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Date:   Sun, 4 Sep 2022 22:26:58 +0530
From:   Vinod Koul <vkoul@kernel.org>
To:     Lizhi Hou <lizhi.hou@amd.com>
Cc:     dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
        max.zhen@amd.com, sonal.santan@amd.com, larry.liu@amd.com,
        brian.xu@amd.com, trix@redhat.com
Subject: Re: [RESEND PATCH V1 XDMA 1/1] dmaengine: xilinx: xdma: add xilinx
 xdma driver
Message-ID: <YxTY2llOkiUoyFW2@matsya>
References: <1660171522-64983-1-git-send-email-lizhi.hou@amd.com>
 <1660171522-64983-2-git-send-email-lizhi.hou@amd.com>
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In-Reply-To: <1660171522-64983-2-git-send-email-lizhi.hou@amd.com>
Precedence: bulk

On 10-08-22, 15:45, Lizhi Hou wrote:
> Add driver to enable PCIe board which uses XDMA (the DMA/Bridge Subsystem
> for PCI Express). For example, Xilinx Alveo PCIe devices.
>     https://www.xilinx.com/products/boards-and-kits/alveo.html
> 
> The XDMA engine support up to 4 Host to Card (H2C) and 4 Card to Host (C2H)
> channels. Memory transfers are specified on a per-channel basis in
> descriptor linked lists, which the DMA fetches from host memory and
> processes. Events such as descriptor completion and errors are signaled
> using interrupts. The hardware detail is provided by
>     https://docs.xilinx.com/r/en-US/pg195-pcie-dma/Introduction
> 
> This driver implements dmaengine APIs.
>     - probe the available DMA channels
>     - use dma_slave_map for channel lookup
>     - use virtual channel to manage dmaengine tx descriptors
>     - implement device_prep_slave_sg callback to handle host scatter gather
>       list
>     - implement device_config to config device address for DMA transfer
> 
> Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
> Signed-off-by: Sonal Santan <sonal.santan@amd.com>
> Signed-off-by: Max Zhen <max.zhen@amd.com>
> Signed-off-by: Brian Xu <brian.xu@amd.com>
> ---
>  MAINTAINERS                            |  10 +
>  drivers/dma/Kconfig                    |  13 +
>  drivers/dma/xilinx/Makefile            |   1 +
>  drivers/dma/xilinx/xdma-regs.h         | 179 +++++
>  drivers/dma/xilinx/xdma.c              | 952 +++++++++++++++++++++++++
>  include/linux/platform_data/amd_xdma.h |  34 +
>  6 files changed, 1189 insertions(+)
>  create mode 100644 drivers/dma/xilinx/xdma-regs.h
>  create mode 100644 drivers/dma/xilinx/xdma.c
>  create mode 100644 include/linux/platform_data/amd_xdma.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e8c52d0192a6..400055e3a725 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21683,6 +21683,16 @@ F:	Documentation/devicetree/bindings/media/xilinx/
>  F:	drivers/media/platform/xilinx/
>  F:	include/uapi/linux/xilinx-v4l2-controls.h
>  
> +XILINX XDMA DRIVER
> +M:	Lizhi Hou <lizhi.hou@amd.com>
> +M:	Brian Xu <brian.xu@amd.com>
> +M:	Raj Kumar Rampelli <raj.kumar.rampelli@amd.com>
> +L:	dmaengine@vger.kernel.org
> +S:	Supported
> +F:	drivers/dma/xilinx/xdma-regs.h
> +F:	drivers/dma/xilinx/xdma.c
> +F:	include/linux/platform_data/xdma.h
> +
>  XILINX ZYNQMP DPDMA DRIVER
>  M:	Hyun Kwon <hyun.kwon@xilinx.com>
>  M:	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index d5de3f77d3aa..4d90f2f51655 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -733,6 +733,19 @@ config XILINX_ZYNQMP_DPDMA
>  	  driver provides the dmaengine required by the DisplayPort subsystem
>  	  display driver.
>  
> +config XILINX_XDMA
> +	tristate "Xilinx DMA/Bridge Subsystem DMA Engine"
> +	select DMA_ENGINE
> +	select DMA_VIRTUAL_CHANNELS
> +	select REGMAP_MMIO
> +	help
> +	  Enable support for Xilinx DMA/Bridge Subsystem DMA engine. The DMA
> +	  provides high performance block data movement between Host memory
> +	  and the DMA subsystem. These direct memory transfers can be both in
> +	  the Host to Card (H2C) and Card to Host (C2H) transfers.
> +	  The core also provides up to 16 user interrupt wires that generate
> +	  interrupts to the host.
> +
>  # driver files
>  source "drivers/dma/bestcomm/Kconfig"
>  
> diff --git a/drivers/dma/xilinx/Makefile b/drivers/dma/xilinx/Makefile
> index 767bb45f641f..c7a538a56643 100644
> --- a/drivers/dma/xilinx/Makefile
> +++ b/drivers/dma/xilinx/Makefile
> @@ -2,3 +2,4 @@
>  obj-$(CONFIG_XILINX_DMA) += xilinx_dma.o
>  obj-$(CONFIG_XILINX_ZYNQMP_DMA) += zynqmp_dma.o
>  obj-$(CONFIG_XILINX_ZYNQMP_DPDMA) += xilinx_dpdma.o
> +obj-$(CONFIG_XILINX_XDMA) += xdma.o
> diff --git a/drivers/dma/xilinx/xdma-regs.h b/drivers/dma/xilinx/xdma-regs.h
> new file mode 100644
> index 000000000000..2296dfb90a8b
> --- /dev/null
> +++ b/drivers/dma/xilinx/xdma-regs.h
> @@ -0,0 +1,179 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2017-2020 Xilinx, Inc. All rights reserved.
> + * Copyright (C) 2022 Advanced Micro Devices, Inc. All rights reserved.
> + */
> +
> +#ifndef __DMA_XDMA_REGS_H
> +#define __DMA_XDMA_REGS_H
> +
> +/* The length of register space exposed to host */
> +#define XDMA_REG_SPACE_LEN	65536
> +
> +/*
> + * maximum number of DMA channels for each direction:
> + * Host to Card (H2C) or Card to Host (C2H)
> + */
> +#define XDMA_MAX_CHANNELS	4
> +
> +/* macros to get higher and lower 32-bit address */
> +#define XDMA_ADDR_H(addr)	((u64)(addr) >> 32)
> +#define XDMA_ADDR_L(addr)	((u64)(addr) & 0xffffffffUL)

