/* Copyright 2009 - 2016 Freescale Semiconductor, Inc.
 *
 * 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 Freescale Semiconductor nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * ALTERNATIVELY, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") as published by the Free Software
 * Foundation, either version 2 of that License or (at your option) any
 * later version.
 *
 * THIS SOFTWARE IS PROVIDED BY Freescale Semiconductor ``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 Freescale Semiconductor 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 "qman_test.h"

#include <linux/dma-mapping.h>
#include <linux/delay.h>

/*
 * Algorithm:
 *
 * Each cpu will have HP_PER_CPU "handlers" set up, each of which incorporates
 * an rx/tx pair of FQ objects (both of which are stashed on dequeue). The
 * organisation of FQIDs is such that the HP_PER_CPU*NUM_CPUS handlers will
 * shuttle a "hot potato" frame around them such that every forwarding action
 * moves it from one cpu to another. (The use of more than one handler per cpu
 * is to allow enough handlers/FQs to truly test the significance of caching -
 * ie. when cache-expiries are occurring.)
 *
 * The "hot potato" frame content will be HP_NUM_WORDS*4 bytes in size, and the
 * first and last words of the frame data will undergo a transformation step on
 * each forwarding action. To achieve this, each handler will be assigned a
 * 32-bit "mixer", that is produced using a 32-bit LFSR. When a frame is
 * received by a handler, the mixer of the expected sender is XOR'd into all
 * words of the entire frame, which is then validated against the original
 * values. Then, before forwarding, the entire frame is XOR'd with the mixer of
 * the current handler. Apart from validating that the frame is taking the
 * expected path, this also provides some quasi-realistic overheads to each
 * forwarding action - dereferencing *all* the frame data, computation, and
 * conditional branching. There is a "special" handler designated to act as the
 * instigator of the test by creating an enqueuing the "hot potato" frame, and
 * to determine when the test has completed by counting HP_LOOPS iterations.
 *
 * Init phases:
 *
 * 1. prepare each cpu's 'hp_cpu' struct using on_each_cpu(,,1) and link them
 *    into 'hp_cpu_list'. Specifically, set processor_id, allocate HP_PER_CPU
 *    handlers and link-list them (but do no other handler setup).
 *
 * 2. scan over 'hp_cpu_list' HP_PER_CPU times, the first time sets each
 *    hp_cpu's 'iterator' to point to its first handler. With each loop,
 *    allocate rx/tx FQIDs and mixer values to the hp_cpu's iterator handler
 *    and advance the iterator for the next loop. This includes a final fixup,
 *    which connects the last handler to the first (and which is why phase 2
 *    and 3 are separate).
 *
 * 3. scan over 'hp_cpu_list' HP_PER_CPU times, the first time sets each
 *    hp_cpu's 'iterator' to point to its first handler. With each loop,
 *    initialise FQ objects and advance the iterator for the next loop.
 *    Moreover, do this initialisation on the cpu it applies to so that Rx FQ
 *    initialisation targets the correct cpu.
 */

/*
 * helper to run something on all cpus (can't use on_each_cpu(), as that invokes
 * the fn from irq context, which is too restrictive).
 */
struct bstrap {
        int (*fn)(void);
        atomic_t started;
};
static int bstrap_fn(void *bs)
{
        struct bstrap *bstrap = bs;
        int err;

        atomic_inc(&bstrap->started);
        err = bstrap->fn();
        if (err)
                return err;
        while (!kthread_should_stop())
                msleep(20);
        return 0;
}
static int on_all_cpus(int (*fn)(void))
{
        int cpu;

        for_each_online_cpu(cpu) {
                struct bstrap bstrap = {
                        .fn = fn,
                        .started = ATOMIC_INIT(0)
                };
                struct task_struct *k = kthread_run_on_cpu(bstrap_fn, &bstrap,
                                                           cpu, "hotpotato%d");
                int ret;

                if (IS_ERR(k))
                        return -ENOMEM;
                /*
                 * If we call kthread_stop() before the "wake up" has had an
                 * effect, then the thread may exit with -EINTR without ever
                 * running the function. So poll until it's started before
                 * requesting it to stop.
                 */
                while (!atomic_read(&bstrap.started))
                        msleep(20);
                ret = kthread_stop(k);
                if (ret)
                        return ret;
        }
        return 0;
}

