/*
 * Copyright(c) 2015, 2016 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/firmware.h>

#include "hfi.h"
#include "efivar.h"
#include "eprom.h"

#define DEFAULT_PLATFORM_CONFIG_NAME "hfi1_platform.dat"

static int validate_scratch_checksum(struct hfi1_devdata *dd)
{
        u64 checksum = 0, temp_scratch = 0;
        int i, j, version;

        temp_scratch = read_csr(dd, ASIC_CFG_SCRATCH);
        version = (temp_scratch & BITMAP_VERSION_SMASK) >> BITMAP_VERSION_SHIFT;

        /* Prevent power on default of all zeroes from passing checksum */
        if (!version) {
                dd_dev_err(dd, "%s: Config bitmap uninitialized\n", __func__);
                dd_dev_err(dd,
                           "%s: Please update your BIOS to support active channels\n",
                           __func__);
                return 0;
        }

        /*
         * ASIC scratch 0 only contains the checksum and bitmap version as
         * fields of interest, both of which are handled separately from the
         * loop below, so skip it
         */
        checksum += version;
        for (i = 1; i < ASIC_NUM_SCRATCH; i++) {
                temp_scratch = read_csr(dd, ASIC_CFG_SCRATCH + (8 * i));
                for (j = sizeof(u64); j != 0; j -= 2) {
                        checksum += (temp_scratch & 0xFFFF);
                        temp_scratch >>= 16;
                }
        }

        while (checksum >> 16)
                checksum = (checksum & CHECKSUM_MASK) + (checksum >> 16);

        temp_scratch = read_csr(dd, ASIC_CFG_SCRATCH);
        temp_scratch &= CHECKSUM_SMASK;
        temp_scratch >>= CHECKSUM_SHIFT;

        if (checksum + temp_scratch == 0xFFFF)
                return 1;

        dd_dev_err(dd, "%s: Configuration bitmap corrupted\n", __func__);
        return 0;
}

static void save_platform_config_fields(struct hfi1_devdata *dd)
{
        struct hfi1_pportdata *ppd = dd->pport;
        u64 temp_scratch = 0, temp_dest = 0;

        temp_scratch = read_csr(dd, ASIC_CFG_SCRATCH_1);

        temp_dest = temp_scratch &
                    (dd->hfi1_id ? PORT1_PORT_TYPE_SMASK :
                     PORT0_PORT_TYPE_SMASK);
        ppd->port_type = temp_dest >>
                         (dd->hfi1_id ? PORT1_PORT_TYPE_SHIFT :
                          PORT0_PORT_TYPE_SHIFT);

        temp_dest = temp_scratch &
                    (dd->hfi1_id ? PORT1_LOCAL_ATTEN_SMASK :
                     PORT0_LOCAL_ATTEN_SMASK);
        ppd->local_atten = temp_dest >>
                           (dd->hfi1_id ? PORT1_LOCAL_ATTEN_SHIFT :
                            PORT0_LOCAL_ATTEN_SHIFT);

        temp_dest = temp_scratch &
                    (dd->hfi1_id ? PORT1_REMOTE_ATTEN_SMASK :
                     PORT0_REMOTE_ATTEN_SMASK);
        ppd->remote_atten = temp_dest >>
                            (dd->hfi1_id ? PORT1_REMOTE_ATTEN_SHIFT :
                             PORT0_REMOTE_ATTEN_SHIFT);

        temp_dest = temp_scratch &
                    (dd->hfi1_id ? PORT1_DEFAULT_ATTEN_SMASK :
                     PORT0_DEFAULT_ATTEN_SMASK);
        ppd->default_atten = temp_dest >>
                             (dd->hfi1_id ? PORT1_DEFAULT_ATTEN_SHIFT :
                              PORT0_DEFAULT_ATTEN_SHIFT);

        temp_scratch = read_csr(dd, dd->hfi1_id ? ASIC_CFG_SCRATCH_3 :
                                ASIC_CFG_SCRATCH_2);

        ppd->tx_preset_eq = (temp_scratch & TX_EQ_SMASK) >> TX_EQ_SHIFT;
        ppd->tx_preset_noeq = (temp_scratch & TX_NO_EQ_SMASK) >> TX_NO_EQ_SHIFT;
        ppd->rx_preset = (temp_scratch & RX_SMASK) >> RX_SHIFT;

        ppd->max_power_class = (temp_scratch & QSFP_MAX_POWER_SMASK) >>
                                QSFP_MAX_POWER_SHIFT;

        ppd->config_from_scratch = true;
}

void get_platform_config(struct hfi1_devdata *dd)
{
        int ret = 0;
        u8 *temp_platform_config = NULL;
        u32 esize;
        const struct firmware *platform_config_file = NULL;

