dmaengine: Add driver for IMG MDC

Add support for the IMG Multi-threaded DMA Controller (MDC) found on
certain IMG SoCs.  Currently this driver supports the variant present
on the MIPS-based Pistachio SoC.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/Kconfig

@@ -416,6 +416,15 @@ config NBPFAXI_DMA
 	help
 	  Support for "Type-AXI" NBPF DMA IPs from Renesas
 
+config IMG_MDC_DMA
+	tristate "IMG MDC support"
+	depends on MIPS || COMPILE_TEST
+	depends on MFD_SYSCON
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the IMG multi-threaded DMA controller (MDC).
+
 config DMA_ENGINE
 	bool
 

drivers/dma/Makefile

@@ -50,3 +50,4 @@ obj-y += xilinx/
 obj-$(CONFIG_INTEL_MIC_X100_DMA) += mic_x100_dma.o
 obj-$(CONFIG_NBPFAXI_DMA) += nbpfaxi.o
 obj-$(CONFIG_DMA_SUN6I) += sun6i-dma.o
+obj-$(CONFIG_IMG_MDC_DMA) += img-mdc-dma.o

drivers/dma/img-mdc-dma.c

@@ -0,0 +1,1011 @@
+/*
+ * IMG Multi-threaded DMA Controller (MDC)
+ *
+ * Copyright (C) 2009,2012,2013 Imagination Technologies Ltd.
+ * Copyright (C) 2014 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "dmaengine.h"
+#include "virt-dma.h"
+
+#define MDC_MAX_DMA_CHANNELS			32
+
+#define MDC_GENERAL_CONFIG			0x000
+#define MDC_GENERAL_CONFIG_LIST_IEN		BIT(31)
+#define MDC_GENERAL_CONFIG_IEN			BIT(29)
+#define MDC_GENERAL_CONFIG_LEVEL_INT		BIT(28)
+#define MDC_GENERAL_CONFIG_INC_W		BIT(12)
+#define MDC_GENERAL_CONFIG_INC_R		BIT(8)
+#define MDC_GENERAL_CONFIG_PHYSICAL_W		BIT(7)
+#define MDC_GENERAL_CONFIG_WIDTH_W_SHIFT	4
+#define MDC_GENERAL_CONFIG_WIDTH_W_MASK		0x7
+#define MDC_GENERAL_CONFIG_PHYSICAL_R		BIT(3)
+#define MDC_GENERAL_CONFIG_WIDTH_R_SHIFT	0
+#define MDC_GENERAL_CONFIG_WIDTH_R_MASK		0x7
+
+#define MDC_READ_PORT_CONFIG			0x004
+#define MDC_READ_PORT_CONFIG_STHREAD_SHIFT	28
+#define MDC_READ_PORT_CONFIG_STHREAD_MASK	0xf
+#define MDC_READ_PORT_CONFIG_RTHREAD_SHIFT	24
+#define MDC_READ_PORT_CONFIG_RTHREAD_MASK	0xf
+#define MDC_READ_PORT_CONFIG_WTHREAD_SHIFT	16
+#define MDC_READ_PORT_CONFIG_WTHREAD_MASK	0xf
+#define MDC_READ_PORT_CONFIG_BURST_SIZE_SHIFT	4
+#define MDC_READ_PORT_CONFIG_BURST_SIZE_MASK	0xff
+#define MDC_READ_PORT_CONFIG_DREQ_ENABLE	BIT(1)
+
+#define MDC_READ_ADDRESS			0x008
+
+#define MDC_WRITE_ADDRESS			0x00c
+
+#define MDC_TRANSFER_SIZE			0x010
+#define MDC_TRANSFER_SIZE_MASK			0xffffff
+
+#define MDC_LIST_NODE_ADDRESS			0x014
+
+#define MDC_CMDS_PROCESSED			0x018
+#define MDC_CMDS_PROCESSED_CMDS_PROCESSED_SHIFT	16
+#define MDC_CMDS_PROCESSED_CMDS_PROCESSED_MASK	0x3f
+#define MDC_CMDS_PROCESSED_INT_ACTIVE		BIT(8)
+#define MDC_CMDS_PROCESSED_CMDS_DONE_SHIFT	0
+#define MDC_CMDS_PROCESSED_CMDS_DONE_MASK	0x3f
+
+#define MDC_CONTROL_AND_STATUS			0x01c
+#define MDC_CONTROL_AND_STATUS_CANCEL		BIT(20)
+#define MDC_CONTROL_AND_STATUS_LIST_EN		BIT(4)
+#define MDC_CONTROL_AND_STATUS_EN		BIT(0)
+
+#define MDC_ACTIVE_TRANSFER_SIZE		0x030
+
+#define MDC_GLOBAL_CONFIG_A				0x900
+#define MDC_GLOBAL_CONFIG_A_THREAD_ID_WIDTH_SHIFT	16
+#define MDC_GLOBAL_CONFIG_A_THREAD_ID_WIDTH_MASK	0xff
+#define MDC_GLOBAL_CONFIG_A_DMA_CONTEXTS_SHIFT		8
+#define MDC_GLOBAL_CONFIG_A_DMA_CONTEXTS_MASK		0xff
+#define MDC_GLOBAL_CONFIG_A_SYS_DAT_WIDTH_SHIFT		0
+#define MDC_GLOBAL_CONFIG_A_SYS_DAT_WIDTH_MASK		0xff
+
+struct mdc_hw_list_desc {
+	u32 gen_conf;
+	u32 readport_conf;
+	u32 read_addr;
+	u32 write_addr;
+	u32 xfer_size;
+	u32 node_addr;
+	u32 cmds_done;
+	u32 ctrl_status;
+	/*
+	 * Not part of the list descriptor, but instead used by the CPU to
+	 * traverse the list.
