text: /*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2016 Scott Shawcroft
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include "shared-bindings/busio/I2C.h"
  #include "py/mperrno.h"
  #include "py/runtime.h"
  
  #include "hal/include/hal_gpio.h"
  #include "hal/include/hal_i2c_m_sync.h"
  #include "hal/include/hpl_i2c_m_sync.h"
  
  #include "samd/sercom.h"
  #include "shared-bindings/microcontroller/__init__.h"
  #include "supervisor/shared/translate.h"
  
  #include "common-hal/busio/SPI.h" // for never_reset_sercom
  
  // Number of times to try to send packet if failed.
  #define ATTEMPTS 2
  
  Sercom *samd_i2c_get_sercom(const mcu_pin_obj_t* scl, const mcu_pin_obj_t* sda,
                              uint8_t *sercom_index, uint32_t *sda_pinmux, uint32_t *scl_pinmux) {
      *sda_pinmux = 0;
      *scl_pinmux = 0;
      for (int i = 0; i < NUM_SERCOMS_PER_PIN; i++) {
          *sercom_index = sda->sercom[i].index;
          if (*sercom_index >= SERCOM_INST_NUM) {
              continue;
          }
          Sercom* potential_sercom = sercom_insts[*sercom_index];
          if (potential_sercom->I2CM.CTRLA.bit.ENABLE != 0 ||
              sda->sercom[i].pad != 0) {
              continue;
          }
          *sda_pinmux = PINMUX(sda->number, (i == 0) ? MUX_C : MUX_D);
          for (int j = 0; j < NUM_SERCOMS_PER_PIN; j++) {
              if (*sercom_index == scl->sercom[j].index &&
                  scl->sercom[j].pad == 1) {
                  *scl_pinmux = PINMUX(scl->number, (j == 0) ? MUX_C : MUX_D);
                  return potential_sercom;
              }
          }
      }
      return NULL;
  }
  
  void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
          const mcu_pin_obj_t* scl, const mcu_pin_obj_t* sda, uint32_t frequency, uint32_t timeout) {
      uint8_t sercom_index;
      uint32_t sda_pinmux, scl_pinmux;
      Sercom* sercom = samd_i2c_get_sercom(scl, sda, &sercom_index, &sda_pinmux, &scl_pinmux);
      if (sercom == NULL) {
          mp_raise_ValueError(translate("Invalid pins"));
      }
  
      // Test that the pins are in a high state. (Hopefully indicating they are pulled up.)
      gpio_set_pin_function(sda->number, GPIO_PIN_FUNCTION_OFF);
      gpio_set_pin_function(scl->number, GPIO_PIN_FUNCTION_OFF);
      gpio_set_pin_direction(sda->number, GPIO_DIRECTION_IN);
      gpio_set_pin_direction(scl->number, GPIO_DIRECTION_IN);
  
      gpio_set_pin_pull_mode(sda->number, GPIO_PULL_DOWN);
      gpio_set_pin_pull_mode(scl->number, GPIO_PULL_DOWN);
  
      common_hal_mcu_delay_us(10);
  
      gpio_set_pin_pull_mode(sda->number, GPIO_PULL_OFF);
      gpio_set_pin_pull_mode(scl->number, GPIO_PULL_OFF);
  
      // We must pull up within 3us to achieve 400khz.
      common_hal_mcu_delay_us(3);
  
      if (!gpio_get_pin_level(sda->number) || !gpio_get_pin_level(scl->number)) {
          reset_pin_number(sda->number);
          reset_pin_number(scl->number);
          mp_raise_RuntimeError(translate("SDA or SCL needs a pull up"));
      }
      gpio_set_pin_function(sda->number, sda_pinmux);
      gpio_set_pin_function(scl->number, scl_pinmux);
  
      // Set up I2C clocks on sercom.
      samd_peripherals_sercom_clock_init(sercom, sercom_index);
  
      if (i2c_m_sync_init(&self->i2c_desc, sercom) != ERR_NONE) {
          reset_pin_number(sda->number);
          reset_pin_number(scl->number);
          mp_raise_OSError(MP_EIO);
      }
  
      // clkrate is always 0. baud_rate is in kHz.
  
