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/*
 * MOXA ART SoCs DMA Engine support.
 *
 * Copyright (C) 2013 Jonas Jensen
 *
 * Jonas Jensen <jonas.jensen@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_dma.h>
#include <linux/bitops.h>

#include <asm/cacheflush.h>

#include "dmaengine.h"
#include "virt-dma.h"

#define APB_DMA_MAX_CHANNEL			4

#define REG_OFF_ADDRESS_SOURCE			0
#define REG_OFF_ADDRESS_DEST			4
#define REG_OFF_CYCLES				8
#define REG_OFF_CTRL				12
#define REG_OFF_CHAN_SIZE			16

#define APB_DMA_ENABLE				BIT(0)
#define APB_DMA_FIN_INT_STS			BIT(1)
#define APB_DMA_FIN_INT_EN			BIT(2)
#define APB_DMA_BURST_MODE			BIT(3)
#define APB_DMA_ERR_INT_STS			BIT(4)
#define APB_DMA_ERR_INT_EN			BIT(5)

/*
 * Unset: APB
 * Set:   AHB
 */
#define APB_DMA_SOURCE_SELECT			0x40
#define APB_DMA_DEST_SELECT			0x80

#define APB_DMA_SOURCE				0x100
#define APB_DMA_DEST				0x1000

#define APB_DMA_SOURCE_MASK			0x700
#define APB_DMA_DEST_MASK			0x7000

/*
 * 000: No increment
 * 001: +1 (Burst=0), +4  (Burst=1)
 * 010: +2 (Burst=0), +8  (Burst=1)
 * 011: +4 (Burst=0), +16 (Burst=1)
 * 101: -1 (Burst=0), -4  (Burst=1)
 * 110: -2 (Burst=0), -8  (Burst=1)
 * 111: -4 (Burst=0), -16 (Burst=1)
 */
#define APB_DMA_SOURCE_INC_0			0
#define APB_DMA_SOURCE_INC_1_4			0x100
#define APB_DMA_SOURCE_INC_2_8			0x200
#define APB_DMA_SOURCE_INC_4_16			0x300
#define APB_DMA_SOURCE_DEC_1_4			0x500
#define APB_DMA_SOURCE_DEC_2_8			0x600
#define APB_DMA_SOURCE_DEC_4_16			0x700
#define APB_DMA_DEST_INC_0			0
#define APB_DMA_DEST_INC_1_4			0x1000
#define APB_DMA_DEST_INC_2_8			0x2000
#define APB_DMA_DEST_INC_4_16			0x3000
#define APB_DMA_DEST_DEC_1_4			0x5000
#define APB_DMA_DEST_DEC_2_8			0x6000
#define APB_DMA_DEST_DEC_4_16			0x7000

/*
 * Request signal select source/destination address for DMA hardware handshake.
 *
 * The request line number is a property of the DMA controller itself,
 * e.g. MMC must always request channels where dma_slave_config->slave_id is 5.
 *
 * 0:    No request / Grant signal
 * 1-15: Request    / Grant signal
 */
#define APB_DMA_SOURCE_REQ_NO			0x1000000
#define APB_DMA_SOURCE_REQ_NO_MASK		0xf000000
#define APB_DMA_DEST_REQ_NO			0x10000
#define APB_DMA_DEST_REQ_NO_MASK		0xf0000

#define APB_DMA_DATA_WIDTH			0x100000
#define APB_DMA_DATA_WIDTH_MASK			0x300000
/*
 * Data width of transfer:
 *
 * 00: Word
 * 01: Half
 * 10: Byte
 */
#define APB_DMA_DATA_WIDTH_4			0
#define APB_DMA_DATA_WIDTH_2			0x100000
#define APB_DMA_DATA_WIDTH_1			0x200000

#define APB_DMA_CYCLES_MASK			0x00ffffff

#define MOXART_DMA_DATA_TYPE_S8			0x00
#define MOXART_DMA_DATA_TYPE_S16		0x01
#define MOXART_DMA_DATA_TYPE_S32		0x02

struct moxart_sg {
	dma_addr_t addr;
	uint32_t len;
};

struct moxart_desc {
	enum dma_transfer_direction	dma_dir;
	dma_addr_t			dev_addr;
	unsigned int			sglen;
	unsigned int			dma_cycles;
	struct virt_dma_desc		vd;
	uint8_t				es;
	struct moxart_sg		sg[0];
};

struct moxart_chan {
	struct virt_dma_chan		vc;

	void __iomem			*base;
	struct moxart_desc		*desc;

