Merge branch 'topic/mtek' into for-linus

Documentation/devicetree/bindings/dma/mtk-hsdma.txt

+MediaTek High-Speed DMA Controller
+==================================
+
+This device follows the generic DMA bindings defined in dma/dma.txt.
+
+Required properties:
+
+- compatible:	Must be one of
+		  "mediatek,mt7622-hsdma": for MT7622 SoC
+		  "mediatek,mt7623-hsdma": for MT7623 SoC
+- reg:		Should contain the register's base address and length.
+- interrupts:	Should contain a reference to the interrupt used by this
+		device.
+- clocks:	Should be the clock specifiers corresponding to the entry in
+		clock-names property.
+- clock-names:	Should contain "hsdma" entries.
+- power-domains: Phandle to the power domain that the device is part of
+- #dma-cells: 	The length of the DMA specifier, must be <1>. This one cell
+		in dmas property of a client device represents the channel
+		number.
+Example:
+
+        hsdma: dma-controller@1b007000 {
+		compatible = "mediatek,mt7623-hsdma";
+		reg = <0 0x1b007000 0 0x1000>;
+		interrupts = <GIC_SPI 98 IRQ_TYPE_LEVEL_LOW>;
+		clocks = <&ethsys CLK_ETHSYS_HSDMA>;
+		clock-names = "hsdma";
+		power-domains = <&scpsys MT2701_POWER_DOMAIN_ETH>;
+		#dma-cells = <1>;
+	};
+
+DMA clients must use the format described in dma/dma.txt file.

MAINTAINERS

@@ -8785,6 +8785,15 @@ M:	Sean Wang <sean.wang@mediatek.com>
 S:	Maintained
 F:	drivers/media/rc/mtk-cir.c
 
+MEDIATEK DMA DRIVER
+M:	Sean Wang <sean.wang@mediatek.com>
+L:	dmaengine@vger.kernel.org
+L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
+L:	linux-mediatek@lists.infradead.org (moderated for non-subscribers)
+S:	Maintained
+F:	Documentation/devicetree/bindings/dma/mtk-*
+F:	drivers/dma/mediatek/
+
 MEDIATEK PMIC LED DRIVER
 M:	Sean Wang <sean.wang@mediatek.com>
 S:	Maintained

drivers/dma/Kconfig

@@ -643,6 +643,8 @@ config ZX_DMA
 # driver files
 source "drivers/dma/bestcomm/Kconfig"
 
+source "drivers/dma/mediatek/Kconfig"
+
 source "drivers/dma/qcom/Kconfig"
 
 source "drivers/dma/dw/Kconfig"

drivers/dma/Makefile

@@ -76,5 +76,6 @@ obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
 obj-$(CONFIG_ZX_DMA) += zx_dma.o
 obj-$(CONFIG_ST_FDMA) += st_fdma.o
 
+obj-y += mediatek/
 obj-y += qcom/
 obj-y += xilinx/

drivers/dma/mediatek/Kconfig

+
+config MTK_HSDMA
+	tristate "MediaTek High-Speed DMA controller support"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	---help---
+	  Enable support for High-Speed DMA controller on MediaTek
+	  SoCs.
+
+	  This controller provides the channels which is dedicated to
+	  memory-to-memory transfer to offload from CPU through ring-
+	  based descriptor management.

