AXI GPIO Interrupt

Hi Sebastian,

Do you know which FPGA to Processor (F2P) interrupt you are using?

If you know that you are only using one interrupt then it likely got assigned to F2P_INT0 which according to xparameters_ps.h in a Standalone BSP is defined as interrupt 61:

#define XPS_FPGA0_INT_IDtt61

So I think the interrupt math works out to what you have in the DTS okay 61 - 32 = 29 so I don't think the problem is in the DTS.

Can you post more of your code which shows what device you are opening and how you are mmap-ing?

Regards,

-Kevin

Hi Kevin,
thanks for your reply.
I understood that i use interrupt 29 (DTS). With the offset 32, i use 61 at petalinux.

#include <stdio.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

int main()
{
tint uio0_fd;
tint irq_count;
tif ((uio0_fd = open("/dev/uio0", O_RDONLY|O_SYNC)) < 0) {
tperror("open uio0");
t}

t// wait for interrupt
tif (read(uio0_fd, &irq_count, 4) != 4) {
tperror("read uio0");
t}

tprintf ("test!!!");

    return 0;
}

I understand this correctly that i wait for an interrupt with read()? If the interrupt occurs, the application continue. I have no ISR like a bare metal application.

Regards,
Sebastian

Hi,
sry i posted the wrong code.

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/mman.h>

#define GPIO_MAP_SIZE 0x10000

int main()
{
tint uio0_fd;
tint irq_count;
tvoid *ptr;


tif ((uio0_fd = open("/dev/uio0", O_RDONLY|O_SYNC)) < 0)
t{
ttperror("open uio0");
t}

tptr = mmap(NULL, GPIO_MAP_SIZE, PROT_READ, MAP_SHARED, uio0_fd, 0);


t// wait for interrupt
tif (read(uio0_fd, &irq_count, 4) != 4) {
ttperror("read uio0");
t}


tprintf ("test!!!");
tmunmap(ptr, GPIO_MAP_SIZE);

treturn 0;
}

regards,
Sebastian

Hi Sebastian,

It seems like what you are doing from code makes sense so perhaps there is another reason why the interrupt does not cause read() to unblock?

I came across this Xilinx forum thread:

http://forums.xilinx.com/t5/Embedded-Linux/UIO-interrupt-with-PS-GPIO/td-p/603502

Have you looked through the code that John Linn attached in his reply to that thread already?

Regards,

-Kevin

Hi Kevin,

thank you for your answer. Interrupts works now but i have a problem with printf() in a while loop. In the function wait_for_interrupt() is a breakpoint. If i push a button, read() unblocks the programm and wait at the breakpoint but printf() doesn't work. If i try this without a while loop, it works. With a for loop, i can push a button i times and after that, the printf() output follows i times. DO you have an idea for that?

regards,
Sebastian


For each other, here is my hardware, the device tree and the code for a axi gpio interrupt.
It's important to load your drivers at the kernel manual with the shell command:
modprobe uio_pdrv_genirq.of_id="generic-uio"
Furthermore it's important to configure and enable the interrupts at your code. After an interrupt, the interrupts have to reenable.

Hardware:
http://up.picr.de/22058574ln.jpg

Devicetree:
chosen {
        bootargs = "console=ttyPS0,115200 earlyprintk uio_pdrv_genirq.of_id=generic-uio";
     };
};

&axi_gpio_0 {
t compatible = "generic-uio";
t reg = <0x41200000 0x10000>;
tinterrupt-parent = <&intc>;
tinterrupts = <0 29 4>;
};

Code:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>

#define GPIO_MAP_SIZE tt0x10000
#define GPIO_DATA_OFFSETt0x00
#define GPIO_TRI_OFFSETtt0x04
#define GPIO_DATA2_OFFSETt0x08
#define GPIO_TRI2_OFFSETt0x0C
#define GPIO_GLOBAL_IRQtt0x11C
#define GPIO_IRQ_CONTROLt0x128
#define GPIO_IRQ_STATUStt0x120


inline void gpio_write(void *gpio_base, unsigned int offset, unsigned int value)
{
t*((volatile unsigned *)(gpio_base + offset)) = value;
}

inline unsigned int gpio_read(void *gpio_base, unsigned int offset)
{
treturn *((volatile unsigned *)(gpio_base + offset));
}

