// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * SiFive FU540 Platform DMA driver
 * Copyright (C) 2019 SiFive
 *
 * Based partially on:
 * - drivers/dma/fsl-edma.c
 * - drivers/dma/dw-edma/
 * - drivers/dma/pxa-dma.c
 *
 * See the following sources for further documentation:
 * - Chapter 12 "Platform DMA Engine (PDMA)" of
 *   SiFive FU540-C000 v1.0
 *   https://static.dev.sifive.com/FU540-C000-v1.0.pdf
 */
#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>
#include <linux/dma-mapping.h>
#include <linux/of.h>
#include <linux/slab.h>

#include "sf-pdma.h"

#ifndef readq
static inline unsigned long long readq(void __iomem *addr)
{
        return readl(addr) | (((unsigned long long)readl(addr + 4)) << 32LL);
}
#endif

#ifndef writeq
static inline void writeq(unsigned long long v, void __iomem *addr)
{
        writel(lower_32_bits(v), addr);
        writel(upper_32_bits(v), addr + 4);
}
#endif

static inline struct sf_pdma_chan *to_sf_pdma_chan(struct dma_chan *dchan)
{
        return container_of(dchan, struct sf_pdma_chan, vchan.chan);
}

static inline struct sf_pdma_desc *to_sf_pdma_desc(struct virt_dma_desc *vd)
{
        return container_of(vd, struct sf_pdma_desc, vdesc);
}

static struct sf_pdma_desc *sf_pdma_alloc_desc(struct sf_pdma_chan *chan)
{
        struct sf_pdma_desc *desc;
        unsigned long flags;

        spin_lock_irqsave(&chan->lock, flags);

        if (chan->desc && !chan->desc->in_use) {
                spin_unlock_irqrestore(&chan->lock, flags);
                return chan->desc;
        }

        spin_unlock_irqrestore(&chan->lock, flags);

        desc = kzalloc(sizeof(*desc), GFP_NOWAIT);
        if (!desc)
                return NULL;

        desc->chan = chan;

        return desc;
}

static void sf_pdma_fill_desc(struct sf_pdma_desc *desc,
                              u64 dst, u64 src, u64 size)
{
        desc->xfer_type = PDMA_FULL_SPEED;
        desc->xfer_size = size;
        desc->dst_addr = dst;
        desc->src_addr = src;
}

static void sf_pdma_disclaim_chan(struct sf_pdma_chan *chan)
{
        struct pdma_regs *regs = &chan->regs;

        writel(PDMA_CLEAR_CTRL, regs->ctrl);
}

static struct dma_async_tx_descriptor *
sf_pdma_prep_dma_memcpy(struct dma_chan *dchan, dma_addr_t dest, dma_addr_t src,
                        size_t len, unsigned long flags)
{
        struct sf_pdma_chan *chan = to_sf_pdma_chan(dchan);
        struct sf_pdma_desc *desc;
        unsigned long iflags;

        if (chan && (!len || !dest || !src)) {
                dev_err(chan->pdma->dma_dev.dev,
                        "Please check dma len, dest, src!\n");
                return NULL;
        }

        desc = sf_pdma_alloc_desc(chan);
        if (!desc)
                return NULL;

        desc->in_use = true;
        desc->dirn = DMA_MEM_TO_MEM;
        desc->async_tx = vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);

        spin_lock_irqsave(&chan->vchan.lock, iflags);
        chan->desc = desc;
        sf_pdma_fill_desc(desc, dest, src, len);
        spin_unlock_irqrestore(&chan->vchan.lock, iflags);

        return desc->async_tx;
}

static int sf_pdma_slave_config(struct dma_chan *dchan,
                                struct dma_slave_config *cfg)
{
        struct sf_pdma_chan *chan = to_sf_pdma_chan(dchan);

        memcpy(&chan->cfg, cfg, sizeof(*cfg));

        return 0;
}

static int sf_pdma_alloc_chan_resources(struct dma_chan *dchan)
{
        struct sf_pdma_chan *chan = to_sf_pdma_chan(dchan);
        struct pdma_regs *regs = &chan->regs;

