[PATCH v5 0/2] dmaengine: avalon: Intel Avalon-MM DMA Interface forPCIe

[PATCH v5 0/2] dmaengine: avalon: Intel Avalon-MM DMA Interface forPCIe

[Alexander Gordeev]

This series is against v5.4-rc6

Patch 1. Introduces "avalon-dma" driver that conforms to the standard
"dmaengine" model;

Patch 2. The existing "dmatest" is not meant for DMA_SLAVE type of
transfers needed by "avalon-dma" driver. Instead, custom "avalon-test"
was used to debug and stress "avalon-dma". In fact, the methology used
for testing is pretty much generic:

  - DMA to/from the remote device (memory) - oneshot or multiple times;
  - continuously run cuncurrent threads DMAing to/from the remote device;
  - using IOCTL to DMA data to/from user level;

Such functionality could be very useful for bringing up custom embedded
devices, i.e sensors, displays etc.

With some effort "avalon-test" could even be merged into the existing
"dmatest" or turned into a tool for testing any "dmaengine" compatible
driver that does not need any custom hardware specifics to initiate DMA
transfers.

I am not certain that "avalon-test" in its current form is the best way
to proceed and thus marking patch 2 as RFC. It depends on "avalon-dma",
but the two drivers are not necessary to go along.


Changes since v4:
- kbuild test robot reported issues fixed;

Changes since v3 ("avalon-test" only):
- BUG_ONs, WARN_ONs, dev_dbgs removed goto labels renamed;
- kernel configuration options removed in favour of module parameters;
- fail paths reworked to avoid resource leaks uninitialized data crashes;
- invalid parameter checks reworked;

Changes since v2 ("avalon-dma" only):
- avalon_dma_register() return value bug fixed;
- device_prep_slave_sg() does not crash dmaengine_prep_slave_single();
- kernel configuration options removed in favour of module parameters;
- BUG_ONs, WARN_ONs, dev_dbgs removed goto labels renamed;
- polling loop in interrupt handler commented;
- cpu_relax() added to polling loop in interrupt handler;

Changes since v1:
- "avalon-dma" converted to "dmaengine" model;
- "avalon-drv" renamed to "avalon-test";

The Avalon-MM DMA Interface for PCIe is a design used in hard IPs for
Intel Arria, Cyclone or Stratix FPGAs. It transfers data between on-chip
memory and system memory.

Testing was done using a custom FPGA build with Arria 10 FPGA streaming
data to target device RAM:

  +----------+    +----------+    +----------+        +----------+
  | NIOS CPU |<-->|   RAM    |<-->|  Avalon  |<-PCIe->| Host CPU |
  +----------+    +----------+    +----------+        +----------+

The data integrity was ensured by examining target device RAM contents
(a) from host CPU (indirectly - checking data DMAed to/from the system)
and (b) from NIOS CPU that has direct access to the device RAM.

A companion tool using "avalon-test" IOCTL commands was used to DMA files:
https://github.com/a-gordeev/avalon-tool.git

CC: dmaengine@vger.kernel.org

Alexander Gordeev (2):
  dmaengine: avalon-dma: Intel Avalon-MM DMA Interface for PCIe
  dmaengine: avalon-test: Intel Avalon-MM DMA Interface for PCIe test

 drivers/dma/Kconfig                     |   3 +
 drivers/dma/Makefile                    |   2 +
 drivers/dma/avalon-test/Kconfig         |  12 +
 drivers/dma/avalon-test/Makefile        |  14 +
 drivers/dma/avalon-test/avalon-dev.c    | 108 +++++
 drivers/dma/avalon-test/avalon-dev.h    |  33 ++
 drivers/dma/avalon-test/avalon-ioctl.c  | 101 +++++
 drivers/dma/avalon-test/avalon-ioctl.h  |  13 +
 drivers/dma/avalon-test/avalon-mmap.c   |  74 +++
 drivers/dma/avalon-test/avalon-mmap.h   |  13 +
 drivers/dma/avalon-test/avalon-sg-buf.c | 132 ++++++
 drivers/dma/avalon-test/avalon-sg-buf.h |  27 ++
 drivers/dma/avalon-test/avalon-xfer.c   | 575 ++++++++++++++++++++++++
 drivers/dma/avalon-test/avalon-xfer.h   |  29 ++
 drivers/dma/avalon/Kconfig              |  15 +
 drivers/dma/avalon/Makefile             |  12 +
 drivers/dma/avalon/avalon-core.c        | 477 ++++++++++++++++++++
 drivers/dma/avalon/avalon-core.h        |  92 ++++
 drivers/dma/avalon/avalon-hw.c          | 187 ++++++++
 drivers/dma/avalon/avalon-hw.h          |  86 ++++
 drivers/dma/avalon/avalon-pci.c         | 145 ++++++
 include/uapi/linux/avalon-ioctl.h       |  34 ++
 22 files changed, 2184 insertions(+)
 create mode 100644 drivers/dma/avalon-test/Kconfig
 create mode 100644 drivers/dma/avalon-test/Makefile
 create mode 100644 drivers/dma/avalon-test/avalon-dev.c
 create mode 100644 drivers/dma/avalon-test/avalon-dev.h
 create mode 100644 drivers/dma/avalon-test/avalon-ioctl.c
 create mode 100644 drivers/dma/avalon-test/avalon-ioctl.h
 create mode 100644 drivers/dma/avalon-test/avalon-mmap.c
 create mode 100644 drivers/dma/avalon-test/avalon-mmap.h
 create mode 100644 drivers/dma/avalon-test/avalon-sg-buf.c
 create mode 100644 drivers/dma/avalon-test/avalon-sg-buf.h
 create mode 100644 drivers/dma/avalon-test/avalon-xfer.c
 create mode 100644 drivers/dma/avalon-test/avalon-xfer.h
 create mode 100644 drivers/dma/avalon/Kconfig
 create mode 100644 drivers/dma/avalon/Makefile
 create mode 100644 drivers/dma/avalon/avalon-core.c
 create mode 100644 drivers/dma/avalon/avalon-core.h
 create mode 100644 drivers/dma/avalon/avalon-hw.c
 create mode 100644 drivers/dma/avalon/avalon-hw.h
 create mode 100644 drivers/dma/avalon/avalon-pci.c
 create mode 100644 include/uapi/linux/avalon-ioctl.h


base-commit: a99d8080aaf358d5d23581244e5da23b35e340b9
-- 
2.24.0

[PATCH v5 1/2] dmaengine: avalon-dma: Intel Avalon-MM DMA Interface for PCIe

[Alexander Gordeev]

Support Avalon-MM DMA Interface for PCIe used in hard IPs for
Intel Arria, Cyclone or Stratix FPGAs.

CC: dmaengine@vger.kernel.org

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Alexander Gordeev <a.gordeev.box@gmail.com>
---
 drivers/dma/Kconfig              |   2 +
 drivers/dma/Makefile             |   1 +
 drivers/dma/avalon/Kconfig       |  15 +
 drivers/dma/avalon/Makefile      |  12 +
 drivers/dma/avalon/avalon-core.c | 477 +++++++++++++++++++++++++++++++
 drivers/dma/avalon/avalon-core.h |  92 ++++++
 drivers/dma/avalon/avalon-hw.c   | 187 ++++++++++++
 drivers/dma/avalon/avalon-hw.h   |  86 ++++++
 drivers/dma/avalon/avalon-pci.c  | 145 ++++++++++
 9 files changed, 1017 insertions(+)
 create mode 100644 drivers/dma/avalon/Kconfig
 create mode 100644 drivers/dma/avalon/Makefile
 create mode 100644 drivers/dma/avalon/avalon-core.c
 create mode 100644 drivers/dma/avalon/avalon-core.h
 create mode 100644 drivers/dma/avalon/avalon-hw.c
 create mode 100644 drivers/dma/avalon/avalon-hw.h
 create mode 100644 drivers/dma/avalon/avalon-pci.c

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 7af874b69ffb..f6f43480a4a4 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -669,6 +669,8 @@ source "drivers/dma/sh/Kconfig"
 
 source "drivers/dma/ti/Kconfig"
 
+source "drivers/dma/avalon/Kconfig"
+
 # clients
 comment "DMA Clients"
 	depends on DMA_ENGINE
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index f5ce8665e944..fd7e11417b73 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_UNIPHIER_MDMAC) += uniphier-mdmac.o
 obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
 obj-$(CONFIG_ZX_DMA) += zx_dma.o
 obj-$(CONFIG_ST_FDMA) += st_fdma.o
+obj-$(CONFIG_AVALON_DMA) += avalon/
 
