[PATCH v3 3/4] dmaengine: Add Actions Semi Owl family S900 DMA driver

[Manivannan Sadhasivam]

Add Actions Semi Owl family S900 DMA driver.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
 drivers/dma/Kconfig   |   8 +
 drivers/dma/Makefile  |   1 +
 drivers/dma/owl-dma.c | 971 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 980 insertions(+)
 create mode 100644 drivers/dma/owl-dma.c

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index ca1680afa20a..92a278e6618c 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -413,6 +413,14 @@ config NBPFAXI_DMA
 	help
 	  Support for "Type-AXI" NBPF DMA IPs from Renesas
 
+config OWL_DMA
+	tristate "Actions Semi Owl SoCs DMA support"
+	depends on ARCH_ACTIONS
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the Actions Semi Owl SoCs DMA controller.
+
 config PCH_DMA
 	tristate "Intel EG20T PCH / LAPIS Semicon IOH(ML7213/ML7223/ML7831) DMA"
 	depends on PCI && (X86_32 || COMPILE_TEST)
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index 203a99d68315..c91702d88b95 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_MV_XOR_V2) += mv_xor_v2.o
 obj-$(CONFIG_MXS_DMA) += mxs-dma.o
 obj-$(CONFIG_MX3_IPU) += ipu/
 obj-$(CONFIG_NBPFAXI_DMA) += nbpfaxi.o
+obj-$(CONFIG_OWL_DMA) += owl-dma.o
 obj-$(CONFIG_PCH_DMA) += pch_dma.o
 obj-$(CONFIG_PL330_DMA) += pl330.o
 obj-$(CONFIG_PPC_BESTCOMM) += bestcomm/
diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
new file mode 100644
index 000000000000..7812a6338acd
--- /dev/null
+++ b/drivers/dma/owl-dma.c
@@ -0,0 +1,971 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Actions Semi Owl SoCs DMA driver
+//
+// Copyright (c) 2014 Actions Semi Inc.
+// Author: David Liu <liuwei@xxxxxxxxxxxxxxxx>
+//
+// Copyright (c) 2018 Linaro Ltd.
+// Author: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/slab.h>
+#include "virt-dma.h"
+
+#define OWL_DMA_FRAME_MAX_LENGTH		0xfffff
+
+/* Global DMA Controller Registers */
+#define OWL_DMA_IRQ_PD0				0x00
+#define OWL_DMA_IRQ_PD1				0x04
+#define OWL_DMA_IRQ_PD2				0x08
+#define OWL_DMA_IRQ_PD3				0x0C
+#define OWL_DMA_IRQ_EN0				0x10
+#define OWL_DMA_IRQ_EN1				0x14
+#define OWL_DMA_IRQ_EN2				0x18
+#define OWL_DMA_IRQ_EN3				0x1C
+#define OWL_DMA_SECURE_ACCESS_CTL		0x20
+#define OWL_DMA_NIC_QOS				0x24
+#define OWL_DMA_DBGSEL				0x28
+#define OWL_DMA_IDLE_STAT			0x2C
+
+/* Channel Registers */
+#define OWL_DMA_CHAN_BASE(i)			(0x100 + (i) * 0x100)
+#define OWL_DMAX_MODE				0x00
+#define OWL_DMAX_SOURCE				0x04
+#define OWL_DMAX_DESTINATION			0x08
+#define OWL_DMAX_FRAME_LEN			0x0C
+#define OWL_DMAX_FRAME_CNT			0x10
+#define OWL_DMAX_REMAIN_FRAME_CNT		0x14
+#define OWL_DMAX_REMAIN_CNT			0x18
+#define OWL_DMAX_SOURCE_STRIDE			0x1C
+#define OWL_DMAX_DESTINATION_STRIDE		0x20
+#define OWL_DMAX_START				0x24
+#define OWL_DMAX_PAUSE				0x28
+#define OWL_DMAX_CHAINED_CTL			0x2C
+#define OWL_DMAX_CONSTANT			0x30
+#define OWL_DMAX_LINKLIST_CTL			0x34
+#define OWL_DMAX_NEXT_DESCRIPTOR		0x38
+#define OWL_DMAX_CURRENT_DESCRIPTOR_NUM		0x3C
+#define OWL_DMAX_INT_CTL			0x40
+#define OWL_DMAX_INT_STATUS			0x44
+#define OWL_DMAX_CURRENT_SOURCE_POINTER		0x48
+#define OWL_DMAX_CURRENT_DESTINATION_POINTER	0x4C
+
+/* OWL_DMAX_MODE Bits */
+#define OWL_DMA_MODE_TS(x)			(((x) & GENMASK(5, 0)) << 0)
+#define OWL_DMA_MODE_ST(x)			(((x) & GENMASK(1, 0)) << 8)
+#define	OWL_DMA_MODE_ST_DEV			OWL_DMA_MODE_ST(0)