drivers/dma/mediatek/Makefile

+obj-$(CONFIG_MTK_HSDMA) += mtk-hsdma.o

drivers/dma/mediatek/mtk-hsdma.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017-2018 MediaTek Inc.
+
+/*
+ * Driver for MediaTek High-Speed DMA Controller
+ *
+ * Author: Sean Wang <sean.wang@mediatek.com>
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/iopoll.h>
+#include <linux/list.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/pm_runtime.h>
+#include <linux/refcount.h>
+#include <linux/slab.h>
+
+#include "../virt-dma.h"
+
+#define MTK_HSDMA_USEC_POLL		20
+#define MTK_HSDMA_TIMEOUT_POLL		200000
+#define MTK_HSDMA_DMA_BUSWIDTHS		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES)
+
+/* The default number of virtual channel */
+#define MTK_HSDMA_NR_VCHANS		3
+
+/* Only one physical channel supported */
+#define MTK_HSDMA_NR_MAX_PCHANS		1
+
+/* Macro for physical descriptor (PD) manipulation */
+/* The number of PD which must be 2 of power */
+#define MTK_DMA_SIZE			64
+#define MTK_HSDMA_NEXT_DESP_IDX(x, y)	(((x) + 1) & ((y) - 1))
+#define MTK_HSDMA_LAST_DESP_IDX(x, y)	(((x) - 1) & ((y) - 1))
+#define MTK_HSDMA_MAX_LEN		0x3f80
+#define MTK_HSDMA_ALIGN_SIZE		4
+#define MTK_HSDMA_PLEN_MASK		0x3fff
+#define MTK_HSDMA_DESC_PLEN(x)		(((x) & MTK_HSDMA_PLEN_MASK) << 16)
+#define MTK_HSDMA_DESC_PLEN_GET(x)	(((x) >> 16) & MTK_HSDMA_PLEN_MASK)
+
+/* Registers for underlying ring manipulation */
+#define MTK_HSDMA_TX_BASE		0x0
+#define MTK_HSDMA_TX_CNT		0x4
+#define MTK_HSDMA_TX_CPU		0x8
+#define MTK_HSDMA_TX_DMA		0xc
+#define MTK_HSDMA_RX_BASE		0x100
+#define MTK_HSDMA_RX_CNT		0x104
+#define MTK_HSDMA_RX_CPU		0x108
+#define MTK_HSDMA_RX_DMA		0x10c
+
+/* Registers for global setup */
+#define MTK_HSDMA_GLO			0x204
+#define MTK_HSDMA_GLO_MULTI_DMA		BIT(10)
+#define MTK_HSDMA_TX_WB_DDONE		BIT(6)
+#define MTK_HSDMA_BURST_64BYTES		(0x2 << 4)
+#define MTK_HSDMA_GLO_RX_BUSY		BIT(3)
+#define MTK_HSDMA_GLO_RX_DMA		BIT(2)
+#define MTK_HSDMA_GLO_TX_BUSY		BIT(1)
+#define MTK_HSDMA_GLO_TX_DMA		BIT(0)
+#define MTK_HSDMA_GLO_DMA		(MTK_HSDMA_GLO_TX_DMA |	\
+					 MTK_HSDMA_GLO_RX_DMA)
+#define MTK_HSDMA_GLO_BUSY		(MTK_HSDMA_GLO_RX_BUSY | \
+					 MTK_HSDMA_GLO_TX_BUSY)
+#define MTK_HSDMA_GLO_DEFAULT		(MTK_HSDMA_GLO_TX_DMA | \
+					 MTK_HSDMA_GLO_RX_DMA | \
+					 MTK_HSDMA_TX_WB_DDONE | \
+					 MTK_HSDMA_BURST_64BYTES | \
+					 MTK_HSDMA_GLO_MULTI_DMA)
+
+/* Registers for reset */
+#define MTK_HSDMA_RESET			0x208
+#define MTK_HSDMA_RST_TX		BIT(0)
+#define MTK_HSDMA_RST_RX		BIT(16)
+
+/* Registers for interrupt control */
+#define MTK_HSDMA_DLYINT		0x20c
+#define MTK_HSDMA_RXDLY_INT_EN		BIT(15)
+
+/* Interrupt fires when the pending number's more than the specified */
+#define MTK_HSDMA_RXMAX_PINT(x)		(((x) & 0x7f) << 8)
+
+/* Interrupt fires when the pending time's more than the specified in 20 us */
+#define MTK_HSDMA_RXMAX_PTIME(x)	((x) & 0x7f)
+#define MTK_HSDMA_DLYINT_DEFAULT	(MTK_HSDMA_RXDLY_INT_EN | \
+					 MTK_HSDMA_RXMAX_PINT(20) | \
+					 MTK_HSDMA_RXMAX_PTIME(20))
+#define MTK_HSDMA_INT_STATUS		0x220
+#define MTK_HSDMA_INT_ENABLE		0x228
+#define MTK_HSDMA_INT_RXDONE		BIT(16)
+
+enum mtk_hsdma_vdesc_flag {
+	MTK_HSDMA_VDESC_FINISHED	= 0x01,
+};
+
+#define IS_MTK_HSDMA_VDESC_FINISHED(x) ((x) == MTK_HSDMA_VDESC_FINISHED)
+
+/**
+ * struct mtk_hsdma_pdesc - This is the struct holding info describing physical
+ *			    descriptor (PD) and its placement must be kept at
+ *			    4-bytes alignment in little endian order.
+ * @desc[1-4]:		    The control pad used to indicate hardware how to
+ *			    deal with the descriptor such as source and
+ *			    destination address and data length. The maximum
+ *			    data length each pdesc can handle is 0x3f80 bytes
+ */
+struct mtk_hsdma_pdesc {
+	__le32 desc1;
+	__le32 desc2;
+	__le32 desc3;
+	__le32 desc4;
+} __packed __aligned(4);
+
+/**
+ * struct mtk_hsdma_vdesc - This is the struct holding info describing virtual
+ *			    descriptor (VD)
+ * @vd:			    An instance for struct virt_dma_desc
+ * @len:		    The total data size device wants to move
+ * @residue:		    The remaining data size device will move
+ * @dest:		    The destination address device wants to move to
+ * @src:		    The source address device wants to move from
+ */
+struct mtk_hsdma_vdesc {
+	struct virt_dma_desc vd;
+	size_t len;
