functions.cpp

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// Copyright (c) 2024 anabrid GmbH
// Contact: https://www.anabrid.com/licensing/
// SPDX-License-Identifier: MIT OR GPL-2.0-or-later
 
#include <bus/functions.h>
 
functions::Function::Function(const bus::addr_t address) : address(address) {}
 
void functions::TriggerFunction::trigger(uint32_t pulse_length_ns) const {
  bus::address_function(address);
  bus::activate_address();
 
  delayNanoseconds(pulse_length_ns);
  digitalWriteFast(bus::PIN_CSEL, LOW);
 
  delayNanoseconds(2 * 42);
 
  delayNanoseconds(pulse_length_ns);
  digitalWriteFast(bus::PIN_CSEL, HIGH);
 
  bus::deactivate_address();
}
 
functions::DataFunction::DataFunction(bus::addr_t address, uint8_t alt_function_idx,
                                      const SPISettings &spiSettings)
    : Function(address),
      alt_function_address(bus::replace_function_idx(address, alt_function_idx)),
      use_csel(alt_function_idx == 0xff),
      spi_settings(spiSettings) {}
 
void functions::DataFunction::begin_communication() const {
  /*
   * HACK: Do two-step addressing to circumvent hardware limitations,
   *       see lucidac/hardware/dimm-template-rev1/-/issues/2
   *
   * For each block, we have to define an unused (or practically no-op) address that
   * gets addressed first to assert the correct MSELECT signal, before we address
   * the actual address. Otherwise, the SPI mode can not be correctly set.
   * Each block requires different addresses. See the issue for background info.
   */
 
  if (!use_csel) {
    bus::address_function(alt_function_address);
    bus::activate_address();
    bus::address_function(address);
    bus::spi.beginTransaction(spi_settings);
    delayNanoseconds(200);
    bus::activate_address();
  } else {
    bus::address_function(address);
    bus::spi.beginTransaction(spi_settings);
    delayNanoseconds(200);
    bus::activate_address();
  }
  delayNanoseconds(200);
  digitalWriteFast(bus::PIN_CSEL, LOW);
  delayNanoseconds(200);
}
 
void functions::DataFunction::end_communication() const {
  delayNanoseconds(20);
  digitalWriteFast(bus::PIN_CSEL, HIGH);
  delayNanoseconds(200);
  bus::deactivate_address();
  bus::spi.endTransaction();
}
 
void functions::DataFunction::transfer(const void *mosi_buf, void *miso_buf, size_t count) const {
  begin_communication();
  bus::spi.transfer(mosi_buf, miso_buf, count);
  end_communication();
}
 
uint8_t functions::DataFunction::transfer8(uint8_t data_in) const {
  begin_communication();
  auto ret = bus::spi.transfer(data_in);
  end_communication();
  return ret;
}
 
uint16_t functions::DataFunction::transfer16(uint16_t data_in) const {
  begin_communication();
  auto ret = bus::spi.transfer16(data_in);
  end_communication();
  return ret;
}
 
uint32_t functions::DataFunction::transfer32(uint32_t data_in) const {
  begin_communication();
  auto ret = bus::spi.transfer32(data_in);
  end_communication();
  return ret;
}
 
SPIClass &functions::DataFunction::get_raw_spi() { return bus::spi; }