text: /*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * SPDX-FileCopyrightText: Copyright (c) 2016 Damien P. George
   *
   * 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/microcontroller/__init__.h"
  #include "shared-bindings/busio/UART.h"
  
  #include "mpconfigport.h"
  #include "lib/utils/interrupt_char.h"
  #include "py/gc.h"
  #include "py/mperrno.h"
  #include "py/runtime.h"
  #include "py/stream.h"
  #include "supervisor/shared/translate.h"
  #include "supervisor/shared/tick.h"
  
  #include "hpl_sercom_config.h"
  #include "peripheral_clk_config.h"
  
  #include "hal/include/hal_gpio.h"
  #include "hal/include/hal_usart_async.h"
  #include "hal/include/hpl_usart_async.h"
  
  #include "samd/sercom.h"
  
  #define UART_DEBUG(...) (void)0
  // #define UART_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)
  
  // Do-nothing callback needed so that usart_async code will enable rx interrupts.
  // See comment below re usart_async_register_callback()
  static void usart_async_rxc_callback(const struct usart_async_descriptor *const descr) {
      // Nothing needs to be done by us.
  }
  
  void common_hal_busio_uart_construct(busio_uart_obj_t *self,
      const mcu_pin_obj_t *tx, const mcu_pin_obj_t *rx,
      const mcu_pin_obj_t *rts, const mcu_pin_obj_t *cts,
      const mcu_pin_obj_t *rs485_dir, bool rs485_invert,
      uint32_t baudrate, uint8_t bits, busio_uart_parity_t parity, uint8_t stop,
      mp_float_t timeout, uint16_t receiver_buffer_size, byte *receiver_buffer,
      bool sigint_enabled) {
  
      Sercom *sercom = NULL;
      uint8_t sercom_index = 255; // Unset index
      uint32_t rx_pinmux = 0;
      uint8_t rx_pad = 255; // Unset pad
      uint32_t tx_pinmux = 0;
      uint8_t tx_pad = 255; // Unset pad
  
      if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
          mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
      }
  
      if (bits > 8) {
          mp_raise_NotImplementedError(translate("bytes > 8 bits not supported"));
      }
  
      bool have_tx = tx != NULL;
      bool have_rx = rx != NULL;
      if (!have_tx && !have_rx) {
          mp_raise_ValueError(translate("tx and rx cannot both be None"));
      }
  
      self->baudrate = baudrate;
      self->character_bits = bits;
      self->timeout_ms = timeout * 1000;
  
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
  
      for (int i = 0; i < NUM_SERCOMS_PER_PIN; i++) {
          Sercom *potential_sercom = NULL;
          if (have_tx) {
              sercom_index = tx->sercom[i].index;
              if (sercom_index >= SERCOM_INST_NUM) {
                  continue;
              }
              potential_sercom = sercom_insts[sercom_index];
              #ifdef SAMD21
              if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
                  !(tx->sercom[i].pad == 0 ||
                    tx->sercom[i].pad == 2)) {
                  continue;
              }
              #endif
              #ifdef SAM_D5X_E5X
              if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
                  !(tx->sercom[i].pad == 0)) {
                  continue;
              }
              #endif
              tx_pinmux = PINMUX(tx->number, (i == 0) ? MUX_C : MUX_D);
              tx_pad = tx->sercom[i].pad;
              if (rx == NULL) {
                  sercom = potential_sercom;
                  break;
              }
          }
          for (int j = 0; j < NUM_SERCOMS_PER_PIN; j++) {
              if (((!have_tx && rx->sercom[j].index < SERCOM_INST_NUM &&
                    sercom_insts[rx->sercom[j].index]->USART.CTRLA.bit.ENABLE == 0) ||
                   sercom_index == rx->sercom[j].index) &&
                  rx->sercom[j].pad != tx_pad) {
                  rx_pinmux = PINMUX(rx->number, (j == 0) ? MUX_C : MUX_D);
                  rx_pad = rx->sercom[j].pad;
                  sercom = sercom_insts[rx->sercom[j].index];
                  sercom_index = rx->sercom[j].index;
                  break;
              }
          }
          if (sercom != NULL) {
              break;
          }
      }
      if (sercom == NULL) {
          mp_raise_ValueError(translate("Invalid pins"));
      }
      if (!have_tx) {
          tx_pad = 0;
          if (rx_pad == 0) {
              tx_pad = 2;
          }
      }
      if (!have_rx) {
          rx_pad = (tx_pad + 1) % 4;
      }
  
