/*
 * 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.
 *
 */
#ifndef _ASPM_H
#define _ASPM_H

#include "hfi.h"

extern uint aspm_mode;

enum aspm_mode {
        ASPM_MODE_DISABLED = 0, /* ASPM always disabled, performance mode */
        ASPM_MODE_ENABLED = 1,  /* ASPM always enabled, power saving mode */
        ASPM_MODE_DYNAMIC = 2,  /* ASPM enabled/disabled dynamically */
};

/* Time after which the timer interrupt will re-enable ASPM */
#define ASPM_TIMER_MS 1000
/* Time for which interrupts are ignored after a timer has been scheduled */
#define ASPM_RESCHED_TIMER_MS (ASPM_TIMER_MS / 2)
/* Two interrupts within this time trigger ASPM disable */
#define ASPM_TRIGGER_MS 1
#define ASPM_TRIGGER_NS (ASPM_TRIGGER_MS * 1000 * 1000ull)
#define ASPM_L1_SUPPORTED(reg) \
        (((reg & PCI_EXP_LNKCAP_ASPMS) >> 10) & 0x2)

static inline bool aspm_hw_l1_supported(struct hfi1_devdata *dd)
{
        struct pci_dev *parent = dd->pcidev->bus->self;
        u32 up, dn;

        /*
         * If the driver does not have access to the upstream component,
         * it cannot support ASPM L1 at all.
         */
        if (!parent)
                return false;

        pcie_capability_read_dword(dd->pcidev, PCI_EXP_LNKCAP, &dn);
        dn = ASPM_L1_SUPPORTED(dn);

        pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, &up);
        up = ASPM_L1_SUPPORTED(up);

        /* ASPM works on A-step but is reported as not supported */
        return (!!dn || is_ax(dd)) && !!up;
}

/* Set L1 entrance latency for slower entry to L1 */
static inline void aspm_hw_set_l1_ent_latency(struct hfi1_devdata *dd)
{
        u32 l1_ent_lat = 0x4u;
        u32 reg32;

        pci_read_config_dword(dd->pcidev, PCIE_CFG_REG_PL3, &reg32);
        reg32 &= ~PCIE_CFG_REG_PL3_L1_ENT_LATENCY_SMASK;
        reg32 |= l1_ent_lat << PCIE_CFG_REG_PL3_L1_ENT_LATENCY_SHIFT;
        pci_write_config_dword(dd->pcidev, PCIE_CFG_REG_PL3, reg32);
}

static inline void aspm_hw_enable_l1(struct hfi1_devdata *dd)
{
        struct pci_dev *parent = dd->pcidev->bus->self;

        /*
         * If the driver does not have access to the upstream component,
         * it cannot support ASPM L1 at all.
         */
        if (!parent)
                return;

        /* Enable ASPM L1 first in upstream component and then downstream */
        pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
                                           PCI_EXP_LNKCTL_ASPMC,
                                           PCI_EXP_LNKCTL_ASPM_L1);
        pcie_capability_clear_and_set_word(dd->pcidev, PCI_EXP_LNKCTL,
                                           PCI_EXP_LNKCTL_ASPMC,
                                           PCI_EXP_LNKCTL_ASPM_L1);
}

static inline void aspm_hw_disable_l1(struct hfi1_devdata *dd)
{
        struct pci_dev *parent = dd->pcidev->bus->self;

        /* Disable ASPM L1 first in downstream component and then upstream */
        pcie_capability_clear_and_set_word(dd->pcidev, PCI_EXP_LNKCTL,
                                           PCI_EXP_LNKCTL_ASPMC, 0x0);
        if (parent)
                pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL,
                                                   PCI_EXP_LNKCTL_ASPMC, 0x0);
}

static inline void aspm_enable(struct hfi1_devdata *dd)
{
        if (dd->aspm_enabled || aspm_mode == ASPM_MODE_DISABLED ||
            !dd->aspm_supported)
                return;

        aspm_hw_enable_l1(dd);
        dd->aspm_enabled = true;
}

static inline void aspm_disable(struct hfi1_devdata *dd)
{
        if (!dd->aspm_enabled || aspm_mode == ASPM_MODE_ENABLED)
                return;

        aspm_hw_disable_l1(dd);
        dd->aspm_enabled = false;
}

static inline void aspm_disable_inc(struct hfi1_devdata *dd)
{
        unsigned long flags;

        spin_lock_irqsave(&dd->aspm_lock, flags);
        aspm_disable(dd);
        atomic_inc(&dd->aspm_disabled_cnt);
        spin_unlock_irqrestore(&dd->aspm_lock, flags);
}

static inline void aspm_enable_dec(struct hfi1_devdata *dd)
{
        unsigned long flags;

        spin_lock_irqsave(&dd->aspm_lock, flags);
        if (atomic_dec_and_test(&dd->aspm_disabled_cnt))
                aspm_enable(dd);
        spin_unlock_irqrestore(&dd->aspm_lock, flags);
}

