add 08_Interrupt/11

STM32MP157/doc_pic/08_Interrupt/11_异常向量表的安装与调用.md

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+## 异常向量表的安装与调用
+
+### 1. 回顾中断的发生、处理过程
+
+* 中断发生的硬件过程
+
+![image-20210626114958795](pic/08_Interrupt/060_interrupt_flow.png)
+
+
+
+* 中断处理的软件处理流程
+  * CPU执行完当前指令，检查到发生了中断，跳到向量表
+  * 保存现场、执行GIC提供的处理函数、恢复现场
+
+
+
+### 2. 异常向量表的安装
+
+#### 2.1 复制向量表
+
+* 汇编代码
+
+```c
+// arch\arm\kernel\head.S
+1. bl	__lookup_processor_type
+   ...... 
+2. bl	__create_page_tables
+3. ldr	r13, =__mmap_switched
+4. b	__enable_mmu
+   b	__turn_mmu_on
+   mov	r3, r13
+   ret	r3
+5. __mmap_switched: // arch\arm\kernel\head-common.S
+6. b	start_kernel
+```
+
+
+
+* 复制向量表
+
+```c
+start_kernel // init\main.c
+    setup_arch(&command_line); // arch\arm\kernel\setup.c
+		paging_init(mdesc);    // arch\arm\mm\mmu.c
+			devicemaps_init(mdesc); // arch\arm\mm\mmu.c
+				vectors = early_alloc(PAGE_SIZE * 2); // 1.分配新向量表
+				early_trap_init(vectors);             // 2.从代码把向量表复制到新向量表
+
+				// 3. 映射新向量表到虚拟地址0xffff0000
+                /*
+                 * Create a mapping for the machine vectors at the high-vectors
+                 * location (0xffff0000).  If we aren't using high-vectors, also
+                 * create a mapping at the low-vectors virtual address.
+                 */
+                map.pfn = __phys_to_pfn(virt_to_phys(vectors));
+                map.virtual = 0xffff0000;
+                map.length = PAGE_SIZE;
+            #ifdef CONFIG_KUSER_HELPERS
+                map.type = MT_HIGH_VECTORS;
+            #else
+                map.type = MT_LOW_VECTORS;
+            #endif
+                create_mapping(&map);
+```
+
+![image-20210626120817244](pic/08_Interrupt/061_copy_vectors.png)
+
+#### 2.2 向量表在哪
+
+上面代码中可以看到代码中向量表位于`__vectors_start`，它在`arch/arm/kernel/vmlinux.lds`中定义：
+
+```shell
+ __vectors_start = .;
+ .vectors 0xffff0000 : AT(__vectors_start) {
+  *(.vectors)
+ }
+ . = __vectors_start + SIZEOF(.vectors);
+ __vectors_end = .;
+ __stubs_start = .;
+ .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) {
+  *(.stubs)
+ }
+```
+
+在代码里搜`.vectors`，可以找到向量表：
+
+![image-20210626124004537](pic/08_Interrupt/062_vectors_in_source.png)
+
+### 3. 中断向量
+
+发生中断时，CPU跳到向量表去执行`b vector_irq`。
+
+vector_irq函数使用宏来定义：
+
+![image-20210626125245059](pic/08_Interrupt/063_vector_irq.png)
+
+
+
+### 4. 处理流程
+
+![image-20210626130003359](pic/08_Interrupt/064_handle_irq.png)
+
+
+
+### 5. 处理函数
+
+![image-20210626130412855](pic/08_Interrupt/065_irq_handler.png)

STM32MP157/doc_pic/08_Interrupt/12_GIC驱动程序分析.md

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+## GIC驱动程序分析
+
+参考资料：
+
+* [linux kernel的中断子系统之（七）：GIC代码分析](http://www.wowotech.net/irq_subsystem/gic_driver.html)
+
+### 1. 回顾
+
+
+
+### 2. 函数调用过程
+
+```c
+start_kernel (init\main.c)
+    init_IRQ (arch\arm\kernel\irq.c)
+    	irqchip_init (drivers\irqchip\irqchip.c)
+    		of_irq_init (drivers\of\irq.c)
+    			desc->irq_init_cb = match->data;
+
+                ret = desc->irq_init_cb(desc->dev,
+                            desc->interrupt_parent);
+
+```
+
+#### 2.1 platform_driver支持多个device
+
+按照设备树的套路：驱动程序注册platform_driver，它的of_match_table里有多个of_device_id，表示能支持多个设备。
+
+有多种版本的GIC，在内核为每一类GIC定义一个结构体of_device_id，并放在一个段里：
+
+```c
+// drivers\irqchip\irq-gic.c
+IRQCHIP_DECLARE(gic_400, "arm,gic-400", gic_of_init);
+IRQCHIP_DECLARE(arm11mp_gic, "arm,arm11mp-gic", gic_of_init);
+IRQCHIP_DECLARE(arm1176jzf_dc_gic, "arm,arm1176jzf-devchip-gic", gic_of_init);
+IRQCHIP_DECLARE(cortex_a15_gic, "arm,cortex-a15-gic", gic_of_init);
+IRQCHIP_DECLARE(cortex_a9_gic, "arm,cortex-a9-gic", gic_of_init);
+IRQCHIP_DECLARE(cortex_a7_gic, "arm,cortex-a7-gic", gic_of_init);
+IRQCHIP_DECLARE(msm_8660_qgic, "qcom,msm-8660-qgic", gic_of_init);
+IRQCHIP_DECLARE(msm_qgic2, "qcom,msm-qgic2", gic_of_init);
+IRQCHIP_DECLARE(pl390, "arm,pl390", gic_of_init);
+```
+
+把宏`IRQCHIP_DECLARE`展开：
+
+```c
+// include\linux\irqchip.h
+#define IRQCHIP_DECLARE(name, compat, fn) OF_DECLARE_2(irqchip, name, compat, fn)
+
+#define OF_DECLARE_2(table, name, compat, fn) \
+		_OF_DECLARE(table, name, compat, fn, of_init_fn_2)
+
+#define _OF_DECLARE(table, name, compat, fn, fn_type)			\
+	static const struct of_device_id __of_table_##name		\
+		__used __section(__##table##_of_table)			\
+		 = { .compatible = compat,				\
+		     .data = (fn == (fn_type)NULL) ? fn : fn  }
+```
+
+展开示例：
+
+```c
+IRQCHIP_DECLARE(cortex_a7_gic, "arm,cortex-a7-gic", gic_of_init);
+展开后得到：
+static const struct of_device_id __of_table_cortex_a7_gic		\
+	__used __section(__irqchip_of_table)			\
+	 = { .compatible = "arm,cortex-a7-gic",				\
+		 .data = gic_of_init  }
+```
+
+
+
+#### 2.2 没有定义platform_driver但是套路一样
+
+`drivers\irqchip\irqchip.c`中并没有定义一个platform_driver，但是套路是一样的。
+
+![image-20210626083319383](pic/08_Interrupt/058_irqchip_init.png)
+
+调用过程：
+
+![image-20210626084850583](pic/08_Interrupt/059_gic_init.png)