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

#include <linux/bitfield.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
#include <linux/idr.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/mhi.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>
#include "internal.h"

#define CREATE_TRACE_POINTS
#include "trace.h"

static DEFINE_IDA(mhi_controller_ida);

#undef mhi_ee
#undef mhi_ee_end

#define mhi_ee(a, b)            [MHI_EE_##a] = b,
#define mhi_ee_end(a, b)        [MHI_EE_##a] = b,

const char * const mhi_ee_str[MHI_EE_MAX] = {
        MHI_EE_LIST
};

#undef dev_st_trans
#undef dev_st_trans_end

#define dev_st_trans(a, b)      [DEV_ST_TRANSITION_##a] = b,
#define dev_st_trans_end(a, b)  [DEV_ST_TRANSITION_##a] = b,

const char * const dev_state_tran_str[DEV_ST_TRANSITION_MAX] = {
        DEV_ST_TRANSITION_LIST
};

#undef ch_state_type
#undef ch_state_type_end

#define ch_state_type(a, b)     [MHI_CH_STATE_TYPE_##a] = b,
#define ch_state_type_end(a, b) [MHI_CH_STATE_TYPE_##a] = b,

const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX] = {
        MHI_CH_STATE_TYPE_LIST
};

#undef mhi_pm_state
#undef mhi_pm_state_end

#define mhi_pm_state(a, b)      [MHI_PM_STATE_##a] = b,
#define mhi_pm_state_end(a, b)  [MHI_PM_STATE_##a] = b,

static const char * const mhi_pm_state_str[] = {
        MHI_PM_STATE_LIST
};

const char *to_mhi_pm_state_str(u32 state)
{
        int index;

        if (state)
                index = __fls(state);

        if (!state || index >= ARRAY_SIZE(mhi_pm_state_str))
                return "Invalid State";

        return mhi_pm_state_str[index];
}

static ssize_t serial_number_show(struct device *dev,
                                  struct device_attribute *attr,
                                  char *buf)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

        return sysfs_emit(buf, "Serial Number: %u\n",
                        mhi_cntrl->serial_number);
}
static DEVICE_ATTR_RO(serial_number);

static ssize_t oem_pk_hash_show(struct device *dev,
                                struct device_attribute *attr,
                                char *buf)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
        u32 hash_segment[MHI_MAX_OEM_PK_HASH_SEGMENTS];
        int i, cnt = 0, ret;

        for (i = 0; i < MHI_MAX_OEM_PK_HASH_SEGMENTS; i++) {
                ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_OEMPKHASH(i), &hash_segment[i]);
                if (ret) {
                        dev_err(dev, "Could not capture OEM PK HASH\n");
                        return ret;
                }
        }

        for (i = 0; i < MHI_MAX_OEM_PK_HASH_SEGMENTS; i++)
                cnt += sysfs_emit_at(buf, cnt, "OEMPKHASH[%d]: 0x%x\n", i, hash_segment[i]);

        return cnt;
}
static DEVICE_ATTR_RO(oem_pk_hash);

static ssize_t soc_reset_store(struct device *dev,
                               struct device_attribute *attr,
                               const char *buf,
                               size_t count)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

        mhi_soc_reset(mhi_cntrl);
        return count;
}
static DEVICE_ATTR_WO(soc_reset);

static ssize_t trigger_edl_store(struct device *dev,
                               struct device_attribute *attr,
                               const char *buf, size_t count)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
        unsigned long val;
        int ret;

        ret = kstrtoul(buf, 10, &val);
        if (ret < 0)
                return ret;

        if (!val)
                return -EINVAL;

        ret = mhi_cntrl->edl_trigger(mhi_cntrl);
        if (ret)
                return ret;

        return count;
}
static DEVICE_ATTR_WO(trigger_edl);

static struct attribute *mhi_dev_attrs[] = {
        &dev_attr_serial_number.attr,
        &dev_attr_oem_pk_hash.attr,
        &dev_attr_soc_reset.attr,
        NULL,
};
ATTRIBUTE_GROUPS(mhi_dev);

/* MHI protocol requires the transfer ring to be aligned with ring length */
static int mhi_alloc_aligned_ring(struct mhi_controller *mhi_cntrl,
                                  struct mhi_ring *ring,
                                  u64 len)
{
        ring->alloc_size = len + (len - 1);
        ring->pre_aligned = dma_alloc_coherent(mhi_cntrl->cntrl_dev, ring->alloc_size,
                                               &ring->dma_handle, GFP_KERNEL);
        if (!ring->pre_aligned)
                return -ENOMEM;

        ring->iommu_base = (ring->dma_handle + (len - 1)) & ~(len - 1);
        ring->base = ring->pre_aligned + (ring->iommu_base - ring->dma_handle);

        return 0;
}

static void mhi_deinit_free_irq(struct mhi_controller *mhi_cntrl)
{
        int i;
        struct mhi_event *mhi_event = mhi_cntrl->mhi_event;

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

                free_irq(mhi_cntrl->irq[mhi_event->irq], mhi_event);
        }

        free_irq(mhi_cntrl->irq[0], mhi_cntrl);
}

static int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl)
{
        struct mhi_event *mhi_event = mhi_cntrl->mhi_event;
        unsigned long irq_flags = IRQF_SHARED | IRQF_NO_SUSPEND;
        int i, ret;

        /* if controller driver has set irq_flags, use it */
        if (mhi_cntrl->irq_flags)
                irq_flags = mhi_cntrl->irq_flags;

        /* Setup BHI_INTVEC IRQ */
        ret = request_threaded_irq(mhi_cntrl->irq[0], mhi_intvec_handler,
                                   mhi_intvec_threaded_handler,
                                   irq_flags,
                                   "bhi", mhi_cntrl);
        if (ret)
                return ret;
        /*
         * IRQs should be enabled during mhi_async_power_up(), so disable them explicitly here.
         * Due to the use of IRQF_SHARED flag as default while requesting IRQs, we assume that
         * IRQ_NOAUTOEN is not applicable.
         */
        disable_irq(mhi_cntrl->irq[0]);

