// SPDX-License-Identifier: GPL-2.0-only
/*
 * AMD Cryptographic Coprocessor (CCP) driver
 *
 * Copyright (C) 2016,2019 Advanced Micro Devices, Inc.
 *
 * Author: Gary R Hook <gary.hook@amd.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/ccp.h>

#include "ccp-dev.h"
#include "../../dma/dmaengine.h"

#define CCP_DMA_WIDTH(_mask)            \
({                                      \
        u64 mask = _mask + 1;           \
        (mask == 0) ? 64 : fls64(mask); \
})

/* The CCP as a DMA provider can be configured for public or private
 * channels. Default is specified in the vdata for the device (PCI ID).
 * This module parameter will override for all channels on all devices:
 *   dma_chan_attr = 0x2 to force all channels public
 *                 = 0x1 to force all channels private
 *                 = 0x0 to defer to the vdata setting
 *                 = any other value: warning, revert to 0x0
 */
static unsigned int dma_chan_attr = CCP_DMA_DFLT;
module_param(dma_chan_attr, uint, 0444);
MODULE_PARM_DESC(dma_chan_attr, "Set DMA channel visibility: 0 (default) = device defaults, 1 = make private, 2 = make public");

static unsigned int dmaengine = 1;
module_param(dmaengine, uint, 0444);
MODULE_PARM_DESC(dmaengine, "Register services with the DMA subsystem (any non-zero value, default: 1)");

static unsigned int ccp_get_dma_chan_attr(struct ccp_device *ccp)
{
        switch (dma_chan_attr) {
        case CCP_DMA_DFLT:
                return ccp->vdata->dma_chan_attr;

        case CCP_DMA_PRIV:
                return DMA_PRIVATE;

        case CCP_DMA_PUB:
                return 0;

        default:
                dev_info_once(ccp->dev, "Invalid value for dma_chan_attr: %d\n",
                              dma_chan_attr);
                return ccp->vdata->dma_chan_attr;
        }
}

static void ccp_free_cmd_resources(struct ccp_device *ccp,
                                   struct list_head *list)
{
        struct ccp_dma_cmd *cmd, *ctmp;

        list_for_each_entry_safe(cmd, ctmp, list, entry) {
                list_del(&cmd->entry);
                kmem_cache_free(ccp->dma_cmd_cache, cmd);
        }
}

static void ccp_free_desc_resources(struct ccp_device *ccp,
                                    struct list_head *list)
{
        struct ccp_dma_desc *desc, *dtmp;

        list_for_each_entry_safe(desc, dtmp, list, entry) {
                ccp_free_cmd_resources(ccp, &desc->active);
                ccp_free_cmd_resources(ccp, &desc->pending);

                list_del(&desc->entry);
                kmem_cache_free(ccp->dma_desc_cache, desc);
        }
}

static void ccp_free_chan_resources(struct dma_chan *dma_chan)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        unsigned long flags;

        dev_dbg(chan->ccp->dev, "%s - chan=%p\n", __func__, chan);

        spin_lock_irqsave(&chan->lock, flags);

        ccp_free_desc_resources(chan->ccp, &chan->complete);
        ccp_free_desc_resources(chan->ccp, &chan->active);
        ccp_free_desc_resources(chan->ccp, &chan->pending);
        ccp_free_desc_resources(chan->ccp, &chan->created);

        spin_unlock_irqrestore(&chan->lock, flags);
}

static void ccp_cleanup_desc_resources(struct ccp_device *ccp,
                                       struct list_head *list)
{
        struct ccp_dma_desc *desc, *dtmp;

        list_for_each_entry_safe_reverse(desc, dtmp, list, entry) {
                if (!async_tx_test_ack(&desc->tx_desc))
                        continue;

                dev_dbg(ccp->dev, "%s - desc=%p\n", __func__, desc);

                ccp_free_cmd_resources(ccp, &desc->active);
                ccp_free_cmd_resources(ccp, &desc->pending);

                list_del(&desc->entry);
                kmem_cache_free(ccp->dma_desc_cache, desc);
        }
}

