/*
 *
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * Copyright (c) 2003-2012, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */


#include <linux/export.h>
#include <linux/kthread.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/jiffies.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>

#include <linux/mei.h>

#include "mei_dev.h"
#include "hbm.h"
#include "client.h"


/**
 * mei_irq_compl_handler - dispatch complete handlers
 *      for the completed callbacks
 *
 * @dev: mei device
 * @cmpl_list: list of completed cbs
 */
void mei_irq_compl_handler(struct mei_device *dev, struct list_head *cmpl_list)
{
        struct mei_cl_cb *cb, *next;
        struct mei_cl *cl;

        list_for_each_entry_safe(cb, next, cmpl_list, list) {
                cl = cb->cl;
                list_del_init(&cb->list);

                dev_dbg(dev->dev, "completing call back.\n");
                mei_cl_complete(cl, cb);
        }
}
EXPORT_SYMBOL_GPL(mei_irq_compl_handler);

/**
 * mei_cl_hbm_equal - check if hbm is addressed to the client
 *
 * @cl: host client
 * @mei_hdr: header of mei client message
 *
 * Return: true if matches, false otherwise
 */
static inline int mei_cl_hbm_equal(struct mei_cl *cl,
                        struct mei_msg_hdr *mei_hdr)
{
        return  mei_cl_host_addr(cl) == mei_hdr->host_addr &&
                mei_cl_me_id(cl) == mei_hdr->me_addr;
}

/**
 * mei_irq_discard_msg  - discard received message
 *
 * @dev: mei device
 * @hdr: message header
 */
static void mei_irq_discard_msg(struct mei_device *dev, struct mei_msg_hdr *hdr)
{
        /*
         * no need to check for size as it is guarantied
         * that length fits into rd_msg_buf
         */
        mei_read_slots(dev, dev->rd_msg_buf, hdr->length);
        dev_dbg(dev->dev, "discarding message " MEI_HDR_FMT "\n",
                MEI_HDR_PRM(hdr));
}

/**
 * mei_cl_irq_read_msg - process client message
 *
 * @cl: reading client
 * @mei_hdr: header of mei client message
 * @cmpl_list: completion list
 *
 * Return: always 0
 */
static int mei_cl_irq_read_msg(struct mei_cl *cl,
                               struct mei_msg_hdr *mei_hdr,
                               struct list_head *cmpl_list)
{
        struct mei_device *dev = cl->dev;
        struct mei_cl_cb *cb;
        size_t buf_sz;

        cb = list_first_entry_or_null(&cl->rd_pending, struct mei_cl_cb, list);
        if (!cb) {
                if (!mei_cl_is_fixed_address(cl)) {
                        cl_err(dev, cl, "pending read cb not found\n");
                        goto discard;
                }
                cb = mei_cl_alloc_cb(cl, mei_cl_mtu(cl), MEI_FOP_READ, cl->fp);
                if (!cb)
                        goto discard;
                list_add_tail(&cb->list, &cl->rd_pending);
        }

        if (!mei_cl_is_connected(cl)) {
                cl_dbg(dev, cl, "not connected\n");
                cb->status = -ENODEV;
                goto discard;
        }

        buf_sz = mei_hdr->length + cb->buf_idx;
        /* catch for integer overflow */
        if (buf_sz < cb->buf_idx) {
                cl_err(dev, cl, "message is too big len %d idx %zu\n",
                       mei_hdr->length, cb->buf_idx);
                cb->status = -EMSGSIZE;
                goto discard;
        }

        if (cb->buf.size < buf_sz) {
                cl_dbg(dev, cl, "message overflow. size %zu len %d idx %zu\n",
                        cb->buf.size, mei_hdr->length, cb->buf_idx);
                cb->status = -EMSGSIZE;
                goto discard;
        }

        mei_read_slots(dev, cb->buf.data + cb->buf_idx, mei_hdr->length);

        cb->buf_idx += mei_hdr->length;

        if (mei_hdr->msg_complete) {
                cl_dbg(dev, cl, "completed read length = %zu\n", cb->buf_idx);
                list_move_tail(&cb->list, cmpl_list);
        } else {
                pm_runtime_mark_last_busy(dev->dev);
                pm_request_autosuspend(dev->dev);
        }

        return 0;

discard:
        if (cb)
                list_move_tail(&cb->list, cmpl_list);
        mei_irq_discard_msg(dev, mei_hdr);
        return 0;
}