Pls use kernel macros instead please

> +
> +/*
> + * macros to define the number of descriptor blocks can be used in one
> + * DMA transfer request.
> + * the DMA engine uses a linked list of descriptor blocks that specify the
> + * source, destination, and length of the DMA transfers.
> + */
> +#define XDMA_DESC_BLOCK_NUM		BIT(7)
> +#define XDMA_DESC_BLOCK_MASK		(XDMA_DESC_BLOCK_NUM - 1)
> +
> +/* descriptor definitions */
> +#define XDMA_DESC_ADJACENT		BIT(5)
> +#define XDMA_DESC_MAGIC			0xad4bUL
> +#define XDMA_DESC_MAGIC_SHIFT		16
> +#define XDMA_DESC_ADJACENT_SHIFT	8
> +#define XDMA_DESC_STOPPED		BIT(0)
> +#define XDMA_DESC_COMPLETED		BIT(1)
> +#define XDMA_DESC_BLEN_BITS		28
> +#define XDMA_DESC_BLEN_MAX		(BIT(XDMA_DESC_BLEN_BITS) - PAGE_SIZE)
> +
> +/* macros to construct the descriptor control word */
> +#define XDMA_DESC_CONTROL(adjacent, flag)				\
> +	((XDMA_DESC_MAGIC << XDMA_DESC_MAGIC_SHIFT) |			\
> +	 (((adjacent) - 1) << XDMA_DESC_ADJACENT_SHIFT) | (flag))
> +#define XDMA_DESC_CONTROL_LAST						\
> +	XDMA_DESC_CONTROL(1, XDMA_DESC_STOPPED | XDMA_DESC_COMPLETED)
> +
> +/*
> + * Descriptor for a single contiguous memory block transfer.
> + *
> + * Multiple descriptors are linked by means of the next pointer. An additional
> + * extra adjacent number gives the amount of extra contiguous descriptors.
> + *
> + * The descriptors are in root complex memory, and the bytes in the 32-bit
> + * words must be in little-endian byte ordering.
> + */
> +enum xdma_desc_field {
> +	XDMA_DF_CONTROL,
> +	XDMA_DF_BYTES,		/* transfer length in bytes */
> +	XDMA_DF_SRC_ADDR_LO,	/* source address (low 32-bit) */
> +	XDMA_DF_SRC_ADDR_HI,	/* source address (high 32-bit) */
> +	XDMA_DF_DST_ADDR_LO,	/* destination address (low 32-bit) */
> +	XDMA_DF_DST_ADDR_HI,	/* destination address (high 32-bit) */
> +	/*
> +	 * next descriptor in the single-linked list of descriptors;
> +	 * this is the PCIe (bus) address of the next descriptor in the
> +	 * root complex memory
> +	 */
> +	XDMA_DF_NEXT_LO,	/* next desc address (low 32-bit) */
> +	XDMA_DF_NEXT_HI,	/* next desc address (high 32-bit) */
> +	XDMA_DF_NUM
> +};
> +
> +#define XDMA_DF_SZ		4
> +#define XDMA_DESC_SIZE		(XDMA_DF_NUM * XDMA_DF_SZ)
> +#define XDMA_DESC_BLOCK_SIZE	(XDMA_DESC_SIZE * XDMA_DESC_ADJACENT)
> +
> +/*
> + * Channel registers
> + */
> +#define XDMA_CHAN_IDENTIFIER		0x0
> +#define XDMA_CHAN_CONTROL		0x4
> +#define XDMA_CHAN_CONTROL_W1S		0x8
> +#define XDMA_CHAN_CONTROL_W1C		0xc
> +#define XDMA_CHAN_STATUS		0x40
> +#define XDMA_CHAN_COMPLETED_DESC	0x48
> +#define XDMA_CHAN_ALIGNMENTS		0x4c
> +#define XDMA_CHAN_INTR_ENABLE		0x90
> +#define XDMA_CHAN_INTR_ENABLE_W1S	0x94
> +#define XDMA_CHAN_INTR_ENABLE_W1C	0x9c
> +
> +#define XDMA_CHAN_STRIDE	0x100
> +#define XDMA_CHAN_H2C_OFFSET	0x0
> +#define XDMA_CHAN_C2H_OFFSET	0x1000
> +#define XDMA_CHAN_H2C_TARGET	0x0
> +#define XDMA_CHAN_C2H_TARGET	0x1
> +
> +/* macro to check if channel is available */
> +#define XDMA_CHAN_MAGIC		0x1fc0
> +#define XDMA_CHAN_CHECK_TARGET(id, target)		\
> +	(((u32)(id) >> 16) == XDMA_CHAN_MAGIC + (target))
> +
> +/* bits of the channel control register */
> +#define CHAN_CTRL_RUN_STOP			BIT(0)
> +#define CHAN_CTRL_IE_DESC_STOPPED		BIT(1)
> +#define CHAN_CTRL_IE_DESC_COMPLETED		BIT(2)
> +#define CHAN_CTRL_IE_DESC_ALIGN_MISMATCH	BIT(3)
> +#define CHAN_CTRL_IE_MAGIC_STOPPED		BIT(4)
> +#define CHAN_CTRL_IE_IDLE_STOPPED		BIT(6)
> +#define CHAN_CTRL_IE_READ_ERROR			(0x1FUL << 9)
> +#define CHAN_CTRL_IE_DESC_ERROR			(0x1FUL << 19)
> +#define CHAN_CTRL_NON_INCR_ADDR			BIT(25)
> +#define CHAN_CTRL_POLL_MODE_WB			BIT(26)
> +
> +#define CHAN_CTRL_START	(CHAN_CTRL_RUN_STOP |				\
> +			 CHAN_CTRL_IE_DESC_STOPPED |			\
> +			 CHAN_CTRL_IE_DESC_COMPLETED |			\
> +			 CHAN_CTRL_IE_DESC_ALIGN_MISMATCH |		\
> +			 CHAN_CTRL_IE_MAGIC_STOPPED |			\
> +			 CHAN_CTRL_IE_READ_ERROR |			\
> +			 CHAN_CTRL_IE_DESC_ERROR)
> +
> +/* bits of the channel interrupt enable mask */
> +#define CHAN_IM_DESC_ERROR			BIT(19)
> +#define CHAN_IM_READ_ERROR			BIT(9)
> +#define CHAN_IM_IDLE_STOPPED			BIT(6)
> +#define CHAN_IM_MAGIC_STOPPED			BIT(4)
> +#define CHAN_IM_DESC_COMPLETED			BIT(2)
> +#define CHAN_IM_DESC_STOPPED			BIT(1)
> +
> +#define CHAN_IM_ALL	(CHAN_IM_DESC_ERROR | CHAN_IM_READ_ERROR |	\
> +			 CHAN_IM_IDLE_STOPPED | CHAN_IM_MAGIC_STOPPED | \
> +			 CHAN_IM_DESC_COMPLETED | CHAN_IM_DESC_STOPPED)
> +
> +/*
> + * Channel SGDMA registers
> + */
> +#define XDMA_SGDMA_IDENTIFIER	0x0
> +#define XDMA_SGDMA_DESC_LO	0x80
> +#define XDMA_SGDMA_DESC_HI	0x84
> +#define XDMA_SGDMA_DESC_ADJ	0x88
> +#define XDMA_SGDMA_DESC_CREDIT	0x8c
> +
> +#define XDMA_SGDMA_BASE(chan_base)	((chan_base) + 0x4000)
> +
> +/* bits of the SG DMA control register */
> +#define XDMA_CTRL_RUN_STOP			BIT(0)
> +#define XDMA_CTRL_IE_DESC_STOPPED		BIT(1)
> +#define XDMA_CTRL_IE_DESC_COMPLETED		BIT(2)
> +#define XDMA_CTRL_IE_DESC_ALIGN_MISMATCH	BIT(3)
> +#define XDMA_CTRL_IE_MAGIC_STOPPED		BIT(4)
> +#define XDMA_CTRL_IE_IDLE_STOPPED		BIT(6)
> +#define XDMA_CTRL_IE_READ_ERROR			(0x1FUL << 9)
> +#define XDMA_CTRL_IE_DESC_ERROR			(0x1FUL << 19)
> +#define XDMA_CTRL_NON_INCR_ADDR			BIT(25)
> +#define XDMA_CTRL_POLL_MODE_WB			BIT(26)
> +
> +/*
> + * interrupt registers
> + */
