Re: [RESEND PATCH] dmaengine: Add Xilinx AXI Direct Memory Access Engine driver support

From: Moritz Fischer
Date: Thu Aug 20 2015 - 21:16:47 EST

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In reply to: Appana Durga Kedareswara Rao: "RE: [RESEND PATCH] dmaengine: Add Xilinx AXI Direct Memory Access Engine driver support"
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Hi,

your MUA produces funny messages somehow ...
The driver did not probe for me in it's current form as the bindings
were missing interrupt parents for the interrupts...

On Thu, Aug 20, 2015 at 12:01 AM, Appana Durga Kedareswara Rao
<appana.durga.rao@xxxxxxxxxx> wrote:
> Hi ,
>
>> -----Original Message-----
>> From: dmaengine-owner@xxxxxxxxxxxxxxx [mailto:dmaengine-
>> owner@xxxxxxxxxxxxxxx] On Behalf Of Appana Durga Kedareswara Rao
>> Sent: Thursday, August 20, 2015 11:11 AM
>> To: Moritz Fischer
>> Cc: vinod.koul@xxxxxxxxx; dan.j.williams@xxxxxxxxx; Michal Simek; Soren
>> Brinkmann; anirudha@xxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx; linux-
>> kernel@xxxxxxxxxxxxxxx; linux-arm-kernel
>> Subject: RE: [RESEND PATCH] dmaengine: Add Xilinx AXI Direct Memory Access
>> Engine driver support
>>
>> Hi Moritz Fischer,
>>
>> Thanks for reviewing the patch.
>>
>> > -----Original Message-----
>> > From: Moritz Fischer [mailto:moritz.fischer@xxxxxxxxx]
>> > Sent: Thursday, August 20, 2015 3:21 AM
>> > To: Appana Durga Kedareswara Rao
>> > Cc: vinod.koul@xxxxxxxxx; dan.j.williams@xxxxxxxxx; Michal Simek;
>> > Soren Brinkmann; Appana Durga Kedareswara Rao; anirudha@xxxxxxxxxx;
>> > dmaengine@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
>> > linux-arm-kernel; Srikanth Thokala
>> > Subject: Re: [RESEND PATCH] dmaengine: Add Xilinx AXI Direct Memory
>> > Access Engine driver support
>> >
>> > Hi there,
>> >
>> > see comment below. I just did a quick compile test. Will take another
>> > look once I synthesized an image.
>> >
>> > On Mon, Aug 17, 2015 at 8:31 AM, Kedareswara rao Appana
>> > <appana.durga.rao@xxxxxxxxxx> wrote:
>> > > This is the driver for the AXI Direct Memory Access (AXI DMA) core,
>> > > which is a soft Xilinx IP core that provides high- bandwidth direct
>> > > memory access between memory and AXI4-Stream type target peripherals.
>> > >
>> > > Signed-off-by: Srikanth Thokala <sthokal@xxxxxxxxxx>
>> > > Signed-off-by: Kedareswara rao Appana <appanad@xxxxxxxxxx>
>> > > ---
>> > > The deivce tree doc got applied in the slave-dmaengine.git.
>> > >
>> > > Forgot to include dmaengine@xxxxxxxxxxxxxxx in the cc list resending
>> > > the patch.
>> > >
>> > > Changes in v8:
>> > > - Updated the SG handling as suggested by Nicolae Rosia.
>> > > - Removed the unnecessary xilinx_dma_channel_set_config API the
>> properties
>> > > in this API is not being used by the driver.
>> > > Changes in v7:
>> > > - Updated license in the driver as suggested by Paul.
>> > > - Corrected return value in is_idle funtion.
>> > > Changes in v6:
>> > > - Fixed Odd indention in the Kconfig.
>> > > - used GFP_NOWAIT instead of GFP_KERNEL during the desc allocation
>> > > - Calculated residue in the tx_status instead of complete_descriptor.
>> > > - Update copy right to 2015.
>> > > - Modified spin_lock handling moved the spin_lock to the appropriate
>> > > functions (instead of xilinx_dma_start_transfer doing it
>> > xilinx_dma_issue_pending api).
>> > > - device_control and declare slave caps updated as per newer APi's.
>> > > Changes in v5:
>> > > - Modified the xilinx_dma.h header file location to the
>> > > include/linux/dma/xilinx_dma.h
>> > > Changes in v4:
>> > > - Add direction field to DMA descriptor structure and removed from
>> > > channel structure to avoid duplication.
>> > > - Check for DMA idle condition before changing the configuration.
>> > > - Residue is being calculated in complete_descriptor() and is reported
>> > > to slave driver.
>> > > Changes in v3:
>> > > - Rebased on 3.16-rc7
>> > > Changes in v2:
>> > > - Simplified the logic to set SOP and APP words in prep_slave_sg().
>> > > - Corrected function description comments to match the return type.
>> > > - Fixed some minor comments as suggested by Andy.
>> > >
>> > > drivers/dma/Kconfig | 13 +
>> > > drivers/dma/xilinx/Makefile | 1 +
>> > > drivers/dma/xilinx/xilinx_dma.c | 1179
>> > > +++++++++++++++++++++++++++++++++++++++
>> > > 3 files changed, 1193 insertions(+) create mode 100644
>> > > drivers/dma/xilinx/xilinx_dma.c
>> > >
>> > > diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig index
>> > > 88d474b..5e95f07 100644
>> > > --- a/drivers/dma/Kconfig
>> > > +++ b/drivers/dma/Kconfig
>> > > @@ -507,4 +507,17 @@ config QCOM_BAM_DMA
>> > > Enable support for the QCOM BAM DMA controller. This controller
>> > > provides DMA capabilities for a variety of on-chip devices.
>> > >
>> > > +config XILINX_DMA
>> > > + tristate "Xilinx AXI DMA Engine"
>> > > + depends on (ARCH_ZYNQ || MICROBLAZE)
>> > > + select DMA_ENGINE
>> > > + help
>> > > + Enable support for Xilinx AXI DMA Soft IP.
>> > > +
>> > > + This engine provides high-bandwidth direct memory access
>> > > + between memory and AXI4-Stream type target peripherals.
>> > > + It has two stream interfaces/channels, Memory Mapped to
>> > > + Stream (MM2S) and Stream to Memory Mapped (S2MM) for the
>> > > + data transfers.
>> > > +
>> > > endif
>> > > diff --git a/drivers/dma/xilinx/Makefile
>> > > b/drivers/dma/xilinx/Makefile index 3c4e9f2..6224a49 100644
>> > > --- a/drivers/dma/xilinx/Makefile
>> > > +++ b/drivers/dma/xilinx/Makefile
>> > > @@ -1 +1,2 @@
>> > > obj-$(CONFIG_XILINX_VDMA) += xilinx_vdma.o
>> > > +obj-$(CONFIG_XILINX_DMA) += xilinx_dma.o
>> > > diff --git a/drivers/dma/xilinx/xilinx_dma.c
>> > > b/drivers/dma/xilinx/xilinx_dma.c new file mode 100644 index
>> > > 0000000..a9be197
>> > > --- /dev/null
>> > > +++ b/drivers/dma/xilinx/xilinx_dma.c
>> > > @@ -0,0 +1,1179 @@
>> > > +/*
>> > > + * DMA driver for Xilinx DMA Engine
>> > > + *
>> > > + * Copyright (C) 2010 - 2015 Xilinx, Inc. All rights reserved.