        if (is_integrated(dd)) {
                if (validate_scratch_checksum(dd)) {
                        save_platform_config_fields(dd);
                        return;
                }
        } else {
                ret = eprom_read_platform_config(dd,
                                                 (void **)&temp_platform_config,
                                                 &esize);
                if (!ret) {
                        /* success */
                        dd->platform_config.data = temp_platform_config;
                        dd->platform_config.size = esize;
                        return;
                }
        }
        dd_dev_err(dd,
                   "%s: Failed to get platform config, falling back to sub-optimal default file\n",
                   __func__);

        ret = request_firmware(&platform_config_file,
                               DEFAULT_PLATFORM_CONFIG_NAME,
                               &dd->pcidev->dev);
        if (ret) {
                dd_dev_err(dd,
                           "%s: No default platform config file found\n",
                           __func__);
                return;
        }

        /*
         * Allocate separate memory block to store data and free firmware
         * structure. This allows free_platform_config to treat EPROM and
         * fallback configs in the same manner.
         */
        dd->platform_config.data = kmemdup(platform_config_file->data,
                                           platform_config_file->size,
                                           GFP_KERNEL);
        dd->platform_config.size = platform_config_file->size;
        release_firmware(platform_config_file);
}

void free_platform_config(struct hfi1_devdata *dd)
{
        /* Release memory allocated for eprom or fallback file read. */
        kfree(dd->platform_config.data);
        dd->platform_config.data = NULL;
}

void get_port_type(struct hfi1_pportdata *ppd)
{
        int ret;
        u32 temp;

        ret = get_platform_config_field(ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                                        PORT_TABLE_PORT_TYPE, &temp,
                                        4);
        if (ret) {
                ppd->port_type = PORT_TYPE_UNKNOWN;
                return;
        }
        ppd->port_type = temp;
}

int set_qsfp_tx(struct hfi1_pportdata *ppd, int on)
{
        u8 tx_ctrl_byte = on ? 0x0 : 0xF;
        int ret = 0;

        ret = qsfp_write(ppd, ppd->dd->hfi1_id, QSFP_TX_CTRL_BYTE_OFFS,
                         &tx_ctrl_byte, 1);
        /* we expected 1, so consider 0 an error */
        if (ret == 0)
                ret = -EIO;
        else if (ret == 1)
                ret = 0;
        return ret;
}

static int qual_power(struct hfi1_pportdata *ppd)
{
        u32 cable_power_class = 0, power_class_max = 0;
        u8 *cache = ppd->qsfp_info.cache;
        int ret = 0;

        ret = get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_SYSTEM_TABLE, 0,
                SYSTEM_TABLE_QSFP_POWER_CLASS_MAX, &power_class_max, 4);
        if (ret)
                return ret;

        cable_power_class = get_qsfp_power_class(cache[QSFP_MOD_PWR_OFFS]);

        if (cable_power_class > power_class_max)
                ppd->offline_disabled_reason =
                        HFI1_ODR_MASK(OPA_LINKDOWN_REASON_POWER_POLICY);

        if (ppd->offline_disabled_reason ==
                        HFI1_ODR_MASK(OPA_LINKDOWN_REASON_POWER_POLICY)) {
                dd_dev_err(
                        ppd->dd,
                        "%s: Port disabled due to system power restrictions\n",
                        __func__);
                ret = -EPERM;
        }
        return ret;
}

static int qual_bitrate(struct hfi1_pportdata *ppd)
{
        u16 lss = ppd->link_speed_supported, lse = ppd->link_speed_enabled;
        u8 *cache = ppd->qsfp_info.cache;

        if ((lss & OPA_LINK_SPEED_25G) && (lse & OPA_LINK_SPEED_25G) &&
            cache[QSFP_NOM_BIT_RATE_250_OFFS] < 0x64)
                ppd->offline_disabled_reason =
                           HFI1_ODR_MASK(OPA_LINKDOWN_REASON_LINKSPEED_POLICY);

        if ((lss & OPA_LINK_SPEED_12_5G) && (lse & OPA_LINK_SPEED_12_5G) &&
            cache[QSFP_NOM_BIT_RATE_100_OFFS] < 0x7D)
                ppd->offline_disabled_reason =
                           HFI1_ODR_MASK(OPA_LINKDOWN_REASON_LINKSPEED_POLICY);

        if (ppd->offline_disabled_reason ==
                        HFI1_ODR_MASK(OPA_LINKDOWN_REASON_LINKSPEED_POLICY)) {
                dd_dev_err(
                        ppd->dd,
                        "%s: Cable failed bitrate check, disabling port\n",
                        __func__);
                return -EPERM;
        }
        return 0;
}

static int set_qsfp_high_power(struct hfi1_pportdata *ppd)
{
        u8 cable_power_class = 0, power_ctrl_byte = 0;
        u8 *cache = ppd->qsfp_info.cache;
        int ret;

        cable_power_class = get_qsfp_power_class(cache[QSFP_MOD_PWR_OFFS]);

