update doc

README.md

@@ -8,16 +8,23 @@ scp -r name@ip:GIT_ROOT/linux/out/_modules/lib/modules/linuxxxx/extra .
 ### kgdb
 patch: patches/kdb_arm64.patch
 config: patches/kdb_config.diff
-1. [arm64 kgdb1](https://blog.csdn.net/qq_35712169/article/details/108217641) [arm64 kgdb2](https://zhuanlan.zhihu.com/p/197545583)
+1. [arm64 kgdb1](https://blog.csdn.net/qq_35712169/article/details/108217641) [arm64 kgdb2](https://zhuanlan.zhihu.com/p/197545583)  
 
 ### earlycon
-1. [earlycon](https://blog.csdn.net/ooonebook/article/details/52654191)
+1. [earlycon](https://blog.csdn.net/ooonebook/article/details/52654191)  
 
 
-### [device tree](./doc/devicetree_cn.md)
+### [device tree](./doc/devicetree_cn.md)  
+### [softirq tasklet](./doc/softirq_cn.md)  
+### [rwsem-读写信号量](./doc/rwsem_cn.md)
 
 #### 参考：
 [Linux内核中的pinctrl子系统应用实例](https://blog.csdn.net/u012719256/article/details/76070339)  
-[Linux - 使用V4L2（总结）](https://blog.csdn.net/weixin_43707799/article/details/107821189)  
-[Linux V4L2之camera](https://www.cnblogs.com/vedic/p/10763838.html)  
-[深入学习Linux摄像头（二）v4l2驱动框架](https://blog.csdn.net/weixin_42462202/article/details/99680969)
+[一文让你读懂Linux五大模块内核源码，内核整体架构设计（超详细）](https://zhuanlan.zhihu.com/p/474337723)  
+[linux系统调度之时间](https://blog.csdn.net/eleven_xiy/article/details/71175347)  
+
+[mtk linux](https://gitlab.com/mediatek/aiot/bsp/linux)  
+
+### 面试题
+[知乎1](https://zhuanlan.zhihu.com/p/161100568)  
+[Linux内核知识点---线程、锁、中断下半部、定时器](https://blog.csdn.net/baidu_19348579/article/details/126222242)  

doc/devicetree_cn.md

@@ -8,3 +8,214 @@
 [设备树处理之——device_node转换成platform_device](https://www.cnblogs.com/downey-blog/p/10486568.html)  
 [Linux 驱动开发 十六：设备树在系统中的体现 1](https://blog.csdn.net/OnlyLove_/article/details/121987183)  
 [Linux 驱动开发 十六：设备树在系统中的体现 2](https://www.cnblogs.com/multimicro/p/11905647.html)  
+
+## devicetree加载resource流程
+of_platform_sync_state_init -> of_platform_default_populate -> of_platform_populate -> of_platform_bus_create -> of_platform_device_create_pdata ->  
+
+
+of_platform_sync_state_init -> 
+```c
+// drivers/of/platform.c
+
+static int __init of_platform_default_populate_init(void)
+{
+	struct device_node *node;
+
+	device_links_supplier_sync_state_pause();
+
+	if (!of_have_populated_dt())
+		return -ENODEV;
+
+	if (IS_ENABLED(CONFIG_PPC)) {
+		...
+	} else {
+		...
+		/* Populate everything else. */
+		of_platform_default_populate(NULL, NULL, NULL);
+	}
+
+	return 0;
+}
+arch_initcall_sync(of_platform_default_populate_init);
+
+```
+
+of_platform_default_populate ->
+```c
+// drivers/of/platform.c
+int of_platform_default_populate(struct device_node *root, const struct of_dev_auxdata *lookup, struct device *parent)
+{
+	return of_platform_populate(root, of_default_bus_match_table, lookup, parent);
+}
+
+```
+
+of_platform_populate -> of_platform_bus_create
+```c
+// drivers/of/platform.c
+int of_platform_populate(struct device_node *root, const struct of_device_id *matches, const struct of_dev_auxdata *lookup, struct device *parent)
+{
+	struct device_node *child;
+	int rc = 0;
+
+	root = root ? of_node_get(root) : of_find_node_by_path("/");
+	if (!root)
+		return -EINVAL;
+
+	pr_debug("%s()\n", __func__);
+	pr_debug(" starting at: %pOF\n", root);
+
+	device_links_supplier_sync_state_pause();
+	for_each_child_of_node(root, child) {
+		rc = of_platform_bus_create(child, matches, lookup, parent, true);
+		if (rc) {
+			of_node_put(child);
+			break;
+		}
+	}
+	device_links_supplier_sync_state_resume();
+
+	of_node_set_flag(root, OF_POPULATED_BUS);
+
+	of_node_put(root);
+	return rc;
+}
+```
+
+of_platform_bus_create -> of_platform_device_create_pdata
+```c
+// drivers/of/platform.c
+static int of_platform_bus_create(struct device_node *bus,
+				  const struct of_device_id *matches,
+				  const struct of_dev_auxdata *lookup,
+				  struct device *parent, bool strict)
+{
+	const struct of_dev_auxdata *auxdata;
+	struct device_node *child;
+	struct platform_device *dev;
+	const char *bus_id = NULL;
+	void *platform_data = NULL;
+	int rc = 0;
+
+	...
+	dev = of_platform_device_create_pdata(bus, bus_id, platform_data, parent);
+	if (!dev || !of_match_node(matches, bus))
+		return 0;
+
+	for_each_child_of_node(bus, child) {
+		pr_debug("   create child: %pOF\n", child);
+		rc = of_platform_bus_create(child, matches, lookup, &dev->dev, strict);
+		if (rc) {
+			of_node_put(child);
+			break;
+		}
+	}
+	of_node_set_flag(bus, OF_POPULATED_BUS);
+	return rc;
+}
+```
+of_platform_device_create_pdata -> of_device_alloc
+```c
+// drivers/of/platform.c
+struct platform_device *of_device_alloc(struct device_node *np, const char *bus_id, struct device *parent)
+{
+	struct platform_device *dev;
+	int rc, i, num_reg = 0;
+	struct resource *res, temp_res;
+
+	dev = platform_device_alloc("", PLATFORM_DEVID_NONE);
+	if (!dev)
+		return NULL;
+
+	/* count the io resources */
+	while (of_address_to_resource(np, num_reg, &temp_res) == 0)
+		num_reg++;
+
+	/* Populate the resource table */
+	if (num_reg) {
+		res = kcalloc(num_reg, sizeof(*res), GFP_KERNEL);
+		if (!res) {
+			platform_device_put(dev);
+			return NULL;
+		}
+
+		dev->num_resources = num_reg;
+		dev->resource = res;
+		for (i = 0; i < num_reg; i++, res++) {
+			rc = of_address_to_resource(np, i, res);
+			WARN_ON(rc);
+		}
+	}
+
+	dev->dev.of_node = of_node_get(np);
+	dev->dev.fwnode = &np->fwnode;
+	dev->dev.parent = parent ? : &platform_bus;
+
+	if (bus_id)
+		dev_set_name(&dev->dev, "%s", bus_id);
+	else
+		of_device_make_bus_id(&dev->dev);
+
+	return dev;
+}
+```
+of_address_to_resource
+```c
+// drivers/of/address.c
+int of_address_to_resource(struct device_node *dev, int index,
+			   struct resource *r)
+{
+	return __of_address_to_resource(dev, index, -1, r);
+}
+
+static int __of_address_to_resource(struct device_node *dev, int index, int bar_no,
+		struct resource *r)
+{
+	u64 taddr;
+	const __be32	*addrp;
+	u64		size;
+	unsigned int	flags;
+	const char	*name = NULL;
+
+	addrp = __of_get_address(dev, index, bar_no, &size, &flags);
+	if (addrp == NULL)
+		return -EINVAL;
+
+	/* Get optional "reg-names" property to add a name to a resource */
+	if (index >= 0)
+		of_property_read_string_index(dev, "reg-names",	index, &name);
+
+	if (flags & IORESOURCE_MEM)
+		taddr = of_translate_address(dev, addrp);
+	else if (flags & IORESOURCE_IO)
+		taddr = of_translate_ioport(dev, addrp, size);
+	else
+		return -EINVAL;
+
+	if (taddr == OF_BAD_ADDR)
+		return -EINVAL;
+	memset(r, 0, sizeof(struct resource));
+
+	if (of_mmio_is_nonposted(dev))
+		flags |= IORESOURCE_MEM_NONPOSTED;
+
+	r->start = taddr;
+	r->end = taddr + size - 1;
+	r->flags = flags;
+	r->name = name ? name : dev->full_name;
+
+	return 0;
+}
+```
+
+
+
+
+
+
+
+
+
+
+
+

