From: Appana Durga Kedareswara Rao <appana.durga.rao@xilinx.com>
To: Appana Durga Kedareswara Rao <appanad@xilinx.com>,
        "dan.j.williams@intel.com" <dan.j.williams@intel.com>,
        "vinod.koul@intel.com" <vinod.koul@intel.com>,
        Michal Simek <michals@xilinx.com>, Soren Brinkmann <sorenb@xilinx.com>,
        Punnaiah Choudary Kalluri <punnaia@xilinx.com>
CC: "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Srikanth Thokala <sthokal@xilinx.com>
Subject: RE: [PATCH v4 2/2] dma: Add Xilinx AXI Central Direct Memory Access
 Engine driver support
Thread-Topic: [PATCH v4 2/2] dma: Add Xilinx AXI Central Direct Memory
 Access Engine driver support
Thread-Index: AQHQk+ifunhHEWKwskKhtju6n/V9QZ2aY2Bw
Date: Wed, 3 Jun 2015 06:22:39 +0000
Message-ID: <C246CAC1457055469EF09E3A7AC4E11A49A8B5D3@XAP-PVEXMBX01.xlnx.xilinx.com>
References: <1432228035-6569-1-git-send-email-appanad@xilinx.com>
In-Reply-To: <1432228035-6569-1-git-send-email-appanad@xilinx.com>
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Ping!

> -----Original Message-----
> From: Kedareswara rao Appana [mailto:appana.durga.rao@xilinx.com]
> Sent: Thursday, May 21, 2015 10:37 PM
> To: dan.j.williams@intel.com; vinod.koul@intel.com; Michal Simek; Soren
> Brinkmann; Appana Durga Kedareswara Rao; Punnaiah Choudary Kalluri
> Cc: dmaengine@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> kernel@vger.kernel.org; Srikanth Thokala
> Subject: [PATCH v4 2/2] dma: Add Xilinx AXI Central Direct Memory Access
> Engine driver support
>
> This is the driver for the AXI Central Direct Memory Access (AXI
> CDMA) core, which is a soft Xilinx IP core that provides high-bandwidth Direct
> Memory Access (DMA) between a memory-mapped source address and a
> memory-mapped destination address.
>
> This module works on Zynq (ARM Based SoC) and Microblaze platforms.
>
> Signed-off-by: Srikanth Thokala <sthokal@xilinx.com>
> Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
> ---
> This patch is rebased on the commit
> Merge tag 'nfs-for-4.1-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
>
> Changes in v4:
> - used GFP_NOWAIT instead of GFP_KERNEL during the desc allocation
> - Modified spin_lock handling moved the spin_lock to the appropriate
> functions
> - device_control api is removed and updated driver as per newer APi's.
> Changes in v3:
> - Check for CDMA idle condition before changing the configuration.
> - Modified the xilinx_dma.h header file location to the
>   include/linux/dma/xilinx_dma.h
> Changes in v2:
> - Rebased on 3.16-rc7.
>
>  drivers/dma/Kconfig              |  12 +
>  drivers/dma/xilinx/Makefile      |   1 +
>  drivers/dma/xilinx/xilinx_cdma.c | 987
> +++++++++++++++++++++++++++++++++++++++
>  include/linux/dma/xilinx_dma.h   |  15 +-
>  4 files changed, 1014 insertions(+), 1 deletion(-)  create mode 100644
> drivers/dma/xilinx/xilinx_cdma.c
>
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig index
> bda2cb0..c42cf24 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -492,4 +492,16 @@ 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_CDMA
> +        tristate "Xilinx AXI CDMA Engine"
> +        depends on (ARCH_ZYNQ || MICROBLAZE)
> +     select DMA_ENGINE
> +     help
> +          Enable support for Xilinx AXI CDMA Soft IP.
> +
> +          The AXI CDMA is a soft IP which provides high-bandwidth
> +          Direct Memory Access (DMA) between a memory-mapped source
> +          address and a memory-mapped destination address using the
> +          AXI4 protocol.
> +
>  endif
> diff --git a/drivers/dma/xilinx/Makefile b/drivers/dma/xilinx/Makefile index
> 3c4e9f2..f909d34 100644
> --- a/drivers/dma/xilinx/Makefile
> +++ b/drivers/dma/xilinx/Makefile
> @@ -1 +1,2 @@
>  obj-$(CONFIG_XILINX_VDMA) += xilinx_vdma.o
> +obj-$(CONFIG_XILINX_VDMA) += xilinx_cdma.o
> diff --git a/drivers/dma/xilinx/xilinx_cdma.c
> b/drivers/dma/xilinx/xilinx_cdma.c
> new file mode 100644
> index 0000000..eda443a
> --- /dev/null
> +++ b/drivers/dma/xilinx/xilinx_cdma.c
> @@ -0,0 +1,987 @@
> +/*
> + * DMA driver for Xilinx Central DMA Engine
> + *
> + * Copyright (C) 2010 - 2015 Xilinx, Inc. All rights reserved.