	struct dma_slave_config		cfg;

	bool				allocated;
	bool				error;
	int				ch_num;
	unsigned int			line_reqno;
	unsigned int			sgidx;
};

struct moxart_dmadev {
	struct dma_device		dma_slave;
	struct moxart_chan		slave_chans[APB_DMA_MAX_CHANNEL];
};

struct moxart_filter_data {
	struct moxart_dmadev		*mdc;
	struct of_phandle_args		*dma_spec;
};

static const unsigned int es_bytes[] = {
	[MOXART_DMA_DATA_TYPE_S8] = 1,
	[MOXART_DMA_DATA_TYPE_S16] = 2,
	[MOXART_DMA_DATA_TYPE_S32] = 4,
};

static struct device *chan2dev(struct dma_chan *chan)
{
	return &chan->dev->device;
}

static inline struct moxart_chan *to_moxart_dma_chan(struct dma_chan *c)
{
	return container_of(c, struct moxart_chan, vc.chan);
}

static inline struct moxart_desc *to_moxart_dma_desc(
	struct dma_async_tx_descriptor *t)
{
	return container_of(t, struct moxart_desc, vd.tx);
}

static void moxart_dma_desc_free(struct virt_dma_desc *vd)
{
	kfree(container_of(vd, struct moxart_desc, vd));
}

static int moxart_terminate_all(struct dma_chan *chan)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);
	unsigned long flags;
	LIST_HEAD(head);
	u32 ctrl;

	dev_dbg(chan2dev(chan), "%s: ch=%p\n", __func__, ch);

	spin_lock_irqsave(&ch->vc.lock, flags);

	if (ch->desc)
		ch->desc = NULL;

	ctrl = readl(ch->base + REG_OFF_CTRL);
	ctrl &= ~(APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
	writel(ctrl, ch->base + REG_OFF_CTRL);

	vchan_get_all_descriptors(&ch->vc, &head);
	spin_unlock_irqrestore(&ch->vc.lock, flags);
	vchan_dma_desc_free_list(&ch->vc, &head);

	return 0;
}

static int moxart_slave_config(struct dma_chan *chan,
			       struct dma_slave_config *cfg)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);
	u32 ctrl;

	ch->cfg = *cfg;

	ctrl = readl(ch->base + REG_OFF_CTRL);
	ctrl |= APB_DMA_BURST_MODE;
	ctrl &= ~(APB_DMA_DEST_MASK | APB_DMA_SOURCE_MASK);
	ctrl &= ~(APB_DMA_DEST_REQ_NO_MASK | APB_DMA_SOURCE_REQ_NO_MASK);

	switch (ch->cfg.src_addr_width) {
	case DMA_SLAVE_BUSWIDTH_1_BYTE:
		ctrl |= APB_DMA_DATA_WIDTH_1;
		if (ch->cfg.direction != DMA_MEM_TO_DEV)
			ctrl |= APB_DMA_DEST_INC_1_4;
		else
			ctrl |= APB_DMA_SOURCE_INC_1_4;
		break;
	case DMA_SLAVE_BUSWIDTH_2_BYTES:
		ctrl |= APB_DMA_DATA_WIDTH_2;
		if (ch->cfg.direction != DMA_MEM_TO_DEV)
			ctrl |= APB_DMA_DEST_INC_2_8;
		else
			ctrl |= APB_DMA_SOURCE_INC_2_8;
		break;
	case DMA_SLAVE_BUSWIDTH_4_BYTES:
		ctrl &= ~APB_DMA_DATA_WIDTH;
		if (ch->cfg.direction != DMA_MEM_TO_DEV)
			ctrl |= APB_DMA_DEST_INC_4_16;
		else
			ctrl |= APB_DMA_SOURCE_INC_4_16;
		break;
	default:
		return -EINVAL;
	}

	if (ch->cfg.direction == DMA_MEM_TO_DEV) {
		ctrl &= ~APB_DMA_DEST_SELECT;
		ctrl |= APB_DMA_SOURCE_SELECT;
		ctrl |= (ch->line_reqno << 16 &
			 APB_DMA_DEST_REQ_NO_MASK);
	} else {
		ctrl |= APB_DMA_DEST_SELECT;
		ctrl &= ~APB_DMA_SOURCE_SELECT;
		ctrl |= (ch->line_reqno << 24 &
			 APB_DMA_SOURCE_REQ_NO_MASK);
	}

	writel(ctrl, ch->base + REG_OFF_CTRL);

	return 0;
}

static int moxart_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
			  unsigned long arg)
{
	int ret = 0;