static void ccp_do_cleanup(unsigned long data)
{
        struct ccp_dma_chan *chan = (struct ccp_dma_chan *)data;
        unsigned long flags;

        dev_dbg(chan->ccp->dev, "%s - chan=%s\n", __func__,
                dma_chan_name(&chan->dma_chan));

        spin_lock_irqsave(&chan->lock, flags);

        ccp_cleanup_desc_resources(chan->ccp, &chan->complete);

        spin_unlock_irqrestore(&chan->lock, flags);
}

static int ccp_issue_next_cmd(struct ccp_dma_desc *desc)
{
        struct ccp_dma_cmd *cmd;
        int ret;

        cmd = list_first_entry(&desc->pending, struct ccp_dma_cmd, entry);
        list_move(&cmd->entry, &desc->active);

        dev_dbg(desc->ccp->dev, "%s - tx %d, cmd=%p\n", __func__,
                desc->tx_desc.cookie, cmd);

        ret = ccp_enqueue_cmd(&cmd->ccp_cmd);
        if (!ret || (ret == -EINPROGRESS) || (ret == -EBUSY))
                return 0;

        dev_dbg(desc->ccp->dev, "%s - error: ret=%d, tx %d, cmd=%p\n", __func__,
                ret, desc->tx_desc.cookie, cmd);

        return ret;
}

static void ccp_free_active_cmd(struct ccp_dma_desc *desc)
{
        struct ccp_dma_cmd *cmd;

        cmd = list_first_entry_or_null(&desc->active, struct ccp_dma_cmd,
                                       entry);
        if (!cmd)
                return;

        dev_dbg(desc->ccp->dev, "%s - freeing tx %d cmd=%p\n",
                __func__, desc->tx_desc.cookie, cmd);

        list_del(&cmd->entry);
        kmem_cache_free(desc->ccp->dma_cmd_cache, cmd);
}

static struct ccp_dma_desc *__ccp_next_dma_desc(struct ccp_dma_chan *chan,
                                                struct ccp_dma_desc *desc)
{
        /* Move current DMA descriptor to the complete list */
        if (desc)
                list_move(&desc->entry, &chan->complete);

        /* Get the next DMA descriptor on the active list */
        desc = list_first_entry_or_null(&chan->active, struct ccp_dma_desc,
                                        entry);

        return desc;
}

static struct ccp_dma_desc *ccp_handle_active_desc(struct ccp_dma_chan *chan,
                                                   struct ccp_dma_desc *desc)
{
        struct dma_async_tx_descriptor *tx_desc;
        unsigned long flags;

        /* Loop over descriptors until one is found with commands */
        do {
                if (desc) {
                        /* Remove the DMA command from the list and free it */
                        ccp_free_active_cmd(desc);

                        if (!list_empty(&desc->pending)) {
                                /* No errors, keep going */
                                if (desc->status != DMA_ERROR)
                                        return desc;

                                /* Error, free remaining commands and move on */
                                ccp_free_cmd_resources(desc->ccp,
                                                       &desc->pending);
                        }

                        tx_desc = &desc->tx_desc;
                } else {
                        tx_desc = NULL;
                }

                spin_lock_irqsave(&chan->lock, flags);

                if (desc) {
                        if (desc->status != DMA_ERROR)
                                desc->status = DMA_COMPLETE;

                        dev_dbg(desc->ccp->dev,
                                "%s - tx %d complete, status=%u\n", __func__,
                                desc->tx_desc.cookie, desc->status);

                        dma_cookie_complete(tx_desc);
                        dma_descriptor_unmap(tx_desc);
                }

                desc = __ccp_next_dma_desc(chan, desc);

                spin_unlock_irqrestore(&chan->lock, flags);

                if (tx_desc) {
                        dmaengine_desc_get_callback_invoke(tx_desc, NULL);

