/*
 * linux/arch/arm/plat-omap/dma.c
 *
 * Copyright (C) 2003 - 2008 Nokia Corporation
 * Author: Juha Yrjölä <juha.yrjola@nokia.com>
 * DMA channel linking for 1610 by Samuel Ortiz <samuel.ortiz@nokia.com>
 * Graphics DMA and LCD DMA graphics tranformations
 * by Imre Deak <imre.deak@nokia.com>
 * OMAP2/3 support Copyright (C) 2004-2007 Texas Instruments, Inc.
 * Merged to support both OMAP1 and OMAP2 by Tony Lindgren <tony@atomide.com>
 * Some functions based on earlier dma-omap.c Copyright (C) 2001 RidgeRun, Inc.
 *
 * Copyright (C) 2009 Texas Instruments
 * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
 *
 * Support functions for the OMAP internal DMA channels.
 *
 * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com/
 * Converted DMA library into DMA platform driver.
 *      - G, Manjunath Kondaiah <manjugk@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/delay.h>

#include <linux/omap-dma.h>

/*
 * MAX_LOGICAL_DMA_CH_COUNT: the maximum number of logical DMA
 * channels that an instance of the SDMA IP block can support.  Used
 * to size arrays.  (The actual maximum on a particular SoC may be less
 * than this -- for example, OMAP1 SDMA instances only support 17 logical
 * DMA channels.)
 */
#define MAX_LOGICAL_DMA_CH_COUNT                32

#undef DEBUG

#ifndef CONFIG_ARCH_OMAP1
enum { DMA_CH_ALLOC_DONE, DMA_CH_PARAMS_SET_DONE, DMA_CH_STARTED,
        DMA_CH_QUEUED, DMA_CH_NOTSTARTED, DMA_CH_PAUSED, DMA_CH_LINK_ENABLED
};

enum { DMA_CHAIN_STARTED, DMA_CHAIN_NOTSTARTED };
#endif

#define OMAP_DMA_ACTIVE                 0x01
#define OMAP2_DMA_CSR_CLEAR_MASK        0xffffffff

#define OMAP_FUNC_MUX_ARM_BASE          (0xfffe1000 + 0xec)

static struct omap_system_dma_plat_info *p;
static struct omap_dma_dev_attr *d;

static int enable_1510_mode;
static u32 errata;

static struct omap_dma_global_context_registers {
        u32 dma_irqenable_l0;
        u32 dma_ocp_sysconfig;
        u32 dma_gcr;
} omap_dma_global_context;

struct dma_link_info {
        int *linked_dmach_q;
        int no_of_lchs_linked;

        int q_count;
        int q_tail;
        int q_head;

        int chain_state;
        int chain_mode;

};

static struct dma_link_info *dma_linked_lch;

#ifndef CONFIG_ARCH_OMAP1

/* Chain handling macros */
#define OMAP_DMA_CHAIN_QINIT(chain_id)                                  \
        do {                                                            \
                dma_linked_lch[chain_id].q_head =                       \
                dma_linked_lch[chain_id].q_tail =                       \
                dma_linked_lch[chain_id].q_count = 0;                   \
        } while (0)
#define OMAP_DMA_CHAIN_QFULL(chain_id)                                  \
                (dma_linked_lch[chain_id].no_of_lchs_linked ==          \
                dma_linked_lch[chain_id].q_count)
#define OMAP_DMA_CHAIN_QLAST(chain_id)                                  \
        do {                                                            \
                ((dma_linked_lch[chain_id].no_of_lchs_linked-1) ==      \
                dma_linked_lch[chain_id].q_count)                       \
        } while (0)
#define OMAP_DMA_CHAIN_QEMPTY(chain_id)                                 \
                (0 == dma_linked_lch[chain_id].q_count)
#define __OMAP_DMA_CHAIN_INCQ(end)                                      \
        ((end) = ((end)+1) % dma_linked_lch[chain_id].no_of_lchs_linked)
#define OMAP_DMA_CHAIN_INCQHEAD(chain_id)                               \
        do {                                                            \
                __OMAP_DMA_CHAIN_INCQ(dma_linked_lch[chain_id].q_head); \
                dma_linked_lch[chain_id].q_count--;                     \
        } while (0)

