dmaengine: tegra20: Fix runtime PM imbalance on error

[mirror_ubuntu-hirsute-kernel.git] / drivers / dma / tegra20-apb-dma.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * DMA driver for Nvidia's Tegra20 APB DMA controller.
 *
 * Copyright (c) 2012-2013, NVIDIA CORPORATION.  All rights reserved.
 */

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/slab.h>
#include <linux/wait.h>

#include "dmaengine.h"

#define CREATE_TRACE_POINTS
#include <trace/events/tegra_apb_dma.h>

#define TEGRA_APBDMA_GENERAL                    0x0
#define TEGRA_APBDMA_GENERAL_ENABLE             BIT(31)

#define TEGRA_APBDMA_CONTROL                    0x010
#define TEGRA_APBDMA_IRQ_MASK                   0x01c
#define TEGRA_APBDMA_IRQ_MASK_SET               0x020

/* CSR register */
#define TEGRA_APBDMA_CHAN_CSR                   0x00
#define TEGRA_APBDMA_CSR_ENB                    BIT(31)
#define TEGRA_APBDMA_CSR_IE_EOC                 BIT(30)
#define TEGRA_APBDMA_CSR_HOLD                   BIT(29)
#define TEGRA_APBDMA_CSR_DIR                    BIT(28)
#define TEGRA_APBDMA_CSR_ONCE                   BIT(27)
#define TEGRA_APBDMA_CSR_FLOW                   BIT(21)
#define TEGRA_APBDMA_CSR_REQ_SEL_SHIFT          16
#define TEGRA_APBDMA_CSR_REQ_SEL_MASK           0x1F
#define TEGRA_APBDMA_CSR_WCOUNT_MASK            0xFFFC

/* STATUS register */
#define TEGRA_APBDMA_CHAN_STATUS                0x004
#define TEGRA_APBDMA_STATUS_BUSY                BIT(31)
#define TEGRA_APBDMA_STATUS_ISE_EOC             BIT(30)
#define TEGRA_APBDMA_STATUS_HALT                BIT(29)
#define TEGRA_APBDMA_STATUS_PING_PONG           BIT(28)
#define TEGRA_APBDMA_STATUS_COUNT_SHIFT         2
#define TEGRA_APBDMA_STATUS_COUNT_MASK          0xFFFC

#define TEGRA_APBDMA_CHAN_CSRE                  0x00C
#define TEGRA_APBDMA_CHAN_CSRE_PAUSE            BIT(31)

/* AHB memory address */
#define TEGRA_APBDMA_CHAN_AHBPTR                0x010

/* AHB sequence register */
#define TEGRA_APBDMA_CHAN_AHBSEQ                0x14
#define TEGRA_APBDMA_AHBSEQ_INTR_ENB            BIT(31)
#define TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_8         (0 << 28)
#define TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_16        (1 << 28)
#define TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_32        (2 << 28)
#define TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_64        (3 << 28)
#define TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_128       (4 << 28)
#define TEGRA_APBDMA_AHBSEQ_DATA_SWAP           BIT(27)
#define TEGRA_APBDMA_AHBSEQ_BURST_1             (4 << 24)
#define TEGRA_APBDMA_AHBSEQ_BURST_4             (5 << 24)
#define TEGRA_APBDMA_AHBSEQ_BURST_8             (6 << 24)
#define TEGRA_APBDMA_AHBSEQ_DBL_BUF             BIT(19)
#define TEGRA_APBDMA_AHBSEQ_WRAP_SHIFT          16
#define TEGRA_APBDMA_AHBSEQ_WRAP_NONE           0

/* APB address */
#define TEGRA_APBDMA_CHAN_APBPTR                0x018

/* APB sequence register */
#define TEGRA_APBDMA_CHAN_APBSEQ                0x01c
#define TEGRA_APBDMA_APBSEQ_BUS_WIDTH_8         (0 << 28)
#define TEGRA_APBDMA_APBSEQ_BUS_WIDTH_16        (1 << 28)
#define TEGRA_APBDMA_APBSEQ_BUS_WIDTH_32        (2 << 28)
#define TEGRA_APBDMA_APBSEQ_BUS_WIDTH_64        (3 << 28)
#define TEGRA_APBDMA_APBSEQ_BUS_WIDTH_128       (4 << 28)
#define TEGRA_APBDMA_APBSEQ_DATA_SWAP           BIT(27)
#define TEGRA_APBDMA_APBSEQ_WRAP_WORD_1         (1 << 16)

/* Tegra148 specific registers */
#define TEGRA_APBDMA_CHAN_WCOUNT                0x20

#define TEGRA_APBDMA_CHAN_WORD_TRANSFER         0x24

/*
 * If any burst is in flight and DMA paused then this is the time to complete
 * on-flight burst and update DMA status register.
 */
#define TEGRA_APBDMA_BURST_COMPLETE_TIME        20

/* Channel base address offset from APBDMA base address */
#define TEGRA_APBDMA_CHANNEL_BASE_ADD_OFFSET    0x1000

#define TEGRA_APBDMA_SLAVE_ID_INVALID   (TEGRA_APBDMA_CSR_REQ_SEL_MASK + 1)

struct tegra_dma;

/*
 * tegra_dma_chip_data Tegra chip specific DMA data
 * @nr_channels: Number of channels available in the controller.
 * @channel_reg_size: Channel register size/stride.
 * @max_dma_count: Maximum DMA transfer count supported by DMA controller.
 * @support_channel_pause: Support channel wise pause of dma.
 * @support_separate_wcount_reg: Support separate word count register.
 */
struct tegra_dma_chip_data {
        unsigned int nr_channels;
        unsigned int channel_reg_size;
        unsigned int max_dma_count;
        bool support_channel_pause;
        bool support_separate_wcount_reg;
};

/* DMA channel registers */
struct tegra_dma_channel_regs {
        u32 csr;
        u32 ahb_ptr;
        u32 apb_ptr;
        u32 ahb_seq;
        u32 apb_seq;
        u32 wcount;
};

/*
 * tegra_dma_sg_req: DMA request details to configure hardware. This
 * contains the details for one transfer to configure DMA hw.
 * The client's request for data transfer can be broken into multiple
 * sub-transfer as per requester details and hw support.
 * This sub transfer get added in the list of transfer and point to Tegra
 * DMA descriptor which manages the transfer details.
 */
struct tegra_dma_sg_req {
        struct tegra_dma_channel_regs   ch_regs;
        unsigned int                    req_len;
        bool                            configured;
        bool                            last_sg;
        struct list_head                node;
        struct tegra_dma_desc           *dma_desc;
        unsigned int                    words_xferred;
};

/*
 * tegra_dma_desc: Tegra DMA descriptors which manages the client requests.
 * This descriptor keep track of transfer status, callbacks and request
 * counts etc.
 */
struct tegra_dma_desc {
        struct dma_async_tx_descriptor  txd;
        unsigned int                    bytes_requested;
        unsigned int                    bytes_transferred;
        enum dma_status                 dma_status;
        struct list_head                node;
        struct list_head                tx_list;
        struct list_head                cb_node;
        unsigned int                    cb_count;
};

struct tegra_dma_channel;

typedef void (*dma_isr_handler)(struct tegra_dma_channel *tdc,
                                bool to_terminate);

/* tegra_dma_channel: Channel specific information */
struct tegra_dma_channel {
        struct dma_chan         dma_chan;
        char                    name[12];
        bool                    config_init;
        unsigned int            id;
        void __iomem            *chan_addr;
        spinlock_t              lock;
        bool                    busy;
        struct tegra_dma        *tdma;
        bool                    cyclic;