+	 */
+	struct mdc_hw_list_desc *next_desc;
+};
+
+struct mdc_tx_desc {
+	struct mdc_chan *chan;
+	struct virt_dma_desc vd;
+	dma_addr_t list_phys;
+	struct mdc_hw_list_desc *list;
+	bool cyclic;
+	bool cmd_loaded;
+	unsigned int list_len;
+	unsigned int list_period_len;
+	size_t list_xfer_size;
+	unsigned int list_cmds_done;
+};
+
+struct mdc_chan {
+	struct mdc_dma *mdma;
+	struct virt_dma_chan vc;
+	struct dma_slave_config config;
+	struct mdc_tx_desc *desc;
+	int irq;
+	unsigned int periph;
+	unsigned int thread;
+	unsigned int chan_nr;
+};
+
+struct mdc_dma_soc_data {
+	void (*enable_chan)(struct mdc_chan *mchan);
+	void (*disable_chan)(struct mdc_chan *mchan);
+};
+
+struct mdc_dma {
+	struct dma_device dma_dev;
+	void __iomem *regs;
+	struct clk *clk;
+	struct dma_pool *desc_pool;
+	struct regmap *periph_regs;
+	spinlock_t lock;
+	unsigned int nr_threads;
+	unsigned int nr_channels;
+	unsigned int bus_width;
+	unsigned int max_burst_mult;
+	unsigned int max_xfer_size;
+	const struct mdc_dma_soc_data *soc;
+	struct mdc_chan channels[MDC_MAX_DMA_CHANNELS];
+};
+
+static inline u32 mdc_readl(struct mdc_dma *mdma, u32 reg)
+{
+	return readl(mdma->regs + reg);
+}
+
+static inline void mdc_writel(struct mdc_dma *mdma, u32 val, u32 reg)
+{
+	writel(val, mdma->regs + reg);
+}
+
+static inline u32 mdc_chan_readl(struct mdc_chan *mchan, u32 reg)
+{
+	return mdc_readl(mchan->mdma, mchan->chan_nr * 0x040 + reg);
+}
+
+static inline void mdc_chan_writel(struct mdc_chan *mchan, u32 val, u32 reg)
+{
+	mdc_writel(mchan->mdma, val, mchan->chan_nr * 0x040 + reg);
+}
+
+static inline struct mdc_chan *to_mdc_chan(struct dma_chan *c)
+{
+	return container_of(to_virt_chan(c), struct mdc_chan, vc);
+}
+
+static inline struct mdc_tx_desc *to_mdc_desc(struct dma_async_tx_descriptor *t)
+{
+	struct virt_dma_desc *vdesc = container_of(t, struct virt_dma_desc, tx);
+
+	return container_of(vdesc, struct mdc_tx_desc, vd);
+}
+
+static inline struct device *mdma2dev(struct mdc_dma *mdma)
+{
+	return mdma->dma_dev.dev;
+}
+
+static inline unsigned int to_mdc_width(unsigned int bytes)
+{
+	return ffs(bytes) - 1;
+}
+
+static inline void mdc_set_read_width(struct mdc_hw_list_desc *ldesc,
+				      unsigned int bytes)
+{
+	ldesc->gen_conf |= to_mdc_width(bytes) <<
+		MDC_GENERAL_CONFIG_WIDTH_R_SHIFT;
+}
+
+static inline void mdc_set_write_width(struct mdc_hw_list_desc *ldesc,
+				       unsigned int bytes)
+{
+	ldesc->gen_conf |= to_mdc_width(bytes) <<
+		MDC_GENERAL_CONFIG_WIDTH_W_SHIFT;
+}
+
+static void mdc_list_desc_config(struct mdc_chan *mchan,
+				 struct mdc_hw_list_desc *ldesc,
+				 enum dma_transfer_direction dir,
+				 dma_addr_t src, dma_addr_t dst, size_t len)
+{
+	struct mdc_dma *mdma = mchan->mdma;
+	unsigned int max_burst, burst_size;
+
+	ldesc->gen_conf = MDC_GENERAL_CONFIG_IEN | MDC_GENERAL_CONFIG_LIST_IEN |
+		MDC_GENERAL_CONFIG_LEVEL_INT | MDC_GENERAL_CONFIG_PHYSICAL_W |
+		MDC_GENERAL_CONFIG_PHYSICAL_R;
+	ldesc->readport_conf =
+		(mchan->thread << MDC_READ_PORT_CONFIG_STHREAD_SHIFT) |
+		(mchan->thread << MDC_READ_PORT_CONFIG_RTHREAD_SHIFT) |
+		(mchan->thread << MDC_READ_PORT_CONFIG_WTHREAD_SHIFT);
+	ldesc->read_addr = src;
+	ldesc->write_addr = dst;
+	ldesc->xfer_size = len - 1;
+	ldesc->node_addr = 0;
+	ldesc->cmds_done = 0;
+	ldesc->ctrl_status = MDC_CONTROL_AND_STATUS_LIST_EN |
+		MDC_CONTROL_AND_STATUS_EN;
+	ldesc->next_desc = NULL;
+
