// SPDX-License-Identifier: GPL-2.0-only
/*
 * Thunderbolt driver - NHI driver
 *
 * The NHI (native host interface) is the pci device that allows us to send and
 * receive frames from the thunderbolt bus.
 *
 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
 * Copyright (C) 2018, Intel Corporation
 */

#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/property.h>

#include "nhi.h"
#include "nhi_regs.h"
#include "tb.h"

#define RING_TYPE(ring) ((ring)->is_tx ? "TX ring" : "RX ring")

#define RING_FIRST_USABLE_HOPID 1

/*
 * Minimal number of vectors when we use MSI-X. Two for control channel
 * Rx/Tx and the rest four are for cross domain DMA paths.
 */
#define MSIX_MIN_VECS           6
#define MSIX_MAX_VECS           16

#define NHI_MAILBOX_TIMEOUT     500 /* ms */

#define QUIRK_AUTO_CLEAR_INT    BIT(0)

static int ring_interrupt_index(struct tb_ring *ring)
{
        int bit = ring->hop;
        if (!ring->is_tx)
                bit += ring->nhi->hop_count;
        return bit;
}

/*
 * ring_interrupt_active() - activate/deactivate interrupts for a single ring
 *
 * ring->nhi->lock must be held.
 */
static void ring_interrupt_active(struct tb_ring *ring, bool active)
{
        int reg = REG_RING_INTERRUPT_BASE +
                  ring_interrupt_index(ring) / 32 * 4;
        int bit = ring_interrupt_index(ring) & 31;
        int mask = 1 << bit;
        u32 old, new;

        if (ring->irq > 0) {
                u32 step, shift, ivr, misc;
                void __iomem *ivr_base;
                int index;

                if (ring->is_tx)
                        index = ring->hop;
                else
                        index = ring->hop + ring->nhi->hop_count;

                if (ring->nhi->quirks & QUIRK_AUTO_CLEAR_INT) {
                        /*
                         * Ask the hardware to clear interrupt status
                         * bits automatically since we already know
                         * which interrupt was triggered.
                         */
                        misc = ioread32(ring->nhi->iobase + REG_DMA_MISC);
                        if (!(misc & REG_DMA_MISC_INT_AUTO_CLEAR)) {
                                misc |= REG_DMA_MISC_INT_AUTO_CLEAR;
                                iowrite32(misc, ring->nhi->iobase + REG_DMA_MISC);
                        }
                }

                ivr_base = ring->nhi->iobase + REG_INT_VEC_ALLOC_BASE;
                step = index / REG_INT_VEC_ALLOC_REGS * REG_INT_VEC_ALLOC_BITS;
                shift = index % REG_INT_VEC_ALLOC_REGS * REG_INT_VEC_ALLOC_BITS;
                ivr = ioread32(ivr_base + step);
                ivr &= ~(REG_INT_VEC_ALLOC_MASK << shift);
                if (active)
                        ivr |= ring->vector << shift;
                iowrite32(ivr, ivr_base + step);
        }

        old = ioread32(ring->nhi->iobase + reg);
        if (active)
                new = old | mask;
        else
                new = old & ~mask;

        dev_dbg(&ring->nhi->pdev->dev,
                "%s interrupt at register %#x bit %d (%#x -> %#x)\n",
                active ? "enabling" : "disabling", reg, bit, old, new);

        if (new == old)
                dev_WARN(&ring->nhi->pdev->dev,
                                         "interrupt for %s %d is already %s\n",
                                         RING_TYPE(ring), ring->hop,
                                         active ? "enabled" : "disabled");
        iowrite32(new, ring->nhi->iobase + reg);
}

/*
 * nhi_disable_interrupts() - disable interrupts for all rings
 *
 * Use only during init and shutdown.
 */
static void nhi_disable_interrupts(struct tb_nhi *nhi)
{
        int i = 0;
        /* disable interrupts */
        for (i = 0; i < RING_INTERRUPT_REG_COUNT(nhi); i++)
                iowrite32(0, nhi->iobase + REG_RING_INTERRUPT_BASE + 4 * i);

        /* clear interrupt status bits */
        for (i = 0; i < RING_NOTIFY_REG_COUNT(nhi); i++)
                ioread32(nhi->iobase + REG_RING_NOTIFY_BASE + 4 * i);
}

/* ring helper methods */

static void __iomem *ring_desc_base(struct tb_ring *ring)
{
        void __iomem *io = ring->nhi->iobase;
        io += ring->is_tx ? REG_TX_RING_BASE : REG_RX_RING_BASE;
        io += ring->hop * 16;
        return io;
}

static void __iomem *ring_options_base(struct tb_ring *ring)
{
        void __iomem *io = ring->nhi->iobase;
        io += ring->is_tx ? REG_TX_OPTIONS_BASE : REG_RX_OPTIONS_BASE;
        io += ring->hop * 32;
        return io;
}

static void ring_iowrite_cons(struct tb_ring *ring, u16 cons)
{
        /*
         * The other 16-bits in the register is read-only and writes to it
         * are ignored by the hardware so we can save one ioread32() by
         * filling the read-only bits with zeroes.
         */
        iowrite32(cons, ring_desc_base(ring) + 8);
}

static void ring_iowrite_prod(struct tb_ring *ring, u16 prod)
{
        /* See ring_iowrite_cons() above for explanation */
        iowrite32(prod << 16, ring_desc_base(ring) + 8);
}

static void ring_iowrite32desc(struct tb_ring *ring, u32 value, u32 offset)
{
        iowrite32(value, ring_desc_base(ring) + offset);
}

static void ring_iowrite64desc(struct tb_ring *ring, u64 value, u32 offset)
{
        iowrite32(value, ring_desc_base(ring) + offset);
        iowrite32(value >> 32, ring_desc_base(ring) + offset + 4);
}

static void ring_iowrite32options(struct tb_ring *ring, u32 value, u32 offset)
{
        iowrite32(value, ring_options_base(ring) + offset);
}

static bool ring_full(struct tb_ring *ring)
{
        return ((ring->head + 1) % ring->size) == ring->tail;
}

static bool ring_empty(struct tb_ring *ring)
{
        return ring->head == ring->tail;
}