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

                if (mhi_event->irq >= mhi_cntrl->nr_irqs) {
                        dev_err(mhi_cntrl->cntrl_dev, "irq %d not available for event ring\n",
                                mhi_event->irq);
                        ret = -EINVAL;
                        goto error_request;
                }

                ret = request_irq(mhi_cntrl->irq[mhi_event->irq],
                                  mhi_irq_handler,
                                  irq_flags,
                                  "mhi", mhi_event);
                if (ret) {
                        dev_err(mhi_cntrl->cntrl_dev, "Error requesting irq:%d for ev:%d\n",
                                mhi_cntrl->irq[mhi_event->irq], i);
                        goto error_request;
                }

                disable_irq(mhi_cntrl->irq[mhi_event->irq]);
        }

        return 0;

error_request:
        for (--i, --mhi_event; i >= 0; i--, mhi_event--) {
                if (mhi_event->offload_ev)
                        continue;

                free_irq(mhi_cntrl->irq[mhi_event->irq], mhi_event);
        }
        free_irq(mhi_cntrl->irq[0], mhi_cntrl);

        return ret;
}

static void mhi_deinit_dev_ctxt(struct mhi_controller *mhi_cntrl)
{
        int i;
        struct mhi_ctxt *mhi_ctxt = mhi_cntrl->mhi_ctxt;
        struct mhi_cmd *mhi_cmd;
        struct mhi_event *mhi_event;
        struct mhi_ring *ring;

        mhi_cmd = mhi_cntrl->mhi_cmd;
        for (i = 0; i < NR_OF_CMD_RINGS; i++, mhi_cmd++) {
                ring = &mhi_cmd->ring;
                dma_free_coherent(mhi_cntrl->cntrl_dev, ring->alloc_size,
                                  ring->pre_aligned, ring->dma_handle);
                ring->base = NULL;
                ring->iommu_base = 0;
        }

        dma_free_coherent(mhi_cntrl->cntrl_dev,
                          sizeof(*mhi_ctxt->cmd_ctxt) * NR_OF_CMD_RINGS,
                          mhi_ctxt->cmd_ctxt, mhi_ctxt->cmd_ctxt_addr);

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

                ring = &mhi_event->ring;
                dma_free_coherent(mhi_cntrl->cntrl_dev, ring->alloc_size,
                                  ring->pre_aligned, ring->dma_handle);
                ring->base = NULL;
                ring->iommu_base = 0;
        }

        dma_free_coherent(mhi_cntrl->cntrl_dev, sizeof(*mhi_ctxt->er_ctxt) *
                          mhi_cntrl->total_ev_rings, mhi_ctxt->er_ctxt,
                          mhi_ctxt->er_ctxt_addr);

        dma_free_coherent(mhi_cntrl->cntrl_dev, sizeof(*mhi_ctxt->chan_ctxt) *
                          mhi_cntrl->max_chan, mhi_ctxt->chan_ctxt,
                          mhi_ctxt->chan_ctxt_addr);

        kfree(mhi_ctxt);
        mhi_cntrl->mhi_ctxt = NULL;
}

static int mhi_init_dev_ctxt(struct mhi_controller *mhi_cntrl)
{
        struct mhi_ctxt *mhi_ctxt;
        struct mhi_chan_ctxt *chan_ctxt;
        struct mhi_event_ctxt *er_ctxt;
        struct mhi_cmd_ctxt *cmd_ctxt;
        struct mhi_chan *mhi_chan;
        struct mhi_event *mhi_event;
        struct mhi_cmd *mhi_cmd;
        u32 tmp;
        int ret = -ENOMEM, i;

        atomic_set(&mhi_cntrl->dev_wake, 0);
        atomic_set(&mhi_cntrl->pending_pkts, 0);

        mhi_ctxt = kzalloc_obj(*mhi_ctxt);
        if (!mhi_ctxt)
                return -ENOMEM;

        /* Setup channel ctxt */
        mhi_ctxt->chan_ctxt = dma_alloc_coherent(mhi_cntrl->cntrl_dev,
                                                 sizeof(*mhi_ctxt->chan_ctxt) *
                                                 mhi_cntrl->max_chan,
                                                 &mhi_ctxt->chan_ctxt_addr,
                                                 GFP_KERNEL);
        if (!mhi_ctxt->chan_ctxt)
                goto error_alloc_chan_ctxt;

        mhi_chan = mhi_cntrl->mhi_chan;
        chan_ctxt = mhi_ctxt->chan_ctxt;
        for (i = 0; i < mhi_cntrl->max_chan; i++, chan_ctxt++, mhi_chan++) {
                /* Skip if it is an offload channel */
                if (mhi_chan->offload_ch)
                        continue;

                tmp = le32_to_cpu(chan_ctxt->chcfg);
                tmp &= ~CHAN_CTX_CHSTATE_MASK;
                tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_DISABLED);
                tmp &= ~CHAN_CTX_BRSTMODE_MASK;
                tmp |= FIELD_PREP(CHAN_CTX_BRSTMODE_MASK, mhi_chan->db_cfg.brstmode);
                tmp &= ~CHAN_CTX_POLLCFG_MASK;
                tmp |= FIELD_PREP(CHAN_CTX_POLLCFG_MASK, mhi_chan->db_cfg.pollcfg);
                chan_ctxt->chcfg = cpu_to_le32(tmp);

                chan_ctxt->chtype = cpu_to_le32(mhi_chan->type);
                chan_ctxt->erindex = cpu_to_le32(mhi_chan->er_index);

                mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
                mhi_chan->tre_ring.db_addr = (void __iomem *)&chan_ctxt->wp;
        }

        /* Setup event context */
        mhi_ctxt->er_ctxt = dma_alloc_coherent(mhi_cntrl->cntrl_dev,
                                               sizeof(*mhi_ctxt->er_ctxt) *
                                               mhi_cntrl->total_ev_rings,
                                               &mhi_ctxt->er_ctxt_addr,
                                               GFP_KERNEL);
        if (!mhi_ctxt->er_ctxt)
                goto error_alloc_er_ctxt;

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

                /* Skip if it is an offload event */
                if (mhi_event->offload_ev)
                        continue;

                tmp = le32_to_cpu(er_ctxt->intmod);
                tmp &= ~EV_CTX_INTMODC_MASK;
                tmp &= ~EV_CTX_INTMODT_MASK;
                tmp |= FIELD_PREP(EV_CTX_INTMODT_MASK, mhi_event->intmod);
                er_ctxt->intmod = cpu_to_le32(tmp);

                er_ctxt->ertype = cpu_to_le32(MHI_ER_TYPE_VALID);
                er_ctxt->msivec = cpu_to_le32(mhi_event->irq);
                mhi_event->db_cfg.db_mode = true;

                ring->el_size = sizeof(struct mhi_ring_element);
                ring->len = ring->el_size * ring->elements;
                ret = mhi_alloc_aligned_ring(mhi_cntrl, ring, ring->len);
                if (ret)
                        goto error_alloc_er;