+#define	OWL_DMA_MODE_ST_DCU			OWL_DMA_MODE_ST(2)
+#define	OWL_DMA_MODE_ST_SRAM			OWL_DMA_MODE_ST(3)
+#define OWL_DMA_MODE_DT(x)			(((x) & GENMASK(1, 0)) << 10)
+#define	OWL_DMA_MODE_DT_DEV			OWL_DMA_MODE_DT(0)
+#define	OWL_DMA_MODE_DT_DCU			OWL_DMA_MODE_DT(2)
+#define	OWL_DMA_MODE_DT_SRAM			OWL_DMA_MODE_DT(3)
+#define OWL_DMA_MODE_SAM(x)			(((x) & GENMASK(1, 0)) << 16)
+#define	OWL_DMA_MODE_SAM_CONST			OWL_DMA_MODE_SAM(0)
+#define	OWL_DMA_MODE_SAM_INC			OWL_DMA_MODE_SAM(1)
+#define	OWL_DMA_MODE_SAM_STRIDE			OWL_DMA_MODE_SAM(2)
+#define OWL_DMA_MODE_DAM(x)			(((x) & GENMASK(1, 0)) << 18)
+#define	OWL_DMA_MODE_DAM_CONST			OWL_DMA_MODE_DAM(0)
+#define	OWL_DMA_MODE_DAM_INC			OWL_DMA_MODE_DAM(1)
+#define	OWL_DMA_MODE_DAM_STRIDE			OWL_DMA_MODE_DAM(2)
+#define OWL_DMA_MODE_PW(x)			(((x) & GENMASK(2, 0)) << 20)
+#define OWL_DMA_MODE_CB				BIT(23)
+#define OWL_DMA_MODE_NDDBW(x)			(((x) & 0x1) << 28)
+#define	OWL_DMA_MODE_NDDBW_32BIT		OWL_DMA_MODE_NDDBW(0)
+#define	OWL_DMA_MODE_NDDBW_8BIT			OWL_DMA_MODE_NDDBW(1)
+#define OWL_DMA_MODE_CFE			BIT(29)
+#define OWL_DMA_MODE_LME			BIT(30)
+#define OWL_DMA_MODE_CME			BIT(31)
+
+/* OWL_DMAX_LINKLIST_CTL Bits */
+#define OWL_DMA_LLC_SAV(x)			(((x) & GENMASK(1, 0)) << 8)
+#define	OWL_DMA_LLC_SAV_INC			OWL_DMA_LLC_SAV(0)
+#define	OWL_DMA_LLC_SAV_LOAD_NEXT		OWL_DMA_LLC_SAV(1)
+#define	OWL_DMA_LLC_SAV_LOAD_PREV		OWL_DMA_LLC_SAV(2)
+#define OWL_DMA_LLC_DAV(x)			(((x) & GENMASK(1, 0)) << 10)
+#define	OWL_DMA_LLC_DAV_INC			OWL_DMA_LLC_DAV(0)
+#define	OWL_DMA_LLC_DAV_LOAD_NEXT		OWL_DMA_LLC_DAV(1)
+#define	OWL_DMA_LLC_DAV_LOAD_PREV		OWL_DMA_LLC_DAV(2)
+#define OWL_DMA_LLC_SUSPEND			BIT(16)
+
+/* OWL_DMAX_INT_CTL Bits */
+#define OWL_DMA_INTCTL_BLOCK			BIT(0)
+#define OWL_DMA_INTCTL_SUPER_BLOCK		BIT(1)
+#define OWL_DMA_INTCTL_FRAME			BIT(2)
+#define OWL_DMA_INTCTL_HALF_FRAME		BIT(3)
+#define OWL_DMA_INTCTL_LAST_FRAME		BIT(4)
+
+/* OWL_DMAX_INT_STATUS Bits */
+#define OWL_DMA_INTSTAT_BLOCK			BIT(0)
+#define OWL_DMA_INTSTAT_SUPER_BLOCK		BIT(1)
+#define OWL_DMA_INTSTAT_FRAME			BIT(2)
+#define OWL_DMA_INTSTAT_HALF_FRAME		BIT(3)
+#define OWL_DMA_INTSTAT_LAST_FRAME		BIT(4)
+
+/* Pack shift and newshift in a single word */
+#define BIT_FIELD(val, width, shift, newshift)	\
+		((((val) >> (shift)) & ((BIT(width)) - 1)) << (newshift))
+
+/**
+ * struct owl_dma_lli_hw - Hardware link list for dma transfer
+ * @next_lli: physical address of the next link list
+ * @saddr: source physical address
+ * @daddr: destination physical address
+ * @flen: frame length
+ * @fcnt: frame count
+ * @src_stride: source stride
+ * @dst_stride: destination stride
+ * @ctrla: dma_mode and linklist ctrl config
+ * @ctrlb: interrupt config
+ * @const_num: data for constant fill
+ */
+struct owl_dma_lli_hw {
+	u32	next_lli;
+	u32	saddr;
+	u32	daddr;
+	u32	flen:20;
+	u32	fcnt:12;
+	u32	src_stride;
+	u32	dst_stride;
+	u32	ctrla;
+	u32	ctrlb;
+	u32	const_num;
+};
+
+/**
+ * struct owl_dma_lli - Link list for dma transfer
+ * @hw: hardware link list
+ * @phys: physical address of hardware link list
+ * @node: node for txd's lli_list
+ */
+struct owl_dma_lli {
+	struct  owl_dma_lli_hw	hw;
+	dma_addr_t		phys;
+	struct list_head	node;
+};
+
+/**
+ * struct owl_dma_txd - Wrapper for struct dma_async_tx_descriptor
+ * @vd: virtual DMA descriptor
+ * @lli_list: link list of lli nodes
+ */
+struct owl_dma_txd {