/*
 * ring_write_descriptors() - post frames from ring->queue to the controller
 *
 * ring->lock is held.
 */
static void ring_write_descriptors(struct tb_ring *ring)
{
        struct ring_frame *frame, *n;
        struct ring_desc *descriptor;
        list_for_each_entry_safe(frame, n, &ring->queue, list) {
                if (ring_full(ring))
                        break;
                list_move_tail(&frame->list, &ring->in_flight);
                descriptor = &ring->descriptors[ring->head];
                descriptor->phys = frame->buffer_phy;
                descriptor->time = 0;
                descriptor->flags = RING_DESC_POSTED | RING_DESC_INTERRUPT;
                if (ring->is_tx) {
                        descriptor->length = frame->size;
                        descriptor->eof = frame->eof;
                        descriptor->sof = frame->sof;
                }
                ring->head = (ring->head + 1) % ring->size;
                if (ring->is_tx)
                        ring_iowrite_prod(ring, ring->head);
                else
                        ring_iowrite_cons(ring, ring->head);
        }
}

/*
 * ring_work() - progress completed frames
 *
 * If the ring is shutting down then all frames are marked as canceled and
 * their callbacks are invoked.
 *
 * Otherwise we collect all completed frame from the ring buffer, write new
 * frame to the ring buffer and invoke the callbacks for the completed frames.
 */
static void ring_work(struct work_struct *work)
{
        struct tb_ring *ring = container_of(work, typeof(*ring), work);
        struct ring_frame *frame;
        bool canceled = false;
        unsigned long flags;
        LIST_HEAD(done);

        spin_lock_irqsave(&ring->lock, flags);

        if (!ring->running) {
                /*  Move all frames to done and mark them as canceled. */
                list_splice_tail_init(&ring->in_flight, &done);
                list_splice_tail_init(&ring->queue, &done);
                canceled = true;
                goto invoke_callback;
        }

        while (!ring_empty(ring)) {
                if (!(ring->descriptors[ring->tail].flags
                                & RING_DESC_COMPLETED))
                        break;
                frame = list_first_entry(&ring->in_flight, typeof(*frame),
                                         list);
                list_move_tail(&frame->list, &done);
                if (!ring->is_tx) {
                        frame->size = ring->descriptors[ring->tail].length;
                        frame->eof = ring->descriptors[ring->tail].eof;
                        frame->sof = ring->descriptors[ring->tail].sof;
                        frame->flags = ring->descriptors[ring->tail].flags;
                }
                ring->tail = (ring->tail + 1) % ring->size;
        }
        ring_write_descriptors(ring);

invoke_callback:
        /* allow callbacks to schedule new work */
        spin_unlock_irqrestore(&ring->lock, flags);
        while (!list_empty(&done)) {
                frame = list_first_entry(&done, typeof(*frame), list);
                /*
                 * The callback may reenqueue or delete frame.
                 * Do not hold on to it.
                 */
                list_del_init(&frame->list);
                if (frame->callback)
                        frame->callback(ring, frame, canceled);
        }
}

int __tb_ring_enqueue(struct tb_ring *ring, struct ring_frame *frame)
{
        unsigned long flags;
        int ret = 0;

        spin_lock_irqsave(&ring->lock, flags);
        if (ring->running) {
                list_add_tail(&frame->list, &ring->queue);
                ring_write_descriptors(ring);
        } else {
                ret = -ESHUTDOWN;
        }
        spin_unlock_irqrestore(&ring->lock, flags);
        return ret;
}
EXPORT_SYMBOL_GPL(__tb_ring_enqueue);

/**
 * tb_ring_poll() - Poll one completed frame from the ring
 * @ring: Ring to poll
 *
 * This function can be called when @start_poll callback of the @ring
 * has been called. It will read one completed frame from the ring and
 * return it to the caller. Returns %NULL if there is no more completed
 * frames.
 */
struct ring_frame *tb_ring_poll(struct tb_ring *ring)
{
        struct ring_frame *frame = NULL;
        unsigned long flags;

        spin_lock_irqsave(&ring->lock, flags);
        if (!ring->running)
                goto unlock;
        if (ring_empty(ring))
                goto unlock;

        if (ring->descriptors[ring->tail].flags & RING_DESC_COMPLETED) {
                frame = list_first_entry(&ring->in_flight, typeof(*frame),
                                         list);
                list_del_init(&frame->list);

                if (!ring->is_tx) {
                        frame->size = ring->descriptors[ring->tail].length;
                        frame->eof = ring->descriptors[ring->tail].eof;
                        frame->sof = ring->descriptors[ring->tail].sof;
                        frame->flags = ring->descriptors[ring->tail].flags;
                }

                ring->tail = (ring->tail + 1) % ring->size;
        }

unlock:
        spin_unlock_irqrestore(&ring->lock, flags);
        return frame;
}
EXPORT_SYMBOL_GPL(tb_ring_poll);

static void __ring_interrupt_mask(struct tb_ring *ring, bool mask)
{
        int idx = ring_interrupt_index(ring);
        int reg = REG_RING_INTERRUPT_BASE + idx / 32 * 4;
        int bit = idx % 32;
        u32 val;

        val = ioread32(ring->nhi->iobase + reg);
        if (mask)
                val &= ~BIT(bit);
        else
                val |= BIT(bit);
        iowrite32(val, ring->nhi->iobase + reg);
}

