/* SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause */
/*
 * Copyright(c) 2015 - 2018 Intel Corporation.
 */

#ifndef _HFI1_IOWAIT_H
#define _HFI1_IOWAIT_H

#include <linux/list.h>
#include <linux/workqueue.h>
#include <linux/wait.h>
#include <linux/sched.h>

#include "sdma_txreq.h"

/*
 * typedef (*restart_t)() - restart callback
 * @work: pointer to work structure
 */
typedef void (*restart_t)(struct work_struct *work);

#define IOWAIT_PENDING_IB  0x0
#define IOWAIT_PENDING_TID 0x1

/*
 * A QP can have multiple Send Engines (SEs).
 *
 * The current use case is for supporting a TID RDMA
 * packet build/xmit mechanism independent from verbs.
 */
#define IOWAIT_SES 2
#define IOWAIT_IB_SE 0
#define IOWAIT_TID_SE 1

struct sdma_txreq;
struct sdma_engine;
/**
 * @iowork: the work struct
 * @tx_head: list of prebuilt packets
 * @iow: the parent iowait structure
 *
 * This structure is the work item (process) specific
 * details associated with the each of the two SEs of the
 * QP.
 *
 * The workstruct and the queued TXs are unique to each
 * SE.
 */
struct iowait;
struct iowait_work {
        struct work_struct iowork;
        struct list_head tx_head;
        struct iowait *iow;
};

/**
 * @list: used to add/insert into QP/PQ wait lists
 * @tx_head: overflow list of sdma_txreq's
 * @sleep: no space callback
 * @wakeup: space callback wakeup
 * @sdma_drained: sdma count drained
 * @init_priority: callback to manipulate priority
 * @lock: lock protected head of wait queue
 * @iowork: workqueue overhead
 * @wait_dma: wait for sdma_busy == 0
 * @wait_pio: wait for pio_busy == 0
 * @sdma_busy: # of packets in flight
 * @count: total number of descriptors in tx_head'ed list
 * @tx_limit: limit for overflow queuing
 * @tx_count: number of tx entry's in tx_head'ed list
 * @flags: wait flags (one per QP)
 * @wait: SE array for multiple legs
 *
 * This is to be embedded in user's state structure
 * (QP or PQ).
 *
 * The sleep and wakeup members are a
 * bit misnamed.   They do not strictly
 * speaking sleep or wake up, but they
 * are callbacks for the ULP to implement
 * what ever queuing/dequeuing of
 * the embedded iowait and its containing struct
 * when a resource shortage like SDMA ring space
 * or PIO credit space is seen.
 *
 * Both potentially have locks help
 * so sleeping is not allowed and it is not
 * supported to submit txreqs from the wakeup
 * call directly because of lock conflicts.
 *
 * The wait_dma member along with the iow
 *
 * The lock field is used by waiters to record
 * the seqlock_t that guards the list head.
 * Waiters explicity know that, but the destroy
 * code that unwaits QPs does not.
 */
struct iowait {
        struct list_head list;
        int (*sleep)(
                struct sdma_engine *sde,
                struct iowait_work *wait,
                struct sdma_txreq *tx,
                uint seq,
                bool pkts_sent
                );
        void (*wakeup)(struct iowait *wait, int reason);
        void (*sdma_drained)(struct iowait *wait);
        void (*init_priority)(struct iowait *wait);
        seqlock_t *lock;
        wait_queue_head_t wait_dma;
        wait_queue_head_t wait_pio;
        atomic_t sdma_busy;
        atomic_t pio_busy;
        u32 count;
        u32 tx_limit;
        u32 tx_count;
        u8 starved_cnt;
        u8 priority;
        unsigned long flags;
        struct iowait_work wait[IOWAIT_SES];
};

#define SDMA_AVAIL_REASON 0

void iowait_set_flag(struct iowait *wait, u32 flag);
bool iowait_flag_set(struct iowait *wait, u32 flag);
void iowait_clear_flag(struct iowait *wait, u32 flag);

void iowait_init(struct iowait *wait, u32 tx_limit,
                 void (*func)(struct work_struct *work),
                 void (*tidfunc)(struct work_struct *work),
                 int (*sleep)(struct sdma_engine *sde,
                              struct iowait_work *wait,
                              struct sdma_txreq *tx,
                              uint seq,
                              bool pkts_sent),
                 void (*wakeup)(struct iowait *wait, int reason),
                 void (*sdma_drained)(struct iowait *wait),
                 void (*init_priority)(struct iowait *wait));