> + *
> + * Based on the Freescale DMA driver.
> + *
> + * Description:
> + *  The AXI CDMA, is a soft IP, which provides high-bandwidth Direct
> +Memory
> + *  Access (DMA) between a memory-mapped source address and a
> +memory-mapped
> + *  destination address.
> + *
> + * This program 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/dmapool.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_CDMA_CONTROL_OFFSET     0x00
> +#define XILINX_CDMA_STATUS_OFFSET      0x04
> +#define XILINX_CDMA_CDESC_OFFSET       0x08
> +#define XILINX_CDMA_TDESC_OFFSET       0x10
> +#define XILINX_CDMA_SRCADDR_OFFSET     0x18
> +#define XILINX_CDMA_DSTADDR_OFFSET     0x20
> +#define XILINX_CDMA_BTT_OFFSET         0x28
> +
> +/* General register bits definitions */
> +#define XILINX_CDMA_CR_RESET           BIT(2)
> +#define XILINX_CDMA_CR_SGMODE          BIT(3)
> +
> +#define XILINX_CDMA_SR_IDLE            BIT(1)
> +
> +#define XILINX_CDMA_XR_IRQ_IOC_MASK    BIT(12)
> +#define XILINX_CDMA_XR_IRQ_DELAY_MASK  BIT(13) #define
> +XILINX_CDMA_XR_IRQ_ERROR_MASK  BIT(14)
> +#define XILINX_CDMA_XR_IRQ_ALL_MASK    GENMASK(14, 12)
> +
> +#define XILINX_CDMA_XR_DELAY_MASK      GENMASK(31, 24)
> +#define XILINX_CDMA_XR_COALESCE_MASK   GENMASK(23, 16)
> +
> +#define XILINX_CDMA_DELAY_MAX          GENMASK(7, 0)
> +#define XILINX_CDMA_DELAY_SHIFT                24
> +
> +#define XILINX_CDMA_COALESCE_MAX       GENMASK(7, 0)
> +#define XILINX_CDMA_COALESCE_SHIFT     16
> +
> +/* Delay loop counter to prevent hardware failure */
> +#define XILINX_CDMA_RESET_LOOP         1000000
> +
> +/* Maximum transfer length */
> +#define XILINX_CDMA_MAX_TRANS_LEN      GENMASK(22, 0)
> +
> +/**
> + * struct xilinx_cdma_desc_hw - Hardware Descriptor
> + * @next_desc: Next Descriptor Pointer @0x00
> + * @pad1: Reserved @0x04
> + * @src_addr: Source address @0x08
> + * @pad2: Reserved @0x0C
> + * @dest_addr: Destination address @0x10
> + * @pad3: Reserved @0x14
> + * @control: Control field @0x18
> + * @status: Status field @0x1C
> + */
> +struct xilinx_cdma_desc_hw {
> +     u32 next_desc;
> +     u32 pad1;
> +     u32 src_addr;
> +     u32 pad2;
> +     u32 dest_addr;
> +     u32 pad3;
> +     u32 control;
> +     u32 status;
> +} __aligned(64);
> +
> +/**
> + * struct xilinx_cdma_tx_segment - Descriptor segment
> + * @hw: Hardware descriptor
> + * @node: Node in the descriptor segments list
> + * @phys: Physical address of segment
> + */
> +struct xilinx_cdma_tx_segment {
> +     struct xilinx_cdma_desc_hw hw;
> +     struct list_head node;
> +     dma_addr_t phys;
> +} __aligned(64);
> +
> +/**
> + * struct xilinx_cdma_tx_descriptor - Per Transaction structure
> + * @async_tx: Async transaction descriptor
> + * @segments: TX segments list
> + * @node: Node in the channel descriptors list  */ struct
> +xilinx_cdma_tx_descriptor {
> +     struct dma_async_tx_descriptor async_tx;
> +     struct list_head segments;
> +     struct list_head node;
> +};
> +
> +/**
> + * struct xilinx_cdma_chan - Driver specific cdma channel structure
> + * @xdev: Driver specific device structure
> + * @lock: Descriptor operation lock
> + * @done_list: Complete descriptors
> + * @pending_list: Descriptors waiting
> + * @active_desc: Active descriptor
> + * @common: DMA common channel
> + * @desc_pool: Descriptors pool
> + * @dev: The dma device
> + * @irq: Channel IRQ
> + * @has_sg: Support scatter transfers
> + * @err: Channel has errors
> + * @idle: Channel status
> + * @tasklet: Cleanup work after irq
> + */
> +struct xilinx_cdma_chan {
> +     struct xilinx_cdma_device *xdev;
> +     spinlock_t lock;
> +     struct list_head done_list;
> +     struct list_head pending_list;
> +     struct xilinx_cdma_tx_descriptor *active_desc;
> +     struct dma_chan common;
> +     struct dma_pool *desc_pool;
> +     struct device *dev;
> +     int irq;
> +     bool has_sg;
> +     int err;
> +     bool idle;
> +     struct tasklet_struct tasklet;
> +};
> +
> +/**
> + * struct xilinx_cdma_device - CDMA device structure
> + * @regs: I/O mapped base address
> + * @dev: Device Structure