 obj-y += mediatek/
 obj-y += qcom/
diff --git a/drivers/dma/avalon/Kconfig b/drivers/dma/avalon/Kconfig
new file mode 100644
index 000000000000..b8cbb6fc04db
--- /dev/null
+++ b/drivers/dma/avalon/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2019, The Linux Foundation. All rights reserved.
+# Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+#
+# Avalon DMA engine
+#
+config AVALON_DMA
+	tristate "Intel Avalon-MM DMA Interface for PCIe"
+	depends on PCI
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  This selects a driver for Avalon-MM DMA Interface for PCIe
+	  hard IP block used in Intel Arria, Cyclone or Stratix FPGAs.
diff --git a/drivers/dma/avalon/Makefile b/drivers/dma/avalon/Makefile
new file mode 100644
index 000000000000..483a31f0a289
--- /dev/null
+++ b/drivers/dma/avalon/Makefile
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2019, The Linux Foundation. All rights reserved.
+# Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+#
+# Avalon DMA engine
+#
+obj-$(CONFIG_AVALON_DMA)	+= avalon-dma.o
+
+avalon-dma-objs			:= avalon-hw.o \
+				   avalon-core.o \
+				   avalon-pci.o
diff --git a/drivers/dma/avalon/avalon-core.c b/drivers/dma/avalon/avalon-core.c
new file mode 100644
index 000000000000..eff2c4901f51
--- /dev/null
+++ b/drivers/dma/avalon/avalon-core.c
@@ -0,0 +1,477 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA engine
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+
+#include "avalon-hw.h"
+#include "avalon-core.h"
+
+#define INTERRUPT_NAME		"avalon_dma"
+
+static unsigned int dma_mask_width = 64;
+module_param(dma_mask_width, uint, 0644);
+MODULE_PARM_DESC(dma_mask_width, "Avalon DMA bitmask width (default: 64)");
+
+unsigned long ctrl_base;
+module_param(ctrl_base, ulong, 0644);
+MODULE_PARM_DESC(ctrl_base, "Avalon DMA controller base (default: 0)");
+
+static unsigned int rd_ep_dst_lo = 0x80000000;
+module_param(rd_ep_dst_lo, uint, 0644);
+MODULE_PARM_DESC(rd_ep_dst_lo,
+		 "Read status and desc table low (default: 0x80000000)");
+
+static unsigned int rd_ep_dst_hi = 0;
+module_param(rd_ep_dst_hi, uint, 0644);
+MODULE_PARM_DESC(rd_ep_dst_hi,
+		 "Read status and desc table hi (default: 0)");
+
+static unsigned int wr_ep_dst_lo = 0x80002000;
+module_param(wr_ep_dst_lo, uint, 0644);
+MODULE_PARM_DESC(wr_ep_dst_lo,
+		 "Write status and desc table low (default: 0x80002000)");
+
+static unsigned int wr_ep_dst_hi = 0;
+module_param(wr_ep_dst_hi, uint, 0644);
+MODULE_PARM_DESC(wr_ep_dst_hi,
+		 "Write status and desc table hi (default: 0)");
+
+static int setup_dma_descs(struct dma_desc *dma_descs,
+			   struct avalon_dma_desc *desc)
+{
+	unsigned int seg_stop;
+	unsigned int seg_set;
+	int ret;
+
+	ret = setup_descs_sg(dma_descs, 0,
+			     desc->direction,
+			     desc->dev_addr,
+			     desc->seg, desc->nr_segs,
+			     desc->seg_curr, desc->seg_off,
+			     &seg_stop, &seg_set);
+	if (ret < 0)
+		return ret;
+
+	if (seg_stop == desc->seg_curr) {
+		desc->seg_off += seg_set;
+	} else {
+		desc->seg_curr = seg_stop;
+		desc->seg_off = seg_set;
+	}
+
+	return ret;
+}
+
+static int start_dma_xfer(struct avalon_dma_hw *hw,
+			  struct avalon_dma_desc *desc)
+{
+	size_t ctrl_off;
+	struct __dma_desc_table *__table;
+	struct dma_desc_table *table;
+	u32 rc_src_hi, rc_src_lo;
+	u32 ep_dst_lo, ep_dst_hi;
+	int last_id, *__last_id;
+	int nr_descs;
+
+	if (desc->direction == DMA_MEM_TO_DEV) {
+		__table = &hw->dma_desc_table_rd;
+
+		ctrl_off = AVALON_DMA_RD_CTRL_OFFSET;
+
+		ep_dst_hi = rd_ep_dst_hi;
+		ep_dst_lo = rd_ep_dst_lo;
+
+		__last_id = &hw->h2d_last_id;
+	} else if (desc->direction == DMA_DEV_TO_MEM) {
+		__table = &hw->dma_desc_table_wr;
+
+		ctrl_off = AVALON_DMA_WR_CTRL_OFFSET;
+
+		ep_dst_hi = wr_ep_dst_hi;
+		ep_dst_lo = wr_ep_dst_lo;
+
+		__last_id = &hw->d2h_last_id;
+	} else {
+		return -EINVAL;
+	}
+
+	table = __table->cpu_addr;
+	memset(&table->flags, 0, sizeof(table->flags));
+
+	nr_descs = setup_dma_descs(table->descs, desc);
+	if (nr_descs < 0)
+		return nr_descs;
+
+	last_id = nr_descs - 1;
+	*__last_id = last_id;
+
+	rc_src_hi = (u32)(__table->dma_addr >> 32);
+	rc_src_lo = (u32)__table->dma_addr;
+
+	start_xfer(hw->regs, ctrl_off,
+		   rc_src_hi, rc_src_lo,
+		   ep_dst_hi, ep_dst_lo,
+		   last_id);
+
+	return 0;
+}
+
+static bool is_desc_complete(struct avalon_dma_desc *desc)
+{
+	if (desc->seg_curr < (desc->nr_segs - 1))
+		return false;
+
+	if (desc->seg_off < desc->seg[desc->seg_curr].dma_len)
+		return false;
+
+	return true;
+}
+
+static irqreturn_t avalon_dma_interrupt(int irq, void *dev_id)
+{
+	struct avalon_dma *adma = (struct avalon_dma *)dev_id;
+	struct avalon_dma_chan *chan = &adma->chan;
+	struct avalon_dma_hw *hw = &chan->hw;
+	__le32 *rd_flags = hw->dma_desc_table_rd.cpu_addr->flags;
+	__le32 *wr_flags = hw->dma_desc_table_wr.cpu_addr->flags;
+	struct avalon_dma_desc *desc;
+	struct virt_dma_desc *vdesc;
+	bool rd_done;
+	bool wr_done;
+
+	spin_lock(&chan->vchan.lock);
+
+	rd_done = (hw->h2d_last_id < 0);
+	wr_done = (hw->d2h_last_id < 0);
+
+	if (rd_done && wr_done) {
+		spin_unlock(&chan->vchan.lock);
+		return IRQ_NONE;
+	}
+
+	/*
+	 * The Intel documentation claims "The Descriptor Controller
+	 * writes a 1 to the done bit of the status DWORD to indicate
+	 * successful completion. The Descriptor Controller also sends
+	 * an MSI interrupt for the final descriptor. After receiving
+	 * this MSI, host software can poll the done bit to determine
+	 * status."
+	 *
+	 * The above could be read like MSI interrupt might be delivered
+	 * before the corresponding done bit is set. But in reality it
+	 * does not happen at all (or happens really rare). So put here
+	 * the done bit polling, just in case.
+	 */
+	do {
+		if (!rd_done && rd_flags[hw->h2d_last_id])
+			rd_done = true;
+		if (!wr_done && wr_flags[hw->d2h_last_id])
+			wr_done = true;
+		cpu_relax();
+	} while (!rd_done || !wr_done);
+
+	hw->h2d_last_id = -1;
+	hw->d2h_last_id = -1;
+
+	desc = chan->active_desc;
+
+	if (is_desc_complete(desc)) {
+		list_del(&desc->vdesc.node);
+		vchan_cookie_complete(&desc->vdesc);
+
+		desc->direction = DMA_NONE;
+
+		vdesc = vchan_next_desc(&chan->vchan);
+		if (vdesc) {
+			desc = to_avalon_dma_desc(vdesc);
+			chan->active_desc = desc;
+		} else {
+			chan->active_desc = NULL;
+		}
+	}
+
+	if (chan->active_desc)
+		start_dma_xfer(hw, desc);
+
+	spin_unlock(&chan->vchan.lock);
+
+	return IRQ_HANDLED;
+}
+
+static int avalon_dma_terminate_all(struct dma_chan *dma_chan)
+{
+	struct virt_dma_chan *vchan = to_virt_chan(dma_chan);
+
+	vchan_free_chan_resources(vchan);
+
+	return 0;
+}
+
+static void avalon_dma_synchronize(struct dma_chan *dma_chan)
+{
+	struct virt_dma_chan *vchan = to_virt_chan(dma_chan);
+
+	vchan_synchronize(vchan);
+}
+
+static int avalon_dma_init(struct avalon_dma *adma,
+			   struct device *dev,
+			   void __iomem *regs,
+			   unsigned int irq)
+{
+	struct avalon_dma_chan *chan = &adma->chan;
+	struct avalon_dma_hw *hw = &chan->hw;
+	int ret;
+
+	adma->dev		= dev;
+	adma->irq		= irq;
+
+	chan->active_desc	= NULL;
+
+	hw->regs		= regs;
+	hw->h2d_last_id		= -1;
+	hw->d2h_last_id		= -1;
+
+	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(dma_mask_width));
+	if (ret)
+		return ret;
+
+	hw->dma_desc_table_rd.cpu_addr = dma_alloc_coherent(
+		dev,
+		sizeof(struct dma_desc_table),
+		&hw->dma_desc_table_rd.dma_addr,
+		GFP_KERNEL);
+	if (!hw->dma_desc_table_rd.cpu_addr)
+		return -ENOMEM;
+
+	hw->dma_desc_table_wr.cpu_addr = dma_alloc_coherent(
+		dev,
+		sizeof(struct dma_desc_table),
+		&hw->dma_desc_table_wr.dma_addr,
+		GFP_KERNEL);
+	if (!hw->dma_desc_table_wr.cpu_addr) {
+		ret = -ENOMEM;
+		goto free_table_rd;
+	}
+
+	ret = request_irq(irq, avalon_dma_interrupt, IRQF_SHARED,
+			  INTERRUPT_NAME, adma);
+	if (ret)
+		goto free_table_wr;
+
+	return 0;
+
+free_table_wr:
+	dma_free_coherent(
+		dev,
+		sizeof(struct dma_desc_table),
+		hw->dma_desc_table_wr.cpu_addr,
+		hw->dma_desc_table_wr.dma_addr);
+
+free_table_rd:
+	dma_free_coherent(
+		dev,
+		sizeof(struct dma_desc_table),
+		hw->dma_desc_table_rd.cpu_addr,
+		hw->dma_desc_table_rd.dma_addr);
+
+	return ret;
+}
+
+static void avalon_dma_term(struct avalon_dma *adma)
+{
+	struct avalon_dma_chan *chan = &adma->chan;
+	struct avalon_dma_hw *hw = &chan->hw;
+	struct device *dev = adma->dev;
+
+	free_irq(adma->irq, adma);
+
+	dma_free_coherent(
+		dev,
+		sizeof(struct dma_desc_table),
+		hw->dma_desc_table_rd.cpu_addr,
+		hw->dma_desc_table_rd.dma_addr);
+
+	dma_free_coherent(
+		dev,
+		sizeof(struct dma_desc_table),
+		hw->dma_desc_table_wr.cpu_addr,
+		hw->dma_desc_table_wr.dma_addr);
+}
+
+static int avalon_dma_device_config(struct dma_chan *dma_chan,
+				    struct dma_slave_config *config)
+{
+	struct avalon_dma_chan *chan = to_avalon_dma_chan(dma_chan);
+
+	if (!IS_ALIGNED(config->src_addr, sizeof(u32)) ||
+	    !IS_ALIGNED(config->dst_addr, sizeof(u32)))
+		return -EINVAL;
+
+	chan->src_addr = config->src_addr;
+	chan->dst_addr = config->dst_addr;
+
+	return 0;
+}
+
+static struct dma_async_tx_descriptor *
+avalon_dma_prep_slave_sg(struct dma_chan *dma_chan,
+			 struct scatterlist *sg, unsigned int sg_len,
+			 enum dma_transfer_direction direction,
+			 unsigned long flags, void *context)
+{
+	struct avalon_dma_chan *chan = to_avalon_dma_chan(dma_chan);
+	struct avalon_dma_desc *desc;
+	dma_addr_t dev_addr;
+	int i;
+
+	if (direction == DMA_MEM_TO_DEV)
+		dev_addr = chan->dst_addr;
+	else if (direction == DMA_DEV_TO_MEM)
+		dev_addr = chan->src_addr;
+	else
+		return NULL;
+
+	desc = kzalloc(struct_size(desc, seg, sg_len), GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	desc->direction = direction;
+	desc->dev_addr	= dev_addr;
+	desc->seg_curr	= 0;
+	desc->seg_off	= 0;
+	desc->nr_segs	= sg_len;
+
+	for (i = 0; i < sg_len; i++) {
+		struct dma_segment *seg = &desc->seg[i];
+		dma_addr_t dma_addr = sg_dma_address(sg);
+		unsigned int dma_len = sg_dma_len(sg);
+
+		if (!IS_ALIGNED(dma_addr, sizeof(u32)) ||
+		    !IS_ALIGNED(dma_len, sizeof(u32)))
+			return NULL;
+
+		seg->dma_addr = dma_addr;
+		seg->dma_len = dma_len;
+
+		sg = sg_next(sg);
+	}
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static void avalon_dma_issue_pending(struct dma_chan *dma_chan)
+{
+	struct avalon_dma_chan *chan = to_avalon_dma_chan(dma_chan);
+	struct avalon_dma_hw *hw = &chan->hw;
+	struct avalon_dma_desc *desc;
+	struct virt_dma_desc *vdesc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+
+	if (!vchan_issue_pending(&chan->vchan))
+		goto out;
+
+	/*
+	 * Do nothing if a DMA transmission is currently active.
+	 * BOTH read and write status must be checked here!
+	 */
+	if (hw->d2h_last_id < 0 && hw->h2d_last_id < 0) {
+		if (chan->active_desc)
+			goto out;
+
+		vdesc = vchan_next_desc(&chan->vchan);
+		desc = to_avalon_dma_desc(vdesc);
+		chan->active_desc = desc;
+
+		if (start_dma_xfer(hw, desc))
+			goto out;
+	}
+
+out:
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+}
+
+static void avalon_dma_desc_free(struct virt_dma_desc *vdesc)
+{
+	struct avalon_dma_desc *desc = to_avalon_dma_desc(vdesc);
+
+	kfree(desc);
+}
+
+struct avalon_dma *avalon_dma_register(struct device *dev,
+				       void __iomem *regs,
+				       unsigned int irq)
+{
+	struct avalon_dma *adma;
+	struct avalon_dma_chan *chan;
+	struct dma_device *dma_dev;
+	int ret;
+
+	adma = kzalloc(sizeof(*adma), GFP_KERNEL);
+	if (!adma)
+		return ERR_PTR(-ENOMEM);
+
+	ret = avalon_dma_init(adma, dev, regs, irq);
+	if (ret)
+		goto err;
+
+	dev->dma_parms = &adma->dma_parms;
+	dma_set_max_seg_size(dev, UINT_MAX);
+
+	dma_dev = &adma->dma_dev;
+	dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
+
+	dma_dev->device_tx_status = dma_cookie_status;
+	dma_dev->device_prep_slave_sg = avalon_dma_prep_slave_sg;
+	dma_dev->device_issue_pending = avalon_dma_issue_pending;
+	dma_dev->device_terminate_all = avalon_dma_terminate_all;
+	dma_dev->device_synchronize = avalon_dma_synchronize;
+	dma_dev->device_config = avalon_dma_device_config;
+
+	dma_dev->dev = dev;
+	dma_dev->chancnt = 1;
+
+	dma_dev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	dma_dev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	dma_dev->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
+
+	INIT_LIST_HEAD(&dma_dev->channels);
+
+	chan = &adma->chan;
+	chan->src_addr = -1;
+	chan->dst_addr = -1;
+	chan->vchan.desc_free = avalon_dma_desc_free;
+
+	vchan_init(&chan->vchan, dma_dev);
+
+	ret = dma_async_device_register(dma_dev);
+	if (ret)
+		goto err;
+
+	return adma;
+
+err:
+	kfree(adma);
+
+	return ERR_PTR(ret);
+}
+
+void avalon_dma_unregister(struct avalon_dma *adma)
+{
+	dmaengine_terminate_sync(&adma->chan.vchan.chan);
+	dma_async_device_unregister(&adma->dma_dev);
+
+	avalon_dma_term(adma);
+
+	kfree(adma);
+}
diff --git a/drivers/dma/avalon/avalon-core.h b/drivers/dma/avalon/avalon-core.h
new file mode 100644
index 000000000000..9a03212e2822
--- /dev/null
+++ b/drivers/dma/avalon/avalon-core.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA engine
+ */
+#ifndef __AVALON_CORE_H__
+#define __AVALON_CORE_H__
+
+#include <linux/interrupt.h>
+
+#include "../virt-dma.h"
+
+#include "avalon-hw.h"
+
+struct avalon_dma_desc {
+	struct virt_dma_desc	vdesc;
+
+	enum dma_transfer_direction	direction;
+
+	dma_addr_t		dev_addr;
+
+	unsigned int		seg_curr;
+	unsigned int		seg_off;
+
+	unsigned int		nr_segs;
+	struct dma_segment	seg[];
+};
+
+struct avalon_dma_hw {
+	struct __dma_desc_table {
+		struct dma_desc_table *cpu_addr;
+		dma_addr_t dma_addr;
+	} dma_desc_table_rd, dma_desc_table_wr;
+
+	int			h2d_last_id;
+	int			d2h_last_id;
+
+	void __iomem		*regs;
+};
+
+struct avalon_dma_chan {
+	struct virt_dma_chan	vchan;
+
+	dma_addr_t		src_addr;
+	dma_addr_t		dst_addr;
+
+	struct avalon_dma_hw	hw;
+
+	struct avalon_dma_desc	*active_desc;
+};
+
+struct avalon_dma {
+	struct device		*dev;
+	unsigned int		irq;
+
+	struct avalon_dma_chan	chan;
+	struct dma_device	dma_dev;
+	struct device_dma_parameters dma_parms;
+};
+
+static inline
+struct avalon_dma_chan *to_avalon_dma_chan(struct dma_chan *dma_chan)
+{
+	return container_of(dma_chan, struct avalon_dma_chan, vchan.chan);
+}
+
+static inline
+struct avalon_dma_desc *to_avalon_dma_desc(struct virt_dma_desc *vdesc)
+{
+	return container_of(vdesc, struct avalon_dma_desc, vdesc);
+}
+
+static inline
+struct avalon_dma *chan_to_avalon_dma(struct avalon_dma_chan *chan)
+{
+	return container_of(chan, struct avalon_dma, chan);
+}
+
+static inline
+__iomem void *__iomem avalon_dma_mmio(struct avalon_dma *adma)
+{
+	return adma->chan.hw.regs;
+}
+
+struct avalon_dma *avalon_dma_register(struct device *dev,
+				       void __iomem *regs,
+				       unsigned int irq);
+void avalon_dma_unregister(struct avalon_dma *adma);
+
+#endif
diff --git a/drivers/dma/avalon/avalon-hw.c b/drivers/dma/avalon/avalon-hw.c
new file mode 100644
index 000000000000..447e4ae381d6
--- /dev/null
+++ b/drivers/dma/avalon/avalon-hw.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA engine
+ */
+#include <linux/kernel.h>
+
+#include "avalon-hw.h"
+
+#define DMA_DESC_MAX		AVALON_DMA_DESC_NUM
+
+static void setup_desc(struct dma_desc *desc, u32 desc_id,
+		       u64 dest, u64 src, u32 size)
+{
+	desc->src_lo = cpu_to_le32(src & 0xfffffffful);
+	desc->src_hi = cpu_to_le32((src >> 32));
+	desc->dst_lo = cpu_to_le32(dest & 0xfffffffful);
+	desc->dst_hi = cpu_to_le32((dest >> 32));
+	desc->ctl_dma_len = cpu_to_le32((size >> 2) | (desc_id << 18));
+	desc->reserved[0] = cpu_to_le32(0x0);
+	desc->reserved[1] = cpu_to_le32(0x0);
+	desc->reserved[2] = cpu_to_le32(0x0);
+}
+
+static
+int setup_descs(struct dma_desc *descs, unsigned int desc_id,
+		enum dma_transfer_direction direction,
+		dma_addr_t dev_addr, dma_addr_t host_addr, unsigned int len,
+		unsigned int *_set)
+{
+	int nr_descs = 0;
+	unsigned int set = 0;
+	dma_addr_t src;
+	dma_addr_t dest;
+
+	if (desc_id >= DMA_DESC_MAX)
+		return -EINVAL;
+
+	if (direction == DMA_MEM_TO_DEV) {
+		src = host_addr;
+		dest = dev_addr;
+	} else {
+		src = dev_addr;
+		dest = host_addr;
+	}
+
+	while (len) {
+		unsigned int xfer_len = min_t(unsigned int, len, AVALON_DMA_MAX_TANSFER_SIZE);
+
+		setup_desc(descs, desc_id, dest, src, xfer_len);
+
+		set += xfer_len;
+
+		nr_descs++;
+		if (nr_descs >= DMA_DESC_MAX)
+			break;
+
+		desc_id++;
+		if (desc_id >= DMA_DESC_MAX)
+			break;
+
+		descs++;
+
+		dest += xfer_len;
+		src += xfer_len;
+
+		len -= xfer_len;
+	}
+
+	*_set = set;
+
+	return nr_descs;
+}
+
+int setup_descs_sg(struct dma_desc *descs, unsigned int desc_id,
+		   enum dma_transfer_direction direction,
+		   dma_addr_t dev_addr,
+		   struct dma_segment *seg, unsigned int nr_segs,
+		   unsigned int seg_start, unsigned int seg_off,
+		   unsigned int *seg_stop, unsigned int *seg_set)
+{
+	unsigned int set = -1;
+	int nr_descs = 0;
+	int ret;
+	int i;
+
+	if (seg_start >= nr_segs)
+		return -EINVAL;
+	if ((direction != DMA_MEM_TO_DEV) && (direction != DMA_DEV_TO_MEM))
+		return -EINVAL;
+
+	/*
+	 * Skip all SGEs that have been fully transmitted.
+	 */
+	for (i = 0; i < seg_start; i++)
+		dev_addr += seg[i].dma_len;
+
+	/*
+	 * Skip the current SGE if it has been fully transmitted.
+	 */
+	if (seg[i].dma_len == seg_off) {
+		dev_addr += seg_off;
+		seg_off = 0;
+		i++;
+	}
+
+	/*
+	 * Setup as many SGEs as the controller is able to transmit.
+	 */
+	for (; i < nr_segs; i++) {
+		dma_addr_t dma_addr = seg[i].dma_addr;
+		unsigned int dma_len = seg[i].dma_len;
+
+		/*
+		 * The offset can not be longer than the SGE length.
+		 */
+		if (dma_len < seg_off)
+			return -EINVAL;
+
+		if (seg_off) {
+			dev_addr += seg_off;
+			dma_addr += seg_off;
+			dma_len -= seg_off;
+
+			seg_off = 0;
+		}
+
+		ret = setup_descs(descs, desc_id, direction,
+				  dev_addr, dma_addr, dma_len, &set);
+		if (ret < 0)
+			return ret;
+
+		if ((desc_id + ret > DMA_DESC_MAX) ||
+		    (nr_descs + ret > DMA_DESC_MAX))
+			return -EINVAL;
+
+		nr_descs += ret;
+		desc_id += ret;
+
+		/*
+		 * Stop when descriptor table entries are exhausted.
+		 */
+		if (desc_id == DMA_DESC_MAX)
+			break;
+
+		/*
+		 * The descriptor table still has free entries, thus
+		 * the current SGE should have fit.
+		 */
+		if (dma_len != set)
+			return -EINVAL;
+
+		if (i >= nr_segs - 1)
+			break;
+
+		descs += ret;
+		dev_addr += dma_len;
+	}
+
+	/*
+	 * Remember the SGE that next transmission should be started from.
+	 */
+	if (nr_descs) {
+		*seg_stop = i;
+		*seg_set = set;
+	} else {
+		*seg_stop = seg_start;
+		*seg_set = seg_off;
+	}
+
+	return nr_descs;
+}
+
+void start_xfer(void __iomem *base, size_t ctrl_off,
+		u32 rc_src_hi, u32 rc_src_lo,
+		u32 ep_dst_hi, u32 ep_dst_lo,
+		int last_id)
+{
+	av_write32(rc_src_hi, base, ctrl_off, rc_src_hi);
+	av_write32(rc_src_lo, base, ctrl_off, rc_src_lo);
+	av_write32(ep_dst_hi, base, ctrl_off, ep_dst_hi);
+	av_write32(ep_dst_lo, base, ctrl_off, ep_dst_lo);
+	av_write32(last_id, base, ctrl_off, table_size);
+	av_write32(last_id, base, ctrl_off, last_ptr);
+}
diff --git a/drivers/dma/avalon/avalon-hw.h b/drivers/dma/avalon/avalon-hw.h
new file mode 100644
index 000000000000..35c4fa3c05d3
--- /dev/null
+++ b/drivers/dma/avalon/avalon-hw.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA engine
+ */
+#ifndef __AVALON_HW_H__
+#define __AVALON_HW_H__
+
+#include <linux/io.h>
+#include <linux/dmaengine.h>
+
+#define AVALON_DMA_DESC_NUM		128
+
+#define AVALON_DMA_FIXUP_SIZE		0x100
+#define AVALON_DMA_MAX_TANSFER_SIZE	(0x100000 - AVALON_DMA_FIXUP_SIZE)
+
+#define AVALON_DMA_RD_CTRL_OFFSET	0x0
+#define AVALON_DMA_WR_CTRL_OFFSET	0x100
+
+extern unsigned long ctrl_base;
+
+static inline
+u32 __av_read32(void __iomem *base, size_t ctrl_off, size_t reg_off)
+{
+	size_t offset = ctrl_base + ctrl_off + reg_off;
+
+	return ioread32(base + offset);
+}
+
+static inline
+void __av_write32(u32 val,
+		  void __iomem *base, size_t ctrl_off, size_t reg_off)
+{
+	size_t offset = ctrl_base + ctrl_off + reg_off;
+
+	iowrite32(val, base + offset);
+}
+
+#define av_read32(b, o, r) \
+	__av_read32(b, o, offsetof(struct dma_ctrl, r))
+#define av_write32(v, b, o, r) \
+	__av_write32(v, b, o, offsetof(struct dma_ctrl, r))
+
+struct dma_ctrl {
+	__le32 rc_src_lo;
+	__le32 rc_src_hi;
+	__le32 ep_dst_lo;
+	__le32 ep_dst_hi;
+	__le32 last_ptr;
+	__le32 table_size;
+	__le32 control;
+} __packed;
+
+struct dma_desc {
+	__le32 src_lo;
+	__le32 src_hi;
+	__le32 dst_lo;
+	__le32 dst_hi;
+	__le32 ctl_dma_len;
+	__le32 reserved[3];
+} __packed;
+
+struct dma_desc_table {
+	__le32 flags[AVALON_DMA_DESC_NUM];
+	struct dma_desc descs[AVALON_DMA_DESC_NUM];
+} __packed;
+
+struct dma_segment {
+	dma_addr_t	dma_addr;
+	unsigned int	dma_len;
+};
+
+int setup_descs_sg(struct dma_desc *descs, unsigned int desc_id,
+		   enum dma_transfer_direction direction,
+		   dma_addr_t dev_addr,
+		   struct dma_segment *seg, unsigned int nr_segs,
+		   unsigned int seg_start, unsigned int sg_off,
+		   unsigned int *seg_stop, unsigned int *seg_set);
+
+void start_xfer(void __iomem *base, size_t ctrl_off,
+		u32 rc_src_hi, u32 rc_src_lo,
+		u32 ep_dst_hi, u32 ep_dst_lo,
+		int last_id);
+#endif
diff --git a/drivers/dma/avalon/avalon-pci.c b/drivers/dma/avalon/avalon-pci.c
new file mode 100644
index 000000000000..701ecb419097
--- /dev/null
+++ b/drivers/dma/avalon/avalon-pci.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+
+#include "avalon-core.h"
+
+#define DRIVER_NAME "avalon-dma"
+
+static unsigned int pci_bar = 0;
+module_param(pci_bar, uint, 0644);
+MODULE_PARM_DESC(pci_bar,
+		 "PCI BAR number the controller is mapped to (default: 0)");
+
+static unsigned int pci_msi_vector = 0;
+module_param(pci_msi_vector, uint, 0644);
+MODULE_PARM_DESC(pci_msi_vector,
+		 "MSI vector number used for the controller (default: 0)");
+
+static unsigned int pci_msi_count_order = 5;
+module_param(pci_msi_count_order, uint, 0644);
+MODULE_PARM_DESC(pci_msi_count_order,
+		 "Number of MSI vectors (order) device uses (default: 5)");
+
+static int init_interrupts(struct pci_dev *pci_dev)
+{
+	unsigned int nr_vecs = BIT(pci_msi_count_order);
+	int ret;
+
+	ret = pci_alloc_irq_vectors(pci_dev, nr_vecs, nr_vecs, PCI_IRQ_MSI);
+	if (ret < 0) {
+		return ret;
+
+	} else if (ret != nr_vecs) {
+		ret = -ENOSPC;
+		goto disable_msi;
+	}
+
+	ret = pci_irq_vector(pci_dev, pci_msi_vector);
+	if (ret < 0)
+		goto disable_msi;
+
+	return ret;
+
+disable_msi:
+	pci_disable_msi(pci_dev);
+
+	return ret;
+}
+
+static void term_interrupts(struct pci_dev *pci_dev)
+{
+	pci_disable_msi(pci_dev);
+}
+
+static int avalon_pci_probe(struct pci_dev *pci_dev,
+			    const struct pci_device_id *id)
+{
+	void *adma;
+	void __iomem *regs;
+	int ret;
+
+	ret = pci_enable_device(pci_dev);
+	if (ret)
+		return ret;
+
+	ret = pci_request_regions(pci_dev, DRIVER_NAME);
+	if (ret)
+		goto disable_device;
+
+	regs = pci_ioremap_bar(pci_dev, pci_bar);
+	if (!regs) {
+		ret = -ENOMEM;
+		goto release_regions;
+	}
+
+	ret = init_interrupts(pci_dev);
+	if (ret < 0)
+		goto unmap_bars;
+
+	adma = avalon_dma_register(&pci_dev->dev, regs, ret);
+	if (IS_ERR(adma)) {
+		ret = PTR_ERR(adma);
+		goto terminate_interrupts;
+	}
+
+	pci_set_master(pci_dev);
+	pci_set_drvdata(pci_dev, adma);
+
+	return 0;
+
+terminate_interrupts:
+	term_interrupts(pci_dev);
+
+unmap_bars:
+	pci_iounmap(pci_dev, regs);
+
+release_regions:
+	pci_release_regions(pci_dev);
+
+disable_device:
+	pci_disable_device(pci_dev);
+
+	return ret;
+}
+
+static void avalon_pci_remove(struct pci_dev *pci_dev)
+{
+	void *adma = pci_get_drvdata(pci_dev);
+	void __iomem *regs = avalon_dma_mmio(adma);
+
+	pci_set_drvdata(pci_dev, NULL);
+
+	avalon_dma_unregister(adma);
+	term_interrupts(pci_dev);
+
+	pci_iounmap(pci_dev, regs);
+	pci_release_regions(pci_dev);
+	pci_disable_device(pci_dev);
+}
+
+static struct pci_device_id avalon_pci_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_ALTERA, 0xe003) },
+	{ 0 }
+};
+
+static struct pci_driver avalon_pci_driver = {
+	.name		= DRIVER_NAME,
+	.id_table	= avalon_pci_ids,
+	.probe		= avalon_pci_probe,
+	.remove		= avalon_pci_remove,
+};
+
+module_pci_driver(avalon_pci_driver);
+
+MODULE_AUTHOR("Alexander Gordeev <a.gordeev.box@gmail.com>");
+MODULE_DESCRIPTION("Avalon-MM DMA Interface for PCIe");
+MODULE_LICENSE("GPL v2");
+MODULE_DEVICE_TABLE(pci, avalon_pci_ids);
-- 
2.24.0