        if (cable_power_class > QSFP_POWER_CLASS_1) {
                power_ctrl_byte = cache[QSFP_PWR_CTRL_BYTE_OFFS];

                power_ctrl_byte |= 1;
                power_ctrl_byte &= ~(0x2);

                ret = qsfp_write(ppd, ppd->dd->hfi1_id,
                                 QSFP_PWR_CTRL_BYTE_OFFS,
                                 &power_ctrl_byte, 1);
                if (ret != 1)
                        return -EIO;

                if (cable_power_class > QSFP_POWER_CLASS_4) {
                        power_ctrl_byte |= (1 << 2);
                        ret = qsfp_write(ppd, ppd->dd->hfi1_id,
                                         QSFP_PWR_CTRL_BYTE_OFFS,
                                         &power_ctrl_byte, 1);
                        if (ret != 1)
                                return -EIO;
                }

                /* SFF 8679 rev 1.7 LPMode Deassert time */
                msleep(300);
        }
        return 0;
}

static void apply_rx_cdr(struct hfi1_pportdata *ppd,
                         u32 rx_preset_index,
                         u8 *cdr_ctrl_byte)
{
        u32 rx_preset;
        u8 *cache = ppd->qsfp_info.cache;
        int cable_power_class;

        if (!((cache[QSFP_MOD_PWR_OFFS] & 0x4) &&
              (cache[QSFP_CDR_INFO_OFFS] & 0x40)))
                return;

        /* RX CDR present, bypass supported */
        cable_power_class = get_qsfp_power_class(cache[QSFP_MOD_PWR_OFFS]);

        if (cable_power_class <= QSFP_POWER_CLASS_3) {
                /* Power class <= 3, ignore config & turn RX CDR on */
                *cdr_ctrl_byte |= 0xF;
                return;
        }

        get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_RX_PRESET_TABLE,
                rx_preset_index, RX_PRESET_TABLE_QSFP_RX_CDR_APPLY,
                &rx_preset, 4);

        if (!rx_preset) {
                dd_dev_info(
                        ppd->dd,
                        "%s: RX_CDR_APPLY is set to disabled\n",
                        __func__);
                return;
        }
        get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_RX_PRESET_TABLE,
                rx_preset_index, RX_PRESET_TABLE_QSFP_RX_CDR,
                &rx_preset, 4);

        /* Expand cdr setting to all 4 lanes */
        rx_preset = (rx_preset | (rx_preset << 1) |
                        (rx_preset << 2) | (rx_preset << 3));

        if (rx_preset) {
                *cdr_ctrl_byte |= rx_preset;
        } else {
                *cdr_ctrl_byte &= rx_preset;
                /* Preserve current TX CDR status */
                *cdr_ctrl_byte |= (cache[QSFP_CDR_CTRL_BYTE_OFFS] & 0xF0);
        }
}

static void apply_tx_cdr(struct hfi1_pportdata *ppd,
                         u32 tx_preset_index,
                         u8 *cdr_ctrl_byte)
{
        u32 tx_preset;
        u8 *cache = ppd->qsfp_info.cache;
        int cable_power_class;

        if (!((cache[QSFP_MOD_PWR_OFFS] & 0x8) &&
              (cache[QSFP_CDR_INFO_OFFS] & 0x80)))
                return;

        /* TX CDR present, bypass supported */
        cable_power_class = get_qsfp_power_class(cache[QSFP_MOD_PWR_OFFS]);

        if (cable_power_class <= QSFP_POWER_CLASS_3) {
                /* Power class <= 3, ignore config & turn TX CDR on */
                *cdr_ctrl_byte |= 0xF0;
                return;
        }

        get_platform_config_field(
                ppd->dd,
                PLATFORM_CONFIG_TX_PRESET_TABLE, tx_preset_index,
                TX_PRESET_TABLE_QSFP_TX_CDR_APPLY, &tx_preset, 4);

        if (!tx_preset) {
                dd_dev_info(
                        ppd->dd,
                        "%s: TX_CDR_APPLY is set to disabled\n",
                        __func__);
                return;
        }
        get_platform_config_field(
                ppd->dd,
                PLATFORM_CONFIG_TX_PRESET_TABLE,
                tx_preset_index,
                TX_PRESET_TABLE_QSFP_TX_CDR, &tx_preset, 4);