+	size_t residue;
+	dma_addr_t dest;
+	dma_addr_t src;
+};
+
+/**
+ * struct mtk_hsdma_cb - This is the struct holding extra info required for RX
+ *			 ring to know what relevant VD the the PD is being
+ *			 mapped to.
+ * @vd:			 Pointer to the relevant VD.
+ * @flag:		 Flag indicating what action should be taken when VD
+ *			 is completed.
+ */
+struct mtk_hsdma_cb {
+	struct virt_dma_desc *vd;
+	enum mtk_hsdma_vdesc_flag flag;
+};
+
+/**
+ * struct mtk_hsdma_ring - This struct holds info describing underlying ring
+ *			   space
+ * @txd:		   The descriptor TX ring which describes DMA source
+ *			   information
+ * @rxd:		   The descriptor RX ring which describes DMA
+ *			   destination information
+ * @cb:			   The extra information pointed at by RX ring
+ * @tphys:		   The physical addr of TX ring
+ * @rphys:		   The physical addr of RX ring
+ * @cur_tptr:		   Pointer to the next free descriptor used by the host
+ * @cur_rptr:		   Pointer to the last done descriptor by the device
+ */
+struct mtk_hsdma_ring {
+	struct mtk_hsdma_pdesc *txd;
+	struct mtk_hsdma_pdesc *rxd;
+	struct mtk_hsdma_cb *cb;
+	dma_addr_t tphys;
+	dma_addr_t rphys;
+	u16 cur_tptr;
+	u16 cur_rptr;
+};
+
+/**
+ * struct mtk_hsdma_pchan - This is the struct holding info describing physical
+ *			   channel (PC)
+ * @ring:		   An instance for the underlying ring
+ * @sz_ring:		   Total size allocated for the ring
+ * @nr_free:		   Total number of free rooms in the ring. It would
+ *			   be accessed and updated frequently between IRQ
+ *			   context and user context to reflect whether ring
+ *			   can accept requests from VD.
+ */
+struct mtk_hsdma_pchan {
+	struct mtk_hsdma_ring ring;
+	size_t sz_ring;
+	atomic_t nr_free;
+};
+
+/**
+ * struct mtk_hsdma_vchan - This is the struct holding info describing virtual
+ *			   channel (VC)
+ * @vc:			   An instance for struct virt_dma_chan
+ * @issue_completion:	   The wait for all issued descriptors completited
+ * @issue_synchronize:	   Bool indicating channel synchronization starts
+ * @desc_hw_processing:	   List those descriptors the hardware is processing,
+ *			   which is protected by vc.lock
+ */
+struct mtk_hsdma_vchan {
+	struct virt_dma_chan vc;
+	struct completion issue_completion;
+	bool issue_synchronize;
+	struct list_head desc_hw_processing;
+};
+
+/**
+ * struct mtk_hsdma_soc - This is the struct holding differences among SoCs
+ * @ddone:		  Bit mask for DDONE
+ * @ls0:		  Bit mask for LS0
+ */
+struct mtk_hsdma_soc {
+	__le32 ddone;
+	__le32 ls0;
+};
+
+/**
+ * struct mtk_hsdma_device - This is the struct holding info describing HSDMA
+ *			     device
+ * @ddev:		     An instance for struct dma_device
+ * @base:		     The mapped register I/O base
+ * @clk:		     The clock that device internal is using
+ * @irq:		     The IRQ that device are using
+ * @dma_requests:	     The number of VCs the device supports to
+ * @vc:			     The pointer to all available VCs
+ * @pc:			     The pointer to the underlying PC
+ * @pc_refcnt:		     Track how many VCs are using the PC
+ * @lock:		     Lock protect agaisting multiple VCs access PC
+ * @soc:		     The pointer to area holding differences among
+ *			     vaious platform
+ */
+struct mtk_hsdma_device {
+	struct dma_device ddev;
+	void __iomem *base;
+	struct clk *clk;
+	u32 irq;
+
+	u32 dma_requests;
+	struct mtk_hsdma_vchan *vc;
+	struct mtk_hsdma_pchan *pc;
+	refcount_t pc_refcnt;
+
+	/* Lock used to protect against multiple VCs access PC */
+	spinlock_t lock;
+
+	const struct mtk_hsdma_soc *soc;
+};
+
+static struct mtk_hsdma_device *to_hsdma_dev(struct dma_chan *chan)
+{
+	return container_of(chan->device, struct mtk_hsdma_device, ddev);
+}
+
+static inline struct mtk_hsdma_vchan *to_hsdma_vchan(struct dma_chan *chan)
+{
+	return container_of(chan, struct mtk_hsdma_vchan, vc.chan);
+}
+
+static struct mtk_hsdma_vdesc *to_hsdma_vdesc(struct virt_dma_desc *vd)
+{
+	return container_of(vd, struct mtk_hsdma_vdesc, vd);
+}
+
+static struct device *hsdma2dev(struct mtk_hsdma_device *hsdma)
+{
+	return hsdma->ddev.dev;
+}
+
+static u32 mtk_dma_read(struct mtk_hsdma_device *hsdma, u32 reg)
+{
+	return readl(hsdma->base + reg);
+}
+
+static void mtk_dma_write(struct mtk_hsdma_device *hsdma, u32 reg, u32 val)
+{
+	writel(val, hsdma->base + reg);
+}
+