+	struct virt_dma_desc	vd;
+	struct list_head	lli_list;
+};
+
+/**
+ * struct owl_dma_pchan - Holder for the physical channels
+ * @id: physical index to this channel
+ * @base: virtual memory base for the dma channel
+ * @vchan: the virtual channel currently being served by this physical channel
+ * @lock: a lock to use when altering an instance of this struct
+ */
+struct owl_dma_pchan {
+	u32			id;
+	void __iomem		*base;
+	struct owl_dma_vchan	*vchan;
+	spinlock_t		lock;
+};
+
+/**
+ * struct owl_dma_pchan - Wrapper for DMA ENGINE channel
+ * @vc: wrappped virtual channel
+ * @pchan: the physical channel utilized by this channel
+ * @txd: active transaction on this channel
+ */
+struct owl_dma_vchan {
+	struct virt_dma_chan	vc;
+	struct owl_dma_pchan	*pchan;
+	struct owl_dma_txd	*txd;
+};
+
+/**
+ * struct owl_dma - Holder for the Owl DMA controller
+ * @dma: dma engine for this instance
+ * @base: virtual memory base for the DMA controller
+ * @clk: clock for the DMA controller
+ * @lock: a lock to use when change DMA controller global register
+ * @lli_pool: a pool for the LLI descriptors
+ * @nr_pchans: the number of physical channels
+ * @pchans: array of data for the physical channels
+ * @nr_vchans: the number of physical channels
+ * @vchans: array of data for the physical channels
+ */
+struct owl_dma {
+	struct dma_device	dma;
+	void __iomem		*base;
+	struct clk		*clk;
+	spinlock_t		lock;
+	struct dma_pool		*lli_pool;
+	int			irq;
+
+	unsigned int		nr_pchans;
+	struct owl_dma_pchan	*pchans;
+
+	unsigned int		nr_vchans;
+	struct owl_dma_vchan	*vchans;
+};
+
+static void pchan_update(struct owl_dma_pchan *pchan, u32 reg,
+			 u32 val, bool state)
+{
+	u32 regval;
+
+	regval = readl(pchan->base + reg);
+
+	if (state)
+		regval |= val;
+	else
+		regval &= ~val;
+
+	writel(val, pchan->base + reg);
+}
+
+static void pchan_writel(struct owl_dma_pchan *pchan, u32 reg, u32 data)
+{
+	writel(data, pchan->base + reg);
+}
+
+static u32 pchan_readl(struct owl_dma_pchan *pchan, u32 reg)
+{
+	return readl(pchan->base + reg);
+}
+
+static void dma_update(struct owl_dma *od, u32 reg, u32 val, bool state)
+{
+	u32 regval;
+
+	regval = readl(od->base + reg);
+
+	if (state)
+		regval |= val;
+	else
+		regval &= ~val;
+
+	writel(val, od->base + reg);
+}
+
+static void dma_writel(struct owl_dma *od, u32 reg, u32 data)
+{
+	writel(data, od->base + reg);
+}
+
+static u32 dma_readl(struct owl_dma *od, u32 reg)
+{
+	return readl(od->base + reg);
+}
+
+static inline struct owl_dma *to_owl_dma(struct dma_device *dd)
+{
+	return container_of(dd, struct owl_dma, dma);
+}
+
+static struct device *chan2dev(struct dma_chan *chan)
+{
+	return &chan->dev->device;
+}
+
+static inline struct owl_dma_vchan *to_owl_vchan(struct dma_chan *chan)
+{
+	return container_of(chan, struct owl_dma_vchan, vc.chan);
+}
+
+static inline struct owl_dma_txd *to_owl_txd(struct dma_async_tx_descriptor *tx)
+{
+	return container_of(tx, struct owl_dma_txd, vd.tx);
+}
+
+static inline u32 llc_hw_ctrla(u32 mode, u32 llc_ctl)
+{
+	u32 ctl;
+
+	ctl = BIT_FIELD(mode, 4, 28, 28) |
+	      BIT_FIELD(mode, 8, 16, 20) |
+	      BIT_FIELD(mode, 4, 8, 16) |
+	      BIT_FIELD(mode, 6, 0, 10) |
+	      BIT_FIELD(llc_ctl, 2, 10, 8) |
+	      BIT_FIELD(llc_ctl, 2, 8, 6);
+
+	return ctl;
+}
+
+static inline u32 llc_hw_ctrlb(u32 int_ctl)
+{
+	u32 ctl;
+
+	ctl = BIT_FIELD(int_ctl, 7, 0, 18);