Re: [PATCH v5 1/2] dmaengine: avalon-dma: Intel Avalon-MM DMA Interface for PCIe

[Vinod Koul]

On 06-11-19, 20:22, Alexander Gordeev wrote:

> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 7af874b69ffb..f6f43480a4a4 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -669,6 +669,8 @@ source "drivers/dma/sh/Kconfig"
>  
>  source "drivers/dma/ti/Kconfig"
>  
> +source "drivers/dma/avalon/Kconfig"

Sort this alphabetically please

> +
>  # clients
>  comment "DMA Clients"
>  	depends on DMA_ENGINE
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index f5ce8665e944..fd7e11417b73 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -75,6 +75,7 @@ obj-$(CONFIG_UNIPHIER_MDMAC) += uniphier-mdmac.o
>  obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
>  obj-$(CONFIG_ZX_DMA) += zx_dma.o
>  obj-$(CONFIG_ST_FDMA) += st_fdma.o
> +obj-$(CONFIG_AVALON_DMA) += avalon/

This one as well

> +config AVALON_DMA
> +	tristate "Intel Avalon-MM DMA Interface for PCIe"
> +	depends on PCI
> +	select DMA_ENGINE
> +	select DMA_VIRTUAL_CHANNELS
> +	help
> +	  This selects a driver for Avalon-MM DMA Interface for PCIe
> +	  hard IP block used in Intel Arria, Cyclone or Stratix FPGAs.

If it is just a single kconfig block, why not move it into dmaengine
Kconfig?

> +static unsigned int dma_mask_width = 64;
> +module_param(dma_mask_width, uint, 0644);
> +MODULE_PARM_DESC(dma_mask_width, "Avalon DMA bitmask width (default: 64)");
> +
> +unsigned long ctrl_base;
> +module_param(ctrl_base, ulong, 0644);
> +MODULE_PARM_DESC(ctrl_base, "Avalon DMA controller base (default: 0)");
> +
> +static unsigned int rd_ep_dst_lo = 0x80000000;
> +module_param(rd_ep_dst_lo, uint, 0644);
> +MODULE_PARM_DESC(rd_ep_dst_lo,
> +		 "Read status and desc table low (default: 0x80000000)");
> +
> +static unsigned int rd_ep_dst_hi = 0;
> +module_param(rd_ep_dst_hi, uint, 0644);
> +MODULE_PARM_DESC(rd_ep_dst_hi,
> +		 "Read status and desc table hi (default: 0)");
> +
> +static unsigned int wr_ep_dst_lo = 0x80002000;
> +module_param(wr_ep_dst_lo, uint, 0644);
> +MODULE_PARM_DESC(wr_ep_dst_lo,
> +		 "Write status and desc table low (default: 0x80002000)");
> +
> +static unsigned int wr_ep_dst_hi = 0;
> +module_param(wr_ep_dst_hi, uint, 0644);
> +MODULE_PARM_DESC(wr_ep_dst_hi,
> +		 "Write status and desc table hi (default: 0)");

these are resources, do you not have any other way, DT/ACPI/something
else to find these!

> +static void avalon_dma_term(struct avalon_dma *adma)
> +{
> +	struct avalon_dma_chan *chan = &adma->chan;
> +	struct avalon_dma_hw *hw = &chan->hw;
> +	struct device *dev = adma->dev;
> +
> +	free_irq(adma->irq, adma);

please also kill the vchan tasklet

> +static int avalon_dma_device_config(struct dma_chan *dma_chan,
> +				    struct dma_slave_config *config)
> +{
> +	struct avalon_dma_chan *chan = to_avalon_dma_chan(dma_chan);
> +
> +	if (!IS_ALIGNED(config->src_addr, sizeof(u32)) ||
> +	    !IS_ALIGNED(config->dst_addr, sizeof(u32)))
> +		return -EINVAL;
> +
> +	chan->src_addr = config->src_addr;
> +	chan->dst_addr = config->dst_addr;

hmmm you dont care about widths and burst sizes?

> +static struct dma_async_tx_descriptor *
> +avalon_dma_prep_slave_sg(struct dma_chan *dma_chan,
> +			 struct scatterlist *sg, unsigned int sg_len,
> +			 enum dma_transfer_direction direction,
> +			 unsigned long flags, void *context)
> +{
> +	struct avalon_dma_chan *chan = to_avalon_dma_chan(dma_chan);
> +	struct avalon_dma_desc *desc;
> +	dma_addr_t dev_addr;
> +	int i;
> +
> +	if (direction == DMA_MEM_TO_DEV)
> +		dev_addr = chan->dst_addr;
> +	else if (direction == DMA_DEV_TO_MEM)
> +		dev_addr = chan->src_addr;

the dst_addr/src_addr is initialized to -1 so dont you want to check you
have a valid address?

> +	else
> +		return NULL;
> +
> +	desc = kzalloc(struct_size(desc, seg, sg_len), GFP_NOWAIT);
> +	if (!desc)
> +		return NULL;
> +
> +	desc->direction = direction;
> +	desc->dev_addr	= dev_addr;
> +	desc->seg_curr	= 0;
> +	desc->seg_off	= 0;
> +	desc->nr_segs	= sg_len;
> +
> +	for (i = 0; i < sg_len; i++) {
> +		struct dma_segment *seg = &desc->seg[i];
> +		dma_addr_t dma_addr = sg_dma_address(sg);
> +		unsigned int dma_len = sg_dma_len(sg);
> +
> +		if (!IS_ALIGNED(dma_addr, sizeof(u32)) ||
> +		    !IS_ALIGNED(dma_len, sizeof(u32)))

you are leaking desc here

> +struct avalon_dma *avalon_dma_register(struct device *dev,
> +				       void __iomem *regs,
> +				       unsigned int irq)
> +{
> +	struct avalon_dma *adma;
> +	struct avalon_dma_chan *chan;
> +	struct dma_device *dma_dev;
> +	int ret;
> +
> +	adma = kzalloc(sizeof(*adma), GFP_KERNEL);
> +	if (!adma)
> +		return ERR_PTR(-ENOMEM);

any reason for not using device managed API for this?

> +static unsigned int pci_bar = 0;
> +module_param(pci_bar, uint, 0644);
> +MODULE_PARM_DESC(pci_bar,
> +		 "PCI BAR number the controller is mapped to (default: 0)");
> +
> +static unsigned int pci_msi_vector = 0;
> +module_param(pci_msi_vector, uint, 0644);
> +MODULE_PARM_DESC(pci_msi_vector,
> +		 "MSI vector number used for the controller (default: 0)");
> +
> +static unsigned int pci_msi_count_order = 5;
> +module_param(pci_msi_count_order, uint, 0644);
> +MODULE_PARM_DESC(pci_msi_count_order,
> +		 "Number of MSI vectors (order) device uses (default: 5)");

and still not convinced these should be module params
-- 
~Vinod

[PATCH RFC v5 2/2] dmaengine: avalon-test: Intel Avalon-MM DMA Interface for PCIe test

[Alexander Gordeev]

This is a sample implementation of a driver using "avalon-dma" to
perform data transfers between target device memory and system memory:

    +----------+    +----------+            +----------+
    |   RAM    |<-->|  Avalon  |<---PCIe--->|   Host   |
    +----------+    +----------+            +----------+

The target device is expected to use only Avalon-MM DMA Interface for
PCIe to initiate DMA transactions - without custom hardware specifics
to make such transfers possible.

Unlike "dmatest" driver, the contents of DMAed data is not manipulated by
"avalon-test" in any way. It is basically pass-through and the the data
are fully dependent on the target device implementation. Thus, it is up
to the users to analyze received or provide meaningful transmitted data.

CC: dmaengine@vger.kernel.org

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Alexander Gordeev <a.gordeev.box@gmail.com>
---
 drivers/dma/Kconfig                     |   1 +
 drivers/dma/Makefile                    |   1 +
 drivers/dma/avalon-test/Kconfig         |  12 +
 drivers/dma/avalon-test/Makefile        |  14 +
 drivers/dma/avalon-test/avalon-dev.c    | 108 +++++
 drivers/dma/avalon-test/avalon-dev.h    |  33 ++
 drivers/dma/avalon-test/avalon-ioctl.c  | 101 +++++
 drivers/dma/avalon-test/avalon-ioctl.h  |  13 +
 drivers/dma/avalon-test/avalon-mmap.c   |  74 +++
 drivers/dma/avalon-test/avalon-mmap.h   |  13 +
 drivers/dma/avalon-test/avalon-sg-buf.c | 132 ++++++
 drivers/dma/avalon-test/avalon-sg-buf.h |  27 ++
 drivers/dma/avalon-test/avalon-xfer.c   | 575 ++++++++++++++++++++++++
 drivers/dma/avalon-test/avalon-xfer.h   |  29 ++
 include/uapi/linux/avalon-ioctl.h       |  34 ++
 15 files changed, 1167 insertions(+)
 create mode 100644 drivers/dma/avalon-test/Kconfig
 create mode 100644 drivers/dma/avalon-test/Makefile
 create mode 100644 drivers/dma/avalon-test/avalon-dev.c
 create mode 100644 drivers/dma/avalon-test/avalon-dev.h
 create mode 100644 drivers/dma/avalon-test/avalon-ioctl.c
 create mode 100644 drivers/dma/avalon-test/avalon-ioctl.h
 create mode 100644 drivers/dma/avalon-test/avalon-mmap.c
 create mode 100644 drivers/dma/avalon-test/avalon-mmap.h
 create mode 100644 drivers/dma/avalon-test/avalon-sg-buf.c
 create mode 100644 drivers/dma/avalon-test/avalon-sg-buf.h
 create mode 100644 drivers/dma/avalon-test/avalon-xfer.c
 create mode 100644 drivers/dma/avalon-test/avalon-xfer.h
 create mode 100644 include/uapi/linux/avalon-ioctl.h

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index f6f43480a4a4..4b3c6a6baf4c 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -670,6 +670,7 @@ source "drivers/dma/sh/Kconfig"
 source "drivers/dma/ti/Kconfig"
 
 source "drivers/dma/avalon/Kconfig"
+source "drivers/dma/avalon-test/Kconfig"
 
