feat(epicardium): Add hardware/peripheral-lock module

Signed-off-by: Rahix <rahix@rahix.de>

epicardium/modules/hardware.c

@@ -150,6 +150,11 @@ int hardware_early_init(void)
 	 */
 	stream_init();
 
+	/*
+	 * Hardware/Peripheral Locks
+	 */
+	hwlock_init();
+
 	return 0;
 }
 

epicardium/modules/hw-lock.c

+#include "modules/log.h"
+#include "modules/modules.h"
+
+#include "FreeRTOS.h"
+#include "task.h"
+#include "semphr.h"
+
+#include <errno.h>
+
+static StaticSemaphore_t hwlock_mutex_data[_HWLOCK_MAX];
+static SemaphoreHandle_t hwlock_mutex[_HWLOCK_MAX];
+/* Which task is holding the lock */
+static TaskHandle_t hwlock_tasks[_HWLOCK_MAX];
+
+void hwlock_init(void)
+{
+	for (int i = 0; i < _HWLOCK_MAX; i++) {
+		hwlock_mutex[i] =
+			xSemaphoreCreateMutexStatic(&hwlock_mutex_data[i]);
+	}
+}
+
+int hwlock_acquire(enum hwlock_periph p, TickType_t wait)
+{
+	if (p >= _HWLOCK_MAX) {
+		return -EINVAL;
+	}
+
+	if (xSemaphoreTake(hwlock_mutex[p], wait) != pdTRUE) {
+		LOG_WARN("hwlock", "Lock %u is busy.", p);
+		return -EBUSY;
+	}
+
+	hwlock_tasks[p] = xTaskGetCurrentTaskHandle();
+
+	return 0;
+}
+
+int hwlock_release(enum hwlock_periph p)
+{
+	int ret = 0;
+
+	if (p >= _HWLOCK_MAX) {
+		return -EINVAL;
+	}
+
+	if (hwlock_tasks[p] != xTaskGetCurrentTaskHandle()) {
+		LOG_ERR("hwlock",
+			"Lock %u is released by task \"%s\" while it was acquired by \"%s\"",
+			p,
+			pcTaskGetName(NULL),
+			pcTaskGetName(hwlock_tasks[p]));
+		ret = -EACCES;
+	}
+
+	if (xSemaphoreGive(hwlock_mutex[p]) != pdTRUE) {
+		LOG_ERR("hwlock", "Lock %u not released correctly.", p);
+		ret = -EINVAL;
+	}
+
+	return ret;
+}

epicardium/modules/meson.build

@@ -5,6 +5,7 @@ module_sources = files(
   'fileops.c',
   'gpio.c',
   'hardware.c',
+  'hw-lock.c',
   'leds.c',
   'lifecycle.c',
   'light_sensor.c',

epicardium/modules/modules.h

@@ -37,6 +37,17 @@ void vBleTask(void *pvParameters);
 bool ble_shall_start(void);
 void ble_uart_write(uint8_t *pValue, uint8_t len);
 
+/* ---------- Hardware (Peripheral) Locks ---------------------------------- */
+void hwlock_init(void);
+
+enum hwlock_periph {
+	HWLOCK_I2C = 0,
+	_HWLOCK_MAX,
+};
+
+int hwlock_acquire(enum hwlock_periph p, TickType_t wait);
+int hwlock_release(enum hwlock_periph p);
+
 /* ---------- Display ------------------------------------------------------ */
 /* Forces an unlock of the display. Only to be used in Epicardium */
 void disp_forcelock();

epicardium/modules/pmic.c

@@ -45,7 +45,13 @@ void vPmicTask(void *pvParameters)
 			MAX77650_setSFT_RST(0x2);
 		}
 
+		while (hwlock_acquire(HWLOCK_I2C, pdMS_TO_TICKS(500)) < 0) {
+			LOG_WARN("pmic", "Failed to acquire I2C. Retrying ...");
+			vTaskDelay(pdMS_TO_TICKS(500));
+		}
+
 		uint8_t int_flag = MAX77650_getINT_GLBL();
+		hwlock_release(HWLOCK_I2C);
 
 		if (int_flag & MAX77650_INT_nEN_F) {
 			/* Button was pressed */