+
+	return ctl;
+}
+
+static void owl_dma_free_lli(struct owl_dma *od,
+			     struct owl_dma_lli *lli)
+{
+	list_del(&lli->node);
+	dma_pool_free(od->lli_pool, lli, lli->phys);
+}
+
+static struct owl_dma_lli *owl_dma_alloc_lli(struct owl_dma *od)
+{
+	struct owl_dma_lli *lli;
+	dma_addr_t phys;
+
+	lli = dma_pool_alloc(od->lli_pool, GFP_NOWAIT, &phys);
+	if (!lli)
+		return NULL;
+
+	INIT_LIST_HEAD(&lli->node);
+	lli->phys = phys;
+
+	return lli;
+}
+
+static struct owl_dma_lli *owl_dma_add_lli(struct owl_dma_txd *txd,
+					   struct owl_dma_lli *prev,
+					   struct owl_dma_lli *next)
+{
+	list_add_tail(&next->node, &txd->lli_list);
+
+	if (prev) {
+		prev->hw.next_lli = next->phys;
+		prev->hw.ctrla |= llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
+	}
+
+	return next;
+}
+
+static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
+				  struct owl_dma_lli *lli,
+				  dma_addr_t src, dma_addr_t dst,
+				  u32 len, enum dma_transfer_direction dir)
+{
+	struct owl_dma_lli_hw *hw = &lli->hw;
+	u32 mode;
+
+	mode = OWL_DMA_MODE_PW(0);
+
+	switch (dir) {
+	case DMA_MEM_TO_MEM:
+		mode |= OWL_DMA_MODE_TS(0) | OWL_DMA_MODE_ST_DCU |
+			OWL_DMA_MODE_DT_DCU | OWL_DMA_MODE_SAM_INC |
+			OWL_DMA_MODE_DAM_INC;
+
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	hw->next_lli = 0; /* One link list by default */
+	hw->saddr = src;
+	hw->daddr = dst;
+
+	hw->fcnt = 1; /* Frame count fixed as 1 */
+	hw->flen = len; /* Max frame length is 1MB */
+	hw->src_stride = 0;
+	hw->dst_stride = 0;
+	hw->ctrla = llc_hw_ctrla(mode,
+				 OWL_DMA_LLC_SAV_LOAD_NEXT |
+				 OWL_DMA_LLC_DAV_LOAD_NEXT);
+
+	hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
+
+	return 0;
+}
+
+static struct owl_dma_pchan *owl_dma_get_pchan(struct owl_dma *od,
+					       struct owl_dma_vchan *vchan)
+{
+	struct owl_dma_pchan *pchan = NULL;
+	unsigned long flags;
+	int i;
+
+	for (i = 0; i < od->nr_pchans; i++) {
+		pchan = &od->pchans[i];
+
+		spin_lock_irqsave(&pchan->lock, flags);
+		if (!pchan->vchan) {
+			pchan->vchan = vchan;
+			spin_unlock_irqrestore(&pchan->lock, flags);
+			break;
+		}
+
+		spin_unlock_irqrestore(&pchan->lock, flags);
+	}
+
+	return pchan;
+}
+
+static int owl_dma_pchan_busy(struct owl_dma *od, struct owl_dma_pchan *pchan)
+{
+	unsigned int val;
+
+	val = dma_readl(od, OWL_DMA_IDLE_STAT);
+
+	return !(val & (1 << pchan->id));
+}
+
+static void owl_dma_terminate_pchan(struct owl_dma *od,
+				    struct owl_dma_pchan *pchan)
+{
+	unsigned long flags;
+	u32 irq_pd;
+
+	pchan_writel(pchan, OWL_DMAX_START, 0);
+	pchan_update(pchan, OWL_DMAX_INT_STATUS, 0xff, false);
+
+	spin_lock_irqsave(&od->lock, flags);
+	dma_update(od, OWL_DMA_IRQ_EN0, (1 << pchan->id), false);
+
+	irq_pd = dma_readl(od, OWL_DMA_IRQ_PD0);
+	if (irq_pd & (1 << pchan->id)) {
+		dev_warn(od->dma.dev,
+			 "terminating pchan %d that still has pending irq\n",
+			 pchan->id);
+		dma_writel(od, OWL_DMA_IRQ_PD0, (1 << pchan->id));
+	}
+
+	pchan->vchan = NULL;
+
+	spin_unlock_irqrestore(&od->lock, flags);
+}
+
+static int owl_dma_start_next_txd(struct owl_dma_vchan *vchan)
+{
+	struct owl_dma *od = to_owl_dma(vchan->vc.chan.device);
+	struct virt_dma_desc *vd = vchan_next_desc(&vchan->vc);
+	struct owl_dma_pchan *pchan = vchan->pchan;
+	struct owl_dma_txd *txd = to_owl_txd(&vd->tx);
+	struct owl_dma_lli *lli;
+	unsigned long flags;
