text: /* mbed Microcontroller Library
   * Copyright (c) 2006-2013 ARM Limited
   * SPDX-License-Identifier: Apache-2.0
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  #include "mbed_assert.h"
  #include "i2c_api.h"
  
  #if DEVICE_I2C
  
  #include "cmsis.h"
  #include "pinmap.h"
  
  static const PinMap PinMap_I2C_SDA[] = {
      {P0_0 , I2C_1, 3},
      {P0_10, I2C_2, 2},
      {P0_19, I2C_1, 3},
      {P0_27, I2C_0, 1},
      {NC   , NC   , 0}
  };
  
  static const PinMap PinMap_I2C_SCL[] = {
      {P0_1 , I2C_1, 3},
      {P0_11, I2C_2, 2},
      {P0_20, I2C_1, 3},
      {P0_28, I2C_0, 1},
      {NC   , NC,    0}
  };
  
  #define I2C_CONSET(x)       (x->i2c->I2CONSET)
  #define I2C_CONCLR(x)       (x->i2c->I2CONCLR)
  #define I2C_STAT(x)         (x->i2c->I2STAT)
  #define I2C_DAT(x)          (x->i2c->I2DAT)
  #define I2C_SCLL(x, val)    (x->i2c->I2SCLL = val)
  #define I2C_SCLH(x, val)    (x->i2c->I2SCLH = val)
  
  static const uint32_t I2C_addr_offset[2][4] = {
      {0x0C, 0x20, 0x24, 0x28},
      {0x30, 0x34, 0x38, 0x3C}
  };
  
  static inline void i2c_conclr(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
      I2C_CONCLR(obj) = (start << 5)
                      | (stop << 4)
                      | (interrupt << 3)
                      | (acknowledge << 2);
  }
  
  static inline void i2c_conset(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
      I2C_CONSET(obj) = (start << 5)
                      | (stop << 4)
                      | (interrupt << 3)
                      | (acknowledge << 2);
  }
  
  // Clear the Serial Interrupt (SI)
  static inline void i2c_clear_SI(i2c_t *obj) {
      i2c_conclr(obj, 0, 0, 1, 0);
  }
  
  static inline int i2c_status(i2c_t *obj) {
      return I2C_STAT(obj);
  }
  
  // Wait until the Serial Interrupt (SI) is set
  static int i2c_wait_SI(i2c_t *obj) {
      int timeout = 0;
      while (!(I2C_CONSET(obj) & (1 << 3))) {
          timeout++;
          if (timeout > 100000) return -1;
      }
      return 0;
  }
  
  static inline void i2c_interface_enable(i2c_t *obj) {
      I2C_CONSET(obj) = 0x40;
  }
  
  static inline void i2c_power_enable(i2c_t *obj) {
      switch ((int)obj->i2c) {
          case I2C_0: LPC_SC->PCONP |= 1 << 7; break;
          case I2C_1: LPC_SC->PCONP |= 1 << 19; break;
          case I2C_2: LPC_SC->PCONP |= 1 << 26; break;
      }
  }
  
  void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
      // determine the SPI to use
      I2CName i2c_sda = (I2CName)pinmap_peripheral(sda, PinMap_I2C_SDA);
      I2CName i2c_scl = (I2CName)pinmap_peripheral(scl, PinMap_I2C_SCL);
      obj->i2c = (LPC_I2C_TypeDef *)pinmap_merge(i2c_sda, i2c_scl);
      MBED_ASSERT((int)obj->i2c != NC);
      
      // enable power
      i2c_power_enable(obj);
      
      // set default frequency at 100k
      i2c_frequency(obj, 100000);
      i2c_conclr(obj, 1, 1, 1, 1);
      i2c_interface_enable(obj);
      
      pinmap_pinout(sda, PinMap_I2C_SDA);
      pinmap_pinout(scl, PinMap_I2C_SCL);
  }
  
  inline int i2c_start(i2c_t *obj) {
      int status = 0;
      int isInterrupted = I2C_CONSET(obj) & (1 << 3);
  
      // 8.1 Before master mode can be entered, I2CON must be initialised to:
      //  - I2EN STA STO SI AA - -
      //  -  1    0   0   x  x - -
      // if AA = 0, it can't enter slave mode
      i2c_conclr(obj, 1, 1, 0, 1);
  