        dma_cookie_init(dchan);
        writel(PDMA_CLAIM_MASK, regs->ctrl);

        return 0;
}

static void sf_pdma_disable_request(struct sf_pdma_chan *chan)
{
        struct pdma_regs *regs = &chan->regs;

        writel(readl(regs->ctrl) & ~PDMA_RUN_MASK, regs->ctrl);
}

static void sf_pdma_free_chan_resources(struct dma_chan *dchan)
{
        struct sf_pdma_chan *chan = to_sf_pdma_chan(dchan);
        unsigned long flags;
        LIST_HEAD(head);

        spin_lock_irqsave(&chan->vchan.lock, flags);
        sf_pdma_disable_request(chan);
        kfree(chan->desc);
        chan->desc = NULL;
        vchan_get_all_descriptors(&chan->vchan, &head);
        sf_pdma_disclaim_chan(chan);
        spin_unlock_irqrestore(&chan->vchan.lock, flags);
        vchan_dma_desc_free_list(&chan->vchan, &head);
}

static size_t sf_pdma_desc_residue(struct sf_pdma_chan *chan,
                                   dma_cookie_t cookie)
{
        struct virt_dma_desc *vd = NULL;
        struct pdma_regs *regs = &chan->regs;
        unsigned long flags;
        u64 residue = 0;
        struct sf_pdma_desc *desc;
        struct dma_async_tx_descriptor *tx;

        spin_lock_irqsave(&chan->vchan.lock, flags);

        tx = &chan->desc->vdesc.tx;
        if (cookie == tx->chan->completed_cookie)
                goto out;

        if (cookie == tx->cookie) {
                residue = readq(regs->residue);
        } else {
                vd = vchan_find_desc(&chan->vchan, cookie);
                if (!vd)
                        goto out;

                desc = to_sf_pdma_desc(vd);
                residue = desc->xfer_size;
        }

out:
        spin_unlock_irqrestore(&chan->vchan.lock, flags);
        return residue;
}

static enum dma_status
sf_pdma_tx_status(struct dma_chan *dchan,
                  dma_cookie_t cookie,
                  struct dma_tx_state *txstate)
{
        struct sf_pdma_chan *chan = to_sf_pdma_chan(dchan);
        enum dma_status status;

        status = dma_cookie_status(dchan, cookie, txstate);

        if (txstate && status != DMA_ERROR)
                dma_set_residue(txstate, sf_pdma_desc_residue(chan, cookie));

        return status;
}

static int sf_pdma_terminate_all(struct dma_chan *dchan)
{
        struct sf_pdma_chan *chan = to_sf_pdma_chan(dchan);
        unsigned long flags;
        LIST_HEAD(head);

        spin_lock_irqsave(&chan->vchan.lock, flags);
        sf_pdma_disable_request(chan);
        kfree(chan->desc);
        chan->desc = NULL;
        chan->xfer_err = false;
        vchan_get_all_descriptors(&chan->vchan, &head);
        spin_unlock_irqrestore(&chan->vchan.lock, flags);
        vchan_dma_desc_free_list(&chan->vchan, &head);

        return 0;
}

static void sf_pdma_enable_request(struct sf_pdma_chan *chan)
{
        struct pdma_regs *regs = &chan->regs;
        u32 v;

        v = PDMA_CLAIM_MASK |
                PDMA_ENABLE_DONE_INT_MASK |
                PDMA_ENABLE_ERR_INT_MASK |
                PDMA_RUN_MASK;

        writel(v, regs->ctrl);
}

static void sf_pdma_xfer_desc(struct sf_pdma_chan *chan)
{
        struct sf_pdma_desc *desc = chan->desc;
        struct pdma_regs *regs = &chan->regs;

        if (!desc) {
                dev_err(chan->pdma->dma_dev.dev, "NULL desc.\n");
                return;
        }