                /*
                 * If the read pointer equals to the write pointer, then the
                 * ring is empty
                 */
                ring->rp = ring->wp = ring->base;
                er_ctxt->rbase = cpu_to_le64(ring->iommu_base);
                er_ctxt->rp = er_ctxt->wp = er_ctxt->rbase;
                er_ctxt->rlen = cpu_to_le64(ring->len);
                ring->ctxt_wp = &er_ctxt->wp;
        }

        /* Setup cmd context */
        ret = -ENOMEM;
        mhi_ctxt->cmd_ctxt = dma_alloc_coherent(mhi_cntrl->cntrl_dev,
                                                sizeof(*mhi_ctxt->cmd_ctxt) *
                                                NR_OF_CMD_RINGS,
                                                &mhi_ctxt->cmd_ctxt_addr,
                                                GFP_KERNEL);
        if (!mhi_ctxt->cmd_ctxt)
                goto error_alloc_er;

        mhi_cmd = mhi_cntrl->mhi_cmd;
        cmd_ctxt = 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->el_size = sizeof(struct mhi_ring_element);
                ring->elements = CMD_EL_PER_RING;
                ring->len = ring->el_size * ring->elements;
                ret = mhi_alloc_aligned_ring(mhi_cntrl, ring, ring->len);
                if (ret)
                        goto error_alloc_cmd;

                ring->rp = ring->wp = ring->base;
                cmd_ctxt->rbase = cpu_to_le64(ring->iommu_base);
                cmd_ctxt->rp = cmd_ctxt->wp = cmd_ctxt->rbase;
                cmd_ctxt->rlen = cpu_to_le64(ring->len);
                ring->ctxt_wp = &cmd_ctxt->wp;
        }

        mhi_cntrl->mhi_ctxt = mhi_ctxt;

        return 0;

error_alloc_cmd:
        for (--i, --mhi_cmd; i >= 0; i--, mhi_cmd--) {
                struct mhi_ring *ring = &mhi_cmd->ring;

                dma_free_coherent(mhi_cntrl->cntrl_dev, ring->alloc_size,
                                  ring->pre_aligned, ring->dma_handle);
        }
        dma_free_coherent(mhi_cntrl->cntrl_dev,
                          sizeof(*mhi_ctxt->cmd_ctxt) * NR_OF_CMD_RINGS,
                          mhi_ctxt->cmd_ctxt, mhi_ctxt->cmd_ctxt_addr);
        i = mhi_cntrl->total_ev_rings;
        mhi_event = mhi_cntrl->mhi_event + i;

error_alloc_er:
        for (--i, --mhi_event; i >= 0; i--, mhi_event--) {
                struct mhi_ring *ring = &mhi_event->ring;

                if (mhi_event->offload_ev)
                        continue;

                dma_free_coherent(mhi_cntrl->cntrl_dev, ring->alloc_size,
                                  ring->pre_aligned, ring->dma_handle);
        }
        dma_free_coherent(mhi_cntrl->cntrl_dev, sizeof(*mhi_ctxt->er_ctxt) *
                          mhi_cntrl->total_ev_rings, mhi_ctxt->er_ctxt,
                          mhi_ctxt->er_ctxt_addr);

error_alloc_er_ctxt:
        dma_free_coherent(mhi_cntrl->cntrl_dev, sizeof(*mhi_ctxt->chan_ctxt) *
                          mhi_cntrl->max_chan, mhi_ctxt->chan_ctxt,
                          mhi_ctxt->chan_ctxt_addr);

error_alloc_chan_ctxt:
        kfree(mhi_ctxt);

        return ret;
}

int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
{
        u32 val;
        int i, ret;
        struct mhi_chan *mhi_chan;
        struct mhi_event *mhi_event;
        void __iomem *base = mhi_cntrl->regs;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        struct {
                u32 offset;
                u32 val;
        } reg_info[] = {
                {
                        CCABAP_HIGHER,
                        upper_32_bits(mhi_cntrl->mhi_ctxt->chan_ctxt_addr),
                },
                {
                        CCABAP_LOWER,
                        lower_32_bits(mhi_cntrl->mhi_ctxt->chan_ctxt_addr),
                },
                {
                        ECABAP_HIGHER,
                        upper_32_bits(mhi_cntrl->mhi_ctxt->er_ctxt_addr),
                },
                {
                        ECABAP_LOWER,
                        lower_32_bits(mhi_cntrl->mhi_ctxt->er_ctxt_addr),
                },
                {
                        CRCBAP_HIGHER,
                        upper_32_bits(mhi_cntrl->mhi_ctxt->cmd_ctxt_addr),
                },
                {
                        CRCBAP_LOWER,
                        lower_32_bits(mhi_cntrl->mhi_ctxt->cmd_ctxt_addr),
                },
                {
                        MHICTRLBASE_HIGHER,
                        upper_32_bits(mhi_cntrl->iova_start),
                },
                {
                        MHICTRLBASE_LOWER,
                        lower_32_bits(mhi_cntrl->iova_start),
                },
                {
                        MHIDATABASE_HIGHER,
                        upper_32_bits(mhi_cntrl->iova_start),
                },
                {
                        MHIDATABASE_LOWER,
                        lower_32_bits(mhi_cntrl->iova_start),
                },
                {
                        MHICTRLLIMIT_HIGHER,
                        upper_32_bits(mhi_cntrl->iova_stop),
                },
                {
                        MHICTRLLIMIT_LOWER,
                        lower_32_bits(mhi_cntrl->iova_stop),
                },
                {
                        MHIDATALIMIT_HIGHER,
                        upper_32_bits(mhi_cntrl->iova_stop),
                },
                {
                        MHIDATALIMIT_LOWER,
                        lower_32_bits(mhi_cntrl->iova_stop),
                },
                {0, 0}
        };

        dev_dbg(dev, "Initializing MHI registers\n");

        /* Read channel db offset */
        ret = mhi_get_channel_doorbell_offset(mhi_cntrl, &val);
        if (ret)
                return ret;

        if (val >= mhi_cntrl->reg_len - (8 * MHI_DEV_WAKE_DB)) {
                dev_err(dev, "CHDB offset: 0x%x is out of range: 0x%zx\n",
                        val, mhi_cntrl->reg_len - (8 * MHI_DEV_WAKE_DB));
                return -ERANGE;
        }

        /* Setup wake db */
        mhi_cntrl->wake_db = base + val + (8 * MHI_DEV_WAKE_DB);
        mhi_cntrl->wake_set = false;