> +#define XDMA_IRQ_IDENTIFIER		0x0
> +#define XDMA_IRQ_USER_INT_EN		0x04
> +#define XDMA_IRQ_USER_INT_EN_W1S	0x08
> +#define XDMA_IRQ_USER_INT_EN_W1C	0x0c
> +#define XDMA_IRQ_CHAN_INT_EN		0x10
> +#define XDMA_IRQ_CHAN_INT_EN_W1S	0x14
> +#define XDMA_IRQ_CHAN_INT_EN_W1C	0x18
> +#define XDMA_IRQ_USER_INT_REQ		0x40
> +#define XDMA_IRQ_CHAN_INT_REQ		0x44
> +#define XDMA_IRQ_USER_INT_PEND		0x48
> +#define XDMA_IRQ_CHAN_INT_PEND		0x4c
> +#define XDMA_IRQ_USER_VEC_NUM		0x80
> +#define XDMA_IRQ_CHAN_VEC_NUM		0xa0
> +
> +#define XDMA_IRQ_BASE			0x2000
> +#define XDMA_IRQ_VEC_SHIFT		8
> +
> +#endif /* __DMA_XDMA_REGS_H */
> diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
> new file mode 100644
> index 000000000000..68116217549e
> --- /dev/null
> +++ b/drivers/dma/xilinx/xdma.c
> @@ -0,0 +1,952 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * DMA driver for Xilinx DMA/Bridge Subsystem
> + *
> + * Copyright (C) 2017-2020 Xilinx, Inc. All rights reserved.
> + * Copyright (C) 2022 Advanced Micro Devices, Inc. All rights reserved.
> + */
> +
> +/*
> + * The DMA/Bridge Subsystem for PCI Express allows for the movement of data
> + * between Host memory and the DMA subsystem. It does this by operating on
> + * 'descriptors' that contain information about the source, destination and
> + * amount of data to transfer. These direct memory transfers can be both in
> + * the Host to Card (H2C) and Card to Host (C2H) transfers. The DMA can be
> + * configured to have a single AXI4 Master interface shared by all channels
> + * or one AXI4-Stream interface for each channel enabled. Memory transfers are
> + * specified on a per-channel basis in descriptor linked lists, which the DMA
> + * fetches from host memory and processes. Events such as descriptor completion
> + * and errors are signaled using interrupts. The core also provides up to 16
> + * user interrupt wires that generate interrupts to the host.
> + */
> +
> +#include <linux/mod_devicetable.h>
> +#include <linux/regmap.h>
> +#include <linux/dmaengine.h>
> +#include <linux/platform_device.h>
> +#include <linux/platform_data/amd_xdma.h>
> +#include <linux/dma-mapping.h>
> +#include "../virt-dma.h"
> +#include "xdma-regs.h"
> +
> +/* mmio regmap config for all XDMA registers */
> +static const struct regmap_config xdma_regmap_config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.max_register = XDMA_REG_SPACE_LEN,
> +};
> +
> +/**
> + * struct xdma_desc_block - Descriptor block
> + * @virt_addr: Virtual address of block start
> + * @dma_addr: DMA address of block start
> + * @desc_num: Number of descriptors in the block
> + */
> +struct xdma_desc_block {
> +	void		*virt_addr;
> +	dma_addr_t	dma_addr;
> +	u32		desc_num;
> +};
> +
> +/**
> + * struct xdma_chan - Driver specific DMA channel structure
> + * @vchan: Virtual channel
> + * @xdev_hdl: Pointer to DMA device structure
> + * @base: Offset of channel registers
> + * @desc_blocks: Descriptor blocks
> + * @busy: Busy flag of the channel
> + * @dir: Transferring direction of the channel
> + * @dev_addr_field: Descriptor field for device address
> + * @host_addr_field: Descriptor field for host address
> + * @cfg: Transferring config of the channel
> + * @irq: IRQ assigned to the channel
> + * @tasklet: Channel tasklet
> + */
> +struct xdma_chan {
> +	struct virt_dma_chan		vchan;
> +	void				*xdev_hdl;
> +	u32				base;
> +	struct xdma_desc_block		desc_blocks[XDMA_DESC_BLOCK_NUM];
> +	bool				busy;
> +	enum dma_transfer_direction	dir;
> +	enum xdma_desc_field		dev_addr_field;
> +	enum xdma_desc_field		host_addr_field;
> +	struct dma_slave_config		cfg;
> +	u32				irq;
> +	struct tasklet_struct		tasklet;
> +};
> +
> +/**
> + * struct xdma_request - DMA request structure
> + * @vdesc: Virtual DMA descriptor
> + * @dir: Transferring direction of the request
> + * @dev_addr: Physical address on DMA device side
> + * @sgl: Scatter gather list on host side
> + * @sg_off: Start offset of the first sgl segment
> + * @nents: Number of sgl segments to transfer
> + */
> +struct xdma_request {
> +	struct virt_dma_desc		vdesc;
> +	enum dma_transfer_direction	dir;
> +	u64				dev_addr;
> +	struct scatterlist		*sgl;
> +	u32				sg_off;
> +	u32				nents;
> +};
> +
> +#define XDMA_DEV_STATUS_REG_DMA		BIT(0)
> +#define XDMA_DEV_STATUS_INIT_MSIX	BIT(1)
> +
> +/**
> + * struct xdma_device - DMA device structure
> + * @pdev: Platform device pointer
> + * @dma_dev: DMA device structure
> + * @regmap: MMIO regmap for DMA registers
> + * @h2c_chans: Host to Card channels
> + * @c2h_chans: Card to Host channels
> + * @h2c_chan_num: Number of H2C channels
> + * @c2h_chan_num: Number of C2H channels
> + * @irq_start: Start IRQ assigned to device
> + * @irq_num: Number of IRQ assigned to device
> + * @status: Initialization status
> + */
> +struct xdma_device {
> +	struct platform_device	*pdev;
> +	struct dma_device	dma_dev;
> +	struct regmap		*regmap;
> +	struct xdma_chan	*h2c_chans;
> +	struct xdma_chan	*c2h_chans;
> +	u32			h2c_chan_num;
> +	u32			c2h_chan_num;
> +	u32			irq_start;
> +	u32			irq_num;
> +	u32			status;
> +};
> +
> +/* Read and Write DMA registers */
> +static inline int xdma_read_reg(struct xdma_device *xdev, u32 base, u32 reg,
> +				u32 *val)