>> > > + *
>> > > + * Based on the Freescale DMA driver.
>> > > + *
>> > > + * Description:
>> > > + * The AXI DMA, is a soft IP, which provides high-bandwidth Direct
>> > > +Memory
>> > > + * Access between memory and AXI4-Stream-type target peripherals.
>> > > +It can be
>> > > + * configured to have one channel or two channels and if
>> > > +configured as two
>> > > + * channels, one is to transmit data from memory to a device and
>> > > +another is
>> > > + * to receive from a device.
>> > > + *
>> > > + * This is free software; you can redistribute it and/or modify
>> > > + * it under the terms of the GNU General Public License as
>> > > +published by
>> > > + * the Free Software Foundation; either version 2 of the License,
>> > > +or
>> > > + * (at your option) any later version.
>> > > + */
>> > > +
>> > > +#include <linux/bitops.h>
>> > > +#include <linux/dma/xilinx_dma.h>
>> > > +#include <linux/init.h>
>> > > +#include <linux/interrupt.h>
>> > > +#include <linux/io.h>
>> > > +#include <linux/module.h>
>> > > +#include <linux/of_address.h>
>> > > +#include <linux/of_dma.h>
>> > > +#include <linux/of_irq.h>
>> > > +#include <linux/of_platform.h>
>> > > +#include <linux/slab.h>
>> > > +
>> > > +#include "../dmaengine.h"
>> > > +
>> > > +/* Register Offsets */
>> > > +#define XILINX_DMA_REG_CONTROL 0x00
>> > > +#define XILINX_DMA_REG_STATUS 0x04
>> > > +#define XILINX_DMA_REG_CURDESC 0x08
>> > > +#define XILINX_DMA_REG_TAILDESC 0x10
>> > > +#define XILINX_DMA_REG_SRCADDR 0x18
>> > > +#define XILINX_DMA_REG_DSTADDR 0x20
>> > > +#define XILINX_DMA_REG_BTT 0x28
>> > > +
>> > > +/* Channel/Descriptor Offsets */
>> > > +#define XILINX_DMA_MM2S_CTRL_OFFSET 0x00
>> > > +#define XILINX_DMA_S2MM_CTRL_OFFSET 0x30
>> > > +
>> > > +/* General register bits definitions */
>> > > +#define XILINX_DMA_CR_RUNSTOP_MASK BIT(0)
>> > > +#define XILINX_DMA_CR_RESET_MASK BIT(2)
>> > > +
>> > > +#define XILINX_DMA_CR_DELAY_SHIFT 24
>> > > +#define XILINX_DMA_CR_COALESCE_SHIFT 16
>> > > +
>> > > +#define XILINX_DMA_CR_DELAY_MAX GENMASK(7, 0)
>> > > +#define XILINX_DMA_CR_COALESCE_MAX GENMASK(7, 0)
>> > > +
>> > > +#define XILINX_DMA_SR_HALTED_MASK BIT(0)
>> > > +#define XILINX_DMA_SR_IDLE_MASK BIT(1)
>> > > +
>> > > +#define XILINX_DMA_XR_IRQ_IOC_MASK BIT(12)
>> > > +#define XILINX_DMA_XR_IRQ_DELAY_MASK BIT(13)
>> > > +#define XILINX_DMA_XR_IRQ_ERROR_MASK BIT(14)
>> > > +#define XILINX_DMA_XR_IRQ_ALL_MASK GENMASK(14, 12)
>> > > +
>> > > +/* BD definitions */
>> > > +#define XILINX_DMA_BD_STS_ALL_MASK GENMASK(31, 28)
>> > > +#define XILINX_DMA_BD_SOP BIT(27)
>> > > +#define XILINX_DMA_BD_EOP BIT(26)
>> > > +
>> > > +/* Hw specific definitions */
>> > > +#define XILINX_DMA_MAX_CHANS_PER_DEVICE 0x2
>> > > +#define XILINX_DMA_MAX_TRANS_LEN GENMASK(22, 0)
>> > > +
>> > > +/* Delay loop counter to prevent hardware failure */
>> > > +#define XILINX_DMA_LOOP_COUNT 1000000
>> > > +
>> > > +/* Maximum number of Descriptors */
>> > > +#define XILINX_DMA_NUM_DESCS 255
>> > > +#define XILINX_DMA_COALESCE_MAX 255
>> > > +#define XILINX_DMA_NUM_APP_WORDS 5
>> > > +
>> > > +/**
>> > > + * struct xilinx_dma_desc_hw - Hardware Descriptor
>> > > + * @next_desc: Next Descriptor Pointer @0x00
>> > > + * @pad1: Reserved @0x04
>> > > + * @buf_addr: Buffer address @0x08
>> > > + * @pad2: Reserved @0x0C
>> > > + * @pad3: Reserved @0x10
>> > > + * @pad4: Reserved @0x14
>> > > + * @control: Control field @0x18
>> > > + * @status: Status field @0x1C
>> > > + * @app: APP Fields @0x20 - 0x30
>> > > + */
>> > > +struct xilinx_dma_desc_hw {
>> > > + u32 next_desc;
>> > > + u32 pad1;
>> > > + u32 buf_addr;
>> > > + u32 pad2;
>> > > + u32 pad3;
>> > > + u32 pad4;
>> > > + u32 control;
>> > > + u32 status;
>> > > + u32 app[XILINX_DMA_NUM_APP_WORDS]; } __aligned(64);
>> > > +
>> > > +/**
>> > > + * struct xilinx_dma_tx_segment - Descriptor segment
>> > > + * @hw: Hardware descriptor
>> > > + * @node: Node in the descriptor segments list
>> > > + * @phys: Physical address of segment */ struct
>> > > +xilinx_dma_tx_segment {
>> > > + struct xilinx_dma_desc_hw hw;
>> > > + struct list_head node;
>> > > + dma_addr_t phys;
>> > > +} __aligned(64);
>> > > +
>> > > +/**
>> > > + * struct xilinx_dma_tx_descriptor - Per Transaction structure
>> > > + * @async_tx: Async transaction descriptor
>> > > + * @segments: TX segments list
>> > > + * @node: Node in the channel descriptors list
>> > > + * @direction: Transfer direction
>> > > + */
>> > > +struct xilinx_dma_tx_descriptor {
>> > > + struct dma_async_tx_descriptor async_tx;
>> > > + struct list_head segments;
>> > > + struct list_head node;
>> > > + enum dma_transfer_direction direction; };
>> > > +
>> > > +/**
>> > > + * struct xilinx_dma_chan - Driver specific DMA channel structure
>> > > + * @xdev: Driver specific device structure
>> > > + * @ctrl_offset: Control registers offset
>> > > + * @ctrl_reg: Control register value
>> > > + * @lock: Descriptor operation lock
>> > > + * @pending_list: Descriptors waiting
>> > > + * @active_list: Descriptors ready to submit