                        dma_run_dependencies(tx_desc);
                }
        } while (desc);

        return NULL;
}

static struct ccp_dma_desc *__ccp_pending_to_active(struct ccp_dma_chan *chan)
{
        struct ccp_dma_desc *desc;

        if (list_empty(&chan->pending))
                return NULL;

        desc = list_empty(&chan->active)
                ? list_first_entry(&chan->pending, struct ccp_dma_desc, entry)
                : NULL;

        list_splice_tail_init(&chan->pending, &chan->active);

        return desc;
}

static void ccp_cmd_callback(void *data, int err)
{
        struct ccp_dma_desc *desc = data;
        struct ccp_dma_chan *chan;
        int ret;

        if (err == -EINPROGRESS)
                return;

        chan = container_of(desc->tx_desc.chan, struct ccp_dma_chan,
                            dma_chan);

        dev_dbg(chan->ccp->dev, "%s - tx %d callback, err=%d\n",
                __func__, desc->tx_desc.cookie, err);

        if (err)
                desc->status = DMA_ERROR;

        while (true) {
                /* Check for DMA descriptor completion */
                desc = ccp_handle_active_desc(chan, desc);

                /* Don't submit cmd if no descriptor or DMA is paused */
                if (!desc || (chan->status == DMA_PAUSED))
                        break;

                ret = ccp_issue_next_cmd(desc);
                if (!ret)
                        break;

                desc->status = DMA_ERROR;
        }

        tasklet_schedule(&chan->cleanup_tasklet);
}

static dma_cookie_t ccp_tx_submit(struct dma_async_tx_descriptor *tx_desc)
{
        struct ccp_dma_desc *desc = container_of(tx_desc, struct ccp_dma_desc,
                                                 tx_desc);
        struct ccp_dma_chan *chan;
        dma_cookie_t cookie;
        unsigned long flags;

        chan = container_of(tx_desc->chan, struct ccp_dma_chan, dma_chan);

        spin_lock_irqsave(&chan->lock, flags);

        cookie = dma_cookie_assign(tx_desc);
        list_move_tail(&desc->entry, &chan->pending);

        spin_unlock_irqrestore(&chan->lock, flags);

        dev_dbg(chan->ccp->dev, "%s - added tx descriptor %d to pending list\n",
                __func__, cookie);

        return cookie;
}

static struct ccp_dma_cmd *ccp_alloc_dma_cmd(struct ccp_dma_chan *chan)
{
        struct ccp_dma_cmd *cmd;

        cmd = kmem_cache_alloc(chan->ccp->dma_cmd_cache, GFP_NOWAIT);
        if (cmd)
                memset(cmd, 0, sizeof(*cmd));

        return cmd;
}

static struct ccp_dma_desc *ccp_alloc_dma_desc(struct ccp_dma_chan *chan,
                                               unsigned long flags)
{
        struct ccp_dma_desc *desc;

        desc = kmem_cache_zalloc(chan->ccp->dma_desc_cache, GFP_NOWAIT);
        if (!desc)
                return NULL;

        dma_async_tx_descriptor_init(&desc->tx_desc, &chan->dma_chan);
        desc->tx_desc.flags = flags;
        desc->tx_desc.tx_submit = ccp_tx_submit;
        desc->ccp = chan->ccp;
        INIT_LIST_HEAD(&desc->entry);
        INIT_LIST_HEAD(&desc->pending);
        INIT_LIST_HEAD(&desc->active);
        desc->status = DMA_IN_PROGRESS;

        return desc;
}

static struct ccp_dma_desc *ccp_create_desc(struct dma_chan *dma_chan,
                                            struct scatterlist *dst_sg,
                                            unsigned int dst_nents,
                                            struct scatterlist *src_sg,
                                            unsigned int src_nents,
                                            unsigned long flags)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        struct ccp_device *ccp = chan->ccp;
        struct ccp_dma_desc *desc;
        struct ccp_dma_cmd *cmd;
        struct ccp_cmd *ccp_cmd;
        struct ccp_passthru_nomap_engine *ccp_pt;
        unsigned int src_offset, src_len;
        unsigned int dst_offset, dst_len;
        unsigned int len;
        unsigned long sflags;
        size_t total_len;

        if (!dst_sg || !src_sg)
                return NULL;

        if (!dst_nents || !src_nents)
                return NULL;

        desc = ccp_alloc_dma_desc(chan, flags);
        if (!desc)
                return NULL;

        total_len = 0;

        src_len = sg_dma_len(src_sg);
        src_offset = 0;

        dst_len = sg_dma_len(dst_sg);
        dst_offset = 0;

        while (true) {
                if (!src_len) {
                        src_nents--;
                        if (!src_nents)
                                break;

