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Date:   Fri, 4 Nov 2022 09:57:38 -0700
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Subject: Re: [PATCH V9 XDMA 1/2] dmaengine: xilinx: xdma: Add xilinx xdma
 driver
Content-Language: en-US
To:     Vinod Koul <vkoul@kernel.org>
CC:     <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <trix@redhat.com>, <tumic@gpxsee.org>, <max.zhen@amd.com>,
        <sonal.santan@amd.com>, <larry.liu@amd.com>, <brian.xu@amd.com>
References: <1666720638-33496-1-git-send-email-lizhi.hou@amd.com>
 <1666720638-33496-2-git-send-email-lizhi.hou@amd.com>
 <Y2Uidg/iuQdxwSaG@matsya>
From:   Lizhi Hou <lizhi.hou@amd.com>
In-Reply-To: <Y2Uidg/iuQdxwSaG@matsya>
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On 11/4/22 07:32, Vinod Koul wrote:
> On 25-10-22, 10:57, 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                    |  14 +
>>   drivers/dma/xilinx/Makefile            |   1 +
>>   drivers/dma/xilinx/xdma-regs.h         | 171 +++++
>>   drivers/dma/xilinx/xdma.c              | 954 +++++++++++++++++++++++++
>>   include/linux/platform_data/amd_xdma.h |  34 +
>>   6 files changed, 1184 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 e68a0804394d..d598c4e23901 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -22575,6 +22575,16 @@ 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/amd_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 7524b62a8870..bb5b542c2f9a 100644
>> --- a/drivers/dma/Kconfig
>> +++ b/drivers/dma/Kconfig
>> @@ -753,6 +753,20 @@ 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"
>> +	depends on HAS_IOMEM
>> +	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..bb8b38669d8d
>> --- /dev/null
>> +++ b/drivers/dma/xilinx/xdma-regs.h
>> @@ -0,0 +1,171 @@
>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>> +/*
>> + * Copyright (C) 2017-2020 Xilinx, Inc. All rights reserved.
>> + * Copyright (C) 2022, Advanced Micro Devices, Inc.
>> + */
>> +
>> +#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_HI_ADDR_MASK	GENMASK_ULL(63, 32)
>> +#define XDMA_LO_ADDR_MASK	GENMASK_ULL(31, 0)
>> +
>> +/*
>> + * 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		32
>> +#define XDMA_DESC_ADJACENT_MASK		(XDMA_DESC_ADJACENT - 1)
>> +#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))
> We have macros do that, please drop the xxx_SHIFT defines and use
> FIELD_GET/PREP to extract/set bits
Ok, I will use the macros.
>
>> +#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.
>> + */
>> +struct xdma_hw_desc {
>> +	__le32		control;
>> +	__le32		bytes;
>> +	__le64		src_addr;
>> +	__le64		dst_addr;
>> +	__le64		next_desc;
>> +};
>> +
>> +#define XDMA_DESC_SIZE		sizeof(struct xdma_hw_desc)
>> +#define XDMA_DESC_BLOCK_SIZE	(XDMA_DESC_SIZE * XDMA_DESC_ADJACENT)
>> +#define XDMA_DESC_BLOCK_ALIGN	4096
>> +
>> +/*
>> + * 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			GENMASK(13, 9)
>> +#define CHAN_CTRL_IE_DESC_ERROR			GENMASK(23, 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			GENMASK(13, 9)
>> +#define XDMA_CTRL_IE_DESC_ERROR			GENMASK(23, 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..85ba306c457e
>> --- /dev/null
>> +++ b/drivers/dma/xilinx/xdma.c
>> @@ -0,0 +1,954 @@
>> +// 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.
