// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
 *
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/mhi.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include "internal.h"

/*
 * Not all MHI state transitions are synchronous. Transitions like Linkdown,
 * SYS_ERR, and shutdown can happen anytime asynchronously. This function will
 * transition to a new state only if we're allowed to.
 *
 * Priority increases as we go down. For instance, from any state in L0, the
 * transition can be made to states in L1, L2 and L3. A notable exception to
 * this rule is state DISABLE.  From DISABLE state we can only transition to
 * POR state. Also, while in L2 state, user cannot jump back to previous
 * L1 or L0 states.
 *
 * Valid transitions:
 * L0: DISABLE <--> POR
 *     POR <--> POR
 *     POR -> M0 -> M2 --> M0
 *     POR -> FW_DL_ERR
 *     FW_DL_ERR <--> FW_DL_ERR
 *     M0 <--> M0
 *     M0 -> FW_DL_ERR
 *     M0 -> M3_ENTER -> M3 -> M3_EXIT --> M0
 * L1: SYS_ERR_DETECT -> SYS_ERR_PROCESS --> POR
 * L2: SHUTDOWN_PROCESS -> DISABLE
 * L3: LD_ERR_FATAL_DETECT <--> LD_ERR_FATAL_DETECT
 *     LD_ERR_FATAL_DETECT -> SHUTDOWN_PROCESS
 */
static struct mhi_pm_transitions const dev_state_transitions[] = {
        /* L0 States */
        {
                MHI_PM_DISABLE,
                MHI_PM_POR
        },
        {
                MHI_PM_POR,
                MHI_PM_POR | MHI_PM_DISABLE | MHI_PM_M0 |
                MHI_PM_SYS_ERR_DETECT | MHI_PM_SHUTDOWN_PROCESS |
                MHI_PM_LD_ERR_FATAL_DETECT | MHI_PM_FW_DL_ERR
        },
        {
                MHI_PM_M0,
                MHI_PM_M0 | MHI_PM_M2 | MHI_PM_M3_ENTER |
                MHI_PM_SYS_ERR_DETECT | MHI_PM_SHUTDOWN_PROCESS |
                MHI_PM_LD_ERR_FATAL_DETECT | MHI_PM_FW_DL_ERR
        },
        {
                MHI_PM_M2,
                MHI_PM_M0 | MHI_PM_SYS_ERR_DETECT | MHI_PM_SHUTDOWN_PROCESS |
                MHI_PM_LD_ERR_FATAL_DETECT
        },
        {
                MHI_PM_M3_ENTER,
                MHI_PM_M3 | MHI_PM_SYS_ERR_DETECT | MHI_PM_SHUTDOWN_PROCESS |
                MHI_PM_LD_ERR_FATAL_DETECT
        },
        {
                MHI_PM_M3,
                MHI_PM_M3_EXIT | MHI_PM_SYS_ERR_DETECT |
                MHI_PM_SHUTDOWN_PROCESS | MHI_PM_LD_ERR_FATAL_DETECT
        },
        {
                MHI_PM_M3_EXIT,
                MHI_PM_M0 | MHI_PM_SYS_ERR_DETECT | MHI_PM_SHUTDOWN_PROCESS |
                MHI_PM_LD_ERR_FATAL_DETECT
        },
        {
                MHI_PM_FW_DL_ERR,
                MHI_PM_FW_DL_ERR | MHI_PM_SYS_ERR_DETECT |
                MHI_PM_SHUTDOWN_PROCESS | MHI_PM_LD_ERR_FATAL_DETECT
        },
        /* L1 States */
        {
                MHI_PM_SYS_ERR_DETECT,
                MHI_PM_SYS_ERR_PROCESS | MHI_PM_SHUTDOWN_PROCESS |
                MHI_PM_LD_ERR_FATAL_DETECT
        },
        {
                MHI_PM_SYS_ERR_PROCESS,
                MHI_PM_POR | MHI_PM_SHUTDOWN_PROCESS |
                MHI_PM_LD_ERR_FATAL_DETECT
        },
        /* L2 States */
        {
                MHI_PM_SHUTDOWN_PROCESS,
                MHI_PM_DISABLE | MHI_PM_LD_ERR_FATAL_DETECT
        },
        /* L3 States */
        {
                MHI_PM_LD_ERR_FATAL_DETECT,
                MHI_PM_LD_ERR_FATAL_DETECT | MHI_PM_SHUTDOWN_PROCESS
        },
};

enum mhi_pm_state __must_check mhi_tryset_pm_state(struct mhi_controller *mhi_cntrl,
                                                   enum mhi_pm_state state)
{
        unsigned long cur_state = mhi_cntrl->pm_state;
        int index = find_last_bit(&cur_state, 32);

        if (unlikely(index >= ARRAY_SIZE(dev_state_transitions)))
                return cur_state;

        if (unlikely(dev_state_transitions[index].from_state != cur_state))
                return cur_state;

        if (unlikely(!(dev_state_transitions[index].to_states & state)))
                return cur_state;

        mhi_cntrl->pm_state = state;
        return mhi_cntrl->pm_state;
}

void mhi_set_mhi_state(struct mhi_controller *mhi_cntrl, enum mhi_state state)
{
        if (state == MHI_STATE_RESET) {
                mhi_write_reg_field(mhi_cntrl, mhi_cntrl->regs, MHICTRL,
                                    MHICTRL_RESET_MASK, MHICTRL_RESET_SHIFT, 1);
        } else {
                mhi_write_reg_field(mhi_cntrl, mhi_cntrl->regs, MHICTRL,
                                    MHICTRL_MHISTATE_MASK,
                                    MHICTRL_MHISTATE_SHIFT, state);
        }
}