        /* Different lists for managing the requests */
        struct list_head        free_sg_req;
        struct list_head        pending_sg_req;
        struct list_head        free_dma_desc;
        struct list_head        cb_desc;

        /* ISR handler and tasklet for bottom half of isr handling */
        dma_isr_handler         isr_handler;
        struct tasklet_struct   tasklet;

        /* Channel-slave specific configuration */
        unsigned int slave_id;
        struct dma_slave_config dma_sconfig;
        struct tegra_dma_channel_regs channel_reg;

        struct wait_queue_head wq;
};

/* tegra_dma: Tegra DMA specific information */
struct tegra_dma {
        struct dma_device               dma_dev;
        struct device                   *dev;
        struct clk                      *dma_clk;
        struct reset_control            *rst;
        spinlock_t                      global_lock;
        void __iomem                    *base_addr;
        const struct tegra_dma_chip_data *chip_data;

        /*
         * Counter for managing global pausing of the DMA controller.
         * Only applicable for devices that don't support individual
         * channel pausing.
         */
        u32                             global_pause_count;

        /* Last member of the structure */
        struct tegra_dma_channel channels[];
};

static inline void tdma_write(struct tegra_dma *tdma, u32 reg, u32 val)
{
        writel(val, tdma->base_addr + reg);
}

static inline u32 tdma_read(struct tegra_dma *tdma, u32 reg)
{
        return readl(tdma->base_addr + reg);
}

static inline void tdc_write(struct tegra_dma_channel *tdc,
                             u32 reg, u32 val)
{
        writel(val, tdc->chan_addr + reg);
}

static inline u32 tdc_read(struct tegra_dma_channel *tdc, u32 reg)
{
        return readl(tdc->chan_addr + reg);
}

static inline struct tegra_dma_channel *to_tegra_dma_chan(struct dma_chan *dc)
{
        return container_of(dc, struct tegra_dma_channel, dma_chan);
}

static inline struct tegra_dma_desc *
txd_to_tegra_dma_desc(struct dma_async_tx_descriptor *td)
{
        return container_of(td, struct tegra_dma_desc, txd);
}

static inline struct device *tdc2dev(struct tegra_dma_channel *tdc)
{
        return &tdc->dma_chan.dev->device;
}

static dma_cookie_t tegra_dma_tx_submit(struct dma_async_tx_descriptor *tx);

/* Get DMA desc from free list, if not there then allocate it.  */
static struct tegra_dma_desc *tegra_dma_desc_get(struct tegra_dma_channel *tdc)
{
        struct tegra_dma_desc *dma_desc;
        unsigned long flags;

        spin_lock_irqsave(&tdc->lock, flags);

        /* Do not allocate if desc are waiting for ack */
        list_for_each_entry(dma_desc, &tdc->free_dma_desc, node) {
                if (async_tx_test_ack(&dma_desc->txd) && !dma_desc->cb_count) {
                        list_del(&dma_desc->node);
                        spin_unlock_irqrestore(&tdc->lock, flags);
                        dma_desc->txd.flags = 0;
                        return dma_desc;
                }
        }

        spin_unlock_irqrestore(&tdc->lock, flags);

        /* Allocate DMA desc */
        dma_desc = kzalloc(sizeof(*dma_desc), GFP_NOWAIT);
        if (!dma_desc)
                return NULL;

        dma_async_tx_descriptor_init(&dma_desc->txd, &tdc->dma_chan);
        dma_desc->txd.tx_submit = tegra_dma_tx_submit;
        dma_desc->txd.flags = 0;

        return dma_desc;
}

static void tegra_dma_desc_put(struct tegra_dma_channel *tdc,
                               struct tegra_dma_desc *dma_desc)
{
        unsigned long flags;

        spin_lock_irqsave(&tdc->lock, flags);
        if (!list_empty(&dma_desc->tx_list))
                list_splice_init(&dma_desc->tx_list, &tdc->free_sg_req);
        list_add_tail(&dma_desc->node, &tdc->free_dma_desc);
        spin_unlock_irqrestore(&tdc->lock, flags);
}

static struct tegra_dma_sg_req *
tegra_dma_sg_req_get(struct tegra_dma_channel *tdc)
{
        struct tegra_dma_sg_req *sg_req;
        unsigned long flags;

        spin_lock_irqsave(&tdc->lock, flags);
        if (!list_empty(&tdc->free_sg_req)) {
                sg_req = list_first_entry(&tdc->free_sg_req, typeof(*sg_req),
                                          node);
                list_del(&sg_req->node);
                spin_unlock_irqrestore(&tdc->lock, flags);
                return sg_req;
        }
        spin_unlock_irqrestore(&tdc->lock, flags);

        sg_req = kzalloc(sizeof(*sg_req), GFP_NOWAIT);

        return sg_req;
}

static int tegra_dma_slave_config(struct dma_chan *dc,
                                  struct dma_slave_config *sconfig)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);

        if (!list_empty(&tdc->pending_sg_req)) {
                dev_err(tdc2dev(tdc), "Configuration not allowed\n");
                return -EBUSY;
        }

        memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig));
        if (tdc->slave_id == TEGRA_APBDMA_SLAVE_ID_INVALID &&
            sconfig->device_fc) {
                if (sconfig->slave_id > TEGRA_APBDMA_CSR_REQ_SEL_MASK)
                        return -EINVAL;
                tdc->slave_id = sconfig->slave_id;
        }
        tdc->config_init = true;

        return 0;
}

static void tegra_dma_global_pause(struct tegra_dma_channel *tdc,
                                   bool wait_for_burst_complete)
{
        struct tegra_dma *tdma = tdc->tdma;

        spin_lock(&tdma->global_lock);

        if (tdc->tdma->global_pause_count == 0) {
                tdma_write(tdma, TEGRA_APBDMA_GENERAL, 0);
                if (wait_for_burst_complete)
                        udelay(TEGRA_APBDMA_BURST_COMPLETE_TIME);
        }

        tdc->tdma->global_pause_count++;

        spin_unlock(&tdma->global_lock);
}

static void tegra_dma_global_resume(struct tegra_dma_channel *tdc)
{
        struct tegra_dma *tdma = tdc->tdma;

        spin_lock(&tdma->global_lock);

        if (WARN_ON(tdc->tdma->global_pause_count == 0))
                goto out;

        if (--tdc->tdma->global_pause_count == 0)
                tdma_write(tdma, TEGRA_APBDMA_GENERAL,
                           TEGRA_APBDMA_GENERAL_ENABLE);

out:
        spin_unlock(&tdma->global_lock);
}

static void tegra_dma_pause(struct tegra_dma_channel *tdc,
                            bool wait_for_burst_complete)
{
        struct tegra_dma *tdma = tdc->tdma;

        if (tdma->chip_data->support_channel_pause) {
                tdc_write(tdc, TEGRA_APBDMA_CHAN_CSRE,
                          TEGRA_APBDMA_CHAN_CSRE_PAUSE);
                if (wait_for_burst_complete)
                        udelay(TEGRA_APBDMA_BURST_COMPLETE_TIME);
        } else {
                tegra_dma_global_pause(tdc, wait_for_burst_complete);
        }
}

static void tegra_dma_resume(struct tegra_dma_channel *tdc)
{
        struct tegra_dma *tdma = tdc->tdma;

        if (tdma->chip_data->support_channel_pause)
                tdc_write(tdc, TEGRA_APBDMA_CHAN_CSRE, 0);
        else
                tegra_dma_global_resume(tdc);
}

static void tegra_dma_stop(struct tegra_dma_channel *tdc)
{
        u32 csr, status;

