/*
 * Copyright(c) 2015 - 2019 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/pci.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/vmalloc.h>
#include <linux/aer.h>
#include <linux/module.h>

#include "hfi.h"
#include "chip_registers.h"
#include "aspm.h"

/*
 * This file contains PCIe utility routines.
 */

/*
 * Do all the common PCIe setup and initialization.
 */
int hfi1_pcie_init(struct hfi1_devdata *dd)
{
        int ret;
        struct pci_dev *pdev = dd->pcidev;

        ret = pci_enable_device(pdev);
        if (ret) {
                /*
                 * This can happen (in theory) iff:
                 * We did a chip reset, and then failed to reprogram the
                 * BAR, or the chip reset due to an internal error.  We then
                 * unloaded the driver and reloaded it.
                 *
                 * Both reset cases set the BAR back to initial state.  For
                 * the latter case, the AER sticky error bit at offset 0x718
                 * should be set, but the Linux kernel doesn't yet know
                 * about that, it appears.  If the original BAR was retained
                 * in the kernel data structures, this may be OK.
                 */
                dd_dev_err(dd, "pci enable failed: error %d\n", -ret);
                return ret;
        }

        ret = pci_request_regions(pdev, DRIVER_NAME);
        if (ret) {
                dd_dev_err(dd, "pci_request_regions fails: err %d\n", -ret);
                goto bail;
        }

        ret = pci_set_dma_mask(pdev, DMA_BIT_MASK(64));
        if (ret) {
                /*
                 * If the 64 bit setup fails, try 32 bit.  Some systems
                 * do not setup 64 bit maps on systems with 2GB or less
                 * memory installed.
                 */
                ret = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
                if (ret) {
                        dd_dev_err(dd, "Unable to set DMA mask: %d\n", ret);
                        goto bail;
                }
                ret = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32));
        } else {
                ret = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64));
        }
        if (ret) {
                dd_dev_err(dd, "Unable to set DMA consistent mask: %d\n", ret);
                goto bail;
        }

        pci_set_master(pdev);
        (void)pci_enable_pcie_error_reporting(pdev);
        return 0;

bail:
        hfi1_pcie_cleanup(pdev);
        return ret;
}

/*
 * Clean what was done in hfi1_pcie_init()
 */
void hfi1_pcie_cleanup(struct pci_dev *pdev)
{
        pci_disable_device(pdev);
        /*
         * Release regions should be called after the disable. OK to
         * call if request regions has not been called or failed.
         */
        pci_release_regions(pdev);
}

/*
 * Do remaining PCIe setup, once dd is allocated, and save away
 * fields required to re-initialize after a chip reset, or for
 * various other purposes
 */
int hfi1_pcie_ddinit(struct hfi1_devdata *dd, struct pci_dev *pdev)
{
        unsigned long len;
        resource_size_t addr;
        int ret = 0;
        u32 rcv_array_count;

        addr = pci_resource_start(pdev, 0);
        len = pci_resource_len(pdev, 0);

        /*
         * The TXE PIO buffers are at the tail end of the chip space.
         * Cut them off and map them separately.
         */

        /* sanity check vs expectations */
        if (len != TXE_PIO_SEND + TXE_PIO_SIZE) {
                dd_dev_err(dd, "chip PIO range does not match\n");
                return -EINVAL;
        }

        dd->kregbase1 = ioremap(addr, RCV_ARRAY);
        if (!dd->kregbase1) {
                dd_dev_err(dd, "UC mapping of kregbase1 failed\n");
                return -ENOMEM;
        }
        dd_dev_info(dd, "UC base1: %p for %x\n", dd->kregbase1, RCV_ARRAY);

        /* verify that reads actually work, save revision for reset check */
        dd->revision = readq(dd->kregbase1 + CCE_REVISION);
        if (dd->revision == ~(u64)0) {
                dd_dev_err(dd, "Cannot read chip CSRs\n");
                goto nomem;
        }

        rcv_array_count = readq(dd->kregbase1 + RCV_ARRAY_CNT);
        dd_dev_info(dd, "RcvArray count: %u\n", rcv_array_count);
        dd->base2_start  = RCV_ARRAY + rcv_array_count * 8;

        dd->kregbase2 = ioremap(
                addr + dd->base2_start,
                TXE_PIO_SEND - dd->base2_start);
        if (!dd->kregbase2) {
                dd_dev_err(dd, "UC mapping of kregbase2 failed\n");
                goto nomem;
        }
        dd_dev_info(dd, "UC base2: %p for %x\n", dd->kregbase2,
                    TXE_PIO_SEND - dd->base2_start);

        dd->piobase = ioremap_wc(addr + TXE_PIO_SEND, TXE_PIO_SIZE);
        if (!dd->piobase) {
                dd_dev_err(dd, "WC mapping of send buffers failed\n");
                goto nomem;
        }
        dd_dev_info(dd, "WC piobase: %p for %x\n", dd->piobase, TXE_PIO_SIZE);

        dd->physaddr = addr;        /* used for io_remap, etc. */

        /*
         * Map the chip's RcvArray as write-combining to allow us
         * to write an entire cacheline worth of entries in one shot.
         */
        dd->rcvarray_wc = ioremap_wc(addr + RCV_ARRAY,
                                     rcv_array_count * 8);
        if (!dd->rcvarray_wc) {
                dd_dev_err(dd, "WC mapping of receive array failed\n");
                goto nomem;
        }
        dd_dev_info(dd, "WC RcvArray: %p for %x\n",
                    dd->rcvarray_wc, rcv_array_count * 8);

        dd->flags |= HFI1_PRESENT;      /* chip.c CSR routines now work */
        return 0;
nomem:
        ret = -ENOMEM;
        hfi1_pcie_ddcleanup(dd);
        return ret;
}

/*
 * Do PCIe cleanup related to dd, after chip-specific cleanup, etc.  Just prior
 * to releasing the dd memory.
 * Void because all of the core pcie cleanup functions are void.
 */
void hfi1_pcie_ddcleanup(struct hfi1_devdata *dd)
{
        dd->flags &= ~HFI1_PRESENT;
        if (dd->kregbase1)
                iounmap(dd->kregbase1);
        dd->kregbase1 = NULL;
        if (dd->kregbase2)
                iounmap(dd->kregbase2);
        dd->kregbase2 = NULL;
        if (dd->rcvarray_wc)
                iounmap(dd->rcvarray_wc);
        dd->rcvarray_wc = NULL;
        if (dd->piobase)
                iounmap(dd->piobase);
        dd->piobase = NULL;
}

