Merge pull request #35 from facchinm/selectable_port

Dynamically switch SPI port in use

SerialFlash.h

 class SerialFlashChip
 {
 public:
+	static bool begin(SPIClass& device, uint8_t pin = 6);
 	static bool begin(uint8_t pin = 6);
 	static uint32_t capacity(const uint8_t *id);
 	static uint32_t blockSize();

SerialFlashChip.cpp

 #define CSRELEASE() DIRECT_WRITE_HIGH(cspin_basereg, cspin_bitmask)
 #define SPICONFIG   SPISettings(50000000, MSBFIRST, SPI_MODE0)
 
-#if defined(__arc__)
-// Use SPI1 on Arduino 101 (accesses chip already on the board)
-#define SPIPORT SPI1
-#elif 0
-// Add cases here, if you wish to use other SPI ports...
-#else
-// Otherwise, use the normal SPI port.
-#define SPIPORT SPI
-#endif
-
 uint16_t SerialFlashChip::dirindex = 0;
 uint8_t SerialFlashChip::flags = 0;
 uint8_t SerialFlashChip::busy = 0;
 static volatile IO_REG_TYPE *cspin_basereg;
 static IO_REG_TYPE cspin_bitmask;
 
+static SPIClass& SPIPORT = SPI;
+
 #define FLAG_32BIT_ADDR		0x01	// larger than 16 MByte address
 #define FLAG_STATUS_CMD70	0x02	// requires special busy flag check
 #define FLAG_DIFF_SUSPEND	0x04	// uses 2 different suspend commands
 //#define FLAG_DIFF_SUSPEND	0x04	// uses 2 different suspend commands
 //#define FLAG_256K_BLOCKS	0x10	// has 256K erase blocks
 
+bool SerialFlashChip::begin(SPIClass& device, uint8_t pin)
+{
+	SPIPORT = device;
+	return begin(pin);
+}
+
 bool SerialFlashChip::begin(uint8_t pin)
 {
 	uint8_t id[5];