pw_spi/public/pw_spi/chip_selector.h

// Copyright 2021 The Pigweed Authors
//
// 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
//
//     https://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.

#pragma once

#include <cstdint>

#include "pw_status/status.h"

namespace pw::spi {

// Configuration data used to determine how the Chip Select signal is controlled
// throughout a transaction.
// `kPerWriteRead` indicates that the chip-select signal should be
// activated/deactivated between calls to WriteRead()
enum class ChipSelectBehavior : uint8_t {
  kPerWriteRead,
  kPerTransaction,
};

// The ChipSelector class provides an abstract interface for controlling the
// chip-select signal associated with a specific SPI peripheral.
class ChipSelector {
 public:
  virtual ~ChipSelector() = default;

  // SetActive sets the state of the chip-select signal to the value represented
  // by the `active` parameter.  Passing a value of `true` will activate the
  // chip-select signal, and `false` will deactive the chip-select signal.
  // Returns OkStatus() on success, and implementation-specific values on
  // failure.
  virtual Status SetActive(bool active) = 0;

  // Helper method to activate the chip-select signal
  // Returns OkStatus() on success, and implementation-specific values on
  // failure.
  Status Activate() { return SetActive(true); }

  // Helper method to deactivate the chip-select signal
  // Returns OkStatus() on success, and implementation-specific values on
  // failure.
  Status Deactivate() { return SetActive(false); }
};

}  // namespace pw::spi