>> > > + * @done_list: Complete descriptors
>> > > + * @free_seg_list: Free descriptors
>> > > + * @common: DMA common channel
>> > > + * @seg_v: Statically allocated segments base
>> > > + * @seg_p: Physical allocated segments base
>> > > + * @dev: The dma device
>> > > + * @irq: Channel IRQ
>> > > + * @id: Channel ID
>> > > + * @has_sg: Support scatter transfers
>> > > + * @idle: Check for channel idle
>> > > + * @err: Channel has errors
>> > > + * @tasklet: Cleanup work after irq
>> > > + * @residue: Residue
>> > > + * @desc_pendingcount: Descriptor pending count */ struct
>> > > +xilinx_dma_chan {
>> > > + struct xilinx_dma_device *xdev;
>> > > + u32 ctrl_offset;
>> > > + u32 ctrl_reg;
>> > > + spinlock_t lock;
>> > > + struct list_head pending_list;
>> > > + struct list_head done_list;
>> > > + struct list_head active_list;
>> > > + struct list_head free_seg_list;
>> > > + struct dma_chan common;
>> > > + struct xilinx_dma_tx_segment *seg_v;
>> > > + dma_addr_t seg_p;
>> > > + struct device *dev;
>> > > + int irq;
>> > > + int id;
>> > > + bool has_sg;
>> > > + bool idle;
>> > > + int err;
>> > > + struct tasklet_struct tasklet;
>> > > + u32 residue;
>> > > + u32 desc_pendingcount;
>> > > +};
>> > > +
>> > > +/**
>> > > + * struct xilinx_dma_device - DMA device structure
>> > > + * @regs: I/O mapped base address
>> > > + * @dev: Device Structure
>> > > + * @common: DMA device structure
>> > > + * @chan: Driver specific DMA channel
>> > > + * @has_sg: Specifies whether Scatter-Gather is present or not */
>> > > +struct xilinx_dma_device {
>> > > + void __iomem *regs;
>> > > + struct device *dev;
>> > > + struct dma_device common;
>> > > + struct xilinx_dma_chan
>> *chan[XILINX_DMA_MAX_CHANS_PER_DEVICE];
>> > > + bool has_sg;
>> > > +};
>> > > +
>> > > +/* Macros */
>> > > +#define to_xilinx_chan(chan) \
>> > > + container_of(chan, struct xilinx_dma_chan, common) #define
>> > > +to_dma_tx_descriptor(tx) \
>> > > + container_of(tx, struct xilinx_dma_tx_descriptor, async_tx)
>> > > +
>> > > +/* IO accessors */
>> > > +static inline void dma_write(struct xilinx_dma_chan *chan, u32 reg,
>> > > +u32 value) {
>> > > + iowrite32(value, chan->xdev->regs + reg);
>> > Any reason to not use write here?
>> Most of the Xilinx drivers and the VDMA driver that got up streamed Use iowrite
>> to make consistency b/w the drivers I used the same API's.
>>
>> What is the advantage we will gain by using writel instead of iowrite32?

https://lkml.org/lkml/2011/1/19/158
>>
>> > > +}
>> > > +
>> > > +static inline u32 dma_read(struct xilinx_dma_chan *chan, u32 reg) {
>> > > + return ioread32(chan->xdev->regs + reg);
>> > Any reason to not use readl here?
>> > > +}
>> > > +
>> > > +static inline u32 dma_ctrl_read(struct xilinx_dma_chan *chan, u32
>> > > +reg) {
>> > > + return dma_read(chan, chan->ctrl_offset + reg); }
>> > > +
>> > > +static inline void dma_ctrl_write(struct xilinx_dma_chan *chan, u32 reg,
>> > > + u32 value) {
>> > > + dma_write(chan, chan->ctrl_offset + reg, value); }
>> > > +
>> > > +/*
>> > > +-------------------------------------------------------------------
>> > > +--
>> > > +--------
>> > > + * Descriptors and segments alloc and free */
>> > > +
>> > > +/**
>> > > + * xilinx_dma_alloc_tx_segment - Allocate transaction segment
>> > > + * @chan: Driver specific dma channel
>> > > + *
>> > > + * Return: The allocated segment on success and NULL on failure.
>> > > + */
>> > > +static struct xilinx_dma_tx_segment *
>> > > +xilinx_dma_alloc_tx_segment(struct xilinx_dma_chan *chan) {
>> > > + struct xilinx_dma_tx_segment *segment = NULL;
>> > > + unsigned long flags;
>> > > +
>> > > + spin_lock_irqsave(&chan->lock, flags);
>> > > + if (!list_empty(&chan->free_seg_list)) {
>> > > + segment = list_first_entry(&chan->free_seg_list,
>> > > + struct xilinx_dma_tx_segment,
>> > > + node);
>> > > + list_del(&segment->node);
>> > > + }
>> > > + spin_unlock_irqrestore(&chan->lock, flags);
>> > > +
>> > > + return segment;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_clean_hw_desc - Clean hardware descriptor
>> > > + * @hw: HW descriptor to clean
>> > > + */
>> > > +static void xilinx_dma_clean_hw_desc(struct xilinx_dma_desc_hw *hw) {
>> > > + u32 next_desc = hw->next_desc;
>> > > +
>> > > + memset(hw, 0, sizeof(struct xilinx_dma_desc_hw));
>> > > +
>> > > + hw->next_desc = next_desc;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_free_tx_segment - Free transaction segment
>> > > + * @chan: Driver specific dma channel
>> > > + * @segment: dma transaction segment */ static void
>> > > +xilinx_dma_free_tx_segment(struct xilinx_dma_chan *chan,
>> > > + struct xilinx_dma_tx_segment
>> > > +*segment) {
>> > > + xilinx_dma_clean_hw_desc(&segment->hw);
>> > > +
>> > > + list_add_tail(&segment->node, &chan->free_seg_list); }
>> > > +
>> > > +/**
>> > > + * xilinx_dma_tx_descriptor - Allocate transaction descriptor
>> > > + * @chan: Driver specific dma channel
>> > > + *
>> > > + * Return: The allocated descriptor on success and NULL on failure.