+	if (IS_ALIGNED(dst, mdma->bus_width) &&
+	    IS_ALIGNED(src, mdma->bus_width))
+		max_burst = mdma->bus_width * mdma->max_burst_mult;
+	else
+		max_burst = mdma->bus_width * (mdma->max_burst_mult - 1);
+
+	if (dir == DMA_MEM_TO_DEV) {
+		ldesc->gen_conf |= MDC_GENERAL_CONFIG_INC_R;
+		ldesc->readport_conf |= MDC_READ_PORT_CONFIG_DREQ_ENABLE;
+		mdc_set_read_width(ldesc, mdma->bus_width);
+		mdc_set_write_width(ldesc, mchan->config.dst_addr_width);
+		burst_size = min(max_burst, mchan->config.dst_maxburst *
+				 mchan->config.dst_addr_width);
+	} else if (dir == DMA_DEV_TO_MEM) {
+		ldesc->gen_conf |= MDC_GENERAL_CONFIG_INC_W;
+		ldesc->readport_conf |= MDC_READ_PORT_CONFIG_DREQ_ENABLE;
+		mdc_set_read_width(ldesc, mchan->config.src_addr_width);
+		mdc_set_write_width(ldesc, mdma->bus_width);
+		burst_size = min(max_burst, mchan->config.src_maxburst *
+				 mchan->config.src_addr_width);
+	} else {
+		ldesc->gen_conf |= MDC_GENERAL_CONFIG_INC_R |
+			MDC_GENERAL_CONFIG_INC_W;
+		mdc_set_read_width(ldesc, mdma->bus_width);
+		mdc_set_write_width(ldesc, mdma->bus_width);
+		burst_size = max_burst;
+	}
+	ldesc->readport_conf |= (burst_size - 1) <<
+		MDC_READ_PORT_CONFIG_BURST_SIZE_SHIFT;
+}
+
+static void mdc_list_desc_free(struct mdc_tx_desc *mdesc)
+{
+	struct mdc_dma *mdma = mdesc->chan->mdma;
+	struct mdc_hw_list_desc *curr, *next;
+	dma_addr_t curr_phys, next_phys;
+
+	curr = mdesc->list;
+	curr_phys = mdesc->list_phys;
+	while (curr) {
+		next = curr->next_desc;
+		next_phys = curr->node_addr;
+		dma_pool_free(mdma->desc_pool, curr, curr_phys);
+		curr = next;
+		curr_phys = next_phys;
+	}
+}
+
+static void mdc_desc_free(struct virt_dma_desc *vd)
+{
+	struct mdc_tx_desc *mdesc = to_mdc_desc(&vd->tx);
+
+	mdc_list_desc_free(mdesc);
+	kfree(mdesc);
+}
+
+static struct dma_async_tx_descriptor *mdc_prep_dma_memcpy(
+	struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, size_t len,
+	unsigned long flags)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	struct mdc_dma *mdma = mchan->mdma;
+	struct mdc_tx_desc *mdesc;
+	struct mdc_hw_list_desc *curr, *prev = NULL;
+	dma_addr_t curr_phys, prev_phys;
+
+	if (!len)
+		return NULL;
+
+	mdesc = kzalloc(sizeof(*mdesc), GFP_NOWAIT);
+	if (!mdesc)
+		return NULL;
+	mdesc->chan = mchan;
+	mdesc->list_xfer_size = len;
+
+	while (len > 0) {
+		size_t xfer_size;
+
+		curr = dma_pool_alloc(mdma->desc_pool, GFP_NOWAIT, &curr_phys);
+		if (!curr)
+			goto free_desc;
+
+		if (prev) {
+			prev->node_addr = curr_phys;
+			prev->next_desc = curr;
+		} else {
+			mdesc->list_phys = curr_phys;
+			mdesc->list = curr;
+		}
+
+		xfer_size = min_t(size_t, mdma->max_xfer_size, len);
+
+		mdc_list_desc_config(mchan, curr, DMA_MEM_TO_MEM, src, dest,
+				     xfer_size);
+
+		prev = curr;
+		prev_phys = curr_phys;
+
+		mdesc->list_len++;
+		src += xfer_size;
+		dest += xfer_size;
+		len -= xfer_size;
+	}
+
+	return vchan_tx_prep(&mchan->vc, &mdesc->vd, flags);
+
+free_desc:
+	mdc_desc_free(&mdesc->vd);
+
+	return NULL;
+}
+
+static int mdc_check_slave_width(struct mdc_chan *mchan,
+				 enum dma_transfer_direction dir)
+{
+	enum dma_slave_buswidth width;
+
+	if (dir == DMA_MEM_TO_DEV)
+		width = mchan->config.dst_addr_width;
+	else
+		width = mchan->config.src_addr_width;
+
+	switch (width) {
+	case DMA_SLAVE_BUSWIDTH_1_BYTE:
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+	case DMA_SLAVE_BUSWIDTH_8_BYTES:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (width > mchan->mdma->bus_width)
