// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2012-2022, Intel Corporation. All rights reserved.
 * Intel Management Engine Interface (Intel MEI) Linux driver
 */

#include <linux/export.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>

#include <linux/mei.h>

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

const char *mei_dev_state_str(int state)
{
#define MEI_DEV_STATE(state) case MEI_DEV_##state: return #state
        switch (state) {
        MEI_DEV_STATE(INITIALIZING);
        MEI_DEV_STATE(INIT_CLIENTS);
        MEI_DEV_STATE(ENABLED);
        MEI_DEV_STATE(RESETTING);
        MEI_DEV_STATE(DISABLED);
        MEI_DEV_STATE(POWERING_DOWN);
        MEI_DEV_STATE(POWER_DOWN);
        MEI_DEV_STATE(POWER_UP);
        default:
                return "unknown";
        }
#undef MEI_DEV_STATE
}

const char *mei_pg_state_str(enum mei_pg_state state)
{
#define MEI_PG_STATE(state) case MEI_PG_##state: return #state
        switch (state) {
        MEI_PG_STATE(OFF);
        MEI_PG_STATE(ON);
        default:
                return "unknown";
        }
#undef MEI_PG_STATE
}

/**
 * mei_fw_status2str - convert fw status registers to printable string
 *
 * @fw_status:  firmware status
 * @buf: string buffer at minimal size MEI_FW_STATUS_STR_SZ
 * @len: buffer len must be >= MEI_FW_STATUS_STR_SZ
 *
 * Return: number of bytes written or -EINVAL if buffer is to small
 */
ssize_t mei_fw_status2str(struct mei_fw_status *fw_status,
                          char *buf, size_t len)
{
        ssize_t cnt = 0;
        int i;

        buf[0] = '\0';

        if (len < MEI_FW_STATUS_STR_SZ)
                return -EINVAL;

        for (i = 0; i < fw_status->count; i++)
                cnt += scnprintf(buf + cnt, len - cnt, "%08X ",
                                fw_status->status[i]);

        /* drop last space */
        buf[cnt] = '\0';
        return cnt;
}
EXPORT_SYMBOL_GPL(mei_fw_status2str);

/**
 * mei_cancel_work - Cancel mei background jobs
 *
 * @dev: the device structure
 */
void mei_cancel_work(struct mei_device *dev)
{
        cancel_work_sync(&dev->reset_work);
        cancel_work_sync(&dev->bus_rescan_work);

        cancel_delayed_work_sync(&dev->timer_work);
}
EXPORT_SYMBOL_GPL(mei_cancel_work);

/**
 * mei_reset - resets host and fw.
 *
 * @dev: the device structure
 *
 * Return: 0 on success or < 0 if the reset hasn't succeeded
 */
int mei_reset(struct mei_device *dev)
{
        enum mei_dev_state state = dev->dev_state;
        bool interrupts_enabled;
        int ret;

        if (state != MEI_DEV_INITIALIZING &&
            state != MEI_DEV_DISABLED &&
            state != MEI_DEV_POWER_DOWN &&
            state != MEI_DEV_POWER_UP) {
                char fw_sts_str[MEI_FW_STATUS_STR_SZ];

                mei_fw_status_str(dev, fw_sts_str, MEI_FW_STATUS_STR_SZ);
                if (kind_is_gsc(dev) || kind_is_gscfi(dev)) {
                        dev_dbg(&dev->dev, "unexpected reset: dev_state = %s fw status = %s\n",
                                mei_dev_state_str(state), fw_sts_str);
                } else {
                        dev_warn(&dev->dev, "unexpected reset: dev_state = %s fw status = %s\n",
                                 mei_dev_state_str(state), fw_sts_str);
                }
        }

        mei_clear_interrupts(dev);

        /* we're already in reset, cancel the init timer
         * if the reset was called due the hbm protocol error
         * we need to call it before hw start
         * so the hbm watchdog won't kick in
         */
        mei_hbm_idle(dev);

        /* enter reset flow */
        interrupts_enabled = state != MEI_DEV_POWER_DOWN;
        mei_set_devstate(dev, MEI_DEV_RESETTING);

        dev->reset_count++;
        if (dev->reset_count > MEI_MAX_CONSEC_RESET) {
                dev_err(&dev->dev, "reset: reached maximal consecutive resets: disabling the device\n");
                mei_set_devstate(dev, MEI_DEV_DISABLED);
                return -ENODEV;
        }

        ret = mei_hw_reset(dev, interrupts_enabled);
        /* fall through and remove the sw state even if hw reset has failed */

        /* no need to clean up software state in case of power up */
        if (state != MEI_DEV_INITIALIZING && state != MEI_DEV_POWER_UP)
                mei_cl_all_disconnect(dev);

        mei_hbm_reset(dev);

