// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2022 Linaro Ltd.
 * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
 */

#include <linux/mhi_ep.h>
#include "internal.h"

size_t mhi_ep_ring_addr2offset(struct mhi_ep_ring *ring, u64 ptr)
{
        return (ptr - ring->rbase) / sizeof(struct mhi_ring_element);
}

static u32 mhi_ep_ring_num_elems(struct mhi_ep_ring *ring)
{
        __le64 rlen;

        memcpy_fromio(&rlen, (void __iomem *) &ring->ring_ctx->generic.rlen, sizeof(u64));

        return le64_to_cpu(rlen) / sizeof(struct mhi_ring_element);
}

void mhi_ep_ring_inc_index(struct mhi_ep_ring *ring)
{
        ring->rd_offset = (ring->rd_offset + 1) % ring->ring_size;
}

static int __mhi_ep_cache_ring(struct mhi_ep_ring *ring, size_t end)
{
        struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        struct mhi_ep_buf_info buf_info = {};
        size_t start;
        int ret;

        /* Don't proceed in the case of event ring. This happens during mhi_ep_ring_start(). */
        if (ring->type == RING_TYPE_ER)
                return 0;

        /* No need to cache the ring if write pointer is unmodified */
        if (ring->wr_offset == end)
                return 0;

        start = ring->wr_offset;
        if (start < end) {
                buf_info.size = (end - start) * sizeof(struct mhi_ring_element);
                buf_info.host_addr = ring->rbase + (start * sizeof(struct mhi_ring_element));
                buf_info.dev_addr = &ring->ring_cache[start];

                ret = mhi_cntrl->read_sync(mhi_cntrl, &buf_info);
                if (ret < 0)
                        return ret;
        } else {
                buf_info.size = (ring->ring_size - start) * sizeof(struct mhi_ring_element);
                buf_info.host_addr = ring->rbase + (start * sizeof(struct mhi_ring_element));
                buf_info.dev_addr = &ring->ring_cache[start];

                ret = mhi_cntrl->read_sync(mhi_cntrl, &buf_info);
                if (ret < 0)
                        return ret;

                if (end) {
                        buf_info.host_addr = ring->rbase;
                        buf_info.dev_addr = &ring->ring_cache[0];
                        buf_info.size = end * sizeof(struct mhi_ring_element);

                        ret = mhi_cntrl->read_sync(mhi_cntrl, &buf_info);
                        if (ret < 0)
                                return ret;
                }
        }

        dev_dbg(dev, "Cached ring: start %zu end %zu size %zu\n", start, end, buf_info.size);

        return 0;
}

static int mhi_ep_cache_ring(struct mhi_ep_ring *ring, u64 wr_ptr)
{
        size_t wr_offset;
        int ret;

        wr_offset = mhi_ep_ring_addr2offset(ring, wr_ptr);

        /* Cache the host ring till write offset */
        ret = __mhi_ep_cache_ring(ring, wr_offset);
        if (ret)
                return ret;

        ring->wr_offset = wr_offset;

        return 0;
}

int mhi_ep_update_wr_offset(struct mhi_ep_ring *ring)
{
        u64 wr_ptr;

        wr_ptr = mhi_ep_mmio_get_db(ring);

        return mhi_ep_cache_ring(ring, wr_ptr);
}

/* TODO: Support for adding multiple ring elements to the ring */
int mhi_ep_ring_add_element(struct mhi_ep_ring *ring, struct mhi_ring_element *el)
{
        struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        struct mhi_ep_buf_info buf_info = {};
        size_t old_offset = 0;
        u32 num_free_elem;
        __le64 rp;
        int ret;

        ret = mhi_ep_update_wr_offset(ring);
        if (ret) {
                dev_err(dev, "Error updating write pointer\n");
                return ret;
        }

        if (ring->rd_offset < ring->wr_offset)
                num_free_elem = (ring->wr_offset - ring->rd_offset) - 1;
        else
                num_free_elem = ((ring->ring_size - ring->rd_offset) + ring->wr_offset) - 1;