#define OMAP_DMA_CHAIN_INCQTAIL(chain_id)                               \
        do {                                                            \
                __OMAP_DMA_CHAIN_INCQ(dma_linked_lch[chain_id].q_tail); \
                dma_linked_lch[chain_id].q_count++; \
        } while (0)
#endif

static int dma_lch_count;
static int dma_chan_count;
static int omap_dma_reserve_channels;

static spinlock_t dma_chan_lock;
static struct omap_dma_lch *dma_chan;

static inline void disable_lnk(int lch);
static void omap_disable_channel_irq(int lch);
static inline void omap_enable_channel_irq(int lch);

#define REVISIT_24XX()          printk(KERN_ERR "FIXME: no %s on 24xx\n", \
                                                __func__);

#ifdef CONFIG_ARCH_OMAP15XX
/* Returns 1 if the DMA module is in OMAP1510-compatible mode, 0 otherwise */
static int omap_dma_in_1510_mode(void)
{
        return enable_1510_mode;
}
#else
#define omap_dma_in_1510_mode()         0
#endif

#ifdef CONFIG_ARCH_OMAP1
static inline int get_gdma_dev(int req)
{
        u32 reg = OMAP_FUNC_MUX_ARM_BASE + ((req - 1) / 5) * 4;
        int shift = ((req - 1) % 5) * 6;

        return ((omap_readl(reg) >> shift) & 0x3f) + 1;
}

static inline void set_gdma_dev(int req, int dev)
{
        u32 reg = OMAP_FUNC_MUX_ARM_BASE + ((req - 1) / 5) * 4;
        int shift = ((req - 1) % 5) * 6;
        u32 l;

        l = omap_readl(reg);
        l &= ~(0x3f << shift);
        l |= (dev - 1) << shift;
        omap_writel(l, reg);
}
#else
#define set_gdma_dev(req, dev)  do {} while (0)
#define omap_readl(reg)         0
#define omap_writel(val, reg)   do {} while (0)
#endif

#ifdef CONFIG_ARCH_OMAP1
void omap_set_dma_priority(int lch, int dst_port, int priority)
{
        unsigned long reg;
        u32 l;

        if (dma_omap1()) {
                switch (dst_port) {
                case OMAP_DMA_PORT_OCP_T1:      /* FFFECC00 */
                        reg = OMAP_TC_OCPT1_PRIOR;
                        break;
                case OMAP_DMA_PORT_OCP_T2:      /* FFFECCD0 */
                        reg = OMAP_TC_OCPT2_PRIOR;
                        break;
                case OMAP_DMA_PORT_EMIFF:       /* FFFECC08 */
                        reg = OMAP_TC_EMIFF_PRIOR;
                        break;
                case OMAP_DMA_PORT_EMIFS:       /* FFFECC04 */
                        reg = OMAP_TC_EMIFS_PRIOR;
                        break;
                default:
                        BUG();
                        return;
                }
                l = omap_readl(reg);
                l &= ~(0xf << 8);
                l |= (priority & 0xf) << 8;
                omap_writel(l, reg);
        }
}
#endif

#ifdef CONFIG_ARCH_OMAP2PLUS
void omap_set_dma_priority(int lch, int dst_port, int priority)
{
        u32 ccr;

        ccr = p->dma_read(CCR, lch);
        if (priority)
                ccr |= (1 << 6);
        else
                ccr &= ~(1 << 6);
        p->dma_write(ccr, CCR, lch);
}
#endif
EXPORT_SYMBOL(omap_set_dma_priority);

void omap_set_dma_transfer_params(int lch, int data_type, int elem_count,
                                  int frame_count, int sync_mode,
                                  int dma_trigger, int src_or_dst_synch)
{
        u32 l;

        l = p->dma_read(CSDP, lch);
        l &= ~0x03;
        l |= data_type;
        p->dma_write(l, CSDP, lch);

        if (dma_omap1()) {
                u16 ccr;

                ccr = p->dma_read(CCR, lch);
                ccr &= ~(1 << 5);
                if (sync_mode == OMAP_DMA_SYNC_FRAME)
                        ccr |= 1 << 5;
                p->dma_write(ccr, CCR, lch);

                ccr = p->dma_read(CCR2, lch);
                ccr &= ~(1 << 2);
                if (sync_mode == OMAP_DMA_SYNC_BLOCK)
                        ccr |= 1 << 2;
                p->dma_write(ccr, CCR2, lch);
        }

        if (dma_omap2plus() && dma_trigger) {
                u32 val;

                val = p->dma_read(CCR, lch);