      // The master mode may now be entered by setting the STA bit
      // this will generate a start condition when the bus becomes free
      i2c_conset(obj, 1, 0, 0, 1);
      // Clearing SI bit when it wasn't set on entry can jump past state
      // 0x10 or 0x08 and erroneously send uninitialized slave address.
      if (isInterrupted)
          i2c_clear_SI(obj);
  
      i2c_wait_SI(obj);
      status = i2c_status(obj);
  
      // Clear start bit now that it's transmitted
      i2c_conclr(obj, 1, 0, 0, 0);
      return status;
  }
  
  inline int i2c_stop(i2c_t *obj) {
      int timeout = 0;
  
      // write the stop bit
      i2c_conset(obj, 0, 1, 0, 0);
      i2c_clear_SI(obj);
      
      // wait for STO bit to reset
      while(I2C_CONSET(obj) & (1 << 4)) {
          timeout ++;
          if (timeout > 100000) return 1;
      }
  
      return 0;
  }
  
  static inline int i2c_do_write(i2c_t *obj, int value, uint8_t addr) {
      // write the data
      I2C_DAT(obj) = value;
      
      // clear SI to init a send
      i2c_clear_SI(obj);
      
      // wait and return status
      i2c_wait_SI(obj);
      return i2c_status(obj);
  }
  
  static inline int i2c_do_read(i2c_t *obj, int last) {
      // we are in state 0x40 (SLA+R tx'd) or 0x50 (data rx'd and ack)
      if(last) {
          i2c_conclr(obj, 0, 0, 0, 1); // send a NOT ACK
      } else {
          i2c_conset(obj, 0, 0, 0, 1); // send a ACK
      }
      
      // accept byte
      i2c_clear_SI(obj);
      
      // wait for it to arrive
      i2c_wait_SI(obj);
      
      // return the data
      return (I2C_DAT(obj) & 0xFF);
  }
  
  void i2c_frequency(i2c_t *obj, int hz) {
      // [TODO] set pclk to /4
      uint32_t PCLK = SystemCoreClock / 4;
      
      uint32_t pulse = PCLK / (hz * 2);
      
      // I2C Rate
      I2C_SCLL(obj, pulse);
      I2C_SCLH(obj, pulse);
  }
  
  // The I2C does a read or a write as a whole operation
  // There are two types of error conditions it can encounter
  //  1) it can not obtain the bus
  //  2) it gets error responses at part of the transmission
  //
  // We tackle them as follows:
  //  1) we retry until we get the bus. we could have a "timeout" if we can not get it
  //      which basically turns it in to a 2)
  //  2) on error, we use the standard error mechanisms to report/debug
  //
  // Therefore an I2C transaction should always complete. If it doesn't it is usually
  // because something is setup wrong (e.g. wiring), and we don't need to programatically
  // check for that
  
  int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
      int count, status;
      
      status = i2c_start(obj);
      
      if ((status != 0x10) && (status != 0x08)) {
          i2c_stop(obj);
          return I2C_ERROR_BUS_BUSY;
      }
      
      status = i2c_do_write(obj, (address | 0x01), 1);
      if (status != 0x40) {
          i2c_stop(obj);
          return I2C_ERROR_NO_SLAVE;
      }
      
      // Read in all except last byte
      for (count = 0; count < (length - 1); count++) {
          int value = i2c_do_read(obj, 0);
          status = i2c_status(obj);
          if (status != 0x50) {
              i2c_stop(obj);
              return count;
          }
          data[count] = (char) value;
      }
      
      // read in last byte
      int value = i2c_do_read(obj, 1);
      status = i2c_status(obj);
      if (status != 0x58) {
          i2c_stop(obj);
          return length - 1;
      }
      
      data[count] = (char) value;
      
      // If not repeated start, send stop.
      if (stop) {
          i2c_stop(obj);
      }
      
      return length;
  }
  
  int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
      int i, status;
      
      status = i2c_start(obj);
      
      if ((status != 0x10) && (status != 0x08)) {
          i2c_stop(obj);
          return I2C_ERROR_BUS_BUSY;
      }
      
      status = i2c_do_write(obj, (address & 0xFE), 1);
      if (status != 0x18) {
          i2c_stop(obj);
          return I2C_ERROR_NO_SLAVE;
      }
      
      for (i=0; i<length; i++) {
          status = i2c_do_write(obj, data[i], 0);
          if(status != 0x28) {
              i2c_stop(obj);
              return i;
          }
      }
      