+static void mtk_dma_rmw(struct mtk_hsdma_device *hsdma, u32 reg,
+			u32 mask, u32 set)
+{
+	u32 val;
+
+	val = mtk_dma_read(hsdma, reg);
+	val &= ~mask;
+	val |= set;
+	mtk_dma_write(hsdma, reg, val);
+}
+
+static void mtk_dma_set(struct mtk_hsdma_device *hsdma, u32 reg, u32 val)
+{
+	mtk_dma_rmw(hsdma, reg, 0, val);
+}
+
+static void mtk_dma_clr(struct mtk_hsdma_device *hsdma, u32 reg, u32 val)
+{
+	mtk_dma_rmw(hsdma, reg, val, 0);
+}
+
+static void mtk_hsdma_vdesc_free(struct virt_dma_desc *vd)
+{
+	kfree(container_of(vd, struct mtk_hsdma_vdesc, vd));
+}
+
+static int mtk_hsdma_busy_wait(struct mtk_hsdma_device *hsdma)
+{
+	u32 status = 0;
+
+	return readl_poll_timeout(hsdma->base + MTK_HSDMA_GLO, status,
+				  !(status & MTK_HSDMA_GLO_BUSY),
+				  MTK_HSDMA_USEC_POLL,
+				  MTK_HSDMA_TIMEOUT_POLL);
+}
+
+static int mtk_hsdma_alloc_pchan(struct mtk_hsdma_device *hsdma,
+				 struct mtk_hsdma_pchan *pc)
+{
+	struct mtk_hsdma_ring *ring = &pc->ring;
+	int err;
+
+	memset(pc, 0, sizeof(*pc));
+
+	/*
+	 * Allocate ring space where [0 ... MTK_DMA_SIZE - 1] is for TX ring
+	 * and [MTK_DMA_SIZE ... 2 * MTK_DMA_SIZE - 1] is for RX ring.
+	 */
+	pc->sz_ring = 2 * MTK_DMA_SIZE * sizeof(*ring->txd);
+	ring->txd = dma_zalloc_coherent(hsdma2dev(hsdma), pc->sz_ring,
+					&ring->tphys, GFP_NOWAIT);
+	if (!ring->txd)
+		return -ENOMEM;
+
+	ring->rxd = &ring->txd[MTK_DMA_SIZE];
+	ring->rphys = ring->tphys + MTK_DMA_SIZE * sizeof(*ring->txd);
+	ring->cur_tptr = 0;
+	ring->cur_rptr = MTK_DMA_SIZE - 1;
+
+	ring->cb = kcalloc(MTK_DMA_SIZE, sizeof(*ring->cb), GFP_NOWAIT);
+	if (!ring->cb) {
+		err = -ENOMEM;
+		goto err_free_dma;
+	}
+
+	atomic_set(&pc->nr_free, MTK_DMA_SIZE - 1);
+
+	/* Disable HSDMA and wait for the completion */
+	mtk_dma_clr(hsdma, MTK_HSDMA_GLO, MTK_HSDMA_GLO_DMA);
+	err = mtk_hsdma_busy_wait(hsdma);
+	if (err)
+		goto err_free_cb;
+
+	/* Reset */
+	mtk_dma_set(hsdma, MTK_HSDMA_RESET,
+		    MTK_HSDMA_RST_TX | MTK_HSDMA_RST_RX);
+	mtk_dma_clr(hsdma, MTK_HSDMA_RESET,
+		    MTK_HSDMA_RST_TX | MTK_HSDMA_RST_RX);
+
+	/* Setup HSDMA initial pointer in the ring */
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_BASE, ring->tphys);
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_CNT, MTK_DMA_SIZE);
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_CPU, ring->cur_tptr);
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_DMA, 0);
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_BASE, ring->rphys);
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_CNT, MTK_DMA_SIZE);
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_CPU, ring->cur_rptr);
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_DMA, 0);
+
+	/* Enable HSDMA */
+	mtk_dma_set(hsdma, MTK_HSDMA_GLO, MTK_HSDMA_GLO_DMA);
+
+	/* Setup delayed interrupt */
+	mtk_dma_write(hsdma, MTK_HSDMA_DLYINT, MTK_HSDMA_DLYINT_DEFAULT);
+
+	/* Enable interrupt */
+	mtk_dma_set(hsdma, MTK_HSDMA_INT_ENABLE, MTK_HSDMA_INT_RXDONE);
+
+	return 0;
+
+err_free_cb:
+	kfree(ring->cb);
+
+err_free_dma:
+	dma_free_coherent(hsdma2dev(hsdma),
+			  pc->sz_ring, ring->txd, ring->tphys);
+	return err;
+}
+
+static void mtk_hsdma_free_pchan(struct mtk_hsdma_device *hsdma,
+				 struct mtk_hsdma_pchan *pc)
+{
+	struct mtk_hsdma_ring *ring = &pc->ring;
+
+	/* Disable HSDMA and then wait for the completion */
+	mtk_dma_clr(hsdma, MTK_HSDMA_GLO, MTK_HSDMA_GLO_DMA);
+	mtk_hsdma_busy_wait(hsdma);
+
+	/* Reset pointer in the ring */
+	mtk_dma_clr(hsdma, MTK_HSDMA_INT_ENABLE, MTK_HSDMA_INT_RXDONE);
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_BASE, 0);
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_CNT, 0);
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_CPU, 0);
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_BASE, 0);
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_CNT, 0);
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_CPU, MTK_DMA_SIZE - 1);
+
+	kfree(ring->cb);
+
+	dma_free_coherent(hsdma2dev(hsdma),
+			  pc->sz_ring, ring->txd, ring->tphys);
+}
+
+static int mtk_hsdma_issue_pending_vdesc(struct mtk_hsdma_device *hsdma,
+					 struct mtk_hsdma_pchan *pc,
+					 struct mtk_hsdma_vdesc *hvd)
+{
+	struct mtk_hsdma_ring *ring = &pc->ring;
+	struct mtk_hsdma_pdesc *txd, *rxd;
+	u16 reserved, prev, tlen, num_sgs;
+	unsigned long flags;
+