                /* DMA_SYNCHRO_CONTROL_UPPER depends on the channel number */
                val &= ~((1 << 23) | (3 << 19) | 0x1f);
                val |= (dma_trigger & ~0x1f) << 14;
                val |= dma_trigger & 0x1f;

                if (sync_mode & OMAP_DMA_SYNC_FRAME)
                        val |= 1 << 5;
                else
                        val &= ~(1 << 5);

                if (sync_mode & OMAP_DMA_SYNC_BLOCK)
                        val |= 1 << 18;
                else
                        val &= ~(1 << 18);

                if (src_or_dst_synch == OMAP_DMA_DST_SYNC_PREFETCH) {
                        val &= ~(1 << 24);      /* dest synch */
                        val |= (1 << 23);       /* Prefetch */
                } else if (src_or_dst_synch) {
                        val |= 1 << 24;         /* source synch */
                } else {
                        val &= ~(1 << 24);      /* dest synch */
                }
                p->dma_write(val, CCR, lch);
        }

        p->dma_write(elem_count, CEN, lch);
        p->dma_write(frame_count, CFN, lch);
}
EXPORT_SYMBOL(omap_set_dma_transfer_params);

void omap_set_dma_color_mode(int lch, enum omap_dma_color_mode mode, u32 color)
{
        BUG_ON(omap_dma_in_1510_mode());

        if (dma_omap1()) {
                u16 w;

                w = p->dma_read(CCR2, lch);
                w &= ~0x03;

                switch (mode) {
                case OMAP_DMA_CONSTANT_FILL:
                        w |= 0x01;
                        break;
                case OMAP_DMA_TRANSPARENT_COPY:
                        w |= 0x02;
                        break;
                case OMAP_DMA_COLOR_DIS:
                        break;
                default:
                        BUG();
                }
                p->dma_write(w, CCR2, lch);

                w = p->dma_read(LCH_CTRL, lch);
                w &= ~0x0f;
                /* Default is channel type 2D */
                if (mode) {
                        p->dma_write(color, COLOR, lch);
                        w |= 1;         /* Channel type G */
                }
                p->dma_write(w, LCH_CTRL, lch);
        }

        if (dma_omap2plus()) {
                u32 val;

                val = p->dma_read(CCR, lch);
                val &= ~((1 << 17) | (1 << 16));

                switch (mode) {
                case OMAP_DMA_CONSTANT_FILL:
                        val |= 1 << 16;
                        break;
                case OMAP_DMA_TRANSPARENT_COPY:
                        val |= 1 << 17;
                        break;
                case OMAP_DMA_COLOR_DIS:
                        break;
                default:
                        BUG();
                }
                p->dma_write(val, CCR, lch);

                color &= 0xffffff;
                p->dma_write(color, COLOR, lch);
        }
}
EXPORT_SYMBOL(omap_set_dma_color_mode);

void omap_set_dma_write_mode(int lch, enum omap_dma_write_mode mode)
{
        if (dma_omap2plus()) {
                u32 csdp;

                csdp = p->dma_read(CSDP, lch);
                csdp &= ~(0x3 << 16);
                csdp |= (mode << 16);
                p->dma_write(csdp, CSDP, lch);
        }
}
EXPORT_SYMBOL(omap_set_dma_write_mode);

void omap_set_dma_channel_mode(int lch, enum omap_dma_channel_mode mode)
{
        if (dma_omap1() && !dma_omap15xx()) {
                u32 l;

                l = p->dma_read(LCH_CTRL, lch);
                l &= ~0x7;
                l |= mode;
                p->dma_write(l, LCH_CTRL, lch);
        }
}
EXPORT_SYMBOL(omap_set_dma_channel_mode);