>> + */
>> +
>> +/*
>> + * 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/bitfield.h>
>> +#include <linux/dmapool.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 <linux/pci.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
>> + */
>> +struct xdma_desc_block {
>> +	void		*virt_addr;
>> +	dma_addr_t	dma_addr;
>> +};
>> +
>> +/**
>> + * struct xdma_chan - Driver specific DMA channel structure
>> + * @vchan: Virtual channel
>> + * @xdev_hdl: Pointer to DMA device structure
>> + * @base: Offset of channel registers
>> + * @desc_pool: Descriptor pool
>> + * @busy: Busy flag of the channel
>> + * @dir: Transferring direction of the channel
>> + * @cfg: Transferring config of the channel
>> + * @irq: IRQ assigned to the channel
>> + */
>> +struct xdma_chan {
>> +	struct virt_dma_chan		vchan;
>> +	void				*xdev_hdl;
>> +	u32				base;
>> +	struct dma_pool			*desc_pool;
>> +	bool				busy;
>> +	enum dma_transfer_direction	dir;
>> +	struct dma_slave_config		cfg;
>> +	u32				irq;
>> +};
>> +
>> +/**
>> + * struct xdma_desc - DMA desc structure
>> + * @vdesc: Virtual DMA descriptor
>> + * @chan: DMA channel pointer
>> + * @dir: Transferring direction of the request
>> + * @dev_addr: Physical address on DMA device side
>> + * @desc_blocks: Hardware descriptor blocks
>> + * @dblk_num: Number of hardware descriptor blocks
>> + * @desc_num: Number of hardware descriptors
>> + * @completed_desc_num: Completed hardware descriptors
>> + */
>> +struct xdma_desc {
>> +	struct virt_dma_desc		vdesc;
>> +	struct xdma_chan		*chan;
>> +	enum dma_transfer_direction	dir;
>> +	u64				dev_addr;
>> +	struct xdma_desc_block		*desc_blocks;
>> +	u32				dblk_num;
>> +	u32				desc_num;
>> +	u32				completed_desc_num;
>> +};
>> +
>> +#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;
>> +};
>> +
>> +#define xdma_err(xdev, fmt, args...)					\
>> +	dev_err(&(xdev)->pdev->dev, fmt, ##args)
>> +#define XDMA_CHAN_NUM(_xd) ({						\
>> +	typeof(_xd) (xd) = (_xd);					\
>> +	((xd)->h2c_chan_num + (xd)->c2h_chan_num); })
>> +
>> +/* Read and Write DMA registers */
>> +static inline int xdma_read_reg(struct xdma_device *xdev, u32 base, u32 reg,
>> +				u32 *val)
>> +{
>> +	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);
>> +}
> Do you really need one more level indirection?
Do you mean using readl / writel instead of regmap_* here?
>
>> +
>> +/* Get the last desc in a desc block */
>> +static inline void *xdma_blk_last_desc(struct xdma_desc_block *block)
>> +{
>> +	return block->virt_addr + (XDMA_DESC_ADJACENT - 1) * XDMA_DESC_SIZE;
>> +}
>> +
>> +/**
>> + * xdma_link_desc_blocks - Link descriptor blocks for DMA transfer
>> + * @sw_desc: Tx descriptor pointer
>> + */
>> +static void xdma_link_desc_blocks(struct xdma_desc *sw_desc)
>> +{
>> +	struct xdma_desc_block *block;
>> +	u32 last_blk_desc_num, desc_control;
>> +	struct xdma_hw_desc *desc;
>> +	int i;
>> +
>> +	desc_control = XDMA_DESC_CONTROL(XDMA_DESC_ADJACENT, 0);
>> +	for (i = 1; i < sw_desc->dblk_num; i++) {
>> +		block = &sw_desc->desc_blocks[i - 1];
>> +		desc = xdma_blk_last_desc(block);
>> +
>> +		if (!(i & XDMA_DESC_BLOCK_MASK)) {
>> +			desc->control = cpu_to_le32(XDMA_DESC_CONTROL_LAST);
>> +			continue;
>> +		}
>> +		desc->control = cpu_to_le32(desc_control);
>> +		desc->next_desc = cpu_to_le64(block[1].dma_addr);
>> +	}
>> +
>> +	/* update the last block */
>> +	last_blk_desc_num =
>> +		((sw_desc->desc_num - 1) & XDMA_DESC_ADJACENT_MASK) + 1;
> single line should do here, can you drop the outer brace
Ok.