        /* Setup channel db address for each channel in tre_ring */
        mhi_chan = mhi_cntrl->mhi_chan;
        for (i = 0; i < mhi_cntrl->max_chan; i++, val += 8, mhi_chan++)
                mhi_chan->tre_ring.db_addr = base + val;

        /* Read event ring db offset */
        ret = mhi_read_reg(mhi_cntrl, base, ERDBOFF, &val);
        if (ret) {
                dev_err(dev, "Unable to read ERDBOFF register\n");
                return -EIO;
        }

        if (val >= mhi_cntrl->reg_len - (8 * mhi_cntrl->total_ev_rings)) {
                dev_err(dev, "ERDB offset: 0x%x is out of range: 0x%zx\n",
                        val, mhi_cntrl->reg_len - (8 * mhi_cntrl->total_ev_rings));
                return -ERANGE;
        }

        /* Setup event db address for each ev_ring */
        mhi_event = mhi_cntrl->mhi_event;
        for (i = 0; i < mhi_cntrl->total_ev_rings; i++, val += 8, mhi_event++) {
                if (mhi_event->offload_ev)
                        continue;

                mhi_event->ring.db_addr = base + val;
        }

        /* Setup DB register for primary CMD rings */
        mhi_cntrl->mhi_cmd[PRIMARY_CMD_RING].ring.db_addr = base + CRDB_LOWER;

        /* Write to MMIO registers */
        for (i = 0; reg_info[i].offset; i++)
                mhi_write_reg(mhi_cntrl, base, reg_info[i].offset,
                              reg_info[i].val);

        ret = mhi_write_reg_field(mhi_cntrl, base, MHICFG, MHICFG_NER_MASK,
                                  mhi_cntrl->total_ev_rings);
        if (ret) {
                dev_err(dev, "Unable to write MHICFG register\n");
                return ret;
        }

        ret = mhi_write_reg_field(mhi_cntrl, base, MHICFG, MHICFG_NHWER_MASK,
                                  mhi_cntrl->hw_ev_rings);
        if (ret) {
                dev_err(dev, "Unable to write MHICFG register\n");
                return ret;
        }

        return 0;
}

void mhi_deinit_chan_ctxt(struct mhi_controller *mhi_cntrl,
                          struct mhi_chan *mhi_chan)
{
        struct mhi_ring *buf_ring;
        struct mhi_ring *tre_ring;
        struct mhi_chan_ctxt *chan_ctxt;
        u32 tmp;

        buf_ring = &mhi_chan->buf_ring;
        tre_ring = &mhi_chan->tre_ring;
        chan_ctxt = &mhi_cntrl->mhi_ctxt->chan_ctxt[mhi_chan->chan];

        if (!chan_ctxt->rbase) /* Already uninitialized */
                return;

        dma_free_coherent(mhi_cntrl->cntrl_dev, tre_ring->alloc_size,
                          tre_ring->pre_aligned, tre_ring->dma_handle);
        vfree(buf_ring->base);

        buf_ring->base = tre_ring->base = NULL;
        tre_ring->ctxt_wp = NULL;
        chan_ctxt->rbase = 0;
        chan_ctxt->rlen = 0;
        chan_ctxt->rp = 0;
        chan_ctxt->wp = 0;

        tmp = le32_to_cpu(chan_ctxt->chcfg);
        tmp &= ~CHAN_CTX_CHSTATE_MASK;
        tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_DISABLED);
        chan_ctxt->chcfg = cpu_to_le32(tmp);

        /* Update to all cores */
        smp_wmb();
}

int mhi_init_chan_ctxt(struct mhi_controller *mhi_cntrl,
                       struct mhi_chan *mhi_chan)
{
        struct mhi_ring *buf_ring;
        struct mhi_ring *tre_ring;
        struct mhi_chan_ctxt *chan_ctxt;
        u32 tmp;
        int ret;

        buf_ring = &mhi_chan->buf_ring;
        tre_ring = &mhi_chan->tre_ring;
        tre_ring->el_size = sizeof(struct mhi_ring_element);
        tre_ring->len = tre_ring->el_size * tre_ring->elements;
        chan_ctxt = &mhi_cntrl->mhi_ctxt->chan_ctxt[mhi_chan->chan];
        ret = mhi_alloc_aligned_ring(mhi_cntrl, tre_ring, tre_ring->len);
        if (ret)
                return -ENOMEM;

        buf_ring->el_size = sizeof(struct mhi_buf_info);
        buf_ring->len = buf_ring->el_size * buf_ring->elements;
        buf_ring->base = vzalloc(buf_ring->len);

        if (!buf_ring->base) {
                dma_free_coherent(mhi_cntrl->cntrl_dev, tre_ring->alloc_size,
                                  tre_ring->pre_aligned, tre_ring->dma_handle);
                return -ENOMEM;
        }

        tmp = le32_to_cpu(chan_ctxt->chcfg);
        tmp &= ~CHAN_CTX_CHSTATE_MASK;
        tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_ENABLED);
        chan_ctxt->chcfg = cpu_to_le32(tmp);

        chan_ctxt->rbase = cpu_to_le64(tre_ring->iommu_base);
        chan_ctxt->rp = chan_ctxt->wp = chan_ctxt->rbase;
        chan_ctxt->rlen = cpu_to_le64(tre_ring->len);
        tre_ring->ctxt_wp = &chan_ctxt->wp;

        tre_ring->rp = tre_ring->wp = tre_ring->base;
        buf_ring->rp = buf_ring->wp = buf_ring->base;
        mhi_chan->db_cfg.db_mode = 1;

        /* Update to all cores */
        smp_wmb();

        return 0;
}

static int parse_ev_cfg(struct mhi_controller *mhi_cntrl,
                        const struct mhi_controller_config *config)
{
        struct mhi_event *mhi_event;
        const struct mhi_event_config *event_cfg;
        struct device *dev = mhi_cntrl->cntrl_dev;
        int i, num;

        num = config->num_events;
        mhi_cntrl->total_ev_rings = num;
        mhi_cntrl->mhi_event = kzalloc_objs(*mhi_cntrl->mhi_event, num);
        if (!mhi_cntrl->mhi_event)
                return -ENOMEM;

        /* Populate event ring */
        mhi_event = mhi_cntrl->mhi_event;
        for (i = 0; i < num; i++) {
                event_cfg = &config->event_cfg[i];

                mhi_event->er_index = i;
                mhi_event->ring.elements = event_cfg->num_elements;
                mhi_event->intmod = event_cfg->irq_moderation_ms;
                mhi_event->irq = event_cfg->irq;

                if (event_cfg->channel != U32_MAX) {
                        /* This event ring has a dedicated channel */
                        mhi_event->chan = event_cfg->channel;
                        if (mhi_event->chan >= mhi_cntrl->max_chan) {
                                dev_err(dev,
                                        "Event Ring channel not available\n");
                                goto error_ev_cfg;
                        }