/* NOP for backward compatibility, host allowed to ring DB in M2 state */
static void mhi_toggle_dev_wake_nop(struct mhi_controller *mhi_cntrl)
{
}

static void mhi_toggle_dev_wake(struct mhi_controller *mhi_cntrl)
{
        mhi_cntrl->wake_get(mhi_cntrl, false);
        mhi_cntrl->wake_put(mhi_cntrl, true);
}

/* Handle device ready state transition */
int mhi_ready_state_transition(struct mhi_controller *mhi_cntrl)
{
        void __iomem *base = mhi_cntrl->regs;
        struct mhi_event *mhi_event;
        enum mhi_pm_state cur_state;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        u32 reset = 1, ready = 0;
        int ret, i;

        /* Wait for RESET to be cleared and READY bit to be set by the device */
        wait_event_timeout(mhi_cntrl->state_event,
                           MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
                           mhi_read_reg_field(mhi_cntrl, base, MHICTRL,
                                              MHICTRL_RESET_MASK,
                                              MHICTRL_RESET_SHIFT, &reset) ||
                           mhi_read_reg_field(mhi_cntrl, base, MHISTATUS,
                                              MHISTATUS_READY_MASK,
                                              MHISTATUS_READY_SHIFT, &ready) ||
                           (!reset && ready),
                           msecs_to_jiffies(mhi_cntrl->timeout_ms));

        /* Check if device entered error state */
        if (MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
                dev_err(dev, "Device link is not accessible\n");
                return -EIO;
        }

        /* Timeout if device did not transition to ready state */
        if (reset || !ready) {
                dev_err(dev, "Device Ready timeout\n");
                return -ETIMEDOUT;
        }

        dev_dbg(dev, "Device in READY State\n");
        write_lock_irq(&mhi_cntrl->pm_lock);
        cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_POR);
        mhi_cntrl->dev_state = MHI_STATE_READY;
        write_unlock_irq(&mhi_cntrl->pm_lock);

        if (cur_state != MHI_PM_POR) {
                dev_err(dev, "Error moving to state %s from %s\n",
                        to_mhi_pm_state_str(MHI_PM_POR),
                        to_mhi_pm_state_str(cur_state));
                return -EIO;
        }

        read_lock_bh(&mhi_cntrl->pm_lock);
        if (!MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
                dev_err(dev, "Device registers not accessible\n");
                goto error_mmio;
        }

        /* Configure MMIO registers */
        ret = mhi_init_mmio(mhi_cntrl);
        if (ret) {
                dev_err(dev, "Error configuring MMIO registers\n");
                goto error_mmio;
        }

        /* Add elements to all SW event rings */
        mhi_event = mhi_cntrl->mhi_event;
        for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
                struct mhi_ring *ring = &mhi_event->ring;

                /* Skip if this is an offload or HW event */
                if (mhi_event->offload_ev || mhi_event->hw_ring)
                        continue;

                ring->wp = ring->base + ring->len - ring->el_size;
                *ring->ctxt_wp = ring->iommu_base + ring->len - ring->el_size;
                /* Update all cores */
                smp_wmb();

                /* Ring the event ring db */
                spin_lock_irq(&mhi_event->lock);
                mhi_ring_er_db(mhi_event);
                spin_unlock_irq(&mhi_event->lock);
        }

        /* Set MHI to M0 state */
        mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
        read_unlock_bh(&mhi_cntrl->pm_lock);

        return 0;

error_mmio:
        read_unlock_bh(&mhi_cntrl->pm_lock);

        return -EIO;
}

int mhi_pm_m0_transition(struct mhi_controller *mhi_cntrl)
{
        enum mhi_pm_state cur_state;
        struct mhi_chan *mhi_chan;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        int i;

        write_lock_irq(&mhi_cntrl->pm_lock);
        mhi_cntrl->dev_state = MHI_STATE_M0;
        cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M0);
        write_unlock_irq(&mhi_cntrl->pm_lock);
        if (unlikely(cur_state != MHI_PM_M0)) {
                dev_err(dev, "Unable to transition to M0 state\n");
                return -EIO;
        }

        /* Wake up the device */
        read_lock_bh(&mhi_cntrl->pm_lock);
        mhi_cntrl->wake_get(mhi_cntrl, true);

        /* Ring all event rings and CMD ring only if we're in mission mode */
        if (MHI_IN_MISSION_MODE(mhi_cntrl->ee)) {
                struct mhi_event *mhi_event = mhi_cntrl->mhi_event;
                struct mhi_cmd *mhi_cmd =
                        &mhi_cntrl->mhi_cmd[PRIMARY_CMD_RING];

                for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
                        if (mhi_event->offload_ev)
                                continue;

                        spin_lock_irq(&mhi_event->lock);
                        mhi_ring_er_db(mhi_event);
                        spin_unlock_irq(&mhi_event->lock);
                }

