT"Failed to alloc page.\n"); return -ENOMEM; } if(copy_from_user(page, buff, len)) { printk(KERN_ALERT"Failed to copy buff from user.\n"); err = -EFAULT; goto out; } err = __freg_set_val(freg_dev, page, len); out: free_page((unsigned long)page); return err; } static void freg_create_proc(void) { struct proc_dir_entry* entry; entry = create_proc_entry(FREG_DEVICE_PROC_NAME, 0, NULL); if(entry) { //entry->owner = THIS_MODULE; entry->read_proc = freg_proc_read; entry->write_proc = freg_proc_write; } } static void freg_remove_proc(void) { remove_proc_entry(FREG_DEVICE_PROC_NAME, NULL); } static int __freg_setup_dev(struct fake_reg_dev* dev) { int err; dev_t devno = MKDEV(freg_major, freg_minor); memset(dev, 0, sizeof(struct fake_reg_dev)); cdev_init(&(dev->dev), &freg_fops); //dev->dev.owner = THIS_MODULE; dev->dev.ops = &freg_fops; err = cdev_add(&(dev->dev),devno, 1); if(err) { return err; } //init_MUTEX(&(dev->sem)); sema_init(&(dev->sem), 1); dev->val = 0; return 0; } static int __init freg_init(void) { int err = -1; dev_t dev = 0; struct device* temp = NULL; printk(KERN_ALERT"Initializing freg device.\n"); err = alloc_chrdev_region(&dev, 0, 1, FREG_DEVICE_NODE_NAME); if(err < 0) { printk(KERN_ALERT"Failed to alloc char dev region.\n"); goto fail; } freg_major = MAJOR(dev); freg_minor = MINOR(dev); freg_dev = kmalloc(sizeof(struct fake_reg_dev), GFP_KERNEL); if(!freg_dev) { err = -ENOMEM; printk(KERN_ALERT"Failed to alloc freg device.\n"); goto unregister; } err = __freg_setup_dev(freg_dev); if(err) { printk(KERN_ALERT"Failed to setup freg device: %d.\n", err); goto cleanup; } freg_class = class_create(THIS_MODULE, FREG_DEVICE_CLASS_NAME); if(IS_ERR(freg_class)) { err = PTR_ERR(freg_class); printk(KERN_ALERT"Failed to create freg device class.\n"); goto destroy_cdev; } temp = device_create(freg_class, NULL, dev, "%s", FREG_DEVICE_FILE_NAME); if(IS_ERR(temp)) { err = PTR_ERR(temp); printk(KERN_ALERT"Failed to create freg device.\n"); goto destroy_class; } err = device_create_file(temp, &dev_attr_val); if(err < 0) { printk(KERN_ALERT"Failed to create attribute val of freg device.\n"); goto destroy_device; } dev_set_drvdata(temp, freg_dev); freg_create_proc(); printk(KERN_ALERT"Succedded to initialize freg device.\n"); return 0; destroy_device: device_destroy(freg_class, dev); destroy_class: class_destroy(freg_class); destroy_cdev: cdev_del(&(freg_dev->dev)); cleanup: kfree(freg_dev); unregister: unregister_chrdev_region(MKDEV(freg_major, freg_minor), 1); fail: return err; } static void __exit freg_exit(void) { dev_t devno = MKDEV(freg_major, freg_minor); printk(KERN_ALERT"Destroy freg device.\n"); freg_remove_proc(); if(freg_class) { device_destroy(freg_class, MKDEV(freg_major, freg_minor)); class_destroy(freg_class); } if(freg_dev) { cdev_del(&(freg_dev->dev)); kfree(freg_dev); } unregister_chrdev_region(devno, 1); } MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Fake Register Driver"); module_init(freg_init); module_exit(freg_exit);