 # clients
 comment "DMA Clients"
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index fd7e11417b73..eb3ee7f6cac6 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
 obj-$(CONFIG_ZX_DMA) += zx_dma.o
 obj-$(CONFIG_ST_FDMA) += st_fdma.o
 obj-$(CONFIG_AVALON_DMA) += avalon/
+obj-$(CONFIG_AVALON_TEST) += avalon-test/
 
 obj-y += mediatek/
 obj-y += qcom/
diff --git a/drivers/dma/avalon-test/Kconfig b/drivers/dma/avalon-test/Kconfig
new file mode 100644
index 000000000000..b4d22720ce23
--- /dev/null
+++ b/drivers/dma/avalon-test/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2019, The Linux Foundation. All rights reserved.
+# Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+#
+# Avalon DMA engine
+#
+config AVALON_TEST
+	select AVALON_DMA
+	tristate "Intel Avalon-MM DMA Interface for PCIe test driver"
+	help
+	  This selects a test driver for Avalon-MM DMA Interface for PCI
diff --git a/drivers/dma/avalon-test/Makefile b/drivers/dma/avalon-test/Makefile
new file mode 100644
index 000000000000..2387fc41c3ad
--- /dev/null
+++ b/drivers/dma/avalon-test/Makefile
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2019, The Linux Foundation. All rights reserved.
+# Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+#
+# Avalon DMA driver
+#
+obj-$(CONFIG_AVALON_TEST)	+= avalon-test.o
+
+avalon-test-objs :=	avalon-dev.o \
+			avalon-ioctl.o \
+			avalon-mmap.o \
+			avalon-sg-buf.o \
+			avalon-xfer.o
diff --git a/drivers/dma/avalon-test/avalon-dev.c b/drivers/dma/avalon-test/avalon-dev.c
new file mode 100644
index 000000000000..937ac3663efd
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-dev.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pci.h>
+
+#include "avalon-dev.h"
+#include "avalon-ioctl.h"
+#include "avalon-mmap.h"
+
+unsigned int mem_base = 0x70000000;
+module_param(mem_base, uint, 0644);
+MODULE_PARM_DESC(mem_base, "Device memory base (default: 0x70000000)");
+
+unsigned int mem_size = 0x10000000;
+module_param(mem_size, uint, 0644);
+MODULE_PARM_DESC(mem_size, "Device memory size (default: 0x10000000)");
+
+unsigned int dma_size = 0x200000;
+module_param(dma_size, uint, 0644);
+MODULE_PARM_DESC(dma_size, "DMA buffer transfer size (default: 0x200000)");
+
+unsigned int dma_size_sg = 0x10000000;
+module_param(dma_size_sg, uint, 0644);
+MODULE_PARM_DESC(dma_size_sg,
+		 "DMA scatter list transfer size (default: 0x10000000)");
+
+unsigned int nr_dma_reps = 4;
+module_param(nr_dma_reps, uint, 0644);
+MODULE_PARM_DESC(nr_dma_reps, "Device memory size (default: 4)");
+
+unsigned int dmas_per_cpu = 8;
+module_param(dmas_per_cpu, uint, 0644);
+MODULE_PARM_DESC(dmas_per_cpu, "Device memory size (default: 8)");
+
+static const struct file_operations avalon_dev_fops = {
+	.llseek		= generic_file_llseek,
+	.unlocked_ioctl	= avalon_dev_ioctl,
+	.mmap		= avalon_dev_mmap,
+};
+
+static struct avalon_dev avalon_dev;
+
+static bool filter(struct dma_chan *chan, void *filter_param)
+{
+	return !strcmp(chan->device->dev->driver->name, "avalon-dma");
+}
+
+static int __init avalon_drv_init(void)
+{
+	struct avalon_dev *adev = &avalon_dev;
+	struct dma_chan *chan;
+	dma_cap_mask_t mask;
+	int ret;
+
+	if (!IS_ALIGNED(mem_base, PAGE_SIZE) ||
+	    !IS_ALIGNED(mem_size, PAGE_SIZE) ||
+	    !IS_ALIGNED(dma_size, sizeof(u32)) ||
+	    !IS_ALIGNED(dma_size_sg, sizeof(u32)))
+		return -EINVAL;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	chan = dma_request_channel(mask, filter, NULL);
+	if (!chan)
+		return -ENODEV;
+
+	adev->dma_chan		= chan;
+
+	adev->misc_dev.minor	= MISC_DYNAMIC_MINOR;
+	adev->misc_dev.name	= DEVICE_NAME;
+	adev->misc_dev.nodename	= DEVICE_NAME;
+	adev->misc_dev.fops	= &avalon_dev_fops;
+	adev->misc_dev.mode	= 0644;
+
+	ret = misc_register(&adev->misc_dev);
+	if (ret) {
+		dma_release_channel(chan);
+		return ret;
+	}
+
+	dma_size = min(dma_size_sg, mem_size);
+	dma_size_sg = min(dma_size_sg, mem_size);
+
+	return 0;
+}
+
+static void __exit avalon_drv_exit(void)
+{
+	struct avalon_dev *adev = &avalon_dev;
+
+	misc_deregister(&adev->misc_dev);
+	dma_release_channel(adev->dma_chan);
+}
+
+module_init(avalon_drv_init);
+module_exit(avalon_drv_exit);
+
+MODULE_AUTHOR("Alexander Gordeev <a.gordeev.box@gmail.com>");
+MODULE_DESCRIPTION("Avalon DMA control driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/dma/avalon-test/avalon-dev.h b/drivers/dma/avalon-test/avalon-dev.h
new file mode 100644
index 000000000000..ad8f2f5717fa
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-dev.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#ifndef __AVALON_DEV_H__
+#define __AVALON_DEV_H__
+
+#include <linux/dmaengine.h>
+#include <linux/miscdevice.h>
+
+#define DEVICE_NAME		"avalon-dev"
+
+extern unsigned int mem_base;
+extern unsigned int mem_size;
+extern unsigned int dma_size;
+extern unsigned int dma_size_sg;
+extern unsigned int nr_dma_reps;
+extern unsigned int dmas_per_cpu;
+
+struct avalon_dev {
+	struct dma_chan *dma_chan;
+	struct miscdevice misc_dev;
+};
+
+static inline struct device *chan_to_dev(struct dma_chan *chan)
+{
+	return chan->device->dev;
+}
+
+#endif
diff --git a/drivers/dma/avalon-test/avalon-ioctl.c b/drivers/dma/avalon-test/avalon-ioctl.c
new file mode 100644
index 000000000000..39a6a7050ee5
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-ioctl.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/uio.h>
+
+#include <uapi/linux/avalon-ioctl.h>
+
+#include "avalon-ioctl.h"
+#include "avalon-xfer.h"
+
+long avalon_dev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct avalon_dev *adev = container_of(file->private_data,
+		struct avalon_dev, misc_dev);
+	struct dma_chan *chan = adev->dma_chan;
+	struct iovec iovec[2];
+	void __user *buf = NULL, *buf_rd = NULL, *buf_wr = NULL;
+	size_t len = 0, len_rd = 0, len_wr = 0;
+	int ret = -EINVAL;
+
+	switch (cmd) {
+	case IOCTL_AVALON_DMA_GET_INFO: {
+		struct avalon_dma_info info = {
+			.mem_addr	= mem_base,
+			.mem_size	= mem_size,
+			.dma_size	= dma_size,
+			.dma_size_sg	= dma_size_sg,
+		};
+
+		if (copy_to_user((void __user *)arg, &info, sizeof(info)))
+			return -EFAULT;
+
+		return 0;
+	}
+	case IOCTL_AVALON_DMA_SET_INFO:
+		return -EINVAL;
+	case IOCTL_AVALON_DMA_READ:
+	case IOCTL_AVALON_DMA_WRITE:
+	case IOCTL_AVALON_DMA_READ_SG:
+	case IOCTL_AVALON_DMA_WRITE_SG:
+	case IOCTL_AVALON_DMA_READ_SG_SMP:
+	case IOCTL_AVALON_DMA_WRITE_SG_SMP:
+		if (copy_from_user(iovec, (void __user *)arg, sizeof(iovec[0])))
+			return -EFAULT;
+
+		buf = iovec[0].iov_base;
+		len = iovec[0].iov_len;
+
+		break;
+	case IOCTL_AVALON_DMA_RDWR:
+	case IOCTL_AVALON_DMA_RDWR_SG:
+		if (copy_from_user(iovec, (void __user *)arg, sizeof(iovec)))
+			return -EFAULT;
+
+		buf_rd = iovec[0].iov_base;
+		len_rd = iovec[0].iov_len;
+
+		buf_wr = iovec[1].iov_base;
+		len_wr = iovec[1].iov_len;
+
+		break;
+	default:
+		return -EINVAL;
+	};
+
+	switch (cmd) {
+	case IOCTL_AVALON_DMA_READ:
+		ret = xfer_single(chan, DMA_DEV_TO_MEM, buf, len);
+		break;
+	case IOCTL_AVALON_DMA_WRITE:
+		ret = xfer_single(chan, DMA_MEM_TO_DEV, buf, len);
+		break;
+	case IOCTL_AVALON_DMA_RDWR:
+		ret = xfer_rw_single(chan, buf_rd, len_rd, buf_wr, len_wr);
+		break;
+	case IOCTL_AVALON_DMA_READ_SG:
+		ret = xfer_sg(chan, DMA_DEV_TO_MEM, buf, len, false);
+		break;
+	case IOCTL_AVALON_DMA_WRITE_SG:
+		ret = xfer_sg(chan, DMA_MEM_TO_DEV, buf, len, false);
+		break;
+	case IOCTL_AVALON_DMA_READ_SG_SMP:
+		ret = xfer_sg(chan, DMA_DEV_TO_MEM, buf, len, true);
+		break;
+	case IOCTL_AVALON_DMA_WRITE_SG_SMP:
+		ret = xfer_sg(chan, DMA_MEM_TO_DEV, buf, len, true);
+		break;
+	case IOCTL_AVALON_DMA_RDWR_SG:
+		ret = xfer_rw_sg(chan, buf_rd, len_rd, buf_wr, len_wr);
+		break;
+	};
+
+	return ret;
+}
diff --git a/drivers/dma/avalon-test/avalon-ioctl.h b/drivers/dma/avalon-test/avalon-ioctl.h
new file mode 100644
index 000000000000..a10ab0b5d67c
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-ioctl.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#ifndef __AVALON_IOCTL_H__
+#define __AVALON_IOCTL_H__
+
+long avalon_dev_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
+
+#endif
diff --git a/drivers/dma/avalon-test/avalon-mmap.c b/drivers/dma/avalon-test/avalon-mmap.c
new file mode 100644
index 000000000000..434a8f8d4720
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-mmap.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/dma-direction.h>
+
+#include "avalon-dev.h"
+#include "avalon-mmap.h"
+#include "avalon-sg-buf.h"
+
+static void avalon_drv_vm_close(struct vm_area_struct *vma)
+{
+	struct dma_sg_buf *sg_buf = vma->vm_private_data;
+
+	dma_sg_buf_free(sg_buf);
+}
+
+static const struct vm_operations_struct avalon_drv_vm_ops = {
+	.close	= avalon_drv_vm_close,
+};
+
+int avalon_dev_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct avalon_dev *adev = container_of(file->private_data,
+		struct avalon_dev, misc_dev);
+	struct device *dev = chan_to_dev(adev->dma_chan);
+	unsigned long addr = vma->vm_start;
+	unsigned long size = vma->vm_end - vma->vm_start;
+	enum dma_data_direction dir;
+	struct dma_sg_buf *sg_buf;
+	int ret;
+	int i;
+
+	if (!IS_ALIGNED(addr, PAGE_SIZE) || !IS_ALIGNED(size, PAGE_SIZE))
+		return -EINVAL;
+	if ((vma->vm_pgoff * PAGE_SIZE + size) > mem_size)
+		return -EINVAL;
+	if (!(((vma->vm_flags & (VM_READ | VM_WRITE)) == VM_READ) ||
+	      ((vma->vm_flags & (VM_READ | VM_WRITE)) == VM_WRITE)))
+		return -EINVAL;
+	if (!(vma->vm_flags & VM_SHARED))
+		return -EINVAL;
+
+	vma->vm_ops = &avalon_drv_vm_ops;
+
+	if (vma->vm_flags & VM_WRITE)
+		dir = DMA_TO_DEVICE;
+	else
+		dir = DMA_FROM_DEVICE;
+
+	sg_buf = dma_sg_buf_alloc(dev, size, dir, GFP_KERNEL);
+	if (IS_ERR(sg_buf))
+		return PTR_ERR(sg_buf);
+
+	for (i = 0; size > 0; i++) {
+		ret = vm_insert_page(vma, addr, sg_buf->pages[i]);
+		if (ret) {
+			dma_sg_buf_free(sg_buf);
+			return ret;
+		}
+
+		addr += PAGE_SIZE;
+		size -= PAGE_SIZE;
+	};
+
+	vma->vm_private_data = sg_buf;
+
+	return 0;
+}
diff --git a/drivers/dma/avalon-test/avalon-mmap.h b/drivers/dma/avalon-test/avalon-mmap.h
new file mode 100644
index 000000000000..3d3878f236cf
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-mmap.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#ifndef __AVALON_MMAP_H__
+#define __AVALON_MMAP_H__
+
+int avalon_dev_mmap(struct file *file, struct vm_area_struct *vma);
+
+#endif
diff --git a/drivers/dma/avalon-test/avalon-sg-buf.c b/drivers/dma/avalon-test/avalon-sg-buf.c
new file mode 100644
index 000000000000..31a578e20cc1
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-sg-buf.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#include <linux/kernel.h>
+#include <linux/dma-mapping.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+
+#include "avalon-sg-buf.h"
+
+static int dma_sg_alloc_compacted(struct dma_sg_buf *buf, gfp_t gfp_flags)
+{
+	unsigned int last_page = 0;
+	int size = buf->size;
+
+	while (size > 0) {
+		struct page *pages;
+		int order;
+		int i;
+
+		order = get_order(size);
+		if ((PAGE_SIZE << order) > size)
+			order--;
+
+		pages = NULL;
+		while (!pages) {
+			pages = alloc_pages(gfp_flags | __GFP_NOWARN, order);
+			if (pages)
+				break;
+
+			if (order == 0) {
+				while (last_page--)
+					__free_page(buf->pages[last_page]);
+				return -ENOMEM;
+			}
+			order--;
+		}
+
+		split_page(pages, order);
+		for (i = 0; i < (1 << order); i++)
+			buf->pages[last_page++] = &pages[i];
+
+		size -= PAGE_SIZE << order;
+	}
+
+	return 0;
+}
+
+struct dma_sg_buf *dma_sg_buf_alloc(struct device *dev,
+				    unsigned long size,
+				    enum dma_data_direction dma_dir,
+				    gfp_t gfp_flags)
+{
+	struct dma_sg_buf *buf;
+	struct sg_table *sgt;
+	int ret;
+	int num_pages;
+
+	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	buf->dma_dir = dma_dir;
+	buf->size = size;
+	buf->num_pages = size >> PAGE_SHIFT;
+
+	buf->pages = kvcalloc(buf->num_pages, sizeof(struct page *), GFP_KERNEL);
+	if (!buf->pages)
+		goto free_buf;
+
+	ret = dma_sg_alloc_compacted(buf, gfp_flags);
+	if (ret)
+		goto free_arr;
+
+	ret = sg_alloc_table_from_pages(&buf->sgt, buf->pages,
+					buf->num_pages, 0, size,
+					GFP_KERNEL);
+	if (ret)
+		goto free_pages;
+
+	buf->dev = get_device(dev);
+
+	sgt = &buf->sgt;
+
+	sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
+				      buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+	if (!sgt->nents)
+		goto free_sgt;
+
+	buf->vaddr = vm_map_ram(buf->pages, buf->num_pages, -1, PAGE_KERNEL);
+	if (!buf->vaddr)
+		goto unmap_sg;
+
+	return buf;
+
+unmap_sg:
+	dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
+			   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+free_sgt:
+	put_device(buf->dev);
+	sg_free_table(&buf->sgt);
+free_pages:
+	num_pages = buf->num_pages;
+	while (num_pages--)
+		__free_page(buf->pages[num_pages]);
+free_arr:
+	kvfree(buf->pages);
+free_buf:
+	kfree(buf);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+void dma_sg_buf_free(struct dma_sg_buf *buf)
+{
+	struct sg_table *sgt = &buf->sgt;
+	int i = buf->num_pages;
+
+	dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
+			   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+	vm_unmap_ram(buf->vaddr, buf->num_pages);
+	sg_free_table(&buf->sgt);
+	while (--i >= 0)
+		__free_page(buf->pages[i]);
+	kvfree(buf->pages);
+	put_device(buf->dev);
+	kfree(buf);
+}
diff --git a/drivers/dma/avalon-test/avalon-sg-buf.h b/drivers/dma/avalon-test/avalon-sg-buf.h
new file mode 100644
index 000000000000..a5cce1c18714
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-sg-buf.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ *
+ * Avalon DMA driver
+ */
+#ifndef __AVALON_SG_BUF_H__
+#define __AVALON_SG_BUF_H__
+
+struct dma_sg_buf {
+	struct device			*dev;
+	void				*vaddr;
+	struct page			**pages;
+	enum dma_data_direction		dma_dir;
+	struct sg_table			sgt;
+	size_t				size;
+	unsigned int			num_pages;
+};
+
+struct dma_sg_buf *dma_sg_buf_alloc(struct device *dev,
+				    unsigned long size,
+				    enum dma_data_direction dma_dir,
+				    gfp_t gfp_flags);
+void dma_sg_buf_free(struct dma_sg_buf *buf);
+
+#endif
diff --git a/drivers/dma/avalon-test/avalon-xfer.c b/drivers/dma/avalon-test/avalon-xfer.c
new file mode 100644
index 000000000000..57f3543bc7c3
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-xfer.c
@@ -0,0 +1,575 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/dma-mapping.h>
+#include <linux/uaccess.h>
+#include <linux/kthread.h>
+#include <linux/sched/signal.h>
+#include <linux/dmaengine.h>
+
+#include "avalon-xfer.h"
+#include "avalon-sg-buf.h"
+
+struct callback_info {
+	struct completion completion;
+	atomic_t counter;
+};
+
+static void init_callback_info(struct callback_info *info, int value)
+{
+	init_completion(&info->completion);
+
+	/*
+	 * Pairs with smp_rmb() in xfer_callback()
+	 */
+	atomic_set(&info->counter, value);
+	smp_wmb();
+}
+
+static void xfer_callback(void *arg)
+{
+	struct callback_info *info = arg;
+
+	/*
+	 * Pairs with smp_wmb() in init_callback_info()
+	 */
+	smp_rmb();
+	if (atomic_dec_and_test(&info->counter))
+		complete(&info->completion);
+}
+
+static int config_chan(struct dma_chan *chan,
+		       enum dma_transfer_direction direction,
+		       dma_addr_t dev_addr)
+{
+	struct dma_slave_config config = {
+		.direction	= direction,
