// SPDX-License-Identifier: GPL-2.0+
/* Copyright (c) 2015-2016 Quantenna Communications. All rights reserved. */

#include <linux/types.h>
#include <linux/export.h>
#include <linux/slab.h>

#include "core.h"
#include "commands.h"
#include "event.h"
#include "bus.h"

#define QTNF_DEF_SYNC_CMD_TIMEOUT       (5 * HZ)

int qtnf_trans_send_cmd_with_resp(struct qtnf_bus *bus, struct sk_buff *cmd_skb,
                                  struct sk_buff **response_skb)
{
        struct qtnf_cmd_ctl_node *ctl_node = &bus->trans.curr_cmd;
        struct qlink_cmd *cmd = (void *)cmd_skb->data;
        int ret = 0;
        long status;
        bool resp_not_handled = true;
        struct sk_buff *resp_skb = NULL;

        if (unlikely(!response_skb)) {
                dev_kfree_skb(cmd_skb);
                return -EFAULT;
        }

        spin_lock(&ctl_node->resp_lock);
        ctl_node->seq_num++;
        cmd->seq_num = cpu_to_le16(ctl_node->seq_num);
        WARN(ctl_node->resp_skb, "qtnfmac: response skb not empty\n");
        ctl_node->waiting_for_resp = true;
        spin_unlock(&ctl_node->resp_lock);

        ret = qtnf_bus_control_tx(bus, cmd_skb);
        dev_kfree_skb(cmd_skb);

        if (unlikely(ret))
                goto out;

        status = wait_for_completion_interruptible_timeout(
                                                &ctl_node->cmd_resp_completion,
                                                QTNF_DEF_SYNC_CMD_TIMEOUT);

        spin_lock(&ctl_node->resp_lock);
        resp_not_handled = ctl_node->waiting_for_resp;
        resp_skb = ctl_node->resp_skb;
        ctl_node->resp_skb = NULL;
        ctl_node->waiting_for_resp = false;
        spin_unlock(&ctl_node->resp_lock);

        if (unlikely(status <= 0)) {
                if (status == 0) {
                        ret = -ETIMEDOUT;
                        pr_err("response timeout\n");
                } else {
                        ret = -EINTR;
                        pr_debug("interrupted\n");
                }
        }

        if (unlikely(!resp_skb || resp_not_handled)) {
                if (!ret)
                        ret = -EFAULT;

                goto out;
        }

        ret = 0;
        *response_skb = resp_skb;

out:
        if (unlikely(resp_skb && resp_not_handled))
                dev_kfree_skb(resp_skb);

        return ret;
}

static void qtnf_trans_signal_cmdresp(struct qtnf_bus *bus, struct sk_buff *skb)
{
        struct qtnf_cmd_ctl_node *ctl_node = &bus->trans.curr_cmd;
        const struct qlink_resp *resp = (const struct qlink_resp *)skb->data;
        const u16 recvd_seq_num = le16_to_cpu(resp->seq_num);

        spin_lock(&ctl_node->resp_lock);

        if (unlikely(!ctl_node->waiting_for_resp)) {
                pr_err("unexpected response\n");
                goto out_err;
        }

        if (unlikely(recvd_seq_num != ctl_node->seq_num)) {
                pr_err("seq num mismatch\n");
                goto out_err;
        }

        ctl_node->resp_skb = skb;
        ctl_node->waiting_for_resp = false;

        spin_unlock(&ctl_node->resp_lock);

        complete(&ctl_node->cmd_resp_completion);
        return;

out_err:
        spin_unlock(&ctl_node->resp_lock);
        dev_kfree_skb(skb);
}

static int qtnf_trans_event_enqueue(struct qtnf_bus *bus, struct sk_buff *skb)
{
        struct qtnf_qlink_transport *trans = &bus->trans;

        if (likely(skb_queue_len(&trans->event_queue) <
                   trans->event_queue_max_len)) {
                skb_queue_tail(&trans->event_queue, skb);
                queue_work(bus->workqueue, &bus->event_work);
        } else {
                pr_warn("event dropped due to queue overflow\n");
                dev_kfree_skb(skb);
                return -1;
        }

        return 0;
}

void qtnf_trans_init(struct qtnf_bus *bus)
{
        struct qtnf_qlink_transport *trans = &bus->trans;

        init_completion(&trans->curr_cmd.cmd_resp_completion);
        spin_lock_init(&trans->curr_cmd.resp_lock);

        spin_lock(&trans->curr_cmd.resp_lock);
        trans->curr_cmd.seq_num = 0;
        trans->curr_cmd.waiting_for_resp = false;
        trans->curr_cmd.resp_skb = NULL;
        spin_unlock(&trans->curr_cmd.resp_lock);

        /* Init event handling related fields */
        skb_queue_head_init(&trans->event_queue);
        trans->event_queue_max_len = QTNF_MAX_EVENT_QUEUE_LEN;
}

static void qtnf_trans_free_events(struct qtnf_bus *bus)
{
        struct sk_buff_head *event_queue = &bus->trans.event_queue;
        struct sk_buff *current_event_skb = skb_dequeue(event_queue);

        while (current_event_skb) {
                dev_kfree_skb_any(current_event_skb);
                current_event_skb = skb_dequeue(event_queue);
        }
}

void qtnf_trans_free(struct qtnf_bus *bus)
{
        if (!bus) {
                pr_err("invalid bus pointer\n");
                return;
        }

        qtnf_trans_free_events(bus);
}

int qtnf_trans_handle_rx_ctl_packet(struct qtnf_bus *bus, struct sk_buff *skb)
{
        const struct qlink_msg_header *header = (void *)skb->data;
        int ret = -1;

        if (unlikely(skb->len < sizeof(*header))) {
                pr_warn("packet is too small: %u\n", skb->len);
                dev_kfree_skb(skb);
                return -EINVAL;
        }

        if (unlikely(skb->len != le16_to_cpu(header->len))) {
                pr_warn("cmd reply length mismatch: %u != %u\n",
                        skb->len, le16_to_cpu(header->len));
                dev_kfree_skb(skb);
                return -EFAULT;
        }

        switch (le16_to_cpu(header->type)) {
        case QLINK_MSG_TYPE_CMDRSP:
                if (unlikely(skb->len < sizeof(struct qlink_cmd))) {
                        pr_warn("cmd reply too short: %u\n", skb->len);
                        dev_kfree_skb(skb);
                        break;
                }

                qtnf_trans_signal_cmdresp(bus, skb);
                break;
        case QLINK_MSG_TYPE_EVENT:
                if (unlikely(skb->len < sizeof(struct qlink_event))) {
                        pr_warn("event too short: %u\n", skb->len);
                        dev_kfree_skb(skb);
                        break;
                }

                ret = qtnf_trans_event_enqueue(bus, skb);
                break;
        default:
                pr_warn("unknown packet type: %x\n", le16_to_cpu(header->type));
                dev_kfree_skb(skb);
                break;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(qtnf_trans_handle_rx_ctl_packet);