/* Both @nhi->lock and @ring->lock should be held */
static void __ring_interrupt(struct tb_ring *ring)
{
        if (!ring->running)
                return;

        if (ring->start_poll) {
                __ring_interrupt_mask(ring, true);
                ring->start_poll(ring->poll_data);
        } else {
                schedule_work(&ring->work);
        }
}

/**
 * tb_ring_poll_complete() - Re-start interrupt for the ring
 * @ring: Ring to re-start the interrupt
 *
 * This will re-start (unmask) the ring interrupt once the user is done
 * with polling.
 */
void tb_ring_poll_complete(struct tb_ring *ring)
{
        unsigned long flags;

        spin_lock_irqsave(&ring->nhi->lock, flags);
        spin_lock(&ring->lock);
        if (ring->start_poll)
                __ring_interrupt_mask(ring, false);
        spin_unlock(&ring->lock);
        spin_unlock_irqrestore(&ring->nhi->lock, flags);
}
EXPORT_SYMBOL_GPL(tb_ring_poll_complete);

static void ring_clear_msix(const struct tb_ring *ring)
{
        if (ring->nhi->quirks & QUIRK_AUTO_CLEAR_INT)
                return;

        if (ring->is_tx)
                ioread32(ring->nhi->iobase + REG_RING_NOTIFY_BASE);
        else
                ioread32(ring->nhi->iobase + REG_RING_NOTIFY_BASE +
                         4 * (ring->nhi->hop_count / 32));
}

static irqreturn_t ring_msix(int irq, void *data)
{
        struct tb_ring *ring = data;

        spin_lock(&ring->nhi->lock);
        ring_clear_msix(ring);
        spin_lock(&ring->lock);
        __ring_interrupt(ring);
        spin_unlock(&ring->lock);
        spin_unlock(&ring->nhi->lock);

        return IRQ_HANDLED;
}

static int ring_request_msix(struct tb_ring *ring, bool no_suspend)
{
        struct tb_nhi *nhi = ring->nhi;
        unsigned long irqflags;
        int ret;

        if (!nhi->pdev->msix_enabled)
                return 0;

        ret = ida_simple_get(&nhi->msix_ida, 0, MSIX_MAX_VECS, GFP_KERNEL);
        if (ret < 0)
                return ret;

        ring->vector = ret;

        ret = pci_irq_vector(ring->nhi->pdev, ring->vector);
        if (ret < 0)
                goto err_ida_remove;

        ring->irq = ret;

        irqflags = no_suspend ? IRQF_NO_SUSPEND : 0;
        ret = request_irq(ring->irq, ring_msix, irqflags, "thunderbolt", ring);
        if (ret)
                goto err_ida_remove;

        return 0;

err_ida_remove:
        ida_simple_remove(&nhi->msix_ida, ring->vector);

        return ret;
}

static void ring_release_msix(struct tb_ring *ring)
{
        if (ring->irq <= 0)
                return;

        free_irq(ring->irq, ring);
        ida_simple_remove(&ring->nhi->msix_ida, ring->vector);
        ring->vector = 0;
        ring->irq = 0;
}

static int nhi_alloc_hop(struct tb_nhi *nhi, struct tb_ring *ring)
{
        int ret = 0;

        spin_lock_irq(&nhi->lock);

        if (ring->hop < 0) {
                unsigned int i;

                /*
                 * Automatically allocate HopID from the non-reserved
                 * range 1 .. hop_count - 1.
                 */
                for (i = RING_FIRST_USABLE_HOPID; i < nhi->hop_count; i++) {
                        if (ring->is_tx) {
                                if (!nhi->tx_rings[i]) {
                                        ring->hop = i;
                                        break;
                                }
                        } else {
                                if (!nhi->rx_rings[i]) {
                                        ring->hop = i;
                                        break;
                                }
                        }
                }
        }

        if (ring->hop < 0 || ring->hop >= nhi->hop_count) {
                dev_warn(&nhi->pdev->dev, "invalid hop: %d\n", ring->hop);
                ret = -EINVAL;
                goto err_unlock;
        }
        if (ring->is_tx && nhi->tx_rings[ring->hop]) {
                dev_warn(&nhi->pdev->dev, "TX hop %d already allocated\n",
                         ring->hop);
                ret = -EBUSY;
                goto err_unlock;
        } else if (!ring->is_tx && nhi->rx_rings[ring->hop]) {
                dev_warn(&nhi->pdev->dev, "RX hop %d already allocated\n",
                         ring->hop);
                ret = -EBUSY;
                goto err_unlock;
        }

        if (ring->is_tx)
                nhi->tx_rings[ring->hop] = ring;
        else
                nhi->rx_rings[ring->hop] = ring;

err_unlock:
        spin_unlock_irq(&nhi->lock);

        return ret;
}

static struct tb_ring *tb_ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
                                     bool transmit, unsigned int flags,
                                     int e2e_tx_hop, u16 sof_mask, u16 eof_mask,
                                     void (*start_poll)(void *),
                                     void *poll_data)
{
        struct tb_ring *ring = NULL;

        dev_dbg(&nhi->pdev->dev, "allocating %s ring %d of size %d\n",
                transmit ? "TX" : "RX", hop, size);

