{"rsdb":{"rid":"235725","subhead":"","postdate":"0","aid":"162843","fid":"105","uid":"1","topic":"1","content":"
\n

\u5982\u679c\u6211\u4eec\u7684\u7cfb\u7edf\u8981\u7528GUI\uff08\u56fe\u5f62\u754c\u9762\u63a5\u53e3\uff09\uff0c\u8fd9\u65f6LCD\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u5c31\u5e94\u8be5\u7f16\u5199\u6210frambuffer\u63a5\u53e3\uff0c\u800c\u4e0d\u662f\u50cf\u4e4b\u524d\u90a3\u6837\u53ea\u7f16\u5199\u64cd\u4f5c\u5e95\u5c42\u7684LCD\u63a7\u5236\u5668\u63a5\u53e3\u3002<\/span><\/p> \n

\u4ec0\u4e48\u662fframbuffer\u8bbe\u5907\uff1f<\/span><\/strong><\/p> \n

   frambuffer\u8bbe\u5907\u5c42\u662f\u5bf9\u56fe\u50cf\u8bbe\u5907\u7684\u4e00\u79cd\u62bd\u8c61\uff0c\u5b83\u4ee3\u8868\u4e86\u89c6\u9891\u786c\u4ef6\u7684\u5e27\u7f13\u5b58\uff0c\u4f7f\u5f97\u5e94\u7528\u7a0b\u5e8f\u901a\u8fc7\u5b9a\u4e49\u597d\u7684\u63a5\u53e3\u5c31\u53ef\u4ee5\u8bbf\u95ee\u786c\u4ef6\u3002\u6240\u4ee5\u5e94\u7528\u7a0b\u5e8f\u4e0d\u9700\u8981\u8003\u8651\u5e95\u5c42\u7684\uff08\u5bc4\u5b58\u5668\u7ea7\uff09\u7684\u64cd\u4f5c\u3002\u5e94\u7528\u7a0b\u5e8f\u5bf9\u8bbe\u5907\u6587\u4ef6\u7684\u8bbf\u95ee\u4e00\u822c\u5728\/dev\u76ee\u5f55,\u5982 \/dev\/fb*\u3002<\/span><\/p> \n

\n

 <\/p> \n

 <\/p> \n

\u5185\u6838\u4e2d\u7684frambuffer\u5728drivers\/video\/fbmem.c(fb: frame buffer)<\/span><\/p> \n

1.\u6211\u4eec\u8fdb\u5165fbmem.c\u627e\u5230\u5b83\u7684\u5165\u53e3\u51fd\u6570:<\/span><\/strong><\/span><\/p> \n