this can be a single line

> +{
> +	return regmap_read(xdev->regmap, base + reg, val);
> +}
> +
> +static inline int xdma_write_reg(struct xdma_device *xdev, u32 base, u32 reg,
> +				 u32 val)
> +{
> +	return regmap_write(xdev->regmap, base + reg, val);
> +}
> +
> +/* Write specified word of DMA descriptor */
> +static inline void xdma_desc_set_field(void *desc, enum xdma_desc_field field,
> +				       u32 val)
> +{
> +	*((__le32 *)desc + field) = cpu_to_le32(val);

What is the reason for this cast.. why not use proper data type for desc
instead of desc


> +}
> +
> +/**
> + * xdma_desc_set - fill DMA descriptor
> + * @xdma_chan: DMA channel pointer
> + * @desc: Descriptor pointer
> + * @addr: Physical address on host side
> + * @dev_addr: Physical address on DMA device side
> + * @len: Data length
> + */
> +static void xdma_desc_set(struct xdma_chan *xdma_chan, void *desc,
> +			  dma_addr_t addr, u64 dev_addr, u32 len)
> +{
> +	xdma_desc_set_field(desc, XDMA_DF_CONTROL, XDMA_DESC_CONTROL(1, 0));
> +	xdma_desc_set_field(desc, XDMA_DF_BYTES, len);
> +	xdma_desc_set_field(desc, XDMA_DF_NEXT_LO, 0);
> +	xdma_desc_set_field(desc, XDMA_DF_NEXT_HI, 0);
> +
> +	xdma_desc_set_field(desc, xdma_chan->dev_addr_field,
> +			    XDMA_ADDR_L(dev_addr));
> +	xdma_desc_set_field(desc, xdma_chan->dev_addr_field + 1,
> +			    XDMA_ADDR_H(dev_addr));
> +	xdma_desc_set_field(desc, xdma_chan->host_addr_field,
> +			    XDMA_ADDR_L(addr));
> +	xdma_desc_set_field(desc, xdma_chan->host_addr_field + 1,
> +			    XDMA_ADDR_H(addr));
> +}
> +
> +/**
> + * xdma_link_desc_blocks - Link descriptor blocks for DMA transfer
> + * @num_blocks: Number of descriptors to link
> + */
> +static void xdma_link_desc_blocks(struct xdma_chan *xdma_chan, u32 num_blocks)
> +{
> +	struct xdma_desc_block *block, *next_block;
> +	void *desc;
> +	int i;
> +
> +	for (i = 0; i < num_blocks - 1; i++) {
> +		block = &xdma_chan->desc_blocks[i];
> +		next_block = &xdma_chan->desc_blocks[i + 1];
> +
> +		desc = block->virt_addr + (block->desc_num - 1) *
> +			XDMA_DESC_SIZE;
> +
> +		xdma_desc_set_field(desc, XDMA_DF_CONTROL,
> +				    XDMA_DESC_CONTROL(next_block->desc_num, 0));
> +		xdma_desc_set_field(desc, XDMA_DF_NEXT_LO,
> +				    XDMA_ADDR_L(next_block->dma_addr));
> +		xdma_desc_set_field(desc, XDMA_DF_NEXT_HI,
> +				    XDMA_ADDR_H(next_block->dma_addr));
> +	}
> +}
> +
> +static inline struct xdma_chan *to_xdma_chan(struct dma_chan *chan)
> +{
> +	return container_of(chan, struct xdma_chan, vchan.chan);
> +}
> +
> +static inline struct xdma_request *to_xdma_req(struct virt_dma_desc *vdesc)
> +{
> +	return container_of(vdesc, struct xdma_request, vdesc);
> +}
> +
> +static int xdma_enable_intr(struct xdma_device *xdev)
> +{
> +	int ret;
> +
> +	ret = xdma_write_reg(xdev, XDMA_IRQ_BASE, XDMA_IRQ_CHAN_INT_EN_W1S, ~0);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "set channel intr mask failed: %d",
> +			ret);
> +	}

single line and pls get rid of braces here

> +
> +	return ret;
> +}
> +
> +static int xdma_disable_intr(struct xdma_device *xdev)
> +{
> +	int ret;
> +
> +	ret = xdma_write_reg(xdev, XDMA_IRQ_BASE, XDMA_IRQ_CHAN_INT_EN_W1C, ~0);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "clear channel intr mask failed: %d",
> +			ret);
> +	}