+		return -EINVAL;
+
+	return 0;
+}
+
+static struct dma_async_tx_descriptor *mdc_prep_dma_cyclic(
+	struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
+	size_t period_len, enum dma_transfer_direction dir,
+	unsigned long flags)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	struct mdc_dma *mdma = mchan->mdma;
+	struct mdc_tx_desc *mdesc;
+	struct mdc_hw_list_desc *curr, *prev = NULL;
+	dma_addr_t curr_phys, prev_phys;
+
+	if (!buf_len && !period_len)
+		return NULL;
+
+	if (!is_slave_direction(dir))
+		return NULL;
+
+	if (mdc_check_slave_width(mchan, dir) < 0)
+		return NULL;
+
+	mdesc = kzalloc(sizeof(*mdesc), GFP_NOWAIT);
+	if (!mdesc)
+		return NULL;
+	mdesc->chan = mchan;
+	mdesc->cyclic = true;
+	mdesc->list_xfer_size = buf_len;
+	mdesc->list_period_len = DIV_ROUND_UP(period_len,
+					      mdma->max_xfer_size);
+
+	while (buf_len > 0) {
+		size_t remainder = min(period_len, buf_len);
+
+		while (remainder > 0) {
+			size_t xfer_size;
+
+			curr = dma_pool_alloc(mdma->desc_pool, GFP_NOWAIT,
+					      &curr_phys);
+			if (!curr)
+				goto free_desc;
+
+			if (!prev) {
+				mdesc->list_phys = curr_phys;
+				mdesc->list = curr;
+			} else {
+				prev->node_addr = curr_phys;
+				prev->next_desc = curr;
+			}
+
+			xfer_size = min_t(size_t, mdma->max_xfer_size,
+					  remainder);
+
+			if (dir == DMA_MEM_TO_DEV) {
+				mdc_list_desc_config(mchan, curr, dir,
+						     buf_addr,
+						     mchan->config.dst_addr,
+						     xfer_size);
+			} else {
+				mdc_list_desc_config(mchan, curr, dir,
+						     mchan->config.src_addr,
+						     buf_addr,
+						     xfer_size);
+			}
+
+			prev = curr;
+			prev_phys = curr_phys;
+
+			mdesc->list_len++;
+			buf_addr += xfer_size;
+			buf_len -= xfer_size;
+			remainder -= xfer_size;
+		}
+	}
+	prev->node_addr = mdesc->list_phys;
+
+	return vchan_tx_prep(&mchan->vc, &mdesc->vd, flags);
+
+free_desc:
+	mdc_desc_free(&mdesc->vd);
+
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *mdc_prep_slave_sg(
+	struct dma_chan *chan, struct scatterlist *sgl,
+	unsigned int sg_len, enum dma_transfer_direction dir,
+	unsigned long flags, void *context)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	struct mdc_dma *mdma = mchan->mdma;
+	struct mdc_tx_desc *mdesc;
+	struct scatterlist *sg;
+	struct mdc_hw_list_desc *curr, *prev = NULL;
+	dma_addr_t curr_phys, prev_phys;
+	unsigned int i;
+
+	if (!sgl)
+		return NULL;
+
+	if (!is_slave_direction(dir))
+		return NULL;
+
+	if (mdc_check_slave_width(mchan, dir) < 0)
+		return NULL;
+
+	mdesc = kzalloc(sizeof(*mdesc), GFP_NOWAIT);
+	if (!mdesc)
+		return NULL;
+	mdesc->chan = mchan;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		dma_addr_t buf = sg_dma_address(sg);
+		size_t buf_len = sg_dma_len(sg);
+
+		while (buf_len > 0) {
+			size_t xfer_size;
+
+			curr = dma_pool_alloc(mdma->desc_pool, GFP_NOWAIT,
+					      &curr_phys);
+			if (!curr)
+				goto free_desc;
+
+			if (!prev) {
+				mdesc->list_phys = curr_phys;
+				mdesc->list = curr;
+			} else {
+				prev->node_addr = curr_phys;
+				prev->next_desc = curr;
+			}
+
+			xfer_size = min_t(size_t, mdma->max_xfer_size,
+					  buf_len);
+
+			if (dir == DMA_MEM_TO_DEV) {
+				mdc_list_desc_config(mchan, curr, dir, buf,
+						     mchan->config.dst_addr,
+						     xfer_size);
+			} else {
