/*
   * (C) Copyright 2001
   * Erik Theisen,  Wave 7 Optics, etheisen@mindspring.com.
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  /*
   * Dallas Semiconductor's DS1621/1631 Digital Thermometer and Thermostat.
   */
  
  #include <common.h>
  #include <i2c.h>
  #include <dtt.h>
  
  /*
   * Device code
   */
  #define DTT_I2C_DEV_CODE 	0x48	/* Dallas Semi's DS1621 */
  #define DTT_READ_TEMP		0xAA
  #define DTT_READ_COUNTER	0xA8
  #define DTT_READ_SLOPE		0xA9
  #define DTT_WRITE_START_CONV	0xEE
  #define DTT_WRITE_STOP_CONV	0x22
  #define DTT_TEMP_HIGH		0xA1
  #define DTT_TEMP_LOW		0xA2
  #define DTT_CONFIG		0xAC
  
  /*
   * Config register bits
   */
  #define DTT_CONFIG_1SHOT	0x01
  #define DTT_CONFIG_POLARITY	0x02
  #define DTT_CONFIG_R0		0x04	/* ds1631 only */
  #define DTT_CONFIG_R1		0x08	/* ds1631 only */
  #define DTT_CONFIG_NVB		0x10
  #define DTT_CONFIG_TLF		0x20
  #define DTT_CONFIG_THF		0x40
  #define DTT_CONFIG_DONE		0x80
  
  
  int dtt_read(int sensor, int reg)
  {
  	int dlen;
  	uchar data[2];
  
  	/* Calculate sensor address and command */
  	sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/
  
  	/* Prepare to handle 2 byte result */
  	switch(reg) {
  	case DTT_READ_TEMP:
  	case DTT_TEMP_HIGH:
  	case DTT_TEMP_LOW:
  		dlen = 2;
  		break;
  	default:
  		dlen = 1;
  	}
  
  	/* Now try to read the register */
  	if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  		return 1;
  
  	/* Handle 2 byte result */
  	if (dlen == 2)
  		return (short)((data[0] << 8) | data[1]);
  
  	return (int)data[0];
  }
  
  
  int dtt_write(int sensor, int reg, int val)
  {
  	int dlen;
  	uchar data[2];
  
  	/* Calculate sensor address and register */
  	sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  
  	/* Handle various data sizes. */
  	switch(reg) {
  	case DTT_READ_TEMP:
  	case DTT_TEMP_HIGH:
  	case DTT_TEMP_LOW:
  		dlen = 2;
  		data[0] = (char)((val >> 8) & 0xff);	/* MSB first */
  		data[1] = (char)(val & 0xff);
  		break;
  	case DTT_WRITE_START_CONV:
  	case DTT_WRITE_STOP_CONV:
  		dlen = 0;
  		data[0] = (char)0;
  		data[1] = (char)0;
  		break;
  	default:
  		dlen = 1;
  		data[0] = (char)(val & 0xff);
  	}
  
  	/* Write value to device */
  	if (i2c_write(sensor, reg, 1, data, dlen) != 0)
  		return 1;
  
  	/* Poll NV memory busy bit in case write was to register stored in EEPROM */
  	while(i2c_reg_read(sensor, DTT_CONFIG) & DTT_CONFIG_NVB)
  		;
  
  	return 0;
  }
  
  
  int dtt_init_one(int sensor)
  {
  	int val;
  
  	/* Setup High Temp */
  	val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
  	if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0)
  		return 1;
  
  	/* Setup Low Temp - hysteresis */
  	val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
  	if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
  		return 1;
  
  	/*
  	 * Setup configuraton register
  	 *
  	 * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
  	 *
  	 * We run in polled mode, since there isn't any way to know if this
  	 * lousy device is ready to provide temperature readings on power up.
  	 */
  	val = 0x9;
  	if (dtt_write(sensor, DTT_CONFIG, val) != 0)
  		return 1;
  
  	return 0;
  }
  
  int dtt_get_temp(int sensor)
  {
  	int i;
  
  	/* Start a conversion, may take up to 1 second. */
  	dtt_write(sensor, DTT_WRITE_START_CONV, 0);
  	for (i = 0; i <= 10; i++) {
  		udelay(100000);
  		if (dtt_read(sensor, DTT_CONFIG) & DTT_CONFIG_DONE)
  			break;
  	}
  
  	return (dtt_read(sensor, DTT_READ_TEMP) / 256);
  }