>> > > + */
>> > > +static struct xilinx_dma_tx_descriptor *
>> > > +xilinx_dma_alloc_tx_descriptor(struct xilinx_dma_chan *chan) {
>> > > + struct xilinx_dma_tx_descriptor *desc;
>> > > +
>> > > + desc = kzalloc(sizeof(*desc), GFP_NOWAIT);
>> > > + if (!desc)
>> > > + return NULL;
>> > > +
>> > > + INIT_LIST_HEAD(&desc->segments);
>> > > +
>> > > + return desc;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_free_tx_descriptor - Free transaction descriptor
>> > > + * @chan: Driver specific dma channel
>> > > + * @desc: dma transaction descriptor */ static void
>> > > +xilinx_dma_free_tx_descriptor(struct xilinx_dma_chan *chan,
>> > > + struct xilinx_dma_tx_descriptor *desc) {
>> > > + struct xilinx_dma_tx_segment *segment, *next;
>> > > +
>> > > + if (!desc)
>> > > + return;
>> > > +
>> > > + list_for_each_entry_safe(segment, next, &desc->segments, node) {
>> > > + list_del(&segment->node);
>> > > + xilinx_dma_free_tx_segment(chan, segment);
>> > > + }
>> > > +
>> > > + kfree(desc);
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_alloc_chan_resources - Allocate channel resources
>> > > + * @dchan: DMA channel
>> > > + *
>> > > + * Return: '0' on success and failure value on error */ static int
>> > > +xilinx_dma_alloc_chan_resources(struct dma_chan *dchan) {
>> > > + struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
>> > > + int i;
>> > > +
>> > > + /* Allocate the buffer descriptors. */
>> > > + chan->seg_v = dma_zalloc_coherent(chan->dev,
>> > > + sizeof(*chan->seg_v) *
>> > > + XILINX_DMA_NUM_DESCS,
>> > > + &chan->seg_p, GFP_KERNEL);
>> > > + if (!chan->seg_v) {
>> > > + dev_err(chan->dev,
>> > > + "unable to allocate channel %d descriptors\n",
>> > > + chan->id);
>> > > + return -ENOMEM;
>> > > + }
>> > > +
>> > > + for (i = 0; i < XILINX_DMA_NUM_DESCS; i++) {
>> > > + chan->seg_v[i].hw.next_desc =
>> > > + chan->seg_p + sizeof(*chan->seg_v) *
>> > > + ((i + 1) % XILINX_DMA_NUM_DESCS);
>> > > + chan->seg_v[i].phys =
>> > > + chan->seg_p + sizeof(*chan->seg_v) * i;
>> > > + list_add_tail(&chan->seg_v[i].node, &chan->free_seg_list);
>> > > + }
>> > > +
>> > > + dma_cookie_init(dchan);
>> > > +
>> > > + /* Enable interrupts */
>> > > + chan->ctrl_reg |= XILINX_DMA_XR_IRQ_ALL_MASK;
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_CONTROL,
>> > > + chan->ctrl_reg);
>> > > +
>> > > + return 0;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_free_desc_list - Free descriptors list
>> > > + * @chan: Driver specific dma channel
>> > > + * @list: List to parse and delete the descriptor */ static void
>> > > +xilinx_dma_free_desc_list(struct xilinx_dma_chan *chan,
>> > > + struct list_head *list) {
>> > > + struct xilinx_dma_tx_descriptor *desc, *next;
>> > > +
>> > > + list_for_each_entry_safe(desc, next, list, node) {
>> > > + list_del(&desc->node);
>> > > + xilinx_dma_free_tx_descriptor(chan, desc);
>> > > + }
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_free_descriptors - Free channel descriptors
>> > > + * @chan: Driver specific dma channel */ static void
>> > > +xilinx_dma_free_descriptors(struct xilinx_dma_chan *chan) {
>> > > + unsigned long flags;
>> > > +
>> > > + spin_lock_irqsave(&chan->lock, flags);
>> > > +
>> > > + xilinx_dma_free_desc_list(chan, &chan->pending_list);
>> > > + xilinx_dma_free_desc_list(chan, &chan->done_list);
>> > > + xilinx_dma_free_desc_list(chan, &chan->active_list);
>> > > +
>> > > + spin_unlock_irqrestore(&chan->lock, flags); }
>> > > +
>> > > +/**
>> > > + * xilinx_dma_free_chan_resources - Free channel resources
>> > > + * @dchan: DMA channel
>> > > + */
>> > > +static void xilinx_dma_free_chan_resources(struct dma_chan *dchan) {
>> > > + struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
>> > > +
>> > > + xilinx_dma_free_descriptors(chan);
>> > > +
>> > > + dma_free_coherent(chan->dev,
>> > > + sizeof(*chan->seg_v) * XILINX_DMA_NUM_DESCS,
>> > > + chan->seg_v, chan->seg_p); }
>> > > +
>> > > +/**
>> > > + * xilinx_dma_chan_desc_cleanup - Clean channel descriptors
>> > > + * @chan: Driver specific dma channel */ static void
>> > > +xilinx_dma_chan_desc_cleanup(struct xilinx_dma_chan *chan) {
>> > > + struct xilinx_dma_tx_descriptor *desc;
>> > > + unsigned long flags;
>> > > +
>> > > + spin_lock_irqsave(&chan->lock, flags);
>> > > +
>> > > + while (!list_empty(&chan->done_list)) {
>> > > + dma_async_tx_callback callback;
>> > > + void *callback_param;
>> > > +
>> > > + desc = list_first_entry(&chan->done_list,
>> > > + struct xilinx_dma_tx_descriptor, node);
>> > > +
>> > > + /* Remove from the list of running transactions */
>> > > + list_del(&desc->node);
>> > > +
>> > > + /* Run the link descriptor callback function */
>> > > + callback = desc->async_tx.callback;
>> > > + callback_param = desc->async_tx.callback_param;
>> > > + if (callback) {
>> > > + spin_unlock_irqrestore(&chan->lock, flags);
>> > > + callback(callback_param);
>> > > + spin_lock_irqsave(&chan->lock, flags);
>> > > + }
>> > > +
>> > > + /* Run any dependencies, then free the descriptor */
>> > > + dma_run_dependencies(&desc->async_tx);
>> > > + xilinx_dma_free_tx_descriptor(chan, desc);
>> > > + }
>> > > +
>> > > + spin_unlock_irqrestore(&chan->lock, flags); }
>> > > +
>> > > +/**
>> > > + * xilinx_dma_tx_status - Get dma transaction status
>> > > + * @dchan: DMA channel
>> > > + * @cookie: Transaction identifier
>> > > + * @txstate: Transaction state
>> > > + *
>> > > + * Return: DMA transaction status
>> > > + */
>> > > +static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
>> > > + dma_cookie_t cookie,
>> > > + struct dma_tx_state
>> > > +*txstate) {
>> > > + struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
>> > > + struct xilinx_dma_tx_descriptor *desc;
>> > > + struct xilinx_dma_tx_segment *segment;
>> > > + struct xilinx_dma_desc_hw *hw;
>> > > + enum dma_status ret;
>> > > + unsigned long flags;
>> > > + u32 residue;
>> >
>> > While compiling this threw a residue may be used uninitialized
>> > warning, I suppose 0 would be a sensible default value?
>>
>> Ok will fix it.
>>
>> > > +
>> > > + ret = dma_cookie_status(dchan, cookie, txstate);
>> > > + if (ret == DMA_COMPLETE || !txstate)
>> > > + return ret;
>> > > +
>> > > + desc = list_last_entry(&chan->active_list,
>> > > + struct xilinx_dma_tx_descriptor,
>> > > + node);
>> > > +
>> > > + spin_lock_irqsave(&chan->lock, flags);
>> > > + if (chan->has_sg) {
>> > > + while (!list_empty(&desc->segments)) {
>> > > + segment = list_first_entry(&desc->segments,
>> > > + struct xilinx_dma_tx_segment, node);
>> > > + hw = &segment->hw;
>> > > + residue += (hw->control - hw->status) &
>> > > + XILINX_DMA_MAX_TRANS_LEN;
>> > > + }
>> > > + }
>> > > +
>> > > + chan->residue = residue;
>> > > + dma_set_residue(txstate, chan->residue);
>> > > + spin_unlock_irqrestore(&chan->lock, flags);
>> > > +
>> > > + return ret;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_halt - Halt DMA channel
>> > > + * @chan: Driver specific DMA channel */ static void
>> > > +xilinx_dma_halt(struct xilinx_dma_chan *chan) {
>> > > + int loop = XILINX_DMA_LOOP_COUNT;
>> > > +
>> > > + chan->ctrl_reg &= ~XILINX_DMA_CR_RUNSTOP_MASK;
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_CONTROL,
>> > > + chan->ctrl_reg);
>> > > +
>> > > + /* Wait for the hardware to halt */
>> > > + do {
>> > > + if (dma_ctrl_read(chan, XILINX_DMA_REG_STATUS) &
>> > > + XILINX_DMA_SR_HALTED_MASK)
>> > > + break;
>> > > + } while (loop--);
>> > > +
>> > > + if (!loop) {
>> > > + dev_err(chan->dev, "Cannot stop channel %p: %x\n",
>> > > + chan, dma_ctrl_read(chan, XILINX_DMA_REG_STATUS));
>> > > + chan->err = true;
>> > > + }
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_start - Start DMA channel
>> > > + * @chan: Driver specific DMA channel */ static void
>> > > +xilinx_dma_start(struct xilinx_dma_chan *chan) {
>> > > + int loop = XILINX_DMA_LOOP_COUNT;
>> > > +
>> > > + chan->ctrl_reg |= XILINX_DMA_CR_RUNSTOP_MASK;
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_CONTROL,
>> > > + chan->ctrl_reg);
>> > > +
>> > > + /* Wait for the hardware to start */
>> > > + do {
>> > > + if (!dma_ctrl_read(chan, XILINX_DMA_REG_STATUS) &
>> > > + XILINX_DMA_SR_HALTED_MASK)
>> > > + break;
>> > > + } while (loop--);
>> > Maybe use one of the readx_poll_timeout functions?