+				mdc_list_desc_config(mchan, curr, dir,
+						     mchan->config.src_addr,
+						     buf, xfer_size);
+			}
+
+			prev = curr;
+			prev_phys = curr_phys;
+
+			mdesc->list_len++;
+			mdesc->list_xfer_size += xfer_size;
+			buf += xfer_size;
+			buf_len -= xfer_size;
+		}
+	}
+
+	return vchan_tx_prep(&mchan->vc, &mdesc->vd, flags);
+
+free_desc:
+	mdc_desc_free(&mdesc->vd);
+
+	return NULL;
+}
+
+static void mdc_issue_desc(struct mdc_chan *mchan)
+{
+	struct mdc_dma *mdma = mchan->mdma;
+	struct virt_dma_desc *vd;
+	struct mdc_tx_desc *mdesc;
+	u32 val;
+
+	vd = vchan_next_desc(&mchan->vc);
+	if (!vd)
+		return;
+
+	list_del(&vd->node);
+
+	mdesc = to_mdc_desc(&vd->tx);
+	mchan->desc = mdesc;
+
+	dev_dbg(mdma2dev(mdma), "Issuing descriptor on channel %d\n",
+		mchan->chan_nr);
+
+	mdma->soc->enable_chan(mchan);
+
+	val = mdc_chan_readl(mchan, MDC_GENERAL_CONFIG);
+	val |= MDC_GENERAL_CONFIG_LIST_IEN | MDC_GENERAL_CONFIG_IEN |
+		MDC_GENERAL_CONFIG_LEVEL_INT | MDC_GENERAL_CONFIG_PHYSICAL_W |
+		MDC_GENERAL_CONFIG_PHYSICAL_R;
+	mdc_chan_writel(mchan, val, MDC_GENERAL_CONFIG);
+	val = (mchan->thread << MDC_READ_PORT_CONFIG_STHREAD_SHIFT) |
+		(mchan->thread << MDC_READ_PORT_CONFIG_RTHREAD_SHIFT) |
+		(mchan->thread << MDC_READ_PORT_CONFIG_WTHREAD_SHIFT);
+	mdc_chan_writel(mchan, val, MDC_READ_PORT_CONFIG);
+	mdc_chan_writel(mchan, mdesc->list_phys, MDC_LIST_NODE_ADDRESS);
+	val = mdc_chan_readl(mchan, MDC_CONTROL_AND_STATUS);
+	val |= MDC_CONTROL_AND_STATUS_LIST_EN;
+	mdc_chan_writel(mchan, val, MDC_CONTROL_AND_STATUS);
+}
+
+static void mdc_issue_pending(struct dma_chan *chan)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&mchan->vc.lock, flags);
+	if (vchan_issue_pending(&mchan->vc) && !mchan->desc)
+		mdc_issue_desc(mchan);
+	spin_unlock_irqrestore(&mchan->vc.lock, flags);
+}
+
+static enum dma_status mdc_tx_status(struct dma_chan *chan,
+	dma_cookie_t cookie, struct dma_tx_state *txstate)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	struct mdc_tx_desc *mdesc;
+	struct virt_dma_desc *vd;
+	unsigned long flags;
+	size_t bytes = 0;
+	int ret;
+
+	ret = dma_cookie_status(chan, cookie, txstate);
+	if (ret == DMA_COMPLETE)
+		return ret;
+
+	if (!txstate)
+		return ret;
+
+	spin_lock_irqsave(&mchan->vc.lock, flags);
+	vd = vchan_find_desc(&mchan->vc, cookie);
+	if (vd) {
+		mdesc = to_mdc_desc(&vd->tx);
+		bytes = mdesc->list_xfer_size;
+	} else if (mchan->desc && mchan->desc->vd.tx.cookie == cookie) {
+		struct mdc_hw_list_desc *ldesc;
+		u32 val1, val2, done, processed, residue;
+		int i, cmds;
+
+		mdesc = mchan->desc;
+
+		/*
+		 * Determine the number of commands that haven't been
+		 * processed (handled by the IRQ handler) yet.
+		 */
+		do {
+			val1 = mdc_chan_readl(mchan, MDC_CMDS_PROCESSED) &
+				~MDC_CMDS_PROCESSED_INT_ACTIVE;
+			residue = mdc_chan_readl(mchan,
+						 MDC_ACTIVE_TRANSFER_SIZE);
+			val2 = mdc_chan_readl(mchan, MDC_CMDS_PROCESSED) &
+				~MDC_CMDS_PROCESSED_INT_ACTIVE;
+		} while (val1 != val2);
+
+		done = (val1 >> MDC_CMDS_PROCESSED_CMDS_DONE_SHIFT) &
+			MDC_CMDS_PROCESSED_CMDS_DONE_MASK;
+		processed = (val1 >> MDC_CMDS_PROCESSED_CMDS_PROCESSED_SHIFT) &
+			MDC_CMDS_PROCESSED_CMDS_PROCESSED_MASK;
+		cmds = (done - processed) %
+			(MDC_CMDS_PROCESSED_CMDS_DONE_MASK + 1);
+
+		/*
+		 * If the command loaded event hasn't been processed yet, then
+		 * the difference above includes an extra command.
