How to use SPORT driver

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1. Introducation
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The ADSP-21535 DSP has two identical synchronous serial ports, 
or SPORTs.  These iports support a variety of serial data 
communications protocols and can provide a direct interconnection 
between processors in a multiprocessor system.

The two SPORTs can be operated by opening /dev/sport0 and/or 
/dev/sport1.

The driver supply typical character driver interface.

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2. The connection of two SPORT
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These pins must be connected:

Tx SPORT		      Rx SPORT
  TFS		<------->	RFS
  DT		<------->	DR
  TCLK		<------->	RCLK


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3. Configuration of the communication
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ioctl code				comment
CMD_SPORT_ENABLE			enable sport
CMD_SPORT_DISABLE			disable sport
CMD_SPORT_SET_TX_BAUDRATE		change TFSDIV and TSCLKDIV
CMD_SPORT_SET_RX_BAUDRATE		change RFSDIV and RSCLKDIV
CMD_SPORT_SET_WORD_LENGTH  		set serial word length	
					(3~16 bit)

SPxTCLK frequency = (SCLK frequency) / (2 x (SPORTx_TSCLDIV + 1))
SPxRCLK frequency = (SCLK frequency) / (2 x (SPORTx_RSCLDIV + 1))

SPxTFSCLK frequency = (CLKOUT frequency) / (SPORTx_TFSDIV + 1)
SPxRFSCLK frequency = (CLKOUT frequency) / (SPORTx_RFSDIV + 1)


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4. Receive data
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fd = open("/dev/sportx", O_RDONLY, 0);
...
read(fd, buffer_rx, number_of_bytes);
...
close(fd);


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5. Send data
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fd = open("/dev/sportx", O_WRONLY, 0);
...
write(fd, buffer_tx, number_of_bytes);
...
close(fd);