        ring = kzalloc(sizeof(*ring), GFP_KERNEL);
        if (!ring)
                return NULL;

        spin_lock_init(&ring->lock);
        INIT_LIST_HEAD(&ring->queue);
        INIT_LIST_HEAD(&ring->in_flight);
        INIT_WORK(&ring->work, ring_work);

        ring->nhi = nhi;
        ring->hop = hop;
        ring->is_tx = transmit;
        ring->size = size;
        ring->flags = flags;
        ring->e2e_tx_hop = e2e_tx_hop;
        ring->sof_mask = sof_mask;
        ring->eof_mask = eof_mask;
        ring->head = 0;
        ring->tail = 0;
        ring->running = false;
        ring->start_poll = start_poll;
        ring->poll_data = poll_data;

        ring->descriptors = dma_alloc_coherent(&ring->nhi->pdev->dev,
                        size * sizeof(*ring->descriptors),
                        &ring->descriptors_dma, GFP_KERNEL | __GFP_ZERO);
        if (!ring->descriptors)
                goto err_free_ring;

        if (ring_request_msix(ring, flags & RING_FLAG_NO_SUSPEND))
                goto err_free_descs;

        if (nhi_alloc_hop(nhi, ring))
                goto err_release_msix;

        return ring;

err_release_msix:
        ring_release_msix(ring);
err_free_descs:
        dma_free_coherent(&ring->nhi->pdev->dev,
                          ring->size * sizeof(*ring->descriptors),
                          ring->descriptors, ring->descriptors_dma);
err_free_ring:
        kfree(ring);

        return NULL;
}

/**
 * tb_ring_alloc_tx() - Allocate DMA ring for transmit
 * @nhi: Pointer to the NHI the ring is to be allocated
 * @hop: HopID (ring) to allocate
 * @size: Number of entries in the ring
 * @flags: Flags for the ring
 */
struct tb_ring *tb_ring_alloc_tx(struct tb_nhi *nhi, int hop, int size,
                                 unsigned int flags)
{
        return tb_ring_alloc(nhi, hop, size, true, flags, 0, 0, 0, NULL, NULL);
}
EXPORT_SYMBOL_GPL(tb_ring_alloc_tx);

/**
 * tb_ring_alloc_rx() - Allocate DMA ring for receive
 * @nhi: Pointer to the NHI the ring is to be allocated
 * @hop: HopID (ring) to allocate. Pass %-1 for automatic allocation.
 * @size: Number of entries in the ring
 * @flags: Flags for the ring
 * @e2e_tx_hop: Transmit HopID when E2E is enabled in @flags
 * @sof_mask: Mask of PDF values that start a frame
 * @eof_mask: Mask of PDF values that end a frame
 * @start_poll: If not %NULL the ring will call this function when an
 *              interrupt is triggered and masked, instead of callback
 *              in each Rx frame.
 * @poll_data: Optional data passed to @start_poll
 */
struct tb_ring *tb_ring_alloc_rx(struct tb_nhi *nhi, int hop, int size,
                                 unsigned int flags, int e2e_tx_hop,
                                 u16 sof_mask, u16 eof_mask,
                                 void (*start_poll)(void *), void *poll_data)
{
        return tb_ring_alloc(nhi, hop, size, false, flags, e2e_tx_hop, sof_mask, eof_mask,
                             start_poll, poll_data);
}
EXPORT_SYMBOL_GPL(tb_ring_alloc_rx);

/**
 * tb_ring_start() - enable a ring
 * @ring: Ring to start
 *
 * Must not be invoked in parallel with tb_ring_stop().
 */
void tb_ring_start(struct tb_ring *ring)
{
        u16 frame_size;
        u32 flags;

        spin_lock_irq(&ring->nhi->lock);
        spin_lock(&ring->lock);
        if (ring->nhi->going_away)
                goto err;
        if (ring->running) {
                dev_WARN(&ring->nhi->pdev->dev, "ring already started\n");
                goto err;
        }
        dev_dbg(&ring->nhi->pdev->dev, "starting %s %d\n",
                RING_TYPE(ring), ring->hop);

        if (ring->flags & RING_FLAG_FRAME) {
                /* Means 4096 */
                frame_size = 0;
                flags = RING_FLAG_ENABLE;
        } else {
                frame_size = TB_FRAME_SIZE;
                flags = RING_FLAG_ENABLE | RING_FLAG_RAW;
        }

        ring_iowrite64desc(ring, ring->descriptors_dma, 0);
        if (ring->is_tx) {
                ring_iowrite32desc(ring, ring->size, 12);
                ring_iowrite32options(ring, 0, 4); /* time releated ? */
                ring_iowrite32options(ring, flags, 0);
        } else {
                u32 sof_eof_mask = ring->sof_mask << 16 | ring->eof_mask;

                ring_iowrite32desc(ring, (frame_size << 16) | ring->size, 12);
                ring_iowrite32options(ring, sof_eof_mask, 4);
                ring_iowrite32options(ring, flags, 0);
        }

        /*
         * Now that the ring valid bit is set we can configure E2E if
         * enabled for the ring.
         */
        if (ring->flags & RING_FLAG_E2E) {
                if (!ring->is_tx) {
                        u32 hop;

                        hop = ring->e2e_tx_hop << REG_RX_OPTIONS_E2E_HOP_SHIFT;
                        hop &= REG_RX_OPTIONS_E2E_HOP_MASK;
                        flags |= hop;