                /* Only ring primary cmd ring if ring is not empty */
                spin_lock_irq(&mhi_cmd->lock);
                if (mhi_cmd->ring.rp != mhi_cmd->ring.wp)
                        mhi_ring_cmd_db(mhi_cntrl, mhi_cmd);
                spin_unlock_irq(&mhi_cmd->lock);
        }

        /* Ring channel DB registers */
        mhi_chan = mhi_cntrl->mhi_chan;
        for (i = 0; i < mhi_cntrl->max_chan; i++, mhi_chan++) {
                struct mhi_ring *tre_ring = &mhi_chan->tre_ring;

                if (mhi_chan->db_cfg.reset_req) {
                        write_lock_irq(&mhi_chan->lock);
                        mhi_chan->db_cfg.db_mode = true;
                        write_unlock_irq(&mhi_chan->lock);
                }

                read_lock_irq(&mhi_chan->lock);

                /* Only ring DB if ring is not empty */
                if (tre_ring->base && tre_ring->wp  != tre_ring->rp)
                        mhi_ring_chan_db(mhi_cntrl, mhi_chan);
                read_unlock_irq(&mhi_chan->lock);
        }

        mhi_cntrl->wake_put(mhi_cntrl, false);
        read_unlock_bh(&mhi_cntrl->pm_lock);
        wake_up_all(&mhi_cntrl->state_event);

        return 0;
}

/*
 * After receiving the MHI state change event from the device indicating the
 * transition to M1 state, the host can transition the device to M2 state
 * for keeping it in low power state.
 */
void mhi_pm_m1_transition(struct mhi_controller *mhi_cntrl)
{
        enum mhi_pm_state state;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;

        write_lock_irq(&mhi_cntrl->pm_lock);
        state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M2);
        if (state == MHI_PM_M2) {
                mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M2);
                mhi_cntrl->dev_state = MHI_STATE_M2;

                write_unlock_irq(&mhi_cntrl->pm_lock);
                wake_up_all(&mhi_cntrl->state_event);

                /* If there are any pending resources, exit M2 immediately */
                if (unlikely(atomic_read(&mhi_cntrl->pending_pkts) ||
                             atomic_read(&mhi_cntrl->dev_wake))) {
                        dev_dbg(dev,
                                "Exiting M2, pending_pkts: %d dev_wake: %d\n",
                                atomic_read(&mhi_cntrl->pending_pkts),
                                atomic_read(&mhi_cntrl->dev_wake));
                        read_lock_bh(&mhi_cntrl->pm_lock);
                        mhi_cntrl->wake_get(mhi_cntrl, true);
                        mhi_cntrl->wake_put(mhi_cntrl, true);
                        read_unlock_bh(&mhi_cntrl->pm_lock);
                } else {
                        mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_IDLE);
                }
        } else {
                write_unlock_irq(&mhi_cntrl->pm_lock);
        }
}

/* MHI M3 completion handler */
int mhi_pm_m3_transition(struct mhi_controller *mhi_cntrl)
{
        enum mhi_pm_state state;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;

        write_lock_irq(&mhi_cntrl->pm_lock);
        mhi_cntrl->dev_state = MHI_STATE_M3;
        state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M3);
        write_unlock_irq(&mhi_cntrl->pm_lock);
        if (state != MHI_PM_M3) {
                dev_err(dev, "Unable to transition to M3 state\n");
                return -EIO;
        }

        wake_up_all(&mhi_cntrl->state_event);

        return 0;
}

/* Handle device Mission Mode transition */
static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
{
        struct mhi_event *mhi_event;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        int i, ret;

        dev_dbg(dev, "Processing Mission Mode transition\n");

        write_lock_irq(&mhi_cntrl->pm_lock);
        if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state))
                mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
        write_unlock_irq(&mhi_cntrl->pm_lock);

        if (!MHI_IN_MISSION_MODE(mhi_cntrl->ee))
                return -EIO;

        wake_up_all(&mhi_cntrl->state_event);

        mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_MISSION_MODE);

        /* Force MHI to be in M0 state before continuing */
        ret = __mhi_device_get_sync(mhi_cntrl);
        if (ret)
                return ret;

        read_lock_bh(&mhi_cntrl->pm_lock);

        if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
                ret = -EIO;
                goto error_mission_mode;
        }

        /* Add elements to all HW event rings */
        mhi_event = mhi_cntrl->mhi_event;
        for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
                struct mhi_ring *ring = &mhi_event->ring;

                if (mhi_event->offload_ev || !mhi_event->hw_ring)
                        continue;

                ring->wp = ring->base + ring->len - ring->el_size;
                *ring->ctxt_wp = ring->iommu_base + ring->len - ring->el_size;
                /* Update to all cores */
                smp_wmb();

                spin_lock_irq(&mhi_event->lock);
                if (MHI_DB_ACCESS_VALID(mhi_cntrl))
                        mhi_ring_er_db(mhi_event);
                spin_unlock_irq(&mhi_event->lock);
        }

        read_unlock_bh(&mhi_cntrl->pm_lock);