>
>
>> +	if (((sw_desc->dblk_num - 1) & XDMA_DESC_BLOCK_MASK) > 0) {
>> +		block = &sw_desc->desc_blocks[sw_desc->dblk_num - 2];
>> +		desc = xdma_blk_last_desc(block);
>> +		desc_control = XDMA_DESC_CONTROL(last_blk_desc_num, 0);
>> +		desc->control = cpu_to_le32(desc_control);
>> +	}
>> +
>> +	block = &sw_desc->desc_blocks[sw_desc->dblk_num - 1];
>> +	desc = block->virt_addr + (last_blk_desc_num - 1) * XDMA_DESC_SIZE;
>> +	desc->control = cpu_to_le32(XDMA_DESC_CONTROL_LAST);
>> +}
>> +
>> +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_desc *to_xdma_desc(struct virt_dma_desc *vdesc)
>> +{
>> +	return container_of(vdesc, struct xdma_desc, 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)
>> +		xdma_err(xdev, "enable channel intr failed: %d", ret);
> why not move err into xdma_write_reg(), rather than adding in each
> helper!
Ok.
>
>
>> +
>> +	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)
>> +		xdma_err(xdev, "disable channel intr failed: %d", ret);
>> +
>> +	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) {
>> +		xdma_err(xdev, "clear non incr addr failed: %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = xdma_write_reg(xdev, chan->base, XDMA_CHAN_INTR_ENABLE,
>> +			     CHAN_IM_ALL);
>> +	if (ret) {
>> +		xdma_err(xdev, "failed to set interrupt mask: %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * xdma_free_desc - Free descriptor
>> + * @vdesc: Virtual DMA descriptor
>> + */
>> +static void xdma_free_desc(struct virt_dma_desc *vdesc)
>> +{
>> +	struct xdma_desc *sw_desc;
>> +	int i;
>> +
>> +	sw_desc = to_xdma_desc(vdesc);
>> +	for (i = 0; i < sw_desc->dblk_num; i++) {
>> +		if (!sw_desc->desc_blocks[i].virt_addr)
>> +			break;
>> +		dma_pool_free(sw_desc->chan->desc_pool,
>> +			      sw_desc->desc_blocks[i].virt_addr,
>> +			      sw_desc->desc_blocks[i].dma_addr);
>> +	}
>> +	kfree(sw_desc->desc_blocks);
>> +	kfree(sw_desc);
>> +}
>> +
>> +/**
>> + * xdma_alloc_desc - Allocate descriptor
>> + * @chan: DMA channel pointer
>> + * @desc_num: Number of hardware descriptors
>> + */
>> +static struct xdma_desc *
>> +xdma_alloc_desc(struct xdma_chan *chan, u32 desc_num)
>> +{
>> +	struct xdma_desc *sw_desc;
>> +	struct xdma_hw_desc *desc;
>> +	dma_addr_t dma_addr;
>> +	u32 dblk_num;
>> +	void *addr;
>> +	int i, j;
>> +
>> +	sw_desc = kzalloc(sizeof(*sw_desc), GFP_NOWAIT);
>> +	if (!sw_desc)
>> +		return NULL;
>> +
>> +	sw_desc->chan = chan;
>> +	sw_desc->desc_num = desc_num;
>> +	dblk_num = DIV_ROUND_UP(desc_num, XDMA_DESC_ADJACENT);
>> +	sw_desc->desc_blocks = kcalloc(dblk_num, sizeof(*sw_desc->desc_blocks),
>> +				       GFP_NOWAIT);
>> +	if (!sw_desc->desc_blocks)
>> +		goto failed;
>> +
>> +	sw_desc->dblk_num = dblk_num;
>> +	for (i = 0; i < sw_desc->dblk_num; i++) {
>> +		addr = dma_pool_alloc(chan->desc_pool, GFP_NOWAIT, &dma_addr);
>> +		if (!addr)
>> +			goto failed;
>> +
>> +		sw_desc->desc_blocks[i].virt_addr = addr;
>> +		sw_desc->desc_blocks[i].dma_addr = dma_addr;
>> +		for (j = 0, desc = addr; j < XDMA_DESC_ADJACENT; j++)
>> +			desc[j].control = cpu_to_le32(XDMA_DESC_CONTROL(1, 0));
>> +	}
>> +
>> +	xdma_link_desc_blocks(sw_desc);
>> +
>> +	return sw_desc;
>> +
>> +failed:
>> +	xdma_free_desc(&sw_desc->vdesc);
> who will free sw_desc here?
sw_desc is freed by xdma_free_desc(). xdma_free_desc() is virt-dma 
callback it converts struct virt_dma_desc pointer to driver sw_desc 
pointer and free the whole thing.