> + * @common: DMA device structure
> + * @chan: Driver specific cdma channel
> + * @has_sg: Specifies whether Scatter-Gather is present or not  */
> +struct xilinx_cdma_device {
> +     void __iomem *regs;
> +     struct device *dev;
> +     struct dma_device common;
> +     struct xilinx_cdma_chan *chan;
> +     bool has_sg;
> +};
> +
> +/* Macros */
> +#define to_xilinx_chan(chan) \
> +     container_of(chan, struct xilinx_cdma_chan, common) #define
> +to_cdma_tx_descriptor(tx) \
> +     container_of(tx, struct xilinx_cdma_tx_descriptor, async_tx)
> +
> +/* IO accessors */
> +static inline void cdma_write(struct xilinx_cdma_chan *chan, u32 reg,
> +u32 val) {
> +     writel(val, chan->xdev->regs + reg);
> +}
> +
> +static inline u32 cdma_read(struct xilinx_cdma_chan *chan, u32 reg) {
> +     return readl(chan->xdev->regs + reg);
> +}
> +
> +static inline void cdma_ctrl_clr(struct xilinx_cdma_chan *chan, u32 reg,
> +                             u32 clr)
> +{
> +     cdma_write(chan, reg, cdma_read(chan, reg) & ~clr); }
> +
> +static inline void cdma_ctrl_set(struct xilinx_cdma_chan *chan, u32 reg,
> +                             u32 set)
> +{
> +     cdma_write(chan, reg, cdma_read(chan, reg) | set); }
> +
> +/*
> +-----------------------------------------------------------------------
> +------
> + * Descriptors and segments alloc and free  */
> +
> +/**
> + * xilinx_cdma_alloc_tx_segment - Allocate transaction segment
> + * @chan: Driver specific cdma channel
> + *
> + * Return: The allocated segment on success and NULL on failure.
> + */
> +static struct xilinx_cdma_tx_segment *
> +xilinx_cdma_alloc_tx_segment(struct xilinx_cdma_chan *chan) {
> +     struct xilinx_cdma_tx_segment *segment;
> +     dma_addr_t phys;
> +
> +     segment = dma_pool_alloc(chan->desc_pool, GFP_ATOMIC, &phys);
> +     if (!segment)
> +             return NULL;
> +
> +     memset(segment, 0, sizeof(*segment));
> +     segment->phys = phys;
> +
> +     return segment;
> +}
> +
> +/**
> + * xilinx_cdma_free_tx_segment - Free transaction segment
> + * @chan: Driver specific cdma channel
> + * @segment: cdma transaction segment
> + */
> +static void xilinx_cdma_free_tx_segment(struct xilinx_cdma_chan *chan,
> +                                     struct xilinx_cdma_tx_segment
> *segment) {
> +     dma_pool_free(chan->desc_pool, segment, segment->phys); }
> +
> +/**
> + * xilinx_cdma_tx_descriptor - Allocate transaction descriptor
> + * @chan: Driver specific cdma channel
> + *
> + * Return: The allocated descriptor on success and NULL on failure.
> + */
> +static struct xilinx_cdma_tx_descriptor *
> +xilinx_cdma_alloc_tx_descriptor(struct xilinx_cdma_chan *chan) {
> +     struct xilinx_cdma_tx_descriptor *desc;
> +
> +     desc = kzalloc(sizeof(*desc), GFP_KERNEL);
> +     if (!desc)
> +             return NULL;
> +
> +     INIT_LIST_HEAD(&desc->segments);
> +
> +     return desc;
> +}
> +
> +/**
> + * xilinx_cdma_free_tx_descriptor - Free transaction descriptor
> + * @chan: Driver specific cdma channel
> + * @desc: cdma transaction descriptor
> + */
> +static void
> +xilinx_cdma_free_tx_descriptor(struct xilinx_cdma_chan *chan,
> +                            struct xilinx_cdma_tx_descriptor *desc) {
> +     struct xilinx_cdma_tx_segment *segment, *next;
> +
> +     if (!desc)
> +             return;
> +
> +     list_for_each_entry_safe(segment, next, &desc->segments, node) {
> +             list_del(&segment->node);
> +             xilinx_cdma_free_tx_segment(chan, segment);
> +     }
> +
> +     kfree(desc);
> +}
> +
> +/**
> + * xilinx_cdma_alloc_chan_resources - Allocate channel resources
> + * @dchan: DMA channel
> + *
> + * Return: '0' on success and failure value on error  */ static int
> +xilinx_cdma_alloc_chan_resources(struct dma_chan *dchan) {
> +     struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
> +
> +     /* Has this channel already been allocated? */
> +     if (chan->desc_pool)
> +             return 0;
> +
> +     /*
> +      * We need the descriptor to be aligned to 64bytes
> +      * for meeting Xilinx DMA specification requirement.