+		.src_addr	= dev_addr,
+		.dst_addr	= dev_addr,
+	};
+
+	return dmaengine_slave_config(chan, &config);
+}
+
+static int submit_tx(struct dma_chan *chan,
+		     struct dma_async_tx_descriptor *tx,
+		     dma_async_tx_callback callback, void *callback_param)
+{
+	dma_cookie_t cookie;
+
+	tx->callback = callback;
+	tx->callback_param = callback_param;
+
+	cookie = dmaengine_submit(tx);
+	if (cookie < 0) {
+		dmaengine_terminate_sync(chan);
+		return cookie;
+	}
+
+	return 0;
+}
+
+static
+int submit_xfer_single(struct dma_chan *chan,
+		       enum dma_transfer_direction direction,
+		       dma_addr_t dev_addr,
+		       dma_addr_t host_addr, unsigned int size,
+		       dma_async_tx_callback callback, void *callback_param)
+{
+	struct dma_async_tx_descriptor *tx;
+	int ret;
+
+	ret = config_chan(chan, direction, dev_addr);
+	if (ret)
+		return ret;
+
+	tx = dmaengine_prep_slave_single(chan,
+					 host_addr, size, direction, 0);
+	if (!tx)
+		return -ENOMEM;
+
+	ret = submit_tx(chan, tx, callback, callback_param);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static
+int submit_xfer_sg(struct dma_chan *chan,
+		   enum dma_transfer_direction direction,
+		   dma_addr_t dev_addr,
+		   struct scatterlist *sg, unsigned int sg_len,
+		   dma_async_tx_callback callback, void *callback_param)
+{
+	struct dma_async_tx_descriptor *tx;
+	int ret;
+
+	ret = config_chan(chan, direction, dev_addr);
+	if (ret)
+		return ret;
+
+	tx = dmaengine_prep_slave_sg(chan, sg, sg_len, direction, 0);
+	if (!tx)
+		return -ENOMEM;
+
+	ret = submit_tx(chan, tx, callback, callback_param);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+int xfer_single(struct dma_chan *chan,
+		enum dma_transfer_direction direction,
+		void __user *user_buf, size_t user_len)
+{
+	struct device *dev = chan_to_dev(chan);
+	dma_addr_t dma_addr;
+	enum dma_data_direction dma_dir;
+	void *buf;
+	struct callback_info info;
+	int ret;
+	int i;
+
+	if (user_len < dma_size)
+		return -EINVAL;
+	if (direction == DMA_MEM_TO_DEV)
+		dma_dir = DMA_TO_DEVICE;
+	else if (direction == DMA_DEV_TO_MEM)
+		dma_dir = DMA_FROM_DEVICE;
+	else
+		return -EINVAL;
+
+	user_len = min_t(size_t, user_len, dma_size);
+
+	buf = kzalloc(dma_size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (direction == DMA_MEM_TO_DEV) {
+		if (copy_from_user(buf, user_buf, user_len)) {
+			ret = -EFAULT;
+			goto free_buf;
+		}
+	}
+
+	dma_addr = dma_map_single(dev, buf, dma_size, dma_dir);
+	if (dma_mapping_error(dev, dma_addr)) {
+		ret = -ENOMEM;
+		goto free_buf;
+	}
+
+	init_callback_info(&info, nr_dma_reps);
+
+	for (i = 0; i < nr_dma_reps; i++) {
+		ret = submit_xfer_single(chan, direction,
+					 mem_base, dma_addr, dma_size,
+					 xfer_callback, &info);
+		if (ret)
+			goto unmap_buf;
+	}
+
+	dma_async_issue_pending(chan);
+
+	ret = wait_for_completion_interruptible(&info.completion);
+	if (ret)
+		goto unmap_buf;
+
+	if (direction == DMA_DEV_TO_MEM) {
+		if (copy_to_user(user_buf, buf, user_len))
+			ret = -EFAULT;
+	}
+
+unmap_buf:
+	dma_unmap_single(dev, dma_addr, dma_size, dma_dir);
+
+free_buf:
+	kfree(buf);
+
+	return ret;
+}
+
+int xfer_rw_single(struct dma_chan *chan,
+		   void __user *user_buf_rd, size_t user_len_rd,
+		   void __user *user_buf_wr, size_t user_len_wr)
+{
+	struct device *dev = chan_to_dev(chan);
+	dma_addr_t target_rd = mem_base;
+	dma_addr_t target_wr = target_rd + dma_size;
+	dma_addr_t dma_addr_rd, dma_addr_wr;
+	void *buf_rd, *buf_wr;
+	struct callback_info info;
+	int ret;
+	int i;
+
+	if ((user_len_rd < dma_size) || (user_len_wr < dma_size))
+		return -EINVAL;
+
+	user_len_rd = min_t(size_t, user_len_rd, dma_size);
+	user_len_wr = min_t(size_t, user_len_wr, dma_size);
+
+	buf_rd = kzalloc(dma_size, GFP_KERNEL);
+	if (!buf_rd) {
+		ret = -ENOMEM;
+		goto alloc_err;
+	}
+
+	buf_wr = kzalloc(dma_size, GFP_KERNEL);
+	if (!buf_wr) {
+		ret = -ENOMEM;
+		goto free_buf_rd;
+	}
+
+	if (copy_from_user(buf_wr, user_buf_wr, user_len_wr)) {
+		ret = -EFAULT;
+		goto free_buf_wr;
+	}
+
+	dma_addr_rd = dma_map_single(dev, buf_rd, dma_size, DMA_DEV_TO_MEM);
+	if (dma_mapping_error(dev, dma_addr_rd)) {
+		ret = -ENOMEM;
+		goto free_buf_wr;
+	}
+
+	dma_addr_wr = dma_map_single(dev, buf_wr, dma_size, DMA_MEM_TO_DEV);
+	if (dma_mapping_error(dev, dma_addr_rd)) {
+		ret = -ENOMEM;
+		goto unmap_buf_rd;
+	}
+
+	init_callback_info(&info, 2 * nr_dma_reps);
+
+	for (i = 0; i < nr_dma_reps; i++) {
+		ret = submit_xfer_single(chan, DMA_MEM_TO_DEV,
+					 target_wr, dma_addr_wr, dma_size,
+					 xfer_callback, &info);
+		if (ret)
+			goto unmap_buf_wr;
+
+		ret = submit_xfer_single(chan, DMA_DEV_TO_MEM,
+					 target_rd, dma_addr_rd, dma_size,
+					 xfer_callback, &info);
+		if (ret)
+			goto unmap_buf_wr;
+	}
+
+	dma_async_issue_pending(chan);
+
+	ret = wait_for_completion_interruptible(&info.completion);
+	if (ret)
+		goto unmap_buf_wr;
+
+	if (copy_to_user(user_buf_rd, buf_rd, user_len_rd))
+		ret = -EFAULT;
+
+unmap_buf_wr:
+	dma_unmap_single(dev, dma_addr_wr, dma_size, DMA_MEM_TO_DEV);
+
+unmap_buf_rd:
+	dma_unmap_single(dev, dma_addr_rd, dma_size, DMA_DEV_TO_MEM);
+
+free_buf_wr:
+	kfree(buf_wr);
+
+free_buf_rd:
+	kfree(buf_rd);
+
+alloc_err:
+	return ret;
+}
+
+static int kthread_xfer_rw_sg(struct dma_chan *chan,
+			      enum dma_transfer_direction direction,
+			      dma_addr_t dev_addr,
+			      struct scatterlist *sg, unsigned int sg_len,
+			      dma_async_tx_callback callback)
+{
+	struct callback_info info;
+	int ret;
+	int i;
+
+	while (!kthread_should_stop()) {
+		init_callback_info(&info, nr_dma_reps);
+
+		for (i = 0; i < nr_dma_reps; i++) {
+			ret = submit_xfer_sg(chan, direction,
+					     dev_addr, sg, sg_len,
+					     callback, &info);
+			if (ret)
+				return ret;
+		}
+
+		dma_async_issue_pending(chan);
+
+		ret = wait_for_completion_interruptible(&info.completion);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+struct kthread_xfer_rw_sg_data {
+	struct dma_chan *chan;
+	enum dma_transfer_direction direction;
+	dma_addr_t dev_addr;
+	struct scatterlist *sg;
+	unsigned int sg_len;
+	dma_async_tx_callback callback;
+};
+
+static int __kthread_xfer_rw_sg(void *__data)
+{
+	struct kthread_xfer_rw_sg_data *data = __data;
+
+	return kthread_xfer_rw_sg(data->chan, data->direction,
+				  data->dev_addr, data->sg, data->sg_len,
+				  data->callback);
+}
+
+static int __xfer_sg_smp(struct dma_chan *chan,
+			 enum dma_transfer_direction direction,
+			 dma_addr_t dev_addr,
+			 struct scatterlist *sg, unsigned int sg_len,
+			 dma_async_tx_callback callback)
+{
+	struct kthread_xfer_rw_sg_data data = {
+		chan, direction,
+		dev_addr, sg, sg_len,
+		callback
+	};
+	struct task_struct *task;
+	struct task_struct **tasks;
+	int nr_tasks = dmas_per_cpu * num_online_cpus();
+	int n, cpu;
+	int ret = 0;
+	int i = 0;
+
+	tasks = kmalloc_array(nr_tasks, sizeof(tasks[0]), GFP_KERNEL);
+	if (!tasks)
+		return -ENOMEM;
+
+	for (n = 0; n < dmas_per_cpu; n++) {
+		for_each_online_cpu(cpu) {
+			if (i >= nr_tasks) {
+				ret = -ENOMEM;
+				goto kthread_err;
+			}
+
+			task = kthread_create(__kthread_xfer_rw_sg,
+					      &data, "avalon-dma-%d-%d",
+					      cpu, n);
+			if (IS_ERR(task)) {
+				ret = PTR_ERR(task);
+				goto kthread_err;
+			}
+
+			kthread_bind(task, cpu);
+
+			tasks[i] = task;
+			i++;
+		}
+	}
+
+	for (n = 0; n < i; n++)
+		wake_up_process(tasks[n]);
+
+	/*
+	 * Run child kthreads until user sent a signal (i.e Ctrl+C)
+	 * and clear the signal to avid user program from being killed.
+	 */
+	schedule_timeout_interruptible(MAX_SCHEDULE_TIMEOUT);
+	flush_signals(current);
+
+kthread_err:
+	while (--i >= 0)
+		kthread_stop(tasks[i]);
+
+	kfree(tasks);
+
+	return ret;
+}
+
+static int __xfer_sg(struct dma_chan *chan,
+		     enum dma_transfer_direction direction,
+		     dma_addr_t dev_addr,
+		     struct scatterlist *sg, unsigned int sg_len,
+		     dma_async_tx_callback callback)
+{
+	struct callback_info info;
+	int ret;
+	int i;
+
+	init_callback_info(&info, nr_dma_reps);
+
+	for (i = 0; i < nr_dma_reps; i++) {
+		ret = submit_xfer_sg(chan, direction, dev_addr, sg, sg_len,
+				     callback, &info);
+		if (ret)
+			return ret;
+	}
+
+	dma_async_issue_pending(chan);
+
+	ret = wait_for_completion_interruptible(&info.completion);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static struct vm_area_struct *get_vma(unsigned long addr,
+				      unsigned long size)
+{
+	struct vm_area_struct *vma;
+	unsigned long vm_size;
+
+	vma = find_vma(current->mm, addr);
+	if (!vma || (vma->vm_start != addr))
+		return ERR_PTR(-ENXIO);
+
+	vm_size = vma->vm_end - vma->vm_start;
+	if (size > vm_size)
+		return ERR_PTR(-EINVAL);
+
+	return vma;
+}
+
+int xfer_sg(struct dma_chan *chan,
+	    enum dma_transfer_direction direction,
+	    void __user *user_buf, size_t user_len,
+	    bool is_smp)
+{
+	struct device *dev = chan_to_dev(chan);
+	int (*xfer)(struct dma_chan *chan,
+		    enum dma_transfer_direction direction,
+		    dma_addr_t dev_addr,
+		    struct scatterlist *sg, unsigned int sg_len,
+		    dma_async_tx_callback callback);
+	struct vm_area_struct *vma;
+	struct dma_sg_buf *sg_buf;
+	dma_addr_t dma_addr;
+	int ret;
+
+	vma = get_vma((unsigned long)user_buf, user_len);
+	if (IS_ERR(vma))
+		return PTR_ERR(vma);
+
+	sg_buf = vma->vm_private_data;
+	switch (sg_buf->dma_dir) {
+	case DMA_TO_DEVICE:
+		if (direction != DMA_MEM_TO_DEV)
+			return -EINVAL;
+		break;
+	case DMA_FROM_DEVICE:
+		if (direction != DMA_DEV_TO_MEM)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (is_smp)
+		xfer = __xfer_sg_smp;
+	else
+		xfer = __xfer_sg;
+
+	dma_addr = mem_base + vma->vm_pgoff * PAGE_SIZE;
+
+	dma_sync_sg_for_device(dev,
+			       sg_buf->sgt.sgl, sg_buf->sgt.nents,
+			       sg_buf->dma_dir);
+
+	ret = xfer(chan, direction,
+		   dma_addr, sg_buf->sgt.sgl, sg_buf->sgt.nents,
+		   xfer_callback);
+
+	dma_sync_sg_for_cpu(dev,
+			    sg_buf->sgt.sgl, sg_buf->sgt.nents,
+			    sg_buf->dma_dir);
+
+	return ret;
+}
+
+int xfer_rw_sg(struct dma_chan *chan,
+	       void __user *user_buf_rd, size_t user_len_rd,
+	       void __user *user_buf_wr, size_t user_len_wr)
+{
+	struct device *dev = chan_to_dev(chan);
+	dma_addr_t dma_addr_rd, dma_addr_wr;
+	struct callback_info info;
+	struct vm_area_struct *vma_rd, *vma_wr;
+	struct dma_sg_buf *sg_buf_rd, *sg_buf_wr;
+	int ret;
+	int i;
+
+	vma_rd = get_vma((unsigned long)user_buf_rd, user_len_rd);
+	if (IS_ERR(vma_rd))
+		return PTR_ERR(vma_rd);
+
+	vma_wr = get_vma((unsigned long)user_buf_wr, user_len_wr);
+	if (IS_ERR(vma_wr))
+		return PTR_ERR(vma_wr);
+
+	sg_buf_rd = vma_rd->vm_private_data;
+	sg_buf_wr = vma_wr->vm_private_data;
+
+	if ((sg_buf_rd->dma_dir != DMA_TO_DEVICE) ||
+	    (sg_buf_wr->dma_dir != DMA_FROM_DEVICE))
+		return -EINVAL;
+
+	dma_addr_rd = mem_base + vma_rd->vm_pgoff * PAGE_SIZE;
+	dma_addr_wr = mem_base + vma_wr->vm_pgoff * PAGE_SIZE;
+
+	init_callback_info(&info, 2 * nr_dma_reps);
+
+	dma_sync_sg_for_device(dev,
+			       sg_buf_rd->sgt.sgl,
+			       sg_buf_rd->sgt.nents,
+			       DMA_FROM_DEVICE);
+	dma_sync_sg_for_device(dev,
+			       sg_buf_wr->sgt.sgl,
+			       sg_buf_wr->sgt.nents,
+			       DMA_TO_DEVICE);
+
+	for (i = 0; i < nr_dma_reps; i++) {
+		ret = submit_xfer_sg(chan, DMA_MEM_TO_DEV,
+				     dma_addr_wr,
+				     sg_buf_wr->sgt.sgl,
+				     sg_buf_wr->sgt.nents,
+				     xfer_callback, &info);
+		if (ret)
+			goto submit_err;
+
+		ret = submit_xfer_sg(chan, DMA_DEV_TO_MEM,
+				     dma_addr_rd,
+				     sg_buf_rd->sgt.sgl,
+				     sg_buf_rd->sgt.nents,
+				     xfer_callback, &info);
+		if (ret)
+			goto submit_err;
+	}
+
+	dma_async_issue_pending(chan);
+
+	ret = wait_for_completion_interruptible(&info.completion);
+
+submit_err:
+	dma_sync_sg_for_cpu(dev,
+			    sg_buf_rd->sgt.sgl,
+			    sg_buf_rd->sgt.nents,
+			    DMA_DEV_TO_MEM);
+	dma_sync_sg_for_cpu(dev,
+			    sg_buf_wr->sgt.sgl,
+			    sg_buf_wr->sgt.nents,
+			    DMA_MEM_TO_DEV);
+
+	return ret;
+}
diff --git a/drivers/dma/avalon-test/avalon-xfer.h b/drivers/dma/avalon-test/avalon-xfer.h
new file mode 100644
index 000000000000..32bc6c0e7fc9
--- /dev/null
+++ b/drivers/dma/avalon-test/avalon-xfer.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ *
+ * Avalon DMA driver
+ */
+#ifndef __AVALON_XFER_H__
+#define __AVALON_XFER_H__
+
+#include <linux/dmaengine.h>
+
+#include "avalon-dev.h"
+
+int xfer_single(struct dma_chan *chan,
+		enum dma_transfer_direction direction,
+		void __user *user_buf, size_t user_len);
+int xfer_rw_single(struct dma_chan *chan,
+		   void __user *user_buf_rd, size_t user_len_rd,
+		   void __user *user_buf_wr, size_t user_len_wr);
+int xfer_sg(struct dma_chan *chan,
+	    enum dma_transfer_direction direction,
+	    void __user *user_buf, size_t user_len,
+	    bool is_smp);
+int xfer_rw_sg(struct dma_chan *chan,
+	       void __user *user_buf_rd, size_t user_len_rd,
+	       void __user *user_buf_wr, size_t user_len_wr);
+
+#endif
diff --git a/include/uapi/linux/avalon-ioctl.h b/include/uapi/linux/avalon-ioctl.h
new file mode 100644
index 000000000000..a42d7b4bc0a2
--- /dev/null
+++ b/include/uapi/linux/avalon-ioctl.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Avalon DMA driver
+ *
+ * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
+ */
+#ifndef _UAPI_LINUX_AVALON_IOCTL_H__
+#define _UAPI_LINUX_AVALON_IOCTL_H__
+
+#include <linux/types.h>
+
+#define AVALON_DEVICE_NAME		"avalon-dev"
+
+struct avalon_dma_info {
+	size_t mem_addr;
+	size_t mem_size;
+	size_t dma_size;
+	size_t dma_size_sg;
+} __attribute((packed));
+
+#define AVALON_SIG 'V'
+
+#define IOCTL_AVALON_DMA_GET_INFO	_IOR(AVALON_SIG, 0, struct avalon_dma_info)
+#define IOCTL_AVALON_DMA_SET_INFO	_IOW(AVALON_SIG, 1, struct avalon_dma_info)
+#define IOCTL_AVALON_DMA_READ		_IOR(AVALON_SIG, 2, struct iovec)
+#define IOCTL_AVALON_DMA_WRITE		_IOW(AVALON_SIG, 3, struct iovec)
+#define IOCTL_AVALON_DMA_RDWR		_IOWR(AVALON_SIG, 4, struct iovec[2])
+#define IOCTL_AVALON_DMA_READ_SG	_IOR(AVALON_SIG, 5, struct iovec)
+#define IOCTL_AVALON_DMA_WRITE_SG	_IOW(AVALON_SIG, 6, struct iovec)
+#define IOCTL_AVALON_DMA_RDWR_SG	_IOWR(AVALON_SIG, 7, struct iovec[2])
+#define IOCTL_AVALON_DMA_READ_SG_SMP	_IOR(AVALON_SIG, 8, struct iovec)
+#define IOCTL_AVALON_DMA_WRITE_SG_SMP	_IOW(AVALON_SIG, 9, struct iovec)
+
+#endif
-- 
2.24.0

Re: [PATCH RFC v5 2/2] dmaengine: avalon-test: Intel Avalon-MM DMA Interface for PCIe test

[Vinod Koul]

On 06-11-19, 20:22, Alexander Gordeev wrote:
> This is a sample implementation of a driver using "avalon-dma" to
> perform data transfers between target device memory and system memory:
> 
>     +----------+    +----------+            +----------+
>     |   RAM    |<-->|  Avalon  |<---PCIe--->|   Host   |
>     +----------+    +----------+            +----------+
> 
> The target device is expected to use only Avalon-MM DMA Interface for
> PCIe to initiate DMA transactions - without custom hardware specifics
> to make such transfers possible.
> 
> Unlike "dmatest" driver, the contents of DMAed data is not manipulated by
> "avalon-test" in any way. It is basically pass-through and the the data
> are fully dependent on the target device implementation. Thus, it is up
> to the users to analyze received or provide meaningful transmitted data.

