补充中断处理接口.
Signed-off-by: lion.chan <cy187lion@sina.com>
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@ -69,13 +69,62 @@ Err: 0
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## Linux 中断编程
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获取中断信息：
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```cpp
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/**
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* of_irq_get - Decode a node's IRQ and return it as a Linux irq number
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* @file drivers/of/irq.c
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* @dev: pointer to device tree node
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* @index: zero-based index of the irq
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*
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* Returns Linux irq number on success, or -EPROBE_DEFER if the irq domain
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* is not yet created.
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*
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*/
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int of_irq_get(struct device_node *dev, int index);
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/**
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* platform_get_irq - get an IRQ for a device
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* @file drivers/base/platform.c
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* @dev: platform device
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* @num: IRQ number index
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* @brief 包含 of_irq_get()
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*/
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int platform_get_irq(struct platform_device *dev, unsigned int num);
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```
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注册中断处理程序：
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```cpp
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/**
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* @file kernel/irq/manage.c
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* @param irq 要申请的硬件中断号。
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* @param handler 是向系统登记的中断处理函数，是一个回调函数，中断发生时，系统调用这个函数。
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* @param handler 是向系统登记的中断处理函数，是一个回调函数，中断发生时，系统调用这个函数。为 NULL 时使用默认的处理，这个相当于中断的上半段。
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* @param thread_fn 中断发生时，如果 handler 为 NULL，就直接将 thread_fn 扔到内核线程中去执行。
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* @param irqflags 是中断处理的属性
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* SA_INTERRUPT：则表示中断处理程序是快速处理程序，快速处理程序被调用时屏蔽所有中断，慢速处理程序不屏蔽；
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* SA_SHIRQ：表示多个设备共享中断
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* IRQF_SHARED - allow sharing the irq among several devices
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* IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
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* IRQF_TIMER - Flag to mark this interrupt as timer interrupt
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* IRQF_PERCPU - Interrupt is per cpu
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* IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
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* IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
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* registered first in an shared interrupt is considered for
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* performance reasons)
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* IRQF_ONESHOT - Interrupt is not reenabled after the hardirq handler finished.
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* Used by threaded interrupts which need to keep the
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* irq line disabled until the threaded handler has been run.
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* IRQF_NO_SUSPEND - Do not disable this IRQ during suspend. Does not guarantee
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* that this interrupt will wake the system from a suspended
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* state. See Documentation/power/suspend-and-interrupts.txt
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* IRQF_FORCE_RESUME - Force enable it on resume even if IRQF_NO_SUSPEND is set
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* IRQF_NO_THREAD - Interrupt cannot be threaded
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* IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device
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* resume time.
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* IRQF_COND_SUSPEND - If the IRQ is shared with a NO_SUSPEND user, execute this
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* interrupt handler after suspending interrupts. For system
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* wakeup devices users need to implement wakeup detection in
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* their interrupt handlers.