        /* Expand cdr setting to all 4 lanes */
        tx_preset = (tx_preset | (tx_preset << 1) |
                        (tx_preset << 2) | (tx_preset << 3));

        if (tx_preset)
                *cdr_ctrl_byte |= (tx_preset << 4);
        else
                /* Preserve current/determined RX CDR status */
                *cdr_ctrl_byte &= ((tx_preset << 4) | 0xF);
}

static void apply_cdr_settings(
                struct hfi1_pportdata *ppd, u32 rx_preset_index,
                u32 tx_preset_index)
{
        u8 *cache = ppd->qsfp_info.cache;
        u8 cdr_ctrl_byte = cache[QSFP_CDR_CTRL_BYTE_OFFS];

        apply_rx_cdr(ppd, rx_preset_index, &cdr_ctrl_byte);

        apply_tx_cdr(ppd, tx_preset_index, &cdr_ctrl_byte);

        qsfp_write(ppd, ppd->dd->hfi1_id, QSFP_CDR_CTRL_BYTE_OFFS,
                   &cdr_ctrl_byte, 1);
}

static void apply_tx_eq_auto(struct hfi1_pportdata *ppd)
{
        u8 *cache = ppd->qsfp_info.cache;
        u8 tx_eq;

        if (!(cache[QSFP_EQ_INFO_OFFS] & 0x8))
                return;
        /* Disable adaptive TX EQ if present */
        tx_eq = cache[(128 * 3) + 241];
        tx_eq &= 0xF0;
        qsfp_write(ppd, ppd->dd->hfi1_id, (256 * 3) + 241, &tx_eq, 1);
}

static void apply_tx_eq_prog(struct hfi1_pportdata *ppd, u32 tx_preset_index)
{
        u8 *cache = ppd->qsfp_info.cache;
        u32 tx_preset;
        u8 tx_eq;

        if (!(cache[QSFP_EQ_INFO_OFFS] & 0x4))
                return;

        get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_TX_PRESET_TABLE,
                tx_preset_index, TX_PRESET_TABLE_QSFP_TX_EQ_APPLY,
                &tx_preset, 4);
        if (!tx_preset) {
                dd_dev_info(
                        ppd->dd,
                        "%s: TX_EQ_APPLY is set to disabled\n",
                        __func__);
                return;
        }
        get_platform_config_field(
                        ppd->dd, PLATFORM_CONFIG_TX_PRESET_TABLE,
                        tx_preset_index, TX_PRESET_TABLE_QSFP_TX_EQ,
                        &tx_preset, 4);

        if (((cache[(128 * 3) + 224] & 0xF0) >> 4) < tx_preset) {
                dd_dev_info(
                        ppd->dd,
                        "%s: TX EQ %x unsupported\n",
                        __func__, tx_preset);

                dd_dev_info(
                        ppd->dd,
                        "%s: Applying EQ %x\n",
                        __func__, cache[608] & 0xF0);

                tx_preset = (cache[608] & 0xF0) >> 4;
        }

        tx_eq = tx_preset | (tx_preset << 4);
        qsfp_write(ppd, ppd->dd->hfi1_id, (256 * 3) + 234, &tx_eq, 1);
        qsfp_write(ppd, ppd->dd->hfi1_id, (256 * 3) + 235, &tx_eq, 1);
}

static void apply_rx_eq_emp(struct hfi1_pportdata *ppd, u32 rx_preset_index)
{
        u32 rx_preset;
        u8 rx_eq, *cache = ppd->qsfp_info.cache;

        if (!(cache[QSFP_EQ_INFO_OFFS] & 0x2))
                return;
        get_platform_config_field(
                        ppd->dd, PLATFORM_CONFIG_RX_PRESET_TABLE,
                        rx_preset_index, RX_PRESET_TABLE_QSFP_RX_EMP_APPLY,
                        &rx_preset, 4);

        if (!rx_preset) {
                dd_dev_info(
                        ppd->dd,
                        "%s: RX_EMP_APPLY is set to disabled\n",
                        __func__);
                return;
        }
        get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_RX_PRESET_TABLE,
                rx_preset_index, RX_PRESET_TABLE_QSFP_RX_EMP,
                &rx_preset, 4);

        if ((cache[(128 * 3) + 224] & 0xF) < rx_preset) {
                dd_dev_info(
                        ppd->dd,
                        "%s: Requested RX EMP %x\n",
                        __func__, rx_preset);

                dd_dev_info(
                        ppd->dd,
                        "%s: Applying supported EMP %x\n",
                        __func__, cache[608] & 0xF);

                rx_preset = cache[608] & 0xF;
        }

        rx_eq = rx_preset | (rx_preset << 4);

        qsfp_write(ppd, ppd->dd->hfi1_id, (256 * 3) + 236, &rx_eq, 1);
        qsfp_write(ppd, ppd->dd->hfi1_id, (256 * 3) + 237, &rx_eq, 1);
}

static void apply_eq_settings(struct hfi1_pportdata *ppd,
                              u32 rx_preset_index, u32 tx_preset_index)
{
        u8 *cache = ppd->qsfp_info.cache;