        /* Check if there is space in ring for adding at least an element */
        if (!num_free_elem) {
                dev_err(dev, "No space left in the ring\n");
                return -ENOSPC;
        }

        old_offset = ring->rd_offset;

        dev_dbg(dev, "Adding an element to ring at offset (%zu)\n", ring->rd_offset);
        buf_info.host_addr = ring->rbase + (old_offset * sizeof(*el));
        buf_info.dev_addr = el;
        buf_info.size = sizeof(*el);

        ret = mhi_cntrl->write_sync(mhi_cntrl, &buf_info);
        if (ret)
                return ret;

        mhi_ep_ring_inc_index(ring);

        /* Update rp in ring context */
        rp = cpu_to_le64(ring->rd_offset * sizeof(*el) + ring->rbase);
        memcpy_toio((void __iomem *) &ring->ring_ctx->generic.rp, &rp, sizeof(u64));

        return ret;
}

void mhi_ep_ring_init(struct mhi_ep_ring *ring, enum mhi_ep_ring_type type, u32 id)
{
        ring->type = type;
        if (ring->type == RING_TYPE_CMD) {
                ring->db_offset_h = EP_CRDB_HIGHER;
                ring->db_offset_l = EP_CRDB_LOWER;
        } else if (ring->type == RING_TYPE_CH) {
                ring->db_offset_h = CHDB_HIGHER_n(id);
                ring->db_offset_l = CHDB_LOWER_n(id);
                ring->ch_id = id;
        } else {
                ring->db_offset_h = ERDB_HIGHER_n(id);
                ring->db_offset_l = ERDB_LOWER_n(id);
        }
}

static void mhi_ep_raise_irq(struct work_struct *work)
{
        struct mhi_ep_ring *ring = container_of(work, struct mhi_ep_ring, intmodt_work.work);
        struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;

        mhi_cntrl->raise_irq(mhi_cntrl, ring->irq_vector);
        WRITE_ONCE(ring->irq_pending, false);
}

int mhi_ep_ring_start(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring,
                        union mhi_ep_ring_ctx *ctx)
{
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        __le64 val;
        int ret;

        ring->mhi_cntrl = mhi_cntrl;
        ring->ring_ctx = ctx;
        ring->ring_size = mhi_ep_ring_num_elems(ring);
        memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.rbase, sizeof(u64));
        ring->rbase = le64_to_cpu(val);

        if (ring->type == RING_TYPE_CH)
                ring->er_index = le32_to_cpu(ring->ring_ctx->ch.erindex);

        if (ring->type == RING_TYPE_ER) {
                ring->irq_vector = le32_to_cpu(ring->ring_ctx->ev.msivec);
                ring->intmodt = FIELD_GET(EV_CTX_INTMODT_MASK,
                                          le32_to_cpu(ring->ring_ctx->ev.intmod));

                INIT_DELAYED_WORK(&ring->intmodt_work, mhi_ep_raise_irq);
        }

        /* During ring init, both rp and wp are equal */
        memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.rp, sizeof(u64));
        ring->rd_offset = mhi_ep_ring_addr2offset(ring, le64_to_cpu(val));
        ring->wr_offset = mhi_ep_ring_addr2offset(ring, le64_to_cpu(val));

        /* Allocate ring cache memory for holding the copy of host ring */
        ring->ring_cache = kzalloc_objs(struct mhi_ring_element,
                                        ring->ring_size);
        if (!ring->ring_cache)
                return -ENOMEM;

        memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.wp, sizeof(u64));
        ret = mhi_ep_cache_ring(ring, le64_to_cpu(val));
        if (ret) {
                dev_err(dev, "Failed to cache ring\n");
                kfree(ring->ring_cache);
                return ret;
        }

        ring->started = true;

        return 0;
}

void mhi_ep_ring_reset(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring)
{
        if (ring->type == RING_TYPE_ER)
                cancel_delayed_work_sync(&ring->intmodt_work);

        ring->started = false;
        kfree(ring->ring_cache);
        ring->ring_cache = NULL;
}