Fix USB serial number on K64 & K66

teensy3/kinetis.h

 #define HAS_KINETIS_LLWU_16CH
 #define HAS_KINETIS_ADC0
 #define HAS_KINETIS_TSI
+#define HAS_KINETIS_FLASH_FTFL
 
-// Teensy 3.1
+
+// Teensy 3.1 & 3.2
 #elif defined(__MK20DX256__)
 enum IRQ_NUMBER_t {
 	IRQ_DMA_CH0 =		0,
 #define HAS_KINETIS_ADC0
 #define HAS_KINETIS_ADC1
 #define HAS_KINETIS_TSI
+#define HAS_KINETIS_FLASH_FTFL
 
 // Teensy-LC
 #elif defined(__MKL26Z64__)
 #define HAS_KINETIS_LLWU_16CH
 #define HAS_KINETIS_ADC0
 #define HAS_KINETIS_TSI_LITE
+#define HAS_KINETIS_FLASH_FTFA
 
 
 #elif defined(__MK64FX512__)
 #define HAS_KINETIS_MPU
 #define HAS_KINETIS_ADC0
 #define HAS_KINETIS_ADC1
+#define HAS_KINETIS_FLASH_FTFE
 
 
 #elif defined(__MK66FX1M0__)
 #define HAS_KINETIS_ADC0
 #define HAS_KINETIS_ADC1
 #define HAS_KINETIS_TSI_LITE
+#define HAS_KINETIS_FLASH_FTFE
 
 
 

teensy3/usb_desc.c

 	uint32_t i, num;
 
 	__disable_irq();
+#if defined(HAS_KINETIS_FLASH_FTFA) || defined(HAS_KINETIS_FLASH_FTFL)
 	FTFL_FSTAT = FTFL_FSTAT_RDCOLERR | FTFL_FSTAT_ACCERR | FTFL_FSTAT_FPVIOL;
 	FTFL_FCCOB0 = 0x41;
 	FTFL_FCCOB1 = 15;
 	FTFL_FSTAT = FTFL_FSTAT_CCIF;
 	while (!(FTFL_FSTAT & FTFL_FSTAT_CCIF)) ; // wait
 	num = *(uint32_t *)&FTFL_FCCOB7;
+#elif defined(HAS_KINETIS_FLASH_FTFE)
+	// TODO: does not work in HSRUN mode
+	FTFL_FSTAT = FTFL_FSTAT_RDCOLERR | FTFL_FSTAT_ACCERR | FTFL_FSTAT_FPVIOL;
+	*(uint32_t *)&FTFL_FCCOB3 = 0x41070000;
+	FTFL_FSTAT = FTFL_FSTAT_CCIF;
+	while (!(FTFL_FSTAT & FTFL_FSTAT_CCIF)) ; // wait
+	num = *(uint32_t *)&FTFL_FCCOBB;
+#endif
 	__enable_irq();
 	// add extra zero to work around OS-X CDC-ACM driver bug
 	if (num < 10000000) num = num * 10;