+		 */
+		if (!mdesc->cmd_loaded)
+			cmds--;
+		else
+			cmds += mdesc->list_cmds_done;
+
+		bytes = mdesc->list_xfer_size;
+		ldesc = mdesc->list;
+		for (i = 0; i < cmds; i++) {
+			bytes -= ldesc->xfer_size + 1;
+			ldesc = ldesc->next_desc;
+		}
+		if (ldesc) {
+			if (residue != MDC_TRANSFER_SIZE_MASK)
+				bytes -= ldesc->xfer_size - residue;
+			else
+				bytes -= ldesc->xfer_size + 1;
+		}
+	}
+	spin_unlock_irqrestore(&mchan->vc.lock, flags);
+
+	dma_set_residue(txstate, bytes);
+
+	return ret;
+}
+
+static int mdc_terminate_all(struct dma_chan *chan)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	struct mdc_tx_desc *mdesc;
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&mchan->vc.lock, flags);
+
+	mdc_chan_writel(mchan, MDC_CONTROL_AND_STATUS_CANCEL,
+			MDC_CONTROL_AND_STATUS);
+
+	mdesc = mchan->desc;
+	mchan->desc = NULL;
+	vchan_get_all_descriptors(&mchan->vc, &head);
+
+	spin_unlock_irqrestore(&mchan->vc.lock, flags);
+
+	if (mdesc)
+		mdc_desc_free(&mdesc->vd);
+	vchan_dma_desc_free_list(&mchan->vc, &head);
+
+	return 0;
+}
+
+static int mdc_slave_config(struct dma_chan *chan,
+			    struct dma_slave_config *config)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&mchan->vc.lock, flags);
+	mchan->config = *config;
+	spin_unlock_irqrestore(&mchan->vc.lock, flags);
+
+	return 0;
+}
+
+static int mdc_alloc_chan_resources(struct dma_chan *chan)
+{
+	return 0;
+}
+
+static void mdc_free_chan_resources(struct dma_chan *chan)
+{
+	struct mdc_chan *mchan = to_mdc_chan(chan);
+	struct mdc_dma *mdma = mchan->mdma;
+
+	mdc_terminate_all(chan);
+
+	mdma->soc->disable_chan(mchan);
+}
+
+static irqreturn_t mdc_chan_irq(int irq, void *dev_id)
+{
+	struct mdc_chan *mchan = (struct mdc_chan *)dev_id;
+	struct mdc_tx_desc *mdesc;
+	u32 val, processed, done1, done2;
+	unsigned int i;
+
+	spin_lock(&mchan->vc.lock);
+
+	val = mdc_chan_readl(mchan, MDC_CMDS_PROCESSED);
+	processed = (val >> MDC_CMDS_PROCESSED_CMDS_PROCESSED_SHIFT) &
+		MDC_CMDS_PROCESSED_CMDS_PROCESSED_MASK;
+	/*
+	 * CMDS_DONE may have incremented between reading CMDS_PROCESSED
+	 * and clearing INT_ACTIVE.  Re-read CMDS_PROCESSED to ensure we
+	 * didn't miss a command completion.
+	 */
+	do {
+		val = mdc_chan_readl(mchan, MDC_CMDS_PROCESSED);
+		done1 = (val >> MDC_CMDS_PROCESSED_CMDS_DONE_SHIFT) &
+			MDC_CMDS_PROCESSED_CMDS_DONE_MASK;
+		val &= ~((MDC_CMDS_PROCESSED_CMDS_PROCESSED_MASK <<
+			  MDC_CMDS_PROCESSED_CMDS_PROCESSED_SHIFT) |
+			 MDC_CMDS_PROCESSED_INT_ACTIVE);
+		val |= done1 << MDC_CMDS_PROCESSED_CMDS_PROCESSED_SHIFT;
+		mdc_chan_writel(mchan, val, MDC_CMDS_PROCESSED);
+		val = mdc_chan_readl(mchan, MDC_CMDS_PROCESSED);
+		done2 = (val >> MDC_CMDS_PROCESSED_CMDS_DONE_SHIFT) &
+			MDC_CMDS_PROCESSED_CMDS_DONE_MASK;
+	} while (done1 != done2);
+
+	dev_dbg(mdma2dev(mchan->mdma), "IRQ on channel %d\n", mchan->chan_nr);
+
+	mdesc = mchan->desc;
+	if (!mdesc) {
+		dev_warn(mdma2dev(mchan->mdma),
+			 "IRQ with no active descriptor on channel %d\n",
+			 mchan->chan_nr);
+		goto out;
+	}
+
+	for (i = processed; i != done1;
+	     i = (i + 1) % (MDC_CMDS_PROCESSED_CMDS_PROCESSED_MASK + 1)) {
+		/*
+		 * The first interrupt in a transfer indicates that the
+		 * command list has been loaded, not that a command has
+		 * been completed.