        /* Disable interrupts */
        csr = tdc_read(tdc, TEGRA_APBDMA_CHAN_CSR);
        csr &= ~TEGRA_APBDMA_CSR_IE_EOC;
        tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR, csr);

        /* Disable DMA */
        csr &= ~TEGRA_APBDMA_CSR_ENB;
        tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR, csr);

        /* Clear interrupt status if it is there */
        status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);
        if (status & TEGRA_APBDMA_STATUS_ISE_EOC) {
                dev_dbg(tdc2dev(tdc), "%s():clearing interrupt\n", __func__);
                tdc_write(tdc, TEGRA_APBDMA_CHAN_STATUS, status);
        }
        tdc->busy = false;
}

static void tegra_dma_start(struct tegra_dma_channel *tdc,
                            struct tegra_dma_sg_req *sg_req)
{
        struct tegra_dma_channel_regs *ch_regs = &sg_req->ch_regs;

        tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR, ch_regs->csr);
        tdc_write(tdc, TEGRA_APBDMA_CHAN_APBSEQ, ch_regs->apb_seq);
        tdc_write(tdc, TEGRA_APBDMA_CHAN_APBPTR, ch_regs->apb_ptr);
        tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBSEQ, ch_regs->ahb_seq);
        tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBPTR, ch_regs->ahb_ptr);
        if (tdc->tdma->chip_data->support_separate_wcount_reg)
                tdc_write(tdc, TEGRA_APBDMA_CHAN_WCOUNT, ch_regs->wcount);

        /* Start DMA */
        tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR,
                  ch_regs->csr | TEGRA_APBDMA_CSR_ENB);
}

static void tegra_dma_configure_for_next(struct tegra_dma_channel *tdc,
                                         struct tegra_dma_sg_req *nsg_req)
{
        unsigned long status;

        /*
         * The DMA controller reloads the new configuration for next transfer
         * after last burst of current transfer completes.
         * If there is no IEC status then this makes sure that last burst
         * has not be completed. There may be case that last burst is on
         * flight and so it can complete but because DMA is paused, it
         * will not generates interrupt as well as not reload the new
         * configuration.
         * If there is already IEC status then interrupt handler need to
         * load new configuration.
         */
        tegra_dma_pause(tdc, false);
        status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);

        /*
         * If interrupt is pending then do nothing as the ISR will handle
         * the programing for new request.
         */
        if (status & TEGRA_APBDMA_STATUS_ISE_EOC) {
                dev_err(tdc2dev(tdc),
                        "Skipping new configuration as interrupt is pending\n");
                tegra_dma_resume(tdc);
                return;
        }

        /* Safe to program new configuration */
        tdc_write(tdc, TEGRA_APBDMA_CHAN_APBPTR, nsg_req->ch_regs.apb_ptr);
        tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBPTR, nsg_req->ch_regs.ahb_ptr);
        if (tdc->tdma->chip_data->support_separate_wcount_reg)
                tdc_write(tdc, TEGRA_APBDMA_CHAN_WCOUNT,
                          nsg_req->ch_regs.wcount);
        tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR,
                  nsg_req->ch_regs.csr | TEGRA_APBDMA_CSR_ENB);
        nsg_req->configured = true;
        nsg_req->words_xferred = 0;

        tegra_dma_resume(tdc);
}

static void tdc_start_head_req(struct tegra_dma_channel *tdc)
{
        struct tegra_dma_sg_req *sg_req;

        sg_req = list_first_entry(&tdc->pending_sg_req, typeof(*sg_req), node);
        tegra_dma_start(tdc, sg_req);
        sg_req->configured = true;
        sg_req->words_xferred = 0;
        tdc->busy = true;
}

static void tdc_configure_next_head_desc(struct tegra_dma_channel *tdc)
{
        struct tegra_dma_sg_req *hsgreq, *hnsgreq;

        hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
        if (!list_is_last(&hsgreq->node, &tdc->pending_sg_req)) {
                hnsgreq = list_first_entry(&hsgreq->node, typeof(*hnsgreq),
                                           node);
                tegra_dma_configure_for_next(tdc, hnsgreq);
        }
}

static inline unsigned int
get_current_xferred_count(struct tegra_dma_channel *tdc,
                          struct tegra_dma_sg_req *sg_req,
                          unsigned long status)
{
        return sg_req->req_len - (status & TEGRA_APBDMA_STATUS_COUNT_MASK) - 4;
}

static void tegra_dma_abort_all(struct tegra_dma_channel *tdc)
{
        struct tegra_dma_desc *dma_desc;
        struct tegra_dma_sg_req *sgreq;

        while (!list_empty(&tdc->pending_sg_req)) {
                sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq),
                                         node);
                list_move_tail(&sgreq->node, &tdc->free_sg_req);
                if (sgreq->last_sg) {
                        dma_desc = sgreq->dma_desc;
                        dma_desc->dma_status = DMA_ERROR;
                        list_add_tail(&dma_desc->node, &tdc->free_dma_desc);

                        /* Add in cb list if it is not there. */
                        if (!dma_desc->cb_count)
                                list_add_tail(&dma_desc->cb_node,
                                              &tdc->cb_desc);
                        dma_desc->cb_count++;
                }
        }
        tdc->isr_handler = NULL;
}

static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
                                           bool to_terminate)
{
        struct tegra_dma_sg_req *hsgreq;

        /*
         * Check that head req on list should be in flight.
         * If it is not in flight then abort transfer as
         * looping of transfer can not continue.
         */
        hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
        if (!hsgreq->configured) {
                tegra_dma_stop(tdc);
                pm_runtime_put(tdc->tdma->dev);
                dev_err(tdc2dev(tdc), "DMA transfer underflow, aborting DMA\n");
                tegra_dma_abort_all(tdc);
                return false;
        }

        /* Configure next request */
        if (!to_terminate)
                tdc_configure_next_head_desc(tdc);

        return true;
}

static void handle_once_dma_done(struct tegra_dma_channel *tdc,
                                 bool to_terminate)
{
        struct tegra_dma_desc *dma_desc;
        struct tegra_dma_sg_req *sgreq;

        tdc->busy = false;
        sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq), node);
        dma_desc = sgreq->dma_desc;
        dma_desc->bytes_transferred += sgreq->req_len;

        list_del(&sgreq->node);
        if (sgreq->last_sg) {
                dma_desc->dma_status = DMA_COMPLETE;
                dma_cookie_complete(&dma_desc->txd);
                if (!dma_desc->cb_count)
                        list_add_tail(&dma_desc->cb_node, &tdc->cb_desc);
                dma_desc->cb_count++;
                list_add_tail(&dma_desc->node, &tdc->free_dma_desc);
        }
        list_add_tail(&sgreq->node, &tdc->free_sg_req);

        /* Do not start DMA if it is going to be terminate */
        if (to_terminate)
                return;

        if (list_empty(&tdc->pending_sg_req)) {
                pm_runtime_put(tdc->tdma->dev);
                return;
        }

        tdc_start_head_req(tdc);
}

static void handle_cont_sngl_cycle_dma_done(struct tegra_dma_channel *tdc,
                                            bool to_terminate)
{
        struct tegra_dma_desc *dma_desc;
        struct tegra_dma_sg_req *sgreq;
        bool st;

        sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq), node);
        dma_desc = sgreq->dma_desc;
        /* if we dma for long enough the transfer count will wrap */
        dma_desc->bytes_transferred =
                (dma_desc->bytes_transferred + sgreq->req_len) %
                dma_desc->bytes_requested;