        /* no point going on w/o a page 3 */
        if (cache[2] & 4) {
                dd_dev_info(ppd->dd,
                            "%s: Upper page 03 not present\n",
                            __func__);
                return;
        }

        apply_tx_eq_auto(ppd);

        apply_tx_eq_prog(ppd, tx_preset_index);

        apply_rx_eq_emp(ppd, rx_preset_index);
}

static void apply_rx_amplitude_settings(
                struct hfi1_pportdata *ppd, u32 rx_preset_index,
                u32 tx_preset_index)
{
        u32 rx_preset;
        u8 rx_amp = 0, i = 0, preferred = 0, *cache = ppd->qsfp_info.cache;

        /* no point going on w/o a page 3 */
        if (cache[2] & 4) {
                dd_dev_info(ppd->dd,
                            "%s: Upper page 03 not present\n",
                            __func__);
                return;
        }
        if (!(cache[QSFP_EQ_INFO_OFFS] & 0x1)) {
                dd_dev_info(ppd->dd,
                            "%s: RX_AMP_APPLY is set to disabled\n",
                            __func__);
                return;
        }

        get_platform_config_field(ppd->dd,
                                  PLATFORM_CONFIG_RX_PRESET_TABLE,
                                  rx_preset_index,
                                  RX_PRESET_TABLE_QSFP_RX_AMP_APPLY,
                                  &rx_preset, 4);

        if (!rx_preset) {
                dd_dev_info(ppd->dd,
                            "%s: RX_AMP_APPLY is set to disabled\n",
                            __func__);
                return;
        }
        get_platform_config_field(ppd->dd,
                                  PLATFORM_CONFIG_RX_PRESET_TABLE,
                                  rx_preset_index,
                                  RX_PRESET_TABLE_QSFP_RX_AMP,
                                  &rx_preset, 4);

        dd_dev_info(ppd->dd,
                    "%s: Requested RX AMP %x\n",
                    __func__,
                    rx_preset);

        for (i = 0; i < 4; i++) {
                if (cache[(128 * 3) + 225] & (1 << i)) {
                        preferred = i;
                        if (preferred == rx_preset)
                                break;
                }
        }

        /*
         * Verify that preferred RX amplitude is not just a
         * fall through of the default
         */
        if (!preferred && !(cache[(128 * 3) + 225] & 0x1)) {
                dd_dev_info(ppd->dd, "No supported RX AMP, not applying\n");
                return;
        }

        dd_dev_info(ppd->dd,
                    "%s: Applying RX AMP %x\n", __func__, preferred);

        rx_amp = preferred | (preferred << 4);
        qsfp_write(ppd, ppd->dd->hfi1_id, (256 * 3) + 238, &rx_amp, 1);
        qsfp_write(ppd, ppd->dd->hfi1_id, (256 * 3) + 239, &rx_amp, 1);
}

#define OPA_INVALID_INDEX 0xFFF

static void apply_tx_lanes(struct hfi1_pportdata *ppd, u8 field_id,
                           u32 config_data, const char *message)
{
        u8 i;
        int ret;

        for (i = 0; i < 4; i++) {
                ret = load_8051_config(ppd->dd, field_id, i, config_data);
                if (ret != HCMD_SUCCESS) {
                        dd_dev_err(
                                ppd->dd,
                                "%s: %s for lane %u failed\n",
                                message, __func__, i);
                }
        }
}

/*
 * Return a special SerDes setting for low power AOC cables.  The power class
 * threshold and setting being used were all found by empirical testing.
 *
 * Summary of the logic:
 *
 * if (QSFP and QSFP_TYPE == AOC and QSFP_POWER_CLASS < 4)
 *     return 0xe
 * return 0; // leave at default
 */
static u8 aoc_low_power_setting(struct hfi1_pportdata *ppd)
{
        u8 *cache = ppd->qsfp_info.cache;
        int power_class;

        /* QSFP only */
        if (ppd->port_type != PORT_TYPE_QSFP)
                return 0; /* leave at default */

        /* active optical cables only */
        switch ((cache[QSFP_MOD_TECH_OFFS] & 0xF0) >> 4) {
        case 0x0 ... 0x9: /* fallthrough */
        case 0xC: /* fallthrough */
        case 0xE:
                /* active AOC */
                power_class = get_qsfp_power_class(cache[QSFP_MOD_PWR_OFFS]);
                if (power_class < QSFP_POWER_CLASS_4)
                        return 0xe;
        }
        return 0; /* leave at default */
}

static void apply_tunings(
                struct hfi1_pportdata *ppd, u32 tx_preset_index,
                u8 tuning_method, u32 total_atten, u8 limiting_active)
{
        int ret = 0;
        u32 config_data = 0, tx_preset = 0;
        u8 precur = 0, attn = 0, postcur = 0, external_device_config = 0;
        u8 *cache = ppd->qsfp_info.cache;