+	/* Protect against PC is accessed by multiple VCs simultaneously */
+	spin_lock_irqsave(&hsdma->lock, flags);
+
+	/*
+	 * Reserve rooms, where pc->nr_free is used to track how many free
+	 * rooms in the ring being updated in user and IRQ context.
+	 */
+	num_sgs = DIV_ROUND_UP(hvd->len, MTK_HSDMA_MAX_LEN);
+	reserved = min_t(u16, num_sgs, atomic_read(&pc->nr_free));
+
+	if (!reserved) {
+		spin_unlock_irqrestore(&hsdma->lock, flags);
+		return -ENOSPC;
+	}
+
+	atomic_sub(reserved, &pc->nr_free);
+
+	while (reserved--) {
+		/* Limit size by PD capability for valid data moving */
+		tlen = (hvd->len > MTK_HSDMA_MAX_LEN) ?
+		       MTK_HSDMA_MAX_LEN : hvd->len;
+
+		/*
+		 * Setup PDs using the remaining VD info mapped on those
+		 * reserved rooms. And since RXD is shared memory between the
+		 * host and the device allocated by dma_alloc_coherent call,
+		 * the helper macro WRITE_ONCE can ensure the data written to
+		 * RAM would really happens.
+		 */
+		txd = &ring->txd[ring->cur_tptr];
+		WRITE_ONCE(txd->desc1, hvd->src);
+		WRITE_ONCE(txd->desc2,
+			   hsdma->soc->ls0 | MTK_HSDMA_DESC_PLEN(tlen));
+
+		rxd = &ring->rxd[ring->cur_tptr];
+		WRITE_ONCE(rxd->desc1, hvd->dest);
+		WRITE_ONCE(rxd->desc2, MTK_HSDMA_DESC_PLEN(tlen));
+
+		/* Associate VD, the PD belonged to */
+		ring->cb[ring->cur_tptr].vd = &hvd->vd;
+
+		/* Move forward the pointer of TX ring */
+		ring->cur_tptr = MTK_HSDMA_NEXT_DESP_IDX(ring->cur_tptr,
+							 MTK_DMA_SIZE);
+
+		/* Update VD with remaining data */
+		hvd->src  += tlen;
+		hvd->dest += tlen;
+		hvd->len  -= tlen;
+	}
+
+	/*
+	 * Tagging flag for the last PD for VD will be responsible for
+	 * completing VD.
+	 */
+	if (!hvd->len) {
+		prev = MTK_HSDMA_LAST_DESP_IDX(ring->cur_tptr, MTK_DMA_SIZE);
+		ring->cb[prev].flag = MTK_HSDMA_VDESC_FINISHED;
+	}
+
+	/* Ensure all changes indeed done before we're going on */
+	wmb();
+
+	/*
+	 * Updating into hardware the pointer of TX ring lets HSDMA to take
+	 * action for those pending PDs.
+	 */
+	mtk_dma_write(hsdma, MTK_HSDMA_TX_CPU, ring->cur_tptr);
+
+	spin_unlock_irqrestore(&hsdma->lock, flags);
+
+	return 0;
+}
+
+static void mtk_hsdma_issue_vchan_pending(struct mtk_hsdma_device *hsdma,
+					  struct mtk_hsdma_vchan *hvc)
+{
+	struct virt_dma_desc *vd, *vd2;
+	int err;
+
+	lockdep_assert_held(&hvc->vc.lock);
+
+	list_for_each_entry_safe(vd, vd2, &hvc->vc.desc_issued, node) {
+		struct mtk_hsdma_vdesc *hvd;
+
+		hvd = to_hsdma_vdesc(vd);
+
+		/* Map VD into PC and all VCs shares a single PC */
+		err = mtk_hsdma_issue_pending_vdesc(hsdma, hsdma->pc, hvd);
+
+		/*
+		 * Move VD from desc_issued to desc_hw_processing when entire
+		 * VD is fit into available PDs. Otherwise, the uncompleted
+		 * VDs would stay in list desc_issued and then restart the
+		 * processing as soon as possible once underlying ring space
+		 * got freed.
+		 */
+		if (err == -ENOSPC || hvd->len > 0)
+			break;
+
+		/*
+		 * The extra list desc_hw_processing is used because
+		 * hardware can't provide sufficient information allowing us
+		 * to know what VDs are still working on the underlying ring.
+		 * Through the additional list, it can help us to implement
+		 * terminate_all, residue calculation and such thing needed
+		 * to know detail descriptor status on the hardware.
+		 */
+		list_move_tail(&vd->node, &hvc->desc_hw_processing);
+	}
+}
+
+static void mtk_hsdma_free_rooms_in_ring(struct mtk_hsdma_device *hsdma)
+{
+	struct mtk_hsdma_vchan *hvc;
+	struct mtk_hsdma_pdesc *rxd;
+	struct mtk_hsdma_vdesc *hvd;
+	struct mtk_hsdma_pchan *pc;
+	struct mtk_hsdma_cb *cb;
+	int i = MTK_DMA_SIZE;
+	__le32 desc2;
+	u32 status;
+	u16 next;
+
+	/* Read IRQ status */
+	status = mtk_dma_read(hsdma, MTK_HSDMA_INT_STATUS);
+	if (unlikely(!(status & MTK_HSDMA_INT_RXDONE)))
+		goto rx_done;
+
+	pc = hsdma->pc;
+
+	/*
+	 * Using a fail-safe loop with iterations of up to MTK_DMA_SIZE to
+	 * reclaim these finished descriptors: The most number of PDs the ISR
+	 * can handle at one time shouldn't be more than MTK_DMA_SIZE so we
+	 * take it as limited count instead of just using a dangerous infinite
+	 * poll.
+	 */
+	while (i--) {
+		next = MTK_HSDMA_NEXT_DESP_IDX(pc->ring.cur_rptr,
+					       MTK_DMA_SIZE);
+		rxd = &pc->ring.rxd[next];
+
+		/*
+		 * If MTK_HSDMA_DESC_DDONE is no specified, that means data