                        dev_dbg(&ring->nhi->pdev->dev,
                                "enabling E2E for %s %d with TX HopID %d\n",
                                RING_TYPE(ring), ring->hop, ring->e2e_tx_hop);
                } else {
                        dev_dbg(&ring->nhi->pdev->dev, "enabling E2E for %s %d\n",
                                RING_TYPE(ring), ring->hop);
                }

                flags |= RING_FLAG_E2E_FLOW_CONTROL;
                ring_iowrite32options(ring, flags, 0);
        }

        ring_interrupt_active(ring, true);
        ring->running = true;
err:
        spin_unlock(&ring->lock);
        spin_unlock_irq(&ring->nhi->lock);
}
EXPORT_SYMBOL_GPL(tb_ring_start);

/**
 * tb_ring_stop() - shutdown a ring
 * @ring: Ring to stop
 *
 * Must not be invoked from a callback.
 *
 * This method will disable the ring. Further calls to
 * tb_ring_tx/tb_ring_rx will return -ESHUTDOWN until ring_stop has been
 * called.
 *
 * All enqueued frames will be canceled and their callbacks will be executed
 * with frame->canceled set to true (on the callback thread). This method
 * returns only after all callback invocations have finished.
 */
void tb_ring_stop(struct tb_ring *ring)
{
        spin_lock_irq(&ring->nhi->lock);
        spin_lock(&ring->lock);
        dev_dbg(&ring->nhi->pdev->dev, "stopping %s %d\n",
                RING_TYPE(ring), ring->hop);
        if (ring->nhi->going_away)
                goto err;
        if (!ring->running) {
                dev_WARN(&ring->nhi->pdev->dev, "%s %d already stopped\n",
                         RING_TYPE(ring), ring->hop);
                goto err;
        }
        ring_interrupt_active(ring, false);

        ring_iowrite32options(ring, 0, 0);
        ring_iowrite64desc(ring, 0, 0);
        ring_iowrite32desc(ring, 0, 8);
        ring_iowrite32desc(ring, 0, 12);
        ring->head = 0;
        ring->tail = 0;
        ring->running = false;

err:
        spin_unlock(&ring->lock);
        spin_unlock_irq(&ring->nhi->lock);

        /*
         * schedule ring->work to invoke callbacks on all remaining frames.
         */
        schedule_work(&ring->work);
        flush_work(&ring->work);
}
EXPORT_SYMBOL_GPL(tb_ring_stop);

/*
 * tb_ring_free() - free ring
 *
 * When this method returns all invocations of ring->callback will have
 * finished.
 *
 * Ring must be stopped.
 *
 * Must NOT be called from ring_frame->callback!
 */
void tb_ring_free(struct tb_ring *ring)
{
        spin_lock_irq(&ring->nhi->lock);
        /*
         * Dissociate the ring from the NHI. This also ensures that
         * nhi_interrupt_work cannot reschedule ring->work.
         */
        if (ring->is_tx)
                ring->nhi->tx_rings[ring->hop] = NULL;
        else
                ring->nhi->rx_rings[ring->hop] = NULL;

        if (ring->running) {
                dev_WARN(&ring->nhi->pdev->dev, "%s %d still running\n",
                         RING_TYPE(ring), ring->hop);
        }
        spin_unlock_irq(&ring->nhi->lock);

        ring_release_msix(ring);

        dma_free_coherent(&ring->nhi->pdev->dev,
                          ring->size * sizeof(*ring->descriptors),
                          ring->descriptors, ring->descriptors_dma);

        ring->descriptors = NULL;
        ring->descriptors_dma = 0;


        dev_dbg(&ring->nhi->pdev->dev, "freeing %s %d\n", RING_TYPE(ring),
                ring->hop);

        /*
         * ring->work can no longer be scheduled (it is scheduled only
         * by nhi_interrupt_work, ring_stop and ring_msix). Wait for it
         * to finish before freeing the ring.
         */
        flush_work(&ring->work);
        kfree(ring);
}
EXPORT_SYMBOL_GPL(tb_ring_free);

/**
 * nhi_mailbox_cmd() - Send a command through NHI mailbox
 * @nhi: Pointer to the NHI structure
 * @cmd: Command to send
 * @data: Data to be send with the command
 *
 * Sends mailbox command to the firmware running on NHI. Returns %0 in
 * case of success and negative errno in case of failure.
 */
int nhi_mailbox_cmd(struct tb_nhi *nhi, enum nhi_mailbox_cmd cmd, u32 data)
{
        ktime_t timeout;
        u32 val;

        iowrite32(data, nhi->iobase + REG_INMAIL_DATA);

        val = ioread32(nhi->iobase + REG_INMAIL_CMD);
        val &= ~(REG_INMAIL_CMD_MASK | REG_INMAIL_ERROR);
        val |= REG_INMAIL_OP_REQUEST | cmd;
        iowrite32(val, nhi->iobase + REG_INMAIL_CMD);

        timeout = ktime_add_ms(ktime_get(), NHI_MAILBOX_TIMEOUT);
        do {
                val = ioread32(nhi->iobase + REG_INMAIL_CMD);
                if (!(val & REG_INMAIL_OP_REQUEST))
                        break;
                usleep_range(10, 20);
        } while (ktime_before(ktime_get(), timeout));

        if (val & REG_INMAIL_OP_REQUEST)
                return -ETIMEDOUT;
        if (val & REG_INMAIL_ERROR)
                return -EIO;

        return 0;
}

/**
 * nhi_mailbox_mode() - Return current firmware operation mode
 * @nhi: Pointer to the NHI structure
 *
 * The function reads current firmware operation mode using NHI mailbox
 * registers and returns it to the caller.
 */
enum nhi_fw_mode nhi_mailbox_mode(struct tb_nhi *nhi)
{
        u32 val;

        val = ioread32(nhi->iobase + REG_OUTMAIL_CMD);
        val &= REG_OUTMAIL_CMD_OPMODE_MASK;
        val >>= REG_OUTMAIL_CMD_OPMODE_SHIFT;

        return (enum nhi_fw_mode)val;
}

static void nhi_interrupt_work(struct work_struct *work)
{
        struct tb_nhi *nhi = container_of(work, typeof(*nhi), interrupt_work);
        int value = 0; /* Suppress uninitialized usage warning. */
        int bit;
        int hop = -1;
        int type = 0; /* current interrupt type 0: TX, 1: RX, 2: RX overflow */
        struct tb_ring *ring;

        spin_lock_irq(&nhi->lock);

