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Message-ID: <CAAtXAHf9S662okN1gchbD246=e4_bMFoyBMrbt5q48xm1uo_CA@mail.gmail.com>
Date: Wed, 19 Aug 2015 14:51:28 -0700
From: Moritz Fischer <moritz.fischer@...us.com>
To: Kedareswara rao Appana <appana.durga.rao@...inx.com>
Cc: vinod.koul@...el.com, dan.j.williams@...el.com,
Michal Simek <michal.simek@...inx.com>,
Sören Brinkmann <soren.brinkmann@...inx.com>,
appanad@...inx.com, anirudha@...inx.com, dmaengine@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
Srikanth Thokala <sthokal@...inx.com>
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@...inx.com> 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@...inx.com>
> Signed-off-by: Kedareswara rao Appana <appanad@...inx.com>
> ---
> The deivce tree doc got applied in the slave-dmaengine.git.
>
> Forgot to include dmaengine@...r.kernel.org 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?
> +}
> +
> +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?
> +
> + 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?
> +
> + 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
> +
> + 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@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Cheers,
Moritz
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