/*
 * Thunderbolt Cactus Ridge 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>
 */

#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/dmi.h>

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

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


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;
        int bit = ring_interrupt_index(ring) & 31;
        int mask = 1 << bit;
        u32 old, new;
        old = ioread32(ring->nhi->iobase + reg);
        if (active)
                new = old | mask;
        else
                new = old & ~mask;

        dev_info(&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_iowrite16desc(struct tb_ring *ring, u32 value, u32 offset)
{
        iowrite16(value, ring_desc_base(ring) + offset);
}

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;
                ring_iowrite16desc(ring, ring->head, ring->is_tx ? 10 : 8);
        }
}

/**
 * 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;
        LIST_HEAD(done);
        mutex_lock(&ring->lock);

        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;
                        if (frame->sof != 0)
                                dev_WARN(&ring->nhi->pdev->dev,
                                         "%s %d got unexpected SOF: %#x\n",
                                         RING_TYPE(ring), ring->hop,
                                         frame->sof);
                        /*
                         * known flags:
                         * raw not enabled, interupt not set: 0x2=0010
                         * raw enabled: 0xa=1010
                         * raw not enabled: 0xb=1011
                         * partial frame (>MAX_FRAME_SIZE): 0xe=1110
                         */
                        if (frame->flags != 0xa)
                                dev_WARN(&ring->nhi->pdev->dev,
                                         "%s %d got unexpected flags: %#x\n",
                                         RING_TYPE(ring), ring->hop,
                                         frame->flags);
                }
                ring->tail = (ring->tail + 1) % ring->size;
        }
        ring_write_descriptors(ring);

invoke_callback:
        mutex_unlock(&ring->lock); /* allow callbacks to schedule new work */
        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);
                frame->callback(ring, frame, canceled);
        }
}

int __ring_enqueue(struct tb_ring *ring, struct ring_frame *frame)
{
        int ret = 0;
        mutex_lock(&ring->lock);
        if (ring->running) {
                list_add_tail(&frame->list, &ring->queue);
                ring_write_descriptors(ring);
        } else {
                ret = -ESHUTDOWN;
        }
        mutex_unlock(&ring->lock);
        return ret;
}

static struct tb_ring *ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
                                  bool transmit)
{
        struct tb_ring *ring = NULL;
        dev_info(&nhi->pdev->dev, "allocating %s ring %d of size %d\n",
                 transmit ? "TX" : "RX", hop, size);

        mutex_lock(&nhi->lock);
        if (hop >= nhi->hop_count) {
                dev_WARN(&nhi->pdev->dev, "invalid hop: %d\n", hop);
                goto err;
        }
        if (transmit && nhi->tx_rings[hop]) {
                dev_WARN(&nhi->pdev->dev, "TX hop %d already allocated\n", hop);
                goto err;
        } else if (!transmit && nhi->rx_rings[hop]) {
                dev_WARN(&nhi->pdev->dev, "RX hop %d already allocated\n", hop);
                goto err;
        }
        ring = kzalloc(sizeof(*ring), GFP_KERNEL);
        if (!ring)
                goto err;

        mutex_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->head = 0;
        ring->tail = 0;
        ring->running = false;
        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;

        if (transmit)
                nhi->tx_rings[hop] = ring;
        else
                nhi->rx_rings[hop] = ring;
        mutex_unlock(&nhi->lock);
        return ring;

err:
        if (ring)
                mutex_destroy(&ring->lock);
        kfree(ring);
        mutex_unlock(&nhi->lock);
        return NULL;
}

struct tb_ring *ring_alloc_tx(struct tb_nhi *nhi, int hop, int size)
{
        return ring_alloc(nhi, hop, size, true);
}

struct tb_ring *ring_alloc_rx(struct tb_nhi *nhi, int hop, int size)
{
        return ring_alloc(nhi, hop, size, false);
}

/**
 * ring_start() - enable a ring
 *
 * Must not be invoked in parallel with ring_stop().
 */
void ring_start(struct tb_ring *ring)
{
        mutex_lock(&ring->nhi->lock);
        mutex_lock(&ring->lock);
        if (ring->running) {
                dev_WARN(&ring->nhi->pdev->dev, "ring already started\n");
                goto err;
        }
        dev_info(&ring->nhi->pdev->dev, "starting %s %d\n",
                 RING_TYPE(ring), ring->hop);