> +      */
> +     chan->desc_pool = dma_pool_create("xilinx_cdma_desc_pool",
> +                             chan->dev,
> +                             sizeof(struct xilinx_cdma_tx_segment),
> +                             __alignof__(struct
> xilinx_cdma_tx_segment), 0);
> +     if (!chan->desc_pool) {
> +             dev_err(chan->dev,
> +                     "unable to allocate channel descriptor pool\n");
> +             return -ENOMEM;
> +     }
> +
> +     dma_cookie_init(dchan);
> +     return 0;
> +}
> +
> +/**
> + * xilinx_cdma_free_desc_list - Free descriptors list
> + * @chan: Driver specific cdma channel
> + * @list: List to parse and delete the descriptor  */ static void
> +xilinx_cdma_free_desc_list(struct xilinx_cdma_chan *chan,
> +                                    struct list_head *list)
> +{
> +     struct xilinx_cdma_tx_descriptor *desc, *next;
> +
> +     list_for_each_entry_safe(desc, next, list, node) {
> +             list_del(&desc->node);
> +             xilinx_cdma_free_tx_descriptor(chan, desc);
> +     }
> +}
> +
> +/**
> + * xilinx_cdma_free_chan_resources - Free channel resources
> + * @dchan: DMA channel
> + */
> +static void xilinx_cdma_free_chan_resources(struct dma_chan *dchan) {
> +     struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
> +     unsigned long flags;
> +
> +     spin_lock_irqsave(&chan->lock, flags);
> +     xilinx_cdma_free_desc_list(chan, &chan->done_list);
> +     xilinx_cdma_free_desc_list(chan, &chan->pending_list);
> +     spin_unlock_irqrestore(&chan->lock, flags);
> +
> +     dma_pool_destroy(chan->desc_pool);
> +     chan->desc_pool = NULL;
> +}
> +
> +/**
> + * xilinx_cdma_chan_desc_cleanup - Clean channel descriptors
> + * @chan: Driver specific cdma channel
> + */
> +static void xilinx_cdma_chan_desc_cleanup(struct xilinx_cdma_chan
> +*chan) {
> +     struct xilinx_cdma_tx_descriptor *desc, *next;
> +     unsigned long flags;
> +
> +     spin_lock_irqsave(&chan->lock, flags);
> +
> +     list_for_each_entry_safe(desc, next, &chan->done_list, node) {
> +             dma_async_tx_callback callback;
> +             void *callback_param;
> +
> +             /* 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_cdma_free_tx_descriptor(chan, desc);
> +     }
> +
> +     spin_unlock_irqrestore(&chan->lock, flags); }
> +
> +/**
> + * xilinx_cdma_tx_status - Get CDMA transaction status
> + * @dchan: DMA channel
> + * @cookie: Transaction identifier
> + * @txstate: Transaction state
> + *
> + * Return: DMA transaction status
> + */
> +static enum dma_status xilinx_tx_status(struct dma_chan *dchan,
> +                                     dma_cookie_t cookie,
> +                                     struct dma_tx_state *txstate)
> +{
> +     return dma_cookie_status(dchan, cookie, txstate); }
> +
> +/**
> + * xilinx_cdma_is_idle - Check if cdma channel is idle
> + * @chan: Driver specific cdma channel
> + *
> + * Return: 'true' if idle, 'false' if not.