        /* Callback need to be call */
        if (!dma_desc->cb_count)
                list_add_tail(&dma_desc->cb_node, &tdc->cb_desc);
        dma_desc->cb_count++;

        sgreq->words_xferred = 0;

        /* If not last req then put at end of pending list */
        if (!list_is_last(&sgreq->node, &tdc->pending_sg_req)) {
                list_move_tail(&sgreq->node, &tdc->pending_sg_req);
                sgreq->configured = false;
                st = handle_continuous_head_request(tdc, to_terminate);
                if (!st)
                        dma_desc->dma_status = DMA_ERROR;
        }
}

static void tegra_dma_tasklet(struct tasklet_struct *t)
{
        struct tegra_dma_channel *tdc = from_tasklet(tdc, t, tasklet);
        struct dmaengine_desc_callback cb;
        struct tegra_dma_desc *dma_desc;
        unsigned int cb_count;
        unsigned long flags;

        spin_lock_irqsave(&tdc->lock, flags);
        while (!list_empty(&tdc->cb_desc)) {
                dma_desc = list_first_entry(&tdc->cb_desc, typeof(*dma_desc),
                                            cb_node);
                list_del(&dma_desc->cb_node);
                dmaengine_desc_get_callback(&dma_desc->txd, &cb);
                cb_count = dma_desc->cb_count;
                dma_desc->cb_count = 0;
                trace_tegra_dma_complete_cb(&tdc->dma_chan, cb_count,
                                            cb.callback);
                spin_unlock_irqrestore(&tdc->lock, flags);
                while (cb_count--)
                        dmaengine_desc_callback_invoke(&cb, NULL);
                spin_lock_irqsave(&tdc->lock, flags);
        }
        spin_unlock_irqrestore(&tdc->lock, flags);
}

static irqreturn_t tegra_dma_isr(int irq, void *dev_id)
{
        struct tegra_dma_channel *tdc = dev_id;
        u32 status;

        spin_lock(&tdc->lock);

        trace_tegra_dma_isr(&tdc->dma_chan, irq);
        status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);
        if (status & TEGRA_APBDMA_STATUS_ISE_EOC) {
                tdc_write(tdc, TEGRA_APBDMA_CHAN_STATUS, status);
                tdc->isr_handler(tdc, false);
                tasklet_schedule(&tdc->tasklet);
                wake_up_all(&tdc->wq);
                spin_unlock(&tdc->lock);
                return IRQ_HANDLED;
        }

        spin_unlock(&tdc->lock);
        dev_info(tdc2dev(tdc), "Interrupt already served status 0x%08x\n",
                 status);

        return IRQ_NONE;
}

static dma_cookie_t tegra_dma_tx_submit(struct dma_async_tx_descriptor *txd)
{
        struct tegra_dma_desc *dma_desc = txd_to_tegra_dma_desc(txd);
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(txd->chan);
        unsigned long flags;
        dma_cookie_t cookie;

        spin_lock_irqsave(&tdc->lock, flags);
        dma_desc->dma_status = DMA_IN_PROGRESS;
        cookie = dma_cookie_assign(&dma_desc->txd);
        list_splice_tail_init(&dma_desc->tx_list, &tdc->pending_sg_req);
        spin_unlock_irqrestore(&tdc->lock, flags);

        return cookie;
}

static void tegra_dma_issue_pending(struct dma_chan *dc)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
        unsigned long flags;
        int err;

        spin_lock_irqsave(&tdc->lock, flags);
        if (list_empty(&tdc->pending_sg_req)) {
                dev_err(tdc2dev(tdc), "No DMA request\n");
                goto end;
        }
        if (!tdc->busy) {
                err = pm_runtime_resume_and_get(tdc->tdma->dev);
                if (err < 0) {
                        dev_err(tdc2dev(tdc), "Failed to enable DMA\n");
                        goto end;
                }

                tdc_start_head_req(tdc);

                /* Continuous single mode: Configure next req */
                if (tdc->cyclic) {
                        /*
                         * Wait for 1 burst time for configure DMA for
                         * next transfer.
                         */
                        udelay(TEGRA_APBDMA_BURST_COMPLETE_TIME);
                        tdc_configure_next_head_desc(tdc);
                }
        }
end:
        spin_unlock_irqrestore(&tdc->lock, flags);
}

static int tegra_dma_terminate_all(struct dma_chan *dc)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
        struct tegra_dma_desc *dma_desc;
        struct tegra_dma_sg_req *sgreq;
        unsigned long flags;
        u32 status, wcount;
        bool was_busy;

        spin_lock_irqsave(&tdc->lock, flags);

        if (!tdc->busy)
                goto skip_dma_stop;

        /* Pause DMA before checking the queue status */
        tegra_dma_pause(tdc, true);

        status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);
        if (status & TEGRA_APBDMA_STATUS_ISE_EOC) {
                dev_dbg(tdc2dev(tdc), "%s():handling isr\n", __func__);
                tdc->isr_handler(tdc, true);
                status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);
        }
        if (tdc->tdma->chip_data->support_separate_wcount_reg)
                wcount = tdc_read(tdc, TEGRA_APBDMA_CHAN_WORD_TRANSFER);
        else
                wcount = status;

        was_busy = tdc->busy;
        tegra_dma_stop(tdc);

        if (!list_empty(&tdc->pending_sg_req) && was_busy) {
                sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq),
                                         node);
                sgreq->dma_desc->bytes_transferred +=
                                get_current_xferred_count(tdc, sgreq, wcount);
        }
        tegra_dma_resume(tdc);

        pm_runtime_put(tdc->tdma->dev);
        wake_up_all(&tdc->wq);

skip_dma_stop:
        tegra_dma_abort_all(tdc);

        while (!list_empty(&tdc->cb_desc)) {
                dma_desc = list_first_entry(&tdc->cb_desc, typeof(*dma_desc),
                                            cb_node);
                list_del(&dma_desc->cb_node);
                dma_desc->cb_count = 0;
        }
        spin_unlock_irqrestore(&tdc->lock, flags);

        return 0;
}

static bool tegra_dma_eoc_interrupt_deasserted(struct tegra_dma_channel *tdc)
{
        unsigned long flags;
        u32 status;

        spin_lock_irqsave(&tdc->lock, flags);
        status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);
        spin_unlock_irqrestore(&tdc->lock, flags);

        return !(status & TEGRA_APBDMA_STATUS_ISE_EOC);
}

static void tegra_dma_synchronize(struct dma_chan *dc)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
        int err;

        err = pm_runtime_resume_and_get(tdc->tdma->dev);
        if (err < 0) {
                dev_err(tdc2dev(tdc), "Failed to synchronize DMA: %d\n", err);
                return;
        }