        /* Pass tuning method to 8051 */
        read_8051_config(ppd->dd, LINK_TUNING_PARAMETERS, GENERAL_CONFIG,
                         &config_data);
        config_data &= ~(0xff << TUNING_METHOD_SHIFT);
        config_data |= ((u32)tuning_method << TUNING_METHOD_SHIFT);
        ret = load_8051_config(ppd->dd, LINK_TUNING_PARAMETERS, GENERAL_CONFIG,
                               config_data);
        if (ret != HCMD_SUCCESS)
                dd_dev_err(ppd->dd, "%s: Failed to set tuning method\n",
                           __func__);

        /* Set same channel loss for both TX and RX */
        config_data = 0 | (total_atten << 16) | (total_atten << 24);
        apply_tx_lanes(ppd, CHANNEL_LOSS_SETTINGS, config_data,
                       "Setting channel loss");

        /* Inform 8051 of cable capabilities */
        if (ppd->qsfp_info.cache_valid) {
                external_device_config =
                        ((cache[QSFP_MOD_PWR_OFFS] & 0x4) << 3) |
                        ((cache[QSFP_MOD_PWR_OFFS] & 0x8) << 2) |
                        ((cache[QSFP_EQ_INFO_OFFS] & 0x2) << 1) |
                        (cache[QSFP_EQ_INFO_OFFS] & 0x4);
                ret = read_8051_config(ppd->dd, DC_HOST_COMM_SETTINGS,
                                       GENERAL_CONFIG, &config_data);
                /* Clear, then set the external device config field */
                config_data &= ~(u32)0xFF;
                config_data |= external_device_config;
                ret = load_8051_config(ppd->dd, DC_HOST_COMM_SETTINGS,
                                       GENERAL_CONFIG, config_data);
                if (ret != HCMD_SUCCESS)
                        dd_dev_err(ppd->dd,
                                   "%s: Failed set ext device config params\n",
                                   __func__);
        }

        if (tx_preset_index == OPA_INVALID_INDEX) {
                if (ppd->port_type == PORT_TYPE_QSFP && limiting_active)
                        dd_dev_err(ppd->dd, "%s: Invalid Tx preset index\n",
                                   __func__);
                return;
        }

        /* Following for limiting active channels only */
        get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_TX_PRESET_TABLE, tx_preset_index,
                TX_PRESET_TABLE_PRECUR, &tx_preset, 4);
        precur = tx_preset;

        get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_TX_PRESET_TABLE,
                tx_preset_index, TX_PRESET_TABLE_ATTN, &tx_preset, 4);
        attn = tx_preset;

        get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_TX_PRESET_TABLE,
                tx_preset_index, TX_PRESET_TABLE_POSTCUR, &tx_preset, 4);
        postcur = tx_preset;

        /*
         * NOTES:
         * o The aoc_low_power_setting is applied to all lanes even
         *   though only lane 0's value is examined by the firmware.
         * o A lingering low power setting after a cable swap does
         *   not occur.  On cable unplug the 8051 is reset and
         *   restarted on cable insert.  This resets all settings to
         *   their default, erasing any previous low power setting.
         */
        config_data = precur | (attn << 8) | (postcur << 16) |
                        (aoc_low_power_setting(ppd) << 24);

        apply_tx_lanes(ppd, TX_EQ_SETTINGS, config_data,
                       "Applying TX settings");
}

/* Must be holding the QSFP i2c resource */
static int tune_active_qsfp(struct hfi1_pportdata *ppd, u32 *ptr_tx_preset,
                            u32 *ptr_rx_preset, u32 *ptr_total_atten)
{
        int ret;
        u16 lss = ppd->link_speed_supported, lse = ppd->link_speed_enabled;
        u8 *cache = ppd->qsfp_info.cache;

        ppd->qsfp_info.limiting_active = 1;

        ret = set_qsfp_tx(ppd, 0);
        if (ret)
                return ret;

        ret = qual_power(ppd);
        if (ret)
                return ret;

        ret = qual_bitrate(ppd);
        if (ret)
                return ret;

        /*
         * We'll change the QSFP memory contents from here on out, thus we set a
         * flag here to remind ourselves to reset the QSFP module. This prevents
         * reuse of stale settings established in our previous pass through.
         */
        if (ppd->qsfp_info.reset_needed) {
                ret = reset_qsfp(ppd);
                if (ret)
                        return ret;
                refresh_qsfp_cache(ppd, &ppd->qsfp_info);
        } else {
                ppd->qsfp_info.reset_needed = 1;
        }

        ret = set_qsfp_high_power(ppd);
        if (ret)
                return ret;

        if (cache[QSFP_EQ_INFO_OFFS] & 0x4) {
                ret = get_platform_config_field(
                        ppd->dd,
                        PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_TX_PRESET_IDX_ACTIVE_EQ,
                        ptr_tx_preset, 4);
                if (ret) {
                        *ptr_tx_preset = OPA_INVALID_INDEX;
                        return ret;
                }
        } else {
                ret = get_platform_config_field(
                        ppd->dd,
                        PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_TX_PRESET_IDX_ACTIVE_NO_EQ,
                        ptr_tx_preset, 4);
                if (ret) {
                        *ptr_tx_preset = OPA_INVALID_INDEX;
                        return ret;
                }
        }