                        src_sg = sg_next(src_sg);
                        if (!src_sg)
                                break;

                        src_len = sg_dma_len(src_sg);
                        src_offset = 0;
                        continue;
                }

                if (!dst_len) {
                        dst_nents--;
                        if (!dst_nents)
                                break;

                        dst_sg = sg_next(dst_sg);
                        if (!dst_sg)
                                break;

                        dst_len = sg_dma_len(dst_sg);
                        dst_offset = 0;
                        continue;
                }

                len = min(dst_len, src_len);

                cmd = ccp_alloc_dma_cmd(chan);
                if (!cmd)
                        goto err;

                ccp_cmd = &cmd->ccp_cmd;
                ccp_cmd->ccp = chan->ccp;
                ccp_pt = &ccp_cmd->u.passthru_nomap;
                ccp_cmd->flags = CCP_CMD_MAY_BACKLOG;
                ccp_cmd->flags |= CCP_CMD_PASSTHRU_NO_DMA_MAP;
                ccp_cmd->engine = CCP_ENGINE_PASSTHRU;
                ccp_pt->bit_mod = CCP_PASSTHRU_BITWISE_NOOP;
                ccp_pt->byte_swap = CCP_PASSTHRU_BYTESWAP_NOOP;
                ccp_pt->src_dma = sg_dma_address(src_sg) + src_offset;
                ccp_pt->dst_dma = sg_dma_address(dst_sg) + dst_offset;
                ccp_pt->src_len = len;
                ccp_pt->final = 1;
                ccp_cmd->callback = ccp_cmd_callback;
                ccp_cmd->data = desc;

                list_add_tail(&cmd->entry, &desc->pending);

                dev_dbg(ccp->dev,
                        "%s - cmd=%p, src=%pad, dst=%pad, len=%llu\n", __func__,
                        cmd, &ccp_pt->src_dma,
                        &ccp_pt->dst_dma, ccp_pt->src_len);

                total_len += len;

                src_len -= len;
                src_offset += len;

                dst_len -= len;
                dst_offset += len;
        }

        desc->len = total_len;

        if (list_empty(&desc->pending))
                goto err;

        dev_dbg(ccp->dev, "%s - desc=%p\n", __func__, desc);

        spin_lock_irqsave(&chan->lock, sflags);

        list_add_tail(&desc->entry, &chan->created);

        spin_unlock_irqrestore(&chan->lock, sflags);

        return desc;

err:
        ccp_free_cmd_resources(ccp, &desc->pending);
        kmem_cache_free(ccp->dma_desc_cache, desc);

        return NULL;
}

static struct dma_async_tx_descriptor *ccp_prep_dma_memcpy(
        struct dma_chan *dma_chan, dma_addr_t dst, dma_addr_t src, size_t len,
        unsigned long flags)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        struct ccp_dma_desc *desc;
        struct scatterlist dst_sg, src_sg;

        dev_dbg(chan->ccp->dev,
                "%s - src=%pad, dst=%pad, len=%zu, flags=%#lx\n",
                __func__, &src, &dst, len, flags);

        sg_init_table(&dst_sg, 1);
        sg_dma_address(&dst_sg) = dst;
        sg_dma_len(&dst_sg) = len;

        sg_init_table(&src_sg, 1);
        sg_dma_address(&src_sg) = src;
        sg_dma_len(&src_sg) = len;

        desc = ccp_create_desc(dma_chan, &dst_sg, 1, &src_sg, 1, flags);
        if (!desc)
                return NULL;