unsigned int get_memory_size(char *sysfs_path_file)
{
tFILE *size_fp;
tunsigned int size;

t// open the file that describes the memory range size that is based on the
t// reg property of the node in the device tree

tsize_fp = fopen(sysfs_path_file, "r");

tif (!size_fp) {
ttprintf("unable to open the uio size file
");
ttexit(-1);
t}

t// get the size which is an ASCII string such as 0xXXXXXXXX and then be stop
t// using the file

tfscanf(size_fp, "0x%08X", &size);
tfclose(size_fp);

treturn size;
}

void wait_for_interrupt(int fd, void *gpio_ptr)
{
tint pending = 0;
tint reenable = 1;
tunsigned int reg;

t// block on the file waiting for an interrupt */
tread(fd, (void *)&pending, sizeof(int));
t////Breakoint/////
tprintf("Interrupt!");

t// the interrupt occurred for the 1st GPIO channel so clear it
treg = gpio_read(gpio_ptr, GPIO_IRQ_STATUS);
tif (reg)
ttgpio_write(gpio_ptr, GPIO_IRQ_STATUS, 1); //


t// re-enable the interrupt in the interrupt controller thru the
t// the UIO subsystem now that it's been handled

twrite(fd, (void *)&reenable, sizeof(int));

}

int main()
{
tint uio0_fd;
tvoid *ptr;
tint gpio_size;
tint reenable = 1;


tif ((uio0_fd = open("/dev/uio0", O_RDWR)) < 0)
t{
ttperror("open uio0");
t}
telse{printf("uio0 opened
");}

tgpio_size = get_memory_size("/sys/class/uio/uio0/maps/map0/size");

tptr = mmap(NULL, gpio_size, PROT_READ|PROT_WRITE, MAP_SHARED, uio0_fd, 0);

tif (ptr == MAP_FAILED) {
tttprintf("Mmap call failure.
");
tttreturn -1;
tt}
tgpio_write(ptr, GPIO_TRI_OFFSET, 0xFF); // GPIO Channel 1 input

tgpio_write(ptr, GPIO_GLOBAL_IRQ, 0x80000000); // GIER, 31. Bit
tgpio_write(ptr, GPIO_IRQ_CONTROL, 1);  // Channel 1 Interrupt enable

twrite(uio0_fd, (void *)&reenable, sizeof(int)); // 2nd start

t//wait for interrupt
twhile(1)
t{
ttwait_for_interrupt(uio0_fd, ptr);
t}


tmunmap(ptr, gpio_size);

treturn 0;
}

Hi,
i tried to fix that. If i play with the buttons some minutes, all printf() outputs came together.
In addition, if i push a button, 1 interrupt occurs and when i releasse the button an 2. interrupt occurs.

regards,
Sebastian

Hi Sebastian,

Hmmm, I don't have an explanation as to why all of the outputs are running together.

I do have an idea about pressing and releasing an button generating an interrupt.  Since they are electro-mechanical switches on MicroZed IO Carrier board, there is a contact which has some springy-ness to it.  As a result, you will get some bounce effect upon the contact which could trigger multiple interrupts since the logic level would vary slightly as the contact bounced after being pressed/depressed.  You could look this up, it is sometimes debounced in software using polling or some other technique.

Since you have the programmable logic at your disposal, you could implement debounce logic in your hardware design.  There is an example in our older "Introduction to Zynq" SpeedWay training which includes some debounce logic in verilog but you might have an idea on how to do this yourself.

http://microzed.org/support/trainings-and-videos

Regards,

-Kevin

Hi Kevin,

I solved the problem with printf(). If puts() is used, it works.

I checked the buttons for bouncing with a oscilloscope. Thats not the problem. I print a counter for interrupts in the terminal. The same effect as "cat /proc/interrupt".
I modified my DTS in

interrupts = <0 29 1>; //rising edge
1 interrupt for rising edge, 1 interrupt for falling edge
"cat /pproc/..."=1 and my "counter"=1

interrupts = <0 29 4>; // high level
2 interrupts for rising edge, 2 interrupts for falling edge
"cat /pproc/..."=4 and my "counter"=2

regards,
Sebastian

interrupts = <0 29 1>; //rising edge
1 interrupt for rising edge, 1 interrupt for falling edge
"cat /pproc/..."=2 and my "counter"=2