Here too and other places


> +
> +	return ret;
> +}
> +
> +/**
> + * xdma_channel_init - Initialize DMA channel registers
> + * @chan: DMA channel pointer
> + */
> +static int xdma_channel_init(struct xdma_chan *chan)
> +{
> +	struct xdma_device *xdev = chan->xdev_hdl;
> +	int ret;
> +
> +	ret = xdma_write_reg(xdev, chan->base, XDMA_CHAN_CONTROL_W1C,
> +			     CHAN_CTRL_NON_INCR_ADDR);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "failed to clear non incr addr: %d",
> +			ret);
> +		return ret;
> +	}
> +
> +	ret = xdma_write_reg(xdev, chan->base, XDMA_CHAN_INTR_ENABLE,
> +			     CHAN_IM_ALL);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "failed to set interrupt mask: %d",
> +			ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void xdma_free_tx_desc(struct virt_dma_desc *vdesc)
> +{
> +	struct xdma_request *req;
> +
> +	req = to_xdma_req(vdesc);
> +	kfree(req);
> +}
> +
> +/**
> + * xdma_xfer_start - Start DMA transfer
> + * @xdma_chan: DMA channel pointer
> + */
> +static int xdma_xfer_start(struct xdma_chan *xdma_chan)
> +{
> +	struct virt_dma_desc *vd = vchan_next_desc(&xdma_chan->vchan);
> +	struct xdma_device *xdev = xdma_chan->xdev_hdl;
> +	u32 i, rest, len, sg_off, desc_num = 0;
> +	struct xdma_desc_block *block;
> +	struct xdma_request *req;
> +	struct scatterlist *sg;
> +	void *last_desc = NULL;
> +	u64 dev_addr;
> +	dma_addr_t addr;
> +	int ret;
> +
> +	/*
> +	 * check if there is not any submitted descriptor or channel is busy.
> +	 * vchan lock should be held where this function is called.
> +	 */
> +	if (!vd || xdma_chan->busy)
> +		return -EINVAL;
> +
> +	/* clear run stop bit to get ready for transfer */
> +	ret = xdma_write_reg(xdev, xdma_chan->base, XDMA_CHAN_CONTROL_W1C,
> +			     CHAN_CTRL_RUN_STOP);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "write control failed: %d", ret);
> +		return ret;
> +	}
> +
> +	req = to_xdma_req(vd);
> +	if (req->dir != xdma_chan->dir) {
> +		dev_err(&xdev->pdev->dev, "incorrect request direction");
> +		return -EINVAL;
> +	}
> +
> +	sg = req->sgl;
> +	sg_off = req->sg_off;
> +	dev_addr = req->dev_addr;
> +
> +	/*
> +	 * submit sgl segments to hardware. complete submission either
> +	 * all descriptors are used or all segments are submitted.
> +	 */
> +	for (i = 0; i < XDMA_DESC_BLOCK_NUM && req->nents && sg; i++) {
> +		void *desc;
> +
> +		block = &xdma_chan->desc_blocks[i];
> +		desc = block->virt_addr;
> +
> +		/* set descriptor block */
> +		while (desc_num < XDMA_DESC_ADJACENT && sg) {
> +			addr = sg_dma_address(sg) + sg_off;
> +			rest = sg_dma_len(sg) - sg_off;
> +
> +			/*
> +			 * if the rest of segment greater than the maximum
> +			 * data block can be sent by a hardware descriptor
> +			 */
> +			if (rest > XDMA_DESC_BLEN_MAX) {
> +				len = XDMA_DESC_BLEN_MAX;
> +				sg_off += XDMA_DESC_BLEN_MAX;
> +			} else {
> +				len = rest;
> +				sg_off = 0;
> +				sg = sg_next(sg);
> +				req->nents--;
> +			}
> +
> +			/* skip the zero length segment */
> +			if (!len)
> +				continue;
> +
> +			/* set hardware descriptor */
> +			xdma_desc_set(xdma_chan, desc, addr, dev_addr,
> +				      len);
> +			last_desc = desc;
> +			desc += XDMA_DESC_SIZE;
> +			desc_num++;
> +		}
> +		block->desc_num = desc_num;
> +		desc_num = 0;
> +	}
> +	if (!last_desc) {
> +		dev_err(&xdev->pdev->dev, "invalid sgl");
> +		return -EINVAL;
> +	}
> +
> +	/* link all descriptors for transferring */
> +	xdma_link_desc_blocks(xdma_chan, i);
> +
> +	/* record the rest of sgl */
> +	req->sgl = sg;
> +	req->sg_off = sg_off;
> +
> +	/* set control word of last descriptor */
> +	xdma_desc_set_field(last_desc, XDMA_DF_CONTROL, XDMA_DESC_CONTROL_LAST);
> +
> +	/* set DMA engine to the first descriptor block */
> +	block = &xdma_chan->desc_blocks[0];
> +	ret = xdma_write_reg(xdev, XDMA_SGDMA_BASE(xdma_chan->base),
> +			     XDMA_SGDMA_DESC_LO,
> +			     XDMA_ADDR_L(block->dma_addr));
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "write hi addr failed: %d", ret);
> +		return ret;
> +	}
> +
> +	ret = xdma_write_reg(xdev, XDMA_SGDMA_BASE(xdma_chan->base),
> +			     XDMA_SGDMA_DESC_HI,
> +			     XDMA_ADDR_H(block->dma_addr));
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "write lo addr failed: %d", ret);
> +		return ret;
> +	}
> +
> +	ret = xdma_write_reg(xdev, XDMA_SGDMA_BASE(xdma_chan->base),
> +			     XDMA_SGDMA_DESC_ADJ, block->desc_num - 1);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "write adjacent failed: %d", ret);
> +		return ret;
> +	}

That is a lot of work for dma start :-(

You should keep everything pre calculated in prep_ call and write to
registers here and kick off dma