        return &desc->tx_desc;
}

static struct dma_async_tx_descriptor *ccp_prep_dma_interrupt(
        struct dma_chan *dma_chan, unsigned long flags)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        struct ccp_dma_desc *desc;

        desc = ccp_alloc_dma_desc(chan, flags);
        if (!desc)
                return NULL;

        return &desc->tx_desc;
}

static void ccp_issue_pending(struct dma_chan *dma_chan)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        struct ccp_dma_desc *desc;
        unsigned long flags;

        dev_dbg(chan->ccp->dev, "%s\n", __func__);

        spin_lock_irqsave(&chan->lock, flags);

        desc = __ccp_pending_to_active(chan);

        spin_unlock_irqrestore(&chan->lock, flags);

        /* If there was nothing active, start processing */
        if (desc)
                ccp_cmd_callback(desc, 0);
}

static enum dma_status ccp_tx_status(struct dma_chan *dma_chan,
                                     dma_cookie_t cookie,
                                     struct dma_tx_state *state)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        struct ccp_dma_desc *desc;
        enum dma_status ret;
        unsigned long flags;

        if (chan->status == DMA_PAUSED) {
                ret = DMA_PAUSED;
                goto out;
        }

        ret = dma_cookie_status(dma_chan, cookie, state);
        if (ret == DMA_COMPLETE) {
                spin_lock_irqsave(&chan->lock, flags);

                /* Get status from complete chain, if still there */
                list_for_each_entry(desc, &chan->complete, entry) {
                        if (desc->tx_desc.cookie != cookie)
                                continue;

                        ret = desc->status;
                        break;
                }

                spin_unlock_irqrestore(&chan->lock, flags);
        }

out:
        dev_dbg(chan->ccp->dev, "%s - %u\n", __func__, ret);

        return ret;
}

static int ccp_pause(struct dma_chan *dma_chan)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);

        chan->status = DMA_PAUSED;

        /*TODO: Wait for active DMA to complete before returning? */

        return 0;
}

static int ccp_resume(struct dma_chan *dma_chan)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        struct ccp_dma_desc *desc;
        unsigned long flags;

        spin_lock_irqsave(&chan->lock, flags);

        desc = list_first_entry_or_null(&chan->active, struct ccp_dma_desc,
                                        entry);

        spin_unlock_irqrestore(&chan->lock, flags);

        /* Indicate the channel is running again */
        chan->status = DMA_IN_PROGRESS;

        /* If there was something active, re-start */
        if (desc)
                ccp_cmd_callback(desc, 0);

        return 0;
}

static int ccp_terminate_all(struct dma_chan *dma_chan)
{
        struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
                                                 dma_chan);
        unsigned long flags;

        dev_dbg(chan->ccp->dev, "%s\n", __func__);

        /*TODO: Wait for active DMA to complete before continuing */

        spin_lock_irqsave(&chan->lock, flags);

        /*TODO: Purge the complete list? */
        ccp_free_desc_resources(chan->ccp, &chan->active);
        ccp_free_desc_resources(chan->ccp, &chan->pending);
        ccp_free_desc_resources(chan->ccp, &chan->created);

        spin_unlock_irqrestore(&chan->lock, flags);

        return 0;
}

int ccp_dmaengine_register(struct ccp_device *ccp)
{
        struct ccp_dma_chan *chan;
        struct dma_device *dma_dev = &ccp->dma_dev;
        struct dma_chan *dma_chan;
        char *dma_cmd_cache_name;
        char *dma_desc_cache_name;
        unsigned int i;
        int ret;

        if (!dmaengine)
                return 0;

        ccp->ccp_dma_chan = devm_kcalloc(ccp->dev, ccp->cmd_q_count,
                                         sizeof(*(ccp->ccp_dma_chan)),
                                         GFP_KERNEL);
        if (!ccp->ccp_dma_chan)
                return -ENOMEM;