/* Note that src_port is only for omap1 */
void omap_set_dma_src_params(int lch, int src_port, int src_amode,
                             unsigned long src_start,
                             int src_ei, int src_fi)
{
        u32 l;

        if (dma_omap1()) {
                u16 w;

                w = p->dma_read(CSDP, lch);
                w &= ~(0x1f << 2);
                w |= src_port << 2;
                p->dma_write(w, CSDP, lch);
        }

        l = p->dma_read(CCR, lch);
        l &= ~(0x03 << 12);
        l |= src_amode << 12;
        p->dma_write(l, CCR, lch);

        p->dma_write(src_start, CSSA, lch);

        p->dma_write(src_ei, CSEI, lch);
        p->dma_write(src_fi, CSFI, lch);
}
EXPORT_SYMBOL(omap_set_dma_src_params);

void omap_set_dma_params(int lch, struct omap_dma_channel_params *params)
{
        omap_set_dma_transfer_params(lch, params->data_type,
                                     params->elem_count, params->frame_count,
                                     params->sync_mode, params->trigger,
                                     params->src_or_dst_synch);
        omap_set_dma_src_params(lch, params->src_port,
                                params->src_amode, params->src_start,
                                params->src_ei, params->src_fi);

        omap_set_dma_dest_params(lch, params->dst_port,
                                 params->dst_amode, params->dst_start,
                                 params->dst_ei, params->dst_fi);
        if (params->read_prio || params->write_prio)
                omap_dma_set_prio_lch(lch, params->read_prio,
                                      params->write_prio);
}
EXPORT_SYMBOL(omap_set_dma_params);

void omap_set_dma_src_index(int lch, int eidx, int fidx)
{
        if (dma_omap2plus())
                return;

        p->dma_write(eidx, CSEI, lch);
        p->dma_write(fidx, CSFI, lch);
}
EXPORT_SYMBOL(omap_set_dma_src_index);

void omap_set_dma_src_data_pack(int lch, int enable)
{
        u32 l;

        l = p->dma_read(CSDP, lch);
        l &= ~(1 << 6);
        if (enable)
                l |= (1 << 6);
        p->dma_write(l, CSDP, lch);
}
EXPORT_SYMBOL(omap_set_dma_src_data_pack);

void omap_set_dma_src_burst_mode(int lch, enum omap_dma_burst_mode burst_mode)
{
        unsigned int burst = 0;
        u32 l;

        l = p->dma_read(CSDP, lch);
        l &= ~(0x03 << 7);

        switch (burst_mode) {
        case OMAP_DMA_DATA_BURST_DIS:
                break;
        case OMAP_DMA_DATA_BURST_4:
                if (dma_omap2plus())
                        burst = 0x1;
                else
                        burst = 0x2;
                break;
        case OMAP_DMA_DATA_BURST_8:
                if (dma_omap2plus()) {
                        burst = 0x2;
                        break;
                }
                /*
                 * not supported by current hardware on OMAP1
                 * w |= (0x03 << 7);
                 * fall through
                 */
        case OMAP_DMA_DATA_BURST_16:
                if (dma_omap2plus()) {
                        burst = 0x3;
                        break;
                }
                /*
                 * OMAP1 don't support burst 16
                 * fall through
                 */
        default:
                BUG();
        }

        l |= (burst << 7);
        p->dma_write(l, CSDP, lch);
}
EXPORT_SYMBOL(omap_set_dma_src_burst_mode);

/* Note that dest_port is only for OMAP1 */
void omap_set_dma_dest_params(int lch, int dest_port, int dest_amode,
                              unsigned long dest_start,
                              int dst_ei, int dst_fi)
{
        u32 l;

        if (dma_omap1()) {
                l = p->dma_read(CSDP, lch);
                l &= ~(0x1f << 9);
                l |= dest_port << 9;
                p->dma_write(l, CSDP, lch);
        }

        l = p->dma_read(CCR, lch);
        l &= ~(0x03 << 14);
        l |= dest_amode << 14;
        p->dma_write(l, CCR, lch);

        p->dma_write(dest_start, CDSA, lch);

        p->dma_write(dst_ei, CDEI, lch);
        p->dma_write(dst_fi, CDFI, lch);
}
EXPORT_SYMBOL(omap_set_dma_dest_params);

void omap_set_dma_dest_index(int lch, int eidx, int fidx)
{
        if (dma_omap2plus())
                return;

        p->dma_write(eidx, CDEI, lch);
        p->dma_write(fidx, CDFI, lch);
}
EXPORT_SYMBOL(omap_set_dma_dest_index);

