system/dev/thermal/aml-thermal-s905d2g/aml-voltage.cpp

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "aml-voltage.h"
#include <ddk/debug.h>
#include <unistd.h>
#include <string.h>

namespace thermal {

namespace {

// Sleep for 200 microseconds inorder to let the voltage change
// take effect. Source: Amlogic SDK.
constexpr uint32_t kSleep = 200;
// Step up or down 3 steps in the voltage table while changing
// voltage and not directly. Source: Amlogic SDK
constexpr int kSteps = 3;
// Invalid index in the voltage-table
constexpr int kInvalidIndex = -1;

} // namespace

zx_status_t AmlVoltageRegulator::Init(zx_device_t* parent, opp_info_t* opp_info) {
    ZX_DEBUG_ASSERT(opp_info);

    // Create a PWM period = 1250, hwpwm - 1 to signify using PWM_D from PWM_C/D.
    // Source: Amlogic SDK.
    fbl::AllocChecker ac;
    pwm_ = fbl::make_unique_checked<AmlPwm>(&ac, 1250, 1);
    if (!ac.check()) {
        return ZX_ERR_NO_MEMORY;
    }

    // Initialize the PWM.
    zx_status_t status = pwm_->Init(parent);
    if (status != ZX_OK) {
        zxlogf(ERROR, "aml-voltage: Could not inititalize PWM: %d\n", status);
        return status;
    }

    // Get the voltage-table metadata.
    memcpy(&opp_info_, opp_info, sizeof(opp_info_t));

    current_voltage_index_ = kInvalidIndex;

    // Set the voltage to maximum to start with
    // TODO(braval):  Figure out a better way to set initialize
    //.               voltage.
    status = SetVoltage(981000);
    return ZX_OK;
}

zx_status_t AmlVoltageRegulator::SetVoltage(uint32_t microvolt) {
    // Find the entry in the voltage-table.
    int target_index;
    for (target_index = 0; target_index < MAX_VOLTAGE_TABLE; target_index++) {
        if (opp_info_.voltage_table[target_index].microvolt == microvolt) {
            break;
        }
    }

    // Invalid voltage request.
    if (target_index == MAX_VOLTAGE_TABLE) {
        return ZX_ERR_INVALID_ARGS;
    }

    zx_status_t status;
    // If this is the first time we are setting up the voltage
    // we directly set it.
    if (current_voltage_index_ < 0) {
        // Update new duty cycle.
        status = pwm_->Configure(opp_info_.voltage_table[target_index].duty_cycle);
        if (status != ZX_OK) {
            zxlogf(ERROR, "aml-voltage: Failed to set bew duty_cycle %d\n", status);
            return status;
        }
        usleep(kSleep);
        current_voltage_index_ = target_index;
        return ZX_OK;
    }

    // Otherwise we adjust to the target voltage step by step.
    while (current_voltage_index_ != target_index) {
        if (current_voltage_index_ < target_index) {
            if (current_voltage_index_ < target_index - kSteps) {
                // Step up by 3 in the voltage table.
                current_voltage_index_ += kSteps;
            } else {
                current_voltage_index_ = target_index;
            }
        } else {
            if (current_voltage_index_ > target_index + kSteps) {
                // Step down by 3 in the voltage table.
                current_voltage_index_ -= kSteps;
            } else {
                current_voltage_index_ = target_index;
            }
        }
        // Update new duty cycle.
        status = pwm_->Configure(opp_info_.voltage_table[target_index].duty_cycle);
        if (status != ZX_OK) {
            zxlogf(ERROR, "aml-voltage: Failed to set bew duty_cycle %d\n", status);
            return status;
        }
        usleep(kSleep);
    }

    // Update the current voltage index.
    current_voltage_index_ = target_index;
    return ZX_OK;
}

uint32_t AmlVoltageRegulator::GetVoltage() {
    ZX_DEBUG_ASSERT(current_voltage_index_ != kInvalidIndex);
    return opp_info_.voltage_table[current_voltage_index_].microvolt;
}
} // namespace thermal