/* return the PCIe link speed from the given link status */
static u32 extract_speed(u16 linkstat)
{
        u32 speed;

        switch (linkstat & PCI_EXP_LNKSTA_CLS) {
        default: /* not defined, assume Gen1 */
        case PCI_EXP_LNKSTA_CLS_2_5GB:
                speed = 2500; /* Gen 1, 2.5GHz */
                break;
        case PCI_EXP_LNKSTA_CLS_5_0GB:
                speed = 5000; /* Gen 2, 5GHz */
                break;
        case PCI_EXP_LNKSTA_CLS_8_0GB:
                speed = 8000; /* Gen 3, 8GHz */
                break;
        }
        return speed;
}

/* return the PCIe link speed from the given link status */
static u32 extract_width(u16 linkstat)
{
        return (linkstat & PCI_EXP_LNKSTA_NLW) >> PCI_EXP_LNKSTA_NLW_SHIFT;
}

/* read the link status and set dd->{lbus_width,lbus_speed,lbus_info} */
static void update_lbus_info(struct hfi1_devdata *dd)
{
        u16 linkstat;
        int ret;

        ret = pcie_capability_read_word(dd->pcidev, PCI_EXP_LNKSTA, &linkstat);
        if (ret) {
                dd_dev_err(dd, "Unable to read from PCI config\n");
                return;
        }

        dd->lbus_width = extract_width(linkstat);
        dd->lbus_speed = extract_speed(linkstat);
        snprintf(dd->lbus_info, sizeof(dd->lbus_info),
                 "PCIe,%uMHz,x%u", dd->lbus_speed, dd->lbus_width);
}

/*
 * Read in the current PCIe link width and speed.  Find if the link is
 * Gen3 capable.
 */
int pcie_speeds(struct hfi1_devdata *dd)
{
        u32 linkcap;
        struct pci_dev *parent = dd->pcidev->bus->self;
        int ret;

        if (!pci_is_pcie(dd->pcidev)) {
                dd_dev_err(dd, "Can't find PCI Express capability!\n");
                return -EINVAL;
        }

        /* find if our max speed is Gen3 and parent supports Gen3 speeds */
        dd->link_gen3_capable = 1;

        ret = pcie_capability_read_dword(dd->pcidev, PCI_EXP_LNKCAP, &linkcap);
        if (ret) {
                dd_dev_err(dd, "Unable to read from PCI config\n");
                return pcibios_err_to_errno(ret);
        }

        if ((linkcap & PCI_EXP_LNKCAP_SLS) != PCI_EXP_LNKCAP_SLS_8_0GB) {
                dd_dev_info(dd,
                            "This HFI is not Gen3 capable, max speed 0x%x, need 0x3\n",
                            linkcap & PCI_EXP_LNKCAP_SLS);
                dd->link_gen3_capable = 0;
        }

        /*
         * bus->max_bus_speed is set from the bridge's linkcap Max Link Speed
         */
        if (parent &&
            (dd->pcidev->bus->max_bus_speed == PCIE_SPEED_2_5GT ||
             dd->pcidev->bus->max_bus_speed == PCIE_SPEED_5_0GT)) {
                dd_dev_info(dd, "Parent PCIe bridge does not support Gen3\n");
                dd->link_gen3_capable = 0;
        }

        /* obtain the link width and current speed */
        update_lbus_info(dd);

        dd_dev_info(dd, "%s\n", dd->lbus_info);

        return 0;
}

/**
 * Restore command and BARs after a reset has wiped them out
 *
 * Returns 0 on success, otherwise a negative error value
 */
int restore_pci_variables(struct hfi1_devdata *dd)
{
        int ret;

        ret = pci_write_config_word(dd->pcidev, PCI_COMMAND, dd->pci_command);
        if (ret)
                goto error;

        ret = pci_write_config_dword(dd->pcidev, PCI_BASE_ADDRESS_0,
                                     dd->pcibar0);
        if (ret)
                goto error;

        ret = pci_write_config_dword(dd->pcidev, PCI_BASE_ADDRESS_1,
                                     dd->pcibar1);
        if (ret)
                goto error;

        ret = pci_write_config_dword(dd->pcidev, PCI_ROM_ADDRESS, dd->pci_rom);
        if (ret)
                goto error;

        ret = pcie_capability_write_word(dd->pcidev, PCI_EXP_DEVCTL,
                                         dd->pcie_devctl);
        if (ret)
                goto error;

        ret = pcie_capability_write_word(dd->pcidev, PCI_EXP_LNKCTL,
                                         dd->pcie_lnkctl);
        if (ret)
                goto error;

        ret = pcie_capability_write_word(dd->pcidev, PCI_EXP_DEVCTL2,
                                         dd->pcie_devctl2);
        if (ret)
                goto error;

        ret = pci_write_config_dword(dd->pcidev, PCI_CFG_MSIX0, dd->pci_msix0);
        if (ret)
                goto error;

        if (pci_find_ext_capability(dd->pcidev, PCI_EXT_CAP_ID_TPH)) {
                ret = pci_write_config_dword(dd->pcidev, PCIE_CFG_TPH2,
                                             dd->pci_tph2);
                if (ret)
                        goto error;
        }
        return 0;

error:
        dd_dev_err(dd, "Unable to write to PCI config\n");
        return pcibios_err_to_errno(ret);
}

/**
 * Save BARs and command to rewrite after device reset
 *
 * Returns 0 on success, otherwise a negative error value
 */
int save_pci_variables(struct hfi1_devdata *dd)
{
        int ret;

        ret = pci_read_config_dword(dd->pcidev, PCI_BASE_ADDRESS_0,
                                    &dd->pcibar0);
        if (ret)
                goto error;

        ret = pci_read_config_dword(dd->pcidev, PCI_BASE_ADDRESS_1,
                                    &dd->pcibar1);
        if (ret)
                goto error;

        ret = pci_read_config_dword(dd->pcidev, PCI_ROM_ADDRESS, &dd->pci_rom);
        if (ret)
                goto error;

        ret = pci_read_config_word(dd->pcidev, PCI_COMMAND, &dd->pci_command);
        if (ret)
                goto error;

        ret = pcie_capability_read_word(dd->pcidev, PCI_EXP_DEVCTL,
                                        &dd->pcie_devctl);
        if (ret)
                goto error;

        ret = pcie_capability_read_word(dd->pcidev, PCI_EXP_LNKCTL,
                                        &dd->pcie_lnkctl);
        if (ret)
                goto error;

        ret = pcie_capability_read_word(dd->pcidev, PCI_EXP_DEVCTL2,
                                        &dd->pcie_devctl2);
        if (ret)
                goto error;

        ret = pci_read_config_dword(dd->pcidev, PCI_CFG_MSIX0, &dd->pci_msix0);
        if (ret)
                goto error;

        if (pci_find_ext_capability(dd->pcidev, PCI_EXT_CAP_ID_TPH)) {
                ret = pci_read_config_dword(dd->pcidev, PCIE_CFG_TPH2,
                                            &dd->pci_tph2);
                if (ret)
                        goto error;
        }
        return 0;

error:
        dd_dev_err(dd, "Unable to read from PCI config\n");
        return pcibios_err_to_errno(ret);
}