void omap_set_dma_dest_data_pack(int lch, int enable)
{
        u32 l;

        l = p->dma_read(CSDP, lch);
        l &= ~(1 << 13);
        if (enable)
                l |= 1 << 13;
        p->dma_write(l, CSDP, lch);
}
EXPORT_SYMBOL(omap_set_dma_dest_data_pack);

void omap_set_dma_dest_burst_mode(int lch, enum omap_dma_burst_mode burst_mode)
{
        unsigned int burst = 0;
        u32 l;

        l = p->dma_read(CSDP, lch);
        l &= ~(0x03 << 14);

        switch (burst_mode) {
        case OMAP_DMA_DATA_BURST_DIS:
                break;
        case OMAP_DMA_DATA_BURST_4:
                if (dma_omap2plus())
                        burst = 0x1;
                else
                        burst = 0x2;
                break;
        case OMAP_DMA_DATA_BURST_8:
                if (dma_omap2plus())
                        burst = 0x2;
                else
                        burst = 0x3;
                break;
        case OMAP_DMA_DATA_BURST_16:
                if (dma_omap2plus()) {
                        burst = 0x3;
                        break;
                }
                /*
                 * OMAP1 don't support burst 16
                 * fall through
                 */
        default:
                printk(KERN_ERR "Invalid DMA burst mode\n");
                BUG();
                return;
        }
        l |= (burst << 14);
        p->dma_write(l, CSDP, lch);
}
EXPORT_SYMBOL(omap_set_dma_dest_burst_mode);

static inline void omap_enable_channel_irq(int lch)
{
        /* Clear CSR */
        if (dma_omap1())
                p->dma_read(CSR, lch);
        else
                p->dma_write(OMAP2_DMA_CSR_CLEAR_MASK, CSR, lch);

        /* Enable some nice interrupts. */
        p->dma_write(dma_chan[lch].enabled_irqs, CICR, lch);
}

static inline void omap_disable_channel_irq(int lch)
{
        /* disable channel interrupts */
        p->dma_write(0, CICR, lch);
        /* Clear CSR */
        if (dma_omap1())
                p->dma_read(CSR, lch);
        else
                p->dma_write(OMAP2_DMA_CSR_CLEAR_MASK, CSR, lch);
}

void omap_enable_dma_irq(int lch, u16 bits)
{
        dma_chan[lch].enabled_irqs |= bits;
}
EXPORT_SYMBOL(omap_enable_dma_irq);

void omap_disable_dma_irq(int lch, u16 bits)
{
        dma_chan[lch].enabled_irqs &= ~bits;
}
EXPORT_SYMBOL(omap_disable_dma_irq);

static inline void enable_lnk(int lch)
{
        u32 l;

        l = p->dma_read(CLNK_CTRL, lch);

        if (dma_omap1())
                l &= ~(1 << 14);

        /* Set the ENABLE_LNK bits */
        if (dma_chan[lch].next_lch != -1)
                l = dma_chan[lch].next_lch | (1 << 15);

#ifndef CONFIG_ARCH_OMAP1
        if (dma_omap2plus())
                if (dma_chan[lch].next_linked_ch != -1)
                        l = dma_chan[lch].next_linked_ch | (1 << 15);
#endif

        p->dma_write(l, CLNK_CTRL, lch);
}

static inline void disable_lnk(int lch)
{
        u32 l;

        l = p->dma_read(CLNK_CTRL, lch);

        /* Disable interrupts */
        omap_disable_channel_irq(lch);

        if (dma_omap1()) {
                /* Set the STOP_LNK bit */
                l |= 1 << 14;
        }

        if (dma_omap2plus()) {
                /* Clear the ENABLE_LNK bit */
                l &= ~(1 << 15);
        }

        p->dma_write(l, CLNK_CTRL, lch);
        dma_chan[lch].flags &= ~OMAP_DMA_ACTIVE;
}

static inline void omap2_enable_irq_lch(int lch)
{
        u32 val;
        unsigned long flags;

        if (dma_omap1())
                return;