        /* clean stale FW version */
        dev->fw_ver_received = 0;

        memset(dev->rd_msg_hdr, 0, sizeof(dev->rd_msg_hdr));

        if (ret) {
                dev_err(&dev->dev, "hw_reset failed ret = %d\n", ret);
                return ret;
        }

        if (state == MEI_DEV_POWER_DOWN) {
                dev_dbg(&dev->dev, "powering down: end of reset\n");
                mei_set_devstate(dev, MEI_DEV_DISABLED);
                return 0;
        }

        ret = mei_hw_start(dev);
        if (ret) {
                char fw_sts_str[MEI_FW_STATUS_STR_SZ];

                mei_fw_status_str(dev, fw_sts_str, MEI_FW_STATUS_STR_SZ);
                dev_err(&dev->dev, "hw_start failed ret = %d fw status = %s\n", ret, fw_sts_str);
                return ret;
        }

        if (dev->dev_state != MEI_DEV_RESETTING) {
                dev_dbg(&dev->dev, "wrong state = %d on link start\n", dev->dev_state);
                return 0;
        }

        dev_dbg(&dev->dev, "link is established start sending messages.\n");

        mei_set_devstate(dev, MEI_DEV_INIT_CLIENTS);
        ret = mei_hbm_start_req(dev);
        if (ret) {
                dev_err(&dev->dev, "hbm_start failed ret = %d\n", ret);
                mei_set_devstate(dev, MEI_DEV_RESETTING);
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(mei_reset);

/**
 * mei_start - initializes host and fw to start work.
 *
 * @dev: the device structure
 *
 * Return: 0 on success, <0 on failure.
 */
int mei_start(struct mei_device *dev)
{
        int ret;

        mutex_lock(&dev->device_lock);

        /* acknowledge interrupt and stop interrupts */
        mei_clear_interrupts(dev);

        ret = mei_hw_config(dev);
        if (ret)
                goto err;

        dev_dbg(&dev->dev, "reset in start the mei device.\n");

        dev->reset_count = 0;
        do {
                mei_set_devstate(dev, MEI_DEV_INITIALIZING);
                ret = mei_reset(dev);

                if (ret == -ENODEV || dev->dev_state == MEI_DEV_DISABLED) {
                        dev_err(&dev->dev, "reset failed ret = %d", ret);
                        goto err;
                }
        } while (ret);

        if (mei_hbm_start_wait(dev)) {
                dev_err(&dev->dev, "HBM haven't started");
                goto err;
        }

        if (!mei_hbm_version_is_supported(dev)) {
                dev_dbg(&dev->dev, "MEI start failed.\n");
                goto err;
        }

        dev_dbg(&dev->dev, "link layer has been established.\n");

        mutex_unlock(&dev->device_lock);
        return 0;
err:
        dev_err(&dev->dev, "link layer initialization failed.\n");
        mei_set_devstate(dev, MEI_DEV_DISABLED);
        mutex_unlock(&dev->device_lock);
        return -ENODEV;
}
EXPORT_SYMBOL_GPL(mei_start);

/**
 * mei_restart - restart device after suspend
 *
 * @dev: the device structure
 *
 * Return: 0 on success or -ENODEV if the restart hasn't succeeded
 */
int mei_restart(struct mei_device *dev)
{
        int err;

        mutex_lock(&dev->device_lock);

        mei_set_devstate(dev, MEI_DEV_POWER_UP);
        dev->reset_count = 0;

        err = mei_reset(dev);

        mutex_unlock(&dev->device_lock);

        if (err == -ENODEV || dev->dev_state == MEI_DEV_DISABLED) {
                dev_err(&dev->dev, "device disabled = %d\n", err);
                return -ENODEV;
        }

        /* try to start again */
        if (err)
                schedule_work(&dev->reset_work);


        return 0;
}
EXPORT_SYMBOL_GPL(mei_restart);

static void mei_reset_work(struct work_struct *work)
{
        struct mei_device *dev =
                container_of(work, struct mei_device,  reset_work);
        int ret;

        mei_clear_interrupts(dev);
        mei_synchronize_irq(dev);

        mutex_lock(&dev->device_lock);

        ret = mei_reset(dev);

        mutex_unlock(&dev->device_lock);

        if (dev->dev_state == MEI_DEV_DISABLED) {
                dev_err(&dev->dev, "device disabled = %d\n", ret);
                return;
        }

        /* retry reset in case of failure */
        if (ret)
                schedule_work(&dev->reset_work);
}

void mei_stop(struct mei_device *dev)
{
        dev_dbg(&dev->dev, "stopping the device.\n");

        mutex_lock(&dev->device_lock);
        mei_set_devstate(dev, MEI_DEV_POWERING_DOWN);
        mutex_unlock(&dev->device_lock);
        mei_cl_bus_remove_devices(dev);
        mutex_lock(&dev->device_lock);
        mei_set_devstate(dev, MEI_DEV_POWER_DOWN);
        mutex_unlock(&dev->device_lock);

        mei_cancel_work(dev);

        mei_clear_interrupts(dev);
        mei_synchronize_irq(dev);
        /* to catch HW-initiated reset */
        mei_cancel_work(dev);

        mutex_lock(&dev->device_lock);

        mei_reset(dev);
        /* move device to disabled state unconditionally */
        mei_set_devstate(dev, MEI_DEV_DISABLED);

        mutex_unlock(&dev->device_lock);
}
EXPORT_SYMBOL_GPL(mei_stop);