> + */
> +static bool cdma_is_idle(struct xilinx_cdma_chan *chan) {
> +     return cdma_read(chan, XILINX_CDMA_STATUS_OFFSET) &
> +XILINX_CDMA_SR_IDLE; }
> +
> +/**
> + * xilinx_cdma_start_transfer - Starts cdma transfer
> + * @chan: Driver specific channel struct pointer  */ static void
> +xilinx_cdma_start_transfer(struct xilinx_cdma_chan *chan) {
> +     struct xilinx_cdma_tx_descriptor *desc;
> +     struct xilinx_cdma_tx_segment *head, *tail;
> +
> +     if (chan->err)
> +             return;
> +
> +     if (list_empty(&chan->pending_list))
> +             return;
> +
> +     if (!chan->idle)
> +             return;
> +
> +     /* If hardware is busy, cannot submit */
> +     if (chan->has_sg && !cdma_is_idle(chan)) {
> +             tail = list_entry(desc->segments.prev,
> +                               struct xilinx_cdma_tx_segment, node);
> +             cdma_write(chan, XILINX_CDMA_TDESC_OFFSET, tail-
> >phys);
> +             goto out_free_desc;
> +     }
> +
> +     desc = list_first_entry(&chan->pending_list,
> +                             struct xilinx_cdma_tx_descriptor, node);
> +
> +     if (chan->has_sg) {
> +             head = list_first_entry(&desc->segments,
> +                                     struct xilinx_cdma_tx_segment,
> node);
> +             tail = list_entry(desc->segments.prev,
> +                               struct xilinx_cdma_tx_segment, node);
> +
> +             cdma_write(chan, XILINX_CDMA_CDESC_OFFSET, head-
> >phys);
> +
> +             /* Update tail ptr register which will start the transfer */
> +             cdma_write(chan, XILINX_CDMA_TDESC_OFFSET, tail-
> >phys);
> +     } else {
> +             /* In simple mode */
> +             struct xilinx_cdma_tx_segment *segment;
> +             struct xilinx_cdma_desc_hw *hw;
> +
> +             segment = list_first_entry(&desc->segments,
> +                                        struct xilinx_cdma_tx_segment,
> +                                        node);
> +
> +             hw = &segment->hw;
> +
> +             cdma_write(chan, XILINX_CDMA_SRCADDR_OFFSET, hw-
> >src_addr);
> +             cdma_write(chan, XILINX_CDMA_DSTADDR_OFFSET, hw-
> >dest_addr);
> +
> +             /* Start the transfer */
> +             cdma_write(chan, XILINX_CDMA_BTT_OFFSET,
> +                             hw->control &
> XILINX_CDMA_MAX_TRANS_LEN);
> +     }
> +
> +out_free_desc:
> +     list_del(&desc->node);
> +     chan->idle = false;
> +     chan->active_desc = desc;
> +}
> +
> +/**
> + * xilinx_cdma_issue_pending - Issue pending transactions
> + * @dchan: DMA channel
> + */
> +static void xilinx_cdma_issue_pending(struct dma_chan *dchan) {
> +     struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
> +     unsigned long flags;
> +
> +     spin_lock_irqsave(&chan->lock, flags);
> +     xilinx_cdma_start_transfer(chan);
> +     spin_unlock_irqrestore(&chan->lock, flags); }
> +
> +/**
> + * xilinx_cdma_complete_descriptor - Mark the active descriptor as
> +complete
> + * @chan : xilinx DMA channel
> + */
> +static void xilinx_cdma_complete_descriptor(struct xilinx_cdma_chan
> +*chan) {
> +     struct xilinx_cdma_tx_descriptor *desc;
> +
> +     desc = chan->active_desc;
> +     if (!desc) {
> +             dev_dbg(chan->dev, "no running descriptors\n");
> +             return;
> +     }
> +
> +     dma_cookie_complete(&desc->async_tx);
> +     list_add_tail(&desc->node, &chan->done_list);
> +
> +     chan->active_desc = NULL;
> +}
> +
> +/**
> + * xilinx_cdma_chan_reset - Reset CDMA channel
> + * @chan: Driver specific CDMA channel
> + *
> + * Return: '0' on success and failure value on error  */ static int
> +xilinx_cdma_chan_reset(struct xilinx_cdma_chan *chan) {
> +     int loop = XILINX_CDMA_RESET_LOOP;
> +     u32 tmp;
> +
> +     cdma_ctrl_set(chan, XILINX_CDMA_CONTROL_OFFSET,
> +                     XILINX_CDMA_CR_RESET);
> +
> +     tmp = cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET) &
> +                     XILINX_CDMA_CR_RESET;
> +
> +     /* Wait for the hardware to finish reset */
> +     do {
> +             tmp = cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET) &
> +                     XILINX_CDMA_CR_RESET;
> +     } while (loop-- && tmp);
> +
> +     if (!loop) {
> +             dev_err(chan->dev, "reset timeout, cr %x, sr %x\n",
> +                     cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET),
> +                     cdma_read(chan, XILINX_CDMA_STATUS_OFFSET));
> +             return -EBUSY;
> +     }
> +
> +     /* Enable interrupts */