+	u32 int_ctl;
+
+	list_del(&vd->node);
+
+	vchan->txd = txd;
+
+	/* Wait for channel inactive */
+	while (owl_dma_pchan_busy(od, pchan))
+		cpu_relax();
+
+	lli = list_first_entry(&txd->lli_list,
+			       struct owl_dma_lli, node);
+
+	int_ctl = OWL_DMA_INTCTL_SUPER_BLOCK;
+
+	pchan_writel(pchan, OWL_DMAX_MODE, OWL_DMA_MODE_LME);
+	pchan_writel(pchan, OWL_DMAX_LINKLIST_CTL,
+		     OWL_DMA_LLC_SAV_LOAD_NEXT | OWL_DMA_LLC_DAV_LOAD_NEXT);
+	pchan_writel(pchan, OWL_DMAX_NEXT_DESCRIPTOR, lli->phys);
+	pchan_writel(pchan, OWL_DMAX_INT_CTL, int_ctl);
+
+	/* Clear IRQ status for this pchan */
+	pchan_update(pchan, OWL_DMAX_INT_STATUS, 0xff, false);
+
+	spin_lock_irqsave(&od->lock, flags);
+
+	dma_update(od, OWL_DMA_IRQ_EN0, (1 << pchan->id), true);
+
+	spin_unlock_irqrestore(&od->lock, flags);
+
+	dev_dbg(chan2dev(&vchan->vc.chan), "starting pchan %d\n", pchan->id);
+
+	/* Start DMA transfer for this pchan */
+	pchan_writel(pchan, OWL_DMAX_START, 0x1);
+
+	return 0;
+}
+
+static void owl_dma_phy_free(struct owl_dma *od, struct owl_dma_vchan *vchan)
+{
+	/* Ensure that the physical channel is stopped */
+	owl_dma_terminate_pchan(od, vchan->pchan);
+
+	vchan->pchan = NULL;
+}
+
+static irqreturn_t owl_dma_interrupt(int irq, void *dev_id)
+{
+	struct owl_dma *od = dev_id;
+	struct owl_dma_vchan *vchan;
+	struct owl_dma_pchan *pchan;
+	unsigned long pending;
+	int i;
+	unsigned int global_irq_pending, chan_irq_pending;
+
+	spin_lock(&od->lock);
+
+	pending = dma_readl(od, OWL_DMA_IRQ_PD0);
+
+	/* Clear IRQ status for each pchan */
+	for_each_set_bit(i, &pending, od->nr_pchans) {
+		pchan = &od->pchans[i];
+		pchan_update(pchan, OWL_DMAX_INT_STATUS, 0xff, false);
+	}
+
+	/* Clear pending IRQ */
+	dma_writel(od, OWL_DMA_IRQ_PD0, pending);
+
+	/* Check missed pending IRQ */
+	for (i = 0; i < od->nr_pchans; i++) {
+		pchan = &od->pchans[i];
+		chan_irq_pending = pchan_readl(pchan, OWL_DMAX_INT_CTL) &
+				   pchan_readl(pchan, OWL_DMAX_INT_STATUS);
+
+		/* Dummy read to ensure OWL_DMA_IRQ_PD0 value is updated */
+		dma_readl(od, OWL_DMA_IRQ_PD0);
+
+		global_irq_pending = dma_readl(od, OWL_DMA_IRQ_PD0);
+
+		if (chan_irq_pending && !(global_irq_pending & BIT(i)))	{
+			dev_dbg(od->dma.dev,
+				"global and channel IRQ pending match err\n");
+
+			/* Clear IRQ status for this pchan */
+			pchan_update(pchan, OWL_DMAX_INT_STATUS,
+				     0xff, false);
+
+			/* Update global IRQ pending */
+			pending |= BIT(i);
+		}
+	}
+
+	spin_unlock(&od->lock);
+
+	for_each_set_bit(i, &pending, od->nr_pchans) {
+		struct owl_dma_txd *txd;
+
+		pchan = &od->pchans[i];
+
+		vchan = pchan->vchan;
+		if (!vchan) {
+			dev_warn(od->dma.dev, "no vchan attached on pchan %d\n",
+				 pchan->id);
+			continue;
+		}
+
+		spin_lock(&vchan->vc.lock);
+
+		txd = vchan->txd;
+		if (txd) {
+			vchan->txd = NULL;
+
+			vchan_cookie_complete(&txd->vd);
+
+			/*
+			 * Start the next descriptor (if any),
+			 * otherwise free this channel.
+			 */
+			if (vchan_next_desc(&vchan->vc))
+				owl_dma_start_next_txd(vchan);
+			else
+				owl_dma_phy_free(od, vchan);
+		}
+
+		spin_unlock(&vchan->vc.lock);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void owl_dma_free_txd(struct owl_dma *od, struct owl_dma_txd *txd)
+{
+	struct owl_dma_lli *lli, *_lli;
+
+	if (unlikely(!txd))
+		return;
+
+	list_for_each_entry_safe(lli, _lli, &txd->lli_list, node)