      // Set up clocks on SERCOM.
      samd_peripherals_sercom_clock_init(sercom, sercom_index);
  
      if (rx && receiver_buffer_size > 0) {
          self->buffer_length = receiver_buffer_size;
          // Initially allocate the UART's buffer in the long-lived part of the
          // heap.  UARTs are generally long-lived objects, but the "make long-
          // lived" machinery is incapable of moving internal pointers like
          // self->buffer, so do it manually.  (However, as long as internal
          // pointers like this are NOT moved, allocating the buffer
          // in the long-lived pool is not strictly necessary)
          self->buffer = (uint8_t *)gc_alloc(self->buffer_length * sizeof(uint8_t), false, true);
          if (self->buffer == NULL) {
              common_hal_busio_uart_deinit(self);
              mp_raise_msg_varg(&mp_type_MemoryError, translate("Failed to allocate RX buffer of %d bytes"), self->buffer_length * sizeof(uint8_t));
          }
      } else {
          self->buffer_length = 0;
          self->buffer = NULL;
      }
  
      if (usart_async_init(usart_desc_p, sercom, self->buffer, self->buffer_length, NULL) != ERR_NONE) {
          mp_raise_ValueError(translate("Could not initialize UART"));
      }
  
      // usart_async_init() sets a number of defaults based on a prototypical SERCOM
      // which don't necessarily match what we need. After calling it, set the values
      // specific to this instantiation of UART.
  
      // Set pads computed for this SERCOM.
      // TXPO:
      // 0x0: TX pad 0; no RTS/CTS
      // 0x1: TX pad 2; no RTS/CTS
      // 0x2: TX pad 0; RTS: pad 2, CTS: pad 3 (not used by us right now)
      // So divide by 2 to map pad to value.
      // RXPO:
      // 0x0: RX pad 0
      // 0x1: RX pad 1
      // 0x2: RX pad 2
      // 0x3: RX pad 3
  
      // Doing a group mask and set of the registers saves 60 bytes over setting the bitfields individually.
  
      sercom->USART.CTRLA.reg &= ~(SERCOM_USART_CTRLA_TXPO_Msk |
          SERCOM_USART_CTRLA_RXPO_Msk |
          SERCOM_USART_CTRLA_FORM_Msk);
      sercom->USART.CTRLA.reg |= SERCOM_USART_CTRLA_TXPO(tx_pad / 2) |
          SERCOM_USART_CTRLA_RXPO(rx_pad) |
          (parity == BUSIO_UART_PARITY_NONE ? 0 : SERCOM_USART_CTRLA_FORM(1));
  
      // Enable tx and/or rx based on whether the pins were specified.
      // CHSIZE is 0 for 8 bits, 5, 6, 7 for 5, 6, 7 bits. 1 for 9 bits, but we don't support that.
      sercom->USART.CTRLB.reg &= ~(SERCOM_USART_CTRLB_TXEN |
          SERCOM_USART_CTRLB_RXEN |
          SERCOM_USART_CTRLB_PMODE |
          SERCOM_USART_CTRLB_SBMODE |
          SERCOM_USART_CTRLB_CHSIZE_Msk);
      sercom->USART.CTRLB.reg |= (have_tx ? SERCOM_USART_CTRLB_TXEN : 0) |
          (have_rx ? SERCOM_USART_CTRLB_RXEN : 0) |
          (parity == BUSIO_UART_PARITY_ODD ? SERCOM_USART_CTRLB_PMODE : 0) |
          (stop > 1 ? SERCOM_USART_CTRLB_SBMODE : 0) |
          SERCOM_USART_CTRLB_CHSIZE(bits % 8);
  
      // Set baud rate
      common_hal_busio_uart_set_baudrate(self, baudrate);
  
      // Turn on rx interrupt handling. The UART async driver has its own set of internal callbacks,
      // which are set up by uart_async_init(). These in turn can call user-specified callbacks.
      // In fact, the actual interrupts are not enabled unless we set up a user-specified callback.
      // This is confusing. It's explained in the Atmel START User Guide -> Implementation Description ->
      // Different read function behavior in some asynchronous drivers. As of this writing:
      // http://start.atmel.com/static/help/index.html?GUID-79201A5A-226F-4FBB-B0B8-AB0BE0554836
      // Look at the ASFv4 code example for async USART.
      usart_async_register_callback(usart_desc_p, USART_ASYNC_RXC_CB, usart_async_rxc_callback);
  
  
      if (have_tx) {
          gpio_set_pin_direction(tx->number, GPIO_DIRECTION_OUT);
          gpio_set_pin_pull_mode(tx->number, GPIO_PULL_OFF);
          gpio_set_pin_function(tx->number, tx_pinmux);
          self->tx_pin = tx->number;
          claim_pin(tx);
      } else {
          self->tx_pin = NO_PIN;
      }
  
      if (have_rx) {
          gpio_set_pin_direction(rx->number, GPIO_DIRECTION_IN);
          gpio_set_pin_pull_mode(rx->number, GPIO_PULL_OFF);
          gpio_set_pin_function(rx->number, rx_pinmux);
          self->rx_pin = rx->number;
          claim_pin(rx);
      } else {
          self->rx_pin = NO_PIN;
      }
  
      usart_async_enable(usart_desc_p);
  }
  
  bool common_hal_busio_uart_deinited(busio_uart_obj_t *self) {
      return self->rx_pin == NO_PIN && self->tx_pin == NO_PIN;
  }
  
  void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
      if (common_hal_busio_uart_deinited(self)) {
          return;
      }
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
      usart_async_disable(usart_desc_p);
      usart_async_deinit(usart_desc_p);
      reset_pin_number(self->rx_pin);
      reset_pin_number(self->tx_pin);
      self->rx_pin = NO_PIN;
      self->tx_pin = NO_PIN;
  }
  