> +     cdma_ctrl_set(chan, XILINX_CDMA_CONTROL_OFFSET,
> +                             XILINX_CDMA_XR_IRQ_ALL_MASK);
> +
> +     /* Enable SG Mode */
> +     if (chan->has_sg)
> +             cdma_ctrl_set(chan, XILINX_CDMA_CONTROL_OFFSET,
> +                             XILINX_CDMA_CR_SGMODE);
> +     return 0;
> +}
> +
> +/**
> + * xilinx_cdma_irq_handler - CDMA Interrupt handler
> + * @irq: IRQ number
> + * @data: Pointer to the Xilinx CDMA channel structure
> + *
> + * Return: IRQ_HANDLED/IRQ_NONE
> + */
> +static irqreturn_t xilinx_cdma_irq_handler(int irq, void *data) {
> +     struct xilinx_cdma_chan *chan = data;
> +     u32 status;
> +
> +     status = cdma_read(chan, XILINX_CDMA_STATUS_OFFSET);
> +     if (!(status & XILINX_CDMA_XR_IRQ_ALL_MASK))
> +             return IRQ_NONE;
> +
> +     /* Ack the interrupts */
> +     cdma_write(chan, XILINX_CDMA_STATUS_OFFSET,
> +             XILINX_CDMA_XR_IRQ_ALL_MASK);
> +
> +     if (status & XILINX_CDMA_XR_IRQ_ERROR_MASK) {
> +             dev_err(chan->dev,
> +                     "Channel %x has errors %x, cdr %x tdr %x\n",
> +                     (u32)chan,
> +                     (u32)cdma_read(chan,
> XILINX_CDMA_STATUS_OFFSET),
> +                     (u32)cdma_read(chan,
> XILINX_CDMA_CDESC_OFFSET),
> +                     (u32)cdma_read(chan,
> XILINX_CDMA_TDESC_OFFSET));
> +             chan->err = true;
> +     }
> +
> +     /*
> +      * Device takes too long to do the transfer when user requires
> +      * responsiveness
> +      */
> +     if (status & XILINX_CDMA_XR_IRQ_DELAY_MASK)
> +             dev_dbg(chan->dev, "Inter-packet latency too long\n");
> +
> +     if (status & XILINX_CDMA_XR_IRQ_IOC_MASK) {
> +             spin_lock(&chan->lock);
> +             xilinx_cdma_complete_descriptor(chan);
> +             chan->idle = true;
> +             xilinx_cdma_start_transfer(chan);
> +             spin_unlock(&chan->lock);
> +     }
> +
> +     tasklet_schedule(&chan->tasklet);
> +     return IRQ_HANDLED;
> +}
> +
> +/**
> + * xilinx_cdma_do_tasklet - Schedule completion tasklet
> + * @data: Pointer to the Xilinx cdma channel structure  */ static void
> +xilinx_cdma_do_tasklet(unsigned long data) {
> +     struct xilinx_cdma_chan *chan = (struct xilinx_cdma_chan *)data;
> +
> +     xilinx_cdma_chan_desc_cleanup(chan);
> +}
> +
> +/**
> + * xilinx_cdma_tx_submit - Submit DMA transaction
> + * @tx: Async transaction descriptor
> + *
> + * Return: cookie value on success and failure value on error  */
> +static dma_cookie_t xilinx_cdma_tx_submit(struct
> +dma_async_tx_descriptor *tx) {
> +     struct xilinx_cdma_chan *chan = to_xilinx_chan(tx->chan);
> +     struct xilinx_cdma_tx_descriptor *desc =
> to_cdma_tx_descriptor(tx);
> +     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_cdma_chan_reset(chan);
> +             if (err < 0)
> +                     return err;
> +     }
> +
> +     spin_lock_irqsave(&chan->lock, flags);
> +
> +     cookie = dma_cookie_assign(tx);
> +
> +     /* Append the transaction to the pending transactions queue. */
> +     list_add_tail(&desc->node, &chan->pending_list);
> +
> +     spin_unlock_irqrestore(&chan->lock, flags);
> +
> +     return cookie;
> +}
> +
> +/**
> + * xilinx_cdma_prep_memcpy - prepare descriptors for a memcpy
> +transaction
> + * @dchan: DMA channel
> + * @dma_dst: destination address
> + * @dma_src: source address
> + * @len: transfer length
> + * @flags: transfer ack flags
> + *
> + * Return: Async transaction descriptor on success and NULL on failure
> +*/ static struct dma_async_tx_descriptor *
> +xilinx_cdma_prep_memcpy(struct dma_chan *dchan, dma_addr_t
> dma_dst,
> +                     dma_addr_t dma_src, size_t len, unsigned long flags)
> {
> +     struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
> +     struct xilinx_cdma_desc_hw *hw;
> +     struct xilinx_cdma_tx_descriptor *desc;
> +     struct xilinx_cdma_tx_segment *segment, *prev;
> +
> +     if (!len || len > XILINX_CDMA_MAX_TRANS_LEN)
> +             return NULL;
> +
> +     desc = xilinx_cdma_alloc_tx_descriptor(chan);
> +     if (!desc)
> +             return NULL;
> +
> +     dma_async_tx_descriptor_init(&desc->async_tx, &chan->common);
> +     desc->async_tx.tx_submit = xilinx_cdma_tx_submit;
> +     async_tx_ack(&desc->async_tx);
> +
> +     /* Allocate the link descriptor from DMA pool */
> +     segment = xilinx_cdma_alloc_tx_segment(chan);
> +     if (!segment)
> +             goto error;
> +
> +     hw = &segment->hw;
> +     hw->control = len;