+		owl_dma_free_lli(od, lli);
+
+	kfree(txd);
+}
+
+static void owl_dma_desc_free(struct virt_dma_desc *vd)
+{
+	struct owl_dma *od = to_owl_dma(vd->tx.chan->device);
+	struct owl_dma_txd *txd = to_owl_txd(&vd->tx);
+
+	owl_dma_free_txd(od, txd);
+}
+
+static int owl_dma_terminate_all(struct dma_chan *chan)
+{
+	struct owl_dma *od = to_owl_dma(chan->device);
+	struct owl_dma_vchan *vchan = to_owl_vchan(chan);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+
+	if (vchan->pchan)
+		owl_dma_phy_free(od, vchan);
+
+	if (vchan->txd) {
+		owl_dma_desc_free(&vchan->txd->vd);
+		vchan->txd = NULL;
+	}
+
+	vchan_get_all_descriptors(&vchan->vc, &head);
+	vchan_dma_desc_free_list(&vchan->vc, &head);
+
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+	return 0;
+}
+
+static u32 owl_dma_getbytes_chan(struct owl_dma_vchan *vchan)
+{
+	struct owl_dma_pchan *pchan;
+	struct owl_dma_txd *txd;
+	struct owl_dma_lli *lli;
+	unsigned int next_lli_phy;
+	size_t bytes;
+
+	pchan = vchan->pchan;
+	txd = vchan->txd;
+
+	if (!pchan || !txd)
+		return 0;
+
+	/* Get remain count of current node in link list */
+	bytes = pchan_readl(pchan, OWL_DMAX_REMAIN_CNT);
+
+	/* Loop through the preceding nodes to get total remaining bytes */
+	if (pchan_readl(pchan, OWL_DMAX_MODE) & OWL_DMA_MODE_LME) {
+		next_lli_phy = pchan_readl(pchan, OWL_DMAX_NEXT_DESCRIPTOR);
+		list_for_each_entry(lli, &txd->lli_list, node) {
+			/* Start from the next active node */
+			if (lli->phys == next_lli_phy) {
+				list_for_each_entry(lli, &txd->lli_list, node)
+					bytes += lli->hw.flen;
+				break;
+			}
+		}
+	}
+
+	return bytes;
+}
+
+static enum dma_status owl_dma_tx_status(struct dma_chan *chan,
+					 dma_cookie_t cookie,
+					 struct dma_tx_state *state)
+{
+	struct owl_dma_vchan *vchan = to_owl_vchan(chan);
+	struct owl_dma_lli *lli;
+	struct virt_dma_desc *vd;
+	struct owl_dma_txd *txd;
+	enum dma_status ret;
+	unsigned long flags;
+	size_t bytes = 0;
+
+	ret = dma_cookie_status(chan, cookie, state);
+	if (ret == DMA_COMPLETE || !state)
+		return ret;
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+
+	vd = vchan_find_desc(&vchan->vc, cookie);
+	if (vd) {
+		txd = to_owl_txd(&vd->tx);
+		list_for_each_entry(lli, &txd->lli_list, node)
+			bytes += lli->hw.flen;
+	} else {
+		bytes = owl_dma_getbytes_chan(vchan);
+	}
+
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+	dma_set_residue(state, bytes);
+
+	return ret;
+}
+
+static void owl_dma_phy_alloc_and_start(struct owl_dma_vchan *vchan)
+{
+	struct owl_dma *od = to_owl_dma(vchan->vc.chan.device);
+	struct owl_dma_pchan *pchan;
+
+	pchan = owl_dma_get_pchan(od, vchan);
+	if (!pchan)
+		return;
+
+	dev_dbg(od->dma.dev, "allocated pchan %d\n", pchan->id);
+
+	vchan->pchan = pchan;
+	owl_dma_start_next_txd(vchan);
+}
+
+static void owl_dma_issue_pending(struct dma_chan *chan)
+{
+	struct owl_dma_vchan *vchan = to_owl_vchan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+	if (vchan_issue_pending(&vchan->vc)) {
+		if (!vchan->pchan)
+			owl_dma_phy_alloc_and_start(vchan);
+	}
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+}
+
+static struct dma_async_tx_descriptor
+		*owl_dma_prep_memcpy(struct dma_chan *chan,
+				     dma_addr_t dst, dma_addr_t src,
+				     size_t len, unsigned long flags)
+{
+	struct owl_dma *od = to_owl_dma(chan->device);
+	struct owl_dma_vchan *vchan = to_owl_vchan(chan);