> +
> +	/* kick off DMA transfer */
> +	ret = xdma_write_reg(xdev, xdma_chan->base, XDMA_CHAN_CONTROL,
> +			     CHAN_CTRL_START);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "write control failed: %d", ret);
> +		return ret;
> +	}
> +
> +	xdma_chan->busy = true;
> +	return 0;
> +}
> +
> +static void xdma_channel_tasklet(struct tasklet_struct *t)
> +{
> +	struct xdma_chan *xdma_chan = from_tasklet(xdma_chan, t, tasklet);
> +
> +	spin_lock(&xdma_chan->vchan.lock);
> +	xdma_xfer_start(xdma_chan);
> +	spin_unlock(&xdma_chan->vchan.lock);
> +}
> +
> +/**
> + * xdma_config_channels - Detect and config DMA channels
> + * @xdev: DMA device pointer
> + * @dir: Channel direction
> + */
> +static int xdma_config_channels(struct xdma_device *xdev,
> +				enum dma_transfer_direction dir)
> +{
> +	struct xdma_platdata *pdata = dev_get_platdata(&xdev->pdev->dev);
> +	enum xdma_desc_field dev_addr_field, host_addr_field;
> +	u32 base, identifier, target;
> +	struct xdma_chan **chans;
> +	u32 *chan_num;
> +	int i, j, ret;
> +
> +	if (dir == DMA_MEM_TO_DEV) {
> +		base = XDMA_CHAN_H2C_OFFSET;
> +		target = XDMA_CHAN_H2C_TARGET;
> +		chans = &xdev->h2c_chans;
> +		chan_num = &xdev->h2c_chan_num;
> +		dev_addr_field = XDMA_DF_DST_ADDR_LO;
> +		host_addr_field = XDMA_DF_SRC_ADDR_LO;
> +	} else if (dir == DMA_DEV_TO_MEM) {
> +		base = XDMA_CHAN_C2H_OFFSET;
> +		target = XDMA_CHAN_C2H_TARGET;
> +		chans = &xdev->c2h_chans;
> +		chan_num = &xdev->c2h_chan_num;
> +		dev_addr_field = XDMA_DF_SRC_ADDR_LO;
> +		host_addr_field =  XDMA_DF_DST_ADDR_LO;
> +	} else {
> +		dev_err(&xdev->pdev->dev, "invalid direction specified");
> +		return -EINVAL;
> +	}
> +
> +	/* detect number of available DMA channels */
> +	for (i = 0, *chan_num = 0; i < pdata->max_dma_channels; i++) {
> +		ret = xdma_read_reg(xdev, base + i * XDMA_CHAN_STRIDE,
> +				    XDMA_CHAN_IDENTIFIER, &identifier);
> +		if (ret) {
> +			dev_err(&xdev->pdev->dev,
> +				"failed to read channel id: %d", ret);
> +			return ret;
> +		}
> +
> +		/* check if it is available DMA channel */
> +		if (XDMA_CHAN_CHECK_TARGET(identifier, target))
> +			(*chan_num)++;
> +	}
> +
> +	if (!*chan_num) {
> +		dev_err(&xdev->pdev->dev, "does not probe any channel");
> +		return -EINVAL;
> +	}
> +
> +	*chans = devm_kzalloc(&xdev->pdev->dev, sizeof(**chans) * (*chan_num),
> +			      GFP_KERNEL);
> +	if (!*chans)
> +		return -ENOMEM;
> +
> +	for (i = 0, j = 0; i < pdata->max_dma_channels; i++) {
> +		ret = xdma_read_reg(xdev, base + i * XDMA_CHAN_STRIDE,
> +				    XDMA_CHAN_IDENTIFIER, &identifier);
> +		if (ret) {
> +			dev_err(&xdev->pdev->dev,
> +				"failed to read channel id: %d", ret);
> +			return ret;
> +		}
> +
> +		if (!XDMA_CHAN_CHECK_TARGET(identifier, target))
> +			continue;
> +
> +		if (j == *chan_num) {
> +			dev_err(&xdev->pdev->dev, "invalid channel number");
> +			return -EIO;
> +		}
> +
> +		/* init channel structure and hardware */
> +		(*chans)[j].xdev_hdl = xdev;
> +		(*chans)[j].base = base + i * XDMA_CHAN_STRIDE;
> +		(*chans)[j].dir = dir;
> +		(*chans)[j].dev_addr_field = dev_addr_field;
> +		(*chans)[j].host_addr_field = host_addr_field;
> +
> +		ret = xdma_channel_init(&(*chans)[j]);
> +		if (ret)
> +			return ret;
> +		(*chans)[j].vchan.desc_free = xdma_free_tx_desc;
> +		vchan_init(&(*chans)[j].vchan, &xdev->dma_dev);
> +
> +		j++;
> +	}
> +
> +	dev_info(&xdev->pdev->dev, "configured %d %s channels", j,
> +		 (dir == DMA_MEM_TO_DEV) ? "H2C" : "C2H");
> +
> +	return 0;
> +}
> +
> +/**
> + * xdma_issue_pending - Issue pending transactions
> + * @chan: DMA channel pointer
> + */
> +static void xdma_issue_pending(struct dma_chan *chan)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&xdma_chan->vchan.lock, flags);
> +	if (vchan_issue_pending(&xdma_chan->vchan))
> +		xdma_xfer_start(xdma_chan);
> +	spin_unlock_irqrestore(&xdma_chan->vchan.lock, flags);
> +}
> +
> +/**
> + * xdma_prep_device_sg - prepare a descriptor for a
> + *	DMA transaction
> + * @chan: DMA channel pointer
> + * @sgl: Transfer scatter gather list
> + * @sg_len: Length of scatter gather list
> + * @dir: Transfer direction
> + * @flags: transfer ack flags
> + * @context: APP words of the descriptor
> + */
> +static struct dma_async_tx_descriptor *
> +xdma_prep_device_sg(struct dma_chan *chan, struct scatterlist *sgl,
> +		    unsigned int sg_len, enum dma_transfer_direction dir,
> +		    unsigned long flags, void *context)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct xdma_request *req;
> +
> +	req = kzalloc(sizeof(*req), GFP_NOWAIT);
> +	if (!req)
> +		return NULL;
> +
> +	req->sgl = sgl;
> +	req->dir = dir;
> +	req->nents = sg_len;
> +	if (dir == DMA_MEM_TO_DEV)
> +		req->dev_addr = xdma_chan->cfg.dst_addr;
> +	else
> +		req->dev_addr = xdma_chan->cfg.src_addr;
> +
> +	return vchan_tx_prep(&xdma_chan->vchan, &req->vdesc, flags);
> +}
> +
> +/**
> + * xdma_device_config - Configure the DMA channel
> + * @chan: DMA channel
> + * @cfg: channel configuration
> + */
> +static int xdma_device_config(struct dma_chan *chan,
> +			      struct dma_slave_config *cfg)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +
> +	memcpy(&xdma_chan->cfg, cfg, sizeof(*cfg));
> +
> +	return 0;
> +}
> +
> +/**
> + * xdma_free_chan_resources - Free channel resources
> + * @chan: DMA channel
> + */
> +static void xdma_free_chan_resources(struct dma_chan *chan)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct xdma_device *xdev = xdma_chan->xdev_hdl;
> +
> +	dma_free_coherent(&xdev->pdev->dev,
> +			  XDMA_DESC_BLOCK_NUM * XDMA_DESC_BLOCK_SIZE,
> +			  xdma_chan->desc_blocks[0].virt_addr,
> +			  xdma_chan->desc_blocks[0].dma_addr);
> +}
> +
> +/**
> + * xdma_alloc_chan_resources - Allocate channel resources
> + * @chan: DMA channel
> + */
> +static int xdma_alloc_chan_resources(struct dma_chan *chan)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct xdma_device *xdev = xdma_chan->xdev_hdl;
> +	dma_addr_t dma_addr;
> +	void *desc;
> +	int i;
> +
> +	desc = dma_alloc_coherent(&xdev->pdev->dev,
> +				  XDMA_DESC_BLOCK_NUM * XDMA_DESC_BLOCK_SIZE,
> +				  &dma_addr, GFP_KERNEL);
> +	if (!desc)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < XDMA_DESC_BLOCK_NUM; i++) {
> +		xdma_chan->desc_blocks[i].virt_addr = desc;
> +		xdma_chan->desc_blocks[i].dma_addr = dma_addr;
> +		desc += XDMA_DESC_BLOCK_SIZE;
> +		dma_addr += XDMA_DESC_BLOCK_SIZE;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * xdma_channel_isr - XDMA channel interrupt handler
> + * @irq: IRQ number
> + * @dev_id: Pointer to the DMA channel structure
> + */
> +static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
> +{
> +	struct xdma_chan *xdma_chan = dev_id;
> +	struct virt_dma_desc *vd;
> +	struct xdma_request *req;
> +
> +	spin_lock(&xdma_chan->vchan.lock);
> +
> +	/* get submitted request */
> +	vd = vchan_next_desc(&xdma_chan->vchan);
> +	if (!vd)
> +		goto out;
> +
> +	xdma_chan->busy = false;
> +	req = to_xdma_req(vd);
> +
> +	/*
> +	 * if all data blocks are transferred, remove and complete the
> +	 * request
> +	 */
> +	if (!req->sgl) {
> +		list_del(&vd->node);
> +		vchan_cookie_complete(vd);
> +	} else {
> +		/* transfer the rest of data */
> +		tasklet_schedule(&xdma_chan->tasklet);
> +	}
> +
> +out:
> +	spin_unlock(&xdma_chan->vchan.lock);
> +	return IRQ_HANDLED;
> +}
> +
> +/**
> + * xdma_irq_fini - Uninitialize IRQ
> + * @xdev: DMA device pointer
> + */
> +static void xdma_irq_fini(struct xdma_device *xdev)
> +{
> +	int ret, i;
> +