struct hp_handler {

        /* The following data is stashed when 'rx' is dequeued; */
        /* -------------- */
        /* The Rx FQ, dequeues of which will stash the entire hp_handler */
        struct qman_fq rx;
        /* The Tx FQ we should forward to */
        struct qman_fq tx;
        /* The value we XOR post-dequeue, prior to validating */
        u32 rx_mixer;
        /* The value we XOR pre-enqueue, after validating */
        u32 tx_mixer;
        /* what the hotpotato address should be on dequeue */
        dma_addr_t addr;
        u32 *frame_ptr;

        /* The following data isn't (necessarily) stashed on dequeue; */
        /* -------------- */
        u32 fqid_rx, fqid_tx;
        /* list node for linking us into 'hp_cpu' */
        struct list_head node;
        /* Just to check ... */
        unsigned int processor_id;
} ____cacheline_aligned;

struct hp_cpu {
        /* identify the cpu we run on; */
        unsigned int processor_id;
        /* root node for the per-cpu list of handlers */
        struct list_head handlers;
        /* list node for linking us into 'hp_cpu_list' */
        struct list_head node;
        /*
         * when repeatedly scanning 'hp_list', each time linking the n'th
         * handlers together, this is used as per-cpu iterator state
         */
        struct hp_handler *iterator;
};

/* Each cpu has one of these */
static DEFINE_PER_CPU(struct hp_cpu, hp_cpus);

/* links together the hp_cpu structs, in first-come first-serve order. */
static LIST_HEAD(hp_cpu_list);
static DEFINE_SPINLOCK(hp_lock);

static unsigned int hp_cpu_list_length;

/* the "special" handler, that starts and terminates the test. */
static struct hp_handler *special_handler;
static int loop_counter;

/* handlers are allocated out of this, so they're properly aligned. */
static struct kmem_cache *hp_handler_slab;

/* this is the frame data */
static void *__frame_ptr;
static u32 *frame_ptr;
static dma_addr_t frame_dma;

/* needed for dma_map*() */
static const struct qm_portal_config *pcfg;

/* the main function waits on this */
static DECLARE_WAIT_QUEUE_HEAD(queue);

#define HP_PER_CPU      2
#define HP_LOOPS        8
/* 80 bytes, like a small ethernet frame, and bleeds into a second cacheline */
#define HP_NUM_WORDS    80
/* First word of the LFSR-based frame data */
#define HP_FIRST_WORD   0xabbaf00d

static inline u32 do_lfsr(u32 prev)
{
        return (prev >> 1) ^ (-(prev & 1u) & 0xd0000001u);
}

static int allocate_frame_data(void)
{
        u32 lfsr = HP_FIRST_WORD;
        int loop;

        if (!qman_dma_portal) {
                pr_crit("portal not available\n");
                return -EIO;
        }

        pcfg = qman_get_qm_portal_config(qman_dma_portal);

        __frame_ptr = kmalloc_array(4, HP_NUM_WORDS, GFP_KERNEL);
        if (!__frame_ptr)
                return -ENOMEM;

        frame_ptr = PTR_ALIGN(__frame_ptr, 64);
        for (loop = 0; loop < HP_NUM_WORDS; loop++) {
                frame_ptr[loop] = lfsr;
                lfsr = do_lfsr(lfsr);
        }

        frame_dma = dma_map_single(pcfg->dev, frame_ptr, 4 * HP_NUM_WORDS,
                                   DMA_BIDIRECTIONAL);
        if (dma_mapping_error(pcfg->dev, frame_dma)) {
                pr_crit("dma mapping failure\n");
                kfree(__frame_ptr);
                return -EIO;
        }

        return 0;
}

static void deallocate_frame_data(void)
{
        dma_unmap_single(pcfg->dev, frame_dma, 4 * HP_NUM_WORDS,
                         DMA_BIDIRECTIONAL);
        kfree(__frame_ptr);
}

static inline int process_frame_data(struct hp_handler *handler,
                                     const struct qm_fd *fd)
{
        u32 *p = handler->frame_ptr;
        u32 lfsr = HP_FIRST_WORD;
        int loop;