        /*
         * CPU, which handles interrupt, could be busy in
         * uninterruptible state, in this case sibling CPU
         * should wait until interrupt is handled.
         */
        wait_event(tdc->wq, tegra_dma_eoc_interrupt_deasserted(tdc));

        tasklet_kill(&tdc->tasklet);

        pm_runtime_put(tdc->tdma->dev);
}

static unsigned int tegra_dma_sg_bytes_xferred(struct tegra_dma_channel *tdc,
                                               struct tegra_dma_sg_req *sg_req)
{
        u32 status, wcount = 0;

        if (!list_is_first(&sg_req->node, &tdc->pending_sg_req))
                return 0;

        if (tdc->tdma->chip_data->support_separate_wcount_reg)
                wcount = tdc_read(tdc, TEGRA_APBDMA_CHAN_WORD_TRANSFER);

        status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS);

        if (!tdc->tdma->chip_data->support_separate_wcount_reg)
                wcount = status;

        if (status & TEGRA_APBDMA_STATUS_ISE_EOC)
                return sg_req->req_len;

        wcount = get_current_xferred_count(tdc, sg_req, wcount);

        if (!wcount) {
                /*
                 * If wcount wasn't ever polled for this SG before, then
                 * simply assume that transfer hasn't started yet.
                 *
                 * Otherwise it's the end of the transfer.
                 *
                 * The alternative would be to poll the status register
                 * until EOC bit is set or wcount goes UP. That's so
                 * because EOC bit is getting set only after the last
                 * burst's completion and counter is less than the actual
                 * transfer size by 4 bytes. The counter value wraps around
                 * in a cyclic mode before EOC is set(!), so we can't easily
                 * distinguish start of transfer from its end.
                 */
                if (sg_req->words_xferred)
                        wcount = sg_req->req_len - 4;

        } else if (wcount < sg_req->words_xferred) {
                /*
                 * This case will never happen for a non-cyclic transfer.
                 *
                 * For a cyclic transfer, although it is possible for the
                 * next transfer to have already started (resetting the word
                 * count), this case should still not happen because we should
                 * have detected that the EOC bit is set and hence the transfer
                 * was completed.
                 */
                WARN_ON_ONCE(1);

                wcount = sg_req->req_len - 4;
        } else {
                sg_req->words_xferred = wcount;
        }

        return wcount;
}

static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
                                           dma_cookie_t cookie,
                                           struct dma_tx_state *txstate)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
        struct tegra_dma_desc *dma_desc;
        struct tegra_dma_sg_req *sg_req;
        enum dma_status ret;
        unsigned long flags;
        unsigned int residual;
        unsigned int bytes = 0;

        ret = dma_cookie_status(dc, cookie, txstate);
        if (ret == DMA_COMPLETE)
                return ret;

        spin_lock_irqsave(&tdc->lock, flags);

        /* Check on wait_ack desc status */
        list_for_each_entry(dma_desc, &tdc->free_dma_desc, node) {
                if (dma_desc->txd.cookie == cookie) {
                        ret = dma_desc->dma_status;
                        goto found;
                }
        }

        /* Check in pending list */
        list_for_each_entry(sg_req, &tdc->pending_sg_req, node) {
                dma_desc = sg_req->dma_desc;
                if (dma_desc->txd.cookie == cookie) {
                        bytes = tegra_dma_sg_bytes_xferred(tdc, sg_req);
                        ret = dma_desc->dma_status;
                        goto found;
                }
        }

        dev_dbg(tdc2dev(tdc), "cookie %d not found\n", cookie);
        dma_desc = NULL;

found:
        if (dma_desc && txstate) {
                residual = dma_desc->bytes_requested -
                           ((dma_desc->bytes_transferred + bytes) %
                            dma_desc->bytes_requested);
                dma_set_residue(txstate, residual);
        }

        trace_tegra_dma_tx_status(&tdc->dma_chan, cookie, txstate);
        spin_unlock_irqrestore(&tdc->lock, flags);

        return ret;
}

static inline unsigned int get_bus_width(struct tegra_dma_channel *tdc,
                                         enum dma_slave_buswidth slave_bw)
{
        switch (slave_bw) {
        case DMA_SLAVE_BUSWIDTH_1_BYTE:
                return TEGRA_APBDMA_APBSEQ_BUS_WIDTH_8;
        case DMA_SLAVE_BUSWIDTH_2_BYTES:
                return TEGRA_APBDMA_APBSEQ_BUS_WIDTH_16;
        case DMA_SLAVE_BUSWIDTH_4_BYTES:
                return TEGRA_APBDMA_APBSEQ_BUS_WIDTH_32;
        case DMA_SLAVE_BUSWIDTH_8_BYTES:
                return TEGRA_APBDMA_APBSEQ_BUS_WIDTH_64;
        default:
                dev_warn(tdc2dev(tdc),
                         "slave bw is not supported, using 32bits\n");
                return TEGRA_APBDMA_APBSEQ_BUS_WIDTH_32;
        }
}

static inline unsigned int get_burst_size(struct tegra_dma_channel *tdc,
                                          u32 burst_size,
                                          enum dma_slave_buswidth slave_bw,
                                          u32 len)
{
        unsigned int burst_byte, burst_ahb_width;

        /*
         * burst_size from client is in terms of the bus_width.
         * convert them into AHB memory width which is 4 byte.
         */
        burst_byte = burst_size * slave_bw;
        burst_ahb_width = burst_byte / 4;

        /* If burst size is 0 then calculate the burst size based on length */
        if (!burst_ahb_width) {
                if (len & 0xF)
                        return TEGRA_APBDMA_AHBSEQ_BURST_1;
                else if ((len >> 4) & 0x1)
                        return TEGRA_APBDMA_AHBSEQ_BURST_4;
                else
                        return TEGRA_APBDMA_AHBSEQ_BURST_8;
        }
        if (burst_ahb_width < 4)
                return TEGRA_APBDMA_AHBSEQ_BURST_1;
        else if (burst_ahb_width < 8)
                return TEGRA_APBDMA_AHBSEQ_BURST_4;
        else
                return TEGRA_APBDMA_AHBSEQ_BURST_8;
}

static int get_transfer_param(struct tegra_dma_channel *tdc,
                              enum dma_transfer_direction direction,
                              u32 *apb_addr,
                              u32 *apb_seq,
                              u32 *csr,
                              unsigned int *burst_size,
                              enum dma_slave_buswidth *slave_bw)
{
        switch (direction) {
        case DMA_MEM_TO_DEV:
                *apb_addr = tdc->dma_sconfig.dst_addr;
                *apb_seq = get_bus_width(tdc, tdc->dma_sconfig.dst_addr_width);
                *burst_size = tdc->dma_sconfig.dst_maxburst;
                *slave_bw = tdc->dma_sconfig.dst_addr_width;
                *csr = TEGRA_APBDMA_CSR_DIR;
                return 0;

        case DMA_DEV_TO_MEM:
                *apb_addr = tdc->dma_sconfig.src_addr;
                *apb_seq = get_bus_width(tdc, tdc->dma_sconfig.src_addr_width);
                *burst_size = tdc->dma_sconfig.src_maxburst;
                *slave_bw = tdc->dma_sconfig.src_addr_width;
                *csr = 0;
                return 0;

        default:
                dev_err(tdc2dev(tdc), "DMA direction is not supported\n");
                break;
        }

        return -EINVAL;
}

static void tegra_dma_prep_wcount(struct tegra_dma_channel *tdc,
                                  struct tegra_dma_channel_regs *ch_regs,
                                  u32 len)
{
        u32 len_field = (len - 4) & 0xFFFC;

        if (tdc->tdma->chip_data->support_separate_wcount_reg)
                ch_regs->wcount = len_field;
        else
                ch_regs->csr |= len_field;
}

static struct dma_async_tx_descriptor *
tegra_dma_prep_slave_sg(struct dma_chan *dc,
                        struct scatterlist *sgl,
                        unsigned int sg_len,
                        enum dma_transfer_direction direction,
                        unsigned long flags,
                        void *context)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
        struct tegra_dma_sg_req *sg_req = NULL;
        u32 csr, ahb_seq, apb_ptr, apb_seq;
        enum dma_slave_buswidth slave_bw;
        struct tegra_dma_desc *dma_desc;
        struct list_head req_list;
        struct scatterlist *sg;
        unsigned int burst_size;
        unsigned int i;

        if (!tdc->config_init) {
                dev_err(tdc2dev(tdc), "DMA channel is not configured\n");
                return NULL;
        }
        if (sg_len < 1) {
                dev_err(tdc2dev(tdc), "Invalid segment length %d\n", sg_len);
                return NULL;
        }

        if (get_transfer_param(tdc, direction, &apb_ptr, &apb_seq, &csr,
                               &burst_size, &slave_bw) < 0)
                return NULL;