+		 * moving for the PD is still under going.
+		 */
+		desc2 = READ_ONCE(rxd->desc2);
+		if (!(desc2 & hsdma->soc->ddone))
+			break;
+
+		cb = &pc->ring.cb[next];
+		if (unlikely(!cb->vd)) {
+			dev_err(hsdma2dev(hsdma), "cb->vd cannot be null\n");
+			break;
+		}
+
+		/* Update residue of VD the associated PD belonged to */
+		hvd = to_hsdma_vdesc(cb->vd);
+		hvd->residue -= MTK_HSDMA_DESC_PLEN_GET(rxd->desc2);
+
+		/* Complete VD until the relevant last PD is finished */
+		if (IS_MTK_HSDMA_VDESC_FINISHED(cb->flag)) {
+			hvc = to_hsdma_vchan(cb->vd->tx.chan);
+
+			spin_lock(&hvc->vc.lock);
+
+			/* Remove VD from list desc_hw_processing */
+			list_del(&cb->vd->node);
+
+			/* Add VD into list desc_completed */
+			vchan_cookie_complete(cb->vd);
+
+			if (hvc->issue_synchronize &&
+			    list_empty(&hvc->desc_hw_processing)) {
+				complete(&hvc->issue_completion);
+				hvc->issue_synchronize = false;
+			}
+			spin_unlock(&hvc->vc.lock);
+
+			cb->flag = 0;
+		}
+
+		cb->vd = 0;
+
+		/*
+		 * Recycle the RXD with the helper WRITE_ONCE that can ensure
+		 * data written into RAM would really happens.
+		 */
+		WRITE_ONCE(rxd->desc1, 0);
+		WRITE_ONCE(rxd->desc2, 0);
+		pc->ring.cur_rptr = next;
+
+		/* Release rooms */
+		atomic_inc(&pc->nr_free);
+	}
+
+	/* Ensure all changes indeed done before we're going on */
+	wmb();
+
+	/* Update CPU pointer for those completed PDs */
+	mtk_dma_write(hsdma, MTK_HSDMA_RX_CPU, pc->ring.cur_rptr);
+
+	/*
+	 * Acking the pending IRQ allows hardware no longer to keep the used
+	 * IRQ line in certain trigger state when software has completed all
+	 * the finished physical descriptors.
+	 */
+	if (atomic_read(&pc->nr_free) >= MTK_DMA_SIZE - 1)
+		mtk_dma_write(hsdma, MTK_HSDMA_INT_STATUS, status);
+
+	/* ASAP handles pending VDs in all VCs after freeing some rooms */
+	for (i = 0; i < hsdma->dma_requests; i++) {
+		hvc = &hsdma->vc[i];
+		spin_lock(&hvc->vc.lock);
+		mtk_hsdma_issue_vchan_pending(hsdma, hvc);
+		spin_unlock(&hvc->vc.lock);
+	}
+
+rx_done:
+	/* All completed PDs are cleaned up, so enable interrupt again */
+	mtk_dma_set(hsdma, MTK_HSDMA_INT_ENABLE, MTK_HSDMA_INT_RXDONE);
+}
+
+static irqreturn_t mtk_hsdma_irq(int irq, void *devid)
+{
+	struct mtk_hsdma_device *hsdma = devid;
+
+	/*
+	 * Disable interrupt until all completed PDs are cleaned up in
+	 * mtk_hsdma_free_rooms call.
+	 */
+	mtk_dma_clr(hsdma, MTK_HSDMA_INT_ENABLE, MTK_HSDMA_INT_RXDONE);
+
+	mtk_hsdma_free_rooms_in_ring(hsdma);
+
+	return IRQ_HANDLED;
+}
+
+static struct virt_dma_desc *mtk_hsdma_find_active_desc(struct dma_chan *c,
+							dma_cookie_t cookie)
+{
+	struct mtk_hsdma_vchan *hvc = to_hsdma_vchan(c);
+	struct virt_dma_desc *vd;
+
+	list_for_each_entry(vd, &hvc->desc_hw_processing, node)
+		if (vd->tx.cookie == cookie)
+			return vd;
+
+	list_for_each_entry(vd, &hvc->vc.desc_issued, node)
+		if (vd->tx.cookie == cookie)
+			return vd;
+
+	return NULL;
+}
+
+static enum dma_status mtk_hsdma_tx_status(struct dma_chan *c,
+					   dma_cookie_t cookie,
+					   struct dma_tx_state *txstate)
+{
+	struct mtk_hsdma_vchan *hvc = to_hsdma_vchan(c);
+	struct mtk_hsdma_vdesc *hvd;
+	struct virt_dma_desc *vd;
+	enum dma_status ret;
+	unsigned long flags;
+	size_t bytes = 0;
+
+	ret = dma_cookie_status(c, cookie, txstate);
+	if (ret == DMA_COMPLETE || !txstate)
+		return ret;
+
+	spin_lock_irqsave(&hvc->vc.lock, flags);
+	vd = mtk_hsdma_find_active_desc(c, cookie);
+	spin_unlock_irqrestore(&hvc->vc.lock, flags);
+
+	if (vd) {
+		hvd = to_hsdma_vdesc(vd);
+		bytes = hvd->residue;
+	}
+
+	dma_set_residue(txstate, bytes);
+
+	return ret;
+}
+
+static void mtk_hsdma_issue_pending(struct dma_chan *c)
+{
+	struct mtk_hsdma_device *hsdma = to_hsdma_dev(c);
+	struct mtk_hsdma_vchan *hvc = to_hsdma_vchan(c);
+	unsigned long flags;
+
+	spin_lock_irqsave(&hvc->vc.lock, flags);
+
+	if (vchan_issue_pending(&hvc->vc))
+		mtk_hsdma_issue_vchan_pending(hsdma, hvc);
+
+	spin_unlock_irqrestore(&hvc->vc.lock, flags);
+}
+
+static struct dma_async_tx_descriptor *
+mtk_hsdma_prep_dma_memcpy(struct dma_chan *c, dma_addr_t dest,
+			  dma_addr_t src, size_t len, unsigned long flags)
+{
+	struct mtk_hsdma_vdesc *hvd;
+
+	hvd = kzalloc(sizeof(*hvd), GFP_NOWAIT);
+	if (!hvd)
+		return NULL;
+
+	hvd->len = len;
+	hvd->residue = len;