/*
 * BIOS may not set PCIe bus-utilization parameters for best performance.
 * Check and optionally adjust them to maximize our throughput.
 */
static int hfi1_pcie_caps;
module_param_named(pcie_caps, hfi1_pcie_caps, int, 0444);
MODULE_PARM_DESC(pcie_caps, "Max PCIe tuning: Payload (0..3), ReadReq (4..7)");

/**
 * tune_pcie_caps() - Code to adjust PCIe capabilities.
 * @dd: Valid device data structure
 *
 */
void tune_pcie_caps(struct hfi1_devdata *dd)
{
        struct pci_dev *parent;
        u16 rc_mpss, rc_mps, ep_mpss, ep_mps;
        u16 rc_mrrs, ep_mrrs, max_mrrs, ectl;
        int ret;

        /*
         * Turn on extended tags in DevCtl in case the BIOS has turned it off
         * to improve WFR SDMA bandwidth
         */
        ret = pcie_capability_read_word(dd->pcidev, PCI_EXP_DEVCTL, &ectl);
        if ((!ret) && !(ectl & PCI_EXP_DEVCTL_EXT_TAG)) {
                dd_dev_info(dd, "Enabling PCIe extended tags\n");
                ectl |= PCI_EXP_DEVCTL_EXT_TAG;
                ret = pcie_capability_write_word(dd->pcidev,
                                                 PCI_EXP_DEVCTL, ectl);
                if (ret)
                        dd_dev_info(dd, "Unable to write to PCI config\n");
        }
        /* Find out supported and configured values for parent (root) */
        parent = dd->pcidev->bus->self;
        /*
         * The driver cannot perform the tuning if it does not have
         * access to the upstream component.
         */
        if (!parent) {
                dd_dev_info(dd, "Parent not found\n");
                return;
        }
        if (!pci_is_root_bus(parent->bus)) {
                dd_dev_info(dd, "Parent not root\n");
                return;
        }
        if (!pci_is_pcie(parent)) {
                dd_dev_info(dd, "Parent is not PCI Express capable\n");
                return;
        }
        if (!pci_is_pcie(dd->pcidev)) {
                dd_dev_info(dd, "PCI device is not PCI Express capable\n");
                return;
        }
        rc_mpss = parent->pcie_mpss;
        rc_mps = ffs(pcie_get_mps(parent)) - 8;
        /* Find out supported and configured values for endpoint (us) */
        ep_mpss = dd->pcidev->pcie_mpss;
        ep_mps = ffs(pcie_get_mps(dd->pcidev)) - 8;

        /* Find max payload supported by root, endpoint */
        if (rc_mpss > ep_mpss)
                rc_mpss = ep_mpss;

        /* If Supported greater than limit in module param, limit it */
        if (rc_mpss > (hfi1_pcie_caps & 7))
                rc_mpss = hfi1_pcie_caps & 7;
        /* If less than (allowed, supported), bump root payload */
        if (rc_mpss > rc_mps) {
                rc_mps = rc_mpss;
                pcie_set_mps(parent, 128 << rc_mps);
        }
        /* If less than (allowed, supported), bump endpoint payload */
        if (rc_mpss > ep_mps) {
                ep_mps = rc_mpss;
                pcie_set_mps(dd->pcidev, 128 << ep_mps);
        }

        /*
         * Now the Read Request size.
         * No field for max supported, but PCIe spec limits it to 4096,
         * which is code '5' (log2(4096) - 7)
         */
        max_mrrs = 5;
        if (max_mrrs > ((hfi1_pcie_caps >> 4) & 7))
                max_mrrs = (hfi1_pcie_caps >> 4) & 7;

        max_mrrs = 128 << max_mrrs;
        rc_mrrs = pcie_get_readrq(parent);
        ep_mrrs = pcie_get_readrq(dd->pcidev);

        if (max_mrrs > rc_mrrs) {
                rc_mrrs = max_mrrs;
                pcie_set_readrq(parent, rc_mrrs);
        }
        if (max_mrrs > ep_mrrs) {
                ep_mrrs = max_mrrs;
                pcie_set_readrq(dd->pcidev, ep_mrrs);
        }
}

/* End of PCIe capability tuning */

/*
 * From here through hfi1_pci_err_handler definition is invoked via
 * PCI error infrastructure, registered via pci
 */
static pci_ers_result_t
pci_error_detected(struct pci_dev *pdev, pci_channel_state_t state)
{
        struct hfi1_devdata *dd = pci_get_drvdata(pdev);
        pci_ers_result_t ret = PCI_ERS_RESULT_RECOVERED;

        switch (state) {
        case pci_channel_io_normal:
                dd_dev_info(dd, "State Normal, ignoring\n");
                break;

        case pci_channel_io_frozen:
                dd_dev_info(dd, "State Frozen, requesting reset\n");
                pci_disable_device(pdev);
                ret = PCI_ERS_RESULT_NEED_RESET;
                break;

        case pci_channel_io_perm_failure:
                if (dd) {
                        dd_dev_info(dd, "State Permanent Failure, disabling\n");
                        /* no more register accesses! */
                        dd->flags &= ~HFI1_PRESENT;
                        hfi1_disable_after_error(dd);
                }
                 /* else early, or other problem */
                ret =  PCI_ERS_RESULT_DISCONNECT;
                break;

        default: /* shouldn't happen */
                dd_dev_info(dd, "HFI1 PCI errors detected (state %d)\n",
                            state);
                break;
        }
        return ret;
}

static pci_ers_result_t
pci_mmio_enabled(struct pci_dev *pdev)
{
        u64 words = 0U;
        struct hfi1_devdata *dd = pci_get_drvdata(pdev);
        pci_ers_result_t ret = PCI_ERS_RESULT_RECOVERED;

        if (dd && dd->pport) {
                words = read_port_cntr(dd->pport, C_RX_WORDS, CNTR_INVALID_VL);
                if (words == ~0ULL)
                        ret = PCI_ERS_RESULT_NEED_RESET;
                dd_dev_info(dd,
                            "HFI1 mmio_enabled function called, read wordscntr %llx, returning %d\n",
                            words, ret);
        }
        return  ret;
}

static pci_ers_result_t
pci_slot_reset(struct pci_dev *pdev)
{
        struct hfi1_devdata *dd = pci_get_drvdata(pdev);

        dd_dev_info(dd, "HFI1 slot_reset function called, ignored\n");
        return PCI_ERS_RESULT_CAN_RECOVER;
}

static void
pci_resume(struct pci_dev *pdev)
{
        struct hfi1_devdata *dd = pci_get_drvdata(pdev);

        dd_dev_info(dd, "HFI1 resume function called\n");
        /*
         * Running jobs will fail, since it's asynchronous
         * unlike sysfs-requested reset.   Better than
         * doing nothing.
         */
        hfi1_init(dd, 1); /* same as re-init after reset */
}

const struct pci_error_handlers hfi1_pci_err_handler = {
        .error_detected = pci_error_detected,
        .mmio_enabled = pci_mmio_enabled,
        .slot_reset = pci_slot_reset,
        .resume = pci_resume,
};