        /*
         * Starting at REG_RING_NOTIFY_BASE there are three status bitfields
         * (TX, RX, RX overflow). We iterate over the bits and read a new
         * dwords as required. The registers are cleared on read.
         */
        for (bit = 0; bit < 3 * nhi->hop_count; bit++) {
                if (bit % 32 == 0)
                        value = ioread32(nhi->iobase
                                         + REG_RING_NOTIFY_BASE
                                         + 4 * (bit / 32));
                if (++hop == nhi->hop_count) {
                        hop = 0;
                        type++;
                }
                if ((value & (1 << (bit % 32))) == 0)
                        continue;
                if (type == 2) {
                        dev_warn(&nhi->pdev->dev,
                                 "RX overflow for ring %d\n",
                                 hop);
                        continue;
                }
                if (type == 0)
                        ring = nhi->tx_rings[hop];
                else
                        ring = nhi->rx_rings[hop];
                if (ring == NULL) {
                        dev_warn(&nhi->pdev->dev,
                                 "got interrupt for inactive %s ring %d\n",
                                 type ? "RX" : "TX",
                                 hop);
                        continue;
                }

                spin_lock(&ring->lock);
                __ring_interrupt(ring);
                spin_unlock(&ring->lock);
        }
        spin_unlock_irq(&nhi->lock);
}

static irqreturn_t nhi_msi(int irq, void *data)
{
        struct tb_nhi *nhi = data;
        schedule_work(&nhi->interrupt_work);
        return IRQ_HANDLED;
}

static int __nhi_suspend_noirq(struct device *dev, bool wakeup)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);
        struct tb_nhi *nhi = tb->nhi;
        int ret;

        ret = tb_domain_suspend_noirq(tb);
        if (ret)
                return ret;

        if (nhi->ops && nhi->ops->suspend_noirq) {
                ret = nhi->ops->suspend_noirq(tb->nhi, wakeup);
                if (ret)
                        return ret;
        }

        return 0;
}

static int nhi_suspend_noirq(struct device *dev)
{
        return __nhi_suspend_noirq(dev, device_may_wakeup(dev));
}

static int nhi_freeze_noirq(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);

        return tb_domain_freeze_noirq(tb);
}

static int nhi_thaw_noirq(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);

        return tb_domain_thaw_noirq(tb);
}

static bool nhi_wake_supported(struct pci_dev *pdev)
{
        u8 val;

        /*
         * If power rails are sustainable for wakeup from S4 this
         * property is set by the BIOS.
         */
        if (device_property_read_u8(&pdev->dev, "WAKE_SUPPORTED", &val))
                return !!val;

        return true;
}

static int nhi_poweroff_noirq(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        bool wakeup;

        wakeup = device_may_wakeup(dev) && nhi_wake_supported(pdev);
        return __nhi_suspend_noirq(dev, wakeup);
}

static void nhi_enable_int_throttling(struct tb_nhi *nhi)
{
        /* Throttling is specified in 256ns increments */
        u32 throttle = DIV_ROUND_UP(128 * NSEC_PER_USEC, 256);
        unsigned int i;

        /*
         * Configure interrupt throttling for all vectors even if we
         * only use few.
         */
        for (i = 0; i < MSIX_MAX_VECS; i++) {
                u32 reg = REG_INT_THROTTLING_RATE + i * 4;
                iowrite32(throttle, nhi->iobase + reg);
        }
}

static int nhi_resume_noirq(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);
        struct tb_nhi *nhi = tb->nhi;
        int ret;

        /*
         * Check that the device is still there. It may be that the user
         * unplugged last device which causes the host controller to go
         * away on PCs.
         */
        if (!pci_device_is_present(pdev)) {
                nhi->going_away = true;
        } else {
                if (nhi->ops && nhi->ops->resume_noirq) {
                        ret = nhi->ops->resume_noirq(nhi);
                        if (ret)
                                return ret;
                }
                nhi_enable_int_throttling(tb->nhi);

        }

        return tb_domain_resume_noirq(tb);
}

static int nhi_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);

        return tb_domain_suspend(tb);
}

static void nhi_complete(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);