        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,
                                      RING_FLAG_ENABLE | RING_FLAG_RAW, 0);
        } else {
                ring_iowrite32desc(ring,
                                   (TB_FRAME_SIZE << 16) | ring->size, 12);
                ring_iowrite32options(ring, 0xffffffff, 4); /* SOF EOF mask */
                ring_iowrite32options(ring,
                                      RING_FLAG_ENABLE | RING_FLAG_RAW, 0);
        }
        ring_interrupt_active(ring, true);
        ring->running = true;
err:
        mutex_unlock(&ring->lock);
        mutex_unlock(&ring->nhi->lock);
}


/**
 * ring_stop() - shutdown a ring
 *
 * Must not be invoked from a callback.
 *
 * This method will disable the ring. Further calls to ring_tx/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 ring_stop(struct tb_ring *ring)
{
        mutex_lock(&ring->nhi->lock);
        mutex_lock(&ring->lock);
        dev_info(&ring->nhi->pdev->dev, "stopping %s %d\n",
                 RING_TYPE(ring), ring->hop);
        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_iowrite16desc(ring, 0, ring->is_tx ? 10 : 8);
        ring_iowrite32desc(ring, 0, 12);
        ring->head = 0;
        ring->tail = 0;
        ring->running = false;

err:
        mutex_unlock(&ring->lock);
        mutex_unlock(&ring->nhi->lock);

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

/*
 * 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 ring_free(struct tb_ring *ring)
{
        mutex_lock(&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);
        }

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

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

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;

        mutex_lock(&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;
                }
                /* we do not check ring->running, this is done in ring->work */
                schedule_work(&ring->work);
        }
        mutex_unlock(&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)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);
        thunderbolt_suspend(tb);
        return 0;
}

static int nhi_resume_noirq(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct tb *tb = pci_get_drvdata(pdev);
        thunderbolt_resume(tb);
        return 0;
}

static void nhi_shutdown(struct tb_nhi *nhi)
{
        int i;
        dev_info(&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.
         */
        devm_free_irq(&nhi->pdev->dev, nhi->pdev->irq, nhi);
        flush_work(&nhi->interrupt_work);
        mutex_destroy(&nhi->lock);
}

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

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

        res = pci_enable_msi(pdev);
        if (res) {
                dev_err(&pdev->dev, "cannot enable MSI, 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;
        /* 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;
        if (nhi->hop_count != 12)
                dev_warn(&pdev->dev, "unexpected hop count: %d\n",
                         nhi->hop_count);
        INIT_WORK(&nhi->interrupt_work, nhi_interrupt_work);

        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_disable_interrupts(nhi); /* In case someone left them on. */
        res = devm_request_irq(&pdev->dev, pdev->irq, nhi_msi,
                               IRQF_NO_SUSPEND, /* must work during _noirq */
                               "thunderbolt", nhi);
        if (res) {
                dev_err(&pdev->dev, "request_irq failed, aborting\n");
                return res;
        }

        mutex_init(&nhi->lock);

        pci_set_master(pdev);

        /* magic value - clock related? */
        iowrite32(3906250 / 10000, nhi->iobase + 0x38c00);

        dev_info(&nhi->pdev->dev, "NHI initialized, starting thunderbolt\n");
        tb = thunderbolt_alloc_and_start(nhi);
        if (!tb) {
                /*
                 * At this point the RX/TX rings might already have been
                 * activated. Do a proper shutdown.
                 */
                nhi_shutdown(nhi);
                return -EIO;
        }
        pci_set_drvdata(pdev, tb);

        return 0;
}

static void nhi_remove(struct pci_dev *pdev)
{
        struct tb *tb = pci_get_drvdata(pdev);
        struct tb_nhi *nhi = tb->nhi;
        thunderbolt_shutdown_and_free(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_suspend_noirq, /*
                                            * we just disable hotplug, the
                                            * pci-tunnels stay alive.
                                            */
        .restore_noirq = nhi_resume_noirq,
};

static struct pci_device_id nhi_ids[] = {
        /*
         * We have to specify class, the TB bridges use the same device and
         * vendor (sub)id.
         */
        {
                .class = PCI_CLASS_SYSTEM_OTHER << 8, .class_mask = ~0,
                .vendor = PCI_VENDOR_ID_INTEL, .device = 0x1547,
                .subvendor = 0x2222, .subdevice = 0x1111,
        },
        {
                .class = PCI_CLASS_SYSTEM_OTHER << 8, .class_mask = ~0,
                .vendor = PCI_VENDOR_ID_INTEL, .device = 0x156c,
                .subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID,
        },
        { 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,
        .driver.pm = &nhi_pm_ops,
};

static int __init nhi_init(void)
{
        if (!dmi_match(DMI_BOARD_VENDOR, "Apple Inc."))
                return -ENOSYS;
        return pci_register_driver(&nhi_driver);
}

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

module_init(nhi_init);
module_exit(nhi_unload);