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RIOT/cpu/kinetis_common/periph/i2c.c 11.1 KB
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  /*
   * Copyright (C) 2014 Freie Universität Berlin
   * Copyright (C) 2014 PHYTEC Messtechnik GmbH
   * Copyright (C) 2015 Eistec AB
   *
   * 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     cpu_kinetis_common_i2c
   *
   * @note        This driver only implements the 7-bit addressing master mode.
   *
   * @{
   *
   * @file
   * @brief       Low-level I2C driver implementation
   *
   * @author      Johann Fischer <j.fischer@phytec.de>
   * @author      Joakim Nohlgård <joakim.nohlgard@eistec.se>
   *
   * @}
   */
  
  #include <stdint.h>
  
  #include "cpu.h"
  #include "irq.h"
  #include "mutex.h"
  #include "periph_conf.h"
  #include "periph/i2c.h"
  
  #define ENABLE_DEBUG    (0)
  /* Define ENABLE_TRACE to 1 to enable printing of all TX/RX bytes to UART for extra verbose debugging */
  #define ENABLE_TRACE    (0)
  #include "debug.h"
  
  #if ENABLE_TRACE
  #define TRACE(...) DEBUG(__VA_ARGS__)
  #else
  #define TRACE(...)
  #endif
  /* guard file in case no I2C device is defined */
  #if I2C_NUMOF
  
  /**
   * @brief Array holding one pre-initialized mutex for each I2C device
   */
  static mutex_t locks[] =  {
  #if I2C_0_EN
      [I2C_0] = MUTEX_INIT,
  #endif
  #if I2C_1_EN
      [I2C_1] = MUTEX_INIT,
  #endif
  #if I2C_2_EN
      [I2C_2] = MUTEX_INIT
  #endif
  #if I2C_3_EN
      [I2C_3] = MUTEX_INIT
  #endif
  };
  
  int i2c_acquire(i2c_t dev)
  {
      if ((unsigned int)dev >= I2C_NUMOF) {
          return -1;
      }
      mutex_lock(&locks[dev]);
      return 0;
  }
  
  int i2c_release(i2c_t dev)
  {
      if ((unsigned int)dev >= I2C_NUMOF) {
          return -1;
      }
      mutex_unlock(&locks[dev]);
      return 0;
  }
  
  int i2c_init_master(i2c_t dev, i2c_speed_t speed)
  {
      DEBUG("i2c_init_master: %lu, %lu\n", (unsigned long)dev, (unsigned long) speed);
      I2C_Type *i2c;
      PORT_Type *i2c_port;
      int pin_scl = 0;
      int pin_sda = 0;
      uint32_t baudrate_flags = 0;
  
      /** @todo Kinetis I2C: Add automatic baud rate flags selection function */
      /*
       * See the Chapter "I2C divider and hold values":
       *     Kinetis K60 Reference Manual, section 51.4.1.10, Table 51-41.
       *     Kinetis MKW2x  Reference Manual, section 52.4.1.10, Table 52-41.
       *
       * baud rate = I2C_module_clock / (mul × ICR)
       */
      switch (speed) {
          case I2C_SPEED_LOW:
              baudrate_flags |= I2C_F_MULT(KINETIS_I2C_F_MULT_LOW) |
                  I2C_F_ICR(KINETIS_I2C_F_ICR_LOW);
              break;
  
          case I2C_SPEED_NORMAL:
              baudrate_flags |= I2C_F_MULT(KINETIS_I2C_F_MULT_NORMAL) |
                  I2C_F_ICR(KINETIS_I2C_F_ICR_NORMAL);
              break;
  
          case I2C_SPEED_FAST:
              baudrate_flags |= I2C_F_MULT(KINETIS_I2C_F_MULT_FAST) |
                  I2C_F_ICR(KINETIS_I2C_F_ICR_FAST);
              break;
  
          case I2C_SPEED_FAST_PLUS:
              baudrate_flags |= I2C_F_MULT(KINETIS_I2C_F_MULT_FAST_PLUS) |
                  I2C_F_ICR(KINETIS_I2C_F_ICR_FAST_PLUS);
              break;
  
          default:
              /*
               * High speed mode is not supported on Kinetis devices,
               * see: https://community.freescale.com/thread/316371
               *
               * Hardware allows setting the baud rate high enough but the
               * capacitance of the bus and lacking a proper high speed mode SCL
               * driver will make the signals go out of spec.
               */
              return -2;
      }
  