/*============================================================================*/
/* PCIe Gen3 support */

/*
 * This code is separated out because it is expected to be removed in the
 * final shipping product.  If not, then it will be revisited and items
 * will be moved to more standard locations.
 */

/* ASIC_PCI_SD_HOST_STATUS.FW_DNLD_STS field values */
#define DL_STATUS_HFI0 0x1      /* hfi0 firmware download complete */
#define DL_STATUS_HFI1 0x2      /* hfi1 firmware download complete */
#define DL_STATUS_BOTH 0x3      /* hfi0 and hfi1 firmware download complete */

/* ASIC_PCI_SD_HOST_STATUS.FW_DNLD_ERR field values */
#define DL_ERR_NONE             0x0     /* no error */
#define DL_ERR_SWAP_PARITY      0x1     /* parity error in SerDes interrupt */
                                        /*   or response data */
#define DL_ERR_DISABLED 0x2     /* hfi disabled */
#define DL_ERR_SECURITY 0x3     /* security check failed */
#define DL_ERR_SBUS             0x4     /* SBus status error */
#define DL_ERR_XFR_PARITY       0x5     /* parity error during ROM transfer*/

/* gasket block secondary bus reset delay */
#define SBR_DELAY_US 200000     /* 200ms */

static uint pcie_target = 3;
module_param(pcie_target, uint, S_IRUGO);
MODULE_PARM_DESC(pcie_target, "PCIe target speed (0 skip, 1-3 Gen1-3)");

static uint pcie_force;
module_param(pcie_force, uint, S_IRUGO);
MODULE_PARM_DESC(pcie_force, "Force driver to do a PCIe firmware download even if already at target speed");

static uint pcie_retry = 5;
module_param(pcie_retry, uint, S_IRUGO);
MODULE_PARM_DESC(pcie_retry, "Driver will try this many times to reach requested speed");

#define UNSET_PSET 255
#define DEFAULT_DISCRETE_PSET 2 /* discrete HFI */
#define DEFAULT_MCP_PSET 6      /* MCP HFI */
static uint pcie_pset = UNSET_PSET;
module_param(pcie_pset, uint, S_IRUGO);
MODULE_PARM_DESC(pcie_pset, "PCIe Eq Pset value to use, range is 0-10");

static uint pcie_ctle = 3; /* discrete on, integrated on */
module_param(pcie_ctle, uint, S_IRUGO);
MODULE_PARM_DESC(pcie_ctle, "PCIe static CTLE mode, bit 0 - discrete on/off, bit 1 - integrated on/off");

/* equalization columns */
#define PREC 0
#define ATTN 1
#define POST 2

/* discrete silicon preliminary equalization values */
static const u8 discrete_preliminary_eq[11][3] = {
        /* prec   attn   post */
        {  0x00,  0x00,  0x12 },        /* p0 */
        {  0x00,  0x00,  0x0c },        /* p1 */
        {  0x00,  0x00,  0x0f },        /* p2 */
        {  0x00,  0x00,  0x09 },        /* p3 */
        {  0x00,  0x00,  0x00 },        /* p4 */
        {  0x06,  0x00,  0x00 },        /* p5 */
        {  0x09,  0x00,  0x00 },        /* p6 */
        {  0x06,  0x00,  0x0f },        /* p7 */
        {  0x09,  0x00,  0x09 },        /* p8 */
        {  0x0c,  0x00,  0x00 },        /* p9 */
        {  0x00,  0x00,  0x18 },        /* p10 */
};

/* integrated silicon preliminary equalization values */
static const u8 integrated_preliminary_eq[11][3] = {
        /* prec   attn   post */
        {  0x00,  0x1e,  0x07 },        /* p0 */
        {  0x00,  0x1e,  0x05 },        /* p1 */
        {  0x00,  0x1e,  0x06 },        /* p2 */
        {  0x00,  0x1e,  0x04 },        /* p3 */
        {  0x00,  0x1e,  0x00 },        /* p4 */
        {  0x03,  0x1e,  0x00 },        /* p5 */
        {  0x04,  0x1e,  0x00 },        /* p6 */
        {  0x03,  0x1e,  0x06 },        /* p7 */
        {  0x03,  0x1e,  0x04 },        /* p8 */
        {  0x05,  0x1e,  0x00 },        /* p9 */
        {  0x00,  0x1e,  0x0a },        /* p10 */
};

static const u8 discrete_ctle_tunings[11][4] = {
        /* DC     LF     HF     BW */
        {  0x48,  0x0b,  0x04,  0x04 }, /* p0 */
        {  0x60,  0x05,  0x0f,  0x0a }, /* p1 */
        {  0x50,  0x09,  0x06,  0x06 }, /* p2 */
        {  0x68,  0x05,  0x0f,  0x0a }, /* p3 */
        {  0x80,  0x05,  0x0f,  0x0a }, /* p4 */
        {  0x70,  0x05,  0x0f,  0x0a }, /* p5 */
        {  0x68,  0x05,  0x0f,  0x0a }, /* p6 */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p7 */
        {  0x48,  0x09,  0x06,  0x06 }, /* p8 */
        {  0x60,  0x05,  0x0f,  0x0a }, /* p9 */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p10 */
};

static const u8 integrated_ctle_tunings[11][4] = {
        /* DC     LF     HF     BW */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p0 */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p1 */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p2 */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p3 */
        {  0x58,  0x0a,  0x05,  0x05 }, /* p4 */
        {  0x48,  0x0a,  0x05,  0x05 }, /* p5 */
        {  0x40,  0x0a,  0x05,  0x05 }, /* p6 */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p7 */
        {  0x38,  0x0f,  0x00,  0x00 }, /* p8 */
        {  0x38,  0x09,  0x06,  0x06 }, /* p9 */
        {  0x38,  0x0e,  0x01,  0x01 }, /* p10 */
};

/* helper to format the value to write to hardware */
#define eq_value(pre, curr, post) \
        ((((u32)(pre)) << \
                        PCIE_CFG_REG_PL102_GEN3_EQ_PRE_CURSOR_PSET_SHIFT) \
        | (((u32)(curr)) << PCIE_CFG_REG_PL102_GEN3_EQ_CURSOR_PSET_SHIFT) \
        | (((u32)(post)) << \
                PCIE_CFG_REG_PL102_GEN3_EQ_POST_CURSOR_PSET_SHIFT))