+	hvd->src = src;
+	hvd->dest = dest;
+
+	return vchan_tx_prep(to_virt_chan(c), &hvd->vd, flags);
+}
+
+static int mtk_hsdma_free_inactive_desc(struct dma_chan *c)
+{
+	struct virt_dma_chan *vc = to_virt_chan(c);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&vc->lock, flags);
+	list_splice_tail_init(&vc->desc_allocated, &head);
+	list_splice_tail_init(&vc->desc_submitted, &head);
+	list_splice_tail_init(&vc->desc_issued, &head);
+	spin_unlock_irqrestore(&vc->lock, flags);
+
+	/* At the point, we don't expect users put descriptor into VC again */
+	vchan_dma_desc_free_list(vc, &head);
+
+	return 0;
+}
+
+static void mtk_hsdma_free_active_desc(struct dma_chan *c)
+{
+	struct mtk_hsdma_vchan *hvc = to_hsdma_vchan(c);
+	bool sync_needed = false;
+
+	/*
+	 * Once issue_synchronize is being set, which means once the hardware
+	 * consumes all descriptors for the channel in the ring, the
+	 * synchronization must be be notified immediately it is completed.
+	 */
+	spin_lock(&hvc->vc.lock);
+	if (!list_empty(&hvc->desc_hw_processing)) {
+		hvc->issue_synchronize = true;
+		sync_needed = true;
+	}
+	spin_unlock(&hvc->vc.lock);
+
+	if (sync_needed)
+		wait_for_completion(&hvc->issue_completion);
+	/*
+	 * At the point, we expect that all remaining descriptors in the ring
+	 * for the channel should be all processing done.
+	 */
+	WARN_ONCE(!list_empty(&hvc->desc_hw_processing),
+		  "Desc pending still in list desc_hw_processing\n");
+
+	/* Free all descriptors in list desc_completed */
+	vchan_synchronize(&hvc->vc);
+
+	WARN_ONCE(!list_empty(&hvc->vc.desc_completed),
+		  "Desc pending still in list desc_completed\n");
+}
+
+static int mtk_hsdma_terminate_all(struct dma_chan *c)
+{
+	/*
+	 * Free pending descriptors not processed yet by hardware that have
+	 * previously been submitted to the channel.
+	 */
+	mtk_hsdma_free_inactive_desc(c);
+
+	/*
+	 * However, the DMA engine doesn't provide any way to stop these
+	 * descriptors being processed currently by hardware. The only way is
+	 * to just waiting until these descriptors are all processed completely
+	 * through mtk_hsdma_free_active_desc call.
+	 */
+	mtk_hsdma_free_active_desc(c);
+
+	return 0;
+}
+
+static int mtk_hsdma_alloc_chan_resources(struct dma_chan *c)
+{
+	struct mtk_hsdma_device *hsdma = to_hsdma_dev(c);
+	int err;
+
+	/*
+	 * Since HSDMA has only one PC, the resource for PC is being allocated
+	 * when the first VC is being created and the other VCs would run on
+	 * the same PC.
+	 */
+	if (!refcount_read(&hsdma->pc_refcnt)) {
+		err = mtk_hsdma_alloc_pchan(hsdma, hsdma->pc);
+		if (err)
+			return err;
+		/*
+		 * refcount_inc would complain increment on 0; use-after-free.
+		 * Thus, we need to explicitly set it as 1 initially.
+		 */
+		refcount_set(&hsdma->pc_refcnt, 1);
+	} else {
+		refcount_inc(&hsdma->pc_refcnt);
+	}
+
+	return 0;
+}
+
+static void mtk_hsdma_free_chan_resources(struct dma_chan *c)
+{
+	struct mtk_hsdma_device *hsdma = to_hsdma_dev(c);
+
+	/* Free all descriptors in all lists on the VC */
+	mtk_hsdma_terminate_all(c);
+
+	/* The resource for PC is not freed until all the VCs are destroyed */
+	if (!refcount_dec_and_test(&hsdma->pc_refcnt))
+		return;
+
+	mtk_hsdma_free_pchan(hsdma, hsdma->pc);
+}
+
+static int mtk_hsdma_hw_init(struct mtk_hsdma_device *hsdma)
+{
+	int err;
+
+	pm_runtime_enable(hsdma2dev(hsdma));
+	pm_runtime_get_sync(hsdma2dev(hsdma));
+
+	err = clk_prepare_enable(hsdma->clk);
+	if (err)
+		return err;
+
+	mtk_dma_write(hsdma, MTK_HSDMA_INT_ENABLE, 0);
+	mtk_dma_write(hsdma, MTK_HSDMA_GLO, MTK_HSDMA_GLO_DEFAULT);
+
+	return 0;
+}
+
+static int mtk_hsdma_hw_deinit(struct mtk_hsdma_device *hsdma)
+{
+	mtk_dma_write(hsdma, MTK_HSDMA_GLO, 0);
+
+	clk_disable_unprepare(hsdma->clk);
+
+	pm_runtime_put_sync(hsdma2dev(hsdma));
+	pm_runtime_disable(hsdma2dev(hsdma));
+
+	return 0;
+}
+
+static const struct mtk_hsdma_soc mt7623_soc = {
+	.ddone = BIT(31),
+	.ls0 = BIT(30),
+};
+
+static const struct mtk_hsdma_soc mt7622_soc = {
+	.ddone = BIT(15),
+	.ls0 = BIT(14),
+};
+
+static const struct of_device_id mtk_hsdma_match[] = {
+	{ .compatible = "mediatek,mt7623-hsdma", .data = &mt7623_soc},
+	{ .compatible = "mediatek,mt7622-hsdma", .data = &mt7622_soc},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mtk_hsdma_match);
+