        ret = get_platform_config_field(
                ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                PORT_TABLE_RX_PRESET_IDX, ptr_rx_preset, 4);
        if (ret) {
                *ptr_rx_preset = OPA_INVALID_INDEX;
                return ret;
        }

        if ((lss & OPA_LINK_SPEED_25G) && (lse & OPA_LINK_SPEED_25G))
                get_platform_config_field(
                        ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_LOCAL_ATTEN_25G, ptr_total_atten, 4);
        else if ((lss & OPA_LINK_SPEED_12_5G) && (lse & OPA_LINK_SPEED_12_5G))
                get_platform_config_field(
                        ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_LOCAL_ATTEN_12G, ptr_total_atten, 4);

        apply_cdr_settings(ppd, *ptr_rx_preset, *ptr_tx_preset);

        apply_eq_settings(ppd, *ptr_rx_preset, *ptr_tx_preset);

        apply_rx_amplitude_settings(ppd, *ptr_rx_preset, *ptr_tx_preset);

        ret = set_qsfp_tx(ppd, 1);

        return ret;
}

static int tune_qsfp(struct hfi1_pportdata *ppd,
                     u32 *ptr_tx_preset, u32 *ptr_rx_preset,
                     u8 *ptr_tuning_method, u32 *ptr_total_atten)
{
        u32 cable_atten = 0, remote_atten = 0, platform_atten = 0;
        u16 lss = ppd->link_speed_supported, lse = ppd->link_speed_enabled;
        int ret = 0;
        u8 *cache = ppd->qsfp_info.cache;

        switch ((cache[QSFP_MOD_TECH_OFFS] & 0xF0) >> 4) {
        case 0xA ... 0xB:
                ret = get_platform_config_field(
                        ppd->dd,
                        PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_LOCAL_ATTEN_25G,
                        &platform_atten, 4);
                if (ret)
                        return ret;

                if ((lss & OPA_LINK_SPEED_25G) && (lse & OPA_LINK_SPEED_25G))
                        cable_atten = cache[QSFP_CU_ATTEN_12G_OFFS];
                else if ((lss & OPA_LINK_SPEED_12_5G) &&
                         (lse & OPA_LINK_SPEED_12_5G))
                        cable_atten = cache[QSFP_CU_ATTEN_7G_OFFS];

                /* Fallback to configured attenuation if cable memory is bad */
                if (cable_atten == 0 || cable_atten > 36) {
                        ret = get_platform_config_field(
                                ppd->dd,
                                PLATFORM_CONFIG_SYSTEM_TABLE, 0,
                                SYSTEM_TABLE_QSFP_ATTENUATION_DEFAULT_25G,
                                &cable_atten, 4);
                        if (ret)
                                return ret;
                }

                ret = get_platform_config_field(
                        ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_REMOTE_ATTEN_25G, &remote_atten, 4);
                if (ret)
                        return ret;

                *ptr_total_atten = platform_atten + cable_atten + remote_atten;

                *ptr_tuning_method = OPA_PASSIVE_TUNING;
                break;
        case 0x0 ... 0x9: /* fallthrough */
        case 0xC: /* fallthrough */
        case 0xE:
                ret = tune_active_qsfp(ppd, ptr_tx_preset, ptr_rx_preset,
                                       ptr_total_atten);
                if (ret)
                        return ret;

                *ptr_tuning_method = OPA_ACTIVE_TUNING;
                break;
        case 0xD: /* fallthrough */
        case 0xF:
        default:
                dd_dev_warn(ppd->dd, "%s: Unknown/unsupported cable\n",
                            __func__);
                break;
        }
        return ret;
}

/*
 * This function communicates its success or failure via ppd->driver_link_ready
 * Thus, it depends on its association with start_link(...) which checks
 * driver_link_ready before proceeding with the link negotiation and
 * initialization process.
 */
void tune_serdes(struct hfi1_pportdata *ppd)
{
        int ret = 0;
        u32 total_atten = 0;
        u32 remote_atten = 0, platform_atten = 0;
        u32 rx_preset_index, tx_preset_index;
        u8 tuning_method = 0, limiting_active = 0;
        struct hfi1_devdata *dd = ppd->dd;

        rx_preset_index = OPA_INVALID_INDEX;
        tx_preset_index = OPA_INVALID_INDEX;

        /* the link defaults to enabled */
        ppd->link_enabled = 1;
        /* the driver link ready state defaults to not ready */
        ppd->driver_link_ready = 0;
        ppd->offline_disabled_reason = HFI1_ODR_MASK(OPA_LINKDOWN_REASON_NONE);