        spin_lock_irqsave(&dma_chan_lock, flags);
        /* clear IRQ STATUS */
        p->dma_write(1 << lch, IRQSTATUS_L0, lch);
        /* Enable interrupt */
        val = p->dma_read(IRQENABLE_L0, lch);
        val |= 1 << lch;
        p->dma_write(val, IRQENABLE_L0, lch);
        spin_unlock_irqrestore(&dma_chan_lock, flags);
}

static inline void omap2_disable_irq_lch(int lch)
{
        u32 val;
        unsigned long flags;

        if (dma_omap1())
                return;

        spin_lock_irqsave(&dma_chan_lock, flags);
        /* Disable interrupt */
        val = p->dma_read(IRQENABLE_L0, lch);
        val &= ~(1 << lch);
        p->dma_write(val, IRQENABLE_L0, lch);
        /* clear IRQ STATUS */
        p->dma_write(1 << lch, IRQSTATUS_L0, lch);
        spin_unlock_irqrestore(&dma_chan_lock, flags);
}

int omap_request_dma(int dev_id, const char *dev_name,
                     void (*callback)(int lch, u16 ch_status, void *data),
                     void *data, int *dma_ch_out)
{
        int ch, free_ch = -1;
        unsigned long flags;
        struct omap_dma_lch *chan;

        spin_lock_irqsave(&dma_chan_lock, flags);
        for (ch = 0; ch < dma_chan_count; ch++) {
                if (free_ch == -1 && dma_chan[ch].dev_id == -1) {
                        free_ch = ch;
                        /* Exit after first free channel found */
                        break;
                }
        }
        if (free_ch == -1) {
                spin_unlock_irqrestore(&dma_chan_lock, flags);
                return -EBUSY;
        }
        chan = dma_chan + free_ch;
        chan->dev_id = dev_id;

        if (p->clear_lch_regs)
                p->clear_lch_regs(free_ch);

        if (dma_omap2plus())
                omap_clear_dma(free_ch);

        spin_unlock_irqrestore(&dma_chan_lock, flags);

        chan->dev_name = dev_name;
        chan->callback = callback;
        chan->data = data;
        chan->flags = 0;

#ifndef CONFIG_ARCH_OMAP1
        if (dma_omap2plus()) {
                chan->chain_id = -1;
                chan->next_linked_ch = -1;
        }
#endif

        chan->enabled_irqs = OMAP_DMA_DROP_IRQ | OMAP_DMA_BLOCK_IRQ;

        if (dma_omap1())
                chan->enabled_irqs |= OMAP1_DMA_TOUT_IRQ;
        else if (dma_omap2plus())
                chan->enabled_irqs |= OMAP2_DMA_MISALIGNED_ERR_IRQ |
                        OMAP2_DMA_TRANS_ERR_IRQ;

        if (dma_omap16xx()) {
                /* If the sync device is set, configure it dynamically. */
                if (dev_id != 0) {
                        set_gdma_dev(free_ch + 1, dev_id);
                        dev_id = free_ch + 1;
                }
                /*
                 * Disable the 1510 compatibility mode and set the sync device
                 * id.
                 */
                p->dma_write(dev_id | (1 << 10), CCR, free_ch);
        } else if (dma_omap1()) {
                p->dma_write(dev_id, CCR, free_ch);
        }

        if (dma_omap2plus()) {
                omap_enable_channel_irq(free_ch);
                omap2_enable_irq_lch(free_ch);
        }

        *dma_ch_out = free_ch;

        return 0;
}
EXPORT_SYMBOL(omap_request_dma);

void omap_free_dma(int lch)
{
        unsigned long flags;

        if (dma_chan[lch].dev_id == -1) {
                pr_err("omap_dma: trying to free unallocated DMA channel %d\n",
                       lch);
                return;
        }

        /* Disable interrupt for logical channel */
        if (dma_omap2plus())
                omap2_disable_irq_lch(lch);

        /* Disable all DMA interrupts for the channel. */
        omap_disable_channel_irq(lch);

        /* Make sure the DMA transfer is stopped. */
        p->dma_write(0, CCR, lch);

        /* Clear registers */
        if (dma_omap2plus())
                omap_clear_dma(lch);

        spin_lock_irqsave(&dma_chan_lock, flags);
        dma_chan[lch].dev_id = -1;
        dma_chan[lch].next_lch = -1;
        dma_chan[lch].callback = NULL;
        spin_unlock_irqrestore(&dma_chan_lock, flags);
}
EXPORT_SYMBOL(omap_free_dma);