        if (qm_fd_addr_get64(fd) != handler->addr) {
                pr_crit("bad frame address, [%llX != %llX]\n",
                        qm_fd_addr_get64(fd), handler->addr);
                return -EIO;
        }
        for (loop = 0; loop < HP_NUM_WORDS; loop++, p++) {
                *p ^= handler->rx_mixer;
                if (*p != lfsr) {
                        pr_crit("corrupt frame data");
                        return -EIO;
                }
                *p ^= handler->tx_mixer;
                lfsr = do_lfsr(lfsr);
        }
        return 0;
}

static enum qman_cb_dqrr_result normal_dqrr(struct qman_portal *portal,
                                            struct qman_fq *fq,
                                            const struct qm_dqrr_entry *dqrr,
                                            bool sched_napi)
{
        struct hp_handler *handler = (struct hp_handler *)fq;

        if (process_frame_data(handler, &dqrr->fd)) {
                WARN_ON(1);
                goto skip;
        }
        if (qman_enqueue(&handler->tx, &dqrr->fd)) {
                pr_crit("qman_enqueue() failed");
                WARN_ON(1);
        }
skip:
        return qman_cb_dqrr_consume;
}

static enum qman_cb_dqrr_result special_dqrr(struct qman_portal *portal,
                                             struct qman_fq *fq,
                                             const struct qm_dqrr_entry *dqrr,
                                             bool sched_napi)
{
        struct hp_handler *handler = (struct hp_handler *)fq;

        process_frame_data(handler, &dqrr->fd);
        if (++loop_counter < HP_LOOPS) {
                if (qman_enqueue(&handler->tx, &dqrr->fd)) {
                        pr_crit("qman_enqueue() failed");
                        WARN_ON(1);
                        goto skip;
                }
        } else {
                pr_info("Received final (%dth) frame\n", loop_counter);
                wake_up(&queue);
        }
skip:
        return qman_cb_dqrr_consume;
}

static int create_per_cpu_handlers(void)
{
        struct hp_handler *handler;
        int loop;
        struct hp_cpu *hp_cpu = this_cpu_ptr(&hp_cpus);

        hp_cpu->processor_id = smp_processor_id();
        spin_lock(&hp_lock);
        list_add_tail(&hp_cpu->node, &hp_cpu_list);
        hp_cpu_list_length++;
        spin_unlock(&hp_lock);
        INIT_LIST_HEAD(&hp_cpu->handlers);
        for (loop = 0; loop < HP_PER_CPU; loop++) {
                handler = kmem_cache_alloc(hp_handler_slab, GFP_KERNEL);
                if (!handler) {
                        pr_crit("kmem_cache_alloc() failed");
                        WARN_ON(1);
                        return -EIO;
                }
                handler->processor_id = hp_cpu->processor_id;
                handler->addr = frame_dma;
                handler->frame_ptr = frame_ptr;
                list_add_tail(&handler->node, &hp_cpu->handlers);
        }
        return 0;
}

static int destroy_per_cpu_handlers(void)
{
        struct list_head *loop, *tmp;
        struct hp_cpu *hp_cpu = this_cpu_ptr(&hp_cpus);

        spin_lock(&hp_lock);
        list_del(&hp_cpu->node);
        spin_unlock(&hp_lock);
        list_for_each_safe(loop, tmp, &hp_cpu->handlers) {
                u32 flags = 0;
                struct hp_handler *handler = list_entry(loop, struct hp_handler,
                                                        node);
                if (qman_retire_fq(&handler->rx, &flags) ||
                    (flags & QMAN_FQ_STATE_BLOCKOOS)) {
                        pr_crit("qman_retire_fq(rx) failed, flags: %x", flags);
                        WARN_ON(1);
                        return -EIO;
                }
                if (qman_oos_fq(&handler->rx)) {
                        pr_crit("qman_oos_fq(rx) failed");
                        WARN_ON(1);
                        return -EIO;
                }
                qman_destroy_fq(&handler->rx);
                qman_destroy_fq(&handler->tx);
                qman_release_fqid(handler->fqid_rx);
                list_del(&handler->node);
                kmem_cache_free(hp_handler_slab, handler);
        }
        return 0;
}