      /* read static device configuration */
      switch (dev) {
  #if I2C_0_EN
  
          case I2C_0:
              i2c = I2C_0_DEV;
              i2c_port = I2C_0_PORT;
              pin_scl = I2C_0_SCL_PIN;
              pin_sda = I2C_0_SDA_PIN;
              I2C_0_CLKEN();
              I2C_0_PORT_CLKEN();
              break;
  #endif
  
          default:
              return -1;
      }
  
      /* configure pins, alternate output */
      i2c_port->PCR[pin_scl] = I2C_0_PORT_CFG;
      i2c_port->PCR[pin_sda] = I2C_0_PORT_CFG;
  
      i2c->F = baudrate_flags;
  
      /* enable i2c-module and interrupt */
      i2c->C1 = I2C_C1_IICEN_MASK | I2C_C1_IICIE_MASK | I2C_C1_TXAK_MASK;
      i2c->C2 = 0;
  
      return 0;
  }
  
  /*
   * Check for bus master arbitration lost.
   * Arbitration is lost in the following circumstances:
   * 1. SDA is sampled as low when the master drives high during an
   *    address or data transmit cycle.
   * 2. SDA is sampled as low when the master drives high during the
   *    acknowledge bit of a data receive cycle.
   * 3. A START cycle is attempted when the bus is busy.
   * 4. A repeated START cycle is requested in slave mode.
   * 5. A STOP condition is detected when the master did not request
   *    it.
   */
  static inline int _i2c_arbitration_lost(I2C_Type *dev)
  {
      return (int)(dev->S & I2C_S_ARBL_MASK);
  }
  
  static inline int _i2c_start(I2C_Type *dev, uint8_t address, uint8_t rw_flag)
  {
      /* bus free ? */
      if (dev->S & I2C_S_BUSY_MASK) {
          DEBUG("i2c:_start: bus busy\n");
          return -1;
      }
  
      dev->S = I2C_S_IICIF_MASK;
  
      dev->C1 = I2C_C1_IICEN_MASK | I2C_C1_MST_MASK | I2C_C1_TX_MASK;
      dev->D = address << 1 | (rw_flag & 1);
  
      /* wait for bus-busy to be set */
      while (!(dev->S & I2C_S_BUSY_MASK)) {
          if (_i2c_arbitration_lost(dev)) {
              DEBUG("i2c:_start: arbitration lost\n");
              return -1;
          }
      }
  
      /* wait for address transfer to complete */
      while (!(dev->S & I2C_S_IICIF_MASK));
  
      dev->S = I2C_S_IICIF_MASK;
  
      if (_i2c_arbitration_lost(dev)) {
          DEBUG("i2c:_start: arbitration lost late\n");
          return -1;
      }
  
      /* check for receive acknowledge */
      if (dev->S & I2C_S_RXAK_MASK) {
          DEBUG("i2c:_start: no addr ack\n");
          return -1;
      }
  
      return 0;
  }
  
  static inline int _i2c_restart(I2C_Type *dev, uint8_t address, uint8_t rw_flag)
  {
      /* put master in rx mode and repeat start */
      dev->C1 |= I2C_C1_RSTA_MASK;
      dev->D = address << 1 | (rw_flag & 1);
  
      /* wait for address transfer to complete */
      while (!(dev->S & I2C_S_IICIF_MASK));
  
      dev->S = I2C_S_IICIF_MASK;
  
      if (_i2c_arbitration_lost(dev)) {
          DEBUG("i2c:_restart: arbitration lost\n");
          return -1;
      }
  
      /* check for receive acknowledge */
      if (dev->S & I2C_S_RXAK_MASK) {
          DEBUG("i2c:_restart: no addr ack\n");
          return -1;
      }
  
      return 0;
  }
  
  static inline int _i2c_receive(I2C_Type *dev, uint8_t *data, int length)
  {
      int n = 0;
  
      /* set receive mode */
      dev->C1 = I2C_C1_IICEN_MASK | I2C_C1_MST_MASK;
  
      if (length == 1) {
          /* Send NACK after receiving the next byte */
          dev->C1 |= I2C_C1_TXAK_MASK;
      }
  
      /* Initiate master receive mode by reading the data register */
      dev->D;
  
      while (length > 0) {
          while (!(dev->S & I2C_S_IICIF_MASK));
  
          dev->S = I2C_S_IICIF_MASK;
  
          if (_i2c_arbitration_lost(dev)) {
              DEBUG("i2c:_receive: arbitration lost (to go=%d)\n", length);
              return -1;
          }
  
          length--;
  
          if (length == 1) {
              /* Send NACK after receiving the next byte */
              dev->C1 |= I2C_C1_TXAK_MASK;
          }
  
          if (length == 0) {
              /* Stop immediately because the receiving of the next byte will be
               * initiated by reading the data register (dev->D). */
              dev->C1 &= ~I2C_C1_MST_MASK;
          }
  
          data[n] = dev->D;
          TRACE("i2c: rx: %02x\n", (unsigned int)data[n]);
          n++;
      }
  