	switch (cmd) {
	case DMA_PAUSE:
	case DMA_RESUME:
		return -EINVAL;
	case DMA_TERMINATE_ALL:
		moxart_terminate_all(chan);
		break;
	case DMA_SLAVE_CONFIG:
		ret = moxart_slave_config(chan, (struct dma_slave_config *)arg);
		break;
	default:
		ret = -ENOSYS;
	}

	return ret;
}

static struct dma_async_tx_descriptor *moxart_prep_slave_sg(
	struct dma_chan *chan, struct scatterlist *sgl,
	unsigned int sg_len, enum dma_transfer_direction dir,
	unsigned long tx_flags, void *context)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);
	struct moxart_desc *d;
	enum dma_slave_buswidth dev_width;
	dma_addr_t dev_addr;
	struct scatterlist *sgent;
	unsigned int es;
	unsigned int i;

	if (!is_slave_direction(dir)) {
		dev_err(chan2dev(chan), "%s: invalid DMA direction\n",
			__func__);
		return NULL;
	}

	if (dir == DMA_DEV_TO_MEM) {
		dev_addr = ch->cfg.src_addr;
		dev_width = ch->cfg.src_addr_width;
	} else {
		dev_addr = ch->cfg.dst_addr;
		dev_width = ch->cfg.dst_addr_width;
	}

	switch (dev_width) {
	case DMA_SLAVE_BUSWIDTH_1_BYTE:
		es = MOXART_DMA_DATA_TYPE_S8;
		break;
	case DMA_SLAVE_BUSWIDTH_2_BYTES:
		es = MOXART_DMA_DATA_TYPE_S16;
		break;
	case DMA_SLAVE_BUSWIDTH_4_BYTES:
		es = MOXART_DMA_DATA_TYPE_S32;
		break;
	default:
		dev_err(chan2dev(chan), "%s: unsupported data width (%u)\n",
			__func__, dev_width);
		return NULL;
	}

	d = kzalloc(sizeof(*d) + sg_len * sizeof(d->sg[0]), GFP_ATOMIC);
	if (!d)
		return NULL;

	d->dma_dir = dir;
	d->dev_addr = dev_addr;
	d->es = es;

	for_each_sg(sgl, sgent, sg_len, i) {
		d->sg[i].addr = sg_dma_address(sgent);
		d->sg[i].len = sg_dma_len(sgent);
	}

	d->sglen = sg_len;

	ch->error = 0;

	return vchan_tx_prep(&ch->vc, &d->vd, tx_flags);
}

static struct dma_chan *moxart_of_xlate(struct of_phandle_args *dma_spec,
					struct of_dma *ofdma)
{
	struct moxart_dmadev *mdc = ofdma->of_dma_data;
	struct dma_chan *chan;
	struct moxart_chan *ch;

	chan = dma_get_any_slave_channel(&mdc->dma_slave);
	if (!chan)
		return NULL;

	ch = to_moxart_dma_chan(chan);
	ch->line_reqno = dma_spec->args[0];

	return chan;
}

static int moxart_alloc_chan_resources(struct dma_chan *chan)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);

	dev_dbg(chan2dev(chan), "%s: allocating channel #%u\n",
		__func__, ch->ch_num);
	ch->allocated = 1;

	return 0;
}

static void moxart_free_chan_resources(struct dma_chan *chan)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);

	vchan_free_chan_resources(&ch->vc);

	dev_dbg(chan2dev(chan), "%s: freeing channel #%u\n",
		__func__, ch->ch_num);
	ch->allocated = 0;
}

static void moxart_dma_set_params(struct moxart_chan *ch, dma_addr_t src_addr,
				  dma_addr_t dst_addr)
{
	writel(src_addr, ch->base + REG_OFF_ADDRESS_SOURCE);
	writel(dst_addr, ch->base + REG_OFF_ADDRESS_DEST);
}

static void moxart_set_transfer_params(struct moxart_chan *ch, unsigned int len)
{
	struct moxart_desc *d = ch->desc;
	unsigned int sglen_div = es_bytes[d->es];

	d->dma_cycles = len >> sglen_div;