doc/rwsem_cn.md

@@ -0,0 +1,6 @@
+code: kernel/locking/rwsem.c
+
+##参考
+
+* [深入讲解读写信号量（上）](https://zhuanlan.zhihu.com/p/578510398)  
+* [深入讲解读写信号量（下）](https://zhuanlan.zhihu.com/p/578543055)  

doc/softirq_cn.md

@@ -0,0 +1,10 @@
+
+
+## 参考
+
+[Linux内核中的下半部机制之tasklet](https://zhuanlan.zhihu.com/p/88746106)  
+[linux网络软中断softirq底层机制及并发优化](https://developer.aliyun.com/article/557121)  
+[linux 下半部机制 - softirq使用](https://zhuanlan.zhihu.com/p/363245257)  
+[Linux内核中断处理“下半部”机制（上）（超详细~）](https://zhuanlan.zhihu.com/p/510834583)  
+[Linux内核之tasklet使用](https://blog.csdn.net/u010299133/article/details/100177713)  
+

doc/v4l2.md

@@ -0,0 +1,32 @@
+
+#### V4l2：
+[V4L2框架概述](https://blog.csdn.net/u013904227/article/details/80718831)  
+
+[Linux - 使用V4L2（总结）](https://blog.csdn.net/weixin_43707799/article/details/107821189)  
+[Linux V4L2之camera](https://www.cnblogs.com/vedic/p/10763838.html)  
+[深入学习Linux摄像头（二）v4l2驱动框架](https://blog.csdn.net/weixin_42462202/article/details/99680969) 
+[v4l2系列](https://blog.csdn.net/cqxcool66/category_11276218.html)
+[V4L2驱动框架详解-非常有用 v4l2.pdf](https://blog.csdn.net/weixin_42203498/article/details/126753239)  
+[V4L2控制接口](https://blog.csdn.net/zzsxyl/article/details/124478369)
+
+
+编译v4l-utils
+
+```shell
+git clone https://github.com/karbirz/v4l-utils
+# 在Makefile.am中找到contrib并删除
+./bootstrap.sh
+
+./configure --host=aarch64-linux-gnu --disable-libdvbv5 --without-libudev --disable-qv4l2 --disable-dyn-libv4l --disable-qvidcap
+
+make
+```
+
+编译yavta
+```shell
+git clone https://github.com/kabirz/yavta
+cd yavta
+aarch64-linux-gnu-gcc yavta.c -o yavta
+```
+
+