        /* Skip the tuning for testing (loopback != none) and simulations */
        if (loopback != LOOPBACK_NONE ||
            ppd->dd->icode == ICODE_FUNCTIONAL_SIMULATOR) {
                ppd->driver_link_ready = 1;

                if (qsfp_mod_present(ppd)) {
                        ret = acquire_chip_resource(ppd->dd,
                                                    qsfp_resource(ppd->dd),
                                                    QSFP_WAIT);
                        if (ret) {
                                dd_dev_err(ppd->dd, "%s: hfi%d: cannot lock i2c chain\n",
                                           __func__, (int)ppd->dd->hfi1_id);
                                goto bail;
                        }

                        refresh_qsfp_cache(ppd, &ppd->qsfp_info);
                        release_chip_resource(ppd->dd, qsfp_resource(ppd->dd));
                }

                return;
        }

        switch (ppd->port_type) {
        case PORT_TYPE_DISCONNECTED:
                ppd->offline_disabled_reason =
                        HFI1_ODR_MASK(OPA_LINKDOWN_REASON_DISCONNECTED);
                dd_dev_warn(dd, "%s: Port disconnected, disabling port\n",
                            __func__);
                goto bail;
        case PORT_TYPE_FIXED:
                /* platform_atten, remote_atten pre-zeroed to catch error */
                get_platform_config_field(
                        ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_LOCAL_ATTEN_25G, &platform_atten, 4);

                get_platform_config_field(
                        ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                        PORT_TABLE_REMOTE_ATTEN_25G, &remote_atten, 4);

                total_atten = platform_atten + remote_atten;

                tuning_method = OPA_PASSIVE_TUNING;
                break;
        case PORT_TYPE_VARIABLE:
                if (qsfp_mod_present(ppd)) {
                        /*
                         * platform_atten, remote_atten pre-zeroed to
                         * catch error
                         */
                        get_platform_config_field(
                                ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                                PORT_TABLE_LOCAL_ATTEN_25G,
                                &platform_atten, 4);

                        get_platform_config_field(

                                ppd->dd, PLATFORM_CONFIG_PORT_TABLE, 0,
                                PORT_TABLE_REMOTE_ATTEN_25G,
                                &remote_atten, 4);

                        total_atten = platform_atten + remote_atten;

                        tuning_method = OPA_PASSIVE_TUNING;
                } else {
                        ppd->offline_disabled_reason =
                             HFI1_ODR_MASK(OPA_LINKDOWN_REASON_CHASSIS_CONFIG);
                        goto bail;
                }
                break;
        case PORT_TYPE_QSFP:
                if (qsfp_mod_present(ppd)) {
                        ret = acquire_chip_resource(ppd->dd,
                                                    qsfp_resource(ppd->dd),
                                                    QSFP_WAIT);
                        if (ret) {
                                dd_dev_err(ppd->dd, "%s: hfi%d: cannot lock i2c chain\n",
                                           __func__, (int)ppd->dd->hfi1_id);
                                goto bail;
                        }
                        refresh_qsfp_cache(ppd, &ppd->qsfp_info);

                        if (ppd->qsfp_info.cache_valid) {
                                ret = tune_qsfp(ppd,
                                                &tx_preset_index,
                                                &rx_preset_index,
                                                &tuning_method,
                                                &total_atten);

                                /*
                                 * We may have modified the QSFP memory, so
                                 * update the cache to reflect the changes
                                 */
                                refresh_qsfp_cache(ppd, &ppd->qsfp_info);
                                limiting_active =
                                                ppd->qsfp_info.limiting_active;
                        } else {
                                dd_dev_err(dd,
                                           "%s: Reading QSFP memory failed\n",
                                           __func__);
                                ret = -EINVAL; /* a fail indication */
                        }
                        release_chip_resource(ppd->dd, qsfp_resource(ppd->dd));
                        if (ret)
                                goto bail;
                } else {
                        ppd->offline_disabled_reason =
                           HFI1_ODR_MASK(
                                OPA_LINKDOWN_REASON_LOCAL_MEDIA_NOT_INSTALLED);
                        goto bail;
                }
                break;
        default:
                dd_dev_warn(ppd->dd, "%s: Unknown port type\n", __func__);
                ppd->port_type = PORT_TYPE_UNKNOWN;
                tuning_method = OPA_UNKNOWN_TUNING;
                total_atten = 0;
                limiting_active = 0;
                tx_preset_index = OPA_INVALID_INDEX;
                break;
        }

        if (ppd->offline_disabled_reason ==
                        HFI1_ODR_MASK(OPA_LINKDOWN_REASON_NONE))
                apply_tunings(ppd, tx_preset_index, tuning_method,
                              total_atten, limiting_active);

        if (!ret)
                ppd->driver_link_ready = 1;

        return;
bail:
        ppd->driver_link_ready = 0;
}