确定设备树中使用的虚拟中断号

在imx6ull的芯片用户手册中，的第三章中断中。有一些保留的寄存器可以用来触发GIC SPI中断。

如何触发中断

可以使用devmem2命令在直接写GIC的PENDING寄存器

这个是在GIC手册里写的，并不在imx6ull的手册里

GICD_ISPENDRn有多个寄存器，每个寄存器中每一位对应一个GIC中断，写入1就可以触发中断



我们在设备树中使用的中断号是122，那么加上32。 122+32 = 154就是GIC的中断号，每一个GIC有32位，可以表示32个中断。

那么154/32 = 4…26，所以用到第5个寄存器中的，第26位。

GIC在上面的基地址是0x200，那么第5个寄存器偏移地址为0x200+(4*4)+Distribution地址（0x00a01000） = 0x00a01210

对应devmem2的写入基地址，然后第26位置1。写入的值就是0x4000000

实验步骤记录

显示内核日志：


echo "7 4 1 7" > /proc/sys/kernel/printk


root@npi:~/100ask# insmod virtual_int_controller.ko
[   67.405164] virtual_intc_init 138
[   67.405669] virtual_intc_probe irq_to_parent = 74
[   67.405880] virtual_intc_probe irq_base = 237

这里提示向上的中断是74号，这是chained_intc对应的虚拟中断号

这里由于使用了legacy的分配方式，4个子中断号会一起分配出来。一开始的中断号是237。

# 查看注册的中断号
root@npi:/sys/kernel/irq/78# cd /sys/kernel/irq/74
root@npi:/sys/kernel/irq/74# ls
actions  chip_name  hwirq  name  per_cpu_count  type  wakeup
root@npi:/sys/kernel/irq/74# cat chip_name 
GIC-0
root@npi:/sys/kernel/irq/74# cat hwirq 
154
root@npi:/sys/kernel/irq/74# cd ../237
root@npi:/sys/kernel/irq/237# ls
actions  chip_name  hwirq  name  per_cpu_count  type  wakeup
root@npi:/sys/kernel/irq/237# cat hwirq 
0
root@npi:/sys/kernel/irq/237# cat chip_name 
100ask_virtual_intc
root@npi:/sys/kernel/irq/237# cd ../238/
root@npi:/sys/kernel/irq/238# cat hwirq 
1
root@npi:/sys/kernel/irq/238# cat chip_name 
100ask_virtual_intc
root@npi:/sys/kernel/irq/238# cat ../239/hwirq 
2
root@npi:/sys/kernel/irq/238# cat ../239/chip_name 
100ask_virtual_intc
root@npi:/sys/kernel/irq/238# cat ../240/hwirq 
3
root@npi:/sys/kernel/irq/238# cat ../240/chip_name 
100ask_virtual_intc

# 装载gpio驱动程序
root@npi:~/100ask# insmod gpio_key_drv.ko 
[  521.062571] /home/chen/Documents/mygit/100ask_rk3288_module/16_interrupt/01_virtua
l_interrupt/gpio_key_drv.c gpio_key_init line 97
[  521.085613] /home/chen/Documents/mygit/100ask_rk3288_module/16_interrupt/01_virtua
l_interrupt/gpio_key_drv.c gpio_key_probe line 53
[  521.100161] virtual_intc_irq_unmask 55
[  521.105632] devm_request_irq 237 for 100ask_virtual_key0, err = 0
[  521.114816] virtual_intc_irq_unmask 55
[  521.120082] devm_request_irq 238 for 100ask_virtual_key1, err = 0
[  521.126262] virtual_intc_irq_unmask 55
[  521.132005] devm_request_irq 239 for 100ask_virtual_key2, err = 0
[  521.138387] virtual_intc_irq_unmask 55
[  521.142207] devm_request_irq 240 for 100ask_virtual_key3, err = 0
# 这里申请的就是237~240，和上面的中断号对应

root@npi:~/100ask# cat /proc/interrupts 
#.....注册了4个中断函数
237:          0  100ask_virtual_intc   0 Edge      100ask_virtual_key0
238:          0  100ask_virtual_intc   1 Edge      100ask_virtual_key1
239:          0  100ask_virtual_intc   2 Edge      100ask_virtual_key2
240:          0  100ask_virtual_intc   3 Edge      100ask_virtual_key3
#.....

可以使用devmem2来触发imx6ull的中断：

root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  251.270794] virtual_intc_irq_ack 40
[  251.275143] key 100ask_virtual_key0 0

Memory mapped at address 0x76f92000.
Value at address 0xA01210 (0x76f92210): 0x0
Written 0x4000000; readback 0x4000000
root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  361.006812] virtual_intc_irq_ack 40
[  361.011162] key 100ask_virtual_key1 0

Memory mapped at address 0x76f43000.
Value at address 0xA01210 (0x76f43210): 0x0
Written 0x4000000; readback 0x4000000
root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  363.896727] virtual_intc_irq_ack 40
[  363.901077] key 100ask_virtual_key0 1

Memory mapped at address 0x76f9f000.
Value at address 0xA01210 (0x76f9f210): 0x0
Written 0x4000000; readback 0x4000000
root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  364.766890] virtual_intc_irq_ack 40
[  364.770937] key 100ask_virtual_key1 1

Memory mapped at address 0x76f72000.
Value at address 0xA01210 (0x76f72210): 0x0
Written 0x4000000; readback 0x4000000
root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  365.466905] virtual_intc_irq_ack 40
[  365.471245] key 100ask_virtual_key0 2

Memory mapped at address 0x76f78000.
Value at address 0xA01210 (0x76f78210): 0x0
Written 0x4000000; readback 0x4000000
root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  366.096701] virtual_intc_irq_ack 40
[  366.101046] key 100ask_virtual_key1 2

Memory mapped at address 0x76f1b000.
Value at address 0xA01210 (0x76f1b210): 0x0
Written 0x4000000; readback 0x4000000
root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  366.736501] virtual_intc_irq_ack 40
[  366.740830] key 100ask_virtual_key2 0

Memory mapped at address 0x76f24000.
Value at address 0xA01210 (0x76f24210): 0x0
Written 0x4000000; readback 0x4000000

如果修改virtual_intc_controller.c的触发函数为电平触发

//irq_set_chip_and_handler(virq, &virtual_intc_irq_chip, handle_edge_irq);  
    irq_set_chip_and_handler(virq, &virtual_intc_irq_chip, handle_level_irq);

结果就有mask和unmask函数了

root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  320.670037] virtual_intc_irq_mask_ack 50
[  320.674982] key 100ask_virtual_key2 0
[  320.678693] virtual_intc_irq_unmask 55

Memory mapped at address 0x76fd6000.
Value at address 0xA01210 (0x76fd6210): 0x0
Written 0x4000000; readback 0x4000000
root@npi:~/100ask# devmem2 0x00a01210 w 0x4000000
/dev/mem opened.[  414.802182] virtual_intc_irq_mask_ack 50
[  414.806964] key 100ask_virtual_key1 0
[  414.810675] virtual_intc_irq_unmask 55

Memory mapped at address 0x76ff7000.
Value at address 0xA01210 (0x76ff7210): 0x0
Written 0x4000000; readback 0x4000000