        writel(desc->xfer_type, regs->xfer_type);
        writeq(desc->xfer_size, regs->xfer_size);
        writeq(desc->dst_addr, regs->dst_addr);
        writeq(desc->src_addr, regs->src_addr);

        chan->desc = desc;
        chan->status = DMA_IN_PROGRESS;
        sf_pdma_enable_request(chan);
}

static void sf_pdma_issue_pending(struct dma_chan *dchan)
{
        struct sf_pdma_chan *chan = to_sf_pdma_chan(dchan);
        unsigned long flags;

        spin_lock_irqsave(&chan->vchan.lock, flags);

        if (vchan_issue_pending(&chan->vchan) && chan->desc)
                sf_pdma_xfer_desc(chan);

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

static void sf_pdma_free_desc(struct virt_dma_desc *vdesc)
{
        struct sf_pdma_desc *desc;

        desc = to_sf_pdma_desc(vdesc);
        desc->in_use = false;
}

static void sf_pdma_donebh_tasklet(struct tasklet_struct *t)
{
        struct sf_pdma_chan *chan = from_tasklet(chan, t, done_tasklet);
        unsigned long flags;

        spin_lock_irqsave(&chan->lock, flags);
        if (chan->xfer_err) {
                chan->retries = MAX_RETRY;
                chan->status = DMA_COMPLETE;
                chan->xfer_err = false;
        }
        spin_unlock_irqrestore(&chan->lock, flags);

        spin_lock_irqsave(&chan->vchan.lock, flags);
        list_del(&chan->desc->vdesc.node);
        vchan_cookie_complete(&chan->desc->vdesc);
        spin_unlock_irqrestore(&chan->vchan.lock, flags);
}

static void sf_pdma_errbh_tasklet(struct tasklet_struct *t)
{
        struct sf_pdma_chan *chan = from_tasklet(chan, t, err_tasklet);
        struct sf_pdma_desc *desc = chan->desc;
        unsigned long flags;

        spin_lock_irqsave(&chan->lock, flags);
        if (chan->retries <= 0) {
                /* fail to recover */
                spin_unlock_irqrestore(&chan->lock, flags);
                dmaengine_desc_get_callback_invoke(desc->async_tx, NULL);
        } else {
                /* retry */
                chan->retries--;
                chan->xfer_err = true;
                chan->status = DMA_ERROR;

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

static irqreturn_t sf_pdma_done_isr(int irq, void *dev_id)
{
        struct sf_pdma_chan *chan = dev_id;
        struct pdma_regs *regs = &chan->regs;
        u64 residue;

        spin_lock(&chan->vchan.lock);
        writel((readl(regs->ctrl)) & ~PDMA_DONE_STATUS_MASK, regs->ctrl);
        residue = readq(regs->residue);

        if (!residue) {
                tasklet_hi_schedule(&chan->done_tasklet);
        } else {
                /* submit next trascatioin if possible */
                struct sf_pdma_desc *desc = chan->desc;

                desc->src_addr += desc->xfer_size - residue;
                desc->dst_addr += desc->xfer_size - residue;
                desc->xfer_size = residue;

                sf_pdma_xfer_desc(chan);
        }

        spin_unlock(&chan->vchan.lock);

        return IRQ_HANDLED;
}

static irqreturn_t sf_pdma_err_isr(int irq, void *dev_id)
{
        struct sf_pdma_chan *chan = dev_id;
        struct pdma_regs *regs = &chan->regs;

        spin_lock(&chan->lock);
        writel((readl(regs->ctrl)) & ~PDMA_ERR_STATUS_MASK, regs->ctrl);
        spin_unlock(&chan->lock);

        tasklet_schedule(&chan->err_tasklet);

        return IRQ_HANDLED;
}

/**
 * sf_pdma_irq_init() - Init PDMA IRQ Handlers
 * @pdev: pointer of platform_device
 * @pdma: pointer of PDMA engine. Caller should check NULL
 *
 * Initialize DONE and ERROR interrupt handler for 4 channels. Caller should
 * make sure the pointer passed in are non-NULL. This function should be called
 * only one time during the device probe.
 *
 * Context: Any context.
 *
 * Return:
 * * 0          - OK to init all IRQ handlers
 * * -EINVAL    - Fail to request IRQ
 */
static int sf_pdma_irq_init(struct platform_device *pdev, struct sf_pdma *pdma)
{
        int irq, r, i;
        struct sf_pdma_chan *chan;