+		 */
+		if (!mdesc->cmd_loaded) {
+			mdesc->cmd_loaded = true;
+			continue;
+		}
+
+		mdesc->list_cmds_done++;
+		if (mdesc->cyclic) {
+			mdesc->list_cmds_done %= mdesc->list_len;
+			if (mdesc->list_cmds_done % mdesc->list_period_len == 0)
+				vchan_cyclic_callback(&mdesc->vd);
+		} else if (mdesc->list_cmds_done == mdesc->list_len) {
+			mchan->desc = NULL;
+			vchan_cookie_complete(&mdesc->vd);
+			mdc_issue_desc(mchan);
+			break;
+		}
+	}
+out:
+	spin_unlock(&mchan->vc.lock);
+
+	return IRQ_HANDLED;
+}
+
+static struct dma_chan *mdc_of_xlate(struct of_phandle_args *dma_spec,
+				     struct of_dma *ofdma)
+{
+	struct mdc_dma *mdma = ofdma->of_dma_data;
+	struct dma_chan *chan;
+
+	if (dma_spec->args_count != 3)
+		return NULL;
+
+	list_for_each_entry(chan, &mdma->dma_dev.channels, device_node) {
+		struct mdc_chan *mchan = to_mdc_chan(chan);
+
+		if (!(dma_spec->args[1] & BIT(mchan->chan_nr)))
+			continue;
+		if (dma_get_slave_channel(chan)) {
+			mchan->periph = dma_spec->args[0];
+			mchan->thread = dma_spec->args[2];
+			return chan;
+		}
+	}
+
+	return NULL;
+}
+
+#define PISTACHIO_CR_PERIPH_DMA_ROUTE(ch)	(0x120 + 0x4 * ((ch) / 4))
+#define PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(ch) (8 * ((ch) % 4))
+#define PISTACHIO_CR_PERIPH_DMA_ROUTE_MASK	0x3f
+
+static void pistachio_mdc_enable_chan(struct mdc_chan *mchan)
+{
+	struct mdc_dma *mdma = mchan->mdma;
+
+	regmap_update_bits(mdma->periph_regs,
+			   PISTACHIO_CR_PERIPH_DMA_ROUTE(mchan->chan_nr),
+			   PISTACHIO_CR_PERIPH_DMA_ROUTE_MASK <<
+			   PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(mchan->chan_nr),
+			   mchan->periph <<
+			   PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(mchan->chan_nr));
+}
+
+static void pistachio_mdc_disable_chan(struct mdc_chan *mchan)
+{
+	struct mdc_dma *mdma = mchan->mdma;
+
+	regmap_update_bits(mdma->periph_regs,
+			   PISTACHIO_CR_PERIPH_DMA_ROUTE(mchan->chan_nr),
+			   PISTACHIO_CR_PERIPH_DMA_ROUTE_MASK <<
+			   PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(mchan->chan_nr),
+			   0);
+}
+
+static const struct mdc_dma_soc_data pistachio_mdc_data = {
+	.enable_chan = pistachio_mdc_enable_chan,
+	.disable_chan = pistachio_mdc_disable_chan,
+};
+
+static const struct of_device_id mdc_dma_of_match[] = {
+	{ .compatible = "img,pistachio-mdc-dma", .data = &pistachio_mdc_data, },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, mdc_dma_of_match);
+
+static int mdc_dma_probe(struct platform_device *pdev)
+{
+	struct mdc_dma *mdma;
+	struct resource *res;
+	const struct of_device_id *match;
+	unsigned int i;
+	u32 val;
+	int ret;
+
+	mdma = devm_kzalloc(&pdev->dev, sizeof(*mdma), GFP_KERNEL);
+	if (!mdma)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, mdma);
+
+	match = of_match_device(mdc_dma_of_match, &pdev->dev);
+	mdma->soc = match->data;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mdma->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(mdma->regs))
+		return PTR_ERR(mdma->regs);
+
+	mdma->periph_regs = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+							    "img,cr-periph");
+	if (IS_ERR(mdma->periph_regs))
+		return PTR_ERR(mdma->periph_regs);
+
+	mdma->clk = devm_clk_get(&pdev->dev, "sys");
+	if (IS_ERR(mdma->clk))
+		return PTR_ERR(mdma->clk);
+
+	ret = clk_prepare_enable(mdma->clk);
+	if (ret)
+		return ret;
+
+	dma_cap_zero(mdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_SLAVE, mdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_PRIVATE, mdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_CYCLIC, mdma->dma_dev.cap_mask);
+	dma_cap_set(DMA_MEMCPY, mdma->dma_dev.cap_mask);
+
+	val = mdc_readl(mdma, MDC_GLOBAL_CONFIG_A);
+	mdma->nr_channels = (val >> MDC_GLOBAL_CONFIG_A_DMA_CONTEXTS_SHIFT) &
+		MDC_GLOBAL_CONFIG_A_DMA_CONTEXTS_MASK;
+	mdma->nr_threads =
+		1 << ((val >> MDC_GLOBAL_CONFIG_A_THREAD_ID_WIDTH_SHIFT) &
+		      MDC_GLOBAL_CONFIG_A_THREAD_ID_WIDTH_MASK);
+	mdma->bus_width =
+		(1 << ((val >> MDC_GLOBAL_CONFIG_A_SYS_DAT_WIDTH_SHIFT) &
+		       MDC_GLOBAL_CONFIG_A_SYS_DAT_WIDTH_MASK)) / 8;
+	/*
+	 * Although transfer sizes of up to MDC_TRANSFER_SIZE_MASK + 1 bytes
+	 * are supported, this makes it possible for the value reported in
+	 * MDC_ACTIVE_TRANSFER_SIZE to be ambiguous - an active transfer size
+	 * of MDC_TRANSFER_SIZE_MASK may indicate either that 0 bytes or
+	 * MDC_TRANSFER_SIZE_MASK + 1 bytes are remaining.  To eliminate this
+	 * ambiguity, restrict transfer sizes to one bus-width less than the
+	 * actual maximum.