/**
 * mei_write_is_idle - check if the write queues are idle
 *
 * @dev: the device structure
 *
 * Return: true of there is no pending write
 */
bool mei_write_is_idle(struct mei_device *dev)
{
        bool idle = (dev->dev_state == MEI_DEV_ENABLED &&
                list_empty(&dev->ctrl_wr_list) &&
                list_empty(&dev->write_list)   &&
                list_empty(&dev->write_waiting_list));

        dev_dbg(&dev->dev, "write pg: is idle[%d] state=%s ctrl=%01d write=%01d wwait=%01d\n",
                idle,
                mei_dev_state_str(dev->dev_state),
                list_empty(&dev->ctrl_wr_list),
                list_empty(&dev->write_list),
                list_empty(&dev->write_waiting_list));

        return idle;
}
EXPORT_SYMBOL_GPL(mei_write_is_idle);

/**
 * mei_device_init - initialize mei_device structure
 *
 * @dev: the mei device
 * @parent: the parent device
 * @slow_fw: configure longer timeouts as FW is slow
 * @hw_ops: hw operations
 */
void mei_device_init(struct mei_device *dev,
                     struct device *parent,
                     bool slow_fw,
                     const struct mei_hw_ops *hw_ops)
{
        /* setup our list array */
        INIT_LIST_HEAD(&dev->file_list);
        INIT_LIST_HEAD(&dev->device_list);
        INIT_LIST_HEAD(&dev->me_clients);
        mutex_init(&dev->device_lock);
        init_rwsem(&dev->me_clients_rwsem);
        mutex_init(&dev->cl_bus_lock);
        init_waitqueue_head(&dev->wait_hw_ready);
        init_waitqueue_head(&dev->wait_pg);
        init_waitqueue_head(&dev->wait_hbm_start);
        dev->dev_state = MEI_DEV_UNINITIALIZED;
        init_waitqueue_head(&dev->wait_dev_state);
        dev->reset_count = 0;

        INIT_LIST_HEAD(&dev->write_list);
        INIT_LIST_HEAD(&dev->write_waiting_list);
        INIT_LIST_HEAD(&dev->ctrl_wr_list);
        INIT_LIST_HEAD(&dev->ctrl_rd_list);
        dev->tx_queue_limit = MEI_TX_QUEUE_LIMIT_DEFAULT;

        INIT_DELAYED_WORK(&dev->timer_work, mei_timer);
        INIT_WORK(&dev->reset_work, mei_reset_work);
        INIT_WORK(&dev->bus_rescan_work, mei_cl_bus_rescan_work);

        bitmap_zero(dev->host_clients_map, MEI_CLIENTS_MAX);
        dev->open_handle_count = 0;

        dev->pxp_mode = MEI_DEV_PXP_DEFAULT;
        dev->gsc_reset_to_pxp = MEI_DEV_RESET_TO_PXP_DEFAULT;

        /*
         * Reserving the first client ID
         * 0: Reserved for MEI Bus Message communications
         */
        bitmap_set(dev->host_clients_map, 0, 1);

        dev->pg_event = MEI_PG_EVENT_IDLE;
        dev->ops      = hw_ops;
        dev->parent   = parent;

        dev->timeouts.hw_ready = mei_secs_to_jiffies(MEI_HW_READY_TIMEOUT);
        dev->timeouts.connect = MEI_CONNECT_TIMEOUT;
        dev->timeouts.client_init = MEI_CLIENTS_INIT_TIMEOUT;
        dev->timeouts.pgi = mei_secs_to_jiffies(MEI_PGI_TIMEOUT);
        dev->timeouts.d0i3 = mei_secs_to_jiffies(MEI_D0I3_TIMEOUT);
        if (slow_fw) {
                dev->timeouts.cl_connect = mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT_SLOW);
                dev->timeouts.hbm = mei_secs_to_jiffies(MEI_HBM_TIMEOUT_SLOW);
                dev->timeouts.mkhi_recv = msecs_to_jiffies(MKHI_RCV_TIMEOUT_SLOW);
        } else {
                dev->timeouts.cl_connect = mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT);
                dev->timeouts.hbm = mei_secs_to_jiffies(MEI_HBM_TIMEOUT);
                dev->timeouts.mkhi_recv = msecs_to_jiffies(MKHI_RCV_TIMEOUT);
        }
        dev->timeouts.link_reset_wait = msecs_to_jiffies(MEI_LINK_RESET_WAIT_TIMEOUT_MSEC);
}
EXPORT_SYMBOL_GPL(mei_device_init);