        /*
         * The MHI devices are only created when the client device switches its
         * Execution Environment (EE) to either SBL or AMSS states
         */
        mhi_create_devices(mhi_cntrl);

        read_lock_bh(&mhi_cntrl->pm_lock);

error_mission_mode:
        mhi_cntrl->wake_put(mhi_cntrl, false);
        read_unlock_bh(&mhi_cntrl->pm_lock);

        return ret;
}

/* Handle SYS_ERR and Shutdown transitions */
static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl,
                                      enum mhi_pm_state transition_state)
{
        enum mhi_pm_state cur_state, prev_state;
        struct mhi_event *mhi_event;
        struct mhi_cmd_ctxt *cmd_ctxt;
        struct mhi_cmd *mhi_cmd;
        struct mhi_event_ctxt *er_ctxt;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        int ret, i;

        dev_dbg(dev, "Transitioning from PM state: %s to: %s\n",
                to_mhi_pm_state_str(mhi_cntrl->pm_state),
                to_mhi_pm_state_str(transition_state));

        /* We must notify MHI control driver so it can clean up first */
        if (transition_state == MHI_PM_SYS_ERR_PROCESS)
                mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_SYS_ERROR);

        mutex_lock(&mhi_cntrl->pm_mutex);
        write_lock_irq(&mhi_cntrl->pm_lock);
        prev_state = mhi_cntrl->pm_state;
        cur_state = mhi_tryset_pm_state(mhi_cntrl, transition_state);
        if (cur_state == transition_state) {
                mhi_cntrl->ee = MHI_EE_DISABLE_TRANSITION;
                mhi_cntrl->dev_state = MHI_STATE_RESET;
        }
        write_unlock_irq(&mhi_cntrl->pm_lock);

        /* Wake up threads waiting for state transition */
        wake_up_all(&mhi_cntrl->state_event);

        if (cur_state != transition_state) {
                dev_err(dev, "Failed to transition to state: %s from: %s\n",
                        to_mhi_pm_state_str(transition_state),
                        to_mhi_pm_state_str(cur_state));
                mutex_unlock(&mhi_cntrl->pm_mutex);
                return;
        }

        /* Trigger MHI RESET so that the device will not access host memory */
        if (MHI_REG_ACCESS_VALID(prev_state)) {
                u32 in_reset = -1;
                unsigned long timeout = msecs_to_jiffies(mhi_cntrl->timeout_ms);

                dev_dbg(dev, "Triggering MHI Reset in device\n");
                mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);

                /* Wait for the reset bit to be cleared by the device */
                ret = wait_event_timeout(mhi_cntrl->state_event,
                                         mhi_read_reg_field(mhi_cntrl,
                                                            mhi_cntrl->regs,
                                                            MHICTRL,
                                                            MHICTRL_RESET_MASK,
                                                            MHICTRL_RESET_SHIFT,
                                                            &in_reset) ||
                                        !in_reset, timeout);
                if ((!ret || in_reset) && cur_state == MHI_PM_SYS_ERR_PROCESS) {
                        dev_err(dev, "Device failed to exit MHI Reset state\n");
                        mutex_unlock(&mhi_cntrl->pm_mutex);
                        return;
                }

                /*
                 * Device will clear BHI_INTVEC as a part of RESET processing,
                 * hence re-program it
                 */
                mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
        }

        dev_dbg(dev,
                 "Waiting for all pending event ring processing to complete\n");
        mhi_event = mhi_cntrl->mhi_event;
        for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
                if (mhi_event->offload_ev)
                        continue;
                tasklet_kill(&mhi_event->task);
        }

        /* Release lock and wait for all pending threads to complete */
        mutex_unlock(&mhi_cntrl->pm_mutex);
        dev_dbg(dev, "Waiting for all pending threads to complete\n");
        wake_up_all(&mhi_cntrl->state_event);

        dev_dbg(dev, "Reset all active channels and remove MHI devices\n");
        device_for_each_child(mhi_cntrl->cntrl_dev, NULL, mhi_destroy_device);

        mutex_lock(&mhi_cntrl->pm_mutex);

        WARN_ON(atomic_read(&mhi_cntrl->dev_wake));
        WARN_ON(atomic_read(&mhi_cntrl->pending_pkts));

        /* Reset the ev rings and cmd rings */
        dev_dbg(dev, "Resetting EV CTXT and CMD CTXT\n");
        mhi_cmd = mhi_cntrl->mhi_cmd;
        cmd_ctxt = mhi_cntrl->mhi_ctxt->cmd_ctxt;
        for (i = 0; i < NR_OF_CMD_RINGS; i++, mhi_cmd++, cmd_ctxt++) {
                struct mhi_ring *ring = &mhi_cmd->ring;

                ring->rp = ring->base;
                ring->wp = ring->base;
                cmd_ctxt->rp = cmd_ctxt->rbase;
                cmd_ctxt->wp = cmd_ctxt->rbase;
        }

        mhi_event = mhi_cntrl->mhi_event;
        er_ctxt = mhi_cntrl->mhi_ctxt->er_ctxt;
        for (i = 0; i < mhi_cntrl->total_ev_rings; i++, er_ctxt++,
                     mhi_event++) {
                struct mhi_ring *ring = &mhi_event->ring;