Is this the only reason why you have not used dmatest. If so, why not
add the feature to dmatest to optionally not check the DMAed data
contents?

> 
> CC: dmaengine@vger.kernel.org
> 
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Alexander Gordeev <a.gordeev.box@gmail.com>
> ---
>  drivers/dma/Kconfig                     |   1 +
>  drivers/dma/Makefile                    |   1 +
>  drivers/dma/avalon-test/Kconfig         |  12 +
>  drivers/dma/avalon-test/Makefile        |  14 +
>  drivers/dma/avalon-test/avalon-dev.c    | 108 +++++
>  drivers/dma/avalon-test/avalon-dev.h    |  33 ++
>  drivers/dma/avalon-test/avalon-ioctl.c  | 101 +++++
>  drivers/dma/avalon-test/avalon-ioctl.h  |  13 +
>  drivers/dma/avalon-test/avalon-mmap.c   |  74 +++
>  drivers/dma/avalon-test/avalon-mmap.h   |  13 +
>  drivers/dma/avalon-test/avalon-sg-buf.c | 132 ++++++
>  drivers/dma/avalon-test/avalon-sg-buf.h |  27 ++
>  drivers/dma/avalon-test/avalon-xfer.c   | 575 ++++++++++++++++++++++++
>  drivers/dma/avalon-test/avalon-xfer.h   |  29 ++
>  include/uapi/linux/avalon-ioctl.h       |  34 ++
>  15 files changed, 1167 insertions(+)
>  create mode 100644 drivers/dma/avalon-test/Kconfig
>  create mode 100644 drivers/dma/avalon-test/Makefile
>  create mode 100644 drivers/dma/avalon-test/avalon-dev.c
>  create mode 100644 drivers/dma/avalon-test/avalon-dev.h
>  create mode 100644 drivers/dma/avalon-test/avalon-ioctl.c
>  create mode 100644 drivers/dma/avalon-test/avalon-ioctl.h
>  create mode 100644 drivers/dma/avalon-test/avalon-mmap.c
>  create mode 100644 drivers/dma/avalon-test/avalon-mmap.h
>  create mode 100644 drivers/dma/avalon-test/avalon-sg-buf.c
>  create mode 100644 drivers/dma/avalon-test/avalon-sg-buf.h
>  create mode 100644 drivers/dma/avalon-test/avalon-xfer.c
>  create mode 100644 drivers/dma/avalon-test/avalon-xfer.h
>  create mode 100644 include/uapi/linux/avalon-ioctl.h
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index f6f43480a4a4..4b3c6a6baf4c 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -670,6 +670,7 @@ source "drivers/dma/sh/Kconfig"
>  source "drivers/dma/ti/Kconfig"
>  
>  source "drivers/dma/avalon/Kconfig"
> +source "drivers/dma/avalon-test/Kconfig"
>  
>  # clients
>  comment "DMA Clients"
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index fd7e11417b73..eb3ee7f6cac6 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
>  obj-$(CONFIG_ZX_DMA) += zx_dma.o
>  obj-$(CONFIG_ST_FDMA) += st_fdma.o
>  obj-$(CONFIG_AVALON_DMA) += avalon/
> +obj-$(CONFIG_AVALON_TEST) += avalon-test/
>  
>  obj-y += mediatek/
>  obj-y += qcom/
> diff --git a/drivers/dma/avalon-test/Kconfig b/drivers/dma/avalon-test/Kconfig
> new file mode 100644
> index 000000000000..b4d22720ce23
> --- /dev/null
> +++ b/drivers/dma/avalon-test/Kconfig
> @@ -0,0 +1,12 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Copyright (c) 2019, The Linux Foundation. All rights reserved.
> +# Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> +#
> +# Avalon DMA engine
> +#
> +config AVALON_TEST
> +	select AVALON_DMA
> +	tristate "Intel Avalon-MM DMA Interface for PCIe test driver"
> +	help
> +	  This selects a test driver for Avalon-MM DMA Interface for PCI
> diff --git a/drivers/dma/avalon-test/Makefile b/drivers/dma/avalon-test/Makefile
> new file mode 100644
> index 000000000000..2387fc41c3ad
> --- /dev/null
> +++ b/drivers/dma/avalon-test/Makefile
> @@ -0,0 +1,14 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Copyright (c) 2019, The Linux Foundation. All rights reserved.
> +# Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> +#
> +# Avalon DMA driver
> +#
> +obj-$(CONFIG_AVALON_TEST)	+= avalon-test.o
> +
> +avalon-test-objs :=	avalon-dev.o \
> +			avalon-ioctl.o \
> +			avalon-mmap.o \
> +			avalon-sg-buf.o \
> +			avalon-xfer.o
> diff --git a/drivers/dma/avalon-test/avalon-dev.c b/drivers/dma/avalon-test/avalon-dev.c
> new file mode 100644
> index 000000000000..937ac3663efd
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-dev.c
> @@ -0,0 +1,108 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/fs.h>
> +#include <linux/pci.h>
> +
> +#include "avalon-dev.h"
> +#include "avalon-ioctl.h"
> +#include "avalon-mmap.h"
> +
> +unsigned int mem_base = 0x70000000;
> +module_param(mem_base, uint, 0644);
> +MODULE_PARM_DESC(mem_base, "Device memory base (default: 0x70000000)");
> +
> +unsigned int mem_size = 0x10000000;
> +module_param(mem_size, uint, 0644);
> +MODULE_PARM_DESC(mem_size, "Device memory size (default: 0x10000000)");
> +
> +unsigned int dma_size = 0x200000;
> +module_param(dma_size, uint, 0644);
> +MODULE_PARM_DESC(dma_size, "DMA buffer transfer size (default: 0x200000)");
> +
> +unsigned int dma_size_sg = 0x10000000;
> +module_param(dma_size_sg, uint, 0644);
> +MODULE_PARM_DESC(dma_size_sg,
> +		 "DMA scatter list transfer size (default: 0x10000000)");
> +
> +unsigned int nr_dma_reps = 4;
> +module_param(nr_dma_reps, uint, 0644);
> +MODULE_PARM_DESC(nr_dma_reps, "Device memory size (default: 4)");
> +
> +unsigned int dmas_per_cpu = 8;
> +module_param(dmas_per_cpu, uint, 0644);
> +MODULE_PARM_DESC(dmas_per_cpu, "Device memory size (default: 8)");
> +
> +static const struct file_operations avalon_dev_fops = {
> +	.llseek		= generic_file_llseek,
> +	.unlocked_ioctl	= avalon_dev_ioctl,
> +	.mmap		= avalon_dev_mmap,
> +};
> +
> +static struct avalon_dev avalon_dev;
> +
> +static bool filter(struct dma_chan *chan, void *filter_param)
> +{
> +	return !strcmp(chan->device->dev->driver->name, "avalon-dma");
> +}
> +
> +static int __init avalon_drv_init(void)
> +{
> +	struct avalon_dev *adev = &avalon_dev;
> +	struct dma_chan *chan;
> +	dma_cap_mask_t mask;
> +	int ret;
> +
> +	if (!IS_ALIGNED(mem_base, PAGE_SIZE) ||
> +	    !IS_ALIGNED(mem_size, PAGE_SIZE) ||
> +	    !IS_ALIGNED(dma_size, sizeof(u32)) ||
> +	    !IS_ALIGNED(dma_size_sg, sizeof(u32)))
> +		return -EINVAL;
> +
> +	dma_cap_zero(mask);
> +	dma_cap_set(DMA_SLAVE, mask);
> +
> +	chan = dma_request_channel(mask, filter, NULL);
> +	if (!chan)
> +		return -ENODEV;
> +
> +	adev->dma_chan		= chan;
> +
> +	adev->misc_dev.minor	= MISC_DYNAMIC_MINOR;
> +	adev->misc_dev.name	= DEVICE_NAME;
> +	adev->misc_dev.nodename	= DEVICE_NAME;
> +	adev->misc_dev.fops	= &avalon_dev_fops;
> +	adev->misc_dev.mode	= 0644;
> +
> +	ret = misc_register(&adev->misc_dev);
> +	if (ret) {
> +		dma_release_channel(chan);
> +		return ret;
> +	}
> +
> +	dma_size = min(dma_size_sg, mem_size);
> +	dma_size_sg = min(dma_size_sg, mem_size);
> +
> +	return 0;
> +}
> +
> +static void __exit avalon_drv_exit(void)
> +{
> +	struct avalon_dev *adev = &avalon_dev;
> +
> +	misc_deregister(&adev->misc_dev);
> +	dma_release_channel(adev->dma_chan);
> +}
> +
> +module_init(avalon_drv_init);
> +module_exit(avalon_drv_exit);
> +
> +MODULE_AUTHOR("Alexander Gordeev <a.gordeev.box@gmail.com>");
> +MODULE_DESCRIPTION("Avalon DMA control driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/dma/avalon-test/avalon-dev.h b/drivers/dma/avalon-test/avalon-dev.h
> new file mode 100644
> index 000000000000..ad8f2f5717fa
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-dev.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#ifndef __AVALON_DEV_H__
> +#define __AVALON_DEV_H__
> +
> +#include <linux/dmaengine.h>
> +#include <linux/miscdevice.h>
> +
> +#define DEVICE_NAME		"avalon-dev"
> +
> +extern unsigned int mem_base;
> +extern unsigned int mem_size;
> +extern unsigned int dma_size;
> +extern unsigned int dma_size_sg;
> +extern unsigned int nr_dma_reps;
> +extern unsigned int dmas_per_cpu;
> +
> +struct avalon_dev {
> +	struct dma_chan *dma_chan;
> +	struct miscdevice misc_dev;
> +};
> +
> +static inline struct device *chan_to_dev(struct dma_chan *chan)
> +{
> +	return chan->device->dev;
> +}
> +
> +#endif
> diff --git a/drivers/dma/avalon-test/avalon-ioctl.c b/drivers/dma/avalon-test/avalon-ioctl.c
> new file mode 100644
> index 000000000000..39a6a7050ee5
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-ioctl.c
> @@ -0,0 +1,101 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/fs.h>
> +#include <linux/uio.h>
> +
> +#include <uapi/linux/avalon-ioctl.h>
> +
> +#include "avalon-ioctl.h"
> +#include "avalon-xfer.h"
> +
> +long avalon_dev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> +{
> +	struct avalon_dev *adev = container_of(file->private_data,
> +		struct avalon_dev, misc_dev);
> +	struct dma_chan *chan = adev->dma_chan;
> +	struct iovec iovec[2];
> +	void __user *buf = NULL, *buf_rd = NULL, *buf_wr = NULL;
> +	size_t len = 0, len_rd = 0, len_wr = 0;
> +	int ret = -EINVAL;
> +
> +	switch (cmd) {
> +	case IOCTL_AVALON_DMA_GET_INFO: {
> +		struct avalon_dma_info info = {
> +			.mem_addr	= mem_base,
> +			.mem_size	= mem_size,
> +			.dma_size	= dma_size,
> +			.dma_size_sg	= dma_size_sg,
> +		};
> +
> +		if (copy_to_user((void __user *)arg, &info, sizeof(info)))
> +			return -EFAULT;
> +
> +		return 0;
> +	}
> +	case IOCTL_AVALON_DMA_SET_INFO:
> +		return -EINVAL;
> +	case IOCTL_AVALON_DMA_READ:
> +	case IOCTL_AVALON_DMA_WRITE:
> +	case IOCTL_AVALON_DMA_READ_SG:
> +	case IOCTL_AVALON_DMA_WRITE_SG:
> +	case IOCTL_AVALON_DMA_READ_SG_SMP:
> +	case IOCTL_AVALON_DMA_WRITE_SG_SMP:
> +		if (copy_from_user(iovec, (void __user *)arg, sizeof(iovec[0])))
> +			return -EFAULT;
> +
> +		buf = iovec[0].iov_base;
> +		len = iovec[0].iov_len;
> +
> +		break;
> +	case IOCTL_AVALON_DMA_RDWR:
> +	case IOCTL_AVALON_DMA_RDWR_SG:
> +		if (copy_from_user(iovec, (void __user *)arg, sizeof(iovec)))
> +			return -EFAULT;
> +
> +		buf_rd = iovec[0].iov_base;
> +		len_rd = iovec[0].iov_len;
> +
> +		buf_wr = iovec[1].iov_base;
> +		len_wr = iovec[1].iov_len;
> +
> +		break;
> +	default:
> +		return -EINVAL;
> +	};
> +
> +	switch (cmd) {
> +	case IOCTL_AVALON_DMA_READ:
> +		ret = xfer_single(chan, DMA_DEV_TO_MEM, buf, len);
> +		break;
> +	case IOCTL_AVALON_DMA_WRITE:
> +		ret = xfer_single(chan, DMA_MEM_TO_DEV, buf, len);
> +		break;
> +	case IOCTL_AVALON_DMA_RDWR:
> +		ret = xfer_rw_single(chan, buf_rd, len_rd, buf_wr, len_wr);
> +		break;
> +	case IOCTL_AVALON_DMA_READ_SG:
> +		ret = xfer_sg(chan, DMA_DEV_TO_MEM, buf, len, false);
> +		break;
> +	case IOCTL_AVALON_DMA_WRITE_SG:
> +		ret = xfer_sg(chan, DMA_MEM_TO_DEV, buf, len, false);
> +		break;
> +	case IOCTL_AVALON_DMA_READ_SG_SMP:
> +		ret = xfer_sg(chan, DMA_DEV_TO_MEM, buf, len, true);
> +		break;
> +	case IOCTL_AVALON_DMA_WRITE_SG_SMP:
> +		ret = xfer_sg(chan, DMA_MEM_TO_DEV, buf, len, true);
> +		break;
> +	case IOCTL_AVALON_DMA_RDWR_SG:
> +		ret = xfer_rw_sg(chan, buf_rd, len_rd, buf_wr, len_wr);
> +		break;
> +	};
> +
> +	return ret;
> +}
> diff --git a/drivers/dma/avalon-test/avalon-ioctl.h b/drivers/dma/avalon-test/avalon-ioctl.h
> new file mode 100644
> index 000000000000..a10ab0b5d67c
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-ioctl.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#ifndef __AVALON_IOCTL_H__
> +#define __AVALON_IOCTL_H__
> +
> +long avalon_dev_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
> +
> +#endif
> diff --git a/drivers/dma/avalon-test/avalon-mmap.c b/drivers/dma/avalon-test/avalon-mmap.c
> new file mode 100644
> index 000000000000..434a8f8d4720
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-mmap.c
> @@ -0,0 +1,74 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#include <linux/kernel.h>
> +#include <linux/fs.h>
> +#include <linux/dma-direction.h>
> +
> +#include "avalon-dev.h"
> +#include "avalon-mmap.h"
> +#include "avalon-sg-buf.h"
> +
> +static void avalon_drv_vm_close(struct vm_area_struct *vma)
> +{
> +	struct dma_sg_buf *sg_buf = vma->vm_private_data;
> +
> +	dma_sg_buf_free(sg_buf);
> +}
> +
> +static const struct vm_operations_struct avalon_drv_vm_ops = {
> +	.close	= avalon_drv_vm_close,
> +};
> +
> +int avalon_dev_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> +	struct avalon_dev *adev = container_of(file->private_data,
> +		struct avalon_dev, misc_dev);
> +	struct device *dev = chan_to_dev(adev->dma_chan);
> +	unsigned long addr = vma->vm_start;
> +	unsigned long size = vma->vm_end - vma->vm_start;
> +	enum dma_data_direction dir;
> +	struct dma_sg_buf *sg_buf;
> +	int ret;
> +	int i;
> +
> +	if (!IS_ALIGNED(addr, PAGE_SIZE) || !IS_ALIGNED(size, PAGE_SIZE))
> +		return -EINVAL;
> +	if ((vma->vm_pgoff * PAGE_SIZE + size) > mem_size)
> +		return -EINVAL;
> +	if (!(((vma->vm_flags & (VM_READ | VM_WRITE)) == VM_READ) ||
> +	      ((vma->vm_flags & (VM_READ | VM_WRITE)) == VM_WRITE)))
> +		return -EINVAL;
> +	if (!(vma->vm_flags & VM_SHARED))
> +		return -EINVAL;
> +
> +	vma->vm_ops = &avalon_drv_vm_ops;
> +
> +	if (vma->vm_flags & VM_WRITE)
> +		dir = DMA_TO_DEVICE;
> +	else
> +		dir = DMA_FROM_DEVICE;
> +
> +	sg_buf = dma_sg_buf_alloc(dev, size, dir, GFP_KERNEL);
> +	if (IS_ERR(sg_buf))
> +		return PTR_ERR(sg_buf);
> +
> +	for (i = 0; size > 0; i++) {
> +		ret = vm_insert_page(vma, addr, sg_buf->pages[i]);
> +		if (ret) {
> +			dma_sg_buf_free(sg_buf);
> +			return ret;
> +		}
> +
> +		addr += PAGE_SIZE;
> +		size -= PAGE_SIZE;
> +	};
> +
> +	vma->vm_private_data = sg_buf;
> +
> +	return 0;
> +}
> diff --git a/drivers/dma/avalon-test/avalon-mmap.h b/drivers/dma/avalon-test/avalon-mmap.h
> new file mode 100644
> index 000000000000..3d3878f236cf
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-mmap.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#ifndef __AVALON_MMAP_H__
> +#define __AVALON_MMAP_H__
> +
> +int avalon_dev_mmap(struct file *file, struct vm_area_struct *vma);
> +
> +#endif
> diff --git a/drivers/dma/avalon-test/avalon-sg-buf.c b/drivers/dma/avalon-test/avalon-sg-buf.c
> new file mode 100644
> index 000000000000..31a578e20cc1
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-sg-buf.c
> @@ -0,0 +1,132 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#include <linux/kernel.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/vmalloc.h>
> +#include <linux/slab.h>
> +
> +#include "avalon-sg-buf.h"
> +
> +static int dma_sg_alloc_compacted(struct dma_sg_buf *buf, gfp_t gfp_flags)
> +{
> +	unsigned int last_page = 0;
> +	int size = buf->size;
> +
> +	while (size > 0) {
> +		struct page *pages;
> +		int order;
> +		int i;
> +
> +		order = get_order(size);
> +		if ((PAGE_SIZE << order) > size)
> +			order--;
> +
> +		pages = NULL;
> +		while (!pages) {
> +			pages = alloc_pages(gfp_flags | __GFP_NOWARN, order);
> +			if (pages)
> +				break;
> +
> +			if (order == 0) {
> +				while (last_page--)
> +					__free_page(buf->pages[last_page]);
> +				return -ENOMEM;
> +			}
> +			order--;
> +		}
> +
> +		split_page(pages, order);
> +		for (i = 0; i < (1 << order); i++)
> +			buf->pages[last_page++] = &pages[i];
> +
> +		size -= PAGE_SIZE << order;
> +	}
> +
> +	return 0;
> +}
> +
> +struct dma_sg_buf *dma_sg_buf_alloc(struct device *dev,
> +				    unsigned long size,
> +				    enum dma_data_direction dma_dir,
> +				    gfp_t gfp_flags)
> +{
> +	struct dma_sg_buf *buf;
> +	struct sg_table *sgt;
> +	int ret;
> +	int num_pages;
> +
> +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
> +	if (!buf)
> +		return ERR_PTR(-ENOMEM);
> +
> +	buf->dma_dir = dma_dir;
> +	buf->size = size;
> +	buf->num_pages = size >> PAGE_SHIFT;
> +
> +	buf->pages = kvcalloc(buf->num_pages, sizeof(struct page *), GFP_KERNEL);
> +	if (!buf->pages)
> +		goto free_buf;
> +
> +	ret = dma_sg_alloc_compacted(buf, gfp_flags);
> +	if (ret)
> +		goto free_arr;
> +
> +	ret = sg_alloc_table_from_pages(&buf->sgt, buf->pages,
> +					buf->num_pages, 0, size,
> +					GFP_KERNEL);
> +	if (ret)
> +		goto free_pages;
> +
> +	buf->dev = get_device(dev);
> +
> +	sgt = &buf->sgt;
> +
> +	sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> +				      buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
> +	if (!sgt->nents)
> +		goto free_sgt;
> +
> +	buf->vaddr = vm_map_ram(buf->pages, buf->num_pages, -1, PAGE_KERNEL);
> +	if (!buf->vaddr)
> +		goto unmap_sg;
> +
> +	return buf;
> +
> +unmap_sg:
> +	dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> +			   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
> +free_sgt:
> +	put_device(buf->dev);
> +	sg_free_table(&buf->sgt);
> +free_pages:
> +	num_pages = buf->num_pages;
> +	while (num_pages--)
> +		__free_page(buf->pages[num_pages]);
> +free_arr:
> +	kvfree(buf->pages);
> +free_buf:
> +	kfree(buf);
> +
> +	return ERR_PTR(-ENOMEM);
> +}
> +
> +void dma_sg_buf_free(struct dma_sg_buf *buf)
> +{
> +	struct sg_table *sgt = &buf->sgt;
> +	int i = buf->num_pages;
> +
> +	dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> +			   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
> +	vm_unmap_ram(buf->vaddr, buf->num_pages);
> +	sg_free_table(&buf->sgt);
> +	while (--i >= 0)
> +		__free_page(buf->pages[i]);
> +	kvfree(buf->pages);
> +	put_device(buf->dev);
> +	kfree(buf);
> +}
> diff --git a/drivers/dma/avalon-test/avalon-sg-buf.h b/drivers/dma/avalon-test/avalon-sg-buf.h
> new file mode 100644
> index 000000000000..a5cce1c18714
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-sg-buf.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + *
> + * Avalon DMA driver
> + */
> +#ifndef __AVALON_SG_BUF_H__
> +#define __AVALON_SG_BUF_H__
> +
> +struct dma_sg_buf {