+	 */
+	mdma->max_xfer_size = MDC_TRANSFER_SIZE_MASK + 1 - mdma->bus_width;
+
+	of_property_read_u32(pdev->dev.of_node, "dma-channels",
+			     &mdma->nr_channels);
+	ret = of_property_read_u32(pdev->dev.of_node,
+				   "img,max-burst-multiplier",
+				   &mdma->max_burst_mult);
+	if (ret)
+		goto disable_clk;
+
+	mdma->dma_dev.dev = &pdev->dev;
+	mdma->dma_dev.device_prep_slave_sg = mdc_prep_slave_sg;
+	mdma->dma_dev.device_prep_dma_cyclic = mdc_prep_dma_cyclic;
+	mdma->dma_dev.device_prep_dma_memcpy = mdc_prep_dma_memcpy;
+	mdma->dma_dev.device_alloc_chan_resources = mdc_alloc_chan_resources;
+	mdma->dma_dev.device_free_chan_resources = mdc_free_chan_resources;
+	mdma->dma_dev.device_tx_status = mdc_tx_status;
+	mdma->dma_dev.device_issue_pending = mdc_issue_pending;
+	mdma->dma_dev.device_terminate_all = mdc_terminate_all;
+	mdma->dma_dev.device_config = mdc_slave_config;
+
+	mdma->dma_dev.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	mdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+	for (i = 1; i <= mdma->bus_width; i <<= 1) {
+		mdma->dma_dev.src_addr_widths |= BIT(i);
+		mdma->dma_dev.dst_addr_widths |= BIT(i);
+	}
+
+	INIT_LIST_HEAD(&mdma->dma_dev.channels);
+	for (i = 0; i < mdma->nr_channels; i++) {
+		struct mdc_chan *mchan = &mdma->channels[i];
+
+		mchan->mdma = mdma;
+		mchan->chan_nr = i;
+		mchan->irq = platform_get_irq(pdev, i);
+		if (mchan->irq < 0) {
+			ret = mchan->irq;
+			goto disable_clk;
+		}
+		ret = devm_request_irq(&pdev->dev, mchan->irq, mdc_chan_irq,
+				       IRQ_TYPE_LEVEL_HIGH,
+				       dev_name(&pdev->dev), mchan);
+		if (ret < 0)
+			goto disable_clk;
+
+		mchan->vc.desc_free = mdc_desc_free;
+		vchan_init(&mchan->vc, &mdma->dma_dev);
+	}
+
+	mdma->desc_pool = dmam_pool_create(dev_name(&pdev->dev), &pdev->dev,
+					   sizeof(struct mdc_hw_list_desc),
+					   4, 0);
+	if (!mdma->desc_pool) {
+		ret = -ENOMEM;
+		goto disable_clk;
+	}
+
+	ret = dma_async_device_register(&mdma->dma_dev);
+	if (ret)
+		goto disable_clk;
+
+	ret = of_dma_controller_register(pdev->dev.of_node, mdc_of_xlate, mdma);
+	if (ret)
+		goto unregister;
+
+	dev_info(&pdev->dev, "MDC with %u channels and %u threads\n",
+		 mdma->nr_channels, mdma->nr_threads);
+
+	return 0;
+
+unregister:
+	dma_async_device_unregister(&mdma->dma_dev);
+disable_clk:
+	clk_disable_unprepare(mdma->clk);
+	return ret;
+}
+
+static int mdc_dma_remove(struct platform_device *pdev)
+{
+	struct mdc_dma *mdma = platform_get_drvdata(pdev);
+	struct mdc_chan *mchan, *next;
+
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&mdma->dma_dev);
+
+	list_for_each_entry_safe(mchan, next, &mdma->dma_dev.channels,
+				 vc.chan.device_node) {
+		list_del(&mchan->vc.chan.device_node);
+
+		synchronize_irq(mchan->irq);
+		devm_free_irq(&pdev->dev, mchan->irq, mchan);
+
+		tasklet_kill(&mchan->vc.task);
+	}
+
+	clk_disable_unprepare(mdma->clk);
+
+	return 0;
+}
+
+static struct platform_driver mdc_dma_driver = {
+	.driver = {
+		.name = "img-mdc-dma",
+		.of_match_table = of_match_ptr(mdc_dma_of_match),
+	},
+	.probe = mdc_dma_probe,
+	.remove = mdc_dma_remove,
+};
+module_platform_driver(mdc_dma_driver);
+
+MODULE_DESCRIPTION("IMG Multi-threaded DMA Controller (MDC) driver");
+MODULE_AUTHOR("Andrew Bresticker <abrestic@chromium.org>");
+MODULE_LICENSE("GPL v2");