/*
 * Load the given EQ preset table into the PCIe hardware.
 */
static int load_eq_table(struct hfi1_devdata *dd, const u8 eq[11][3], u8 fs,
                         u8 div)
{
        struct pci_dev *pdev = dd->pcidev;
        u32 hit_error = 0;
        u32 violation;
        u32 i;
        u8 c_minus1, c0, c_plus1;
        int ret;

        for (i = 0; i < 11; i++) {
                /* set index */
                pci_write_config_dword(pdev, PCIE_CFG_REG_PL103, i);
                /* write the value */
                c_minus1 = eq[i][PREC] / div;
                c0 = fs - (eq[i][PREC] / div) - (eq[i][POST] / div);
                c_plus1 = eq[i][POST] / div;
                pci_write_config_dword(pdev, PCIE_CFG_REG_PL102,
                                       eq_value(c_minus1, c0, c_plus1));
                /* check if these coefficients violate EQ rules */
                ret = pci_read_config_dword(dd->pcidev,
                                            PCIE_CFG_REG_PL105, &violation);
                if (ret) {
                        dd_dev_err(dd, "Unable to read from PCI config\n");
                        hit_error = 1;
                        break;
                }

                if (violation
                    & PCIE_CFG_REG_PL105_GEN3_EQ_VIOLATE_COEF_RULES_SMASK){
                        if (hit_error == 0) {
                                dd_dev_err(dd,
                                           "Gen3 EQ Table Coefficient rule violations\n");
                                dd_dev_err(dd, "         prec   attn   post\n");
                        }
                        dd_dev_err(dd, "   p%02d:   %02x     %02x     %02x\n",
                                   i, (u32)eq[i][0], (u32)eq[i][1],
                                   (u32)eq[i][2]);
                        dd_dev_err(dd, "            %02x     %02x     %02x\n",
                                   (u32)c_minus1, (u32)c0, (u32)c_plus1);
                        hit_error = 1;
                }
        }
        if (hit_error)
                return -EINVAL;
        return 0;
}

/*
 * Steps to be done after the PCIe firmware is downloaded and
 * before the SBR for the Pcie Gen3.
 * The SBus resource is already being held.
 */
static void pcie_post_steps(struct hfi1_devdata *dd)
{
        int i;

        set_sbus_fast_mode(dd);
        /*
         * Write to the PCIe PCSes to set the G3_LOCKED_NEXT bits to 1.
         * This avoids a spurious framing error that can otherwise be
         * generated by the MAC layer.
         *
         * Use individual addresses since no broadcast is set up.
         */
        for (i = 0; i < NUM_PCIE_SERDES; i++) {
                sbus_request(dd, pcie_pcs_addrs[dd->hfi1_id][i],
                             0x03, WRITE_SBUS_RECEIVER, 0x00022132);
        }

        clear_sbus_fast_mode(dd);
}

/*
 * Trigger a secondary bus reset (SBR) on ourselves using our parent.
 *
 * Based on pci_parent_bus_reset() which is not exported by the
 * kernel core.
 */
static int trigger_sbr(struct hfi1_devdata *dd)
{
        struct pci_dev *dev = dd->pcidev;
        struct pci_dev *pdev;

        /* need a parent */
        if (!dev->bus->self) {
                dd_dev_err(dd, "%s: no parent device\n", __func__);
                return -ENOTTY;
        }

        /* should not be anyone else on the bus */
        list_for_each_entry(pdev, &dev->bus->devices, bus_list)
                if (pdev != dev) {
                        dd_dev_err(dd,
                                   "%s: another device is on the same bus\n",
                                   __func__);
                        return -ENOTTY;
                }

        /*
         * This is an end around to do an SBR during probe time. A new API needs
         * to be implemented to have cleaner interface but this fixes the
         * current brokenness
         */
        return pci_bridge_secondary_bus_reset(dev->bus->self);
}

/*
 * Write the given gasket interrupt register.
 */
static void write_gasket_interrupt(struct hfi1_devdata *dd, int index,
                                   u16 code, u16 data)
{
        write_csr(dd, ASIC_PCIE_SD_INTRPT_LIST + (index * 8),
                  (((u64)code << ASIC_PCIE_SD_INTRPT_LIST_INTRPT_CODE_SHIFT) |
                   ((u64)data << ASIC_PCIE_SD_INTRPT_LIST_INTRPT_DATA_SHIFT)));
}

/*
 * Tell the gasket logic how to react to the reset.
 */
static void arm_gasket_logic(struct hfi1_devdata *dd)
{
        u64 reg;

        reg = (((u64)1 << dd->hfi1_id) <<
               ASIC_PCIE_SD_HOST_CMD_INTRPT_CMD_SHIFT) |
              ((u64)pcie_serdes_broadcast[dd->hfi1_id] <<
               ASIC_PCIE_SD_HOST_CMD_SBUS_RCVR_ADDR_SHIFT |
               ASIC_PCIE_SD_HOST_CMD_SBR_MODE_SMASK |
               ((u64)SBR_DELAY_US & ASIC_PCIE_SD_HOST_CMD_TIMER_MASK) <<
               ASIC_PCIE_SD_HOST_CMD_TIMER_SHIFT);
        write_csr(dd, ASIC_PCIE_SD_HOST_CMD, reg);
        /* read back to push the write */
        read_csr(dd, ASIC_PCIE_SD_HOST_CMD);
}

/*
 * CCE_PCIE_CTRL long name helpers
 * We redefine these shorter macros to use in the code while leaving
 * chip_registers.h to be autogenerated from the hardware spec.
 */
#define LANE_BUNDLE_MASK              CCE_PCIE_CTRL_PCIE_LANE_BUNDLE_MASK
#define LANE_BUNDLE_SHIFT             CCE_PCIE_CTRL_PCIE_LANE_BUNDLE_SHIFT
#define LANE_DELAY_MASK               CCE_PCIE_CTRL_PCIE_LANE_DELAY_MASK
#define LANE_DELAY_SHIFT              CCE_PCIE_CTRL_PCIE_LANE_DELAY_SHIFT
#define MARGIN_OVERWRITE_ENABLE_SHIFT CCE_PCIE_CTRL_XMT_MARGIN_OVERWRITE_ENABLE_SHIFT
#define MARGIN_SHIFT                  CCE_PCIE_CTRL_XMT_MARGIN_SHIFT
#define MARGIN_G1_G2_OVERWRITE_MASK   CCE_PCIE_CTRL_XMT_MARGIN_GEN1_GEN2_OVERWRITE_ENABLE_MASK
#define MARGIN_G1_G2_OVERWRITE_SHIFT  CCE_PCIE_CTRL_XMT_MARGIN_GEN1_GEN2_OVERWRITE_ENABLE_SHIFT
#define MARGIN_GEN1_GEN2_MASK         CCE_PCIE_CTRL_XMT_MARGIN_GEN1_GEN2_MASK
#define MARGIN_GEN1_GEN2_SHIFT        CCE_PCIE_CTRL_XMT_MARGIN_GEN1_GEN2_SHIFT

