feat(PeriphDrivers): Add MAX32657 clock measurement function (#1308)

Libraries/PeriphDrivers/Include/MAX32657/mxc_sys.h

@@ -26,6 +26,7 @@
 
 #include "mxc_device.h"
 #include "gcr_regs.h"
+#include "fcr_regs.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -115,6 +116,13 @@ typedef enum {
     MXC_SYS_CLOCK_DIV_128 = MXC_S_GCR_CLKCTRL_SYSCLK_DIV_DIV128
 } mxc_sys_system_clock_div_t;
 
+/** @brief Compare clock enumeration. Used in MXC_SYS_ClockMeasure function. */
+typedef enum {
+    MXC_SYS_COMPARE_CLOCK_RTC = MXC_S_FCR_FRQCNTCTRL_CMP_CLKSEL_RTC,
+    MXC_SYS_COMPARE_CLOCK_EXT_GPIO = MXC_S_FCR_FRQCNTCTRL_CMP_CLKSEL_EXT_GPIO,
+    MXC_SYS_COMPARE_CLOCK_INRO = MXC_S_FCR_FRQCNTCTRL_CMP_CLKSEL_INRO
+} mxc_sys_compare_clock_t;
+
 #define MXC_SYS_USN_CHECKSUM_LEN 16 // Length of the USN + padding for checksum compute
 #define MXC_SYS_USN_CSUM_FIELD_LEN 2 // Size of the checksum field in the USN
 #define MXC_SYS_USN_LEN 13 // Size of the USN including the checksum
@@ -348,6 +356,18 @@ uint32_t MXC_SYS_RiscVClockRate(void);
  */
 int MXC_SYS_LockDAP_Permanent(void);
 
+/**
+ * @brief Measure the clock frequency.
+ * 
+ * @details Assumes that measurement clock and ERFO are enabled. 
+ * Increasing compareClockTicks will provide a more accurate measurement, 
+ * but there are limits that could cause overflow.
+ * 
+ * @param clock Enumeration for which clock to measure.
+ * @param compareClockTicks Number of ticks of the comparison clock to use for measurement.
+ */
+uint32_t MXC_SYS_ClockMeasure(mxc_sys_compare_clock_t clock, uint32_t compareClockTicks);
+
 #ifdef __cplusplus
 }
 #endif

Libraries/PeriphDrivers/Source/SYS/sys_me30.c

@@ -543,4 +543,36 @@ int MXC_SYS_LockDAP_Permanent(void)
 }
 #endif
 
+/* ************************************************************************** */
+uint32_t MXC_SYS_ClockMeasure(mxc_sys_compare_clock_t clock, uint32_t compareClockTicks)
+{
+    /* Assuming that both clocks are already enabled */
+
+    /* Setup the comparison clock */
+    MXC_FCR->frqcntctrl = (MXC_FCR->frqcntctrl & ~(MXC_F_FCR_FRQCNTCTRL_CMP_CLKSEL)) | clock;
+
+    /* Set ticks of the comparison clock */
+    MXC_FCR->frqcntcmp = compareClockTicks;
+
+    /*
+     * Enable interrupt, note that we don't see the flag if we leave
+     * this disabled.
+     */
+    MXC_FCR->inten |= MXC_F_FCR_INTFL_FRQCNT;
+
+    /* Clear the interrupt flag */
+    MXC_FCR->intfl = MXC_F_FCR_INTFL_FRQCNT;
+
+    /* Start the procedure */
+    MXC_FCR->frqcntctrl |= MXC_F_FCR_FRQCNTCTRL_START;
+
+    /* Wait for the procedure to finish */
+    while (!(MXC_FCR->intfl & MXC_F_FCR_INTFL_FRQCNT)) {}
+
+    /* Calculate the frequency */
+    uint64_t freq = (uint64_t)ERFO_FREQ * (uint64_t)MXC_FCR->cmpclk / (uint64_t)MXC_FCR->refclk;
+
+    return (uint32_t)freq;
+}
+
 /**@} end of mxc_sys */