+static int mtk_hsdma_probe(struct platform_device *pdev)
+{
+	struct mtk_hsdma_device *hsdma;
+	struct mtk_hsdma_vchan *vc;
+	struct dma_device *dd;
+	struct resource *res;
+	int i, err;
+
+	hsdma = devm_kzalloc(&pdev->dev, sizeof(*hsdma), GFP_KERNEL);
+	if (!hsdma)
+		return -ENOMEM;
+
+	dd = &hsdma->ddev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	hsdma->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(hsdma->base))
+		return PTR_ERR(hsdma->base);
+
+	hsdma->soc = of_device_get_match_data(&pdev->dev);
+	if (!hsdma->soc) {
+		dev_err(&pdev->dev, "No device match found\n");
+		return -ENODEV;
+	}
+
+	hsdma->clk = devm_clk_get(&pdev->dev, "hsdma");
+	if (IS_ERR(hsdma->clk)) {
+		dev_err(&pdev->dev, "No clock for %s\n",
+			dev_name(&pdev->dev));
+		return PTR_ERR(hsdma->clk);
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "No irq resource for %s\n",
+			dev_name(&pdev->dev));
+		return -EINVAL;
+	}
+	hsdma->irq = res->start;
+
+	refcount_set(&hsdma->pc_refcnt, 0);
+	spin_lock_init(&hsdma->lock);
+
+	dma_cap_set(DMA_MEMCPY, dd->cap_mask);
+
+	dd->copy_align = MTK_HSDMA_ALIGN_SIZE;
+	dd->device_alloc_chan_resources = mtk_hsdma_alloc_chan_resources;
+	dd->device_free_chan_resources = mtk_hsdma_free_chan_resources;
+	dd->device_tx_status = mtk_hsdma_tx_status;
+	dd->device_issue_pending = mtk_hsdma_issue_pending;
+	dd->device_prep_dma_memcpy = mtk_hsdma_prep_dma_memcpy;
+	dd->device_terminate_all = mtk_hsdma_terminate_all;
+	dd->src_addr_widths = MTK_HSDMA_DMA_BUSWIDTHS;
+	dd->dst_addr_widths = MTK_HSDMA_DMA_BUSWIDTHS;
+	dd->directions = BIT(DMA_MEM_TO_MEM);
+	dd->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
+	dd->dev = &pdev->dev;
+	INIT_LIST_HEAD(&dd->channels);
+
+	hsdma->dma_requests = MTK_HSDMA_NR_VCHANS;
+	if (pdev->dev.of_node && of_property_read_u32(pdev->dev.of_node,
+						      "dma-requests",
+						      &hsdma->dma_requests)) {
+		dev_info(&pdev->dev,
+			 "Using %u as missing dma-requests property\n",
+			 MTK_HSDMA_NR_VCHANS);
+	}
+
+	hsdma->pc = devm_kcalloc(&pdev->dev, MTK_HSDMA_NR_MAX_PCHANS,
+				 sizeof(*hsdma->pc), GFP_KERNEL);
+	if (!hsdma->pc)
+		return -ENOMEM;
+
+	hsdma->vc = devm_kcalloc(&pdev->dev, hsdma->dma_requests,
+				 sizeof(*hsdma->vc), GFP_KERNEL);
+	if (!hsdma->vc)
+		return -ENOMEM;
+
+	for (i = 0; i < hsdma->dma_requests; i++) {
+		vc = &hsdma->vc[i];
+		vc->vc.desc_free = mtk_hsdma_vdesc_free;
+		vchan_init(&vc->vc, dd);
+		init_completion(&vc->issue_completion);
+		INIT_LIST_HEAD(&vc->desc_hw_processing);
+	}
+
+	err = dma_async_device_register(dd);
+	if (err)
+		return err;
+
+	err = of_dma_controller_register(pdev->dev.of_node,
+					 of_dma_xlate_by_chan_id, hsdma);
+	if (err) {
+		dev_err(&pdev->dev,
+			"MediaTek HSDMA OF registration failed %d\n", err);
+		goto err_unregister;
+	}
+
+	mtk_hsdma_hw_init(hsdma);
+
+	err = devm_request_irq(&pdev->dev, hsdma->irq,
+			       mtk_hsdma_irq, 0,
+			       dev_name(&pdev->dev), hsdma);
+	if (err) {
+		dev_err(&pdev->dev,
+			"request_irq failed with err %d\n", err);
+		goto err_unregister;
+	}
+
+	platform_set_drvdata(pdev, hsdma);
+
+	dev_info(&pdev->dev, "MediaTek HSDMA driver registered\n");
+
+	return 0;
+
+err_unregister:
+	dma_async_device_unregister(dd);
+
+	return err;
+}
+
+static int mtk_hsdma_remove(struct platform_device *pdev)
+{
+	struct mtk_hsdma_device *hsdma = platform_get_drvdata(pdev);
+	struct mtk_hsdma_vchan *vc;
+	int i;
+
+	/* Kill VC task */
+	for (i = 0; i < hsdma->dma_requests; i++) {
+		vc = &hsdma->vc[i];
+
+		list_del(&vc->vc.chan.device_node);
+		tasklet_kill(&vc->vc.task);
+	}
+
+	/* Disable DMA interrupt */
+	mtk_dma_write(hsdma, MTK_HSDMA_INT_ENABLE, 0);
+
+	/* Waits for any pending IRQ handlers to complete */
+	synchronize_irq(hsdma->irq);
+
+	/* Disable hardware */
+	mtk_hsdma_hw_deinit(hsdma);
+
+	dma_async_device_unregister(&hsdma->ddev);
+	of_dma_controller_free(pdev->dev.of_node);
+
+	return 0;
+}
+
+static struct platform_driver mtk_hsdma_driver = {
+	.probe		= mtk_hsdma_probe,
+	.remove		= mtk_hsdma_remove,
+	.driver = {
+		.name		= KBUILD_MODNAME,
+		.of_match_table	= mtk_hsdma_match,
+	},
+};
+module_platform_driver(mtk_hsdma_driver);
+
+MODULE_DESCRIPTION("MediaTek High-Speed DMA Controller Driver");
+MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
+MODULE_LICENSE("GPL v2");