> +	/* disable interrupt */
> +	ret = xdma_disable_intr(xdev);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "failed to disable interrupts: %d",
> +			ret);
> +	}
> +
> +	/* free irq handler */
> +	for (i = 0; i < xdev->h2c_chan_num; i++) {
> +		free_irq(xdev->h2c_chans[i].irq, &xdev->h2c_chans[i]);
> +		tasklet_kill(&xdev->h2c_chans[i].tasklet);
> +	}
> +	for (i = 0; i < xdev->c2h_chan_num; i++) {
> +		free_irq(xdev->c2h_chans[i].irq, &xdev->c2h_chans[i]);
> +		tasklet_kill(&xdev->c2h_chans[i].tasklet);
> +	}
> +}
> +
> +/**
> + * xdma_set_vector_reg - configure hardware IRQ registers
> + * @xdev: DMA device pointer
> + * @vec_tbl_start: Start of IRQ registers
> + * @irq_start: Start of IRQ
> + * @irq_num: Number of IRQ
> + */
> +static int xdma_set_vector_reg(struct xdma_device *xdev, u32 vec_tbl_start,
> +			       u32 irq_start, u32 irq_num)
> +{
> +	u32 shift, i, val = 0;
> +	int ret;
> +
> +	/* Each IRQ register is 32 bit and contains 4 IRQs */
> +	while (irq_num > 0) {
> +		for (i = 0; i < 4; i++) {
> +			shift = XDMA_IRQ_VEC_SHIFT * i;
> +			val |= irq_start << shift;
> +			irq_start++;
> +			irq_num--;
> +		}
> +
> +		/* write IRQ register */
> +		ret = xdma_write_reg(xdev, XDMA_IRQ_BASE, vec_tbl_start, val);
> +		if (ret) {
> +			dev_err(&xdev->pdev->dev, "failed to set vector: %d",
> +				ret);
> +			return ret;
> +		}
> +		vec_tbl_start += sizeof(u32);
> +		val = 0;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * xdma_irq_init - initialize IRQs
> + * @xdev: DMA device pointer
> + */
> +static int xdma_irq_init(struct xdma_device *xdev)
> +{
> +	u32 irq = xdev->irq_start;
> +	int i, j, ret;
> +
> +	/* return failure if there are not enough IRQs */
> +	if (xdev->irq_num < xdev->h2c_chan_num + xdev->c2h_chan_num) {
> +		dev_err(&xdev->pdev->dev, "not enough irq");
> +		return -EINVAL;
> +	}
> +
> +	/* setup H2C interrupt handler */
> +	for (i = 0; i < xdev->h2c_chan_num; i++) {
> +		ret = request_irq(irq, xdma_channel_isr, 0,
> +				  "xdma-h2c-channel", &xdev->h2c_chans[i]);
> +		if (ret) {
> +			dev_err(&xdev->pdev->dev,
> +				"H2C channel%d request irq%d failed: %d",
> +				i, irq, ret);
> +			for (j = 0; j < i; j++) {
> +				free_irq(xdev->h2c_chans[j].irq,
> +					 &xdev->h2c_chans[j]);
> +			}
> +			return ret;
> +		}
> +		xdev->h2c_chans[i].irq = irq;
> +		tasklet_setup(&xdev->h2c_chans[i].tasklet,
> +			      xdma_channel_tasklet);
> +		irq++;
> +	}
> +
> +	/* setup C2H interrupt handler */
> +	for (i = 0; i < xdev->c2h_chan_num; i++) {
> +		ret = request_irq(irq, xdma_channel_isr, 0,
> +				  "xdma-c2h-channel", &xdev->c2h_chans[i]);
> +		if (ret) {
> +			dev_err(&xdev->pdev->dev,
> +				"H2C channel%d request irq%d failed: %d",
> +				i, irq, ret);
> +			for (j = 0; j < i; j++) {
> +				free_irq(xdev->c2h_chans[j].irq,
> +					 &xdev->c2h_chans[j]);
> +			}
> +			goto failed_init_c2h;
> +		}
> +		xdev->c2h_chans[i].irq = irq;
> +		tasklet_setup(&xdev->c2h_chans[i].tasklet,
> +			      xdma_channel_tasklet);
> +		irq++;
> +	}
> +
> +	/* config hardware IRQ registers */
> +	ret = xdma_set_vector_reg(xdev, XDMA_IRQ_CHAN_VEC_NUM, 0,
> +				  xdev->h2c_chan_num + xdev->c2h_chan_num);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "failed to set channel vectors: %d",
> +			ret);
> +		goto failed;
> +	}
> +
> +	/* enable interrupt */
> +	ret = xdma_enable_intr(xdev);
> +	if (ret) {
> +		dev_err(&xdev->pdev->dev, "failed to enable interrupts: %d",
> +			ret);
> +		goto failed;
> +	}
> +
> +	return 0;
> +
> +failed:
> +	for (i = 0; i < xdev->c2h_chan_num; i++)
> +		free_irq(xdev->c2h_chans[i].irq, &xdev->c2h_chans[i]);
> +failed_init_c2h:
> +	for (i = 0; i < xdev->h2c_chan_num; i++)
> +		free_irq(xdev->h2c_chans[i].irq, &xdev->h2c_chans[i]);
> +
> +	return ret;
> +}
> +
> +static bool xdma_filter_fn(struct dma_chan *chan, void *param)
> +{
> +	struct xdma_chan *xdma_chan = to_xdma_chan(chan);
> +	struct xdma_chan_info *chan_info = param;
> +
> +	if (chan_info->dir != xdma_chan->dir)
> +		return false;
> +
> +	return true;
> +}
> +
> +/**
> + * xdma_remove - Driver remove function
> + * @pdev: Pointer to the platform_device structure
> + */
> +static int xdma_remove(struct platform_device *pdev)
> +{
> +	struct xdma_device *xdev = platform_get_drvdata(pdev);
> +
> +	if (xdev->status & XDMA_DEV_STATUS_INIT_MSIX)
> +		xdma_irq_fini(xdev);
> +
> +	if (xdev->status & XDMA_DEV_STATUS_REG_DMA)
> +		dma_async_device_unregister(&xdev->dma_dev);
> +
> +	return 0;
> +}
> +
> +/**
> + * xdma_probe - Driver probe function
> + * @pdev: Pointer to the platform_device structure
> + */
> +static int xdma_probe(struct platform_device *pdev)
> +{
> +	struct xdma_platdata *pdata = dev_get_platdata(&pdev->dev);
> +	struct xdma_device *xdev;
> +	void __iomem *reg_base;
> +	struct resource *res;
> +	int ret = -ENODEV;
> +
> +	if (pdata->max_dma_channels > XDMA_MAX_CHANNELS) {
> +		dev_err(&pdev->dev, "invalid max dma channels %d",
> +			pdata->max_dma_channels);
> +		return -EINVAL;
> +	}
> +
> +	xdev = devm_kzalloc(&pdev->dev, sizeof(*xdev), GFP_KERNEL);
> +	if (!xdev)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, xdev);
> +	xdev->pdev = pdev;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> +	if (!res) {
> +		dev_err(&pdev->dev, "failed to get irq resource");
> +		goto failed;
> +	}
> +	xdev->irq_start = res->start;
> +	xdev->irq_num = res->end - res->start + 1;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(&pdev->dev, "failed to get io resource");
> +		goto failed;
> +	}
> +
> +	reg_base = devm_ioremap_resource(&pdev->dev, res);
> +	if (!reg_base) {
> +		dev_err(&pdev->dev, "ioremap failed");
> +		goto failed;
> +	}
> +
> +	xdev->regmap = devm_regmap_init_mmio(&pdev->dev, reg_base,
> +					     &xdma_regmap_config);
> +	if (!xdev->regmap) {
> +		dev_err(&pdev->dev, "config regmap failed: %d", ret);
> +		goto failed;
> +	}
> +	INIT_LIST_HEAD(&xdev->dma_dev.channels);
> +
> +	ret = xdma_config_channels(xdev, DMA_MEM_TO_DEV);
> +	if (ret) {
> +		dev_err(&pdev->dev, "config H2C channels failed: %d", ret);
> +		goto failed;
> +	}
> +
> +	ret = xdma_config_channels(xdev, DMA_DEV_TO_MEM);
> +	if (ret) {
> +		dev_err(&pdev->dev, "config C2H channels failed: %d", ret);
> +		goto failed;
> +	}
> +
> +	dma_cap_set(DMA_SLAVE, xdev->dma_dev.cap_mask);
> +	dma_cap_set(DMA_PRIVATE, xdev->dma_dev.cap_mask);
> +
> +	xdev->dma_dev.dev = &pdev->dev;
> +	xdev->dma_dev.device_free_chan_resources = xdma_free_chan_resources;
> +	xdev->dma_dev.device_alloc_chan_resources = xdma_alloc_chan_resources;
> +	xdev->dma_dev.device_tx_status = dma_cookie_status;
> +	xdev->dma_dev.device_prep_slave_sg = xdma_prep_device_sg;
> +	xdev->dma_dev.device_config = xdma_device_config;
> +	xdev->dma_dev.device_issue_pending = xdma_issue_pending;
> +	xdev->dma_dev.filter.map = pdata->device_map;
> +	xdev->dma_dev.filter.mapcnt = pdata->device_map_cnt;
> +	xdev->dma_dev.filter.fn = xdma_filter_fn;
> +
> +	ret = dma_async_device_register(&xdev->dma_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to register Xilinx XDMA: %d", ret);
> +		goto failed;
> +	}
> +	xdev->status |= XDMA_DEV_STATUS_REG_DMA;
> +
> +	ret = xdma_irq_init(xdev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to init msix: %d", ret);
> +		goto failed;
> +	}
> +	xdev->status |= XDMA_DEV_STATUS_INIT_MSIX;
> +
> +	return 0;
> +
> +failed:
> +	xdma_remove(pdev);
> +
> +	return ret;
> +}
> +
> +static const struct platform_device_id xdma_id_table[] = {
> +	{ "xdma", 0},
> +	{ },