                        mhi_event->mhi_chan =
                                &mhi_cntrl->mhi_chan[mhi_event->chan];
                }

                /* Priority is fixed to 1 for now */
                mhi_event->priority = 1;

                mhi_event->db_cfg.brstmode = event_cfg->mode;
                if (MHI_INVALID_BRSTMODE(mhi_event->db_cfg.brstmode))
                        goto error_ev_cfg;

                if (mhi_event->db_cfg.brstmode == MHI_DB_BRST_ENABLE)
                        mhi_event->db_cfg.process_db = mhi_db_brstmode;
                else
                        mhi_event->db_cfg.process_db = mhi_db_brstmode_disable;

                mhi_event->data_type = event_cfg->data_type;

                switch (mhi_event->data_type) {
                case MHI_ER_DATA:
                        mhi_event->process_event = mhi_process_data_event_ring;
                        break;
                case MHI_ER_CTRL:
                        mhi_event->process_event = mhi_process_ctrl_ev_ring;
                        break;
                default:
                        dev_err(dev, "Event Ring type not supported\n");
                        goto error_ev_cfg;
                }

                mhi_event->hw_ring = event_cfg->hardware_event;
                if (mhi_event->hw_ring)
                        mhi_cntrl->hw_ev_rings++;
                else
                        mhi_cntrl->sw_ev_rings++;

                mhi_event->cl_manage = event_cfg->client_managed;
                mhi_event->offload_ev = event_cfg->offload_channel;
                mhi_event++;
        }

        return 0;

error_ev_cfg:

        kfree(mhi_cntrl->mhi_event);
        return -EINVAL;
}

static int parse_ch_cfg(struct mhi_controller *mhi_cntrl,
                        const struct mhi_controller_config *config)
{
        const struct mhi_channel_config *ch_cfg;
        struct device *dev = mhi_cntrl->cntrl_dev;
        int i;
        u32 chan;

        mhi_cntrl->max_chan = config->max_channels;

        /*
         * The allocation of MHI channels can exceed 32KB in some scenarios,
         * so to avoid any memory possible allocation failures, vzalloc is
         * used here
         */
        mhi_cntrl->mhi_chan = vcalloc(mhi_cntrl->max_chan,
                                      sizeof(*mhi_cntrl->mhi_chan));
        if (!mhi_cntrl->mhi_chan)
                return -ENOMEM;

        INIT_LIST_HEAD(&mhi_cntrl->lpm_chans);

        /* Populate channel configurations */
        for (i = 0; i < config->num_channels; i++) {
                struct mhi_chan *mhi_chan;

                ch_cfg = &config->ch_cfg[i];

                chan = ch_cfg->num;
                if (chan >= mhi_cntrl->max_chan) {
                        dev_err(dev, "Channel %d not available\n", chan);
                        goto error_chan_cfg;
                }

                mhi_chan = &mhi_cntrl->mhi_chan[chan];
                mhi_chan->name = ch_cfg->name;
                mhi_chan->chan = chan;

                mhi_chan->tre_ring.elements = ch_cfg->num_elements;
                if (!mhi_chan->tre_ring.elements)
                        goto error_chan_cfg;

                /*
                 * For some channels, local ring length should be bigger than
                 * the transfer ring length due to internal logical channels
                 * in device. So host can queue much more buffers than transfer
                 * ring length. Example, RSC channels should have a larger local
                 * channel length than transfer ring length.
                 */
                mhi_chan->buf_ring.elements = ch_cfg->local_elements;
                if (!mhi_chan->buf_ring.elements)
                        mhi_chan->buf_ring.elements = mhi_chan->tre_ring.elements;
                mhi_chan->er_index = ch_cfg->event_ring;
                mhi_chan->dir = ch_cfg->dir;

                /*
                 * For most channels, chtype is identical to channel directions.
                 * So, if it is not defined then assign channel direction to
                 * chtype
                 */
                mhi_chan->type = ch_cfg->type;
                if (!mhi_chan->type)
                        mhi_chan->type = (enum mhi_ch_type)mhi_chan->dir;

                mhi_chan->ee_mask = ch_cfg->ee_mask;
                mhi_chan->db_cfg.pollcfg = ch_cfg->pollcfg;
                mhi_chan->lpm_notify = ch_cfg->lpm_notify;
                mhi_chan->offload_ch = ch_cfg->offload_channel;
                mhi_chan->db_cfg.reset_req = ch_cfg->doorbell_mode_switch;
                mhi_chan->wake_capable = ch_cfg->wake_capable;

                /*
                 * Bi-directional and direction less channel must be an
                 * offload channel
                 */
                if ((mhi_chan->dir == DMA_BIDIRECTIONAL ||
                     mhi_chan->dir == DMA_NONE) && !mhi_chan->offload_ch) {
                        dev_err(dev, "Invalid channel configuration\n");
                        goto error_chan_cfg;
                }

                if (!mhi_chan->offload_ch) {
                        mhi_chan->db_cfg.brstmode = ch_cfg->doorbell;
                        if (MHI_INVALID_BRSTMODE(mhi_chan->db_cfg.brstmode)) {
                                dev_err(dev, "Invalid Door bell mode\n");
                                goto error_chan_cfg;
                        }
                }

                if (mhi_chan->db_cfg.brstmode == MHI_DB_BRST_ENABLE)
                        mhi_chan->db_cfg.process_db = mhi_db_brstmode;
                else
                        mhi_chan->db_cfg.process_db = mhi_db_brstmode_disable;

                mhi_chan->configured = true;

                if (mhi_chan->lpm_notify)
                        list_add_tail(&mhi_chan->node, &mhi_cntrl->lpm_chans);
        }

        return 0;

error_chan_cfg:
        vfree(mhi_cntrl->mhi_chan);

        return -EINVAL;
}

static int parse_config(struct mhi_controller *mhi_cntrl,
                        const struct mhi_controller_config *config)
{
        int ret;

        /* Parse MHI channel configuration */
        ret = parse_ch_cfg(mhi_cntrl, config);
        if (ret)
                return ret;