        dma_cmd_cache_name = devm_kasprintf(ccp->dev, GFP_KERNEL,
                                            "%s-dmaengine-cmd-cache",
                                            ccp->name);
        if (!dma_cmd_cache_name)
                return -ENOMEM;

        ccp->dma_cmd_cache = kmem_cache_create(dma_cmd_cache_name,
                                               sizeof(struct ccp_dma_cmd),
                                               sizeof(void *),
                                               SLAB_HWCACHE_ALIGN, NULL);
        if (!ccp->dma_cmd_cache)
                return -ENOMEM;

        dma_desc_cache_name = devm_kasprintf(ccp->dev, GFP_KERNEL,
                                             "%s-dmaengine-desc-cache",
                                             ccp->name);
        if (!dma_desc_cache_name) {
                ret = -ENOMEM;
                goto err_cache;
        }

        ccp->dma_desc_cache = kmem_cache_create(dma_desc_cache_name,
                                                sizeof(struct ccp_dma_desc),
                                                sizeof(void *),
                                                SLAB_HWCACHE_ALIGN, NULL);
        if (!ccp->dma_desc_cache) {
                ret = -ENOMEM;
                goto err_cache;
        }

        dma_dev->dev = ccp->dev;
        dma_dev->src_addr_widths = CCP_DMA_WIDTH(dma_get_mask(ccp->dev));
        dma_dev->dst_addr_widths = CCP_DMA_WIDTH(dma_get_mask(ccp->dev));
        dma_dev->directions = DMA_MEM_TO_MEM;
        dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
        dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
        dma_cap_set(DMA_INTERRUPT, dma_dev->cap_mask);

        /* The DMA channels for this device can be set to public or private,
         * and overridden by the module parameter dma_chan_attr.
         * Default: according to the value in vdata (dma_chan_attr=0)
         * dma_chan_attr=0x1: all channels private (override vdata)
         * dma_chan_attr=0x2: all channels public (override vdata)
         */
        if (ccp_get_dma_chan_attr(ccp) == DMA_PRIVATE)
                dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);

        INIT_LIST_HEAD(&dma_dev->channels);
        for (i = 0; i < ccp->cmd_q_count; i++) {
                chan = ccp->ccp_dma_chan + i;
                dma_chan = &chan->dma_chan;

                chan->ccp = ccp;

                spin_lock_init(&chan->lock);
                INIT_LIST_HEAD(&chan->created);
                INIT_LIST_HEAD(&chan->pending);
                INIT_LIST_HEAD(&chan->active);
                INIT_LIST_HEAD(&chan->complete);

                tasklet_init(&chan->cleanup_tasklet, ccp_do_cleanup,
                             (unsigned long)chan);

                dma_chan->device = dma_dev;
                dma_cookie_init(dma_chan);

                list_add_tail(&dma_chan->device_node, &dma_dev->channels);
        }

        dma_dev->device_free_chan_resources = ccp_free_chan_resources;
        dma_dev->device_prep_dma_memcpy = ccp_prep_dma_memcpy;
        dma_dev->device_prep_dma_interrupt = ccp_prep_dma_interrupt;
        dma_dev->device_issue_pending = ccp_issue_pending;
        dma_dev->device_tx_status = ccp_tx_status;
        dma_dev->device_pause = ccp_pause;
        dma_dev->device_resume = ccp_resume;
        dma_dev->device_terminate_all = ccp_terminate_all;

        ret = dma_async_device_register(dma_dev);
        if (ret)
                goto err_reg;

        return 0;

err_reg:
        kmem_cache_destroy(ccp->dma_desc_cache);

err_cache:
        kmem_cache_destroy(ccp->dma_cmd_cache);

        return ret;
}

void ccp_dmaengine_unregister(struct ccp_device *ccp)
{
        struct dma_device *dma_dev = &ccp->dma_dev;

        if (!dmaengine)
                return;

        dma_async_device_unregister(dma_dev);

        kmem_cache_destroy(ccp->dma_desc_cache);
        kmem_cache_destroy(ccp->dma_cmd_cache);
}