/* ASPM processing for each receive context interrupt */
static inline void aspm_ctx_disable(struct hfi1_ctxtdata *rcd)
{
        bool restart_timer;
        bool close_interrupts;
        unsigned long flags;
        ktime_t now, prev;

        /* Quickest exit for minimum impact */
        if (!rcd->aspm_intr_supported)
                return;

        spin_lock_irqsave(&rcd->aspm_lock, flags);
        /* PSM contexts are open */
        if (!rcd->aspm_intr_enable)
                goto unlock;

        prev = rcd->aspm_ts_last_intr;
        now = ktime_get();
        rcd->aspm_ts_last_intr = now;

        /* An interrupt pair close together in time */
        close_interrupts = ktime_to_ns(ktime_sub(now, prev)) < ASPM_TRIGGER_NS;

        /* Don't push out our timer till this much time has elapsed */
        restart_timer = ktime_to_ns(ktime_sub(now, rcd->aspm_ts_timer_sched)) >
                                    ASPM_RESCHED_TIMER_MS * NSEC_PER_MSEC;
        restart_timer = restart_timer && close_interrupts;

        /* Disable ASPM and schedule timer */
        if (rcd->aspm_enabled && close_interrupts) {
                aspm_disable_inc(rcd->dd);
                rcd->aspm_enabled = false;
                restart_timer = true;
        }

        if (restart_timer) {
                mod_timer(&rcd->aspm_timer,
                          jiffies + msecs_to_jiffies(ASPM_TIMER_MS));
                rcd->aspm_ts_timer_sched = now;
        }
unlock:
        spin_unlock_irqrestore(&rcd->aspm_lock, flags);
}

/* Timer function for re-enabling ASPM in the absence of interrupt activity */
static inline void aspm_ctx_timer_function(unsigned long data)
{
        struct hfi1_ctxtdata *rcd = (struct hfi1_ctxtdata *)data;
        unsigned long flags;

        spin_lock_irqsave(&rcd->aspm_lock, flags);
        aspm_enable_dec(rcd->dd);
        rcd->aspm_enabled = true;
        spin_unlock_irqrestore(&rcd->aspm_lock, flags);
}

/* Disable interrupt processing for verbs contexts when PSM contexts are open */
static inline void aspm_disable_all(struct hfi1_devdata *dd)
{
        struct hfi1_ctxtdata *rcd;
        unsigned long flags;
        unsigned i;

        for (i = 0; i < dd->first_user_ctxt; i++) {
                rcd = dd->rcd[i];
                del_timer_sync(&rcd->aspm_timer);
                spin_lock_irqsave(&rcd->aspm_lock, flags);
                rcd->aspm_intr_enable = false;
                spin_unlock_irqrestore(&rcd->aspm_lock, flags);
        }

        aspm_disable(dd);
        atomic_set(&dd->aspm_disabled_cnt, 0);
}

/* Re-enable interrupt processing for verbs contexts */
static inline void aspm_enable_all(struct hfi1_devdata *dd)
{
        struct hfi1_ctxtdata *rcd;
        unsigned long flags;
        unsigned i;

        aspm_enable(dd);

        if (aspm_mode != ASPM_MODE_DYNAMIC)
                return;

        for (i = 0; i < dd->first_user_ctxt; i++) {
                rcd = dd->rcd[i];
                spin_lock_irqsave(&rcd->aspm_lock, flags);
                rcd->aspm_intr_enable = true;
                rcd->aspm_enabled = true;
                spin_unlock_irqrestore(&rcd->aspm_lock, flags);
        }
}

static inline void aspm_ctx_init(struct hfi1_ctxtdata *rcd)
{
        spin_lock_init(&rcd->aspm_lock);
        setup_timer(&rcd->aspm_timer, aspm_ctx_timer_function,
                    (unsigned long)rcd);
        rcd->aspm_intr_supported = rcd->dd->aspm_supported &&
                aspm_mode == ASPM_MODE_DYNAMIC &&
                rcd->ctxt < rcd->dd->first_user_ctxt;
}

static inline void aspm_init(struct hfi1_devdata *dd)
{
        unsigned i;

        spin_lock_init(&dd->aspm_lock);
        dd->aspm_supported = aspm_hw_l1_supported(dd);

        for (i = 0; i < dd->first_user_ctxt; i++)
                aspm_ctx_init(dd->rcd[i]);

        /* Start with ASPM disabled */
        aspm_hw_set_l1_ent_latency(dd);
        dd->aspm_enabled = false;
        aspm_hw_disable_l1(dd);

        /* Now turn on ASPM if configured */
        aspm_enable_all(dd);
}

static inline void aspm_exit(struct hfi1_devdata *dd)
{
        aspm_disable_all(dd);

        /* Turn on ASPM on exit to conserve power */
        aspm_enable(dd);
}

#endif /* _ASPM_H */