+	struct owl_dma_txd *txd;
+	struct owl_dma_lli *lli, *prev = NULL;
+	size_t offset, bytes;
+	int ret;
+
+	if (!len)
+		return NULL;
+
+	txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
+	if (!txd)
+		return NULL;
+
+	INIT_LIST_HEAD(&txd->lli_list);
+
+	/* Process the transfer as frame by frame */
+	for (offset = 0; offset < len; offset += bytes) {
+		lli = owl_dma_alloc_lli(od);
+		if (!lli) {
+			dev_warn(chan2dev(chan), "failed to allocate lli\n");
+			goto err_txd_free;
+		}
+
+		bytes = min_t(size_t, (len - offset), OWL_DMA_FRAME_MAX_LENGTH);
+
+		ret = owl_dma_cfg_lli(vchan, lli, src + offset, dst + offset,
+				      bytes, DMA_MEM_TO_MEM);
+		if (ret) {
+			dev_warn(chan2dev(chan), "failed to config lli\n");
+			goto err_txd_free;
+		}
+
+		prev = owl_dma_add_lli(txd, prev, lli);
+	}
+
+	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
+
+err_txd_free:
+	owl_dma_free_txd(od, txd);
+	return NULL;
+}
+
+static void owl_dma_free_chan_resources(struct dma_chan *chan)
+{
+	struct owl_dma_vchan *vchan = to_owl_vchan(chan);
+
+	/* Ensure all queued descriptors are freed */
+	vchan_free_chan_resources(&vchan->vc);
+}
+
+static inline void owl_dma_free(struct owl_dma *od)
+{
+	struct owl_dma_vchan *vchan = NULL;
+	struct owl_dma_vchan *next;
+
+	list_for_each_entry_safe(vchan,
+				 next, &od->dma.channels, vc.chan.device_node) {
+		list_del(&vchan->vc.chan.device_node);
+		tasklet_kill(&vchan->vc.task);
+	}
+}
+
+static int owl_dma_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct owl_dma *od;
+	struct resource *res;
+	int ret, i, nr_channels, nr_requests;
+
+	od = devm_kzalloc(&pdev->dev, sizeof(*od), GFP_KERNEL);
+	if (!od)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	od->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(od->base))
+		return PTR_ERR(od->base);
+
+	ret = of_property_read_u32(np, "dma-channels", &nr_channels);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get dma-channels\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(np, "dma-requests", &nr_requests);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get dma-requests\n");
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "dma-channels %d, dma-requests %d\n",
+		 nr_channels, nr_requests);
+
+	od->nr_pchans = nr_channels;
+	od->nr_vchans = nr_requests;
+
+	pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+
+	platform_set_drvdata(pdev, od);
+	spin_lock_init(&od->lock);
+
+	dma_cap_set(DMA_MEMCPY, od->dma.cap_mask);
+
+	od->dma.dev = &pdev->dev;
+	od->dma.device_free_chan_resources = owl_dma_free_chan_resources;
+	od->dma.device_tx_status = owl_dma_tx_status;
+	od->dma.device_issue_pending = owl_dma_issue_pending;
+	od->dma.device_prep_dma_memcpy = owl_dma_prep_memcpy;
+	od->dma.device_terminate_all = owl_dma_terminate_all;
+	od->dma.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	od->dma.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	od->dma.directions = BIT(DMA_MEM_TO_MEM);
+	od->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+
+	INIT_LIST_HEAD(&od->dma.channels);
+
+	od->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(od->clk)) {
+		dev_err(&pdev->dev, "unable to get clock\n");
+		return PTR_ERR(od->clk);
+	}
+
+	/*
+	 * Eventhough the DMA controller is capable of generating 4
+	 * IRQ's for DMA priority feature, we only use 1 IRQ for
+	 * simplification.