/**
 * @brief omap_dma_set_global_params : Set global priority settings for dma
 *
 * @param arb_rate
 * @param max_fifo_depth
 * @param tparams - Number of threads to reserve : DMA_THREAD_RESERVE_NORM
 *                                                 DMA_THREAD_RESERVE_ONET
 *                                                 DMA_THREAD_RESERVE_TWOT
 *                                                 DMA_THREAD_RESERVE_THREET
 */
void
omap_dma_set_global_params(int arb_rate, int max_fifo_depth, int tparams)
{
        u32 reg;

        if (dma_omap1()) {
                printk(KERN_ERR "FIXME: no %s on 15xx/16xx\n", __func__);
                return;
        }

        if (max_fifo_depth == 0)
                max_fifo_depth = 1;
        if (arb_rate == 0)
                arb_rate = 1;

        reg = 0xff & max_fifo_depth;
        reg |= (0x3 & tparams) << 12;
        reg |= (arb_rate & 0xff) << 16;

        p->dma_write(reg, GCR, 0);
}
EXPORT_SYMBOL(omap_dma_set_global_params);

/**
 * @brief omap_dma_set_prio_lch : Set channel wise priority settings
 *
 * @param lch
 * @param read_prio - Read priority
 * @param write_prio - Write priority
 * Both of the above can be set with one of the following values :
 *      DMA_CH_PRIO_HIGH/DMA_CH_PRIO_LOW
 */
int
omap_dma_set_prio_lch(int lch, unsigned char read_prio,
                      unsigned char write_prio)
{
        u32 l;

        if (unlikely((lch < 0 || lch >= dma_lch_count))) {
                printk(KERN_ERR "Invalid channel id\n");
                return -EINVAL;
        }
        l = p->dma_read(CCR, lch);
        l &= ~((1 << 6) | (1 << 26));
        if (d->dev_caps & IS_RW_PRIORITY)
                l |= ((read_prio & 0x1) << 6) | ((write_prio & 0x1) << 26);
        else
                l |= ((read_prio & 0x1) << 6);

        p->dma_write(l, CCR, lch);

        return 0;
}
EXPORT_SYMBOL(omap_dma_set_prio_lch);

/*
 * Clears any DMA state so the DMA engine is ready to restart with new buffers
 * through omap_start_dma(). Any buffers in flight are discarded.
 */
void omap_clear_dma(int lch)
{
        unsigned long flags;

        local_irq_save(flags);
        p->clear_dma(lch);
        local_irq_restore(flags);
}
EXPORT_SYMBOL(omap_clear_dma);

void omap_start_dma(int lch)
{
        u32 l;

        /*
         * The CPC/CDAC register needs to be initialized to zero
         * before starting dma transfer.
         */
        if (dma_omap15xx())
                p->dma_write(0, CPC, lch);
        else
                p->dma_write(0, CDAC, lch);

        if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1) {
                int next_lch, cur_lch;
                char dma_chan_link_map[MAX_LOGICAL_DMA_CH_COUNT];

                /* Set the link register of the first channel */
                enable_lnk(lch);

                memset(dma_chan_link_map, 0, sizeof(dma_chan_link_map));
                dma_chan_link_map[lch] = 1;

                cur_lch = dma_chan[lch].next_lch;
                do {
                        next_lch = dma_chan[cur_lch].next_lch;

                        /* The loop case: we've been here already */
                        if (dma_chan_link_map[cur_lch])
                                break;
                        /* Mark the current channel */
                        dma_chan_link_map[cur_lch] = 1;

                        enable_lnk(cur_lch);
                        omap_enable_channel_irq(cur_lch);

                        cur_lch = next_lch;
                } while (next_lch != -1);
        } else if (IS_DMA_ERRATA(DMA_ERRATA_PARALLEL_CHANNELS))
                p->dma_write(lch, CLNK_CTRL, lch);

        omap_enable_channel_irq(lch);

        l = p->dma_read(CCR, lch);

        if (IS_DMA_ERRATA(DMA_ERRATA_IFRAME_BUFFERING))
                        l |= OMAP_DMA_CCR_BUFFERING_DISABLE;
        l |= OMAP_DMA_CCR_EN;