	/*
	 * There are 4 cycles on 64 bytes copied, i.e. one cycle copies 16
	 * bytes ( when width is APB_DMAB_DATA_WIDTH_4 ).
	 */
	writel(d->dma_cycles, ch->base + REG_OFF_CYCLES);

	dev_dbg(chan2dev(&ch->vc.chan), "%s: set %u DMA cycles (len=%u)\n",
		__func__, d->dma_cycles, len);
}

static void moxart_start_dma(struct moxart_chan *ch)
{
	u32 ctrl;

	ctrl = readl(ch->base + REG_OFF_CTRL);
	ctrl |= (APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
	writel(ctrl, ch->base + REG_OFF_CTRL);
}

static void moxart_dma_start_sg(struct moxart_chan *ch, unsigned int idx)
{
	struct moxart_desc *d = ch->desc;
	struct moxart_sg *sg = ch->desc->sg + idx;

	if (ch->desc->dma_dir == DMA_MEM_TO_DEV)
		moxart_dma_set_params(ch, sg->addr, d->dev_addr);
	else if (ch->desc->dma_dir == DMA_DEV_TO_MEM)
		moxart_dma_set_params(ch, d->dev_addr, sg->addr);

	moxart_set_transfer_params(ch, sg->len);

	moxart_start_dma(ch);
}

static void moxart_dma_start_desc(struct dma_chan *chan)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);
	struct virt_dma_desc *vd;

	vd = vchan_next_desc(&ch->vc);

	if (!vd) {
		ch->desc = NULL;
		return;
	}

	list_del(&vd->node);

	ch->desc = to_moxart_dma_desc(&vd->tx);
	ch->sgidx = 0;

	moxart_dma_start_sg(ch, 0);
}

static void moxart_issue_pending(struct dma_chan *chan)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);
	unsigned long flags;

	spin_lock_irqsave(&ch->vc.lock, flags);
	if (vchan_issue_pending(&ch->vc) && !ch->desc)
		moxart_dma_start_desc(chan);
	spin_unlock_irqrestore(&ch->vc.lock, flags);
}

static size_t moxart_dma_desc_size(struct moxart_desc *d,
				   unsigned int completed_sgs)
{
	unsigned int i;
	size_t size;

	for (size = i = completed_sgs; i < d->sglen; i++)
		size += d->sg[i].len;

	return size;
}

static size_t moxart_dma_desc_size_in_flight(struct moxart_chan *ch)
{
	size_t size;
	unsigned int completed_cycles, cycles;

	size = moxart_dma_desc_size(ch->desc, ch->sgidx);
	cycles = readl(ch->base + REG_OFF_CYCLES);
	completed_cycles = (ch->desc->dma_cycles - cycles);
	size -= completed_cycles << es_bytes[ch->desc->es];

	dev_dbg(chan2dev(&ch->vc.chan), "%s: size=%zu\n", __func__, size);

	return size;
}

static enum dma_status moxart_tx_status(struct dma_chan *chan,
					dma_cookie_t cookie,
					struct dma_tx_state *txstate)
{
	struct moxart_chan *ch = to_moxart_dma_chan(chan);
	struct virt_dma_desc *vd;
	struct moxart_desc *d;
	enum dma_status ret;
	unsigned long flags;

	/*
	 * dma_cookie_status() assigns initial residue value.
	 */
	ret = dma_cookie_status(chan, cookie, txstate);

	spin_lock_irqsave(&ch->vc.lock, flags);
	vd = vchan_find_desc(&ch->vc, cookie);
	if (vd) {
		d = to_moxart_dma_desc(&vd->tx);
		txstate->residue = moxart_dma_desc_size(d, 0);
	} else if (ch->desc && ch->desc->vd.tx.cookie == cookie) {
		txstate->residue = moxart_dma_desc_size_in_flight(ch);
	}
	spin_unlock_irqrestore(&ch->vc.lock, flags);

	if (ch->error)
		return DMA_ERROR;

	return ret;
}

static void moxart_dma_init(struct dma_device *dma, struct device *dev)
{
	dma->device_prep_slave_sg		= moxart_prep_slave_sg;
	dma->device_alloc_chan_resources	= moxart_alloc_chan_resources;
	dma->device_free_chan_resources		= moxart_free_chan_resources;
	dma->device_issue_pending		= moxart_issue_pending;
	dma->device_tx_status			= moxart_tx_status;
	dma->device_control			= moxart_control;
	dma->dev				= dev;

	INIT_LIST_HEAD(&dma->channels);
}

static irqreturn_t moxart_dma_interrupt(int irq, void *devid)
{
	struct moxart_dmadev *mc = devid;
	struct moxart_chan *ch = &mc->slave_chans[0];
	unsigned int i;
	unsigned long flags;
	u32 ctrl;

	dev_dbg(chan2dev(&ch->vc.chan), "%s\n", __func__);