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* @param devname An ascii name for the claiming device. 使用cat /proc/interrupt 可以查看中断程序名字。
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* @param dev_id 在中断共享时会用到，一般设置为这个设备的设备结构体或者 NULL。
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* 注册共享中断时不能为NULL，因为卸载时需要这个做参数，避免卸载其它中断服务函数。
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@ -85,6 +134,10 @@ Err: 0
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* -EBUSY：表示中断已经被占用且不能共享。
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* @brief 申请 IRQ
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*/
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int request_threaded_irq(unsigned int irq, irq_handler_t handler,
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irq_handler_t thread_fn, unsigned long irqflags,
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const char *devname, void *dev_id);
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int request_irq(unsigned int irq,
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void (*handler)(int irq, void *dev_id, struct pt_regs *regs),
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unsigned long irqflags,
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@ -102,7 +155,68 @@ void free_irq(unsigned int irq, void *dev_id);
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2. 如果采用共享中断方式，所有使用 request_irq 注册的中断时 flags 都要加上 IRQF_SHARED 这个共享参数，表明其实共享中断。
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3. 对于共享中断，每一个申请共享的中断，申请和释放时都要给 request_irq 和 free_irq 的最后一个参数 dev 和 id_dev 传递一个指针，将来来中断的时候，将会传递这个指针到每个中断函数中，而中断函数就可以用来区分到底是不是它的中断，是则执行，不是则判断后直接退出中断处理函数即可。同时在 free_irq 时也会使用这个指针，查找这个贡献中断链表上了所有注册的 irq，只有在这个指针能对的上的时候，才会删除它所在的链表节点（如果是最后一个节点还要释放该中断）。所在在编写中断处理函数时该指针必须是唯一的，通常传的这个指针是该设备结构体的地址，这个每个设备不一样所以肯定是唯一的。
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下列 3 个函数用于禁能/使能一个中断源。
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对于资源管理 Linux 内核提供了一组 Devm API。Devm APIs 是一组便捷易用的接口，通过该接口申请的内核资源是跟设备（device）有关的，在设备（device）被 detached 或者驱动（driver）卸载（unloaded）时，会被自动释放。针对以上中断资源管理，有以下 Devm 版本的 API：
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```cpp
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/**
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* @file kernel/irq/devres.c
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* @param dev 设备结构体。
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* @param irq 要申请的硬件中断号。
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* @param handler 是向系统登记的中断处理函数，是一个回调函数，中断发生时，系统调用这个函数（运行于中断上下文），
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函数需要判断是否为自身中断，若是则关闭自身中断并返回 IRQ_WAKE_THREAD。
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为 NULL 时使用默认的处理。
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* @param thread_fn 中断发生时，如果 handler 为 NULL，thread_fn 将在默认 handler 执行完毕后以内核线程形式运行。
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* 否则待 handler 返回 IRQ_WAKE_THREAD 后以内核线程形式执行。
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* @param irqflags 是中断处理的属性
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* IRQF_SHARED - allow sharing the irq among several devices
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* IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
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* IRQF_TIMER - Flag to mark this interrupt as timer interrupt
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* IRQF_PERCPU - Interrupt is per cpu
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* IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
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* IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
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* registered first in an shared interrupt is considered for
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* performance reasons)
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* IRQF_ONESHOT - Interrupt is not reenabled after the hardirq handler finished.
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* Used by threaded interrupts which need to keep the
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* irq line disabled until the threaded handler has been run.
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* IRQF_NO_SUSPEND - Do not disable this IRQ during suspend. Does not guarantee
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* that this interrupt will wake the system from a suspended
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* state. See Documentation/power/suspend-and-interrupts.txt
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* IRQF_FORCE_RESUME - Force enable it on resume even if IRQF_NO_SUSPEND is set
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* IRQF_NO_THREAD - Interrupt cannot be threaded
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* IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device
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* resume time.
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* IRQF_COND_SUSPEND - If the IRQ is shared with a NO_SUSPEND user, execute this
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* interrupt handler after suspending interrupts. For system
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* wakeup devices users need to implement wakeup detection in
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* their interrupt handlers.
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* @param devname An ascii name for the claiming device. 使用cat /proc/interrupt 可以查看中断程序名字。
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* @param dev_id 在中断共享时会用到，一般设置为这个设备的设备结构体或者 NULL。
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* 注册共享中断时不能为NULL，因为卸载时需要这个做参数，避免卸载其它中断服务函数。
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* @return
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* 0：表示成功
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* -INVAL：表示中断号无效或处理函数指针为 NULL
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* -EBUSY：表示中断已经被占用且不能共享。
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* @brief 申请 IRQ
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*/
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extern int __must_check
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devm_request_threaded_irq(struct device *dev, unsigned int irq,
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irq_handler_t handler, irq_handler_t thread_fn,
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unsigned long irqflags, const char *devname,
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void *dev_id);
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static inline int __must_check
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devm_request_irq(struct device *dev, unsigned int irq, irq_handler_t handler,
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unsigned long irqflags, const char *devname, void *dev_id)
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{
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return devm_request_threaded_irq(dev, irq, handler, NULL, irqflags,
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devname, dev_id);
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}
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extern void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id);
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```
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禁能/使能中断源：
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```cpp
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// 禁能中断源
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