/**
 * mei_cl_irq_disconnect_rsp - send disconnection response message
 *
 * @cl: client
 * @cb: callback block.
 * @cmpl_list: complete list.
 *
 * Return: 0, OK; otherwise, error.
 */
static int mei_cl_irq_disconnect_rsp(struct mei_cl *cl, struct mei_cl_cb *cb,
                                     struct list_head *cmpl_list)
{
        struct mei_device *dev = cl->dev;
        u32 msg_slots;
        int slots;
        int ret;

        slots = mei_hbuf_empty_slots(dev);
        msg_slots = mei_data2slots(sizeof(struct hbm_client_connect_response));

        if (slots < msg_slots)
                return -EMSGSIZE;

        ret = mei_hbm_cl_disconnect_rsp(dev, cl);
        list_move_tail(&cb->list, cmpl_list);

        return ret;
}

/**
 * mei_cl_irq_read - processes client read related operation from the
 *      interrupt thread context - request for flow control credits
 *
 * @cl: client
 * @cb: callback block.
 * @cmpl_list: complete list.
 *
 * Return: 0, OK; otherwise, error.
 */
static int mei_cl_irq_read(struct mei_cl *cl, struct mei_cl_cb *cb,
                           struct list_head *cmpl_list)
{
        struct mei_device *dev = cl->dev;
        u32 msg_slots;
        int slots;
        int ret;

        if (!list_empty(&cl->rd_pending))
                return 0;

        msg_slots = mei_data2slots(sizeof(struct hbm_flow_control));
        slots = mei_hbuf_empty_slots(dev);

        if (slots < msg_slots)
                return -EMSGSIZE;

        ret = mei_hbm_cl_flow_control_req(dev, cl);
        if (ret) {
                cl->status = ret;
                cb->buf_idx = 0;
                list_move_tail(&cb->list, cmpl_list);
                return ret;
        }

        list_move_tail(&cb->list, &cl->rd_pending);

        return 0;
}

static inline bool hdr_is_hbm(struct mei_msg_hdr *mei_hdr)
{
        return mei_hdr->host_addr == 0 && mei_hdr->me_addr == 0;
}

static inline bool hdr_is_fixed(struct mei_msg_hdr *mei_hdr)
{
        return mei_hdr->host_addr == 0 && mei_hdr->me_addr != 0;
}

static inline int hdr_is_valid(u32 msg_hdr)
{
        struct mei_msg_hdr *mei_hdr;

        mei_hdr = (struct mei_msg_hdr *)&msg_hdr;
        if (!msg_hdr || mei_hdr->reserved)
                return -EBADMSG;

        return 0;
}

/**
 * mei_irq_read_handler - bottom half read routine after ISR to
 * handle the read processing.
 *
 * @dev: the device structure
 * @cmpl_list: An instance of our list structure
 * @slots: slots to read.
 *
 * Return: 0 on success, <0 on failure.
 */
int mei_irq_read_handler(struct mei_device *dev,
                         struct list_head *cmpl_list, s32 *slots)
{
        struct mei_msg_hdr *mei_hdr;
        struct mei_cl *cl;
        int ret;

        if (!dev->rd_msg_hdr) {
                dev->rd_msg_hdr = mei_read_hdr(dev);
                (*slots)--;
                dev_dbg(dev->dev, "slots =%08x.\n", *slots);

                ret = hdr_is_valid(dev->rd_msg_hdr);
                if (ret) {
                        dev_err(dev->dev, "corrupted message header 0x%08X\n",
                                dev->rd_msg_hdr);
                        goto end;
                }
        }

        mei_hdr = (struct mei_msg_hdr *)&dev->rd_msg_hdr;
        dev_dbg(dev->dev, MEI_HDR_FMT, MEI_HDR_PRM(mei_hdr));

        if (mei_slots2data(*slots) < mei_hdr->length) {
                dev_err(dev->dev, "less data available than length=%08x.\n",
                                *slots);
                /* we can't read the message */
                ret = -ENODATA;
                goto end;
        }

        /*  HBM message */
        if (hdr_is_hbm(mei_hdr)) {
                ret = mei_hbm_dispatch(dev, mei_hdr);
                if (ret) {
                        dev_dbg(dev->dev, "mei_hbm_dispatch failed ret = %d\n",
                                        ret);
                        goto end;
                }
                goto reset_slots;
        }

        /* find recipient cl */
        list_for_each_entry(cl, &dev->file_list, link) {
                if (mei_cl_hbm_equal(cl, mei_hdr)) {
                        cl_dbg(dev, cl, "got a message\n");
                        break;
                }
        }

        /* if no recipient cl was found we assume corrupted header */
        if (&cl->link == &dev->file_list) {
                /* A message for not connected fixed address clients
                 * should be silently discarded
                 */
                if (hdr_is_fixed(mei_hdr)) {
                        mei_irq_discard_msg(dev, mei_hdr);
                        ret = 0;
                        goto reset_slots;
                }
                dev_err(dev->dev, "no destination client found 0x%08X\n",
                                dev->rd_msg_hdr);
                ret = -EBADMSG;
                goto end;
        }

        ret = mei_cl_irq_read_msg(cl, mei_hdr, cmpl_list);


reset_slots:
        /* reset the number of slots and header */
        *slots = mei_count_full_read_slots(dev);
        dev->rd_msg_hdr = 0;

        if (*slots == -EOVERFLOW) {
                /* overflow - reset */
                dev_err(dev->dev, "resetting due to slots overflow.\n");
                /* set the event since message has been read */
                ret = -ERANGE;
                goto end;
        }
end:
        return ret;
}
EXPORT_SYMBOL_GPL(mei_irq_read_handler);