>
>> +	return NULL;
>> +}
>> +
>> +/**
>> + * 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;
>> +	struct xdma_desc_block *block;
>> +	u32 val, completed_blocks;
>> +	struct xdma_desc *desc;
>> +	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) {
>> +		xdma_err(xdev, "write control failed: %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	desc = to_xdma_desc(vd);
>> +	if (desc->dir != xdma_chan->dir) {
>> +		xdma_err(xdev, "incorrect request direction");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* set DMA engine to the first descriptor block */
>> +	completed_blocks = desc->completed_desc_num / XDMA_DESC_ADJACENT;
>> +	block = &desc->desc_blocks[completed_blocks];
>> +	val = FIELD_GET(XDMA_LO_ADDR_MASK, block->dma_addr);
>> +	ret = xdma_write_reg(xdev, XDMA_SGDMA_BASE(xdma_chan->base),
>> +			     XDMA_SGDMA_DESC_LO, val);
>> +	if (ret) {
>> +		xdma_err(xdev, "write hi addr failed: %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	val = FIELD_GET(XDMA_HI_ADDR_MASK, (u64)block->dma_addr);
>> +	ret = xdma_write_reg(xdev, XDMA_SGDMA_BASE(xdma_chan->base),
>> +			     XDMA_SGDMA_DESC_HI, val);
>> +	if (ret) {
>> +		xdma_err(xdev, "write lo addr failed: %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	if (completed_blocks + 1 == desc->dblk_num)
>> +		val = (desc->desc_num - 1) & XDMA_DESC_ADJACENT_MASK;
>> +	else
>> +		val = XDMA_DESC_ADJACENT - 1;
>> +	ret = xdma_write_reg(xdev, XDMA_SGDMA_BASE(xdma_chan->base),
>> +			     XDMA_SGDMA_DESC_ADJ, val);
>> +	if (ret) {
>> +		xdma_err(xdev, "write adjacent failed: %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* kick off DMA transfer */
>> +	ret = xdma_write_reg(xdev, xdma_chan->base, XDMA_CHAN_CONTROL,
>> +			     CHAN_CTRL_START);
>> +	if (ret) {
>> +		xdma_err(xdev, "write control failed: %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	xdma_chan->busy = true;
>> +	return 0;
>> +}
>> +
>> +/**
>> + * 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)
> pls align to preceeding line open brace... checkpatch --strict would
> warn you about style inconsistencies

This is due to "+ " added in front. The code is aligned after applying 
the patch.

checkpatch -strict is passed before I submitted my patches.

>
>> +{
>> +	struct xdma_platdata *pdata = dev_get_platdata(&xdev->pdev->dev);
>> +	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;
>> +	} 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;
>> +	} else {
>> +		xdma_err(xdev, "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) {
>> +			xdma_err(xdev, "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) {
>> +		xdma_err(xdev, "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) {
>> +			xdma_err(xdev, "failed to read channel id: %d", ret);
>> +			return ret;
>> +		}
>> +
>> +		if (!XDMA_CHAN_CHECK_TARGET(identifier, target))
>> +			continue;
>> +
>> +		if (j == *chan_num) {
>> +			xdma_err(xdev, "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;
>> +
>> +		ret = xdma_channel_init(&(*chans)[j]);
>> +		if (ret)
>> +			return ret;
>> +		(*chans)[j].vchan.desc_free = xdma_free_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 dma_async_tx_descriptor *tx_desc;
>> +	u32 desc_num = 0, i, len, rest;
>> +	struct xdma_desc_block *dblk;
>> +	struct xdma_hw_desc *desc;
>> +	struct xdma_desc *sw_desc;
>> +	u64 dev_addr, *src, *dst;
>> +	struct scatterlist *sg;
>> +	u64 addr;