        /*
         * If we were runtime suspended when system suspend started,
         * schedule runtime resume now. It should bring the domain back
         * to functional state.
         */
        if (pm_runtime_suspended(&pdev->dev))
                pm_runtime_resume(&pdev->dev);
        else
                tb_domain_complete(tb);
}

static int nhi_runtime_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);
        struct tb_nhi *nhi = tb->nhi;
        int ret;

        ret = tb_domain_runtime_suspend(tb);
        if (ret)
                return ret;

        if (nhi->ops && nhi->ops->runtime_suspend) {
                ret = nhi->ops->runtime_suspend(tb->nhi);
                if (ret)
                        return ret;
        }
        return 0;
}

static int nhi_runtime_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);
        struct tb_nhi *nhi = tb->nhi;
        int ret;

        if (nhi->ops && nhi->ops->runtime_resume) {
                ret = nhi->ops->runtime_resume(nhi);
                if (ret)
                        return ret;
        }

        nhi_enable_int_throttling(nhi);
        return tb_domain_runtime_resume(tb);
}

static void nhi_shutdown(struct tb_nhi *nhi)
{
        int i;

        dev_dbg(&nhi->pdev->dev, "shutdown\n");

        for (i = 0; i < nhi->hop_count; i++) {
                if (nhi->tx_rings[i])
                        dev_WARN(&nhi->pdev->dev,
                                 "TX ring %d is still active\n", i);
                if (nhi->rx_rings[i])
                        dev_WARN(&nhi->pdev->dev,
                                 "RX ring %d is still active\n", i);
        }
        nhi_disable_interrupts(nhi);
        /*
         * We have to release the irq before calling flush_work. Otherwise an
         * already executing IRQ handler could call schedule_work again.
         */
        if (!nhi->pdev->msix_enabled) {
                devm_free_irq(&nhi->pdev->dev, nhi->pdev->irq, nhi);
                flush_work(&nhi->interrupt_work);
        }
        ida_destroy(&nhi->msix_ida);

        if (nhi->ops && nhi->ops->shutdown)
                nhi->ops->shutdown(nhi);
}

static void nhi_check_quirks(struct tb_nhi *nhi)
{
        /*
         * Intel hardware supports auto clear of the interrupt status
         * reqister right after interrupt is being issued.
         */
        if (nhi->pdev->vendor == PCI_VENDOR_ID_INTEL)
                nhi->quirks |= QUIRK_AUTO_CLEAR_INT;
}

static int nhi_init_msi(struct tb_nhi *nhi)
{
        struct pci_dev *pdev = nhi->pdev;
        int res, irq, nvec;

        /* In case someone left them on. */
        nhi_disable_interrupts(nhi);

        nhi_enable_int_throttling(nhi);

        ida_init(&nhi->msix_ida);

        /*
         * The NHI has 16 MSI-X vectors or a single MSI. We first try to
         * get all MSI-X vectors and if we succeed, each ring will have
         * one MSI-X. If for some reason that does not work out, we
         * fallback to a single MSI.
         */
        nvec = pci_alloc_irq_vectors(pdev, MSIX_MIN_VECS, MSIX_MAX_VECS,
                                     PCI_IRQ_MSIX);
        if (nvec < 0) {
                nvec = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
                if (nvec < 0)
                        return nvec;

                INIT_WORK(&nhi->interrupt_work, nhi_interrupt_work);

                irq = pci_irq_vector(nhi->pdev, 0);
                if (irq < 0)
                        return irq;

                res = devm_request_irq(&pdev->dev, irq, nhi_msi,
                                       IRQF_NO_SUSPEND, "thunderbolt", nhi);
                if (res) {
                        dev_err(&pdev->dev, "request_irq failed, aborting\n");
                        return res;
                }
        }

        return 0;
}

static bool nhi_imr_valid(struct pci_dev *pdev)
{
        u8 val;

        if (!device_property_read_u8(&pdev->dev, "IMR_VALID", &val))
                return !!val;

        return true;
}

static struct tb *nhi_select_cm(struct tb_nhi *nhi)
{
        struct tb *tb;

        /*
         * USB4 case is simple. If we got control of any of the
         * capabilities, we use software CM.
         */
        if (tb_acpi_is_native())
                return tb_probe(nhi);

        /*
         * Either firmware based CM is running (we did not get control
         * from the firmware) or this is pre-USB4 PC so try first
         * firmware CM and then fallback to software CM.
         */
        tb = icm_probe(nhi);
        if (!tb)
                tb = tb_probe(nhi);

        return tb;
}

static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        struct tb_nhi *nhi;
        struct tb *tb;
        int res;

        if (!nhi_imr_valid(pdev)) {
                dev_warn(&pdev->dev, "firmware image not valid, aborting\n");
                return -ENODEV;
        }

        res = pcim_enable_device(pdev);
        if (res) {
                dev_err(&pdev->dev, "cannot enable PCI device, aborting\n");
                return res;
        }

        res = pcim_iomap_regions(pdev, 1 << 0, "thunderbolt");
        if (res) {
                dev_err(&pdev->dev, "cannot obtain PCI resources, aborting\n");
                return res;
        }

        nhi = devm_kzalloc(&pdev->dev, sizeof(*nhi), GFP_KERNEL);
        if (!nhi)
                return -ENOMEM;

        nhi->pdev = pdev;
        nhi->ops = (const struct tb_nhi_ops *)id->driver_data;
        /* cannot fail - table is allocated bin pcim_iomap_regions */
        nhi->iobase = pcim_iomap_table(pdev)[0];
        nhi->hop_count = ioread32(nhi->iobase + REG_HOP_COUNT) & 0x3ff;
        dev_dbg(&pdev->dev, "total paths: %d\n", nhi->hop_count);

        nhi->tx_rings = devm_kcalloc(&pdev->dev, nhi->hop_count,
                                     sizeof(*nhi->tx_rings), GFP_KERNEL);
        nhi->rx_rings = devm_kcalloc(&pdev->dev, nhi->hop_count,
                                     sizeof(*nhi->rx_rings), GFP_KERNEL);
        if (!nhi->tx_rings || !nhi->rx_rings)
                return -ENOMEM;

        nhi_check_quirks(nhi);

        res = nhi_init_msi(nhi);
        if (res) {
                dev_err(&pdev->dev, "cannot enable MSI, aborting\n");
                return res;
        }

