第18章LCD设备驱动之Linux 帧缓冲设备驱动的fb_ops成员函数

最新推荐文章于 2024-08-09 23:57:02 发布

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最新推荐文章于 2024-08-09 23:57:02 发布 · 2.3k 阅读

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18.7 Linux 帧缓冲设备驱动的fb_ops成员函数

fb_info 中的 fp_ops 是使得帧缓冲设备工作所需函数的集合，它们最终与 LCD 控制器硬件打交道。

fb_check_var()用于调整可变参数，并修正为硬件所支持的值；fb_set_par()根据屏幕参数设置具体读写 LCD 控制器的寄存器以使得 LCD 控制器进入相应的工作状态。对于 fb_ops 中的 fb_fillrect()、fb_copyarea()和 fb_imageblit()成员函数，通常直接使用对应的通用的 cfb_fillrect() 、 cfb_copyarea() 和 cfb_imageblit() 函数即可。

cfb_fillrect() 函数定义在drivers/video/fbdev/core/cfbfillrect.c文件中

void cfb_fillrect(struct fb_info *p, const struct fb_fillrect *rect)
{
unsigned long pat, pat2, fg;
unsigned long width = rect->width, height = rect->height;
int bits = BITS_PER_LONG, bytes = bits >> 3;
u32 bpp = p->var.bits_per_pixel;
unsigned long __iomem *dst;
int dst_idx, left;

if (p->state != FBINFO_STATE_RUNNING)
return;

if (p->fix.visual == FB_VISUAL_TRUECOLOR ||
p->fix.visual == FB_VISUAL_DIRECTCOLOR )
fg = ((u32 *) (p->pseudo_palette))[rect->color];
else
fg = rect->color;

pat = pixel_to_pat(bpp, fg);

dst = (unsigned long __iomem *)((unsigned long)p->screen_base & ~(bytes-1));
dst_idx = ((unsigned long)p->screen_base & (bytes - 1))*8;
dst_idx += rect->dy*p->fix.line_length*8+rect->dx*bpp;
/* FIXME For now we support 1-32 bpp only */
left = bits % bpp;
if (p->fbops->fb_sync)
p->fbops->fb_sync(p);
if (!left) {
u32 bswapmask = fb_compute_bswapmask(p);
void (*fill_op32)(struct fb_info *p,
unsigned long __iomem *dst, int dst_idx,
unsigned long pat, unsigned n, int bits,
u32 bswapmask) = NULL;

switch (rect->rop) {
case ROP_XOR:
fill_op32 = bitfill_aligned_rev;
break;
case ROP_COPY:
fill_op32 = bitfill_aligned;
break;
default:
printk( KERN_ERR "cfb_fillrect(): unknown rop, defaulting to ROP_COPY\n");
&nb