                /* Skip offload events */
                if (mhi_event->offload_ev)
                        continue;

                ring->rp = ring->base;
                ring->wp = ring->base;
                er_ctxt->rp = er_ctxt->rbase;
                er_ctxt->wp = er_ctxt->rbase;
        }

        if (cur_state == MHI_PM_SYS_ERR_PROCESS) {
                mhi_ready_state_transition(mhi_cntrl);
        } else {
                /* Move to disable state */
                write_lock_irq(&mhi_cntrl->pm_lock);
                cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_DISABLE);
                write_unlock_irq(&mhi_cntrl->pm_lock);
                if (unlikely(cur_state != MHI_PM_DISABLE))
                        dev_err(dev, "Error moving from PM state: %s to: %s\n",
                                to_mhi_pm_state_str(cur_state),
                                to_mhi_pm_state_str(MHI_PM_DISABLE));
        }

        dev_dbg(dev, "Exiting with PM state: %s, MHI state: %s\n",
                to_mhi_pm_state_str(mhi_cntrl->pm_state),
                TO_MHI_STATE_STR(mhi_cntrl->dev_state));

        mutex_unlock(&mhi_cntrl->pm_mutex);
}

/* Queue a new work item and schedule work */
int mhi_queue_state_transition(struct mhi_controller *mhi_cntrl,
                               enum dev_st_transition state)
{
        struct state_transition *item = kmalloc(sizeof(*item), GFP_ATOMIC);
        unsigned long flags;

        if (!item)
                return -ENOMEM;

        item->state = state;
        spin_lock_irqsave(&mhi_cntrl->transition_lock, flags);
        list_add_tail(&item->node, &mhi_cntrl->transition_list);
        spin_unlock_irqrestore(&mhi_cntrl->transition_lock, flags);

        schedule_work(&mhi_cntrl->st_worker);

        return 0;
}

/* SYS_ERR worker */
void mhi_pm_sys_err_handler(struct mhi_controller *mhi_cntrl)
{
        struct device *dev = &mhi_cntrl->mhi_dev->dev;

        /* skip if controller supports RDDM */
        if (mhi_cntrl->rddm_image) {
                dev_dbg(dev, "Controller supports RDDM, skip SYS_ERROR\n");
                return;
        }

        mhi_queue_state_transition(mhi_cntrl, DEV_ST_TRANSITION_SYS_ERR);
}

/* Device State Transition worker */
void mhi_pm_st_worker(struct work_struct *work)
{
        struct state_transition *itr, *tmp;
        LIST_HEAD(head);
        struct mhi_controller *mhi_cntrl = container_of(work,
                                                        struct mhi_controller,
                                                        st_worker);
        struct device *dev = &mhi_cntrl->mhi_dev->dev;

        spin_lock_irq(&mhi_cntrl->transition_lock);
        list_splice_tail_init(&mhi_cntrl->transition_list, &head);
        spin_unlock_irq(&mhi_cntrl->transition_lock);

        list_for_each_entry_safe(itr, tmp, &head, node) {
                list_del(&itr->node);
                dev_dbg(dev, "Handling state transition: %s\n",
                        TO_DEV_STATE_TRANS_STR(itr->state));

                switch (itr->state) {
                case DEV_ST_TRANSITION_PBL:
                        write_lock_irq(&mhi_cntrl->pm_lock);
                        if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state))
                                mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
                        write_unlock_irq(&mhi_cntrl->pm_lock);
                        if (MHI_IN_PBL(mhi_cntrl->ee))
                                mhi_fw_load_handler(mhi_cntrl);
                        break;
                case DEV_ST_TRANSITION_SBL:
                        write_lock_irq(&mhi_cntrl->pm_lock);
                        mhi_cntrl->ee = MHI_EE_SBL;
                        write_unlock_irq(&mhi_cntrl->pm_lock);
                        /*
                         * The MHI devices are only created when the client
                         * device switches its Execution Environment (EE) to
                         * either SBL or AMSS states
                         */
                        mhi_create_devices(mhi_cntrl);
                        break;
                case DEV_ST_TRANSITION_MISSION_MODE:
                        mhi_pm_mission_mode_transition(mhi_cntrl);
                        break;
                case DEV_ST_TRANSITION_READY:
                        mhi_ready_state_transition(mhi_cntrl);
                        break;
                case DEV_ST_TRANSITION_SYS_ERR:
                        mhi_pm_disable_transition
                                (mhi_cntrl, MHI_PM_SYS_ERR_PROCESS);
                        break;
                case DEV_ST_TRANSITION_DISABLE:
                        mhi_pm_disable_transition
                                (mhi_cntrl, MHI_PM_SHUTDOWN_PROCESS);
                        break;
                default:
                        break;
                }
                kfree(itr);
        }
}

int mhi_pm_suspend(struct mhi_controller *mhi_cntrl)
{
        struct mhi_chan *itr, *tmp;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        enum mhi_pm_state new_state;
        int ret;

        if (mhi_cntrl->pm_state == MHI_PM_DISABLE)
                return -EINVAL;

        if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))
                return -EIO;

        /* Return busy if there are any pending resources */
        if (atomic_read(&mhi_cntrl->dev_wake))
                return -EBUSY;