>>
>> Ok will fix it.
>
> Seems to be the readx_poll_timeout api is not suits for my driver requirement.
> The API has some limitations when I try to use this API the code looks ugly.
>
> The issue that I am facing is:
> The readx_poll_timeout API 1st argument is expecting only the address (https://lwn.net/Articles/626525/).
> But in my case I need to pass the channel info and a particular offset in the channel.
> If I pass all these info in the API's where I am using readx_poll_timeout the code looks ugly.
>
> Do you have any other suggestions?

How about:
#define xilinx_dma_poll_timeout(chan, reg, val, cond, delay_us, timeout_us) \
readl_poll_timeout(chan->xdev->regs + reg, val, cond, delay_us, timeout_us)
>
> Regards,
> Kedar.
>
>>
>> > > +
>> > > + if (!loop) {
>> > > + dev_err(chan->dev, "Cannot start channel %p: %x\n",
>> > > + chan, dma_ctrl_read(chan, XILINX_DMA_REG_STATUS));
>> > > + chan->err = true;
>> > > + }
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_start_transfer - Starts DMA transfer
>> > > + * @chan: Driver specific channel struct pointer */ static void
>> > > +xilinx_dma_start_transfer(struct xilinx_dma_chan *chan) {
>> > > + struct xilinx_dma_tx_descriptor *head_desc, *tail_desc;
>> > > + struct xilinx_dma_tx_segment *tail_segment;
>> > > +
>> > > + if (chan->err)
>> > > + return;
>> > > +
>> > > + if (list_empty(&chan->pending_list))
>> > > + return;
>> > > +
>> > > + if (!chan->idle)
>> > > + return;
>> > > +
>> > > + head_desc = list_first_entry(&chan->pending_list,
>> > > + struct xilinx_dma_tx_descriptor, node);
>> > > + tail_desc = list_last_entry(&chan->pending_list,
>> > > + struct xilinx_dma_tx_descriptor, node);
>> > > + tail_segment = list_last_entry(&tail_desc->segments,
>> > > + struct xilinx_dma_tx_segment,
>> > > + node);
>> > > +
>> > > + if (chan->desc_pendingcount <= XILINX_DMA_COALESCE_MAX) {
>> > > + chan->ctrl_reg &= ~XILINX_DMA_CR_COALESCE_MAX;
>> > > + chan->ctrl_reg |= chan->desc_pendingcount <<
>> > > + XILINX_DMA_CR_COALESCE_SHIFT;
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_CONTROL, chan-
>> >ctrl_reg);
>> > > + }
>> > > +
>> > > + if (chan->has_sg)
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_CURDESC,
>> > > + head_desc->async_tx.phys);
>> > > +
>> > > + xilinx_dma_start(chan);
>> > > +
>> > > + if (chan->err)
>> > > + return;
>> > > +
>> > > + /* Start the transfer */
>> > > + if (chan->has_sg) {
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_TAILDESC,
>> > > + tail_segment->phys);
>> > > + } else {
>> > > + struct xilinx_dma_tx_segment *segment;
>> > > + struct xilinx_dma_desc_hw *hw;
>> > > +
>> > > + segment = list_first_entry(&head_desc->segments,
>> > > + struct xilinx_dma_tx_segment, node);
>> > > + hw = &segment->hw;
>> > > +
>> > > + if (head_desc->direction == DMA_MEM_TO_DEV)
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_SRCADDR,
>> > > + hw->buf_addr);
>> > > + else
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_DSTADDR,
>> > > + hw->buf_addr);
>> > > +
>> > > + /* Start the transfer */
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_BTT,
>> > > + hw->control & XILINX_DMA_MAX_TRANS_LEN);
>> > > + }
>> > > +
>> > > + list_splice_tail_init(&chan->pending_list, &chan->active_list);
>> > > + chan->desc_pendingcount = 0;
>> > > + chan->idle = false;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_issue_pending - Issue pending transactions
>> > > + * @dchan: DMA channel
>> > > + */
>> > > +static void xilinx_dma_issue_pending(struct dma_chan *dchan) {
>> > > + struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
>> > > + unsigned long flags;
>> > > +
>> > > + spin_lock_irqsave(&chan->lock, flags);
>> > > + xilinx_dma_start_transfer(chan);
>> > > + spin_unlock_irqrestore(&chan->lock, flags); }
>> > > +
>> > > +/**
>> > > + * xilinx_dma_complete_descriptor - Mark the active descriptor as
>> > > +complete
>> > > + * @chan : xilinx DMA channel
>> > > + */
>> > > +static void xilinx_dma_complete_descriptor(struct xilinx_dma_chan
>> > > +*chan) {
>> > > + struct xilinx_dma_tx_descriptor *desc, *next;
>> > > +
>> > > + if (list_empty(&chan->active_list))
>> > > + return;
>> > > +
>> > > + list_for_each_entry_safe(desc, next, &chan->active_list, node) {
>> > > + list_del(&desc->node);
>> > > + dma_cookie_complete(&desc->async_tx);
>> > > + list_add_tail(&desc->node, &chan->done_list);
>> > > + }
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_reset - Reset DMA channel
>> > > + * @chan: Driver specific DMA channel
>> > > + *
>> > > + * Return: '0' on success and failure value on error */ static int
>> > > +xilinx_dma_chan_reset(struct xilinx_dma_chan *chan) {
>> > > + int loop = XILINX_DMA_LOOP_COUNT;
>> > > + u32 tmp;
>> > > +
>> > > + chan->ctrl_reg = dma_ctrl_read(chan, XILINX_DMA_REG_CONTROL);
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_CONTROL, chan->ctrl_reg |
>> > > + XILINX_DMA_CR_RESET_MASK);
>> > > +
>> > > + tmp = dma_ctrl_read(chan, XILINX_DMA_REG_CONTROL) &
>> > > + XILINX_DMA_CR_RESET_MASK;
>> > > +
>> > > + /* Wait for the hardware to finish reset */
>> > > + do {
>> > > + tmp = dma_ctrl_read(chan, XILINX_DMA_REG_CONTROL) &
>> > > + XILINX_DMA_CR_RESET_MASK;
>> > > + } while (loop-- && tmp);
>> > See above
>>
>> Ok will fix it.
>>
>> Regards,
>> Kedar.
