本文主要介紹字符驅(qū)動編程(字符驅(qū)動程序)，下面一起看看字符驅(qū)動編程(字符驅(qū)動程序)相關(guān)資訊。
在上一篇文章中，我記錄了字符設(shè)備的發(fā)展。來讀寫內(nèi)存數(shù)據(jù)，但是有一個問題。設(shè)備的創(chuàng)建依賴于手動mknod。無論改進與否，設(shè)備的自動創(chuàng)建都可以通過直接加載驅(qū)動程序來完成。這里增加了class_create的創(chuàng)建，實現(xiàn)驅(qū)動的加載，設(shè)備創(chuàng)建，同步觸發(fā)。對于基于平臺的設(shè)備，這樣的創(chuàng)建也是可以接受的。代碼附錄如下:
include linux/module . hinc lude linux/types . hinc lude linux/fs . hinc lude linux/errno . hinc lude linux/mm . hinc lude linux/sched . hinc lude linux/init . hinc lude linux/cdev . hinc lude linux/uaccess . hinc lude linux/slab . hdefine globamem _ size 0x 1000 define mem _ clear 0x 1 define global mem _ major 0 define ins mod _ create _ devstatic int global mem _ major = global mem靜態(tài)結(jié)構(gòu)類* gmem _ class
/* globalmem設(shè)備結(jié)構(gòu)*/structglobalmem _ dev { structcdev cdev；無符號字符mem[globamem _ size]；};
struct global mem _ dev global mem _ devp；/文件打開函數(shù)*/int global mem _ open(struct inode * inode，struct file filp){//filp-private _ data = global mem _ devp；返回0；}/文件釋放函數(shù)*/int global mem _ release(struct inode * inode，struct file * filp){ return 0；}
/* ioctl設(shè)備控制函數(shù)*/staticlongglobalmem _ ioctl(struct file * filp，unsigned int cmd，unsigned long arg) {//stru)ct global mem _ dev dev = filp-private _ data；/獲取設(shè)備結(jié)構(gòu)指針*/
switch(cmd){ case mem _ clear:mem set(dev-mem，0，globamem _ size)；printk(kern _ info globalmem被設(shè)置為零);打破；default : return-einval；}返回0；}
/* read function */static size _ t global mem _ read(struct file * filp，char _ _ user * buf，size _ t size，loft _ t * ppos) {
無符號長p = * pposunsigned int count = sizeint ret = 0；struct global mem _ dev * dev = filp-private _ data；/*獲取設(shè)備結(jié)構(gòu)指針*/ if (p = globamem_size)返回0；if(count globamem _ size-p)count = globamem _ size-p；/*內(nèi)核空間-用戶空間*/if (copy _ to _ user (buf，(void *) (dev-memp)，count)){ ret = efault；} else { * ppos = countret =計數(shù)；printk(kern _ info 從%lu讀取%u字節(jié)\ n ，計數(shù)，p)；ret返回；} static ssize _ t global mem _ write(struct file * filp，const char __user *buf，size_t size，loff_t *ppos){
無符號長p = * pposunsigned int count = sizeint ret = 0；struct global mem _ dev * dev = filp-private _ data；/*獲取設(shè)備結(jié)構(gòu)指針*/ if (p = globamem_size)返回0；如果(計數(shù)globamem _ size-p)count = globamem _ size-p；/*用戶空間-內(nèi)核空間*/if(copy _ from _ user((void *)(dev-memp)，buf，count)){ ret = e fault；} else { * ppos = countret =計數(shù)；printk(kern _ info 從%lu寫入%u字節(jié)\ n ，計數(shù)，p)；ret返回；} static loff _ t global mem _ ll seek(struct file * filp，loff_t offset，int orig){
int ret = 0；struct global mem _ dev * dev = filp-private _ data；/*獲取設(shè)備結(jié)構(gòu)指針*/ret ret；}/*文件操作結(jié)構(gòu)*/static construct file _ operationglobalmem _ fops = {。owner = this _ module，。llseek = globalmem _ llseek，。read = globalmem _ read，。write = globalmem_write，。unlocked_ioctl = globalmem_ioctl，。open = globalmem_open，。release = globalmem_release，}；
/*初始化并注冊cdev */staticvoid全局mem _ setup _ cdev (struct全局mem _ dev * dev，int index) {interr，devno = mkdev(全局mem _ major，index)；cdev_init(dev-cdev，global mem _ fops)；dev-cdev . owner = this _ module；err = cdev_add(dev-cdev，devno，1)；if(err)printk(kern _ notice 添加globalmem %d時出現(xiàn)錯誤% d ，err，index)；}
/*設(shè)備驅(qū)動程序模塊加載函數(shù)*/int globalmem_init(void){
我fdef ins mod _ create _ devglobalmem _ major = register _ chrdev(0， gmem ，global mem _ fops)；gmem _ class = class _ create(this _ module gmem );device_create(gmem_class，null，mkdev(globalmem_major，0)，null， mgem );/*/dev/led */global mem _ devp = kmalloc(sizeof(struct global mem _ dev)，gfp _ kernel)；如果(！globalmem_devp) {/*應(yīng)用程序失敗*/printk(kern _ notice 錯誤kmalloc失敗 );}返回0；elseint結(jié)果；dev _ t devno = mkdev(global mem _ major，0)；//* devno = (25020) | 0 *//* *應(yīng)用設(shè)備號*/if(global mem _ major)result = register _ chrdev _ region(devno，1， 全球記憶 );else {/*動態(tài)應(yīng)用設(shè)備編號*/result = alloc _ chr dev _ region(devno，0，1 全球記憶與記憶);global mem _ major = major(devno)；}if(結(jié)果0)返回結(jié)果；/*動態(tài)申請設(shè)備結(jié)構(gòu)的內(nèi)存*/global mem _ devp = kmalloc(sizeof(structglobalmem _ dev)，gfp _ kernel)；如果(！globalmem_devp) {/*應(yīng)用程序失敗*/result =-eno mem；goto fail _ malloc}memset (globalmem_devp，0，sizeof(struct global mem _ dev))；global mem _ setup _ cdev(global mem _ devp，0)；返回0；fail _ malloc: unregister _ chrdev _ region(devno，1)；返回result
endif}
/*模塊卸載函數(shù)*/void globalmem_exit(void){
ifdef ins mod _ create _ dev unregister _ chrdev(global mem _ major， gmem );device_destroy(gmem_class，mkdev(globalmem_major，0))；class _ destroy(gmem _ class)；elsecdev _ del(global mem _ devp-cdev)；/*注銷cdev */kfree(global mem _ devp)；/*釋放設(shè)備結(jié)構(gòu)的內(nèi)存*/unregister _ chrdev _ region(mkdev(global mem _ major，0)，1)；/*發(fā)布設(shè)備號*/endif}
模塊作者( 傅立葉和傅立葉變換);模塊許可證( 雙bsd/gpl );
module_param(globalmem_major，int，s _ i rugo)；
module_init(全局內(nèi)存_初始化)；模塊_出口(全局內(nèi)存_出口)；
標簽:
設(shè)備結(jié)構(gòu)
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