periph_clk_gating: add reference counter

components/driver/include/driver/periph_ctrl.h

@@ -28,6 +28,10 @@ extern "C" {
  *
  * Clock for the module will be ungated, and reset de-asserted.
  *
+ * @note If periph_module_enable is called a number of times,
+ *       periph_module_disable has to be called the same number of times
+ *       in order to put the peripheral into disabled state.
+ *
  * @return     NULL
  *
  */
@@ -40,6 +44,10 @@ void periph_module_enable(periph_module_t periph);
  *
  * Clock for the module will be gated, reset asserted.
  *
+ * @note If periph_module_enable is called a number of times,
+ *       periph_module_disable has to be called the same number of times
+ *       in order to put the peripheral into disabled state.
+ *
  * @return     NULL
  *
  */

components/driver/periph_ctrl.c

@@ -17,22 +17,33 @@
 
 static portMUX_TYPE periph_spinlock = portMUX_INITIALIZER_UNLOCKED;
 
+static uint8_t ref_counts[PERIPH_MODULE_MAX] = {0};
+
 void periph_module_enable(periph_module_t periph)
 {
+    assert(periph < PERIPH_MODULE_MAX);
     portENTER_CRITICAL_SAFE(&periph_spinlock);
-    periph_ll_enable_clk_clear_rst(periph);
+    if (ref_counts[periph] == 0) {
+        periph_ll_enable_clk_clear_rst(periph);
+    }
+    ref_counts[periph]++;
     portEXIT_CRITICAL_SAFE(&periph_spinlock);
 }
 
 void periph_module_disable(periph_module_t periph)
 {
+    assert(periph < PERIPH_MODULE_MAX);
     portENTER_CRITICAL_SAFE(&periph_spinlock);
-    periph_ll_disable_clk_set_rst(periph);
+    ref_counts[periph]--;
+    if (ref_counts[periph] == 0) {
+        periph_ll_disable_clk_set_rst(periph);
+    }
     portEXIT_CRITICAL_SAFE(&periph_spinlock);
 }
 
 void periph_module_reset(periph_module_t periph)
 {
+    assert(periph < PERIPH_MODULE_MAX);
     portENTER_CRITICAL_SAFE(&periph_spinlock);
     periph_ll_reset(periph);
     portEXIT_CRITICAL_SAFE(&periph_spinlock);

components/soc/soc/esp32/include/soc/periph_defs.h

@@ -55,6 +55,7 @@ typedef enum {
     PERIPH_AES_MODULE,
     PERIPH_SHA_MODULE,
     PERIPH_RSA_MODULE,
+    PERIPH_MODULE_MAX
 } periph_module_t;
 
 #ifdef __cplusplus

components/soc/soc/esp32s2/include/soc/periph_defs.h

@@ -54,6 +54,7 @@ typedef enum {
     PERIPH_CRYPTO_DMA_MODULE,        //this DMA is shared between AES and SHA
     PERIPH_AES_DMA_MODULE,
     PERIPH_SHA_DMA_MODULE,
+    PERIPH_MODULE_MAX
 } periph_module_t;
 
 typedef enum {