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Application to register interrupt and write simple interrupt service routine
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Detect user input from push button / DIP switch:
modprobe gpio_interrupt gpio_number=<n>
When user presses the button or flips the dip switch, a message will be printed
to kernel console.
1. If the user connects to the console on board using serial connection,
the message "Interrupt happened at gpio:<gpio_number>" will be printed on the
console.
2. If the user connects to the console on board using ssh, the message can be
viewed from kernel log via "dmesg" command.
Note: User will need to do "rmmod gpio_interrupt" prior in order to change
gpio_number by calling "modprobe gpio_interrupt gpio_number=<n>" again
User will need to get the GPIO number from /sys/class/gpio/ by using
command 'ls'. E.g.
root@socfpga~:# ls /sys/class/gpio/
gpiochip150 gpiochip152 gpiochip156 gpiochip160
gpiochip192 gpiochip224
From the listing, n can be obtained. The GPIO number may vary for different
design with different device tree entries; this is due to the GPIO numbers are
auto-assign by the kernel.
To confirm the n is associated to which peripheral, user needs to match the
label of the GPIO chip to the address of push button and DIP switch in device
tree.
e.g.
root@socfpga~:# cat /sys/class/gpio/gpiochip150/label
/sopc@0/bridge@0xc0000000/gpio@0x1000100C0
In this reference design, DIP switch is at address 0x10080 while the push button
is at address 0x100c0. So in this case GPIO number 150 - 151 are allocated to
push button 0 - 1.
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