        spin_lock_init(&nhi->lock);

        res = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
        if (res)
                res = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
        if (res) {
                dev_err(&pdev->dev, "failed to set DMA mask\n");
                return res;
        }

        pci_set_master(pdev);

        if (nhi->ops && nhi->ops->init) {
                res = nhi->ops->init(nhi);
                if (res)
                        return res;
        }

        tb = nhi_select_cm(nhi);
        if (!tb) {
                dev_err(&nhi->pdev->dev,
                        "failed to determine connection manager, aborting\n");
                return -ENODEV;
        }

        dev_dbg(&nhi->pdev->dev, "NHI initialized, starting thunderbolt\n");

        res = tb_domain_add(tb);
        if (res) {
                /*
                 * At this point the RX/TX rings might already have been
                 * activated. Do a proper shutdown.
                 */
                tb_domain_put(tb);
                nhi_shutdown(nhi);
                return res;
        }
        pci_set_drvdata(pdev, tb);

        device_wakeup_enable(&pdev->dev);

        pm_runtime_allow(&pdev->dev);
        pm_runtime_set_autosuspend_delay(&pdev->dev, TB_AUTOSUSPEND_DELAY);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_put_autosuspend(&pdev->dev);

        return 0;
}

static void nhi_remove(struct pci_dev *pdev)
{
        struct tb *tb = pci_get_drvdata(pdev);
        struct tb_nhi *nhi = tb->nhi;

        pm_runtime_get_sync(&pdev->dev);
        pm_runtime_dont_use_autosuspend(&pdev->dev);
        pm_runtime_forbid(&pdev->dev);

        tb_domain_remove(tb);
        nhi_shutdown(nhi);
}

/*
 * The tunneled pci bridges are siblings of us. Use resume_noirq to reenable
 * the tunnels asap. A corresponding pci quirk blocks the downstream bridges
 * resume_noirq until we are done.
 */
static const struct dev_pm_ops nhi_pm_ops = {
        .suspend_noirq = nhi_suspend_noirq,
        .resume_noirq = nhi_resume_noirq,
        .freeze_noirq = nhi_freeze_noirq,  /*
                                            * we just disable hotplug, the
                                            * pci-tunnels stay alive.
                                            */
        .thaw_noirq = nhi_thaw_noirq,
        .restore_noirq = nhi_resume_noirq,
        .suspend = nhi_suspend,
        .poweroff_noirq = nhi_poweroff_noirq,
        .poweroff = nhi_suspend,
        .complete = nhi_complete,
        .runtime_suspend = nhi_runtime_suspend,
        .runtime_resume = nhi_runtime_resume,
};

static struct pci_device_id nhi_ids[] = {
        /*
         * We have to specify class, the TB bridges use the same device and
         * vendor (sub)id on gen 1 and gen 2 controllers.
         */
        {
                .class = PCI_CLASS_SYSTEM_OTHER << 8, .class_mask = ~0,
                .vendor = PCI_VENDOR_ID_INTEL,
                .device = PCI_DEVICE_ID_INTEL_LIGHT_RIDGE,
                .subvendor = 0x2222, .subdevice = 0x1111,
        },
        {
                .class = PCI_CLASS_SYSTEM_OTHER << 8, .class_mask = ~0,
                .vendor = PCI_VENDOR_ID_INTEL,
                .device = PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C,
                .subvendor = 0x2222, .subdevice = 0x1111,
        },
        {
                .class = PCI_CLASS_SYSTEM_OTHER << 8, .class_mask = ~0,
                .vendor = PCI_VENDOR_ID_INTEL,
                .device = PCI_DEVICE_ID_INTEL_FALCON_RIDGE_2C_NHI,
                .subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID,
        },
        {
                .class = PCI_CLASS_SYSTEM_OTHER << 8, .class_mask = ~0,
                .vendor = PCI_VENDOR_ID_INTEL,
                .device = PCI_DEVICE_ID_INTEL_FALCON_RIDGE_4C_NHI,
                .subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID,
        },

        /* Thunderbolt 3 */
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_2C_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_4C_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_USBONLY_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_LP_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_LP_USBONLY_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_C_2C_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_C_4C_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_C_USBONLY_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_TITAN_RIDGE_2C_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_TITAN_RIDGE_4C_NHI) },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ICL_NHI0),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ICL_NHI1),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_TGL_NHI0),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_TGL_NHI1),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_TGL_H_NHI0),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_TGL_H_NHI1),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ADL_NHI0),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ADL_NHI1),
          .driver_data = (kernel_ulong_t)&icl_nhi_ops },

        /* Any USB4 compliant host */
        { PCI_DEVICE_CLASS(PCI_CLASS_SERIAL_USB_USB4, ~0) },

        { 0,}
};

MODULE_DEVICE_TABLE(pci, nhi_ids);
MODULE_LICENSE("GPL");

static struct pci_driver nhi_driver = {
        .name = "thunderbolt",
        .id_table = nhi_ids,
        .probe = nhi_probe,
        .remove = nhi_remove,
        .shutdown = nhi_remove,
        .driver.pm = &nhi_pm_ops,
};

static int __init nhi_init(void)
{
        int ret;

        ret = tb_domain_init();
        if (ret)
                return ret;
        ret = pci_register_driver(&nhi_driver);
        if (ret)
                tb_domain_exit();
        return ret;
}

static void __exit nhi_unload(void)
{
        pci_unregister_driver(&nhi_driver);
        tb_domain_exit();
}

rootfs_initcall(nhi_init);
module_exit(nhi_unload);