>> +
>> +	for_each_sg(sgl, sg, sg_len, i)
>> +		desc_num += DIV_ROUND_UP(sg_dma_len(sg), XDMA_DESC_BLEN_MAX);
>> +
>> +	sw_desc = xdma_alloc_desc(xdma_chan, desc_num);
>> +	if (!sw_desc)
>> +		return NULL;
>> +	sw_desc->dir = dir;
>> +
>> +	if (dir == DMA_MEM_TO_DEV) {
>> +		dev_addr = xdma_chan->cfg.dst_addr;
>> +		src = &addr;
>> +		dst = &dev_addr;
>> +	} else {
>> +		dev_addr = xdma_chan->cfg.src_addr;
>> +		src = &dev_addr;
>> +		dst = &addr;
>> +	}
>> +
>> +	dblk = sw_desc->desc_blocks;
>> +	desc = dblk->virt_addr;
>> +	desc_num = 1;
>> +	for_each_sg(sgl, sg, sg_len, i) {
>> +		addr = sg_dma_address(sg);
>> +		rest = sg_dma_len(sg);
>> +
>> +		do {
>> +			len = min_t(u32, rest, XDMA_DESC_BLEN_MAX);
>> +			/* set hardware descriptor */
>> +			desc->bytes = cpu_to_le32(len);
>> +			desc->src_addr = cpu_to_le64(*src);
>> +			desc->dst_addr = cpu_to_le64(*dst);
>> +
>> +			if (!(desc_num & XDMA_DESC_ADJACENT_MASK)) {
>> +				dblk++;
>> +				desc = dblk->virt_addr;
>> +			} else {
>> +				desc++;
>> +			}
>> +
>> +			desc_num++;
>> +			dev_addr += len;
>> +			addr += len;
>> +			rest -= len;
>> +		} while (rest);
>> +	}
>> +
>> +	tx_desc = vchan_tx_prep(&xdma_chan->vchan, &sw_desc->vdesc, flags);
>> +	if (!tx_desc)
>> +		goto failed;
>> +
>> +	return tx_desc;
>> +
>> +failed:
>> +	xdma_free_desc(&sw_desc->vdesc);
>> +
>> +	return NULL;
>> +}
>> +
>> +/**
>> + * 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);
>> +
>> +	vchan_free_chan_resources(&xdma_chan->vchan);
>> +	dma_pool_destroy(xdma_chan->desc_pool);
>> +	xdma_chan->desc_pool = NULL;
>> +}
>> +
>> +/**
>> + * 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;
>> +	struct device *dev = xdev->dma_dev.dev;
>> +
>> +	while (dev && !dev_is_pci(dev))
>> +		dev = dev->parent;
>> +	if (!dev) {
>> +		xdma_err(xdev, "unable to find pci device");
>> +		return -EINVAL;
>> +	}
>> +
>> +	xdma_chan->desc_pool = dma_pool_create(dma_chan_name(chan),
>> +					       dev, XDMA_DESC_BLOCK_SIZE,
>> +					       XDMA_DESC_BLOCK_ALIGN, 0);
>> +	if (!xdma_chan->desc_pool) {
>> +		xdma_err(xdev, "unable to allocate descriptor pool");
>> +		return -ENOMEM;
>> +	}
>> +
>> +	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;
>> +	u32 complete_desc_num = 0;
>> +	struct virt_dma_desc *vd;
>> +	struct xdma_desc *desc;
>> +	int ret;
>> +
>> +	spin_lock(&xdma_chan->vchan.lock);
>> +
>> +	/* get submitted request */
>> +	vd = vchan_next_desc(&xdma_chan->vchan);
>> +	if (!vd)
>> +		goto out;
>> +
>> +	xdma_chan->busy = false;
>> +	desc = to_xdma_desc(vd);
>> +
>> +	ret = xdma_read_reg(xdma_chan->xdev_hdl, xdma_chan->base,
>> +			    XDMA_CHAN_COMPLETED_DESC, &complete_desc_num);
>> +	if (ret)
>> +		goto out;
>> +
>> +	desc->completed_desc_num += complete_desc_num;
>> +	/*
>> +	 * if all data blocks are transferred, remove and complete the request
>> +	 */
>> +	if (desc->completed_desc_num == desc->desc_num) {
>> +		list_del(&vd->node);
>> +		vchan_cookie_complete(vd);
>> +		goto out;
>> +	}
>> +
>> +	if (desc->completed_desc_num > desc->desc_num ||
>> +	    complete_desc_num != XDMA_DESC_BLOCK_NUM * XDMA_DESC_ADJACENT)
>> +		goto out;
>> +
>> +	/* transfer the rest of data */
>> +	xdma_xfer_start(xdma_chan);
>> +
>> +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)
>> +		xdma_err(xdev, "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]);
>> +
>> +	for (i = 0; i < xdev->c2h_chan_num; i++)