static inline u8 num_cachelines(u32 offset)
{
        u8 res = (offset + (L1_CACHE_BYTES - 1))
                         / (L1_CACHE_BYTES);
        if (res > 3)
                return 3;
        return res;
}
#define STASH_DATA_CL \
        num_cachelines(HP_NUM_WORDS * 4)
#define STASH_CTX_CL \
        num_cachelines(offsetof(struct hp_handler, fqid_rx))

static int init_handler(void *h)
{
        struct qm_mcc_initfq opts;
        struct hp_handler *handler = h;
        int err;

        if (handler->processor_id != smp_processor_id()) {
                err = -EIO;
                goto failed;
        }
        /* Set up rx */
        memset(&handler->rx, 0, sizeof(handler->rx));
        if (handler == special_handler)
                handler->rx.cb.dqrr = special_dqrr;
        else
                handler->rx.cb.dqrr = normal_dqrr;
        err = qman_create_fq(handler->fqid_rx, 0, &handler->rx);
        if (err) {
                pr_crit("qman_create_fq(rx) failed");
                goto failed;
        }
        memset(&opts, 0, sizeof(opts));
        opts.we_mask = cpu_to_be16(QM_INITFQ_WE_FQCTRL |
                                   QM_INITFQ_WE_CONTEXTA);
        opts.fqd.fq_ctrl = cpu_to_be16(QM_FQCTRL_CTXASTASHING);
        qm_fqd_set_stashing(&opts.fqd, 0, STASH_DATA_CL, STASH_CTX_CL);
        err = qman_init_fq(&handler->rx, QMAN_INITFQ_FLAG_SCHED |
                           QMAN_INITFQ_FLAG_LOCAL, &opts);
        if (err) {
                pr_crit("qman_init_fq(rx) failed");
                goto failed;
        }
        /* Set up tx */
        memset(&handler->tx, 0, sizeof(handler->tx));
        err = qman_create_fq(handler->fqid_tx, QMAN_FQ_FLAG_NO_MODIFY,
                             &handler->tx);
        if (err) {
                pr_crit("qman_create_fq(tx) failed");
                goto failed;
        }

        return 0;
failed:
        return err;
}

static void init_handler_cb(void *h)
{
        if (init_handler(h))
                WARN_ON(1);
}

static int init_phase2(void)
{
        int loop;
        u32 fqid = 0;
        u32 lfsr = 0xdeadbeef;
        struct hp_cpu *hp_cpu;
        struct hp_handler *handler;

        for (loop = 0; loop < HP_PER_CPU; loop++) {
                list_for_each_entry(hp_cpu, &hp_cpu_list, node) {
                        int err;

                        if (!loop)
                                hp_cpu->iterator = list_first_entry(
                                                &hp_cpu->handlers,
                                                struct hp_handler, node);
                        else
                                hp_cpu->iterator = list_entry(
                                                hp_cpu->iterator->node.next,
                                                struct hp_handler, node);
                        /* Rx FQID is the previous handler's Tx FQID */
                        hp_cpu->iterator->fqid_rx = fqid;
                        /* Allocate new FQID for Tx */
                        err = qman_alloc_fqid(&fqid);
                        if (err) {
                                pr_crit("qman_alloc_fqid() failed");
                                return err;
                        }
                        hp_cpu->iterator->fqid_tx = fqid;
                        /* Rx mixer is the previous handler's Tx mixer */
                        hp_cpu->iterator->rx_mixer = lfsr;
                        /* Get new mixer for Tx */
                        lfsr = do_lfsr(lfsr);
                        hp_cpu->iterator->tx_mixer = lfsr;
                }
        }
        /* Fix up the first handler (fqid_rx==0, rx_mixer=0xdeadbeef) */
        hp_cpu = list_first_entry(&hp_cpu_list, struct hp_cpu, node);
        handler = list_first_entry(&hp_cpu->handlers, struct hp_handler, node);
        if (handler->fqid_rx != 0 || handler->rx_mixer != 0xdeadbeef)
                return 1;
        handler->fqid_rx = fqid;
        handler->rx_mixer = lfsr;
        /* and tag it as our "special" handler */
        special_handler = handler;
        return 0;
}