        for (i = 0; i < pdma->n_chans; i++) {
                chan = &pdma->chans[i];

                irq = platform_get_irq(pdev, i * 2);
                if (irq < 0) {
                        dev_err(&pdev->dev, "ch(%d) Can't get done irq.\n", i);
                        return -EINVAL;
                }

                r = devm_request_irq(&pdev->dev, irq, sf_pdma_done_isr, 0,
                                     dev_name(&pdev->dev), (void *)chan);
                if (r) {
                        dev_err(&pdev->dev, "Fail to attach done ISR: %d\n", r);
                        return -EINVAL;
                }

                chan->txirq = irq;

                irq = platform_get_irq(pdev, (i * 2) + 1);
                if (irq < 0) {
                        dev_err(&pdev->dev, "ch(%d) Can't get err irq.\n", i);
                        return -EINVAL;
                }

                r = devm_request_irq(&pdev->dev, irq, sf_pdma_err_isr, 0,
                                     dev_name(&pdev->dev), (void *)chan);
                if (r) {
                        dev_err(&pdev->dev, "Fail to attach err ISR: %d\n", r);
                        return -EINVAL;
                }

                chan->errirq = irq;
        }

        return 0;
}

/**
 * sf_pdma_setup_chans() - Init settings of each channel
 * @pdma: pointer of PDMA engine. Caller should check NULL
 *
 * Initialize all data structure and register base. Caller should make sure
 * the pointer passed in are non-NULL. This function should be called only
 * one time during the device probe.
 *
 * Context: Any context.
 *
 * Return: none
 */
static void sf_pdma_setup_chans(struct sf_pdma *pdma)
{
        int i;
        struct sf_pdma_chan *chan;

        INIT_LIST_HEAD(&pdma->dma_dev.channels);

        for (i = 0; i < pdma->n_chans; i++) {
                chan = &pdma->chans[i];

                chan->regs.ctrl =
                        SF_PDMA_REG_BASE(i) + PDMA_CTRL;
                chan->regs.xfer_type =
                        SF_PDMA_REG_BASE(i) + PDMA_XFER_TYPE;
                chan->regs.xfer_size =
                        SF_PDMA_REG_BASE(i) + PDMA_XFER_SIZE;
                chan->regs.dst_addr =
                        SF_PDMA_REG_BASE(i) + PDMA_DST_ADDR;
                chan->regs.src_addr =
                        SF_PDMA_REG_BASE(i) + PDMA_SRC_ADDR;
                chan->regs.act_type =
                        SF_PDMA_REG_BASE(i) + PDMA_ACT_TYPE;
                chan->regs.residue =
                        SF_PDMA_REG_BASE(i) + PDMA_REMAINING_BYTE;
                chan->regs.cur_dst_addr =
                        SF_PDMA_REG_BASE(i) + PDMA_CUR_DST_ADDR;
                chan->regs.cur_src_addr =
                        SF_PDMA_REG_BASE(i) + PDMA_CUR_SRC_ADDR;

                chan->pdma = pdma;
                chan->pm_state = RUNNING;
                chan->slave_id = i;
                chan->xfer_err = false;
                spin_lock_init(&chan->lock);

                chan->vchan.desc_free = sf_pdma_free_desc;
                vchan_init(&chan->vchan, &pdma->dma_dev);

                writel(PDMA_CLEAR_CTRL, chan->regs.ctrl);

                tasklet_setup(&chan->done_tasklet, sf_pdma_donebh_tasklet);
                tasklet_setup(&chan->err_tasklet, sf_pdma_errbh_tasklet);
        }
}