        /* Parse MHI event configuration */
        ret = parse_ev_cfg(mhi_cntrl, config);
        if (ret)
                goto error_ev_cfg;

        mhi_cntrl->timeout_ms = config->timeout_ms;
        if (!mhi_cntrl->timeout_ms)
                mhi_cntrl->timeout_ms = MHI_TIMEOUT_MS;

        mhi_cntrl->ready_timeout_ms = config->ready_timeout_ms;
        mhi_cntrl->bounce_buf = config->use_bounce_buf;
        mhi_cntrl->buffer_len = config->buf_len;
        if (!mhi_cntrl->buffer_len)
                mhi_cntrl->buffer_len = MHI_MAX_MTU;

        /* By default, host is allowed to ring DB in both M0 and M2 states */
        mhi_cntrl->db_access = MHI_PM_M0 | MHI_PM_M2;
        if (config->m2_no_db)
                mhi_cntrl->db_access &= ~MHI_PM_M2;

        return 0;

error_ev_cfg:
        vfree(mhi_cntrl->mhi_chan);

        return ret;
}

int mhi_register_controller(struct mhi_controller *mhi_cntrl,
                            const struct mhi_controller_config *config)
{
        struct mhi_event *mhi_event;
        struct mhi_chan *mhi_chan;
        struct mhi_cmd *mhi_cmd;
        struct mhi_device *mhi_dev;
        int ret, i;

        if (!mhi_cntrl || !mhi_cntrl->cntrl_dev || !mhi_cntrl->regs ||
            !mhi_cntrl->runtime_get || !mhi_cntrl->runtime_put ||
            !mhi_cntrl->status_cb || !mhi_cntrl->read_reg ||
            !mhi_cntrl->write_reg || !mhi_cntrl->nr_irqs ||
            !mhi_cntrl->irq || !mhi_cntrl->reg_len)
                return -EINVAL;

        ret = parse_config(mhi_cntrl, config);
        if (ret)
                return -EINVAL;

        mhi_cntrl->mhi_cmd = kzalloc_objs(*mhi_cntrl->mhi_cmd, NR_OF_CMD_RINGS);
        if (!mhi_cntrl->mhi_cmd) {
                ret = -ENOMEM;
                goto err_free_event;
        }

        INIT_LIST_HEAD(&mhi_cntrl->transition_list);
        mutex_init(&mhi_cntrl->pm_mutex);
        rwlock_init(&mhi_cntrl->pm_lock);
        spin_lock_init(&mhi_cntrl->transition_lock);
        spin_lock_init(&mhi_cntrl->wlock);
        INIT_WORK(&mhi_cntrl->st_worker, mhi_pm_st_worker);
        init_waitqueue_head(&mhi_cntrl->state_event);

        mhi_cntrl->hiprio_wq = alloc_ordered_workqueue("mhi_hiprio_wq", WQ_HIGHPRI);
        if (!mhi_cntrl->hiprio_wq) {
                dev_err(mhi_cntrl->cntrl_dev, "Failed to allocate workqueue\n");
                ret = -ENOMEM;
                goto err_free_cmd;
        }

        mhi_cmd = mhi_cntrl->mhi_cmd;
        for (i = 0; i < NR_OF_CMD_RINGS; i++, mhi_cmd++)
                spin_lock_init(&mhi_cmd->lock);

        mhi_event = mhi_cntrl->mhi_event;
        for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
                /* Skip for offload events */
                if (mhi_event->offload_ev)
                        continue;

                mhi_event->mhi_cntrl = mhi_cntrl;
                spin_lock_init(&mhi_event->lock);
                if (mhi_event->data_type == MHI_ER_CTRL)
                        tasklet_init(&mhi_event->task, mhi_ctrl_ev_task,
                                     (ulong)mhi_event);
                else
                        tasklet_init(&mhi_event->task, mhi_ev_task,
                                     (ulong)mhi_event);
        }

        mhi_chan = mhi_cntrl->mhi_chan;
        for (i = 0; i < mhi_cntrl->max_chan; i++, mhi_chan++) {
                mutex_init(&mhi_chan->mutex);
                init_completion(&mhi_chan->completion);
                rwlock_init(&mhi_chan->lock);

                /* used in setting bei field of TRE */
                mhi_event = &mhi_cntrl->mhi_event[mhi_chan->er_index];
                mhi_chan->intmod = mhi_event->intmod;
        }

        if (mhi_cntrl->bounce_buf) {
                mhi_cntrl->map_single = mhi_map_single_use_bb;
                mhi_cntrl->unmap_single = mhi_unmap_single_use_bb;
        } else {
                mhi_cntrl->map_single = mhi_map_single_no_bb;
                mhi_cntrl->unmap_single = mhi_unmap_single_no_bb;
        }

        mhi_cntrl->index = ida_alloc(&mhi_controller_ida, GFP_KERNEL);
        if (mhi_cntrl->index < 0) {
                ret = mhi_cntrl->index;
                goto err_destroy_wq;
        }

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

        /* Register controller with MHI bus */
        mhi_dev = mhi_alloc_device(mhi_cntrl);
        if (IS_ERR(mhi_dev)) {
                dev_err(mhi_cntrl->cntrl_dev, "Failed to allocate MHI device\n");
                ret = PTR_ERR(mhi_dev);
                goto error_setup_irq;
        }

        mhi_dev->dev_type = MHI_DEVICE_CONTROLLER;
        mhi_dev->mhi_cntrl = mhi_cntrl;
        dev_set_name(&mhi_dev->dev, "mhi%d", mhi_cntrl->index);
        mhi_dev->name = dev_name(&mhi_dev->dev);

        /* Init wakeup source */
        device_init_wakeup(&mhi_dev->dev, true);

        ret = device_add(&mhi_dev->dev);
        if (ret)
                goto err_release_dev;

        if (mhi_cntrl->edl_trigger) {
                ret = sysfs_create_file(&mhi_dev->dev.kobj, &dev_attr_trigger_edl.attr);
                if (ret)
                        goto err_release_dev;
        }

        mhi_cntrl->mhi_dev = mhi_dev;

        mhi_create_debugfs(mhi_cntrl);

        return 0;

err_release_dev:
        put_device(&mhi_dev->dev);
error_setup_irq:
        mhi_deinit_free_irq(mhi_cntrl);
err_ida_free:
        ida_free(&mhi_controller_ida, mhi_cntrl->index);
err_destroy_wq:
        destroy_workqueue(mhi_cntrl->hiprio_wq);
err_free_cmd:
        kfree(mhi_cntrl->mhi_cmd);
err_free_event:
        kfree(mhi_cntrl->mhi_event);
        vfree(mhi_cntrl->mhi_chan);

        return ret;
}
EXPORT_SYMBOL_GPL(mhi_register_controller);

void mhi_unregister_controller(struct mhi_controller *mhi_cntrl)
{
        struct mhi_device *mhi_dev = mhi_cntrl->mhi_dev;
        struct mhi_chan *mhi_chan = mhi_cntrl->mhi_chan;
        unsigned int i;

        mhi_deinit_free_irq(mhi_cntrl);
        mhi_destroy_debugfs(mhi_cntrl);

        if (mhi_cntrl->edl_trigger)
                sysfs_remove_file(&mhi_dev->dev.kobj, &dev_attr_trigger_edl.attr);

        destroy_workqueue(mhi_cntrl->hiprio_wq);
        kfree(mhi_cntrl->mhi_cmd);
        kfree(mhi_cntrl->mhi_event);

