Imbus/kernelmod_demo
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GPIO code

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Imbus 2025-05-10 09:30:07 +02:00
parent cd15ea0d55
commit edc26eca45
1 changed files with 52 additions and 5 deletions
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57
demo_module.c
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@ -1,6 +1,11 @@
#include <linux/module.h> #include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
/*
* Last compiled with Linux 6.14.5-300.fc42.x86_64
*/
/* Meta Info */ /* Meta Info */
MODULE_DESCRIPTION("Demo kernel module."); MODULE_DESCRIPTION("Demo kernel module.");
@ -8,19 +13,61 @@ MODULE_VERSION("0.0.1");
MODULE_AUTHOR("Imbus"); MODULE_AUTHOR("Imbus");
MODULE_LICENSE("GPL"); MODULE_LICENSE("GPL");
/*
* Hard coded for RPI3
* Usually retrieved via device tree
*/
#define IO_LED 21
#define IO_BUTTON 20
#define IO_OFFSET 0
static struct gpio_desc *led, *button;
/** /**
* @brief Called on load * @brief Called on load
*/ */
static int __init demo_mod_init(void) { static int __init demo_mod_init(void) {
printk(KERN_INFO "Demo module loaded successfully..."); printk(KERN_INFO "Demo module loaded successfully...");
return 0;
int status;
led = gpio_to_desc(IO_LED + IO_OFFSET);
if (!led) {
printk("gpioctrl - Error getting pin 21\n");
return -ENODEV;
}
button = gpio_to_desc(IO_BUTTON + IO_OFFSET);
if (!button) {
printk("gpioctrl - Error getting pin 20\n");
return -ENODEV;
}
status = gpiod_direction_output(led, 0);
if (status) {
printk("gpioctrl - Error setting pin 20 to output\n");
return status;
}
status = gpiod_direction_input(button);
if (status) {
printk("gpioctrl - Error setting pin 21 to input\n");
return status;
}
gpiod_set_value(led, 1);
printk("gpioctrl - Button is %spressed\n",
gpiod_get_value(button) ? " " : "not ");
return 0;
} }
/** /**
* @brief Called on unload * @brief Called on unload
*/ */
static void __exit demo_mod_exit(void) { static void __exit demo_mod_exit(void) {
printk(KERN_INFO "Demo module unloaded successfully..."); printk(KERN_INFO "Demo module unloaded successfully...");
} }
module_init(demo_mod_init); module_init(demo_mod_init);