        INIT_LIST_HEAD(&req_list);

        ahb_seq = TEGRA_APBDMA_AHBSEQ_INTR_ENB;
        ahb_seq |= TEGRA_APBDMA_AHBSEQ_WRAP_NONE <<
                                        TEGRA_APBDMA_AHBSEQ_WRAP_SHIFT;
        ahb_seq |= TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_32;

        csr |= TEGRA_APBDMA_CSR_ONCE;

        if (tdc->slave_id != TEGRA_APBDMA_SLAVE_ID_INVALID) {
                csr |= TEGRA_APBDMA_CSR_FLOW;
                csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
        }

        if (flags & DMA_PREP_INTERRUPT) {
                csr |= TEGRA_APBDMA_CSR_IE_EOC;
        } else {
                WARN_ON_ONCE(1);
                return NULL;
        }

        apb_seq |= TEGRA_APBDMA_APBSEQ_WRAP_WORD_1;

        dma_desc = tegra_dma_desc_get(tdc);
        if (!dma_desc) {
                dev_err(tdc2dev(tdc), "DMA descriptors not available\n");
                return NULL;
        }
        INIT_LIST_HEAD(&dma_desc->tx_list);
        INIT_LIST_HEAD(&dma_desc->cb_node);
        dma_desc->cb_count = 0;
        dma_desc->bytes_requested = 0;
        dma_desc->bytes_transferred = 0;
        dma_desc->dma_status = DMA_IN_PROGRESS;

        /* Make transfer requests */
        for_each_sg(sgl, sg, sg_len, i) {
                u32 len, mem;

                mem = sg_dma_address(sg);
                len = sg_dma_len(sg);

                if ((len & 3) || (mem & 3) ||
                    len > tdc->tdma->chip_data->max_dma_count) {
                        dev_err(tdc2dev(tdc),
                                "DMA length/memory address is not supported\n");
                        tegra_dma_desc_put(tdc, dma_desc);
                        return NULL;
                }

                sg_req = tegra_dma_sg_req_get(tdc);
                if (!sg_req) {
                        dev_err(tdc2dev(tdc), "DMA sg-req not available\n");
                        tegra_dma_desc_put(tdc, dma_desc);
                        return NULL;
                }

                ahb_seq |= get_burst_size(tdc, burst_size, slave_bw, len);
                dma_desc->bytes_requested += len;

                sg_req->ch_regs.apb_ptr = apb_ptr;
                sg_req->ch_regs.ahb_ptr = mem;
                sg_req->ch_regs.csr = csr;
                tegra_dma_prep_wcount(tdc, &sg_req->ch_regs, len);
                sg_req->ch_regs.apb_seq = apb_seq;
                sg_req->ch_regs.ahb_seq = ahb_seq;
                sg_req->configured = false;
                sg_req->last_sg = false;
                sg_req->dma_desc = dma_desc;
                sg_req->req_len = len;

                list_add_tail(&sg_req->node, &dma_desc->tx_list);
        }
        sg_req->last_sg = true;
        if (flags & DMA_CTRL_ACK)
                dma_desc->txd.flags = DMA_CTRL_ACK;

        /*
         * Make sure that mode should not be conflicting with currently
         * configured mode.
         */
        if (!tdc->isr_handler) {
                tdc->isr_handler = handle_once_dma_done;
                tdc->cyclic = false;
        } else {
                if (tdc->cyclic) {
                        dev_err(tdc2dev(tdc), "DMA configured in cyclic mode\n");
                        tegra_dma_desc_put(tdc, dma_desc);
                        return NULL;
                }
        }

        return &dma_desc->txd;
}

static struct dma_async_tx_descriptor *
tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr,
                          size_t buf_len,
                          size_t period_len,
                          enum dma_transfer_direction direction,
                          unsigned long flags)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
        struct tegra_dma_sg_req *sg_req = NULL;
        u32 csr, ahb_seq, apb_ptr, apb_seq;
        enum dma_slave_buswidth slave_bw;
        struct tegra_dma_desc *dma_desc;
        dma_addr_t mem = buf_addr;
        unsigned int burst_size;
        size_t len, remain_len;

        if (!buf_len || !period_len) {
                dev_err(tdc2dev(tdc), "Invalid buffer/period len\n");
                return NULL;
        }

        if (!tdc->config_init) {
                dev_err(tdc2dev(tdc), "DMA slave is not configured\n");
                return NULL;
        }

        /*
         * We allow to take more number of requests till DMA is
         * not started. The driver will loop over all requests.
         * Once DMA is started then new requests can be queued only after
         * terminating the DMA.
         */
        if (tdc->busy) {
                dev_err(tdc2dev(tdc), "Request not allowed when DMA running\n");
                return NULL;
        }

        /*
         * We only support cycle transfer when buf_len is multiple of
         * period_len.
         */
        if (buf_len % period_len) {
                dev_err(tdc2dev(tdc), "buf_len is not multiple of period_len\n");
                return NULL;
        }

        len = period_len;
        if ((len & 3) || (buf_addr & 3) ||
            len > tdc->tdma->chip_data->max_dma_count) {
                dev_err(tdc2dev(tdc), "Req len/mem address is not correct\n");
                return NULL;
        }

        if (get_transfer_param(tdc, direction, &apb_ptr, &apb_seq, &csr,
                               &burst_size, &slave_bw) < 0)
                return NULL;

        ahb_seq = TEGRA_APBDMA_AHBSEQ_INTR_ENB;
        ahb_seq |= TEGRA_APBDMA_AHBSEQ_WRAP_NONE <<
                                        TEGRA_APBDMA_AHBSEQ_WRAP_SHIFT;
        ahb_seq |= TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_32;

        if (tdc->slave_id != TEGRA_APBDMA_SLAVE_ID_INVALID) {
                csr |= TEGRA_APBDMA_CSR_FLOW;
                csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
        }

        if (flags & DMA_PREP_INTERRUPT) {
                csr |= TEGRA_APBDMA_CSR_IE_EOC;
        } else {
                WARN_ON_ONCE(1);
                return NULL;
        }

        apb_seq |= TEGRA_APBDMA_APBSEQ_WRAP_WORD_1;

        dma_desc = tegra_dma_desc_get(tdc);
        if (!dma_desc) {
                dev_err(tdc2dev(tdc), "not enough descriptors available\n");
                return NULL;
        }