>>
>> > > +
>> > > + if (!loop) {
>> > > + dev_err(chan->dev, "reset timeout, cr %x, sr %x\n",
>> > > + dma_ctrl_read(chan, XILINX_DMA_REG_CONTROL),
>> > > + dma_ctrl_read(chan, XILINX_DMA_REG_STATUS));
>> > > + return -EBUSY;
>> > > + }
>> > > +
>> > > + chan->err = false;
>> > > +
>> > > + return 0;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_irq_handler - DMA Interrupt handler
>> > > + * @irq: IRQ number
>> > > + * @data: Pointer to the Xilinx DMA channel structure
>> > > + *
>> > > + * Return: IRQ_HANDLED/IRQ_NONE
>> > > + */
>> > > +static irqreturn_t xilinx_dma_irq_handler(int irq, void *data) {
>> > > + struct xilinx_dma_chan *chan = data;
>> > > + u32 status;
>> > > +
>> > > + /* Read the status and ack the interrupts. */
>> > > + status = dma_ctrl_read(chan, XILINX_DMA_REG_STATUS);
>> > > + if (!(status & XILINX_DMA_XR_IRQ_ALL_MASK))
>> > > + return IRQ_NONE;
>> > > +
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_STATUS,
>> > > + status & XILINX_DMA_XR_IRQ_ALL_MASK);
>> > > +
>> > > + if (status & XILINX_DMA_XR_IRQ_ERROR_MASK) {
>> > > + dev_err(chan->dev,
>> > > + "Channel %p has errors %x, cdr %x tdr %x\n",
>> > > + chan, dma_ctrl_read(chan, XILINX_DMA_REG_STATUS),
>> > > + dma_ctrl_read(chan, XILINX_DMA_REG_CURDESC),
>> > > + dma_ctrl_read(chan, XILINX_DMA_REG_TAILDESC));
>> > > + chan->err = true;
>> > > + }
>> > > +
>> > > + /*
>> > > + * Device takes too long to do the transfer when user requires
>> > > + * responsiveness
>> > > + */
>> > > + if (status & XILINX_DMA_XR_IRQ_DELAY_MASK)
>> > > + dev_dbg(chan->dev, "Inter-packet latency too
>> > > + long\n");
>> > > +
>> > > + if (status & XILINX_DMA_XR_IRQ_IOC_MASK) {
>> > > + spin_lock(&chan->lock);
>> > > + xilinx_dma_complete_descriptor(chan);
>> > > + chan->idle = true;
>> > > + xilinx_dma_start_transfer(chan);
>> > > + spin_unlock(&chan->lock);
>> > > + }
>> > > +
>> > > + tasklet_schedule(&chan->tasklet);
>> > > + return IRQ_HANDLED;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_do_tasklet - Schedule completion tasklet
>> > > + * @data: Pointer to the Xilinx dma channel structure */ static
>> > > +void xilinx_dma_do_tasklet(unsigned long data) {
>> > > + struct xilinx_dma_chan *chan = (struct xilinx_dma_chan
>> > > +*)data;
>> > > +
>> > > + xilinx_dma_chan_desc_cleanup(chan);
>> > > +}
>> > > +
>> > > +/**
>> > > + * append_desc_queue - Queuing descriptor
>> > > + * @chan: Driver specific dma channel
>> > > + * @desc: dma transaction descriptor */ static void
>> > > +append_desc_queue(struct xilinx_dma_chan *chan,
>> > > + struct xilinx_dma_tx_descriptor *desc) {
>> > > + struct xilinx_dma_tx_segment *tail_segment;
>> > > + struct xilinx_dma_tx_descriptor *tail_desc;
>> > > +
>> > > + if (list_empty(&chan->pending_list))
>> > > + goto append;
>> > > +
>> > > + /*
>> > > + * Add the hardware descriptor to the chain of hardware descriptors
>> > > + * that already exists in memory.
>> > > + */
>> > > + tail_desc = list_last_entry(&chan->pending_list,
>> > > + struct xilinx_dma_tx_descriptor, node);
>> > > + tail_segment = list_last_entry(&tail_desc->segments,
>> > > + struct xilinx_dma_tx_segment, node);
>> > > + tail_segment->hw.next_desc = (u32)desc->async_tx.phys;
>> > > +
>> > > + /*
>> > > + * Add the software descriptor and all children to the list
>> > > + * of pending transactions
>> > > + */
>> > > +append:
>> > > + list_add_tail(&desc->node, &chan->pending_list);
>> > > + chan->desc_pendingcount++;
>> > > +
>> > > + if (unlikely(chan->desc_pendingcount > XILINX_DMA_COALESCE_MAX))
>> {
>> > > + dev_dbg(chan->dev, "desc pendingcount is too high\n");
>> > > + chan->desc_pendingcount = XILINX_DMA_COALESCE_MAX;
>> > > + BUG();
>> > > + }
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_tx_submit - Submit DMA transaction
>> > > + * @tx: Async transaction descriptor
>> > > + *
>> > > + * Return: cookie value on success and failure value on error */
>> > > +static dma_cookie_t xilinx_dma_tx_submit(struct
>> > > +dma_async_tx_descriptor *tx) {
>> > > + struct xilinx_dma_tx_descriptor *desc = to_dma_tx_descriptor(tx);
>> > > + struct xilinx_dma_chan *chan = to_xilinx_chan(tx->chan);
>> > > + dma_cookie_t cookie;
>> > > + unsigned long flags;
>> > > + int err;
>> > > +
>> > > + if (chan->err) {
>> > > + /*
>> > > + * If reset fails, need to hard reset the system.
