Before investing a lot of time into refactoring your code, I recommend just adding some GPIO test code to the `sysfs_write` of the kernel module I posted earlier, and then kicking it off from terminal with `sudo sh -c "echo 1 > /sys/kernel/my_critical_proc/initiate"`.Are there any example pieces of code which do this which I can look at? Simple ones which just show how this is done, rather than trying to understand this from looking at big pieces of kernel code that do loads of other stuff too. Thanks
If you want to create a C program to initiate the kernel module, then something like this should work:
Code:
#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <fcntl.h>int main() { int fd; char write_byte = '1'; char read_byte; while (1) { // Open the file with read/write permissions fd = open("/sys/kernel/my_critical_proc/initiate", O_RDWR); if (fd == -1) { perror("open"); exit(1); } // Write the value to the file if (write(fd, &write_byte, sizeof(write_byte)) == -1) { perror("write"); exit(1); } // Sleep for 1 second to wait for the kernel module to finish processing sleep(1); // Read one byte from the file if (read(fd, &read_byte, 1) == -1) { perror("read"); exit(1); } // Print the read byte (optional) printf("Read byte: %c\n", read_byte); // Close the file close(fd); } return 0;}Think of the kernel module as a function that you call by writing to the/sys/kernel/my_critical_proc/initiate file, and get the return value of by reading from that file.
When writing to the file, anything you write will be passed via the `syfs_write`'s `const char *buf, size_t count` parameters. Inside the `sysfs_write` function, use the typical features of C to read whatever it was the calling program wrote via `buf` and do your dynamic processing using that.
If you need to read data back from the kernel module, write data to a `static` variable in `sysfs_write`, and then in the `sysfs_read` function, copy that variable to the `char *buf` as demonstrated with the `sprintf` function in the kernel module example.
Statistics: Posted by JinShil — Sun Jan 28, 2024 8:20 am