/* IBM_PROLOG_BEGIN_TAG                                                   */
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/* $Source: src/import/chips/p9/procedures/hwp/memory/lib/freq/cycle_time.H $ */
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/* OpenPOWER HostBoot Project                                             */
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/* IBM_PROLOG_END_TAG                                                     */

///
/// @file cycle_time.H
/// @brief cycle time (tCK) data & functions needed for CAS latency algorithm
///
// *HWP HWP Owner: Andre Marin <aamarin@us.ibm.com>
// *HWP HWP Backup: Brian Silver <bsilver@us.ibm.com>
// *HWP Team: Memory
// *HWP Level: 2
// *HWP Consumed by: HB:FSP

#ifndef _MSS_CYCLE_TIME_H_
#define _MSS_CYCLE_TIME_H_

#include <fapi2.H>
#include <memory>
#include <lib/freq/sync.H>

namespace mss
{

enum FREQ_MARGIN : std::uint64_t
{
    // -5% of 1866 MT/s
    MIN_FREQ_MARGIN = 1772,

    // +5% of 2666 MT/s
    MAX_FREQ_MARGIN = 2799,
};

///
/// @brief          Selects DIMM frequency to run based on supported system frequencies
/// @tparam         T the fapi2::TargetType for which the DIMM information exists.
/// @param[in]      target from which to get the dimm information
/// @param[in,out]  io_dimm_freq input is current dimm freq & output is next
///                 lowest dimm freq between 1866 MT/s (-5% margin)  - 2666 MT/s (+5% margin)
/// @return         FAPI2_RC_SUCCESS iff ok
/// @note           Frequency values obtained from:
/// @note           From P9 User's Manual Version 0.8 - June 08, 2015
/// @note           Memory Controller Unit - page 199 of 456
///
template< fapi2::TargetType T >
inline fapi2::ReturnCode select_supported_freq(const fapi2::Target<T>& i_target, uint64_t& io_dimm_freq)
{
    uint32_t l_min_freq = 0;
    uint32_t l_max_freq = 0;
    std::vector<uint32_t> l_freqs;

    //TK - This 5% margin was done in P8, continue for P9 ?? - AAMARIN

    // Speed bins for P9 DDR4 are 1866 MT/s -  2666 MT/s
    // Giving -5% margin for 1866 MT/s and +5% margin for 2666 MT/s
    // Error out if frequency is beyond these margins
    FAPI_ASSERT( (io_dimm_freq > MIN_FREQ_MARGIN) &&
                 (io_dimm_freq < MAX_FREQ_MARGIN),
                 fapi2::MSS_UNSUPPORTED_FREQ_CALCULATED().
                 set_DIMM_MIN_FREQ(io_dimm_freq),
                 "Unsupported frequency: %d.  DIMM Freq calculated is < 1773 or > 2799 MT/s",
                 io_dimm_freq);

    FAPI_TRY( mss::supported_freqs(i_target, l_freqs) );
    l_min_freq = *(l_freqs.begin());
    l_max_freq = *(l_freqs.end() - 1);

    // Corner case to take into account -5% margin
    if(io_dimm_freq  < l_min_freq)
    {
        io_dimm_freq = l_min_freq;
        return fapi2::FAPI2_RC_SUCCESS;
    }

    // Corner case to take into account +5% margin
    if(io_dimm_freq > l_max_freq)
    {
        io_dimm_freq = l_max_freq;
        return fapi2::FAPI2_RC_SUCCESS;
    }

    // Selects next lowest freq btw 1866 - 2666 [MT/s]
    {
        // supported_freqs sorts so upper_bound is valid.
        auto iterator = std::upper_bound(l_freqs.begin(), l_freqs.end(), io_dimm_freq);
        io_dimm_freq = *(--iterator);
    }

fapi_try_exit:
    return fapi2::current_err;
}

}// mss

#endif