Linux Device Driver >> Assembly (ARM)
workqueue
參考資訊:
1. ldd
在延遲中斷處理機制上,workqueue是另一個可以使用的方式,workqueue是執行在低優先級別上,因此,可以讓Context Switch繼續執行,意味著使用者可以在workqueue裡面呼叫sleep()相關的函式,這也是跟softirq、tasklet最大的差別,因此,workqueue是相當適合應用在耗時處理的場合
使用步驟:
1. __alloc_workqueue_key()
2. queue_work_on()
3. destroy_workqueue()
ldd.S
.global init_module .global cleanup_module .equ BUTTON, 27 .equ IRQF_TRIGGER_RISING, 1 .section .modinfo, "ae" __UNIQUE_ID_0: .asciz "license=GPL" __UNIQUE_ID_1: .asciz "author=Steward Fu" __UNIQUE_ID_2: .asciz "description=Linux Driver" .equ work_struct.data, 0 .equ work_struct.entry, 4 .equ work_struct.entry.next, 4 .equ work_struct.entry.prev, 8 .equ work_struct.func, 12 .struct 0 work_struct_s: i0: .struct . + 4 i1: .struct . + 8 i2: .struct . + 4 work_struct_e: work_struct_l = work_struct_e - work_struct_s .section .data btn_irq: .dcb 4 irq_name: .asciz "gpio_irq" work_name: .asciz "myworkqueue" work_msg: .asciz "workqueue_handler\n" mywork: .space work_struct_l myworkqueue: .dcb 4 .align 2 .section .text workqueue_handler: push {lr} ldr r0, =work_msg bl printk pop {pc} irq_handler: push {lr} mov r0, #2 ldr r1, =myworkqueue ldr r1, [r1] ldr r2, =mywork bl queue_work_on mov r0, #1 pop {pc} init_module: push {r4, r5, lr} ldr r0, =work_name mov r1, #0 mov r2, #0 mov r3, #0 mov r4, #0 push {r4} bl __alloc_workqueue_key pop {r4} ldr r1, =myworkqueue str r0, [r1] ldr r0, =mywork add r0, #work_struct.data ldr r1, =#0xffffffe0 str r1, [r0] ldr r0, =mywork add r0, #work_struct.entry @next mov r1, r0 str r1, [r0] add r0, #work_struct.entry @prev str r1, [r0] ldr r0, =mywork add r0, #work_struct.func ldr r1, =workqueue_handler str r1, [r0] mov r0, #BUTTON bl gpio_to_desc bl gpiod_to_irq ldr r1, =btn_irq str r0, [r1] ldr r1, =irq_handler mov r2, #0 mov r3, #IRQF_TRIGGER_RISING ldr r4, =irq_name mov r5, #0 push {r4, r5} bl request_threaded_irq pop {r4, r5} mov r0, #0 pop {r4, r5, pc} cleanup_module: push {lr} ldr r0, =btn_irq ldr r0, [r0] mov r1, #0 bl free_irq ldr r0, =myworkqueue ldr r0, [r0] bl destroy_workqueue pop {pc} .end
init_module: 設定GPIO中斷以及workqueue延遲處理副程式
irq_handler: 安排一個workqueue延遲處理
workqueue_handler: 列印字串
cleanup_module: 釋放中斷資源以及刪除workqueue
完成
# workqueue_handler