> +     hw->src_addr = dma_src;
> +     hw->dest_addr = dma_dst;
> +
> +     /* Fill the previous next descriptor with current */
> +     prev = list_last_entry(&desc->segments,
> +                             struct xilinx_cdma_tx_segment, node);
> +     prev->hw.next_desc = segment->phys;
> +
> +     /* Insert the segment into the descriptor segments list. */
> +     list_add_tail(&segment->node, &desc->segments);
> +
> +     prev = segment;
> +
> +     /* Link the last hardware descriptor with the first. */
> +     segment = list_first_entry(&desc->segments,
> +                             struct xilinx_cdma_tx_segment, node);
> +     prev->hw.next_desc = segment->phys;
> +
> +     return &desc->async_tx;
> +
> +error:
> +     xilinx_cdma_free_tx_descriptor(chan, desc);
> +     return NULL;
> +}
> +
> +/**
> + * xilinx_cdma_terminate_all - Free the descriptors
> + * @dchan: DMA Channel pointer
> + *
> + * Return: '0' always
> + */
> +static int xilinx_cdma_terminate_all(struct dma_chan *dchan) {
> +     struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
> +     unsigned long flags;
> +
> +     spin_lock_irqsave(&chan->lock, flags);
> +
> +     /* Reset the channel */
> +     xilinx_cdma_chan_reset(chan);
> +
> +     /* Remove and free all of the descriptors in the lists */
> +     xilinx_cdma_free_desc_list(chan, &chan->pending_list);
> +     xilinx_cdma_free_desc_list(chan, &chan->done_list);
> +
> +     spin_unlock_irqrestore(&chan->lock, flags);
> +
> +     return 0;
> +}
> +
> +/**
> + * xilinx_cdma_channel_set_config - Configure cdma channel
> + * @dchan: DMA channel
> + * @cfg: cdma device configuration pointer
> + *
> + * Return: '0' on success and failure value on error  */ int
> +xilinx_cdma_channel_set_config(struct dma_chan *dchan,
> +                                     struct xilinx_cdma_config *cfg)
> +{
> +     struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
> +     u32 reg = cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET);
> +
> +     if (!cdma_is_idle(chan))
> +             return -EBUSY;
> +
> +     if (cfg->reset)
> +             return xilinx_cdma_chan_reset(chan);
> +
> +     if (cfg->coalesc <= XILINX_CDMA_COALESCE_MAX) {
> +             reg &= ~XILINX_CDMA_XR_COALESCE_MASK;
> +             reg |= cfg->coalesc << XILINX_CDMA_COALESCE_SHIFT;
> +     }
> +
> +     if (cfg->delay <= XILINX_CDMA_DELAY_MAX) {
> +             reg &= ~XILINX_CDMA_XR_DELAY_MASK;
> +             reg |= cfg->delay << XILINX_CDMA_DELAY_SHIFT;
> +     }
> +
> +     cdma_write(chan, XILINX_CDMA_CONTROL_OFFSET, reg);
> +
> +     return 0;
> +}
> +EXPORT_SYMBOL(xilinx_cdma_channel_set_config);
> +
> +/*
> +-----------------------------------------------------------------------
> +------
> + * Probe and remove
> + */
> +
> +/**
> + * xilinx_cdma_free_channel - Channel remove function
> + * @chan: Driver specific cdma channel
> + */
> +static void xilinx_cdma_free_channel(struct xilinx_cdma_chan *chan) {
> +     /* Disable Interrupts */
> +     cdma_ctrl_clr(chan, XILINX_CDMA_CONTROL_OFFSET,
> +             XILINX_CDMA_XR_IRQ_ALL_MASK);
> +
> +     if (chan->irq > 0)
> +             free_irq(chan->irq, chan);
> +
> +     tasklet_kill(&chan->tasklet);
> +
> +     list_del(&chan->common.device_node);
> +}
> +
> +/**
> + * xilinx_cdma_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_cdma_chan_probe(struct xilinx_cdma_device *xdev,
> +                                     struct device_node *node)
> +{
> +     struct xilinx_cdma_chan *chan;
> +     bool has_dre;
> +     u32 value, width;
> +     int err;
> +
> +     /* Alloc channel */
> +     chan = devm_kzalloc(xdev->dev, sizeof(*chan), GFP_NOWAIT);
> +     if (!chan)
> +             return -ENOMEM;
> +
> +     chan->dev = xdev->dev;
> +     chan->has_sg = xdev->has_sg;
> +     chan->xdev = xdev;
> +
> +     spin_lock_init(&chan->lock);
> +     INIT_LIST_HEAD(&chan->pending_list);
> +     INIT_LIST_HEAD(&chan->done_list);
> +
> +     /* Retrieve the channel properties from the device tree */
> +     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);
> +
> +     /* Request the interrupt */
> +     chan->irq = irq_of_parse_and_map(node, 0);
> +     err = request_irq(chan->irq, xilinx_cdma_irq_handler, IRQF_SHARED,
> +                             "xilinx-cdma-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_cdma_do_tasklet,
> +                             (unsigned long)chan);
> +
> +     /*
> +      * Initialize the DMA channel and add it to the DMA engine channels
> +      * list.