/**
 * iowait_schedule() - schedule the default send engine work
 * @wait: wait struct to schedule
 * @wq: workqueue for schedule
 * @cpu: cpu
 */
static inline bool iowait_schedule(struct iowait *wait,
                                   struct workqueue_struct *wq, int cpu)
{
        return !!queue_work_on(cpu, wq, &wait->wait[IOWAIT_IB_SE].iowork);
}

/**
 * iowait_tid_schedule - schedule the tid SE
 * @wait: the iowait structure
 * @wq: the work queue
 * @cpu: the cpu
 */
static inline bool iowait_tid_schedule(struct iowait *wait,
                                       struct workqueue_struct *wq, int cpu)
{
        return !!queue_work_on(cpu, wq, &wait->wait[IOWAIT_TID_SE].iowork);
}

/**
 * iowait_sdma_drain() - wait for DMAs to drain
 *
 * @wait: iowait structure
 *
 * This will delay until the iowait sdmas have
 * completed.
 */
static inline void iowait_sdma_drain(struct iowait *wait)
{
        wait_event(wait->wait_dma, !atomic_read(&wait->sdma_busy));
}

/**
 * iowait_sdma_pending() - return sdma pending count
 *
 * @wait: iowait structure
 *
 */
static inline int iowait_sdma_pending(struct iowait *wait)
{
        return atomic_read(&wait->sdma_busy);
}

/**
 * iowait_sdma_inc - note sdma io pending
 * @wait: iowait structure
 */
static inline void iowait_sdma_inc(struct iowait *wait)
{
        atomic_inc(&wait->sdma_busy);
}

/**
 * iowait_sdma_add - add count to pending
 * @wait: iowait structure
 */
static inline void iowait_sdma_add(struct iowait *wait, int count)
{
        atomic_add(count, &wait->sdma_busy);
}

/**
 * iowait_sdma_dec - note sdma complete
 * @wait: iowait structure
 */
static inline int iowait_sdma_dec(struct iowait *wait)
{
        if (!wait)
                return 0;
        return atomic_dec_and_test(&wait->sdma_busy);
}

/**
 * iowait_pio_drain() - wait for pios to drain
 *
 * @wait: iowait structure
 *
 * This will delay until the iowait pios have
 * completed.
 */
static inline void iowait_pio_drain(struct iowait *wait)
{
        wait_event_timeout(wait->wait_pio,
                           !atomic_read(&wait->pio_busy),
                           HZ);
}

/**
 * iowait_pio_pending() - return pio pending count
 *
 * @wait: iowait structure
 *
 */
static inline int iowait_pio_pending(struct iowait *wait)
{
        return atomic_read(&wait->pio_busy);
}

/**
 * iowait_pio_inc - note pio pending
 * @wait: iowait structure
 */
static inline void iowait_pio_inc(struct iowait *wait)
{
        atomic_inc(&wait->pio_busy);
}

/**
 * iowait_pio_dec - note pio complete
 * @wait: iowait structure
 */
static inline int iowait_pio_dec(struct iowait *wait)
{
        if (!wait)
                return 0;
        return atomic_dec_and_test(&wait->pio_busy);
}

/**
 * iowait_drain_wakeup() - trigger iowait_drain() waiter
 *
 * @wait: iowait structure
 *
 * This will trigger any waiters.
 */
static inline void iowait_drain_wakeup(struct iowait *wait)
{
        wake_up(&wait->wait_dma);
        wake_up(&wait->wait_pio);
        if (wait->sdma_drained)
                wait->sdma_drained(wait);
}