+	 */
+	od->irq = platform_get_irq(pdev, 0);
+	ret = devm_request_irq(&pdev->dev, od->irq, owl_dma_interrupt, 0,
+			       dev_name(&pdev->dev), od);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to request IRQ\n");
+		return ret;
+	}
+
+	/* Init physical channel */
+	od->pchans = devm_kcalloc(&pdev->dev, od->nr_pchans,
+				  sizeof(struct owl_dma_pchan), GFP_KERNEL);
+	if (!od->pchans)
+		return -ENOMEM;
+
+	for (i = 0; i < od->nr_pchans; i++) {
+		struct owl_dma_pchan *pchan = &od->pchans[i];
+
+		pchan->id = i;
+		pchan->base = od->base + OWL_DMA_CHAN_BASE(i);
+	}
+
+	/* Init virtual channel */
+	od->vchans = devm_kcalloc(&pdev->dev, od->nr_vchans,
+				  sizeof(struct owl_dma_vchan), GFP_KERNEL);
+	if (!od->vchans)
+		return -ENOMEM;
+
+	for (i = 0; i < od->nr_vchans; i++) {
+		struct owl_dma_vchan *vchan = &od->vchans[i];
+
+		vchan->vc.desc_free = owl_dma_desc_free;
+		vchan_init(&vchan->vc, &od->dma);
+	}
+
+	/* Create a pool of consistent memory blocks for hardware descriptors */
+	od->lli_pool = dma_pool_create(dev_name(od->dma.dev), od->dma.dev,
+				       sizeof(struct owl_dma_lli),
+				       __alignof__(struct owl_dma_lli),
+				       0);
+	if (!od->lli_pool) {
+		dev_err(&pdev->dev, "unable to allocate DMA descriptor pool\n");
+		return -ENOMEM;
+	}
+
+	clk_prepare_enable(od->clk);
+
+	ret = dma_async_device_register(&od->dma);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register DMA engine device\n");
+		goto err_pool_free;
+	}
+
+	return 0;
+
+err_pool_free:
+	clk_disable_unprepare(od->clk);
+	dma_pool_destroy(od->lli_pool);
+
+	return ret;
+}
+
+static int owl_dma_remove(struct platform_device *pdev)
+{
+	struct owl_dma *od = platform_get_drvdata(pdev);
+
+	dma_async_device_unregister(&od->dma);
+
+	/* Mask all interrupts for this execution environment */
+	dma_writel(od, OWL_DMA_IRQ_EN0, 0x0);
+
+	/* Make sure we won't have any further interrupts */
+	devm_free_irq(od->dma.dev, od->irq, od);
+
+	owl_dma_free(od);
+
+	clk_disable_unprepare(od->clk);
+
+	return 0;
+}
+
+static const struct of_device_id owl_dma_match[] = {
+	{ .compatible = "actions,s900-dma", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, owl_dma_match);
+
+static struct platform_driver owl_dma_driver = {
+	.probe	= owl_dma_probe,
+	.remove	= owl_dma_remove,
+	.driver = {
+		.name = "dma-owl",
+		.of_match_table = of_match_ptr(owl_dma_match),
+	},
+};
+
+static int owl_dma_init(void)
+{
+	return platform_driver_register(&owl_dma_driver);
+}
+subsys_initcall(owl_dma_init);
+
+static void __exit owl_dma_exit(void)
+{
+	platform_driver_unregister(&owl_dma_driver);
+}
+module_exit(owl_dma_exit);
+
+MODULE_AUTHOR("David Liu <liuwei@xxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Actions Semi Owl SoCs DMA driver");
+MODULE_LICENSE("GPL");
-- 
2.17.1