\n 
static<\/span>  int<\/span> __init  fbmem_init(void<\/span>)\r\n{\r\n\r\n         create_proc_read_entry(<\/span>"<\/span>fb<\/span>"<\/span>, 0<\/span>, NULL, fbmem_read_proc, NULL);\r\n\r\n         <\/span>if<\/span> (register_chrdev(FB_MAJOR,"<\/span>fb<\/span>"<\/span>,&fb_fops))           \/\/<\/span>(1)\u521b\u5efa\u5b57\u7b26\u8bbe\u5907<\/span>\r\n                  printk(<\/span>"<\/span>unable to get major %d for fb devs\\n<\/span>"<\/span>, FB_MAJOR);\r\n\r\n         fb_class <\/span>= class_create(THIS_MODULE, "<\/span>graphics<\/span>"<\/span>);       \/\/<\/span>\u521b\u5efa\u7c7b<\/span>\r\n\r\n         if<\/span> (IS_ERR(fb_class)) {\r\n                   printk(KERN_WARNING <\/span>"<\/span>Unable to create fb class; errno = %ld\\n<\/span>"<\/span>, PTR_ERR(fb_class));\r\n                  fb_class <\/span>= NULL;\r\n        }\r\n         <\/span>return<\/span> 0<\/span>;\r\n}<\/span><\/pre> \n <\/div> \n 
 <\/p> \n 
(1)\u521b\u5efa\u5b57\u7b26\u8bbe\u5907"fb", FB_MAJOR=29,\u4e3b\u8bbe\u5907\u53f7\u4e3a29,\u6211\u4eeccat \/proc\/devices \u4e5f\u80fd\u627e\u5230\u8fd9\u4e2a\u5b57\u7b26\u8bbe\u5907:<\/span><\/p> \n 
 \"\"<\/span><\/p> \n 
\u548c\u6211\u4eec\u4e4b\u524d\u7684\u9a71\u52a8\u7a0b\u5e8f\u4e00\u6837\uff0c\u4f46\u662f\u6ca1\u6709\u4f7f\u7528\u521b\u5efa\u8bbe\u5907\u8282\u70b9,\u4e3a\u4ec0\u4e48?<\/span><\/p> \n 
\u56e0\u4e3a\u9700\u8981\u6ce8\u518c\u4e86LCD\u9a71\u52a8\u540e\uff0c\u624d\u4f1a\u6709\u8bbe\u5907\u8282\u70b9\uff0c\u6240\u4ee5\u8fd9\u91cc\u7684\u4ee3\u7801\u6ca1\u6709 ,\u540e\u9762\u4f1a\u5206\u6790\u54ea\u91cc\u6709\u3002<\/span><\/p> \n 
2.\u6211\u4eec\u6765\u770b\u770b\u6ce8\u518c\u7684file_operations\u7ed3\u6784\u4f53fb_fops\u7684.open\u51fd\u6570\u548c.read\u51fd\u6570,\u5e94\u7528\u5c42\u662f\u5982\u4f55\u6253\u5f00\u9a71\u52a8\u3001\u8bfb\u53d6\u9a71\u52a8\u6570\u636e<\/span><\/p> \n 
2.1 fb_open\u51fd\u6570\u5982\u4e0b:<\/span><\/strong><\/p> \n 
 \n  
static<\/span> int<\/span> fb_open(struct<\/span> inode *inode, struct<\/span> file *file)\r\n{\r\n       <\/span>int<\/span> fbidx = iminor(inode);      \/\/<\/span>\u83b7\u53d6\u8bbe\u5907\u8282\u70b9\u7684\u6b21\u8bbe\u5907\u53f7<\/span>\r\n       struct<\/span> fb_info *info;                \/\/<\/span>\u5b9a\u4e49fb_info\u7ed3\u6784\u4f53<\/span>\r\n       int<\/span> res = 0<\/span>;\r\n       ... ...\r\n\r\n<\/span>if<\/span> (!(info = registered_fb[fbidx]))   \/\/<\/span>(1) info= registered_fb[fbidx],\u83b7\u53d6\u6b64\u8bbe\u5907\u53f7\u7684lcd\u9a71\u52a8\u4fe1\u606f<\/span>\r\n              try_to_load(fbidx);\r\n       ... ... \r\n\r\n       <\/span>if<\/span> (info->fbops->fb_open) {          \r\n              res <\/span>= info->fbops->fb_open(info,1<\/span>);  \/\/<\/span>\u8c03\u7528registered_fb[fbidx]->fbops->fb_open<\/span>\r\n              if<\/span> (res)\r\n                     module_put(info<\/span>->fbops->owner);\r\n       }\r\n\r\n       <\/span>return<\/span> res;\r\n}<\/span><\/pre> \n <\/div> \n 
 <\/p> \n 
(1) registered_fb[fbidx] \u8fd9\u4e2a\u6570\u7ec4\u4e5f\u662ffb_info\u7ed3\u6784\u4f53,\u5176\u4e2dfbidx\u7b49\u4e8e\u6b21\u8bbe\u5907\u53f7id,\u663e\u7136\u8fd9\u4e2a\u6570\u7ec4\u5c31\u662f\u4fdd\u5b58\u6211\u4eec\u5404\u4e2alcd\u9a71\u52a8\u7684\u4fe1\u606f<\/span><\/p> \n 
2.2 fb_read\u51fd\u6570\u5982\u4e0b:<\/span><\/strong><\/p> \n 
 \n  
static<\/span> ssize_t fb_read(<\/span>struct<\/span> file *file, char<\/span> __user *buf, size_t count, loff_t *ppos)\r\n{\r\n       unsigned <\/span>long<\/span> p = *ppos;\r\n       <\/span>struct<\/span> inode *inode = file->f_path.dentry->d_inode; \r\n       <\/span>int<\/span> fbidx = iminor(inode);                       \/\/<\/span>\u83b7\u53d6\u6b21\u8bbe\u5907\u53f7<\/span>\r\n       struct<\/span> fb_info *info = registered_fb[fbidx];     \/\/<\/span>\u83b7\u53d6\u6b21\u8bbe\u5907\u53f7\u7684lcd\u9a71\u52a8\u7684\u4fe1\u606f<\/span>\r\n       u32 <\/span>*buffer, *dst;\r\n       u32 __iomem <\/span>*src;\r\n       <\/span>int<\/span> c, i, cnt = 0<\/span>, err = 0<\/span>;\r\n       unsigned <\/span>long<\/span> total_size;\r\n       ... ...\r\n       <\/span>if<\/span> (info->fbops->fb_read)\r\n              <\/span>return<\/span> info->fbops->fb_read(info, buf, count, ppos);\r\n     \r\n       total_size <\/span>= info->screen_size;     \/\/<\/span>\u83b7\u53d6\u5c4f\u5e55\u957f\u5ea6<\/span>\r\n    