 /*
  * Write xmt_margin for full-swing (WFR-B) or half-swing (WFR-C).
  */
static void write_xmt_margin(struct hfi1_devdata *dd, const char *fname)
{
        u64 pcie_ctrl;
        u64 xmt_margin;
        u64 xmt_margin_oe;
        u64 lane_delay;
        u64 lane_bundle;

        pcie_ctrl = read_csr(dd, CCE_PCIE_CTRL);

        /*
         * For Discrete, use full-swing.
         *  - PCIe TX defaults to full-swing.
         *    Leave this register as default.
         * For Integrated, use half-swing
         *  - Copy xmt_margin and xmt_margin_oe
         *    from Gen1/Gen2 to Gen3.
         */
        if (dd->pcidev->device == PCI_DEVICE_ID_INTEL1) { /* integrated */
                /* extract initial fields */
                xmt_margin = (pcie_ctrl >> MARGIN_GEN1_GEN2_SHIFT)
                              & MARGIN_GEN1_GEN2_MASK;
                xmt_margin_oe = (pcie_ctrl >> MARGIN_G1_G2_OVERWRITE_SHIFT)
                                 & MARGIN_G1_G2_OVERWRITE_MASK;
                lane_delay = (pcie_ctrl >> LANE_DELAY_SHIFT) & LANE_DELAY_MASK;
                lane_bundle = (pcie_ctrl >> LANE_BUNDLE_SHIFT)
                               & LANE_BUNDLE_MASK;

                /*
                 * For A0, EFUSE values are not set.  Override with the
                 * correct values.
                 */
                if (is_ax(dd)) {
                        /*
                         * xmt_margin and OverwiteEnabel should be the
                         * same for Gen1/Gen2 and Gen3
                         */
                        xmt_margin = 0x5;
                        xmt_margin_oe = 0x1;
                        lane_delay = 0xF; /* Delay 240ns. */
                        lane_bundle = 0x0; /* Set to 1 lane. */
                }

                /* overwrite existing values */
                pcie_ctrl = (xmt_margin << MARGIN_GEN1_GEN2_SHIFT)
                        | (xmt_margin_oe << MARGIN_G1_G2_OVERWRITE_SHIFT)
                        | (xmt_margin << MARGIN_SHIFT)
                        | (xmt_margin_oe << MARGIN_OVERWRITE_ENABLE_SHIFT)
                        | (lane_delay << LANE_DELAY_SHIFT)
                        | (lane_bundle << LANE_BUNDLE_SHIFT);

                write_csr(dd, CCE_PCIE_CTRL, pcie_ctrl);
        }

        dd_dev_dbg(dd, "%s: program XMT margin, CcePcieCtrl 0x%llx\n",
                   fname, pcie_ctrl);
}

/*
 * Do all the steps needed to transition the PCIe link to Gen3 speed.
 */
int do_pcie_gen3_transition(struct hfi1_devdata *dd)
{
        struct pci_dev *parent = dd->pcidev->bus->self;
        u64 fw_ctrl;
        u64 reg, therm;
        u32 reg32, fs, lf;
        u32 status, err;
        int ret;
        int do_retry, retry_count = 0;
        int intnum = 0;

        uint default_pset;
        uint pset = pcie_pset;
        u16 target_vector, target_speed;
        u16 lnkctl2, vendor;
        u8 div;
        const u8 (*eq)[3];
        const u8 (*ctle_tunings)[4];
        uint static_ctle_mode;
        int return_error = 0;
        u32 target_width;

        /* PCIe Gen3 is for the ASIC only */
        if (dd->icode != ICODE_RTL_SILICON)
                return 0;

        if (pcie_target == 1) {                 /* target Gen1 */
                target_vector = PCI_EXP_LNKCTL2_TLS_2_5GT;
                target_speed = 2500;
        } else if (pcie_target == 2) {          /* target Gen2 */
                target_vector = PCI_EXP_LNKCTL2_TLS_5_0GT;
                target_speed = 5000;
        } else if (pcie_target == 3) {          /* target Gen3 */
                target_vector = PCI_EXP_LNKCTL2_TLS_8_0GT;
                target_speed = 8000;
        } else {
                /* off or invalid target - skip */
                dd_dev_info(dd, "%s: Skipping PCIe transition\n", __func__);
                return 0;
        }

        /* if already at target speed, done (unless forced) */
        if (dd->lbus_speed == target_speed) {
                dd_dev_info(dd, "%s: PCIe already at gen%d, %s\n", __func__,
                            pcie_target,
                            pcie_force ? "re-doing anyway" : "skipping");
                if (!pcie_force)
                        return 0;
        }

        /*
         * The driver cannot do the transition if it has no access to the
         * upstream component
         */
        if (!parent) {
                dd_dev_info(dd, "%s: No upstream, Can't do gen3 transition\n",
                            __func__);
                return 0;
        }

        /* Previous Gen1/Gen2 bus width */
        target_width = dd->lbus_width;

        /*
         * Do the Gen3 transition.  Steps are those of the PCIe Gen3
         * recipe.
         */

        /* step 1: pcie link working in gen1/gen2 */

        /* step 2: if either side is not capable of Gen3, done */
        if (pcie_target == 3 && !dd->link_gen3_capable) {
                dd_dev_err(dd, "The PCIe link is not Gen3 capable\n");
                ret = -ENOSYS;
                goto done_no_mutex;
        }

        /* hold the SBus resource across the firmware download and SBR */
        ret = acquire_chip_resource(dd, CR_SBUS, SBUS_TIMEOUT);
        if (ret) {
                dd_dev_err(dd, "%s: unable to acquire SBus resource\n",
                           __func__);
                return ret;
        }

        /* make sure thermal polling is not causing interrupts */
        therm = read_csr(dd, ASIC_CFG_THERM_POLL_EN);
        if (therm) {
                write_csr(dd, ASIC_CFG_THERM_POLL_EN, 0x0);
                msleep(100);
                dd_dev_info(dd, "%s: Disabled therm polling\n",
                            __func__);
        }

retry:
        /* the SBus download will reset the spico for thermal */

        /* step 3: download SBus Master firmware */
        /* step 4: download PCIe Gen3 SerDes firmware */
        dd_dev_info(dd, "%s: downloading firmware\n", __func__);
        ret = load_pcie_firmware(dd);
        if (ret) {
                /* do not proceed if the firmware cannot be downloaded */
                return_error = 1;
                goto done;
        }

        /* step 5: set up device parameter settings */
        dd_dev_info(dd, "%s: setting PCIe registers\n", __func__);

        /*
         * PcieCfgSpcie1 - Link Control 3
         * Leave at reset value.  No need to set PerfEq - link equalization
         * will be performed automatically after the SBR when the target
         * speed is 8GT/s.
         */

        /* clear all 16 per-lane error bits (PCIe: Lane Error Status) */
        pci_write_config_dword(dd->pcidev, PCIE_CFG_SPCIE2, 0xffff);