  // Read characters.
  size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t len, int *errcode) {
      if (self->rx_pin == NO_PIN) {
          mp_raise_ValueError(translate("No RX pin"));
      }
  
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
  
      if (len == 0) {
          // Nothing to read.
          return 0;
      }
  
      struct io_descriptor *io;
      usart_async_get_io_descriptor(usart_desc_p, &io);
  
      size_t total_read = 0;
      uint64_t start_ticks = supervisor_ticks_ms64();
  
      // Busy-wait until timeout or until we've read enough chars.
      while (supervisor_ticks_ms64() - start_ticks <= self->timeout_ms) {
          // Read as many chars as we can right now, up to len.
          size_t num_read = io_read(io, data, len);
  
          // Advance pointer in data buffer, and decrease how many chars left to read.
          data += num_read;
          len -= num_read;
          total_read += num_read;
          if (len == 0) {
              // Don't need to read any more: data buf is full.
              break;
          }
          if (num_read > 0) {
              // Reset the timeout on every character read.
              start_ticks = supervisor_ticks_ms64();
          }
          RUN_BACKGROUND_TASKS;
          // Allow user to break out of a timeout with a KeyboardInterrupt.
          if (mp_hal_is_interrupted()) {
              break;
          }
          // If we are zero timeout, make sure we don't loop again (in the event
          // we read in under 1ms)
          if (self->timeout_ms == 0) {
              break;
          }
      }
  
      if (total_read == 0) {
          *errcode = EAGAIN;
          return MP_STREAM_ERROR;
      }
  
      return total_read;
  }
  
  // Write characters.
  size_t common_hal_busio_uart_write(busio_uart_obj_t *self, const uint8_t *data, size_t len, int *errcode) {
      if (self->tx_pin == NO_PIN) {
          mp_raise_ValueError(translate("No TX pin"));
      }
  
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
  
      struct io_descriptor *io;
      usart_async_get_io_descriptor(usart_desc_p, &io);
  
      // Start writing characters. This is non-blocking and will
      // return immediately after setting up the write.
      if (io_write(io, data, len) < 0) {
          *errcode = MP_EAGAIN;
          return MP_STREAM_ERROR;
      }
  
      // Busy-wait until all characters transmitted.
      struct usart_async_status async_status;
      while (true) {
          usart_async_get_status(usart_desc_p, &async_status);
          if (async_status.txcnt >= len) {
              break;
          }
          RUN_BACKGROUND_TASKS;
      }
  
      return len;
  }
  
  uint32_t common_hal_busio_uart_get_baudrate(busio_uart_obj_t *self) {
      return self->baudrate;
  }
  
  void common_hal_busio_uart_set_baudrate(busio_uart_obj_t *self, uint32_t baudrate) {
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
      usart_async_set_baud_rate(usart_desc_p,
          // Samples and ARITHMETIC vs FRACTIONAL must correspond to USART_SAMPR in
          // hpl_sercom_config.h.
          _usart_async_calculate_baud_rate(baudrate,                        // e.g. 9600 baud
              PROTOTYPE_SERCOM_USART_ASYNC_CLOCK_FREQUENCY,
              16,                                                      // samples
              USART_BAUDRATE_ASYNCH_ARITHMETIC,
              0                                                     // fraction - not used for ARITHMETIC
              ));
      self->baudrate = baudrate;
  }
  
  mp_float_t common_hal_busio_uart_get_timeout(busio_uart_obj_t *self) {
      return (mp_float_t)(self->timeout_ms / 1000.0f);
  }
  
  void common_hal_busio_uart_set_timeout(busio_uart_obj_t *self, mp_float_t timeout) {
      self->timeout_ms = timeout * 1000;
  }
  
  uint32_t common_hal_busio_uart_rx_characters_available(busio_uart_obj_t *self) {
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
      struct usart_async_status async_status;
      usart_async_get_status(usart_desc_p, &async_status);
      return async_status.rxcnt;
  }
  
  void common_hal_busio_uart_clear_rx_buffer(busio_uart_obj_t *self) {
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
      usart_async_flush_rx_buffer(usart_desc_p);
  
  }
  
  // True if there are no characters still to be written.
  bool common_hal_busio_uart_ready_to_tx(busio_uart_obj_t *self) {
      if (self->tx_pin == NO_PIN) {
          return false;
      }
      // This assignment is only here because the usart_async routines take a *const argument.
      struct usart_async_descriptor *const usart_desc_p = (struct usart_async_descriptor *const)&self->usart_desc;
      struct usart_async_status async_status;
      usart_async_get_status(usart_desc_p, &async_status);
      return !(async_status.flags & USART_ASYNC_STATUS_BUSY);
  }
  