// Copyright 2019 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BIOD_EC_COMMAND_H_
#define BIOD_EC_COMMAND_H_

#include <sys/ioctl.h>

#include <cerrno>
#include <cstddef>
#include <cstdint>
#include <limits>

#include <base/logging.h>
#include <base/macros.h>
#include <chromeos/ec/cros_ec_dev.h>

namespace biod {

enum class EcCmdVersionSupportStatus {
  UNKNOWN = 0,
  SUPPORTED = 1,
  UNSUPPORTED = 2,
};

// Empty request or response for the EcCommand template below.
struct EmptyParam {};
// empty struct is one byte in C++, get the size we want instead.
template <typename T>
constexpr size_t realsizeof() {
  return std::is_empty<T>::value ? 0 : sizeof(T);
}

constexpr uint32_t kVersionZero = 0;
constexpr uint32_t kVersionOne = 1;

static constexpr auto kEcCommandUninitializedResult =
    std::numeric_limits<uint32_t>::max();

class EcCommandInterface {
 public:
  virtual ~EcCommandInterface() = default;
  virtual bool Run(int fd) = 0;
  virtual uint32_t Version() const = 0;
  virtual uint32_t Command() const = 0;
};

// Helper to build and send the command structures for cros_fp.
template <typename O, typename I>
class EcCommand : public EcCommandInterface {
 public:
  explicit EcCommand(uint32_t cmd, uint32_t ver = 0, const O& req = {})
      : data_({
            .cmd = {.version = ver,
                    .command = cmd,
                    .outsize = realsizeof<O>(),
                    .insize = realsizeof<I>(),
                    .result = kEcCommandUninitializedResult},
            .req = req,
        }) {}
  ~EcCommand() override = default;

  void SetRespSize(uint32_t insize) { data_.cmd.insize = insize; }
  void SetReqSize(uint32_t outsize) { data_.cmd.outsize = outsize; }
  void SetReq(const O& req) { data_.req = req; }

  /**
   * Run an EC command.
   *
   * @param ec_fd file descriptor for the EC device
   * @return true if command runs successfully and response size is same as
   * expected, false otherwise
   *
   * The caller must be careful to only retry EC state-less
   * commands, that can be rerun without consequence.
   */
  bool Run(int ec_fd) override {
    data_.cmd.result = kEcCommandUninitializedResult;

    // We rely on the ioctl preserving data_.req when the command fails.
    // This is important for subsequent retries using the same data_.req.
    int ret = ioctl(ec_fd, CROS_EC_DEV_IOCXCMD_V2, &data_);
    if (ret < 0) {
      // If the ioctl fails for some reason let's make sure that the driver
      // didn't touch the result.
      data_.cmd.result = kEcCommandUninitializedResult;
      PLOG(ERROR) << "FPMCU ioctl command 0x" << std::hex << data_.cmd.command
                  << std::dec << " failed";
      return false;
    }

    return (static_cast<uint32_t>(ret) == data_.cmd.insize);
  }

  bool RunWithMultipleAttempts(int fd, int num_attempts) {
    for (int retry = 0; retry < num_attempts; retry++) {
      bool ret = Run(fd);

      if (ret) {
        LOG_IF(INFO, retry > 0)
            << "FPMCU ioctl command 0x" << std::hex << data_.cmd.command
            << std::dec << " succeeded on attempt " << retry + 1 << "/"
            << num_attempts << ".";
        return true;
      }

      // If we just want to check the supported version of a command, and the
      // command does not exist, do not emit error in the log and do not retry.
      if (data_.cmd.command == EC_CMD_GET_CMD_VERSIONS &&
          data_.cmd.result == EC_RES_INVALID_PARAM)
        return false;

      if (errno != ETIMEDOUT) {
        LOG(ERROR) << "FPMCU ioctl command 0x" << std::hex << data_.cmd.command
                   << std::dec << " failed on attempt " << retry + 1 << "/"
                   << num_attempts << ", retry is not allowed for error";
        return false;
      }

      LOG(ERROR) << "FPMCU ioctl command 0x" << std::hex << data_.cmd.command
                 << std::dec << " failed on attempt " << retry + 1 << "/"
                 << num_attempts;
    }
    return false;
  }

  I* Resp() { return &data_.resp; }
  uint32_t RespSize() const { return data_.cmd.insize; }
  O* Req() { return &data_.req; }
  uint32_t Result() const { return data_.cmd.result; }

  uint32_t Version() const override { return data_.cmd.version; }
  uint32_t Command() const override { return data_.cmd.command; }

  struct Data {
    struct cros_ec_command_v2 cmd;
    union {
      O req;
      I resp;
    };
  };

 protected:
  Data data_;

 private:
  virtual int ioctl(int fd, uint32_t request, Data* data) {
    return ::ioctl(fd, request, data);
  }

  DISALLOW_COPY_AND_ASSIGN(EcCommand);
};

}  // namespace biod

#endif  // BIOD_EC_COMMAND_H_