        INIT_LIST_HEAD(&dma_desc->tx_list);
        INIT_LIST_HEAD(&dma_desc->cb_node);
        dma_desc->cb_count = 0;

        dma_desc->bytes_transferred = 0;
        dma_desc->bytes_requested = buf_len;
        remain_len = buf_len;

        /* Split transfer equal to period size */
        while (remain_len) {
                sg_req = tegra_dma_sg_req_get(tdc);
                if (!sg_req) {
                        dev_err(tdc2dev(tdc), "DMA sg-req not available\n");
                        tegra_dma_desc_put(tdc, dma_desc);
                        return NULL;
                }

                ahb_seq |= get_burst_size(tdc, burst_size, slave_bw, len);
                sg_req->ch_regs.apb_ptr = apb_ptr;
                sg_req->ch_regs.ahb_ptr = mem;
                sg_req->ch_regs.csr = csr;
                tegra_dma_prep_wcount(tdc, &sg_req->ch_regs, len);
                sg_req->ch_regs.apb_seq = apb_seq;
                sg_req->ch_regs.ahb_seq = ahb_seq;
                sg_req->configured = false;
                sg_req->last_sg = false;
                sg_req->dma_desc = dma_desc;
                sg_req->req_len = len;

                list_add_tail(&sg_req->node, &dma_desc->tx_list);
                remain_len -= len;
                mem += len;
        }
        sg_req->last_sg = true;
        if (flags & DMA_CTRL_ACK)
                dma_desc->txd.flags = DMA_CTRL_ACK;

        /*
         * Make sure that mode should not be conflicting with currently
         * configured mode.
         */
        if (!tdc->isr_handler) {
                tdc->isr_handler = handle_cont_sngl_cycle_dma_done;
                tdc->cyclic = true;
        } else {
                if (!tdc->cyclic) {
                        dev_err(tdc2dev(tdc), "DMA configuration conflict\n");
                        tegra_dma_desc_put(tdc, dma_desc);
                        return NULL;
                }
        }

        return &dma_desc->txd;
}

static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);

        dma_cookie_init(&tdc->dma_chan);

        return 0;
}

static void tegra_dma_free_chan_resources(struct dma_chan *dc)
{
        struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
        struct tegra_dma_desc *dma_desc;
        struct tegra_dma_sg_req *sg_req;
        struct list_head dma_desc_list;
        struct list_head sg_req_list;

        INIT_LIST_HEAD(&dma_desc_list);
        INIT_LIST_HEAD(&sg_req_list);

        dev_dbg(tdc2dev(tdc), "Freeing channel %d\n", tdc->id);

        tegra_dma_terminate_all(dc);
        tasklet_kill(&tdc->tasklet);

        list_splice_init(&tdc->pending_sg_req, &sg_req_list);
        list_splice_init(&tdc->free_sg_req, &sg_req_list);
        list_splice_init(&tdc->free_dma_desc, &dma_desc_list);
        INIT_LIST_HEAD(&tdc->cb_desc);
        tdc->config_init = false;
        tdc->isr_handler = NULL;

        while (!list_empty(&dma_desc_list)) {
                dma_desc = list_first_entry(&dma_desc_list, typeof(*dma_desc),
                                            node);
                list_del(&dma_desc->node);
                kfree(dma_desc);
        }

        while (!list_empty(&sg_req_list)) {
                sg_req = list_first_entry(&sg_req_list, typeof(*sg_req), node);
                list_del(&sg_req->node);
                kfree(sg_req);
        }

        tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;
}

static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
                                           struct of_dma *ofdma)
{
        struct tegra_dma *tdma = ofdma->of_dma_data;
        struct tegra_dma_channel *tdc;
        struct dma_chan *chan;

        if (dma_spec->args[0] > TEGRA_APBDMA_CSR_REQ_SEL_MASK) {
                dev_err(tdma->dev, "Invalid slave id: %d\n", dma_spec->args[0]);
                return NULL;
        }

        chan = dma_get_any_slave_channel(&tdma->dma_dev);
        if (!chan)
                return NULL;

        tdc = to_tegra_dma_chan(chan);
        tdc->slave_id = dma_spec->args[0];

        return chan;
}

/* Tegra20 specific DMA controller information */
static const struct tegra_dma_chip_data tegra20_dma_chip_data = {
        .nr_channels            = 16,
        .channel_reg_size       = 0x20,
        .max_dma_count          = 1024UL * 64,
        .support_channel_pause  = false,
        .support_separate_wcount_reg = false,
};

/* Tegra30 specific DMA controller information */
static const struct tegra_dma_chip_data tegra30_dma_chip_data = {
        .nr_channels            = 32,
        .channel_reg_size       = 0x20,
        .max_dma_count          = 1024UL * 64,
        .support_channel_pause  = false,
        .support_separate_wcount_reg = false,
};

/* Tegra114 specific DMA controller information */
static const struct tegra_dma_chip_data tegra114_dma_chip_data = {
        .nr_channels            = 32,
        .channel_reg_size       = 0x20,
        .max_dma_count          = 1024UL * 64,
        .support_channel_pause  = true,
        .support_separate_wcount_reg = false,
};

/* Tegra148 specific DMA controller information */
static const struct tegra_dma_chip_data tegra148_dma_chip_data = {
        .nr_channels            = 32,
        .channel_reg_size       = 0x40,
        .max_dma_count          = 1024UL * 64,
        .support_channel_pause  = true,
        .support_separate_wcount_reg = true,
};

static int tegra_dma_init_hw(struct tegra_dma *tdma)
{
        int err;

        err = reset_control_assert(tdma->rst);
        if (err) {
                dev_err(tdma->dev, "failed to assert reset: %d\n", err);
                return err;
        }

        err = clk_enable(tdma->dma_clk);
        if (err) {
                dev_err(tdma->dev, "failed to enable clk: %d\n", err);
                return err;
        }

        /* reset DMA controller */
        udelay(2);
        reset_control_deassert(tdma->rst);

        /* enable global DMA registers */
        tdma_write(tdma, TEGRA_APBDMA_GENERAL, TEGRA_APBDMA_GENERAL_ENABLE);
        tdma_write(tdma, TEGRA_APBDMA_CONTROL, 0);
        tdma_write(tdma, TEGRA_APBDMA_IRQ_MASK_SET, 0xFFFFFFFF);

        clk_disable(tdma->dma_clk);

        return 0;
}

static int tegra_dma_probe(struct platform_device *pdev)
{
        const struct tegra_dma_chip_data *cdata;
        struct tegra_dma *tdma;
        unsigned int i;
        size_t size;
        int ret;

        cdata = of_device_get_match_data(&pdev->dev);
        size = struct_size(tdma, channels, cdata->nr_channels);

        tdma = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
        if (!tdma)
                return -ENOMEM;

        tdma->dev = &pdev->dev;
        tdma->chip_data = cdata;
        platform_set_drvdata(pdev, tdma);

        tdma->base_addr = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(tdma->base_addr))
                return PTR_ERR(tdma->base_addr);

        tdma->dma_clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(tdma->dma_clk)) {
                dev_err(&pdev->dev, "Error: Missing controller clock\n");
                return PTR_ERR(tdma->dma_clk);
        }

        tdma->rst = devm_reset_control_get(&pdev->dev, "dma");
        if (IS_ERR(tdma->rst)) {
                dev_err(&pdev->dev, "Error: Missing reset\n");
                return PTR_ERR(tdma->rst);
        }

        spin_lock_init(&tdma->global_lock);

        ret = clk_prepare(tdma->dma_clk);
        if (ret)
                return ret;

        ret = tegra_dma_init_hw(tdma);
        if (ret)
                goto err_clk_unprepare;

        pm_runtime_irq_safe(&pdev->dev);
        pm_runtime_enable(&pdev->dev);

