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概述 bus 模块的功能包括: bus 的注册和注销 本 bus 下有 device 或者 device_driver 注册到内核时的处理 本 bus 下有 device 或者 device_driver 从内核注销时的处理 device_drivers 的 probe 处理 管理 bus 下的所有 device 和 device_driver 数据结构 struct bus_type { const char *name; const char *dev_name; const struct attribute_group **bus_groups; const struct attribute_group **dev_groups; const struct attribute_group **drv_groups; int (*match)(struct device *dev, struct device_driver *drv); int (*uevent)(const struct device *dev, struct kobj_uevent_env *env); int (*probe)(struct device *dev); void (*sync_state)(struct device *dev); void (*remove)(struct device *dev); void (*shutdown)(struct device *dev); int (*online)(struct device *dev); int (*offline)(struct device *dev); int (*suspend)(struct device *dev, pm_message_t state); int (*resume)(struct device *dev); int (*num_vf)(struct device *dev); int (*dma_configure)(struct device *dev); void (*dma_cleanup)(struct device *dev); const struct dev_pm_ops *pm; bool need_parent_lock; }; name : bus 的名称....

2 min

struct device { struct kobject kobj; struct device *parent; struct device_private *p; const char *init_name; /* initial name of the device */ const struct device_type *type; const struct bus_type *bus; /* type of bus device is on */ struct device_driver *driver; /* which driver has allocated this device */ void *platform_data; /* Platform specific data, device core doesn't touch it */ void *driver_data; /* Driver data, set and get with dev_set_drvdata/dev_get_drvdata */ struct mutex mutex; /* mutex to synchronize calls to * its driver....

2 min

数据结构 Platform 设备是可以通过 CPU bus 直接寻址的设备, 内核在设备模型 bus, device 和 driver 的基础上, 进行了进一步封装, 抽象了 platform_bus, platform_device, platform_driver. platform 相关的实现在 include/linux/platform_device.h, drivers/base/platform.c中. struct platform_device { const char *name; int id; bool id_auto; struct device dev; u64 platform_dma_mask; struct device_dma_parameters dma_parms; u32 num_resources; struct resource *resource; const struct platform_device_id *id_entry; }; name: platform device 的名称. dev: 指向底层的 device. id: 可以手动设置, 也可设置为宏 PLATFORM_DEVID_NONE 表示没有 id, pdev->dev->name 直接设置为 pdev->name. 设置为宏 PLATFORM_DEVID_AUTO 表示自动生成 id. id_auto: 当 id 设置为 PLATFORM_DEVID_AUTO, id_auto 被置为 true, 在注册 platform_device 时可以自动生成 id....

2 min

概述 include/linux/kobject.h lib/kobject.c Kobject 是基本数据类型，每个 Kobject 都会在"/sys/“文件系统中以目录的形式出现。 Ktype 代表 Kobject 的属性操作集合 (由于通用性，多个 Kobject 可能共用同一个属性操作集，因此把 Ktype 独立出来了). Kset 是一个特殊的 Kobject（因此它也会在"/sys/“文件系统中以目录的形式出现），它用来集合相似的 Kobject（这些 Kobject 可以是相同属性的，也可以不同属性的）。 数据结构 kobject: struct kobject { const char *name; struct list_head entry; struct kobject *parent; struct kset *kset; const struct kobj_type *ktype; struct kernfs_node *sd; /* sysfs directory entry */ struct kref kref; unsigned int state_initialized:1; unsigned int state_in_sysfs:1; unsigned int state_add_uevent_sent:1; unsigned int state_remove_uevent_sent:1; unsigned int uevent_suppress:1; }; name: kobject 的名称, 也是在 sysfs 中的目录名....

2 min

kernel boot 过程，设备树初始化 reserved-memory 节点： early_init_fdt_scan_reserved_mem() fdt_scan_reserved_mem(); fdt_init_reserved_mem(); static int __init fdt_scan_reserved_mem(void) { int node, child; const void *fdt = initial_boot_params; node = fdt_path_offset(fdt, "/reserved-memory"); fdt_for_each_subnode(child, fdt, node) { const char *uname; int err; if (!of_fdt_device_is_available(fdt, child)) continue; uname = fdt_get_name(fdt, child, NULL); /// 存在 reg 属性的情况 err = __reserved_mem_reserve_reg(child, uname); /// 不存在 reg 属性的情况，存在 size 属性 if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) fdt_reserved_mem_save_node(child, uname, 0, 0); } return 0; } /// 先预留 rmem 的 base 和 size 都为 0 void __init fdt_reserved_mem_save_node(unsigned long node, const char *uname, phys_addr_t base, phys_addr_t size) { struct reserved_mem *rmem = &reserved_mem[reserved_mem_count]; rmem->fdt_node = node; rmem->name = uname; rmem->base = base; rmem->size = size; reserved_mem_count++; return; } void __init fdt_init_reserved_mem(void) { int i; for (i = 0; i < reserved_mem_count; i++) { struct reserved_mem *rmem = &reserved_mem[i]; unsigned long node = rmem->fdt_node; int len; const __be32 *prop; int err = 0; bool nomap; nomap = of_get_flat_dt_prop(node, "no-map", NULL) !...