/**
 * iowait_get_txhead() - get packet off of iowait list
 *
 * @wait: iowait_work structure
 */
static inline struct sdma_txreq *iowait_get_txhead(struct iowait_work *wait)
{
        struct sdma_txreq *tx = NULL;

        if (!list_empty(&wait->tx_head)) {
                tx = list_first_entry(
                        &wait->tx_head,
                        struct sdma_txreq,
                        list);
                list_del_init(&tx->list);
        }
        return tx;
}

static inline u16 iowait_get_desc(struct iowait_work *w)
{
        u16 num_desc = 0;
        struct sdma_txreq *tx = NULL;

        if (!list_empty(&w->tx_head)) {
                tx = list_first_entry(&w->tx_head, struct sdma_txreq,
                                      list);
                num_desc = tx->num_desc;
                if (tx->flags & SDMA_TXREQ_F_VIP)
                        w->iow->priority++;
        }
        return num_desc;
}

static inline u32 iowait_get_all_desc(struct iowait *w)
{
        u32 num_desc = 0;

        num_desc = iowait_get_desc(&w->wait[IOWAIT_IB_SE]);
        num_desc += iowait_get_desc(&w->wait[IOWAIT_TID_SE]);
        return num_desc;
}

static inline void iowait_update_priority(struct iowait_work *w)
{
        struct sdma_txreq *tx = NULL;

        if (!list_empty(&w->tx_head)) {
                tx = list_first_entry(&w->tx_head, struct sdma_txreq,
                                      list);
                if (tx->flags & SDMA_TXREQ_F_VIP)
                        w->iow->priority++;
        }
}

static inline void iowait_update_all_priority(struct iowait *w)
{
        iowait_update_priority(&w->wait[IOWAIT_IB_SE]);
        iowait_update_priority(&w->wait[IOWAIT_TID_SE]);
}

static inline void iowait_init_priority(struct iowait *w)
{
        w->priority = 0;
        if (w->init_priority)
                w->init_priority(w);
}

static inline void iowait_get_priority(struct iowait *w)
{
        iowait_init_priority(w);
        iowait_update_all_priority(w);
}

/**
 * iowait_queue - Put the iowait on a wait queue
 * @pkts_sent: have some packets been sent before queuing?
 * @w: the iowait struct
 * @wait_head: the wait queue
 *
 * This function is called to insert an iowait struct into a
 * wait queue after a resource (eg, sdma descriptor or pio
 * buffer) is run out.
 */
static inline void iowait_queue(bool pkts_sent, struct iowait *w,
                                struct list_head *wait_head)
{
        /*
         * To play fair, insert the iowait at the tail of the wait queue if it
         * has already sent some packets; Otherwise, put it at the head.
         * However, if it has priority packets to send, also put it at the
         * head.
         */
        if (pkts_sent)
                w->starved_cnt = 0;
        else
                w->starved_cnt++;

        if (w->priority > 0 || !pkts_sent)
                list_add(&w->list, wait_head);
        else
                list_add_tail(&w->list, wait_head);
}

/**
 * iowait_starve_clear - clear the wait queue's starve count
 * @pkts_sent: have some packets been sent?
 * @w: the iowait struct
 *
 * This function is called to clear the starve count. If no
 * packets have been sent, the starve count will not be cleared.
 */
static inline void iowait_starve_clear(bool pkts_sent, struct iowait *w)
{
        if (pkts_sent)
                w->starved_cnt = 0;
}

/* Update the top priority index */
uint iowait_priority_update_top(struct iowait *w,
                                struct iowait *top,
                                uint idx, uint top_idx);

/**
 * iowait_packet_queued() - determine if a packet is queued
 * @wait: the iowait_work structure
 */
static inline bool iowait_packet_queued(struct iowait_work *wait)
{
        return !list_empty(&wait->tx_head);
}

/**
 * inc_wait_count - increment wait counts
 * @w: the log work struct
 * @n: the count
 */
static inline void iowait_inc_wait_count(struct iowait_work *w, u16 n)
{
        if (!w)
                return;
        w->iow->tx_count++;
        w->iow->count += n;
}

/**
 * iowait_get_tid_work - return iowait_work for tid SE
 * @w: the iowait struct
 */
static inline struct iowait_work *iowait_get_tid_work(struct iowait *w)
{
        return &w->wait[IOWAIT_TID_SE];
}

/**
 * iowait_get_ib_work - return iowait_work for ib SE
 * @w: the iowait struct
 */
static inline struct iowait_work *iowait_get_ib_work(struct iowait *w)
{
        return &w->wait[IOWAIT_IB_SE];
}

/**
 * iowait_ioww_to_iow - return iowait given iowait_work
 * @w: the iowait_work struct
 */
static inline struct iowait *iowait_ioww_to_iow(struct iowait_work *w)
{
        if (likely(w))
                return w->iow;
        return NULL;
}

void iowait_cancel_work(struct iowait *w);
int iowait_set_work_flag(struct iowait_work *w);

#endif