	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
		if (!ch->allocated)
			continue;

		ctrl = readl(ch->base + REG_OFF_CTRL);

		dev_dbg(chan2dev(&ch->vc.chan), "%s: ch=%p ch->base=%p ctrl=%x\n",
			__func__, ch, ch->base, ctrl);

		if (ctrl & APB_DMA_FIN_INT_STS) {
			ctrl &= ~APB_DMA_FIN_INT_STS;
			if (ch->desc) {
				spin_lock_irqsave(&ch->vc.lock, flags);
				if (++ch->sgidx < ch->desc->sglen) {
					moxart_dma_start_sg(ch, ch->sgidx);
				} else {
					vchan_cookie_complete(&ch->desc->vd);
					moxart_dma_start_desc(&ch->vc.chan);
				}
				spin_unlock_irqrestore(&ch->vc.lock, flags);
			}
		}

		if (ctrl & APB_DMA_ERR_INT_STS) {
			ctrl &= ~APB_DMA_ERR_INT_STS;
			ch->error = 1;
		}

		writel(ctrl, ch->base + REG_OFF_CTRL);
	}

	return IRQ_HANDLED;
}

static int moxart_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *node = dev->of_node;
	struct resource *res;
	static void __iomem *dma_base_addr;
	int ret, i;
	unsigned int irq;
	struct moxart_chan *ch;
	struct moxart_dmadev *mdc;

	mdc = devm_kzalloc(dev, sizeof(*mdc), GFP_KERNEL);
	if (!mdc) {
		dev_err(dev, "can't allocate DMA container\n");
		return -ENOMEM;
	}

	irq = irq_of_parse_and_map(node, 0);
	if (irq == NO_IRQ) {
		dev_err(dev, "no IRQ resource\n");
		return -EINVAL;
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	dma_base_addr = devm_ioremap_resource(dev, res);
	if (IS_ERR(dma_base_addr))
		return PTR_ERR(dma_base_addr);

	dma_cap_zero(mdc->dma_slave.cap_mask);
	dma_cap_set(DMA_SLAVE, mdc->dma_slave.cap_mask);
	dma_cap_set(DMA_PRIVATE, mdc->dma_slave.cap_mask);

	moxart_dma_init(&mdc->dma_slave, dev);

	ch = &mdc->slave_chans[0];
	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
		ch->ch_num = i;
		ch->base = dma_base_addr + i * REG_OFF_CHAN_SIZE;
		ch->allocated = 0;

		ch->vc.desc_free = moxart_dma_desc_free;
		vchan_init(&ch->vc, &mdc->dma_slave);

		dev_dbg(dev, "%s: chs[%d]: ch->ch_num=%u ch->base=%p\n",
			__func__, i, ch->ch_num, ch->base);
	}

	platform_set_drvdata(pdev, mdc);

	ret = devm_request_irq(dev, irq, moxart_dma_interrupt, 0,
			       "moxart-dma-engine", mdc);
	if (ret) {
		dev_err(dev, "devm_request_irq failed\n");
		return ret;
	}

	ret = dma_async_device_register(&mdc->dma_slave);
	if (ret) {
		dev_err(dev, "dma_async_device_register failed\n");
		return ret;
	}

	ret = of_dma_controller_register(node, moxart_of_xlate, mdc);
	if (ret) {
		dev_err(dev, "of_dma_controller_register failed\n");
		dma_async_device_unregister(&mdc->dma_slave);
		return ret;
	}

	dev_dbg(dev, "%s: IRQ=%u\n", __func__, irq);

	return 0;
}

static int moxart_remove(struct platform_device *pdev)
{
	struct moxart_dmadev *m = platform_get_drvdata(pdev);

	dma_async_device_unregister(&m->dma_slave);

	if (pdev->dev.of_node)
		of_dma_controller_free(pdev->dev.of_node);

	return 0;
}

static const struct of_device_id moxart_dma_match[] = {
	{ .compatible = "moxa,moxart-dma" },
	{ }
};

static struct platform_driver moxart_driver = {
	.probe	= moxart_probe,
	.remove	= moxart_remove,
	.driver = {
		.name		= "moxart-dma-engine",
		.owner		= THIS_MODULE,
		.of_match_table	= moxart_dma_match,
	},
};

static int moxart_init(void)
{
	return platform_driver_register(&moxart_driver);
}
subsys_initcall(moxart_init);

static void __exit moxart_exit(void)
{
	platform_driver_unregister(&moxart_driver);
}
module_exit(moxart_exit);

MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
MODULE_DESCRIPTION("MOXART DMA engine driver");
MODULE_LICENSE("GPL v2");