[FL-2797] Signal Generator app (#1793)

* Signal Generator app
* MCO pin initialization in app
* furi_hal_pwm documentation

Co-authored-by: あく <alleteam@gmail.com>

firmware/targets/f7/furi_hal/furi_hal_clock.h

@@ -4,6 +4,33 @@
 extern "C" {
 #endif
 
+#include <stm32wbxx_ll_rcc.h>
+
+typedef enum {
+    FuriHalClockMcoLse,
+    FuriHalClockMcoSysclk,
+    FuriHalClockMcoMsi100k,
+    FuriHalClockMcoMsi200k,
+    FuriHalClockMcoMsi400k,
+    FuriHalClockMcoMsi800k,
+    FuriHalClockMcoMsi1m,
+    FuriHalClockMcoMsi2m,
+    FuriHalClockMcoMsi4m,
+    FuriHalClockMcoMsi8m,
+    FuriHalClockMcoMsi16m,
+    FuriHalClockMcoMsi24m,
+    FuriHalClockMcoMsi32m,
+    FuriHalClockMcoMsi48m,
+} FuriHalClockMcoSourceId;
+
+typedef enum {
+    FuriHalClockMcoDiv1 = LL_RCC_MCO1_DIV_1,
+    FuriHalClockMcoDiv2 = LL_RCC_MCO1_DIV_2,
+    FuriHalClockMcoDiv4 = LL_RCC_MCO1_DIV_4,
+    FuriHalClockMcoDiv8 = LL_RCC_MCO1_DIV_8,
+    FuriHalClockMcoDiv16 = LL_RCC_MCO1_DIV_16,
+} FuriHalClockMcoDivisorId;
+
 /** Early initialization */
 void furi_hal_clock_init_early();
 
@@ -25,6 +52,16 @@ void furi_hal_clock_suspend_tick();
 /** Continue SysTick counter operation */
 void furi_hal_clock_resume_tick();
 
+/** Enable clock output on MCO pin
+ * 
+ * @param      source  MCO clock source
+ * @param      div     MCO clock division
+*/
+void furi_hal_clock_mco_enable(FuriHalClockMcoSourceId source, FuriHalClockMcoDivisorId div);
+
+/** Disable clock output on MCO pin */
+void furi_hal_clock_mco_disable();
+
 #ifdef __cplusplus
 }
 #endif