        /* Drop the references to MHI devices created for channels */
        for (i = 0; i < mhi_cntrl->max_chan; i++, mhi_chan++) {
                if (!mhi_chan->mhi_dev)
                        continue;

                put_device(&mhi_chan->mhi_dev->dev);
        }
        vfree(mhi_cntrl->mhi_chan);

        device_del(&mhi_dev->dev);
        put_device(&mhi_dev->dev);

        ida_free(&mhi_controller_ida, mhi_cntrl->index);
}
EXPORT_SYMBOL_GPL(mhi_unregister_controller);

struct mhi_controller *mhi_alloc_controller(void)
{
        struct mhi_controller *mhi_cntrl;

        mhi_cntrl = kzalloc_obj(*mhi_cntrl);

        return mhi_cntrl;
}
EXPORT_SYMBOL_GPL(mhi_alloc_controller);

void mhi_free_controller(struct mhi_controller *mhi_cntrl)
{
        kfree(mhi_cntrl);
}
EXPORT_SYMBOL_GPL(mhi_free_controller);

int mhi_prepare_for_power_up(struct mhi_controller *mhi_cntrl)
{
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        u32 bhi_off, bhie_off;
        int ret;

        mutex_lock(&mhi_cntrl->pm_mutex);

        ret = mhi_init_dev_ctxt(mhi_cntrl);
        if (ret)
                goto error_dev_ctxt;

        ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->regs, BHIOFF, &bhi_off);
        if (ret) {
                dev_err(dev, "Error getting BHI offset\n");
                goto error_reg_offset;
        }

        if (bhi_off >= mhi_cntrl->reg_len) {
                dev_err(dev, "BHI offset: 0x%x is out of range: 0x%zx\n",
                        bhi_off, mhi_cntrl->reg_len);
                ret = -ERANGE;
                goto error_reg_offset;
        }
        mhi_cntrl->bhi = mhi_cntrl->regs + bhi_off;

        if (mhi_cntrl->fbc_download || mhi_cntrl->rddm_size || mhi_cntrl->seg_len) {
                ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->regs, BHIEOFF,
                                   &bhie_off);
                if (ret) {
                        dev_err(dev, "Error getting BHIE offset\n");
                        goto error_reg_offset;
                }

                if (bhie_off >= mhi_cntrl->reg_len) {
                        dev_err(dev,
                                "BHIe offset: 0x%x is out of range: 0x%zx\n",
                                bhie_off, mhi_cntrl->reg_len);
                        ret = -ERANGE;
                        goto error_reg_offset;
                }
                mhi_cntrl->bhie = mhi_cntrl->regs + bhie_off;
        }

        if (mhi_cntrl->rddm_size) {
                /*
                 * This controller supports RDDM, so we need to manually clear
                 * BHIE RX registers since POR values are undefined.
                 */
                memset_io(mhi_cntrl->bhie + BHIE_RXVECADDR_LOW_OFFS,
                          0, BHIE_RXVECSTATUS_OFFS - BHIE_RXVECADDR_LOW_OFFS +
                          4);
                /*
                 * Allocate RDDM table for debugging purpose if specified
                 */
                mhi_alloc_bhie_table(mhi_cntrl, &mhi_cntrl->rddm_image,
                                     mhi_cntrl->rddm_size);
                if (mhi_cntrl->rddm_image) {
                        ret = mhi_rddm_prepare(mhi_cntrl,
                                               mhi_cntrl->rddm_image);
                        if (ret) {
                                mhi_free_bhie_table(mhi_cntrl,
                                                    mhi_cntrl->rddm_image);
                                goto error_reg_offset;
                        }
                }
        }

        mutex_unlock(&mhi_cntrl->pm_mutex);

        return 0;

error_reg_offset:
        mhi_deinit_dev_ctxt(mhi_cntrl);

error_dev_ctxt:
        mutex_unlock(&mhi_cntrl->pm_mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(mhi_prepare_for_power_up);

void mhi_unprepare_after_power_down(struct mhi_controller *mhi_cntrl)
{
        if (mhi_cntrl->fbc_image) {
                mhi_free_bhie_table(mhi_cntrl, mhi_cntrl->fbc_image);
                mhi_cntrl->fbc_image = NULL;
        }

        if (mhi_cntrl->rddm_image) {
                mhi_free_bhie_table(mhi_cntrl, mhi_cntrl->rddm_image);
                mhi_cntrl->rddm_image = NULL;
        }

        mhi_cntrl->bhi = NULL;
        mhi_cntrl->bhie = NULL;

        mhi_deinit_dev_ctxt(mhi_cntrl);
}
EXPORT_SYMBOL_GPL(mhi_unprepare_after_power_down);

static void mhi_release_device(struct device *dev)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);

        /*
         * We need to set the mhi_chan->mhi_dev to NULL here since the MHI
         * devices for the channels will only get created if the mhi_dev
         * associated with it is NULL. This scenario will happen during the
         * controller suspend and resume.
         */
        if (mhi_dev->ul_chan)
                mhi_dev->ul_chan->mhi_dev = NULL;

        if (mhi_dev->dl_chan)
                mhi_dev->dl_chan->mhi_dev = NULL;

        kfree(mhi_dev);
}

struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl)
{
        struct mhi_device *mhi_dev;
        struct device *dev;

        mhi_dev = kzalloc_obj(*mhi_dev);
        if (!mhi_dev)
                return ERR_PTR(-ENOMEM);

        dev = &mhi_dev->dev;
        device_initialize(dev);
        dev->bus = &mhi_bus_type;
        dev->release = mhi_release_device;

        if (mhi_cntrl->mhi_dev) {
                /* for MHI client devices, parent is the MHI controller device */
                dev->parent = &mhi_cntrl->mhi_dev->dev;
        } else {
                /* for MHI controller device, parent is the bus device (e.g. pci device) */
                dev->parent = mhi_cntrl->cntrl_dev;
        }

        mhi_dev->mhi_cntrl = mhi_cntrl;
        mhi_dev->dev_wake = 0;

        return mhi_dev;
}

static int mhi_probe(struct device *dev)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
        struct device_driver *drv = dev->driver;
        struct mhi_driver *mhi_drv = to_mhi_driver(drv);
        struct mhi_event *mhi_event;
        struct mhi_chan *ul_chan = mhi_dev->ul_chan;
        struct mhi_chan *dl_chan = mhi_dev->dl_chan;
        int ret;

