2023年6月26日发(作者：)

linux驱动编写（摄像头驱动）【 声明：版权所有，欢迎转载，请勿⽤于商业⽤途。 联系信箱：feixiaoxing @】

对于现代嵌⼊式设备，特别是⼿机来说，摄像头是很重要的⼀个设备。很多同学买⼿机，⼀看颜值，第⼆就看摄像头拍照如何。所以，从某个⾓度来说，摄像头是各个⼚家主打的应⽤功能。那么，linux是如何⽀持摄像头的，我们可以来看⼀下？

1、代码⽬录地址drivers/media

2、v4l2框架⽬前linux上的camera都是按照v4l2框架来设计，它的地址位于drivers/media/v4l2-core

3、查看三星soc是如何⽀持camera的，可以查看drviers/media/platform/Kconfigconfig VIDEO_S3C_CAMIF tristate "Samsung S3C24XX/S3C64XX SoC Camera Interface driver" depends on VIDEO_V4L2 && I2C && VIDEO_V4L2_SUBDEV_API depends on PM depends on ARCH_S3C64XX || PLAT_S3C24XX || COMPILE_TEST depends on HAS_DMA select VIDEOBUF2_DMA_CONTIG ---help--- This is a v4l2 driver for s3c24xx and s3c64xx SoC series camera host interface (CAMIF). To compile this driver as a module, choose M here: the module will be called s3c-camif.

4、从Kconfig确认除了VIDEO_V4L2和VIDEO_V4L2_SUBDEV_API之外，它只依赖⾃⼰的⽬录obj-$(CONFIG_VIDEO_S3C_CAMIF) += s3c-camif/

5、继续查看s3c-camif⽬录的代码结构# Makefile for s3c244x/s3c64xx CAMIF drivers3c-camif-objs := camif-core.o camif-capture.o -$(CONFIG_VIDEO_S3C_CAMIF) += s3c-camif.o

6、Makefile说的很清楚，它主要依赖camif-*.c三个⽂件 通过阅读，确认camif-core.c是注册⽂件camif-regs.c是寄存器读写⽂件camif-capture.c是主要的操作⽂件、接⼝⽂件

7、确认v4l2的函数操作接⼝static const struct v4l2_ioctl_ops s3c_camif_ioctl_ops = { .vidioc_querycap = s3c_camif_vidioc_querycap, .vidioc_enum_input = s3c_camif_vidioc_enum_input, .vidioc_g_input = s3c_camif_vidioc_g_input, .vidioc_s_input = s3c_camif_vidioc_s_input, .vidioc_enum_fmt_vid_cap = s3c_camif_vidioc_enum_fmt, .vidioc_try_fmt_vid_cap = s3c_camif_vidioc_try_fmt, .vidioc_s_fmt_vid_cap = s3c_camif_vidioc_s_fmt, .vidioc_g_fmt_vid_cap = s3c_camif_vidioc_g_fmt, .vidioc_g_selection = s3c_camif_g_selection, .vidioc_s_selection = s3c_camif_s_selection, .vidioc_reqbufs = s3c_camif_reqbufs, .vidioc_querybuf = s3c_camif_querybuf, .vidioc_prepare_buf = s3c_camif_prepare_buf, .vidioc_create_bufs = s3c_camif_create_bufs, .vidioc_qbuf = s3c_camif_qbuf, .vidioc_dqbuf = s3c_camif_dqbuf, .vidioc_streamon = s3c_camif_streamon, .vidioc_streamoff = s3c_camif_streamoff, .vidioc_subscribe_event = v4l2_ctrl_subscribe_event, .vidioc_unsubscribe_event = v4l2_event_unsubscribe, .vidioc_log_status = v4l2_ctrl_log_status,};and static const struct v4l2_file_operations s3c_camif_fops = { .owner = THIS_MODULE, .open = s3c_camif_open, .release = s3c_camif_close, .poll = s3c_camif_poll, .unlocked_ioctl = video_ioctl2, .mmap = s3c_camif_mmap, };static const struct vb2_ops s3c_camif_qops = { .queue_setup = queue_setup, .buf_prepare = buffer_prepare, .buf_queue = buffer_queue, .wait_prepare = vb2_ops_wait_prepare, .wait_finish = vb2_ops_wait_finish, .start_streaming = start_streaming, .stop_streaming = stop_streaming,};const struct vb2_mem_ops vb2_dma_contig_memops = { .alloc = vb2_dc_alloc, .put = vb2_dc_put, .get_dmabuf = vb2_dc_get_dmabuf, .cookie = vb2_dc_cookie, .vaddr = vb2_dc_vaddr, .mmap = vb2_dc_mmap, .get_userptr = vb2_dc_get_userptr, .put_userptr = vb2_dc_put_userptr, .prepare = vb2_dc_prepare, .finish = vb2_dc_finish, .map_dmabuf = vb2_dc_map_dmabuf, .unmap_dmabuf = vb2_dc_unmap_dmabuf, .attach_dmabuf = vb2_dc_attach_dmabuf, .detach_dmabuf = vb2_dc_detach_dmabuf, .num_users = vb2_dc_num_users,};

8、和sd⼀样，接⼝⽐较简单，但是要深⼊了解camera，v4l2是绕不过去的。这⼀点和sd卡、usb、asoc是⼀样的。