      // clearing the serial interrupt here might cause an unintended rewrite of the last byte
      // see also issue report https://mbed.org/users/mbed_official/code/mbed/issues/1
      // i2c_clear_SI(obj);
      
      // If not repeated start, send stop.
      if (stop) {
          i2c_stop(obj);
      }
      
      return length;
  }
  
  void i2c_reset(i2c_t *obj) {
      i2c_stop(obj);
  }
  
  int i2c_byte_read(i2c_t *obj, int last) {
      return (i2c_do_read(obj, last) & 0xFF);
  }
  
  int i2c_byte_write(i2c_t *obj, int data) {
      int ack;
      int status = i2c_do_write(obj, (data & 0xFF), 0);
      
      switch(status) {
          case 0x18: case 0x28:       // Master transmit ACKs
              ack = 1;
              break;
          case 0x40:                  // Master receive address transmitted ACK
              ack = 1;
              break;
          case 0xB8:                  // Slave transmit ACK
              ack = 1;
              break;
          default:
              ack = 0;
              break;
      }
      
      return ack;
  }
  
  void i2c_slave_mode(i2c_t *obj, int enable_slave) {
      if (enable_slave != 0) {
          i2c_conclr(obj, 1, 1, 1, 0);
          i2c_conset(obj, 0, 0, 0, 1);
      } else {
          i2c_conclr(obj, 1, 1, 1, 1);
      }
  }
  
  int i2c_slave_receive(i2c_t *obj) {
      int status;
      int retval;
      
      status = i2c_status(obj);
      switch(status) {
          case 0x60: retval = 3; break;
          case 0x70: retval = 2; break;
          case 0xA8: retval = 1; break;
          default  : retval = 0; break;
      }
      
      return(retval);
  }
  
  int i2c_slave_read(i2c_t *obj, char *data, int length) {
      int count = 0;
      int status;
      
      do {
          i2c_clear_SI(obj);
          i2c_wait_SI(obj);
          status = i2c_status(obj);
          if((status == 0x80) || (status == 0x90)) {
              data[count] = I2C_DAT(obj) & 0xFF;
          }
          count++;
      } while (((status == 0x80) || (status == 0x90) ||
              (status == 0x060) || (status == 0x70)) && (count < length));
   
      // Clear old status and wait for Serial Interrupt. 
      i2c_clear_SI(obj);
      i2c_wait_SI(obj);
   
      // Obtain new status.
      status = i2c_status(obj);
   
      if(status != 0xA0) {
          i2c_stop(obj);
      }
   
      i2c_clear_SI(obj);
      
      return count;
  }
  
  int i2c_slave_write(i2c_t *obj, const char *data, int length) {
      int count = 0;
      int status;
      
      if(length <= 0) {
          return(0);
      }
      
      do {
          status = i2c_do_write(obj, data[count], 0);
          count++;
      } while ((count < length) && (status == 0xB8));
      
      if ((status != 0xC0) && (status != 0xC8)) {
          i2c_stop(obj);
      }
      
      i2c_clear_SI(obj);
      
      return(count);
  }
  
  void i2c_slave_address(i2c_t *obj, int idx, uint32_t address, uint32_t mask) {
      uint32_t addr;
      
      if ((idx >= 0) && (idx <= 3)) {
          addr = ((uint32_t)obj->i2c) + I2C_addr_offset[0][idx];
          *((uint32_t *) addr) = address & 0xFF;
          addr = ((uint32_t)obj->i2c) + I2C_addr_offset[1][idx];
          *((uint32_t *) addr) = mask & 0xFE;
      }
  }
  
  const PinMap *i2c_master_sda_pinmap()
  {
      return PinMap_I2C_SDA;
  }
  
  const PinMap *i2c_master_scl_pinmap()
  {
      return PinMap_I2C_SCL;
  }
  
  const PinMap *i2c_slave_sda_pinmap()
  {
      return PinMap_I2C_SDA;
  }
  
  const PinMap *i2c_slave_scl_pinmap()
  {
      return PinMap_I2C_SCL;
  }
  
  #endif  // #if DEVICE_I2C
  