static int init_phase3(void)
{
        int loop, err;
        struct hp_cpu *hp_cpu;

        for (loop = 0; loop < HP_PER_CPU; loop++) {
                list_for_each_entry(hp_cpu, &hp_cpu_list, node) {
                        if (!loop)
                                hp_cpu->iterator = list_first_entry(
                                                &hp_cpu->handlers,
                                                struct hp_handler, node);
                        else
                                hp_cpu->iterator = list_entry(
                                                hp_cpu->iterator->node.next,
                                                struct hp_handler, node);
                        preempt_disable();
                        if (hp_cpu->processor_id == smp_processor_id()) {
                                err = init_handler(hp_cpu->iterator);
                                if (err)
                                        return err;
                        } else {
                                smp_call_function_single(hp_cpu->processor_id,
                                        init_handler_cb, hp_cpu->iterator, 1);
                        }
                        preempt_enable();
                }
        }
        return 0;
}

static int send_first_frame(void *ignore)
{
        u32 *p = special_handler->frame_ptr;
        u32 lfsr = HP_FIRST_WORD;
        int loop, err;
        struct qm_fd fd;

        if (special_handler->processor_id != smp_processor_id()) {
                err = -EIO;
                goto failed;
        }
        memset(&fd, 0, sizeof(fd));
        qm_fd_addr_set64(&fd, special_handler->addr);
        qm_fd_set_contig_big(&fd, HP_NUM_WORDS * 4);
        for (loop = 0; loop < HP_NUM_WORDS; loop++, p++) {
                if (*p != lfsr) {
                        err = -EIO;
                        pr_crit("corrupt frame data");
                        goto failed;
                }
                *p ^= special_handler->tx_mixer;
                lfsr = do_lfsr(lfsr);
        }
        pr_info("Sending first frame\n");
        err = qman_enqueue(&special_handler->tx, &fd);
        if (err) {
                pr_crit("qman_enqueue() failed");
                goto failed;
        }

        return 0;
failed:
        return err;
}

static void send_first_frame_cb(void *ignore)
{
        if (send_first_frame(NULL))
                WARN_ON(1);
}

int qman_test_stash(void)
{
        int err;

        if (cpumask_weight(cpu_online_mask) < 2) {
                pr_info("%s(): skip - only 1 CPU\n", __func__);
                return 0;
        }

        pr_info("%s(): Starting\n", __func__);

        hp_cpu_list_length = 0;
        loop_counter = 0;
        hp_handler_slab = kmem_cache_create("hp_handler_slab",
                        sizeof(struct hp_handler), L1_CACHE_BYTES,
                        SLAB_HWCACHE_ALIGN, NULL);
        if (!hp_handler_slab) {
                err = -EIO;
                pr_crit("kmem_cache_create() failed");
                goto failed;
        }

        err = allocate_frame_data();
        if (err)
                goto failed;

        /* Init phase 1 */
        pr_info("Creating %d handlers per cpu...\n", HP_PER_CPU);
        if (on_all_cpus(create_per_cpu_handlers)) {
                err = -EIO;
                pr_crit("on_each_cpu() failed");
                goto failed;
        }
        pr_info("Number of cpus: %d, total of %d handlers\n",
                hp_cpu_list_length, hp_cpu_list_length * HP_PER_CPU);

        err = init_phase2();
        if (err)
                goto failed;

        err = init_phase3();
        if (err)
                goto failed;

        preempt_disable();
        if (special_handler->processor_id == smp_processor_id()) {
                err = send_first_frame(NULL);
                if (err)
                        goto failed;
        } else {
                smp_call_function_single(special_handler->processor_id,
                                         send_first_frame_cb, NULL, 1);
        }
        preempt_enable();

        wait_event(queue, loop_counter == HP_LOOPS);
        deallocate_frame_data();
        if (on_all_cpus(destroy_per_cpu_handlers)) {
                err = -EIO;
                pr_crit("on_each_cpu() failed");
                goto failed;
        }
        kmem_cache_destroy(hp_handler_slab);
        pr_info("%s(): Finished\n", __func__);

        return 0;
failed:
        WARN_ON(1);
        return err;
}