        /* Take MHI out of M2 state */
        read_lock_bh(&mhi_cntrl->pm_lock);
        mhi_cntrl->wake_get(mhi_cntrl, false);
        read_unlock_bh(&mhi_cntrl->pm_lock);

        ret = wait_event_timeout(mhi_cntrl->state_event,
                                 mhi_cntrl->dev_state == MHI_STATE_M0 ||
                                 mhi_cntrl->dev_state == MHI_STATE_M1 ||
                                 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
                                 msecs_to_jiffies(mhi_cntrl->timeout_ms));

        read_lock_bh(&mhi_cntrl->pm_lock);
        mhi_cntrl->wake_put(mhi_cntrl, false);
        read_unlock_bh(&mhi_cntrl->pm_lock);

        if (!ret || MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
                dev_err(dev,
                        "Could not enter M0/M1 state");
                return -EIO;
        }

        write_lock_irq(&mhi_cntrl->pm_lock);

        if (atomic_read(&mhi_cntrl->dev_wake)) {
                write_unlock_irq(&mhi_cntrl->pm_lock);
                return -EBUSY;
        }

        dev_info(dev, "Allowing M3 transition\n");
        new_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M3_ENTER);
        if (new_state != MHI_PM_M3_ENTER) {
                write_unlock_irq(&mhi_cntrl->pm_lock);
                dev_err(dev,
                        "Error setting to PM state: %s from: %s\n",
                        to_mhi_pm_state_str(MHI_PM_M3_ENTER),
                        to_mhi_pm_state_str(mhi_cntrl->pm_state));
                return -EIO;
        }

        /* Set MHI to M3 and wait for completion */
        mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
        write_unlock_irq(&mhi_cntrl->pm_lock);
        dev_info(dev, "Wait for M3 completion\n");

        ret = wait_event_timeout(mhi_cntrl->state_event,
                                 mhi_cntrl->dev_state == MHI_STATE_M3 ||
                                 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
                                 msecs_to_jiffies(mhi_cntrl->timeout_ms));

        if (!ret || MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
                dev_err(dev,
                        "Did not enter M3 state, MHI state: %s, PM state: %s\n",
                        TO_MHI_STATE_STR(mhi_cntrl->dev_state),
                        to_mhi_pm_state_str(mhi_cntrl->pm_state));
                return -EIO;
        }

        /* Notify clients about entering LPM */
        list_for_each_entry_safe(itr, tmp, &mhi_cntrl->lpm_chans, node) {
                mutex_lock(&itr->mutex);
                if (itr->mhi_dev)
                        mhi_notify(itr->mhi_dev, MHI_CB_LPM_ENTER);
                mutex_unlock(&itr->mutex);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(mhi_pm_suspend);

int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
{
        struct mhi_chan *itr, *tmp;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        enum mhi_pm_state cur_state;
        int ret;

        dev_info(dev, "Entered with PM state: %s, MHI state: %s\n",
                 to_mhi_pm_state_str(mhi_cntrl->pm_state),
                 TO_MHI_STATE_STR(mhi_cntrl->dev_state));

        if (mhi_cntrl->pm_state == MHI_PM_DISABLE)
                return 0;

        if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))
                return -EIO;

        /* Notify clients about exiting LPM */
        list_for_each_entry_safe(itr, tmp, &mhi_cntrl->lpm_chans, node) {
                mutex_lock(&itr->mutex);
                if (itr->mhi_dev)
                        mhi_notify(itr->mhi_dev, MHI_CB_LPM_EXIT);
                mutex_unlock(&itr->mutex);
        }

        write_lock_irq(&mhi_cntrl->pm_lock);
        cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M3_EXIT);
        if (cur_state != MHI_PM_M3_EXIT) {
                write_unlock_irq(&mhi_cntrl->pm_lock);
                dev_info(dev,
                         "Error setting to PM state: %s from: %s\n",
                         to_mhi_pm_state_str(MHI_PM_M3_EXIT),
                         to_mhi_pm_state_str(mhi_cntrl->pm_state));
                return -EIO;
        }

        /* Set MHI to M0 and wait for completion */
        mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
        write_unlock_irq(&mhi_cntrl->pm_lock);

        ret = wait_event_timeout(mhi_cntrl->state_event,
                                 mhi_cntrl->dev_state == MHI_STATE_M0 ||
                                 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
                                 msecs_to_jiffies(mhi_cntrl->timeout_ms));

        if (!ret || MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
                dev_err(dev,
                        "Did not enter M0 state, MHI state: %s, PM state: %s\n",
                        TO_MHI_STATE_STR(mhi_cntrl->dev_state),
                        to_mhi_pm_state_str(mhi_cntrl->pm_state));
                return -EIO;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(mhi_pm_resume);

int __mhi_device_get_sync(struct mhi_controller *mhi_cntrl)
{
        int ret;

        /* Wake up the device */
        read_lock_bh(&mhi_cntrl->pm_lock);
        mhi_cntrl->wake_get(mhi_cntrl, true);
        if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state)) {
                pm_wakeup_event(&mhi_cntrl->mhi_dev->dev, 0);
                mhi_cntrl->runtime_get(mhi_cntrl);
                mhi_cntrl->runtime_put(mhi_cntrl);
        }
        read_unlock_bh(&mhi_cntrl->pm_lock);

        ret = wait_event_timeout(mhi_cntrl->state_event,
                                 mhi_cntrl->pm_state == MHI_PM_M0 ||
                                 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
                                 msecs_to_jiffies(mhi_cntrl->timeout_ms));

        if (!ret || MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
                read_lock_bh(&mhi_cntrl->pm_lock);
                mhi_cntrl->wake_put(mhi_cntrl, false);
                read_unlock_bh(&mhi_cntrl->pm_lock);
                return -EIO;
        }

        return 0;
}

/* Assert device wake db */
static void mhi_assert_dev_wake(struct mhi_controller *mhi_cntrl, bool force)
{
        unsigned long flags;