      return n;
  }
  
  static inline int _i2c_transmit(I2C_Type *dev, const uint8_t *data, int length)
  {
      int n = 0;
  
      while (length > 0) {
          TRACE("i2c: tx: %02x\n", data[n]);
          dev->D = data[n];
  
          while (!(dev->S & I2C_S_IICIF_MASK));
  
          dev->S = I2C_S_IICIF_MASK;
  
          if (dev->S & I2C_S_RXAK_MASK) {
              return n;
          }
  
          n++;
          length--;
      }
  
      return n;
  }
  
  static inline void _i2c_stop(I2C_Type *dev)
  {
      /* put bus in idle state */
      dev->C1 = I2C_C1_IICEN_MASK;
  
      /* wait for bus idle */
      while (dev->S & I2C_S_BUSY_MASK);
  }
  
  static inline void _i2c_reset(I2C_Type *dev)
  {
      /* put bus in idle state */
      dev->C1 = I2C_C1_IICEN_MASK;
      /* reset status flags */
      dev->S = I2C_S_ARBL_MASK | I2C_S_IICIF_MASK;
  }
  
  
  int i2c_read_byte(i2c_t dev, uint8_t address, void *data)
  {
      return i2c_read_bytes(dev, address, data, 1);
  }
  
  int i2c_read_bytes(i2c_t dev, uint8_t address, void *data, int length)
  {
      I2C_Type *i2c;
      int n = 0;
  
      switch (dev) {
  #if I2C_0_EN
  
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      if (_i2c_start(i2c, address, I2C_FLAG_READ)) {
          _i2c_reset(i2c);
          return -1;
      }
  
      n = _i2c_receive(i2c, (uint8_t *)data, length);
      if (n < 0) {
          _i2c_reset(i2c);
          return -1;
      }
  
      _i2c_stop(i2c);
  
      return n;
  }
  
  int i2c_write_byte(i2c_t dev, uint8_t address, uint8_t data)
  {
      return i2c_write_bytes(dev, address, &data, 1);
  }
  
  int i2c_write_bytes(i2c_t dev, uint8_t address, const void *data, int length)
  {
      I2C_Type *i2c;
      int n = 0;
  
      switch (dev) {
  #if I2C_0_EN
  
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
          _i2c_reset(i2c);
          return -1;
      }
  
      n = _i2c_transmit(i2c, data, length);
      _i2c_stop(i2c);
  
      return n;
  }
  
  int i2c_read_reg(i2c_t dev, uint8_t address, uint8_t reg, void *data)
  {
      return i2c_read_regs(dev, address, reg, data, 1);
  
  }
  
  int i2c_read_regs(i2c_t dev, uint8_t address, uint8_t reg, void *data, int length)
  {
      I2C_Type *i2c;
      int n = 0;
  
      switch (dev) {
  #if I2C_0_EN
  
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
          _i2c_reset(i2c);
          return -1;
      }
  
      /* send reg */
      n = _i2c_transmit(i2c, &reg, 1);
  
      if (!n) {
          _i2c_stop(i2c);
          return n;
      }
  
      if (_i2c_restart(i2c, address, I2C_FLAG_READ)) {
          _i2c_reset(i2c);
          return -1;
      }
  
      n = _i2c_receive(i2c, (uint8_t *)data, length);
      if (n < 0) {
          _i2c_reset(i2c);
          return -1;
      }
  
      _i2c_stop(i2c);
  
      return n;
  }
  
  int i2c_write_reg(i2c_t dev, uint8_t address, uint8_t reg, uint8_t data)
  {
      return i2c_write_regs(dev, address, reg, &data, 1);
  }
  
  int i2c_write_regs(i2c_t dev, uint8_t address, uint8_t reg, const void *data, int length)
  {
      I2C_Type *i2c;
      int n = 0;
  
      switch (dev) {
  #if I2C_0_EN
  
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
          _i2c_reset(i2c);
          return -1;
      }
  
      n = _i2c_transmit(i2c, &reg, 1);
  
      if (!n) {
          _i2c_stop(i2c);
          return n;
      }
  
      n = _i2c_transmit(i2c, data, length);
      _i2c_stop(i2c);
  
      return n;
  }
  
  void i2c_poweron(i2c_t dev)
  {
      switch (dev) {
  #if I2C_0_EN
  
          case I2C_0:
              I2C_0_CLKEN();
              break;
  #endif
      }
  }
  
  void i2c_poweroff(i2c_t dev)
  {
      switch (dev) {
  #if I2C_0_EN
  
          case I2C_0:
              I2C_0_CLKDIS();
              break;
  #endif
      }
  }
  
  #endif /* I2C_NUMOF */