J722SXH01EVM: How to modify GPIO attributes in user space application?

Hi Keerthy,

It seems like that the included gpio-utils library can be used with the kernel interrupt. Tested with the included gpio-hammer example.

Tested on SK-TDA4VM example:

#include <stdio.h>
#include <fcntl.h>
#include <linux/gpio.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include "gpio-utils.h"

#define GPIO_CHIP "gpiochip0"
#define GPIO_LINE_NUMBER 52

int main() {
/*
    int fd, ret;
    unsigned int lines[1] = {GPIO_LINE_NUMBER};
	struct gpio_v2_line_request req;
    struct gpio_v2_line_values values;

    fd = open(GPIO_CHIP, O_RDWR);
    if (fd < 0) 
    {
        perror("Failed to open GPIO chip");
        return -1;
    }
    printf("Debug: fd after open(): %d\n",fd);

    memset(&req, 0, sizeof(req));

    req.offsets[0] = GPIO_LINE_NUMBER;
    req.config.flags = GPIO_V2_LINE_FLAG_OUTPUT;
    strcpy(req.consumer, "gpio_test");
    req.num_lines = 1;

    ret = ioctl(fd, GPIO_V2_GET_LINE_IOCTL, &req);
    if (ret < 0)
        perror("Failed to request GPIO line");
    
    printf("Debug: fd after get_line: %d\n", fd);
    printf("Debug: Offsets: %d\n", req.offsets[0]);

    memset(&values, 0, sizeof(values));
    values.mask = 0;
    values.bits = 0;

    printf("Debug: Mask: %llu\n", values.mask);
    printf("Debug: Bits: %llu\n", values.bits);

    ret = ioctl(fd, GPIO_V2_LINE_SET_VALUES_IOCTL, &values);
    if (ret < 0)
        perror("Failed to set GPIO line low");

    sleep(1);

    values.bits |= _BITULL(0);
    printf("Debug: Bits: %llu\n", values.bits);

    ret = ioctl(fd, GPIO_V2_LINE_SET_VALUES_IOCTL, &values);
    if (ret < 0)
        perror("Failed to set GPIO line high");
*/
/* Using gpio-utils */
    struct gpio_v2_line_values values;
    struct gpio_v2_line_config config;
    unsigned int lines[1] = {GPIO_LINE_NUMBER};
    int fd;
    int ret;
    memset(&config, 0, sizeof(config));

    //config.flags = GPIO_V2_LINE_FLAG_INPUT | GPIO_V2_LINE_FLAG_EDGE_RISING;
    config.flags = GPIO_V2_LINE_FLAG_OUTPUT;

	ret = gpiotools_request_line(GPIO_CHIP, lines, 1,
				     &config, "gpio-test");
	if (ret < 0)
		perror("Unable to request GPIO line");
	else
		fd = ret;

	values.mask = 0;
	values.bits = 0;
	gpiotools_set_bit(&values.mask, 0);
	ret = gpiotools_get_values(fd, &values);
	if (ret < 0)
        perror("Unable to get GPIO line values");

    gpiotools_set_bit(&values.bits, 0);
    gpiotools_set_values(fd, &values);
    if (ret < 0)
        perror("Unable to set GPIO line high");
}

Terminal:

# Open WKUP_GPIO0_52 from userspace and toggle high
root@tda4vm-sk:/# ./gpio_test 
[   21.678862] test_irq: irq 275, val=0
# check direction
root@tda4vm-sk:/# devmem2 0x42110038
/dev/mem opened.
Memory mapped at address 0xffff83fb7000.
Read at address  0x42110038 (0xffff83fb7038): 0xFFEFFFFF
# check rising edge trigger
root@tda4vm-sk:/# devmem2 0x4211004C
/dev/mem opened.
Memory mapped at address 0xffffafc4c000.
Read at address  0x4211004C (0xffffafc4c04c): 0x00100000
# check GPIO0_52 state
root@tda4vm-sk:/# devmem2 0x4211003C
/dev/mem opened.
Memory mapped at address 0xffffa1b96000.
Read at address  0x4211003C (0xffffa1b9603c): 0x00100000

Is there any issue with opening and configuring a GPIO line from userspace as such, and using a kernel interrupt?

Thank you,

Jin