        /* Bring device out of LPM */
        ret = mhi_device_get_sync(mhi_dev);
        if (ret)
                return ret;

        ret = -EINVAL;

        if (ul_chan) {
                /*
                 * If channel supports LPM notifications then status_cb should
                 * be provided
                 */
                if (ul_chan->lpm_notify && !mhi_drv->status_cb)
                        goto exit_probe;

                /* For non-offload channels then xfer_cb should be provided */
                if (!ul_chan->offload_ch && !mhi_drv->ul_xfer_cb)
                        goto exit_probe;

                ul_chan->xfer_cb = mhi_drv->ul_xfer_cb;
        }

        ret = -EINVAL;
        if (dl_chan) {
                /*
                 * If channel supports LPM notifications then status_cb should
                 * be provided
                 */
                if (dl_chan->lpm_notify && !mhi_drv->status_cb)
                        goto exit_probe;

                /* For non-offload channels then xfer_cb should be provided */
                if (!dl_chan->offload_ch && !mhi_drv->dl_xfer_cb)
                        goto exit_probe;

                mhi_event = &mhi_cntrl->mhi_event[dl_chan->er_index];

                /*
                 * If the channel event ring is managed by client, then
                 * status_cb must be provided so that the framework can
                 * notify pending data
                 */
                if (mhi_event->cl_manage && !mhi_drv->status_cb)
                        goto exit_probe;

                dl_chan->xfer_cb = mhi_drv->dl_xfer_cb;
        }

        /* Call the user provided probe function */
        ret = mhi_drv->probe(mhi_dev, mhi_dev->id);
        if (ret)
                goto exit_probe;

        mhi_device_put(mhi_dev);

        return ret;

exit_probe:
        mhi_unprepare_from_transfer(mhi_dev);

        mhi_device_put(mhi_dev);

        return ret;
}

static void mhi_remove(struct device *dev)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);
        struct mhi_driver *mhi_drv = to_mhi_driver(dev->driver);
        struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
        struct mhi_chan *mhi_chan;
        enum mhi_ch_state ch_state[] = {
                MHI_CH_STATE_DISABLED,
                MHI_CH_STATE_DISABLED
        };
        int dir;

        /* Skip if it is a controller device */
        if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
                return;

        /* Reset both channels */
        for (dir = 0; dir < 2; dir++) {
                mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;

                if (!mhi_chan)
                        continue;

                /* Wake all threads waiting for completion */
                write_lock_irq(&mhi_chan->lock);
                mhi_chan->ccs = MHI_EV_CC_INVALID;
                complete_all(&mhi_chan->completion);
                write_unlock_irq(&mhi_chan->lock);

                /* Set the channel state to disabled */
                mutex_lock(&mhi_chan->mutex);
                write_lock_irq(&mhi_chan->lock);
                ch_state[dir] = mhi_chan->ch_state;
                mhi_chan->ch_state = MHI_CH_STATE_SUSPENDED;
                write_unlock_irq(&mhi_chan->lock);

                /* Reset the non-offload channel */
                if (!mhi_chan->offload_ch)
                        mhi_reset_chan(mhi_cntrl, mhi_chan);

                mutex_unlock(&mhi_chan->mutex);
        }

        mhi_drv->remove(mhi_dev);

        /* De-init channel if it was enabled */
        for (dir = 0; dir < 2; dir++) {
                mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;

                if (!mhi_chan)
                        continue;

                mutex_lock(&mhi_chan->mutex);

                if ((ch_state[dir] == MHI_CH_STATE_ENABLED ||
                     ch_state[dir] == MHI_CH_STATE_STOP) &&
                    !mhi_chan->offload_ch)
                        mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);

                mhi_chan->ch_state = MHI_CH_STATE_DISABLED;

                mutex_unlock(&mhi_chan->mutex);
        }

        while (mhi_dev->dev_wake)
                mhi_device_put(mhi_dev);
}

int __mhi_driver_register(struct mhi_driver *mhi_drv, struct module *owner)
{
        struct device_driver *driver = &mhi_drv->driver;

        if (!mhi_drv->probe || !mhi_drv->remove)
                return -EINVAL;

        driver->bus = &mhi_bus_type;
        driver->owner = owner;

        return driver_register(driver);
}
EXPORT_SYMBOL_GPL(__mhi_driver_register);

void mhi_driver_unregister(struct mhi_driver *mhi_drv)
{
        driver_unregister(&mhi_drv->driver);
}
EXPORT_SYMBOL_GPL(mhi_driver_unregister);

static int mhi_uevent(const struct device *dev, struct kobj_uevent_env *env)
{
        const struct mhi_device *mhi_dev = to_mhi_device(dev);

        return add_uevent_var(env, "MODALIAS=" MHI_DEVICE_MODALIAS_FMT,
                                        mhi_dev->name);
}

static int mhi_match(struct device *dev, const struct device_driver *drv)
{
        struct mhi_device *mhi_dev = to_mhi_device(dev);
        const struct mhi_driver *mhi_drv = to_mhi_driver(drv);
        const struct mhi_device_id *id;

        /*
         * If the device is a controller type then there is no client driver
         * associated with it
         */
        if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
                return 0;

        for (id = mhi_drv->id_table; id->chan[0]; id++)
                if (!strcmp(mhi_dev->name, id->chan)) {
                        mhi_dev->id = id;
                        return 1;
                }

        return 0;
};

const struct bus_type mhi_bus_type = {
        .name = "mhi",
        .dev_name = "mhi",
        .match = mhi_match,
        .uevent = mhi_uevent,
        .probe = mhi_probe,
        .remove = mhi_remove,
        .dev_groups = mhi_dev_groups,
};

static int __init mhi_init(void)
{
        mhi_debugfs_init();
        return bus_register(&mhi_bus_type);
}

static void __exit mhi_exit(void)
{
        mhi_debugfs_exit();
        bus_unregister(&mhi_bus_type);
}

postcore_initcall(mhi_init);
module_exit(mhi_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Modem Host Interface");