新路程------imx6 lvds ioctl

最近有个需求，做一些接口给上层应用调用

于是看了一下驱动，linux有一套标准的framebuffer机制让我们做接口，就是fb_ioctl

首先看对应的framebuffer驱动，在之前的ldb.c中，确实配置了对应的fb_info结构体，但是要修改这个结构体的参数并不需要在ldb.c中做，在mxc_ipuv3_fb.c里

static struct fb_ops mxcfb_ops = {.owner = THIS_MODULE,.fb_set_par = mxcfb_set_par,.fb_check_var = mxcfb_check_var,.fb_setcolreg = mxcfb_setcolreg,.fb_pan_display = mxcfb_pan_display,.fb_ioctl = mxcfb_ioctl,.fb_mmap = mxcfb_mmap,.fb_fillrect = cfb_fillrect,.fb_copyarea = cfb_copyarea,.fb_imageblit = cfb_imageblit,.fb_blank = mxcfb_blank,};

这里实现了自己特定的

fb_ioctl 

看看有哪些现成的cmd

/* * Function to handle custom ioctls for MXC framebuffer. * * @param       inode   inode struct * * @param       file    file struct * * @param       cmd     Ioctl command to handle * * @param       arg     User pointer to command arguments * * @param       fbi     framebuffer information pointer */static int mxcfb_ioctl(struct fb_info *fbi, unsigned int cmd, unsigned long arg)  //上层调用的时候就会把fbi也就是/dev/fb0之类的参数传入，arg是要写入的数据的首地址{int retval = 0;int __user *argp = (void __user *)arg;struct mxcfb_info *mxc_fbi = (struct mxcfb_info *)fbi->par;//fbi是linux通用标准结构体，但是不同的ic需要自己特定的framebuffer结构体//add by matthew_xuan int matt_bpp=0; int matt_res[2]=0; // struct fb_var_screeninfo *matt_var=fbi->var;//switch (cmd) {case MXCFB_SET_LOC_ALPHA:{struct mxcfb_loc_alpha la;if (copy_from_user(&la, (void *)arg, sizeof(la))) { //获取传入的设置数据retval = -EFAULT;break;}if (ipu_disp_set_global_alpha(mxc_fbi->ipu, mxc_fbi->ipu_ch,  //这个ipu：整个IPU挂接在AXI与AHB总线上面，通过总线，它可以与ARM，VPU，GPU和RAM等模块通信。//通过LDB控制到LVDS屏，直接控制LCD屏，并且可以通过HDMI或者MIPI来显示。      !(bool)la.enable, 0)) {retval = -EINVAL;break;}if (la.enable && !la.alpha_in_pixel) {struct fb_info *fbi_tmp;ipu_channel_t ipu_ch;mxc_fbi->alpha_chan_en = true;if (mxc_fbi->ipu_ch == MEM_FG_SYNC)ipu_ch = MEM_BG_SYNC;else if (mxc_fbi->ipu_ch == MEM_BG_SYNC)ipu_ch = MEM_FG_SYNC;else {retval = -EINVAL;break;}fbi_tmp = found_registered_fb(ipu_ch, mxc_fbi->ipu_id);if (fbi_tmp)((struct mxcfb_info *)(fbi_tmp->par))->alpha_chan_en = false;} elsemxc_fbi->alpha_chan_en = false;fbi->var.activate = (fbi->var.activate & ~FB_ACTIVATE_MASK) |FB_ACTIVATE_NOW | FB_ACTIVATE_FORCE;mxcfb_set_par(fbi);  //这里把新设置的fbi参数传给notifier去处理la.alpha_phy_addr0 = mxc_fbi->alpha_phy_addr0;la.alpha_phy_addr1 = mxc_fbi->alpha_phy_addr1;if (copy_to_user((void *)arg, &la, sizeof(la))) {retval = -EFAULT;break;}if (la.enable)dev_dbg(fbi->device,"Enable DP local alpha for %s\n",fbi->fix.id);break;}case MXCFB_GET_FB_BLANK:{struct mxcfb_info *mxc_fbi =(struct mxcfb_info *)fbi->par;if (put_user(mxc_fbi->cur_blank, argp))return -EFAULT;break;}case MXCFB_SET_DIFMT:{struct mxcfb_info *mxc_fbi =(struct mxcfb_info *)fbi->par;if (get_user(mxc_fbi->ipu_di_pix_fmt, argp))return -EFAULT;break;}//add by matthew_xuancase MXCFB_SET_XRES_YRES:{if (copy_from_user(&matt_res, (void *)arg, sizeof(matt_res))) {retval = -EFAULT;break;}fbi->var->xres=matt_res[0];fbi->var->yres=matt_res[1];mxcfb_set_par(fbi);}default:retval = -EINVAL;}return retval;}

这里的
#define MXCFB_CSC_UPDATE _IOW('F', 0x2D, struct mxcfb_csc_matrix)
//add by matthew_xuan
#define MXCFB_SET_XRES_YRES   _IOW('F', 0x2E, int struct mxcfb_matt_res)
可以参考这篇文章  http://blog.chinaunix.net/uid-20754793-id-177774.html
接下来看
static int mxcfb_set_par(struct fb_info *fbi)
{
mxcfb_set_fix(fbi);设置了fix结构体
_setup_disp_channel1(fbi); 重新定义输出屏幕的格式
_setup_disp_channel1(fbi);这里启动之后，上层应用调用输出才会成功
}
再看看
static int _setup_disp_channel2(struct fb_info *fbi)
{
retval = ipu_init_channel_buffer(mxc_fbi->ipu,
mxc_fbi->ipu_ch, IPU_INPUT_BUFFER,
fbi_to_pixfmt(fbi),
fbi->var.xres, fbi->var.yres,
fb_stride,
fbi->var.rotate,
base,
base,
fbi->var.accel_flags &
FB_ACCEL_DOUBLE_FLAG ? 0 : base,
0, 0);
}
整个大概的过程就是这样哦