        /*
         * If force flag is set, then increment the wake count value and
         * ring wake db
         */
        if (unlikely(force)) {
                spin_lock_irqsave(&mhi_cntrl->wlock, flags);
                atomic_inc(&mhi_cntrl->dev_wake);
                if (MHI_WAKE_DB_FORCE_SET_VALID(mhi_cntrl->pm_state) &&
                    !mhi_cntrl->wake_set) {
                        mhi_write_db(mhi_cntrl, mhi_cntrl->wake_db, 1);
                        mhi_cntrl->wake_set = true;
                }
                spin_unlock_irqrestore(&mhi_cntrl->wlock, flags);
        } else {
                /*
                 * If resources are already requested, then just increment
                 * the wake count value and return
                 */
                if (likely(atomic_add_unless(&mhi_cntrl->dev_wake, 1, 0)))
                        return;

                spin_lock_irqsave(&mhi_cntrl->wlock, flags);
                if ((atomic_inc_return(&mhi_cntrl->dev_wake) == 1) &&
                    MHI_WAKE_DB_SET_VALID(mhi_cntrl->pm_state) &&
                    !mhi_cntrl->wake_set) {
                        mhi_write_db(mhi_cntrl, mhi_cntrl->wake_db, 1);
                        mhi_cntrl->wake_set = true;
                }
                spin_unlock_irqrestore(&mhi_cntrl->wlock, flags);
        }
}

/* De-assert device wake db */
static void mhi_deassert_dev_wake(struct mhi_controller *mhi_cntrl,
                                  bool override)
{
        unsigned long flags;

        /*
         * Only continue if there is a single resource, else just decrement
         * and return
         */
        if (likely(atomic_add_unless(&mhi_cntrl->dev_wake, -1, 1)))
                return;

        spin_lock_irqsave(&mhi_cntrl->wlock, flags);
        if ((atomic_dec_return(&mhi_cntrl->dev_wake) == 0) &&
            MHI_WAKE_DB_CLEAR_VALID(mhi_cntrl->pm_state) && !override &&
            mhi_cntrl->wake_set) {
                mhi_write_db(mhi_cntrl, mhi_cntrl->wake_db, 0);
                mhi_cntrl->wake_set = false;
        }
        spin_unlock_irqrestore(&mhi_cntrl->wlock, flags);
}

int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
{
        enum mhi_state state;
        enum mhi_ee_type current_ee;
        enum dev_st_transition next_state;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        u32 val;
        int ret;

        dev_info(dev, "Requested to power ON\n");

        if (mhi_cntrl->nr_irqs < mhi_cntrl->total_ev_rings)
                return -EINVAL;

        /* Supply default wake routines if not provided by controller driver */
        if (!mhi_cntrl->wake_get || !mhi_cntrl->wake_put ||
            !mhi_cntrl->wake_toggle) {
                mhi_cntrl->wake_get = mhi_assert_dev_wake;
                mhi_cntrl->wake_put = mhi_deassert_dev_wake;
                mhi_cntrl->wake_toggle = (mhi_cntrl->db_access & MHI_PM_M2) ?
                        mhi_toggle_dev_wake_nop : mhi_toggle_dev_wake;
        }

        mutex_lock(&mhi_cntrl->pm_mutex);
        mhi_cntrl->pm_state = MHI_PM_DISABLE;

        if (!mhi_cntrl->pre_init) {
                /* Setup device context */
                ret = mhi_init_dev_ctxt(mhi_cntrl);
                if (ret)
                        goto error_dev_ctxt;
        }

        ret = mhi_init_irq_setup(mhi_cntrl);
        if (ret)
                goto error_setup_irq;

        /* Setup BHI offset & INTVEC */
        write_lock_irq(&mhi_cntrl->pm_lock);
        ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->regs, BHIOFF, &val);
        if (ret) {
                write_unlock_irq(&mhi_cntrl->pm_lock);
                goto error_bhi_offset;
        }

        mhi_cntrl->bhi = mhi_cntrl->regs + val;

        /* Setup BHIE offset */
        if (mhi_cntrl->fbc_download) {
                ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->regs, BHIEOFF, &val);
                if (ret) {
                        write_unlock_irq(&mhi_cntrl->pm_lock);
                        dev_err(dev, "Error reading BHIE offset\n");
                        goto error_bhi_offset;
                }

                mhi_cntrl->bhie = mhi_cntrl->regs + val;
        }

        mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
        mhi_cntrl->pm_state = MHI_PM_POR;
        mhi_cntrl->ee = MHI_EE_MAX;
        current_ee = mhi_get_exec_env(mhi_cntrl);
        write_unlock_irq(&mhi_cntrl->pm_lock);

        /* Confirm that the device is in valid exec env */
        if (!MHI_IN_PBL(current_ee) && current_ee != MHI_EE_AMSS) {
                dev_err(dev, "Not a valid EE for power on\n");
                ret = -EIO;
                goto error_bhi_offset;
        }

        state = mhi_get_mhi_state(mhi_cntrl);
        if (state == MHI_STATE_SYS_ERR) {
                mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
                ret = wait_event_timeout(mhi_cntrl->state_event,
                                MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
                                        mhi_read_reg_field(mhi_cntrl,
                                                           mhi_cntrl->regs,
                                                           MHICTRL,
                                                           MHICTRL_RESET_MASK,
                                                           MHICTRL_RESET_SHIFT,
                                                           &val) ||
                                        !val,
                                msecs_to_jiffies(mhi_cntrl->timeout_ms));
                if (ret) {
                        ret = -EIO;
                        dev_info(dev, "Failed to reset MHI due to syserr state\n");
                        goto error_bhi_offset;
                }

