/*
   * Copyright (C) 2015 PHYTEC Messtechnik GmbH
   *               2017 Freie Universität Berlin
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   *
   */
  
  /**
   * @ingroup     drivers_tcs37727
   * @{
   *
   * @file
   * @brief       Driver for the AMS TCS37727 Color Light-To-Digital Converter
   *
   * @author      Felix Siebel <f.siebel@phytec.de>
   * @author      Johann Fischer <j.fischer@phytec.de>
   * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
   *
   * @}
   */
  
  #include <string.h>
  
  #include "log.h"
  #include "assert.h"
  
  #include "tcs37727.h"
  #include "tcs37727-internal.h"
  
  #define ENABLE_DEBUG    (0)
  #include "debug.h"
  
  #define I2C_SPEED       I2C_SPEED_FAST
  #define BUS             (dev->p.i2c)
  #define ADR             (dev->p.addr)
  
  int tcs37727_init(tcs37727_t *dev, const tcs37727_params_t *params)
  {
      uint8_t tmp;
  
      /* check parameters */
      assert(dev && params);
  
      /* initialize the device descriptor */
      memcpy(&dev->p, params, sizeof(tcs37727_params_t));
  
      /* setup the I2C bus */
      i2c_acquire(BUS);
      if (i2c_init_master(BUS, I2C_SPEED) < 0) {
          i2c_release(BUS);
          LOG_ERROR("[tcs37727] init: error initializing I2C bus\n");
          return TCS37727_NOBUS;
      }
  
      /* check if we can communicate with the device */
      i2c_read_reg(BUS, ADR, TCS37727_ID, &tmp);
      if (tmp != TCS37727_ID_VALUE) {
          i2c_release(BUS);
          LOG_ERROR("[tcs37727] init: error while reading ID register\n");
          return TCS37727_NODEV;
      }
  
      /* configure gain and conversion time */
      i2c_write_reg(BUS, ADR, TCS37727_ATIME, TCS37727_ATIME_TO_REG(dev->p.atime));
      i2c_write_reg(BUS, ADR, TCS37727_CONTROL, TCS37727_CONTROL_AGAIN_4);
      dev->again = 4;
  
      /* enable the device */
      tmp = (TCS37727_ENABLE_AEN | TCS37727_ENABLE_PON);
      i2c_write_reg(BUS, ADR, TCS37727_ENABLE, tmp);
  
      i2c_release(BUS);
  
      return TCS37727_OK;
  }
  
  void tcs37727_set_rgbc_active(const tcs37727_t *dev)
  {
      uint8_t reg;
  
      assert(dev);
  
      i2c_acquire(BUS);
      i2c_read_reg(BUS, ADR, TCS37727_ENABLE, &reg);
      reg |= (TCS37727_ENABLE_AEN | TCS37727_ENABLE_PON);
      i2c_write_reg(BUS, ADR, TCS37727_ENABLE, reg);
      i2c_release(BUS);
  }
  
  void tcs37727_set_rgbc_standby(const tcs37727_t *dev)
  {
      uint8_t reg;
  
      assert(dev);
  
      i2c_acquire(BUS);
      i2c_read_reg(BUS, ADR, TCS37727_ENABLE, &reg);
      reg &= ~TCS37727_ENABLE_AEN;
      if (!(reg & TCS37727_ENABLE_PEN)) {
          reg &= ~TCS37727_ENABLE_PON;
      }
      i2c_write_reg(BUS, ADR, TCS37727_ENABLE, reg);
      i2c_release(BUS);
  }
  
  static uint8_t tcs37727_trim_gain(tcs37727_t *dev, int rawc)
  {
      uint8_t reg_again = 0;
      int val_again = dev->again;
  
      if (rawc < TCS37727_AG_THRESHOLD_LOW) {
          switch (val_again) {
              case 1:
                  reg_again = TCS37727_CONTROL_AGAIN_4;
                  val_again = 4;
                  break;
  
              case 4:
                  reg_again = TCS37727_CONTROL_AGAIN_16;
                  val_again = 16;
                  break;
  
              case 16:
                  reg_again = TCS37727_CONTROL_AGAIN_60;
                  val_again = 60;
                  break;
  
              case 60:
              default:
                  return -1;
          }
      }
      else if (rawc > TCS37727_AG_THRESHOLD_HIGH) {
          switch (val_again) {
              case 60:
                  reg_again = TCS37727_CONTROL_AGAIN_16;
                  val_again = 16;
                  break;
  
              case 16:
                  reg_again = TCS37727_CONTROL_AGAIN_4;
                  val_again = 4;
                  break;
  
              case 4:
                  reg_again = TCS37727_CONTROL_AGAIN_1;
                  val_again = 1;
                  break;
  
              case 1:
              default:
                  return -1;
          }
      }
      else {
          return 0;
      }
  
      i2c_acquire(BUS);
      uint8_t reg = 0;
      if (i2c_read_reg(BUS, ADR, TCS37727_CONTROL, &reg) != 1) {
          i2c_release(BUS);
          return -2;
      }
      reg &= ~TCS37727_CONTROL_AGAIN_MASK;
      reg |= reg_again;
      if (i2c_write_reg(BUS, ADR, TCS37727_CONTROL, reg) != 1) {
          i2c_release(BUS);
          return -2;
      }
      i2c_release(BUS);
      dev->again = val_again;
  
      return 0;
  }
  
  void tcs37727_read(const tcs37727_t *dev, tcs37727_data_t *data)
  {
      uint8_t buf[8];
  
      assert(dev && data);
  
      i2c_acquire(BUS);
      i2c_read_regs(BUS, ADR, (TCS37727_INC_TRANS | TCS37727_CDATA), buf, 8);
      i2c_release(BUS);
  
      int32_t tmpc = ((uint16_t)buf[1] << 8) | buf[0];
      int32_t tmpr = ((uint16_t)buf[3] << 8) | buf[2];
      int32_t tmpg = ((uint16_t)buf[5] << 8) | buf[4];
      int32_t tmpb = ((uint16_t)buf[7] << 8) | buf[6];
      DEBUG("rawr: %"PRIi32" rawg %"PRIi32" rawb %"PRIi32" rawc %"PRIi32"\n",
            tmpr, tmpg, tmpb, tmpc);
  
      /* Remove IR component as described in the DN40.  */
      int32_t ir = (tmpr + tmpg + tmpb - tmpc) >> 1;
      tmpr -= ir;
      tmpg -= ir;
      tmpb -= ir;
  
      /* Color temperature calculation as described in the DN40. */
      int32_t ct = (CT_COEF_IF * tmpb) / tmpr + CT_OFFSET_IF;
  
      /* Lux calculation as described in the DN40.  */
      int32_t gi = R_COEF_IF * tmpr + G_COEF_IF * tmpg + B_COEF_IF * tmpb;
      /* TODO: add Glass Attenuation Factor GA compensation */
      int32_t cpl = (dev->p.atime * dev->again) / DGF_IF;
      int32_t lux = gi / cpl;
  
      /* Autogain */
      tcs37727_trim_gain((tcs37727_t *)dev, tmpc);
  
      data->red = (tmpr < 0) ? 0 : (tmpr * 1000) / cpl;
      data->green = (tmpg < 0) ? 0 : (tmpg * 1000) / cpl;
      data->blue = (tmpb < 0) ? 0 : (tmpb * 1000) / cpl;
      data->clear = (tmpb < 0) ? 0 : (tmpc * 1000) / cpl;
      data->lux = (lux < 0) ? 0 : lux;
      data->ct = (ct < 0) ? 0 : ct;
  }