3 min

Data Structure struct software_node { const char *name; const struct software_node *parent; const struct property_entry *properties; }; struct swnode { struct kobject kobj; struct fwnode_handle fwnode; const struct software_node *node; int id; /* hierarchy */ struct ida child_ids; struct list_head entry; struct list_head children; struct swnode *parent; unsigned int allocated:1; unsigned int managed:1; }; Provider software_node_register()注册单个 software node, software_node_register_node_group()注册一组 software nodes. 都是将 software nodes 挂入一个全局链表. // 定义属性 static const struct property_entry my_device_properties[] = { PROPERTY_ENTRY_U32("reg", 0), PROPERTY_ENTRY_U32("my_property", 1234), { } }; // 定义 software node static const struct software_node my_device_node = { ....

2 min

v4l2-async.c v4l2-common.h v4l_err()/v4l_warn()/v4l_info()/v4l_dbg(); // for v4l-i2c drivers v4l2_err()/v4l2_warn()/v4l2_info()/v4l2_dbg(); // for v4l2_device and v4l2_subdev // v4l2_ctrl_query_fill(); // v4l2_i2c_new_subdev(); v4l2_i2c_subdev_set_name(); v4l2-ctl.h v4l2-dev.h v4l2_prio_init(); v4l2_prio_change(); v4l2_prio_open(); v4l2_prio_close(); v4l2_prio_max(); v4l2_prio_check(); media_entity_to_video_device(); // to_video_device(); > video_register_device();/video_unregister_device(); // video_register_device_no_warn(); > video_device_alloc();/video_device_release(); > video_device_release_empty(); > v4l2_disable_ioctl(); > video_get_drvdata();/video_set_drvdata(); // get/set video device private data > video_devdata(); // 获取 file 对应的 video device > video_drvdata(); // video_get_drvdata()); > video_device_node_name(); // 获取 device name > video_is_registered(); // 检查 video device 是否已经注册 > video_device_pipeline_start();__video_device_pipeline_start(); > video_device_pipeline_stop();__video_device_pipeline_stop(); > video_device_pipeline_alloc_start(); // 多了 allocate pipeline 的操作，不过一般 pipeline 会嵌在 driver 自定义结构体中，随着上层一起分配。 // video_device_pipeline(); v4l2-device....

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IPCam 3917 isp 模块图: 信号处理路径模块： Crop：裁剪模块，用于裁剪图像的特定区域 BLC：黑电平补偿(Black level Correction) DPC: 坏点校正(Defect Pixel Correction) 2DNR: 2D降噪(2D Noise Reduction) GE: 边缘增强(Gain Enhancement) 3DNR & GE：3D降噪和增益增强 AE Short/Long Gain：自动曝光短/长时间增益控制 HDR Fusion：高动态范围图像融合，合并不同曝光的图像 镜头校正模块： Circle Lens Shading：圆形镜头阴影校正 Grid Lens Shading：网格镜头阴影校正 色彩处理模块： YUV to RGB：YUV色彩空间转换为RGB INTP：demosaic颜色插值, 从raw格式转换到rgb格式 CCM：色彩校正矩阵(Color Correction Matrix) RGB Gamma：RGB伽马校正 WDR：宽动态范围(Wide Dynamic Range)处理 YUV处理模块： YUV420 To YUV422：YUV色彩格式转换 YUV422 To YUV444：YUV色彩格式转换 RGB2YUV444：RGB转YUV444格式 Global Curve：全局曲线调整 UV Tune & UVS：UV通道调整和UV抑制 统计和分析模块： AF Statistics：自动对焦统计数据 AE Short/Long Statistics：自动曝光短/长时间统计数据 Raw Statistics：原始图像统计数据...

1 min

libisp api: global api: rts_av_isp_init/cleanup rts_av_isp_start/stop rts_av_isp_get_status rts_av_isp_register/unregister/get_algo rts_av_isp_bind/unbind_algo rts_av_isp_register/unregister/get/check_sensor rts_av_isp_bind/unbind_sensor rts_av_isp_register_iq mipi out api: rts_av_isp_set_mipiout rts_av_isp_get_mipiout v4l2 control: rts_isp_v4l2_query_ctrl rts_isp_v4l2_query_menu rts_isp_v4l2_g_ctrl rts_isp_v4l2_s_ctrl rts_isp_v4l2_query_ext_ctrl rts_isp_v4l2_g_ext_ctrls rts_isp_v4l2_s_ext_ctrls rts_isp_v4l2_try_ext_ctrls sensor: private mask: 3A Setting: 3A Statis: IQ tuning: other: struct isp_core { struct isp_mod_hash_table hash; struct isp_notify notify; struct v4l2_ctrl_handler ctrl_handler; struct isp_statis statis; struct isp_iq iq; int initialized:1; int running:1; }; hash: hash table, 用来保存 modules. notify: ctrl_hander: statis: iq: initialized: isp_core_init() 之后置 1....

2 min

Chapter 2 Terminology Lane: 单向物理传输 lane, 2(D-PHY) or 3(C-PHY) wire interface for clock or data transmission. Virtual channel: 逻辑层面的概念，每个虚拟通道的数据彼此独立，在 lane 上交错发送，包含标识信息，指明属于哪个外设/通道。 Chapter 7 Physical Layer 有两种 physical layer，D-PHY 和 C-PHY, transmitter 和 receiver 需要一致。 7.1 D-PHY Physical Layer option D-PHY 由多条单向的 data lanes 和一条 clk lane。 对于 clk lane, transmitter 和 receiver 必须实现 continuous clock，non-continuous clock 是可选的。 continuous clk: 保持在 high-speed mode. non-continuous clk: 在两笔数据包之间进入 LP-11 state. 7.2 C-PHY Physical Layer option Chapter 9 Low Level Protocol Features:...

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