> +	struct device			*dev;
> +	void				*vaddr;
> +	struct page			**pages;
> +	enum dma_data_direction		dma_dir;
> +	struct sg_table			sgt;
> +	size_t				size;
> +	unsigned int			num_pages;
> +};
> +
> +struct dma_sg_buf *dma_sg_buf_alloc(struct device *dev,
> +				    unsigned long size,
> +				    enum dma_data_direction dma_dir,
> +				    gfp_t gfp_flags);
> +void dma_sg_buf_free(struct dma_sg_buf *buf);
> +
> +#endif
> diff --git a/drivers/dma/avalon-test/avalon-xfer.c b/drivers/dma/avalon-test/avalon-xfer.c
> new file mode 100644
> index 000000000000..57f3543bc7c3
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-xfer.c
> @@ -0,0 +1,575 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/uaccess.h>
> +#include <linux/kthread.h>
> +#include <linux/sched/signal.h>
> +#include <linux/dmaengine.h>
> +
> +#include "avalon-xfer.h"
> +#include "avalon-sg-buf.h"
> +
> +struct callback_info {
> +	struct completion completion;
> +	atomic_t counter;
> +};
> +
> +static void init_callback_info(struct callback_info *info, int value)
> +{
> +	init_completion(&info->completion);
> +
> +	/*
> +	 * Pairs with smp_rmb() in xfer_callback()
> +	 */
> +	atomic_set(&info->counter, value);
> +	smp_wmb();
> +}
> +
> +static void xfer_callback(void *arg)
> +{
> +	struct callback_info *info = arg;
> +
> +	/*
> +	 * Pairs with smp_wmb() in init_callback_info()
> +	 */
> +	smp_rmb();
> +	if (atomic_dec_and_test(&info->counter))
> +		complete(&info->completion);
> +}
> +
> +static int config_chan(struct dma_chan *chan,
> +		       enum dma_transfer_direction direction,
> +		       dma_addr_t dev_addr)
> +{
> +	struct dma_slave_config config = {
> +		.direction	= direction,
> +		.src_addr	= dev_addr,
> +		.dst_addr	= dev_addr,
> +	};
> +
> +	return dmaengine_slave_config(chan, &config);
> +}
> +
> +static int submit_tx(struct dma_chan *chan,
> +		     struct dma_async_tx_descriptor *tx,
> +		     dma_async_tx_callback callback, void *callback_param)
> +{
> +	dma_cookie_t cookie;
> +
> +	tx->callback = callback;
> +	tx->callback_param = callback_param;
> +
> +	cookie = dmaengine_submit(tx);
> +	if (cookie < 0) {
> +		dmaengine_terminate_sync(chan);
> +		return cookie;
> +	}
> +
> +	return 0;
> +}
> +
> +static
> +int submit_xfer_single(struct dma_chan *chan,
> +		       enum dma_transfer_direction direction,
> +		       dma_addr_t dev_addr,
> +		       dma_addr_t host_addr, unsigned int size,
> +		       dma_async_tx_callback callback, void *callback_param)
> +{
> +	struct dma_async_tx_descriptor *tx;
> +	int ret;
> +
> +	ret = config_chan(chan, direction, dev_addr);
> +	if (ret)
> +		return ret;
> +
> +	tx = dmaengine_prep_slave_single(chan,
> +					 host_addr, size, direction, 0);
> +	if (!tx)
> +		return -ENOMEM;
> +
> +	ret = submit_tx(chan, tx, callback, callback_param);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static
> +int submit_xfer_sg(struct dma_chan *chan,
> +		   enum dma_transfer_direction direction,
> +		   dma_addr_t dev_addr,
> +		   struct scatterlist *sg, unsigned int sg_len,
> +		   dma_async_tx_callback callback, void *callback_param)
> +{
> +	struct dma_async_tx_descriptor *tx;
> +	int ret;
> +
> +	ret = config_chan(chan, direction, dev_addr);
> +	if (ret)
> +		return ret;
> +
> +	tx = dmaengine_prep_slave_sg(chan, sg, sg_len, direction, 0);
> +	if (!tx)
> +		return -ENOMEM;
> +
> +	ret = submit_tx(chan, tx, callback, callback_param);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +int xfer_single(struct dma_chan *chan,
> +		enum dma_transfer_direction direction,
> +		void __user *user_buf, size_t user_len)
> +{
> +	struct device *dev = chan_to_dev(chan);
> +	dma_addr_t dma_addr;
> +	enum dma_data_direction dma_dir;
> +	void *buf;
> +	struct callback_info info;
> +	int ret;
> +	int i;
> +
> +	if (user_len < dma_size)
> +		return -EINVAL;
> +	if (direction == DMA_MEM_TO_DEV)
> +		dma_dir = DMA_TO_DEVICE;
> +	else if (direction == DMA_DEV_TO_MEM)
> +		dma_dir = DMA_FROM_DEVICE;
> +	else
> +		return -EINVAL;
> +
> +	user_len = min_t(size_t, user_len, dma_size);
> +
> +	buf = kzalloc(dma_size, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	if (direction == DMA_MEM_TO_DEV) {
> +		if (copy_from_user(buf, user_buf, user_len)) {
> +			ret = -EFAULT;
> +			goto free_buf;
> +		}
> +	}
> +
> +	dma_addr = dma_map_single(dev, buf, dma_size, dma_dir);
> +	if (dma_mapping_error(dev, dma_addr)) {
> +		ret = -ENOMEM;
> +		goto free_buf;
> +	}
> +
> +	init_callback_info(&info, nr_dma_reps);
> +
> +	for (i = 0; i < nr_dma_reps; i++) {
> +		ret = submit_xfer_single(chan, direction,
> +					 mem_base, dma_addr, dma_size,
> +					 xfer_callback, &info);
> +		if (ret)
> +			goto unmap_buf;
> +	}
> +
> +	dma_async_issue_pending(chan);
> +
> +	ret = wait_for_completion_interruptible(&info.completion);
> +	if (ret)
> +		goto unmap_buf;
> +
> +	if (direction == DMA_DEV_TO_MEM) {
> +		if (copy_to_user(user_buf, buf, user_len))
> +			ret = -EFAULT;
> +	}
> +
> +unmap_buf:
> +	dma_unmap_single(dev, dma_addr, dma_size, dma_dir);
> +
> +free_buf:
> +	kfree(buf);
> +
> +	return ret;
> +}
> +
> +int xfer_rw_single(struct dma_chan *chan,
> +		   void __user *user_buf_rd, size_t user_len_rd,
> +		   void __user *user_buf_wr, size_t user_len_wr)
> +{
> +	struct device *dev = chan_to_dev(chan);
> +	dma_addr_t target_rd = mem_base;
> +	dma_addr_t target_wr = target_rd + dma_size;
> +	dma_addr_t dma_addr_rd, dma_addr_wr;
> +	void *buf_rd, *buf_wr;
> +	struct callback_info info;
> +	int ret;
> +	int i;
> +
> +	if ((user_len_rd < dma_size) || (user_len_wr < dma_size))
> +		return -EINVAL;
> +
> +	user_len_rd = min_t(size_t, user_len_rd, dma_size);
> +	user_len_wr = min_t(size_t, user_len_wr, dma_size);
> +
> +	buf_rd = kzalloc(dma_size, GFP_KERNEL);
> +	if (!buf_rd) {
> +		ret = -ENOMEM;
> +		goto alloc_err;
> +	}
> +
> +	buf_wr = kzalloc(dma_size, GFP_KERNEL);
> +	if (!buf_wr) {
> +		ret = -ENOMEM;
> +		goto free_buf_rd;
> +	}
> +
> +	if (copy_from_user(buf_wr, user_buf_wr, user_len_wr)) {
> +		ret = -EFAULT;
> +		goto free_buf_wr;
> +	}
> +
> +	dma_addr_rd = dma_map_single(dev, buf_rd, dma_size, DMA_DEV_TO_MEM);
> +	if (dma_mapping_error(dev, dma_addr_rd)) {
> +		ret = -ENOMEM;
> +		goto free_buf_wr;
> +	}
> +
> +	dma_addr_wr = dma_map_single(dev, buf_wr, dma_size, DMA_MEM_TO_DEV);
> +	if (dma_mapping_error(dev, dma_addr_rd)) {
> +		ret = -ENOMEM;
> +		goto unmap_buf_rd;
> +	}
> +
> +	init_callback_info(&info, 2 * nr_dma_reps);
> +
> +	for (i = 0; i < nr_dma_reps; i++) {
> +		ret = submit_xfer_single(chan, DMA_MEM_TO_DEV,
> +					 target_wr, dma_addr_wr, dma_size,
> +					 xfer_callback, &info);
> +		if (ret)
> +			goto unmap_buf_wr;
> +
> +		ret = submit_xfer_single(chan, DMA_DEV_TO_MEM,
> +					 target_rd, dma_addr_rd, dma_size,
> +					 xfer_callback, &info);
> +		if (ret)
> +			goto unmap_buf_wr;
> +	}
> +
> +	dma_async_issue_pending(chan);
> +
> +	ret = wait_for_completion_interruptible(&info.completion);
> +	if (ret)
> +		goto unmap_buf_wr;
> +
> +	if (copy_to_user(user_buf_rd, buf_rd, user_len_rd))
> +		ret = -EFAULT;
> +
> +unmap_buf_wr:
> +	dma_unmap_single(dev, dma_addr_wr, dma_size, DMA_MEM_TO_DEV);
> +
> +unmap_buf_rd:
> +	dma_unmap_single(dev, dma_addr_rd, dma_size, DMA_DEV_TO_MEM);
> +
> +free_buf_wr:
> +	kfree(buf_wr);
> +
> +free_buf_rd:
> +	kfree(buf_rd);
> +
> +alloc_err:
> +	return ret;
> +}
> +
> +static int kthread_xfer_rw_sg(struct dma_chan *chan,
> +			      enum dma_transfer_direction direction,
> +			      dma_addr_t dev_addr,
> +			      struct scatterlist *sg, unsigned int sg_len,
> +			      dma_async_tx_callback callback)
> +{
> +	struct callback_info info;
> +	int ret;
> +	int i;
> +
> +	while (!kthread_should_stop()) {
> +		init_callback_info(&info, nr_dma_reps);
> +
> +		for (i = 0; i < nr_dma_reps; i++) {
> +			ret = submit_xfer_sg(chan, direction,
> +					     dev_addr, sg, sg_len,
> +					     callback, &info);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		dma_async_issue_pending(chan);
> +
> +		ret = wait_for_completion_interruptible(&info.completion);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +struct kthread_xfer_rw_sg_data {
> +	struct dma_chan *chan;
> +	enum dma_transfer_direction direction;
> +	dma_addr_t dev_addr;
> +	struct scatterlist *sg;
> +	unsigned int sg_len;
> +	dma_async_tx_callback callback;
> +};
> +
> +static int __kthread_xfer_rw_sg(void *__data)
> +{
> +	struct kthread_xfer_rw_sg_data *data = __data;
> +
> +	return kthread_xfer_rw_sg(data->chan, data->direction,
> +				  data->dev_addr, data->sg, data->sg_len,
> +				  data->callback);
> +}
> +
> +static int __xfer_sg_smp(struct dma_chan *chan,
> +			 enum dma_transfer_direction direction,
> +			 dma_addr_t dev_addr,
> +			 struct scatterlist *sg, unsigned int sg_len,
> +			 dma_async_tx_callback callback)
> +{
> +	struct kthread_xfer_rw_sg_data data = {
> +		chan, direction,
> +		dev_addr, sg, sg_len,
> +		callback
> +	};
> +	struct task_struct *task;
> +	struct task_struct **tasks;
> +	int nr_tasks = dmas_per_cpu * num_online_cpus();
> +	int n, cpu;
> +	int ret = 0;
> +	int i = 0;
> +
> +	tasks = kmalloc_array(nr_tasks, sizeof(tasks[0]), GFP_KERNEL);
> +	if (!tasks)
> +		return -ENOMEM;
> +
> +	for (n = 0; n < dmas_per_cpu; n++) {
> +		for_each_online_cpu(cpu) {
> +			if (i >= nr_tasks) {
> +				ret = -ENOMEM;
> +				goto kthread_err;
> +			}
> +
> +			task = kthread_create(__kthread_xfer_rw_sg,
> +					      &data, "avalon-dma-%d-%d",
> +					      cpu, n);
> +			if (IS_ERR(task)) {
> +				ret = PTR_ERR(task);
> +				goto kthread_err;
> +			}
> +
> +			kthread_bind(task, cpu);
> +
> +			tasks[i] = task;
> +			i++;
> +		}
> +	}
> +
> +	for (n = 0; n < i; n++)
> +		wake_up_process(tasks[n]);
> +
> +	/*
> +	 * Run child kthreads until user sent a signal (i.e Ctrl+C)
> +	 * and clear the signal to avid user program from being killed.
> +	 */
> +	schedule_timeout_interruptible(MAX_SCHEDULE_TIMEOUT);
> +	flush_signals(current);
> +
> +kthread_err:
> +	while (--i >= 0)
> +		kthread_stop(tasks[i]);
> +
> +	kfree(tasks);
> +
> +	return ret;
> +}
> +
> +static int __xfer_sg(struct dma_chan *chan,
> +		     enum dma_transfer_direction direction,
> +		     dma_addr_t dev_addr,
> +		     struct scatterlist *sg, unsigned int sg_len,
> +		     dma_async_tx_callback callback)
> +{
> +	struct callback_info info;
> +	int ret;
> +	int i;
> +
> +	init_callback_info(&info, nr_dma_reps);
> +
> +	for (i = 0; i < nr_dma_reps; i++) {
> +		ret = submit_xfer_sg(chan, direction, dev_addr, sg, sg_len,
> +				     callback, &info);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	dma_async_issue_pending(chan);
> +
> +	ret = wait_for_completion_interruptible(&info.completion);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static struct vm_area_struct *get_vma(unsigned long addr,
> +				      unsigned long size)
> +{
> +	struct vm_area_struct *vma;
> +	unsigned long vm_size;
> +
> +	vma = find_vma(current->mm, addr);
> +	if (!vma || (vma->vm_start != addr))
> +		return ERR_PTR(-ENXIO);
> +
> +	vm_size = vma->vm_end - vma->vm_start;
> +	if (size > vm_size)
> +		return ERR_PTR(-EINVAL);
> +
> +	return vma;
> +}
> +
> +int xfer_sg(struct dma_chan *chan,
> +	    enum dma_transfer_direction direction,
> +	    void __user *user_buf, size_t user_len,
> +	    bool is_smp)
> +{
> +	struct device *dev = chan_to_dev(chan);
> +	int (*xfer)(struct dma_chan *chan,
> +		    enum dma_transfer_direction direction,
> +		    dma_addr_t dev_addr,
> +		    struct scatterlist *sg, unsigned int sg_len,
> +		    dma_async_tx_callback callback);
> +	struct vm_area_struct *vma;
> +	struct dma_sg_buf *sg_buf;
> +	dma_addr_t dma_addr;
> +	int ret;
> +
> +	vma = get_vma((unsigned long)user_buf, user_len);
> +	if (IS_ERR(vma))
> +		return PTR_ERR(vma);
> +
> +	sg_buf = vma->vm_private_data;
> +	switch (sg_buf->dma_dir) {
> +	case DMA_TO_DEVICE:
> +		if (direction != DMA_MEM_TO_DEV)
> +			return -EINVAL;
> +		break;
> +	case DMA_FROM_DEVICE:
> +		if (direction != DMA_DEV_TO_MEM)
> +			return -EINVAL;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (is_smp)
> +		xfer = __xfer_sg_smp;
> +	else
> +		xfer = __xfer_sg;
> +
> +	dma_addr = mem_base + vma->vm_pgoff * PAGE_SIZE;
> +
> +	dma_sync_sg_for_device(dev,
> +			       sg_buf->sgt.sgl, sg_buf->sgt.nents,
> +			       sg_buf->dma_dir);
> +
> +	ret = xfer(chan, direction,
> +		   dma_addr, sg_buf->sgt.sgl, sg_buf->sgt.nents,
> +		   xfer_callback);
> +
> +	dma_sync_sg_for_cpu(dev,
> +			    sg_buf->sgt.sgl, sg_buf->sgt.nents,
> +			    sg_buf->dma_dir);
> +
> +	return ret;
> +}
> +
> +int xfer_rw_sg(struct dma_chan *chan,
> +	       void __user *user_buf_rd, size_t user_len_rd,
> +	       void __user *user_buf_wr, size_t user_len_wr)
> +{
> +	struct device *dev = chan_to_dev(chan);
> +	dma_addr_t dma_addr_rd, dma_addr_wr;
> +	struct callback_info info;
> +	struct vm_area_struct *vma_rd, *vma_wr;
> +	struct dma_sg_buf *sg_buf_rd, *sg_buf_wr;
> +	int ret;
> +	int i;
> +
> +	vma_rd = get_vma((unsigned long)user_buf_rd, user_len_rd);
> +	if (IS_ERR(vma_rd))
> +		return PTR_ERR(vma_rd);
> +
> +	vma_wr = get_vma((unsigned long)user_buf_wr, user_len_wr);
> +	if (IS_ERR(vma_wr))
> +		return PTR_ERR(vma_wr);
> +
> +	sg_buf_rd = vma_rd->vm_private_data;
> +	sg_buf_wr = vma_wr->vm_private_data;
> +
> +	if ((sg_buf_rd->dma_dir != DMA_TO_DEVICE) ||
> +	    (sg_buf_wr->dma_dir != DMA_FROM_DEVICE))
> +		return -EINVAL;
> +
> +	dma_addr_rd = mem_base + vma_rd->vm_pgoff * PAGE_SIZE;
> +	dma_addr_wr = mem_base + vma_wr->vm_pgoff * PAGE_SIZE;
> +
> +	init_callback_info(&info, 2 * nr_dma_reps);
> +
> +	dma_sync_sg_for_device(dev,
> +			       sg_buf_rd->sgt.sgl,
> +			       sg_buf_rd->sgt.nents,
> +			       DMA_FROM_DEVICE);
> +	dma_sync_sg_for_device(dev,
> +			       sg_buf_wr->sgt.sgl,
> +			       sg_buf_wr->sgt.nents,
> +			       DMA_TO_DEVICE);
> +
> +	for (i = 0; i < nr_dma_reps; i++) {
> +		ret = submit_xfer_sg(chan, DMA_MEM_TO_DEV,
> +				     dma_addr_wr,
> +				     sg_buf_wr->sgt.sgl,
> +				     sg_buf_wr->sgt.nents,
> +				     xfer_callback, &info);
> +		if (ret)
> +			goto submit_err;
> +
> +		ret = submit_xfer_sg(chan, DMA_DEV_TO_MEM,
> +				     dma_addr_rd,
> +				     sg_buf_rd->sgt.sgl,
> +				     sg_buf_rd->sgt.nents,
> +				     xfer_callback, &info);
> +		if (ret)
> +			goto submit_err;
> +	}
> +
> +	dma_async_issue_pending(chan);
> +
> +	ret = wait_for_completion_interruptible(&info.completion);
> +
> +submit_err:
> +	dma_sync_sg_for_cpu(dev,
> +			    sg_buf_rd->sgt.sgl,
> +			    sg_buf_rd->sgt.nents,
> +			    DMA_DEV_TO_MEM);
> +	dma_sync_sg_for_cpu(dev,
> +			    sg_buf_wr->sgt.sgl,
> +			    sg_buf_wr->sgt.nents,
> +			    DMA_MEM_TO_DEV);
> +
> +	return ret;
> +}
> diff --git a/drivers/dma/avalon-test/avalon-xfer.h b/drivers/dma/avalon-test/avalon-xfer.h
> new file mode 100644
> index 000000000000..32bc6c0e7fc9
> --- /dev/null
> +++ b/drivers/dma/avalon-test/avalon-xfer.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + *
> + * Avalon DMA driver
> + */
> +#ifndef __AVALON_XFER_H__
> +#define __AVALON_XFER_H__
> +
> +#include <linux/dmaengine.h>
> +
> +#include "avalon-dev.h"
> +
> +int xfer_single(struct dma_chan *chan,
> +		enum dma_transfer_direction direction,
> +		void __user *user_buf, size_t user_len);
> +int xfer_rw_single(struct dma_chan *chan,
> +		   void __user *user_buf_rd, size_t user_len_rd,
> +		   void __user *user_buf_wr, size_t user_len_wr);
> +int xfer_sg(struct dma_chan *chan,
> +	    enum dma_transfer_direction direction,
> +	    void __user *user_buf, size_t user_len,
> +	    bool is_smp);
> +int xfer_rw_sg(struct dma_chan *chan,
> +	       void __user *user_buf_rd, size_t user_len_rd,
> +	       void __user *user_buf_wr, size_t user_len_wr);
> +
> +#endif
> diff --git a/include/uapi/linux/avalon-ioctl.h b/include/uapi/linux/avalon-ioctl.h
> new file mode 100644
> index 000000000000..a42d7b4bc0a2
> --- /dev/null
> +++ b/include/uapi/linux/avalon-ioctl.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/*
> + * Avalon DMA driver
> + *
> + * Author: Alexander Gordeev <a.gordeev.box@gmail.com>
> + */
> +#ifndef _UAPI_LINUX_AVALON_IOCTL_H__
> +#define _UAPI_LINUX_AVALON_IOCTL_H__
> +
> +#include <linux/types.h>
> +
> +#define AVALON_DEVICE_NAME		"avalon-dev"
> +
> +struct avalon_dma_info {
> +	size_t mem_addr;
> +	size_t mem_size;
> +	size_t dma_size;
> +	size_t dma_size_sg;
> +} __attribute((packed));
> +
> +#define AVALON_SIG 'V'
> +
> +#define IOCTL_AVALON_DMA_GET_INFO	_IOR(AVALON_SIG, 0, struct avalon_dma_info)
> +#define IOCTL_AVALON_DMA_SET_INFO	_IOW(AVALON_SIG, 1, struct avalon_dma_info)
> +#define IOCTL_AVALON_DMA_READ		_IOR(AVALON_SIG, 2, struct iovec)
> +#define IOCTL_AVALON_DMA_WRITE		_IOW(AVALON_SIG, 3, struct iovec)
> +#define IOCTL_AVALON_DMA_RDWR		_IOWR(AVALON_SIG, 4, struct iovec[2])
> +#define IOCTL_AVALON_DMA_READ_SG	_IOR(AVALON_SIG, 5, struct iovec)
> +#define IOCTL_AVALON_DMA_WRITE_SG	_IOW(AVALON_SIG, 6, struct iovec)
> +#define IOCTL_AVALON_DMA_RDWR_SG	_IOWR(AVALON_SIG, 7, struct iovec[2])
> +#define IOCTL_AVALON_DMA_READ_SG_SMP	_IOR(AVALON_SIG, 8, struct iovec)
> +#define IOCTL_AVALON_DMA_WRITE_SG_SMP	_IOW(AVALON_SIG, 9, struct iovec)
> +
> +#endif
> -- 
> 2.24.0