      // Frequency must be set before the I2C device is enabled.
      if (i2c_m_sync_set_baudrate(&self->i2c_desc, 0, frequency / 1000) != ERR_NONE) {
          reset_pin_number(sda->number);
          reset_pin_number(scl->number);
          mp_raise_ValueError(translate("Unsupported baudrate"));
      }
  
      self->sda_pin = sda->number;
      self->scl_pin = scl->number;
      claim_pin(sda);
      claim_pin(scl);
  
      if (i2c_m_sync_enable(&self->i2c_desc) != ERR_NONE) {
          common_hal_busio_i2c_deinit(self);
          mp_raise_OSError(MP_EIO);
      }
  }
  
  bool common_hal_busio_i2c_deinited(busio_i2c_obj_t *self) {
      return self->sda_pin == NO_PIN;
  }
  
  void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
      if (common_hal_busio_i2c_deinited(self)) {
          return;
      }
  
      i2c_m_sync_disable(&self->i2c_desc);
      i2c_m_sync_deinit(&self->i2c_desc);
  
      reset_pin_number(self->sda_pin);
      reset_pin_number(self->scl_pin);
      self->sda_pin = NO_PIN;
      self->scl_pin = NO_PIN;
  }
  
  bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
      struct io_descriptor *i2c_io;
      i2c_m_sync_get_io_descriptor(&self->i2c_desc, &i2c_io);
      i2c_m_sync_set_slaveaddr(&self->i2c_desc, addr, I2C_M_SEVEN);
  
      // Write no data when just probing
      return io_write(i2c_io, NULL, 0) == ERR_NONE;
  }
  
  bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
      bool grabbed_lock = false;
      CRITICAL_SECTION_ENTER()
          if (!self->has_lock) {
              grabbed_lock = true;
              self->has_lock = true;
          }
      CRITICAL_SECTION_LEAVE();
      return grabbed_lock;
  }
  
  bool common_hal_busio_i2c_has_lock(busio_i2c_obj_t *self) {
      return self->has_lock;
  }
  
  void common_hal_busio_i2c_unlock(busio_i2c_obj_t *self) {
      self->has_lock = false;
  }
  
  uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr,
                                     const uint8_t *data, size_t len, bool transmit_stop_bit) {
  
      uint16_t attempts = ATTEMPTS;
      int32_t status;
      do {
          struct _i2c_m_msg msg;
          msg.addr = addr;
          msg.len = len;
          msg.flags  = transmit_stop_bit ? I2C_M_STOP : 0;
          msg.buffer = (uint8_t *) data;
          status = _i2c_m_sync_transfer(&self->i2c_desc.device, &msg);
  
          // Give up after ATTEMPTS tries.
          if (--attempts == 0) {
              break;
          }
      } while (status != I2C_OK);
      if (status == I2C_OK) {
          return 0;
      } else if (status == I2C_ERR_BAD_ADDRESS) {
          return MP_ENODEV;
      }
      return MP_EIO;
  }
  
  uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr,
          uint8_t *data, size_t len) {
  
      uint16_t attempts = ATTEMPTS;
      int32_t status;
      do {
          struct _i2c_m_msg msg;
  	msg.addr   = addr;
  	msg.len    = len;
  	msg.flags  = I2C_M_STOP | I2C_M_RD;
  	msg.buffer = data;
          status = _i2c_m_sync_transfer(&self->i2c_desc.device, &msg);
  
          // Give up after ATTEMPTS tries.
          if (--attempts == 0) {
              break;
          }
      } while (status != I2C_OK);
      if (status == ERR_NONE) {
          return 0;
      } else if (status == I2C_ERR_BAD_ADDRESS) {
          return MP_ENODEV;
      }
      return MP_EIO;
  }
  
  void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
      never_reset_sercom(self->i2c_desc.device.hw);
  
      never_reset_pin_number(self->scl_pin);
      never_reset_pin_number(self->sda_pin);
  }
  