>> +		free_irq(xdev->c2h_chans[i].irq, &xdev->c2h_chans[i]);
>> +}
>> +
>> +/**
>> + * 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) {
>> +			xdma_err(xdev, "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 < XDMA_CHAN_NUM(xdev)) {
>> +		xdma_err(xdev, "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) {
>> +			xdma_err(xdev, "H2C channel%d request irq%d failed: %d",
>> +				 i, irq, ret);
>> +			goto failed_init_h2c;
>> +		}
>> +		xdev->h2c_chans[i].irq = irq;
>> +		irq++;
>> +	}
>> +
>> +	/* setup C2H interrupt handler */
>> +	for (j = 0; j < xdev->c2h_chan_num; j++) {
>> +		ret = request_irq(irq, xdma_channel_isr, 0,
>> +				  "xdma-c2h-channel", &xdev->c2h_chans[j]);
>> +		if (ret) {
>> +			xdma_err(xdev, "H2C channel%d request irq%d failed: %d",
>> +				 j, irq, ret);
>> +			goto failed_init_c2h;
>> +		}
>> +		xdev->c2h_chans[j].irq = irq;
>> +		irq++;
>> +	}
>> +
>> +	/* config hardware IRQ registers */
>> +	ret = xdma_set_vector_reg(xdev, XDMA_IRQ_CHAN_VEC_NUM, 0,
>> +				  XDMA_CHAN_NUM(xdev));
>> +	if (ret) {
>> +		xdma_err(xdev, "failed to set channel vectors: %d", ret);
>> +		goto failed_init_c2h;
>> +	}
>> +
>> +	/* enable interrupt */
>> +	ret = xdma_enable_intr(xdev);
>> +	if (ret) {
>> +		xdma_err(xdev, "failed to enable interrupts: %d", ret);
>> +		goto failed_init_c2h;
>> +	}
>> +
>> +	return 0;
>> +
>> +failed_init_c2h:
>> +	while (j--)
>> +		free_irq(xdev->c2h_chans[j].irq, &xdev->c2h_chans[j]);
>> +failed_init_h2c:
>> +	while (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;
>> +
>> +	return chan_info->dir == xdma_chan->dir;
>> +}
>> +
>> +/**
>> + * 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) {
>> +		xdma_err(xdev, "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) {
>> +		xdma_err(xdev, "failed to get io resource");
>> +		goto failed;
>> +	}
>> +
>> +	reg_base = devm_ioremap_resource(&pdev->dev, res);
>> +	if (!reg_base) {
>> +		xdma_err(xdev, "ioremap failed");
>> +		goto failed;
>> +	}
>> +
>> +	xdev->regmap = devm_regmap_init_mmio(&pdev->dev, reg_base,
>> +					     &xdma_regmap_config);
>> +	if (!xdev->regmap) {
>> +		xdma_err(xdev, "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) {
>> +		xdma_err(xdev, "config H2C channels failed: %d", ret);
>> +		goto failed;
>> +	}
>> +
>> +	ret = xdma_config_channels(xdev, DMA_DEV_TO_MEM);
>> +	if (ret) {
>> +		xdma_err(xdev, "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) {
>> +		xdma_err(xdev, "failed to register Xilinx XDMA: %d", ret);
>> +		goto failed;
>> +	}
>> +	xdev->status |= XDMA_DEV_STATUS_REG_DMA;
>> +
>> +	ret = xdma_irq_init(xdev);
>> +	if (ret) {
>> +		xdma_err(xdev, "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},
>> +	{ },
>> +};
>> +
>> +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 <runtimeca39d@amd.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..b5e23e14bac8
>> --- /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.
>> + */
>> +
>> +#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;
>> +};
> why do you need this plat data

max_dma_channels is used to specify the maximum dma channels will be used.

device_map and device_map_cnt are used to define the dma channel names 
which are used by dma_request_chan().

One of the existing example is: include/linux/platform_data/mmp_dma.h


Thanks,

Lizhi

>
>> +
>> +#endif /* _PLATDATA_AMD_XDMA_H */
>> -- 
>> 2.27.0