From 372b4822122caae394d6e5060c669352b6193b91 Mon Sep 17 00:00:00 2001
From: Florian RICHER <florian.richer@protonmail.com>
Date: Mon, 24 Feb 2025 20:42:34 +0100
Subject: [PATCH] Ajout d'un driver pour la gestion d'une led via un PIN GPIO
---
09_gpio_led_rpi3/Makefile | 7 ++
09_gpio_led_rpi3/test_module.c | 141 +++++++++++++++++++++++++++++++++
2 files changed, 148 insertions(+)
create mode 100644 09_gpio_led_rpi3/Makefile
create mode 100644 09_gpio_led_rpi3/test_module.c
diff --git a/09_gpio_led_rpi3/Makefile b/09_gpio_led_rpi3/Makefile
new file mode 100644
index 0000000..b909b3c
--- /dev/null
+++ b/09_gpio_led_rpi3/Makefile
@@ -0,0 +1,7 @@
+obj-m += test_module.o
+
+all:
+ make -C $(LINUX_MODULES_FOLDER)/build M=$(PWD) modules
+
+clean:
+ make -C $(LINUX_MODULES_FOLDER)/build M=$(PWD) clean
diff --git a/09_gpio_led_rpi3/test_module.c b/09_gpio_led_rpi3/test_module.c
new file mode 100644
index 0000000..1043699
--- /dev/null
+++ b/09_gpio_led_rpi3/test_module.c
@@ -0,0 +1,141 @@
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+
+// gpiochip0: GPIOs 512-565, parent: platform/3f200000.gpio, pinctrl-bcm2835
+// From /sys/kernel/debug/gpio
+#define RPI3_BCM2835_GPIO_OFFSET 512
+#define BCM_TO_LINUX_GPIO(bcm) (RPI3_BCM2835_GPIO_OFFSET + (bcm))
+
+static int gpio_pin = -1;
+module_param(gpio_pin, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+MODULE_PARM_DESC(gpio_pin, "BCM GPIO pin number (e.g., 17)");
+
+struct gpio_led_rpi3 {
+ int linux_gpio;
+ int bcm_gpio;
+ struct gpio_desc *desc;
+ struct led_classdev *led;
+};
+
+static struct gpio_led_rpi3 pin;
+
+static void gpio_led_rpi3_brightness_set(struct led_classdev *led_cdev, enum led_brightness brightness) {
+ pr_info("gpio_led_rpi3: Luminosité défini sur la LED %s à %d\n", led_cdev->name, brightness);
+
+ if (brightness < 0 || brightness > 1) {
+ pr_err("gpio_led_rpi3: Valeur incorrecte");
+ return;
+ }
+
+ // Applique la nouvelle valeur à la LED
+ gpiod_set_value(pin.desc, brightness);
+ pr_info("gpio_pin_rpi3: GPIO %d (BCM %d) défini à %d\n", pin.linux_gpio, pin.bcm_gpio, brightness);
+}
+
+static enum led_brightness gpio_led_rpi3_brightness_get(struct led_classdev *led_cdev) {
+ pr_info("Luminosité lu sur la LED %s, valeur actuelle: %d\n", led_cdev->name, led_cdev->brightness);
+ return led_cdev->brightness;
+}
+
+static int register_rpi3_gpio_pin(void)
+{
+ if (gpio_pin < 0) {
+ pr_err("gpio_led_rpi3: You must specify 'gpio_pin' (e.g., gpio_pin=17)\n");
+ return -EINVAL;
+ }
+
+ pin.bcm_gpio = gpio_pin;
+ pin.linux_gpio = BCM_TO_LINUX_GPIO(pin.bcm_gpio);
+
+ // Récupération du descripteur GPIO à partir du numéro Globale Linux
+ pin.desc = gpio_to_desc(pin.linux_gpio);
+ if (!pin.desc) {
+ pr_err("gpio_led_rpi3: Le GPIO %d (BCM %d) non trouvé\n", pin.linux_gpio, pin.bcm_gpio);
+ return -ENODEV;
+ }
+
+ // Réclame le PIN GPIO
+ if (gpiod_direction_output(pin.desc, 0)) {
+ pr_err("gpio_led_rpi3: Impossible de configurer le GPIO %d\n", pin.linux_gpio);
+ gpiod_put(pin.desc);
+ return -EINVAL;
+ }
+
+ // Réinitialise la LED
+ gpiod_set_value(pin.desc, 0);
+
+ return 0;
+}
+
+static void unregister_rpi3_gpio_pin(void)
+{
+ // Turn LED off and release GPIO
+ gpiod_set_value(pin.desc, 0);
+ gpiod_put(pin.desc);
+ pr_info("gpio_led_rpi3: GPIO %d (BCM %d) libéré (LED OFF)\n", pin.linux_gpio, pin.bcm_gpio);
+}
+
+static int register_rpi3_led(void)
+{
+ pin.led = kzalloc(sizeof(struct led_classdev), GFP_KERNEL);
+ if (!pin.led) {
+ pr_err("Échec de l'allocation de mémoire pour la LED virtuelle\n");
+ return -ENOMEM;
+ }
+
+ pin.led->name = kasprintf(GFP_KERNEL, "rpi3-led:white:gpio-%d", pin.bcm_gpio);
+ pin.led->color = LED_COLOR_ID_WHITE;
+ pin.led->brightness = 0;
+ pin.led->max_brightness = 1;
+ pin.led->brightness_set = gpio_led_rpi3_brightness_set;
+ pin.led->brightness_get = gpio_led_rpi3_brightness_get;
+
+ int ret = led_classdev_register(NULL, pin.led);
+ if (ret < 0) {
+ kfree(pin.led->name);
+ kfree(pin.led);
+ pr_err("Impossible d'ajouter la LED virtuelle\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static void unregister_rpi3_led(void)
+{
+ led_classdev_unregister(pin.led);
+ kfree(pin.led->name);
+ kfree(pin.led);
+}
+
+static int __init gpio_led_rpi3_init(void)
+{
+ int ret = register_rpi3_gpio_pin();
+ if (ret != 0) {
+ return ret;
+ }
+
+ ret = register_rpi3_led();
+ if (ret != 0) {
+ unregister_rpi3_gpio_pin();
+ return ret;
+ }
+
+ return 0;
+}
+
+static void __exit gpio_led_rpi3_exit(void)
+{
+ unregister_rpi3_led();
+ unregister_rpi3_gpio_pin();
+}
+
+module_init(gpio_led_rpi3_init);
+module_exit(gpio_led_rpi3_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Florian RICHER <florian.richer@protonmail.com>");
+MODULE_DESCRIPTION("Un module noyau pour utiliser un PIN GPIO d'une RPI en tant que LED");
+MODULE_VERSION("1.0");
\ No newline at end of file