Eric Lee / smarc-uboot

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drivers/twserial/soft_tws.c 1.74 KB
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572e6179a   Detlev Zundel   drivers/twserial:... 
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  /*
   * (C) Copyright 2009
   * Detlev Zundel, DENX Software Engineering, dzu@denx.de.
   *
1a4596601   Wolfgang Denk   Add GPL-2.0+ SPDX... 
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   * SPDX-License-Identifier:	GPL-2.0+
572e6179a   Detlev Zundel   drivers/twserial:... 
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   */
  
  #define TWS_IMPLEMENTATION
  #include <common.h>
  
  /*=====================================================================*/
  /*                         Public Functions                            */
  /*=====================================================================*/
  
  /*-----------------------------------------------------------------------
   * Read bits
   */
  int tws_read(uchar *buffer, int len)
  {
  	int rem = len;
  	uchar accu, shift;
  
  	debug("tws_read: buffer %p len %d
  ", buffer, len);
  
  	/* Configure the data pin for input */
  	tws_data_config_output(0);
  
  	/* Disable WR, i.e. setup a read */
  	tws_wr(0);
  	udelay(1);
  
  	/* Rise CE */
  	tws_ce(1);
  	udelay(1);
  
  	for (; rem > 0; ) {
  		for (shift = 0, accu = 0;
  		     (rem > 0) && (shift < 8);
  		     rem--, shift++) {
  			tws_clk(1);
  			udelay(10);
  			accu |= (tws_data_read() << shift); /* LSB first */
  			tws_clk(0);
  			udelay(10);
  		}
  		*buffer++ = accu;
  	}
  
  	/* Lower CE */
  	tws_ce(0);
  
  	return len - rem;
  }
  
  
  /*-----------------------------------------------------------------------
   * Write bits
   */
  int tws_write(uchar *buffer, int len)
  {
  	int rem = len;
  	uchar accu, shift;
  
  	debug("tws_write: buffer %p len %d
  ", buffer, len);
  
  	/* Configure the data pin for output */
  	tws_data_config_output(1);
  
  	/* Enable WR, i.e. setup a write */
  	tws_wr(1);
  	udelay(1);
  
  	/* Rise CE */
  	tws_ce(1);
  	udelay(1);
  
  	for (; rem > 0; ) {
  		for (shift = 0, accu = *buffer++;
  		     (rem > 0) && (shift < 8);
  		     rem--, shift++) {
  			tws_data(accu & 0x01); /* LSB first */
  			tws_clk(1);
  			udelay(10);
  			tws_clk(0);
  			udelay(10);
  			accu >>= 1;
  		}
  	}
  
  	/* Lower CE */
  	tws_ce(0);
  
  	return len - rem;
  }