Which entity creates this platform device?

> +};
> +
> +static struct platform_driver xdma_driver = {
> +	.driver		= {
> +		.name = "xdma",
> +	},
> +	.id_table	= xdma_id_table,
> +	.probe		= xdma_probe,
> +	.remove		= xdma_remove,
> +};
> +
> +module_platform_driver(xdma_driver);
> +
> +MODULE_DESCRIPTION("AMD XDMA driver");
> +MODULE_AUTHOR("XRT Team <runtime@xilinx.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/platform_data/amd_xdma.h b/include/linux/platform_data/amd_xdma.h
> new file mode 100644
> index 000000000000..04bcfc74ab36
> --- /dev/null
> +++ b/include/linux/platform_data/amd_xdma.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2022 Advanced Micro Devices, Inc. All rights reserved.
> + */
> +
> +#ifndef _PLATDATA_AMD_XDMA_H
> +#define _PLATDATA_AMD_XDMA_H
> +
> +#include <linux/dmaengine.h>
> +
> +/**
> + * struct xdma_chan_info - DMA channel information
> + *	This information is used to match channel when request dma channel
> + * @dir: Channel transfer direction
> + */
> +struct xdma_chan_info {
> +	enum dma_transfer_direction dir;
> +};
> +
> +#define XDMA_FILTER_PARAM(chan_info)	((void *)(chan_info))
> +
> +struct dma_slave_map;
> +
> +/**
> + * struct xdma_platdata - platform specific data for XDMA engine
> + * @max_dma_channels: Maximum dma channels in each direction
> + */
> +struct xdma_platdata {
> +	u32 max_dma_channels;
> +	u32 device_map_cnt;
> +	struct dma_slave_map *device_map;
> +};

who will set this platdata

-- 
~Vinod