linux显卡驱动之fb_ops

fb_ops是fb_info结构体中的一个重要成员变量

原型定义在linux/fb.h文件中，定义如下：

/*
 * Frame buffer operations
 *
 * LOCKING NOTE: those functions must _ALL_ be called with the console
 * semaphore held, this is the only suitable locking mechanism we have
 * in 2.6. Some may be called at interrupt time at this point though.
 *
 * The exception to this is the debug related hooks.  Putting the fb
 * into a debug state (e.g. flipping to the kernel console) and restoring
 * it must be done in a lock-free manner, so low level drivers should
 * keep track of the initial console (if applicable) and may need to
 * perform direct, unlocked hardware writes in these hooks.
 */

struct fb_ops {
	/* open/release and usage marking */
	struct module *owner;
	int (*fb_open)(struct fb_info *info, int user);
	int (*fb_release)(struct fb_info *info, int user);

	/* For framebuffers with strange non linear layouts or that do not
	 * work with normal memory mapped access
	 */
	ssize_t (*fb_read)(struct fb_info *info, char __user *buf,
			   size_t count, loff_t *ppos);
	ssize_t (*fb_write)(struct fb_info *info, const char __user *buf,
			    size_t count, loff_t *ppos);

	/* checks var and eventually tweaks it to something supported,
	 * DO NOT MODIFY PAR */
	int (*fb_check_var)(struct fb_var_screeninfo *var, struct fb_info *info);

	/* set the video mode according to info->var */
	int (*fb_set_par)(struct fb_info *info);

	/* set color register */
	int (*fb_setcolreg)(unsigned regno, unsigned red, unsigned green,
			    unsigned blue, unsigned transp, struct fb_info *info);

	/* set color registers in batch */
	int (*fb_setcmap)(struct fb_cmap *cmap, struct fb_info *info);

	/* blank display */
	int (*fb_blank)(int blank, struct fb_info *info);

	/* pan display */
	int (*fb_pan_display)(struct fb_var_screeninfo *var, struct fb_info *info);

	/* Draws a rectangle */
	void (*fb_fillrect) (struct fb_info *info, const struct fb_fillrect *rect);
	/* Copy data from area to another */
	void (*fb_copyarea) (struct fb_info *info, const struct fb_copyarea *region);
	/* Draws a image to the display */
	void (*fb_imageblit) (struct fb_info *info, const struct fb_image *image);

	/* Draws cursor */
	int (*fb_cursor) (struct fb_info *info, struct fb_cursor *cursor);

	/* Rotates the display */
	void (*fb_rotate)(struct fb_info *info, int angle);

	/* wait for blit idle, optional */
	int (*fb_sync)(struct fb_info *info);

	/* perform fb specific ioctl (optional) */
	int (*fb_ioctl)(struct fb_info *info, unsigned int cmd,
			unsigned long arg);

	/* Handle 32bit compat ioctl (optional) */
	int (*fb_compat_ioctl)(struct fb_info *info, unsigned cmd,
			unsigned long arg);

	/* perform fb specific mmap */
	int (*fb_mmap)(struct fb_info *info, struct vm_area_struct *vma);

	/* get capability given var */
	void (*fb_get_caps)(struct fb_info *info, struct fb_blit_caps *caps,
			    struct fb_var_screeninfo *var);

	/* teardown any resources to do with this framebuffer */
	void (*fb_destroy)(struct fb_info *info);

	/* called at KDB enter and leave time to prepare the console */
	int (*fb_debug_enter)(struct fb_info *info);
	int (*fb_debug_leave)(struct fb_info *info);
};

经过实际测试，我将我的测试结果和总结写出来，供其他人参考。

最简洁fb_ops：

struct fb_ops s3cfb_ops = {
    .fb_set_par	= s3cfb_set_par,
    .fb_setcolreg	= s3cfb_setcolreg,
    .fb_imageblit	= cfb_imageblit,
};

这样定义后，就可以在内核启动时出现久违的企鹅图像。

最后

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