MCUXpresso: Update usticker driver

Move clock frequency to a target specific function

Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>

targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC/us_ticker.c

@@ -29,13 +29,17 @@ const ticker_info_t* us_ticker_get_info()
 
 static bool us_ticker_inited = false;
 
+extern uint32_t us_ticker_get_clock();
+
 /** Initialize the high frequency ticker
  *
  */
 void us_ticker_init(void) {
     ctimer_config_t config;
 
-    uint32_t pclk = CLOCK_GetFreq(kCLOCK_BusClk);
+
+    uint32_t pclk = us_ticker_get_clock();
+
     uint32_t prescale = pclk / 1000000; // default to 1MHz (1 us ticks)
 
     /* Let the timer to count if re-init. */

targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC54114/TARGET_LPCXpresso/mbed_overrides.c

@@ -51,3 +51,8 @@ void rtc_setup_oscillator(void)
     SYSCON->RTCOSCCTRL |= SYSCON_RTCOSCCTRL_EN_MASK;
 }
 
+uint32_t us_ticker_get_clock()
+{
+    return CLOCK_GetFreq(kCLOCK_BusClk);;
+}
+

targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_MCU_LPC546XX/TARGET_FF_LPC546XX/mbed_overrides.c

@@ -66,6 +66,11 @@ void rtc_setup_oscillator(void)
     SYSCON->RTCOSCCTRL |= SYSCON_RTCOSCCTRL_EN_MASK;
 }
 
+uint32_t us_ticker_get_clock()
+{
+    return CLOCK_GetFreq(kCLOCK_BusClk);;
+}
+
 void ADC_ClockPower_Configuration(void)
 {
     /* SYSCON power. */

targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_MCU_LPC546XX/TARGET_LPCXpresso/mbed_overrides.c

@@ -82,6 +82,11 @@ void rtc_setup_oscillator(void)
     SYSCON->RTCOSCCTRL |= SYSCON_RTCOSCCTRL_EN_MASK;
 }
 
+uint32_t us_ticker_get_clock()
+{
+    return CLOCK_GetFreq(kCLOCK_BusClk);;
+}
+
 // Provide ethernet devices with a semi-unique MAC address from the UUID
 void mbed_mac_address(char *mac)
 {