        /* step 5a: Set Synopsys Port Logic registers */

        /*
         * PcieCfgRegPl2 - Port Force Link
         *
         * Set the low power field to 0x10 to avoid unnecessary power
         * management messages.  All other fields are zero.
         */
        reg32 = 0x10ul << PCIE_CFG_REG_PL2_LOW_PWR_ENT_CNT_SHIFT;
        pci_write_config_dword(dd->pcidev, PCIE_CFG_REG_PL2, reg32);

        /*
         * PcieCfgRegPl100 - Gen3 Control
         *
         * turn off PcieCfgRegPl100.Gen3ZRxDcNonCompl
         * turn on PcieCfgRegPl100.EqEieosCnt
         * Everything else zero.
         */
        reg32 = PCIE_CFG_REG_PL100_EQ_EIEOS_CNT_SMASK;
        pci_write_config_dword(dd->pcidev, PCIE_CFG_REG_PL100, reg32);

        /*
         * PcieCfgRegPl101 - Gen3 EQ FS and LF
         * PcieCfgRegPl102 - Gen3 EQ Presets to Coefficients Mapping
         * PcieCfgRegPl103 - Gen3 EQ Preset Index
         * PcieCfgRegPl105 - Gen3 EQ Status
         *
         * Give initial EQ settings.
         */
        if (dd->pcidev->device == PCI_DEVICE_ID_INTEL0) { /* discrete */
                /* 1000mV, FS=24, LF = 8 */
                fs = 24;
                lf = 8;
                div = 3;
                eq = discrete_preliminary_eq;
                default_pset = DEFAULT_DISCRETE_PSET;
                ctle_tunings = discrete_ctle_tunings;
                /* bit 0 - discrete on/off */
                static_ctle_mode = pcie_ctle & 0x1;
        } else {
                /* 400mV, FS=29, LF = 9 */
                fs = 29;
                lf = 9;
                div = 1;
                eq = integrated_preliminary_eq;
                default_pset = DEFAULT_MCP_PSET;
                ctle_tunings = integrated_ctle_tunings;
                /* bit 1 - integrated on/off */
                static_ctle_mode = (pcie_ctle >> 1) & 0x1;
        }
        pci_write_config_dword(dd->pcidev, PCIE_CFG_REG_PL101,
                               (fs <<
                                PCIE_CFG_REG_PL101_GEN3_EQ_LOCAL_FS_SHIFT) |
                               (lf <<
                                PCIE_CFG_REG_PL101_GEN3_EQ_LOCAL_LF_SHIFT));
        ret = load_eq_table(dd, eq, fs, div);
        if (ret)
                goto done;

        /*
         * PcieCfgRegPl106 - Gen3 EQ Control
         *
         * Set Gen3EqPsetReqVec, leave other fields 0.
         */
        if (pset == UNSET_PSET)
                pset = default_pset;
        if (pset > 10) {        /* valid range is 0-10, inclusive */
                dd_dev_err(dd, "%s: Invalid Eq Pset %u, setting to %d\n",
                           __func__, pset, default_pset);
                pset = default_pset;
        }
        dd_dev_info(dd, "%s: using EQ Pset %u\n", __func__, pset);
        pci_write_config_dword(dd->pcidev, PCIE_CFG_REG_PL106,
                               ((1 << pset) <<
                        PCIE_CFG_REG_PL106_GEN3_EQ_PSET_REQ_VEC_SHIFT) |
                        PCIE_CFG_REG_PL106_GEN3_EQ_EVAL2MS_DISABLE_SMASK |
                        PCIE_CFG_REG_PL106_GEN3_EQ_PHASE23_EXIT_MODE_SMASK);

        /*
         * step 5b: Do post firmware download steps via SBus
         */
        dd_dev_info(dd, "%s: doing pcie post steps\n", __func__);
        pcie_post_steps(dd);

        /*
         * step 5c: Program gasket interrupts
         */
        /* set the Rx Bit Rate to REFCLK ratio */
        write_gasket_interrupt(dd, intnum++, 0x0006, 0x0050);
        /* disable pCal for PCIe Gen3 RX equalization */
        /* select adaptive or static CTLE */
        write_gasket_interrupt(dd, intnum++, 0x0026,
                               0x5b01 | (static_ctle_mode << 3));
        /*
         * Enable iCal for PCIe Gen3 RX equalization, and set which
         * evaluation of RX_EQ_EVAL will launch the iCal procedure.
         */
        write_gasket_interrupt(dd, intnum++, 0x0026, 0x5202);

        if (static_ctle_mode) {
                /* apply static CTLE tunings */
                u8 pcie_dc, pcie_lf, pcie_hf, pcie_bw;

                pcie_dc = ctle_tunings[pset][0];
                pcie_lf = ctle_tunings[pset][1];
                pcie_hf = ctle_tunings[pset][2];
                pcie_bw = ctle_tunings[pset][3];
                write_gasket_interrupt(dd, intnum++, 0x0026, 0x0200 | pcie_dc);
                write_gasket_interrupt(dd, intnum++, 0x0026, 0x0100 | pcie_lf);
                write_gasket_interrupt(dd, intnum++, 0x0026, 0x0000 | pcie_hf);
                write_gasket_interrupt(dd, intnum++, 0x0026, 0x5500 | pcie_bw);
        }

        /* terminate list */
        write_gasket_interrupt(dd, intnum++, 0x0000, 0x0000);

        /*
         * step 5d: program XMT margin
         */
        write_xmt_margin(dd, __func__);

        /*
         * step 5e: disable active state power management (ASPM). It
         * will be enabled if required later
         */
        dd_dev_info(dd, "%s: clearing ASPM\n", __func__);
        aspm_hw_disable_l1(dd);

        /*
         * step 5f: clear DirectSpeedChange
         * PcieCfgRegPl67.DirectSpeedChange must be zero to prevent the
         * change in the speed target from starting before we are ready.
         * This field defaults to 0 and we are not changing it, so nothing
         * needs to be done.
         */