        INIT_LIST_HEAD(&tdma->dma_dev.channels);
        for (i = 0; i < cdata->nr_channels; i++) {
                struct tegra_dma_channel *tdc = &tdma->channels[i];
                int irq;

                tdc->chan_addr = tdma->base_addr +
                                 TEGRA_APBDMA_CHANNEL_BASE_ADD_OFFSET +
                                 (i * cdata->channel_reg_size);

                irq = platform_get_irq(pdev, i);
                if (irq < 0) {
                        ret = irq;
                        goto err_pm_disable;
                }

                snprintf(tdc->name, sizeof(tdc->name), "apbdma.%d", i);
                ret = devm_request_irq(&pdev->dev, irq, tegra_dma_isr, 0,
                                       tdc->name, tdc);
                if (ret) {
                        dev_err(&pdev->dev,
                                "request_irq failed with err %d channel %d\n",
                                ret, i);
                        goto err_pm_disable;
                }

                tdc->dma_chan.device = &tdma->dma_dev;
                dma_cookie_init(&tdc->dma_chan);
                list_add_tail(&tdc->dma_chan.device_node,
                              &tdma->dma_dev.channels);
                tdc->tdma = tdma;
                tdc->id = i;
                tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;

                tasklet_setup(&tdc->tasklet, tegra_dma_tasklet);
                spin_lock_init(&tdc->lock);
                init_waitqueue_head(&tdc->wq);

                INIT_LIST_HEAD(&tdc->pending_sg_req);
                INIT_LIST_HEAD(&tdc->free_sg_req);
                INIT_LIST_HEAD(&tdc->free_dma_desc);
                INIT_LIST_HEAD(&tdc->cb_desc);
        }

        dma_cap_set(DMA_SLAVE, tdma->dma_dev.cap_mask);
        dma_cap_set(DMA_PRIVATE, tdma->dma_dev.cap_mask);
        dma_cap_set(DMA_CYCLIC, tdma->dma_dev.cap_mask);

        tdma->global_pause_count = 0;
        tdma->dma_dev.dev = &pdev->dev;
        tdma->dma_dev.device_alloc_chan_resources =
                                        tegra_dma_alloc_chan_resources;
        tdma->dma_dev.device_free_chan_resources =
                                        tegra_dma_free_chan_resources;
        tdma->dma_dev.device_prep_slave_sg = tegra_dma_prep_slave_sg;
        tdma->dma_dev.device_prep_dma_cyclic = tegra_dma_prep_dma_cyclic;
        tdma->dma_dev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
                BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
                BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
                BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
        tdma->dma_dev.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
                BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
                BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
                BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
        tdma->dma_dev.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
        tdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
        tdma->dma_dev.device_config = tegra_dma_slave_config;
        tdma->dma_dev.device_terminate_all = tegra_dma_terminate_all;
        tdma->dma_dev.device_synchronize = tegra_dma_synchronize;
        tdma->dma_dev.device_tx_status = tegra_dma_tx_status;
        tdma->dma_dev.device_issue_pending = tegra_dma_issue_pending;

        ret = dma_async_device_register(&tdma->dma_dev);
        if (ret < 0) {
                dev_err(&pdev->dev,
                        "Tegra20 APB DMA driver registration failed %d\n", ret);
                goto err_pm_disable;
        }

        ret = of_dma_controller_register(pdev->dev.of_node,
                                         tegra_dma_of_xlate, tdma);
        if (ret < 0) {
                dev_err(&pdev->dev,
                        "Tegra20 APB DMA OF registration failed %d\n", ret);
                goto err_unregister_dma_dev;
        }

        dev_info(&pdev->dev, "Tegra20 APB DMA driver registered %u channels\n",
                 cdata->nr_channels);

        return 0;

err_unregister_dma_dev:
        dma_async_device_unregister(&tdma->dma_dev);

err_pm_disable:
        pm_runtime_disable(&pdev->dev);

err_clk_unprepare:
        clk_unprepare(tdma->dma_clk);

        return ret;
}

static int tegra_dma_remove(struct platform_device *pdev)
{
        struct tegra_dma *tdma = platform_get_drvdata(pdev);

        of_dma_controller_free(pdev->dev.of_node);
        dma_async_device_unregister(&tdma->dma_dev);
        pm_runtime_disable(&pdev->dev);
        clk_unprepare(tdma->dma_clk);

        return 0;
}

static int __maybe_unused tegra_dma_runtime_suspend(struct device *dev)
{
        struct tegra_dma *tdma = dev_get_drvdata(dev);

        clk_disable(tdma->dma_clk);

        return 0;
}

static int __maybe_unused tegra_dma_runtime_resume(struct device *dev)
{
        struct tegra_dma *tdma = dev_get_drvdata(dev);

        return clk_enable(tdma->dma_clk);
}

static int __maybe_unused tegra_dma_dev_suspend(struct device *dev)
{
        struct tegra_dma *tdma = dev_get_drvdata(dev);
        unsigned long flags;
        unsigned int i;
        bool busy;

        for (i = 0; i < tdma->chip_data->nr_channels; i++) {
                struct tegra_dma_channel *tdc = &tdma->channels[i];

                tasklet_kill(&tdc->tasklet);

                spin_lock_irqsave(&tdc->lock, flags);
                busy = tdc->busy;
                spin_unlock_irqrestore(&tdc->lock, flags);

                if (busy) {
                        dev_err(tdma->dev, "channel %u busy\n", i);
                        return -EBUSY;
                }
        }

        return pm_runtime_force_suspend(dev);
}

static int __maybe_unused tegra_dma_dev_resume(struct device *dev)
{
        struct tegra_dma *tdma = dev_get_drvdata(dev);
        int err;

        err = tegra_dma_init_hw(tdma);
        if (err)
                return err;

        return pm_runtime_force_resume(dev);
}

static const struct dev_pm_ops tegra_dma_dev_pm_ops = {
        SET_RUNTIME_PM_OPS(tegra_dma_runtime_suspend, tegra_dma_runtime_resume,
                           NULL)
        SET_SYSTEM_SLEEP_PM_OPS(tegra_dma_dev_suspend, tegra_dma_dev_resume)
};

static const struct of_device_id tegra_dma_of_match[] = {
        {
                .compatible = "nvidia,tegra148-apbdma",
                .data = &tegra148_dma_chip_data,
        }, {
                .compatible = "nvidia,tegra114-apbdma",
                .data = &tegra114_dma_chip_data,
        }, {
                .compatible = "nvidia,tegra30-apbdma",
                .data = &tegra30_dma_chip_data,
        }, {
                .compatible = "nvidia,tegra20-apbdma",
                .data = &tegra20_dma_chip_data,
        }, {
        },
};
MODULE_DEVICE_TABLE(of, tegra_dma_of_match);

static struct platform_driver tegra_dmac_driver = {
        .driver = {
                .name   = "tegra-apbdma",
                .pm     = &tegra_dma_dev_pm_ops,
                .of_match_table = tegra_dma_of_match,
        },
        .probe          = tegra_dma_probe,
        .remove         = tegra_dma_remove,
};

module_platform_driver(tegra_dmac_driver);

MODULE_DESCRIPTION("NVIDIA Tegra APB DMA Controller driver");
MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");