                /*
                 * device cleares INTVEC as part of RESET processing,
                 * re-program it

                 */
                mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
        }

        /* Transition to next state */
        next_state = MHI_IN_PBL(current_ee) ?
                DEV_ST_TRANSITION_PBL : DEV_ST_TRANSITION_READY;

        mhi_queue_state_transition(mhi_cntrl, next_state);

        mutex_unlock(&mhi_cntrl->pm_mutex);

        dev_info(dev, "Power on setup success\n");

        return 0;

error_bhi_offset:
        mhi_deinit_free_irq(mhi_cntrl);

error_setup_irq:
        if (!mhi_cntrl->pre_init)
                mhi_deinit_dev_ctxt(mhi_cntrl);

error_dev_ctxt:
        mutex_unlock(&mhi_cntrl->pm_mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(mhi_async_power_up);

void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
{
        enum mhi_pm_state cur_state;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;

        /* If it's not a graceful shutdown, force MHI to linkdown state */
        if (!graceful) {
                mutex_lock(&mhi_cntrl->pm_mutex);
                write_lock_irq(&mhi_cntrl->pm_lock);
                cur_state = mhi_tryset_pm_state(mhi_cntrl,
                                                MHI_PM_LD_ERR_FATAL_DETECT);
                write_unlock_irq(&mhi_cntrl->pm_lock);
                mutex_unlock(&mhi_cntrl->pm_mutex);
                if (cur_state != MHI_PM_LD_ERR_FATAL_DETECT)
                        dev_dbg(dev, "Failed to move to state: %s from: %s\n",
                                to_mhi_pm_state_str(MHI_PM_LD_ERR_FATAL_DETECT),
                                to_mhi_pm_state_str(mhi_cntrl->pm_state));
        }

        mhi_queue_state_transition(mhi_cntrl, DEV_ST_TRANSITION_DISABLE);

        /* Wait for shutdown to complete */
        flush_work(&mhi_cntrl->st_worker);

        mhi_deinit_free_irq(mhi_cntrl);

        if (!mhi_cntrl->pre_init) {
                /* Free all allocated resources */
                if (mhi_cntrl->fbc_image) {
                        mhi_free_bhie_table(mhi_cntrl, mhi_cntrl->fbc_image);
                        mhi_cntrl->fbc_image = NULL;
                }
                mhi_deinit_dev_ctxt(mhi_cntrl);
        }
}
EXPORT_SYMBOL_GPL(mhi_power_down);

int mhi_sync_power_up(struct mhi_controller *mhi_cntrl)
{
        int ret = mhi_async_power_up(mhi_cntrl);

        if (ret)
                return ret;

        wait_event_timeout(mhi_cntrl->state_event,
                           MHI_IN_MISSION_MODE(mhi_cntrl->ee) ||
                           MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
                           msecs_to_jiffies(mhi_cntrl->timeout_ms));

        ret = (MHI_IN_MISSION_MODE(mhi_cntrl->ee)) ? 0 : -ETIMEDOUT;
        if (ret)
                mhi_power_down(mhi_cntrl, false);

        return ret;
}
EXPORT_SYMBOL(mhi_sync_power_up);

int mhi_force_rddm_mode(struct mhi_controller *mhi_cntrl)
{
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        int ret;

        /* Check if device is already in RDDM */
        if (mhi_cntrl->ee == MHI_EE_RDDM)
                return 0;

        dev_dbg(dev, "Triggering SYS_ERR to force RDDM state\n");
        mhi_set_mhi_state(mhi_cntrl, MHI_STATE_SYS_ERR);

        /* Wait for RDDM event */
        ret = wait_event_timeout(mhi_cntrl->state_event,
                                 mhi_cntrl->ee == MHI_EE_RDDM,
                                 msecs_to_jiffies(mhi_cntrl->timeout_ms));
        ret = ret ? 0 : -EIO;

        return ret;
}
EXPORT_SYMBOL_GPL(mhi_force_rddm_mode);

void mhi_device_get(struct mhi_device *mhi_dev)
{
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

        mhi_dev->dev_wake++;
        read_lock_bh(&mhi_cntrl->pm_lock);
        mhi_cntrl->wake_get(mhi_cntrl, true);
        read_unlock_bh(&mhi_cntrl->pm_lock);
}
EXPORT_SYMBOL_GPL(mhi_device_get);

int mhi_device_get_sync(struct mhi_device *mhi_dev)
{
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
        int ret;

        ret = __mhi_device_get_sync(mhi_cntrl);
        if (!ret)
                mhi_dev->dev_wake++;

        return ret;
}
EXPORT_SYMBOL_GPL(mhi_device_get_sync);

void mhi_device_put(struct mhi_device *mhi_dev)
{
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

        mhi_dev->dev_wake--;
        read_lock_bh(&mhi_cntrl->pm_lock);
        if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state)) {
                mhi_cntrl->runtime_get(mhi_cntrl);
                mhi_cntrl->runtime_put(mhi_cntrl);
        }

        mhi_cntrl->wake_put(mhi_cntrl, false);
        read_unlock_bh(&mhi_cntrl->pm_lock);
}
EXPORT_SYMBOL_GPL(mhi_device_put);