>> > > + * Channel is no longer functional
>> > > + */
>> > > + err = xilinx_dma_chan_reset(chan);
>> > > + if (err < 0)
>> > > + return err;
>> > > + }
>> > > +
>> > > + spin_lock_irqsave(&chan->lock, flags);
>> > > +
>> > > + cookie = dma_cookie_assign(tx);
>> > > +
>> > > + /* Put this transaction onto the tail of the pending queue */
>> > > + append_desc_queue(chan, desc);
>> > > +
>> > > + spin_unlock_irqrestore(&chan->lock, flags);
>> > > +
>> > > + return cookie;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_prep_slave_sg - prepare descriptors for a DMA_SLAVE
>> > > +transaction
>> > > + * @dchan: DMA channel
>> > > + * @sgl: scatterlist to transfer to/from
>> > > + * @sg_len: number of entries in @scatterlist
>> > > + * @direction: DMA direction
>> > > + * @flags: transfer ack flags
>> > > + * @context: APP words of the descriptor
>> > > + *
>> > > + * Return: Async transaction descriptor on success and NULL on
>> > > +failure */ static struct dma_async_tx_descriptor
>> > > +*xilinx_dma_prep_slave_sg(
>> > > + struct dma_chan *dchan, struct scatterlist *sgl, unsigned int sg_len,
>> > > + enum dma_transfer_direction direction, unsigned long flags,
>> > > + void *context)
>> > > +{
>> > > + struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
>> > > + struct xilinx_dma_tx_descriptor *desc;
>> > > + struct xilinx_dma_tx_segment *segment;
>> > > + u32 *app_w = (u32 *)context;
>> > > + struct scatterlist *sg;
>> > > + size_t copy, sg_used;
>> > > + int i;
>> > > +
>> > > + if (!is_slave_direction(direction))
>> > > + return NULL;
>> > > +
>> > > + /* Allocate a transaction descriptor. */
>> > > + desc = xilinx_dma_alloc_tx_descriptor(chan);
>> > > + if (!desc)
>> > > + return NULL;
>> > > +
>> > > + desc->direction = direction;
>> > > + dma_async_tx_descriptor_init(&desc->async_tx, &chan->common);
>> > > + desc->async_tx.tx_submit = xilinx_dma_tx_submit;
>> > > +
>> > > + /* Build transactions using information in the scatter gather list */
>> > > + for_each_sg(sgl, sg, sg_len, i) {
>> > > + sg_used = 0;
>> > > +
>> > > + /* Loop until the entire scatterlist entry is used */
>> > > + while (sg_used < sg_dma_len(sg)) {
>> > > + struct xilinx_dma_desc_hw *hw;
>> > > +
>> > > + /* Get a free segment */
>> > > + segment = xilinx_dma_alloc_tx_segment(chan);
>> > > + if (!segment)
>> > > + goto error;
>> > > +
>> > > + /*
>> > > + * Calculate the maximum number of bytes to transfer,
>> > > + * making sure it is less than the hw limit
>> > > + */
>> > > + copy = min_t(size_t, sg_dma_len(sg) - sg_used,
>> > > + XILINX_DMA_MAX_TRANS_LEN);
>> > > + hw = &segment->hw;
>> > > +
>> > > + /* Fill in the descriptor */
>> > > + hw->buf_addr = sg_dma_address(sg) + sg_used;
>> > > +
>> > > + hw->control = copy;
>> > > +
>> > > + if (direction == DMA_MEM_TO_DEV) {
>> > > + if (app_w)
>> > > + memcpy(hw->app, app_w, sizeof(u32) *
>> > > + XILINX_DMA_NUM_APP_WORDS);
>> > > + }
>> > > +
>> > > + sg_used += copy;
>> > > +
>> > > + /*
>> > > + * Insert the segment into the descriptor segments
>> > > + * list.
>> > > + */
>> > > + list_add_tail(&segment->node, &desc->segments);
>> > > + }
>> > > + }
>> > > +
>> > > + segment = list_first_entry(&desc->segments,
>> > > + struct xilinx_dma_tx_segment, node);
>> > > + desc->async_tx.phys = segment->phys;
>> > > +
>> > > + /* For the last DMA_MEM_TO_DEV transfer, set EOP */
>> > > + if (direction == DMA_MEM_TO_DEV) {
>> > > + segment->hw.control |= XILINX_DMA_BD_SOP;
>> > > + segment = list_last_entry(&desc->segments,
>> > > + struct xilinx_dma_tx_segment,
>> > > + node);
>> > > + segment->hw.control |= XILINX_DMA_BD_EOP;
>> > > + }
>> > > +
>> > > + return &desc->async_tx;
>> > > +
>> > > +error:
>> > > + xilinx_dma_free_tx_descriptor(chan, desc);
>> > > + return NULL;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_terminate_all - Halt the channel and free descriptors
>> > > + * @dchan: DMA Channel pointer
>> > > + *
>> > > + * Return: '0' always
>> > > + */
>> > > +static int xilinx_dma_terminate_all(struct dma_chan *dchan) {
>> > > + struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
>> > > +
>> > > + /* Halt the DMA engine */
>> > > + xilinx_dma_halt(chan);
>> > > +
>> > > + /* Remove and free all of the descriptors in the lists */
>> > > + xilinx_dma_free_descriptors(chan);
>> > > +
>> > > + return 0;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_chan_remove - Per Channel remove function
>> > > + * @chan: Driver specific DMA channel */ static void
>> > > +xilinx_dma_chan_remove(struct xilinx_dma_chan *chan) {
>> > > + /* Disable interrupts */
>> > > + chan->ctrl_reg &= ~XILINX_DMA_XR_IRQ_ALL_MASK;
>> > > + dma_ctrl_write(chan, XILINX_DMA_REG_CONTROL,
>> > > +chan->ctrl_reg);
>> > > +
>> > > + if (chan->irq > 0)
>> > > + free_irq(chan->irq, chan);
>> > > +
>> > > + tasklet_kill(&chan->tasklet);
>> > > +
>> > > + list_del(&chan->common.device_node);
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_chan_probe - Per Channel Probing
>> > > + * It get channel features from the device tree entry and
>> > > + * initialize special channel handling routines
>> > > + *
>> > > + * @xdev: Driver specific device structure
>> > > + * @node: Device node
>> > > + *
>> > > + * Return: '0' on success and failure value on error */ static int
>> > > +xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
>> > > + struct device_node *node) {
>> > > + struct xilinx_dma_chan *chan;
>> > > + int err;
>> > > + bool has_dre;
>> > > + u32 value, width = 0;
>> > > +
>> > > + /* alloc channel */
>> > > + chan = devm_kzalloc(xdev->dev, sizeof(*chan), GFP_KERNEL);
>> > > + if (!chan)
>> > > + return -ENOMEM;
>> > > +
>> > > + chan->dev = xdev->dev;
>> > > + chan->xdev = xdev;
>> > > + chan->has_sg = xdev->has_sg;
>> > > + chan->desc_pendingcount = 0x0;
>> > > +
>> > > + has_dre = of_property_read_bool(node, "xlnx,include-dre");
>> > > +
>> > > + err = of_property_read_u32(node, "xlnx,datawidth", &value);
>> > > + if (err) {
>> > > + dev_err(xdev->dev, "unable to read datawidth property");
>> > > + return err;
>> > > + }
>> > > +
>> > > + width = value >> 3; /* Convert bits to bytes */
>> > > +
>> > > + /* If data width is greater than 8 bytes, DRE is not in hw */
>> > > + if (width > 8)
>> > > + has_dre = false;
>> > > +
>> > > + if (!has_dre)
>> > > + xdev->common.copy_align = fls(width - 1);
>> > > +
>> > > + if (of_device_is_compatible(node, "xlnx,axi-dma-mm2s-channel")) {
>> > > + chan->id = 0;
>> > > + chan->ctrl_offset = XILINX_DMA_MM2S_CTRL_OFFSET;
>> > > + } else if (of_device_is_compatible(node, "xlnx,axi-dma-s2mm-
>> channel")) {