-- 
~Vinod

Re: [PATCH RFC v5 2/2] dmaengine: avalon-test: Intel Avalon-MM DMA Interface for PCIe test

[Alexander Gordeev]

On Thu, Nov 14, 2019 at 10:33:31AM +0530, Vinod Koul wrote:
> On 06-11-19, 20:22, Alexander Gordeev wrote:
> > This is a sample implementation of a driver using "avalon-dma" to
> > perform data transfers between target device memory and system memory:
> > 
> >     +----------+    +----------+            +----------+
> >     |   RAM    |<-->|  Avalon  |<---PCIe--->|   Host   |
> >     +----------+    +----------+            +----------+
> >
> > The target device is expected to use only Avalon-MM DMA Interface for
> > PCIe to initiate DMA transactions - without custom hardware specifics
> > to make such transfers possible.
> > 
> > Unlike "dmatest" driver, the contents of DMAed data is not manipulated by
> > "avalon-test" in any way. It is basically pass-through and the the data
> > are fully dependent on the target device implementation. Thus, it is up
> > to the users to analyze received or provide meaningful transmitted data.
> 
> Is this the only reason why you have not used dmatest. If so, why not
> add the feature to dmatest to optionally not check the DMAed data
> contents?

The main reason is that "dmatest" does not support DMA_SLAVE type of
transactions.

I considered adding DMA_SLAVE to "dmatest". But it would break the 
current neat design and does not appear solving the issue of data
verification. Simply besause in general DMA_SLAVE case there is no
data integrity criteria easily available to the driver. I.e if the
data is a sensor image then verifying it in the driver would be
pointless.

So in case of "avalon-test" I offloaded the task of data verification
to the user. The driver itself just streams user data to/from device.

In fact, this approach is not "avalon-dma" specific and could be used
with any "dmaengine" compatible driver. Moreover, it would be quite
useful for bringing up devices in embedded systems. I.e one could
master a raw display frame in user space and DMA it via the driver -
without graphic stack involved.

The only missing functionality I could think of is using DMABUFs, but that
is very easy to add.

Actually, "avalon-test" is rather a presentation of how I tested
"avalon-dma". I understand "dmatest" is more easy to trust and I could
probably make it working with DMA_SLAVE type. But that would entail
hardware design requirements:

  - DMA slave should both respond to read and write transactions;
  - data read should always be the same as data written;

I have such version of hardware design, but I doubt majorify of devices
out there can honor the above requirements. 

Summarizing - I would suggest not to change "dmatest" and bring in a
generalized version of "avalon-test" if you find it useful for a wider
audience.

Thanks!

> -- 
> ~Vinod

Re: [PATCH RFC v5 2/2] dmaengine: avalon-test: Intel Avalon-MM DMA Interface for PCIe test

[Vinod Koul]

On 14-11-19, 16:53, Alexander Gordeev wrote:
> On Thu, Nov 14, 2019 at 10:33:31AM +0530, Vinod Koul wrote:
> > On 06-11-19, 20:22, Alexander Gordeev wrote:
> > > This is a sample implementation of a driver using "avalon-dma" to
> > > perform data transfers between target device memory and system memory:
> > > 
> > >     +----------+    +----------+            +----------+
> > >     |   RAM    |<-->|  Avalon  |<---PCIe--->|   Host   |
> > >     +----------+    +----------+            +----------+
> > >
> > > The target device is expected to use only Avalon-MM DMA Interface for
> > > PCIe to initiate DMA transactions - without custom hardware specifics
> > > to make such transfers possible.
> > > 
> > > Unlike "dmatest" driver, the contents of DMAed data is not manipulated by
> > > "avalon-test" in any way. It is basically pass-through and the the data
> > > are fully dependent on the target device implementation. Thus, it is up
> > > to the users to analyze received or provide meaningful transmitted data.
> > 
> > Is this the only reason why you have not used dmatest. If so, why not
> > add the feature to dmatest to optionally not check the DMAed data
> > contents?
> 
> The main reason is that "dmatest" does not support DMA_SLAVE type of
> transactions.

That is correct, but it can be added!

> I considered adding DMA_SLAVE to "dmatest". But it would break the 
> current neat design and does not appear solving the issue of data
> verification. Simply besause in general DMA_SLAVE case there is no

Am not sure why it break the current design. We have to skip the
verification part. It would not only help you but also other to have
this support in dmatest

> data integrity criteria easily available to the driver. I.e if the
> data is a sensor image then verifying it in the driver would be
> pointless.

The biggest issue with slave and dmatest is how to setup slave

> So in case of "avalon-test" I offloaded the task of data verification
> to the user. The driver itself just streams user data to/from device.
> 
> In fact, this approach is not "avalon-dma" specific and could be used
> with any "dmaengine" compatible driver. Moreover, it would be quite
> useful for bringing up devices in embedded systems. I.e one could
> master a raw display frame in user space and DMA it via the driver -
> without graphic stack involved.

Right and having it in dmatest makes more sense for everyone :)

> The only missing functionality I could think of is using DMABUFs, but that
> is very easy to add.
> 
> Actually, "avalon-test" is rather a presentation of how I tested
> "avalon-dma". I understand "dmatest" is more easy to trust and I could
> probably make it working with DMA_SLAVE type. But that would entail
> hardware design requirements:
> 
>   - DMA slave should both respond to read and write transactions;
>   - data read should always be the same as data written;
> 
> I have such version of hardware design, but I doubt majorify of devices
> out there can honor the above requirements. 
> 
> Summarizing - I would suggest not to change "dmatest" and bring in a
> generalized version of "avalon-test" if you find it useful for a wider
> audience.

I would still think adding to dmatest makes more sense!

-- 
~Vinod