       ... ...\r\n\r\n       buffer <\/span>= kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,GFP_KERNEL);    \/\/<\/span>\u5206\u914d\u7f13\u51b2\u533a       <\/span>\r\n       if<\/span> (!buffer)\r\n              <\/span>return<\/span> -ENOMEM;\r\n\r\n \r\n\r\n       src <\/span>= (u32 __iomem *) (info->screen_base + p);         \/\/<\/span>\u83b7\u53d6\u663e\u5b58\u7269\u7406\u57fa\u5730\u5740<\/span>\r\n       if<\/span> (info->fbops->fb_sync)\r\n              info<\/span>->fbops->fb_sync(info); \r\n\r\n       <\/span>while<\/span> (count) {\r\n              c  <\/span>= (count > PAGE_SIZE) ? PAGE_SIZE : count;   \/\/<\/span>\u83b7\u53d6\u9875\u5730\u5740<\/span>\r\n              dst <\/span>= buffer;\r\n\r\n<\/span>         \/*<\/span>\u56e0\u4e3asrc\u662f32\u4f4d,\u4e00\u4e2asrc\u7b49\u4e8e4\u4e2a\u5b57\u8282,\u6240\u4ee5\u9875\u5730\u5740c >> 2<\/span>*\/<\/span>\r\n              for<\/span> (i = c >> 2<\/span>; i--; )                     \r\n                     <\/span>*dst++ = fb_readl(src++);    \/\/<\/span>\u8bfb\u53d6\u663e\u5b58\u6bcf\u4e2a\u50cf\u7d20\u70b9\u6570\u636e,\u653e\u5230dst\u5730\u5740\u4e0a<\/span>\r\n\r\n              if<\/span> (c & 3<\/span>) {\r\n                     u8 <\/span>*dst8 = (u8 *) dst;\r\n                     u8 __iomem <\/span>*src8 = (u8 __iomem *) src;\r\n                     <\/span>for<\/span> (i = c & 3<\/span>; i--;)\r\n                            <\/span>*dst8++ = fb_readb(src8++);\r\n                     src <\/span>= (u32 __iomem *) src8;\r\n              }\r\n              <\/span>if<\/span> (copy_to_user(buf, buffer, c)) {  \/\/<\/span>\u4e0a\u4f20\u6570\u636e,\u957f\u5ea6\u7b49\u4e8e\u9875\u5730\u5740\u5927\u5c0f<\/span>\r\n                     err <\/span>= -EFAULT;\r\n                     <\/span>break<\/span>;\r\n              }\r\n              <\/span>*ppos += c;\r\n              buf <\/span>+= c;\r\n              cnt <\/span>+= c;\r\n              count <\/span>-= c;\r\n       }\r\n       kfree(buffer); \r\n       <\/span>return<\/span> (err) ? err : cnt;\r\n}<\/span><\/pre> \n <\/div> \n 
 <\/p> \n 
\u4ece.open\u548c.write\u51fd\u6570\u4e2d\u53ef\u4ee5\u53d1\u73b0,\u90fd\u4f9d\u8d56\u4e8efb_info\u5e27\u7f13\u51b2\u4fe1\u606f\u7ed3\u6784\u4f53,\u5b83\u4eceregistered_fb[fbidx]\u6570\u7ec4\u4e2d\u5f97\u5230,\u8fd9\u4e2a\u6570\u7ec4\u4fdd\u5b58\u6211\u4eec\u5404\u4e2alcd\u9a71\u52a8\u7684\u4fe1\u606f<\/span><\/p> \n 
3.\u6211\u4eec\u6765\u627e\u627e\u8fd9\u4e2a\u6570\u7ec4\u5728\u54ea\u91cc\u88ab\u6ce8\u518c,\u4f4d\u4e8eregister_framebuffer():<\/span><\/strong><\/p> \n 
 \n  
int<\/span> register_framebuffer(struct<\/span> fb_info *fb_info)\r\n{\r\n ... ...\r\n<\/span>for<\/span> (i = 0<\/span> ; i < FB_MAX; i++)    \/\/<\/span>\u67e5\u627e\u7a7a\u7684\u6570\u7ec4","orderid":"0","title":"15.linux-LCD\u5c42\u6b21\u5206\u6790(\u8be6\u89e3)(\u4e00)","smalltitle":"","mid":"0","fname":"\u5176\u5b83","special_id":"0","bak_id":"0","info":"0","hits":"6632","pages":"2","comments":"0","posttime":"2017-10-13 10:35:59","list":"1507862159","username":"admin","author":"","copyfrom":"","copyfromurl":"","titlecolor":"","fonttype":"0","titleicon":"0","picurl":"http:\/\/images2017.cnblogs.com\/blog\/1182576\/201709\/1182576-20170927182618450-1876645079.png","ispic":"1","yz":"1","yzer":"","yztime":"0","levels":"0","levelstime":"0","keywords":"15.linux-LCD<\/A> \u5c42\u6b21<\/A> \u5206\u6790<\/A> \u8be6\u89e3<\/A>","jumpurl":"","iframeurl":"","style":"","template":"a:3:{s:4:\"head\";s:0:\"\";s:4:\"foot\";s:0:\"\";s:8:\"bencandy\";s:0:\"\";}","target":"0","ip":"113.108.110.181","lastfid":"0","money":"0","buyuser":"","passwd":"","allowdown":"","allowview":"","editer":"","edittime":"0","begintime":"0","endtime":"0","description":"15.linux-LCD\u5c42\u6b21\u5206\u6790(\u8be6\u89e3)","lastview":"1713513879","digg_num":"1775","digg_time":"0","forbidcomment":"0","ifvote":"0","heart":"","htmlname":"","city_id":"0"},"page":"1"}