54 lines
2.8 KiB
Markdown
54 lines
2.8 KiB
Markdown
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## Independent Interrupts Management
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### Introduction
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Calling `rt_hw_interrupt_disable` in multiple places on `rt-thread` may cause interruption delays when the application requires accurate interrupt responses. This is because the system cannot generate any interrupts except abnormal interrupts after disabling interrupts. This is a common problem in the interrupt management of the operating system. The independent interrupt management module is designed to solve this problem.
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The independent interrupt management module is designed to solve the problem of interrupt delays caused by calling `rt_hw_interrupt_disable` in multiple places on `rt-thread`. The module is implemented by rewrite the `rt_hw_interrupt_disable` and `rt_hw_interrupt_enable` functions in the `libcpu` library.
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### Usage
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- Add the following code to the project's `board.c` file.
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```
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#ifdef RT_USING_INDEPENDENT_INTERRUPT_MANAGEMENT
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#define RT_NVIC_PRO_BITS __NVIC_PRIO_BITS
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rt_base_t rt_hw_interrupt_disable(void)
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{
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rt_base_t level = __get_BASEPRI();
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__set_BASEPRI(RT_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - RT_NVIC_PRO_BITS));
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__ISB();
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__DSB();
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return level;
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}
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void rt_hw_interrupt_enable(rt_base_t level)
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{
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__set_BASEPRI(level);
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}
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#endif /* RT_USING_INDEPENDENT_INTERRUPT_MANAGEMENT */
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```
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- Add the following configuration to the `Kconfig` file in the `board` directory.
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```
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menuconfig RT_USING_INDEPENDENT_INTERRUPT_MANAGEMENT
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bool "Enable independent interrupt management"
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default n
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if RT_USING_INDEPENDENT_INTERRUPT_MANAGEMENT
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config RT_MAX_SYSCALL_INTERRUPT_PRIORITY
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int "Set max syscall interrupt priority"
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range 0 7
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default 2
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endif
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```
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- Select `RT_USING_INDEPENDENT_INTERRUPT_MANAGEMENT` to enable this feature.
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- Select `RT_MAX_SYSCALL_INTERRUPT_PRIORITY` to set the maximum priority of the interrupt that can be called by the system call. The default value is 2.
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### Description
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- The [basepri](https://developer.arm.com/documentation/107706/0100/Exceptions-and-interrupts-overview/Special-registers-for-exception-masking/BASEPRI) register is used in the functions to complete the interrupt management.
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- For example, if `RT_MAX_SYSCALL_INTERRUPT_PRIORITY` is set to 0x01, the system masking only interrupts with a priority of `0x01-0xFF`.
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- Interrupts with a priority of 0 are not managed by the system and can continue to respond to interrupts after `rt_hw_interrupt_disable` is called.
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- When using the [basepri](https://developer.arm.com/documentation/107706/0100/Exceptions-and-interrupts-overview/Special-registers-for-exception-masking/BASEPRI) register for independent interrupt management, note that interrupts with a priority value lower than `RT_MAX_SYSCALL_INTERRUPT_PRIORITY` cannot call any `system API`.
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