> +      */
> +     chan->common.device = &xdev->common;
> +
> +     list_add_tail(&chan->common.device_node, &xdev-
> >common.channels);
> +     xdev->chan = chan;
> +
> +     /* Initialize the channel */
> +     err = xilinx_cdma_chan_reset(chan);
> +     if (err) {
> +             dev_err(xdev->dev, "Reset channel failed\n");
> +             return err;
> +     }
> +
> +     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_cdma_device *xdev = ofdma->of_dma_data;
> +
> +     return dma_get_slave_channel(&xdev->chan->common);
> +}
> +
> +/**
> + * xilinx_cdma_probe - Driver probe function
> + * @pdev: Pointer to the platform_device structure
> + *
> + * Return: '0' on success and failure value on error  */ static int
> +xilinx_cdma_probe(struct platform_device *pdev) {
> +     struct xilinx_cdma_device *xdev;
> +     struct device_node *child, *node;
> +     struct resource *res;
> +     int 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");
> +
> +     dma_cap_set(DMA_MEMCPY, xdev->common.cap_mask);
> +     xdev->common.device_prep_dma_memcpy =
> xilinx_cdma_prep_memcpy;
> +     xdev->common.device_terminate_all = xilinx_cdma_terminate_all;
> +     xdev->common.device_issue_pending =
> xilinx_cdma_issue_pending;
> +     xdev->common.device_alloc_chan_resources =
> +                     xilinx_cdma_alloc_chan_resources;
> +     xdev->common.device_free_chan_resources =
> +                     xilinx_cdma_free_chan_resources;
> +     xdev->common.device_tx_status = xilinx_tx_status;
> +     xdev->common.dev = &pdev->dev;
> +
> +     platform_set_drvdata(pdev, xdev);
> +
> +     child = of_get_next_child(node, NULL);
> +     if (!child) {
> +             dev_err(&pdev->dev, "No channel found\n");
> +             return PTR_ERR(child);
> +     }
> +
> +     ret = xilinx_cdma_chan_probe(xdev, child);
> +     if (ret) {
> +             dev_err(&pdev->dev, "Probing channel 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 CDMA Engine driver Probed!!\n");
> +
> +     return 0;
> +
> +free_chan_resources:
> +     xilinx_cdma_free_channel(xdev->chan);
> +
> +     return ret;
> +}
> +
> +/**
> + * xilinx_cdma_remove - Driver remove function
> + * @pdev: Pointer to the platform_device structure
> + *
> + * Return: Always '0'
> + */
> +static int xilinx_cdma_remove(struct platform_device *pdev) {
> +      struct xilinx_cdma_device *xdev = platform_get_drvdata(pdev);
> +
> +     of_dma_controller_free(pdev->dev.of_node);
> +     dma_async_device_unregister(&xdev->common);
> +
> +     xilinx_cdma_free_channel(xdev->chan);
> +
> +     return 0;
> +}
> +
> +static const struct of_device_id xilinx_cdma_of_match[] = {
> +     { .compatible = "xlnx,axi-cdma-1.00.a", },
> +     {}
> +};
> +MODULE_DEVICE_TABLE(of, xilinx_cdma_of_match);
> +
> +static struct platform_driver xilinx_cdma_driver = {
> +     .driver = {
> +             .name = "xilinx-cdma",
> +             .owner = THIS_MODULE,
> +             .of_match_table = xilinx_cdma_of_match,
> +     },
> +     .probe = xilinx_cdma_probe,
> +     .remove = xilinx_cdma_remove,
> +};
> +
> +module_platform_driver(xilinx_cdma_driver);
> +
> +MODULE_AUTHOR("Xilinx, Inc.");
> +MODULE_DESCRIPTION("Xilinx CDMA driver"); MODULE_LICENSE("GPL
> v2");
> diff --git a/include/linux/dma/xilinx_dma.h
> b/include/linux/dma/xilinx_dma.h index 34b98f2..fb74ff7 100644
> --- a/include/linux/dma/xilinx_dma.h
> +++ b/include/linux/dma/xilinx_dma.h
> @@ -41,7 +41,20 @@ struct xilinx_vdma_config {
>       int ext_fsync;
>  };
>
> +/**
> + * struct xilinx_cdma_config - CDMA Configuration structure
> + * @coalesc: Interrupt coalescing threshold
> + * @delay: Delay counter
> + * @reset: Reset Channel
> + */
> +struct xilinx_cdma_config {
> +     int coalesc;
> +     int delay;
> +     int reset;
> +};
> +
>  int xilinx_vdma_channel_set_config(struct dma_chan *dchan,
>                                       struct xilinx_vdma_config *cfg);
> -
> +int xilinx_cdma_channel_set_config(struct dma_chan *dchan,
> +                                     struct xilinx_cdma_config *cfg);
>  #endif
> --
> 2.1.2


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