>> > > + chan->id = 1;
>> > > + chan->ctrl_offset = XILINX_DMA_S2MM_CTRL_OFFSET;
>> > > + } else {
>> > > + dev_err(xdev->dev, "Invalid channel compatible node\n");
>> > > + return -EINVAL;
>> > > + }
>> > > +
>> > > + xdev->chan[chan->id] = chan;
>> > > +
>> > > + /* Initialize the channel */
>> > > + err = xilinx_dma_chan_reset(chan);
>> > > + if (err) {
>> > > + dev_err(xdev->dev, "Reset channel failed\n");
>> > > + return err;
>> > > + }
>> > > +
>> > > + spin_lock_init(&chan->lock);
>> > > + INIT_LIST_HEAD(&chan->pending_list);
>> > > + INIT_LIST_HEAD(&chan->done_list);
>> > > + INIT_LIST_HEAD(&chan->active_list);
>> > > + INIT_LIST_HEAD(&chan->free_seg_list);
>> > > +
>> > > + chan->common.device = &xdev->common;
>> > > +
>> > > + /* find the IRQ line, if it exists in the device tree */
>> > > + chan->irq = irq_of_parse_and_map(node, 0);
>> > > + err = request_irq(chan->irq, xilinx_dma_irq_handler,
>> > > + IRQF_SHARED,
>> > > + "xilinx-dma-controller", chan);
>> > > + if (err) {
>> > > + dev_err(xdev->dev, "unable to request IRQ %d\n", chan->irq);
>> > > + return err;
>> > > + }
>> > > +
>> > > + /* Initialize the tasklet */
>> > > + tasklet_init(&chan->tasklet, xilinx_dma_do_tasklet,
>> > > + (unsigned long)chan);
>> > > +
>> > > + /* Add the channel to DMA device channel list */
>> > > + list_add_tail(&chan->common.device_node,
>> > > + &xdev->common.channels);
>> > > +
>> > > + chan->idle = true;
>> > > +
>> > > + return 0;
>> > > +}
>> > > +
>> > > +/**
>> > > + * of_dma_xilinx_xlate - Translation function
>> > > + * @dma_spec: Pointer to DMA specifier as found in the device tree
>> > > + * @ofdma: Pointer to DMA controller data
>> > > + *
>> > > + * Return: DMA channel pointer on success and NULL on error */
>> > > +static struct dma_chan *of_dma_xilinx_xlate(struct of_phandle_args
>> > *dma_spec,
>> > > + struct of_dma *ofdma) {
>> > > + struct xilinx_dma_device *xdev = ofdma->of_dma_data;
>> > > + int chan_id = dma_spec->args[0];
>> > > +
>> > > + if (chan_id >= XILINX_DMA_MAX_CHANS_PER_DEVICE)
>> > > + return NULL;
>> > > +
>> > > + return dma_get_slave_channel(&xdev->chan[chan_id]->common);
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_probe - Driver probe function
>> > > + * @pdev: Pointer to the platform_device structure
>> > > + *
>> > > + * Return: '0' on success and failure value on error */ static int
>> > > +xilinx_dma_probe(struct platform_device *pdev) {
>> > > + struct xilinx_dma_device *xdev;
>> > > + struct device_node *child, *node;
>> > > + struct resource *res;
>> > > + int i, ret;
>> > > +
>> > > + xdev = devm_kzalloc(&pdev->dev, sizeof(*xdev), GFP_KERNEL);
>> > > + if (!xdev)
>> > > + return -ENOMEM;
>> > > +
>> > > + xdev->dev = &(pdev->dev);
>> > > + INIT_LIST_HEAD(&xdev->common.channels);
>> > > +
>> > > + node = pdev->dev.of_node;
>> > > +
>> > > + /* Map the registers */
>> > > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> > > + xdev->regs = devm_ioremap_resource(&pdev->dev, res);
>> > > + if (IS_ERR(xdev->regs))
>> > > + return PTR_ERR(xdev->regs);
>> > > +
>> > > + /* Check if SG is enabled */
>> > > + xdev->has_sg = of_property_read_bool(node,
>> > > + "xlnx,include-sg");
>> > > +
>> > > + /* Axi DMA only do slave transfers */
>> > > + dma_cap_set(DMA_SLAVE, xdev->common.cap_mask);
>> > > + dma_cap_set(DMA_PRIVATE, xdev->common.cap_mask);
>> > > + xdev->common.device_prep_slave_sg = xilinx_dma_prep_slave_sg;
>> > > + xdev->common.device_terminate_all = xilinx_dma_terminate_all;
>> > > + xdev->common.device_issue_pending = xilinx_dma_issue_pending;
>> > > + xdev->common.device_alloc_chan_resources =
>> > > + xilinx_dma_alloc_chan_resources;
>> > > + xdev->common.device_free_chan_resources =
>> > > + xilinx_dma_free_chan_resources;
>> > > + xdev->common.device_tx_status = xilinx_dma_tx_status;
>> > > + xdev->common.directions = BIT(DMA_DEV_TO_MEM) |
>> > BIT(DMA_MEM_TO_DEV);
>> > > + xdev->common.residue_granularity =
>> > DMA_RESIDUE_GRANULARITY_SEGMENT;
>> > > + xdev->common.dev = &pdev->dev;
>> > > +
>> > > + platform_set_drvdata(pdev, xdev);
>> > > +
>> > > + for_each_child_of_node(node, child) {
>> > > + ret = xilinx_dma_chan_probe(xdev, child);
>> > > + if (ret) {
>> > > + dev_err(&pdev->dev, "Probing channels failed\n");
>> > > + goto free_chan_resources;
>> > > + }
>> > > + }
>> > > +
>> > > + dma_async_device_register(&xdev->common);
>> > > +
>> > > + ret = of_dma_controller_register(node, of_dma_xilinx_xlate, xdev);
>> > > + if (ret) {
>> > > + dev_err(&pdev->dev, "Unable to register DMA to DT\n");
>> > > + dma_async_device_unregister(&xdev->common);
>> > > + goto free_chan_resources;
>> > > + }
>> > > +
>> > > + dev_info(&pdev->dev, "Xilinx AXI DMA Engine driver
>> > > + Probed!!\n");
>> > > +
>> > > + return 0;
>> > > +
>> > > +free_chan_resources:
>> > > + for (i = 0; i < XILINX_DMA_MAX_CHANS_PER_DEVICE; i++)
>> > > + if (xdev->chan[i])
>> > > + xilinx_dma_chan_remove(xdev->chan[i]);
>> > > +
>> > > + return ret;
>> > > +}
>> > > +
>> > > +/**
>> > > + * xilinx_dma_remove - Driver remove function
>> > > + * @pdev: Pointer to the platform_device structure
>> > > + *
>> > > + * Return: Always '0'
>> > > + */
>> > > +static int xilinx_dma_remove(struct platform_device *pdev) {
>> > > + struct xilinx_dma_device *xdev = platform_get_drvdata(pdev);
>> > > + int i;
>> > > +
>> > > + of_dma_controller_free(pdev->dev.of_node);
>> > > + dma_async_device_unregister(&xdev->common);
>> > > +
>> > > + for (i = 0; i < XILINX_DMA_MAX_CHANS_PER_DEVICE; i++)
>> > > + if (xdev->chan[i])
>> > > + xilinx_dma_chan_remove(xdev->chan[i]);
>> > > +
>> > > + return 0;
>> > > +}
>> > > +
>> > > +static const struct of_device_id xilinx_dma_of_match[] = {
>> > > + { .compatible = "xlnx,axi-dma-1.00.a",},
>> > > + {}
>> > > +};
>> > > +MODULE_DEVICE_TABLE(of, xilinx_dma_of_match);
>> > > +
>> > > +static struct platform_driver xilinx_dma_driver = {
>> > > + .driver = {
>> > > + .name = "xilinx-dma",
>> > > + .of_match_table = xilinx_dma_of_match,
>> > > + },
>> > > + .probe = xilinx_dma_probe,
>> > > + .remove = xilinx_dma_remove, };
>> > > +
>> > > +module_platform_driver(xilinx_dma_driver);
>> > > +
>> > > +MODULE_AUTHOR("Xilinx, Inc.");
>> > > +MODULE_DESCRIPTION("Xilinx DMA driver"); MODULE_LICENSE("GPL");
>> > > --
>> > > 2.1.2
>> > >
>> > >
>> > > _______________________________________________
>> > > linux-arm-kernel mailing list
>> > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
>> > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>> >
>> > Cheers,
>> >
>> > Moritz

Thanks,
Moritz
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