static int sf_pdma_probe(struct platform_device *pdev)
{
        struct sf_pdma *pdma;
        struct sf_pdma_chan *chan;
        struct resource *res;
        int len, chans;
        int ret;
        const enum dma_slave_buswidth widths =
                DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
                DMA_SLAVE_BUSWIDTH_4_BYTES | DMA_SLAVE_BUSWIDTH_8_BYTES |
                DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
                DMA_SLAVE_BUSWIDTH_64_BYTES;

        chans = PDMA_NR_CH;
        len = sizeof(*pdma) + sizeof(*chan) * chans;
        pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
        if (!pdma)
                return -ENOMEM;

        pdma->n_chans = chans;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        pdma->membase = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(pdma->membase))
                return PTR_ERR(pdma->membase);

        ret = sf_pdma_irq_init(pdev, pdma);
        if (ret)
                return ret;

        sf_pdma_setup_chans(pdma);

        pdma->dma_dev.dev = &pdev->dev;

        /* Setup capability */
        dma_cap_set(DMA_MEMCPY, pdma->dma_dev.cap_mask);
        pdma->dma_dev.copy_align = 2;
        pdma->dma_dev.src_addr_widths = widths;
        pdma->dma_dev.dst_addr_widths = widths;
        pdma->dma_dev.directions = BIT(DMA_MEM_TO_MEM);
        pdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
        pdma->dma_dev.descriptor_reuse = true;

        /* Setup DMA APIs */
        pdma->dma_dev.device_alloc_chan_resources =
                sf_pdma_alloc_chan_resources;
        pdma->dma_dev.device_free_chan_resources =
                sf_pdma_free_chan_resources;
        pdma->dma_dev.device_tx_status = sf_pdma_tx_status;
        pdma->dma_dev.device_prep_dma_memcpy = sf_pdma_prep_dma_memcpy;
        pdma->dma_dev.device_config = sf_pdma_slave_config;
        pdma->dma_dev.device_terminate_all = sf_pdma_terminate_all;
        pdma->dma_dev.device_issue_pending = sf_pdma_issue_pending;

        platform_set_drvdata(pdev, pdma);

        ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
        if (ret)
                dev_warn(&pdev->dev,
                         "Failed to set DMA mask. Fall back to default.\n");

        ret = dma_async_device_register(&pdma->dma_dev);
        if (ret) {
                dev_err(&pdev->dev,
                        "Can't register SiFive Platform DMA. (%d)\n", ret);
                return ret;
        }

        return 0;
}

static int sf_pdma_remove(struct platform_device *pdev)
{
        struct sf_pdma *pdma = platform_get_drvdata(pdev);
        struct sf_pdma_chan *ch;
        int i;

        for (i = 0; i < PDMA_NR_CH; i++) {
                ch = &pdma->chans[i];

                devm_free_irq(&pdev->dev, ch->txirq, ch);
                devm_free_irq(&pdev->dev, ch->errirq, ch);
                list_del(&ch->vchan.chan.device_node);
                tasklet_kill(&ch->vchan.task);
                tasklet_kill(&ch->done_tasklet);
                tasklet_kill(&ch->err_tasklet);
        }

        dma_async_device_unregister(&pdma->dma_dev);

        return 0;
}

static const struct of_device_id sf_pdma_dt_ids[] = {
        { .compatible = "sifive,fu540-c000-pdma" },
        {},
};
MODULE_DEVICE_TABLE(of, sf_pdma_dt_ids);

static struct platform_driver sf_pdma_driver = {
        .probe          = sf_pdma_probe,
        .remove         = sf_pdma_remove,
        .driver         = {
                .name   = "sf-pdma",
                .of_match_table = sf_pdma_dt_ids,
        },
};

static int __init sf_pdma_init(void)
{
        return platform_driver_register(&sf_pdma_driver);
}

static void __exit sf_pdma_exit(void)
{
        platform_driver_unregister(&sf_pdma_driver);
}

/* do early init */
subsys_initcall(sf_pdma_init);
module_exit(sf_pdma_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("SiFive Platform DMA driver");
MODULE_AUTHOR("Green Wan <green.wan@sifive.com>");