        /* step 5g: Set target link speed */
        /*
         * Set target link speed to be target on both device and parent.
         * On setting the parent: Some system BIOSs "helpfully" set the
         * parent target speed to Gen2 to match the ASIC's initial speed.
         * We can set the target Gen3 because we have already checked
         * that it is Gen3 capable earlier.
         */
        dd_dev_info(dd, "%s: setting parent target link speed\n", __func__);
        ret = pcie_capability_read_word(parent, PCI_EXP_LNKCTL2, &lnkctl2);
        if (ret) {
                dd_dev_err(dd, "Unable to read from PCI config\n");
                return_error = 1;
                goto done;
        }

        dd_dev_info(dd, "%s: ..old link control2: 0x%x\n", __func__,
                    (u32)lnkctl2);
        /* only write to parent if target is not as high as ours */
        if ((lnkctl2 & PCI_EXP_LNKCTL2_TLS) < target_vector) {
                lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS;
                lnkctl2 |= target_vector;
                dd_dev_info(dd, "%s: ..new link control2: 0x%x\n", __func__,
                            (u32)lnkctl2);
                ret = pcie_capability_write_word(parent,
                                                 PCI_EXP_LNKCTL2, lnkctl2);
                if (ret) {
                        dd_dev_err(dd, "Unable to write to PCI config\n");
                        return_error = 1;
                        goto done;
                }
        } else {
                dd_dev_info(dd, "%s: ..target speed is OK\n", __func__);
        }

        dd_dev_info(dd, "%s: setting target link speed\n", __func__);
        ret = pcie_capability_read_word(dd->pcidev, PCI_EXP_LNKCTL2, &lnkctl2);
        if (ret) {
                dd_dev_err(dd, "Unable to read from PCI config\n");
                return_error = 1;
                goto done;
        }

        dd_dev_info(dd, "%s: ..old link control2: 0x%x\n", __func__,
                    (u32)lnkctl2);
        lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS;
        lnkctl2 |= target_vector;
        dd_dev_info(dd, "%s: ..new link control2: 0x%x\n", __func__,
                    (u32)lnkctl2);
        ret = pcie_capability_write_word(dd->pcidev, PCI_EXP_LNKCTL2, lnkctl2);
        if (ret) {
                dd_dev_err(dd, "Unable to write to PCI config\n");
                return_error = 1;
                goto done;
        }

        /* step 5h: arm gasket logic */
        /* hold DC in reset across the SBR */
        write_csr(dd, CCE_DC_CTRL, CCE_DC_CTRL_DC_RESET_SMASK);
        (void)read_csr(dd, CCE_DC_CTRL); /* DC reset hold */
        /* save firmware control across the SBR */
        fw_ctrl = read_csr(dd, MISC_CFG_FW_CTRL);

        dd_dev_info(dd, "%s: arming gasket logic\n", __func__);
        arm_gasket_logic(dd);

        /*
         * step 6: quiesce PCIe link
         * The chip has already been reset, so there will be no traffic
         * from the chip.  Linux has no easy way to enforce that it will
         * not try to access the device, so we just need to hope it doesn't
         * do it while we are doing the reset.
         */

        /*
         * step 7: initiate the secondary bus reset (SBR)
         * step 8: hardware brings the links back up
         * step 9: wait for link speed transition to be complete
         */
        dd_dev_info(dd, "%s: calling trigger_sbr\n", __func__);
        ret = trigger_sbr(dd);
        if (ret)
                goto done;

        /* step 10: decide what to do next */

        /* check if we can read PCI space */
        ret = pci_read_config_word(dd->pcidev, PCI_VENDOR_ID, &vendor);
        if (ret) {
                dd_dev_info(dd,
                            "%s: read of VendorID failed after SBR, err %d\n",
                            __func__, ret);
                return_error = 1;
                goto done;
        }
        if (vendor == 0xffff) {
                dd_dev_info(dd, "%s: VendorID is all 1s after SBR\n", __func__);
                return_error = 1;
                ret = -EIO;
                goto done;
        }

        /* restore PCI space registers we know were reset */
        dd_dev_info(dd, "%s: calling restore_pci_variables\n", __func__);
        ret = restore_pci_variables(dd);
        if (ret) {
                dd_dev_err(dd, "%s: Could not restore PCI variables\n",
                           __func__);
                return_error = 1;
                goto done;
        }

        /* restore firmware control */
        write_csr(dd, MISC_CFG_FW_CTRL, fw_ctrl);

        /*
         * Check the gasket block status.
         *
         * This is the first CSR read after the SBR.  If the read returns
         * all 1s (fails), the link did not make it back.
         *
         * Once we're sure we can read and write, clear the DC reset after
         * the SBR.  Then check for any per-lane errors. Then look over
         * the status.
         */
        reg = read_csr(dd, ASIC_PCIE_SD_HOST_STATUS);
        dd_dev_info(dd, "%s: gasket block status: 0x%llx\n", __func__, reg);
        if (reg == ~0ull) {     /* PCIe read failed/timeout */
                dd_dev_err(dd, "SBR failed - unable to read from device\n");
                return_error = 1;
                ret = -ENOSYS;
                goto done;
        }

        /* clear the DC reset */
        write_csr(dd, CCE_DC_CTRL, 0);

        /* Set the LED off */
        setextled(dd, 0);

        /* check for any per-lane errors */
        ret = pci_read_config_dword(dd->pcidev, PCIE_CFG_SPCIE2, &reg32);
        if (ret) {
                dd_dev_err(dd, "Unable to read from PCI config\n");
                return_error = 1;
                goto done;
        }

        dd_dev_info(dd, "%s: per-lane errors: 0x%x\n", __func__, reg32);

        /* extract status, look for our HFI */
        status = (reg >> ASIC_PCIE_SD_HOST_STATUS_FW_DNLD_STS_SHIFT)
                        & ASIC_PCIE_SD_HOST_STATUS_FW_DNLD_STS_MASK;
        if ((status & (1 << dd->hfi1_id)) == 0) {
                dd_dev_err(dd,
                           "%s: gasket status 0x%x, expecting 0x%x\n",
                           __func__, status, 1 << dd->hfi1_id);
                ret = -EIO;
                goto done;
        }

        /* extract error */
        err = (reg >> ASIC_PCIE_SD_HOST_STATUS_FW_DNLD_ERR_SHIFT)
                & ASIC_PCIE_SD_HOST_STATUS_FW_DNLD_ERR_MASK;
        if (err) {
                dd_dev_err(dd, "%s: gasket error %d\n", __func__, err);
                ret = -EIO;
                goto done;
        }

        /* update our link information cache */
        update_lbus_info(dd);
        dd_dev_info(dd, "%s: new speed and width: %s\n", __func__,
                    dd->lbus_info);

        if (dd->lbus_speed != target_speed ||
            dd->lbus_width < target_width) { /* not target */
                /* maybe retry */
                do_retry = retry_count < pcie_retry;
                dd_dev_err(dd, "PCIe link speed or width did not match target%s\n",
                           do_retry ? ", retrying" : "");
                retry_count++;
                if (do_retry) {
                        msleep(100); /* allow time to settle */
                        goto retry;
                }
                ret = -EIO;
        }

done:
        if (therm) {
                write_csr(dd, ASIC_CFG_THERM_POLL_EN, 0x1);
                msleep(100);
                dd_dev_info(dd, "%s: Re-enable therm polling\n",
                            __func__);
        }
        release_chip_resource(dd, CR_SBUS);
done_no_mutex:
        /* return no error if it is OK to be at current speed */
        if (ret && !return_error) {
                dd_dev_err(dd, "Proceeding at current speed PCIe speed\n");
                ret = 0;
        }

        dd_dev_info(dd, "%s: done\n", __func__);
        return ret;
}