/**
 * mei_irq_write_handler -  dispatch write requests
 *  after irq received
 *
 * @dev: the device structure
 * @cmpl_list: An instance of our list structure
 *
 * Return: 0 on success, <0 on failure.
 */
int mei_irq_write_handler(struct mei_device *dev, struct list_head *cmpl_list)
{

        struct mei_cl *cl;
        struct mei_cl_cb *cb, *next;
        s32 slots;
        int ret;


        if (!mei_hbuf_acquire(dev))
                return 0;

        slots = mei_hbuf_empty_slots(dev);
        if (slots <= 0)
                return -EMSGSIZE;

        /* complete all waiting for write CB */
        dev_dbg(dev->dev, "complete all waiting for write cb.\n");

        list_for_each_entry_safe(cb, next, &dev->write_waiting_list, list) {
                cl = cb->cl;

                cl->status = 0;
                cl_dbg(dev, cl, "MEI WRITE COMPLETE\n");
                cl->writing_state = MEI_WRITE_COMPLETE;
                list_move_tail(&cb->list, cmpl_list);
        }

        /* complete control write list CB */
        dev_dbg(dev->dev, "complete control write list cb.\n");
        list_for_each_entry_safe(cb, next, &dev->ctrl_wr_list, list) {
                cl = cb->cl;
                switch (cb->fop_type) {
                case MEI_FOP_DISCONNECT:
                        /* send disconnect message */
                        ret = mei_cl_irq_disconnect(cl, cb, cmpl_list);
                        if (ret)
                                return ret;

                        break;
                case MEI_FOP_READ:
                        /* send flow control message */
                        ret = mei_cl_irq_read(cl, cb, cmpl_list);
                        if (ret)
                                return ret;

                        break;
                case MEI_FOP_CONNECT:
                        /* connect message */
                        ret = mei_cl_irq_connect(cl, cb, cmpl_list);
                        if (ret)
                                return ret;

                        break;
                case MEI_FOP_DISCONNECT_RSP:
                        /* send disconnect resp */
                        ret = mei_cl_irq_disconnect_rsp(cl, cb, cmpl_list);
                        if (ret)
                                return ret;
                        break;

                case MEI_FOP_NOTIFY_START:
                case MEI_FOP_NOTIFY_STOP:
                        ret = mei_cl_irq_notify(cl, cb, cmpl_list);
                        if (ret)
                                return ret;
                        break;
                default:
                        BUG();
                }

        }
        /* complete  write list CB */
        dev_dbg(dev->dev, "complete write list cb.\n");
        list_for_each_entry_safe(cb, next, &dev->write_list, list) {
                cl = cb->cl;
                ret = mei_cl_irq_write(cl, cb, cmpl_list);
                if (ret)
                        return ret;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(mei_irq_write_handler);


/**
 * mei_connect_timeout  - connect/disconnect timeouts
 *
 * @cl: host client
 */
static void mei_connect_timeout(struct mei_cl *cl)
{
        struct mei_device *dev = cl->dev;

        if (cl->state == MEI_FILE_CONNECTING) {
                if (dev->hbm_f_dot_supported) {
                        cl->state = MEI_FILE_DISCONNECT_REQUIRED;
                        wake_up(&cl->wait);
                        return;
                }
        }
        mei_reset(dev);
}

#define MEI_STALL_TIMER_FREQ (2 * HZ)
/**
 * mei_schedule_stall_timer - re-arm stall_timer work
 *
 * Schedule stall timer
 *
 * @dev: the device structure
 */
void mei_schedule_stall_timer(struct mei_device *dev)
{
        schedule_delayed_work(&dev->timer_work, MEI_STALL_TIMER_FREQ);
}

/**
 * mei_timer - timer function.
 *
 * @work: pointer to the work_struct structure
 *
 */
void mei_timer(struct work_struct *work)
{
        struct mei_cl *cl;
        struct mei_device *dev = container_of(work,
                                        struct mei_device, timer_work.work);
        bool reschedule_timer = false;

        mutex_lock(&dev->device_lock);

        /* Catch interrupt stalls during HBM init handshake */
        if (dev->dev_state == MEI_DEV_INIT_CLIENTS &&
            dev->hbm_state != MEI_HBM_IDLE) {

                if (dev->init_clients_timer) {
                        if (--dev->init_clients_timer == 0) {
                                dev_err(dev->dev, "timer: init clients timeout hbm_state = %d.\n",
                                        dev->hbm_state);
                                mei_reset(dev);
                                goto out;
                        }
                        reschedule_timer = true;
                }
        }

        if (dev->dev_state != MEI_DEV_ENABLED)
                goto out;

        /*** connect/disconnect timeouts ***/
        list_for_each_entry(cl, &dev->file_list, link) {
                if (cl->timer_count) {
                        if (--cl->timer_count == 0) {
                                dev_err(dev->dev, "timer: connect/disconnect timeout.\n");
                                mei_connect_timeout(cl);
                                goto out;
                        }
                        reschedule_timer = true;
                }
        }

out:
        if (dev->dev_state != MEI_DEV_DISABLED && reschedule_timer)
                mei_schedule_stall_timer(dev);

        mutex_unlock(&dev->device_lock);
}