        /*
         * As dma_write() uses IO accessors which are weakly ordered, there
         * is no guarantee that data in coherent DMA memory will be visible
         * to the DMA device.  Add a memory barrier here to ensure that any
         * such data is visible prior to enabling DMA.
         */
        mb();
        p->dma_write(l, CCR, lch);

        dma_chan[lch].flags |= OMAP_DMA_ACTIVE;
}
EXPORT_SYMBOL(omap_start_dma);

void omap_stop_dma(int lch)
{
        u32 l;

        /* Disable all interrupts on the channel */
        omap_disable_channel_irq(lch);

        l = p->dma_read(CCR, lch);
        if (IS_DMA_ERRATA(DMA_ERRATA_i541) &&
                        (l & OMAP_DMA_CCR_SEL_SRC_DST_SYNC)) {
                int i = 0;
                u32 sys_cf;

                /* Configure No-Standby */
                l = p->dma_read(OCP_SYSCONFIG, lch);
                sys_cf = l;
                l &= ~DMA_SYSCONFIG_MIDLEMODE_MASK;
                l |= DMA_SYSCONFIG_MIDLEMODE(DMA_IDLEMODE_NO_IDLE);
                p->dma_write(l , OCP_SYSCONFIG, 0);

                l = p->dma_read(CCR, lch);
                l &= ~OMAP_DMA_CCR_EN;
                p->dma_write(l, CCR, lch);

                /* Wait for sDMA FIFO drain */
                l = p->dma_read(CCR, lch);
                while (i < 100 && (l & (OMAP_DMA_CCR_RD_ACTIVE |
                                        OMAP_DMA_CCR_WR_ACTIVE))) {
                        udelay(5);
                        i++;
                        l = p->dma_read(CCR, lch);
                }
                if (i >= 100)
                        pr_err("DMA drain did not complete on lch %d\n", lch);
                /* Restore OCP_SYSCONFIG */
                p->dma_write(sys_cf, OCP_SYSCONFIG, lch);
        } else {
                l &= ~OMAP_DMA_CCR_EN;
                p->dma_write(l, CCR, lch);
        }

        /*
         * Ensure that data transferred by DMA is visible to any access
         * after DMA has been disabled.  This is important for coherent
         * DMA regions.
         */
        mb();

        if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1) {
                int next_lch, cur_lch = lch;
                char dma_chan_link_map[MAX_LOGICAL_DMA_CH_COUNT];

                memset(dma_chan_link_map, 0, sizeof(dma_chan_link_map));
                do {
                        /* The loop case: we've been here already */
                        if (dma_chan_link_map[cur_lch])
                                break;
                        /* Mark the current channel */
                        dma_chan_link_map[cur_lch] = 1;

                        disable_lnk(cur_lch);

                        next_lch = dma_chan[cur_lch].next_lch;
                        cur_lch = next_lch;
                } while (next_lch != -1);
        }

        dma_chan[lch].flags &= ~OMAP_DMA_ACTIVE;
}
EXPORT_SYMBOL(omap_stop_dma);

/*
 * Allows changing the DMA callback function or data. This may be needed if
 * the driver shares a single DMA channel for multiple dma triggers.
 */
int omap_set_dma_callback(int lch,
                          void (*callback)(int lch, u16 ch_status, void *data),
                          void *data)
{
        unsigned long flags;

        if (lch < 0)
                return -ENODEV;

        spin_lock_irqsave(&dma_chan_lock, flags);
        if (dma_chan[lch].dev_id == -1) {
                printk(KERN_ERR "DMA callback for not set for free channel\n");
                spin_unlock_irqrestore(&dma_chan_lock, flags);
                return -EINVAL;
        }
        dma_chan[lch].callback = callback;
        dma_chan[lch].data = data;
        spin_unlock_irqrestore(&dma_chan_lock, flags);

        return 0;
}
EXPORT_SYMBOL(omap_set_dma_callback);

/*
 * Returns current physical source address for the given DMA channel.
 * If the channel is running the caller must disable interrupts prior calling
 * this function and process the returned value before re-enabling interrupt to
 * prevent races with the interrupt handler. Note that in continuous mode there
 * is a chance for CSSA_L register overflow between the two reads resulting
 * in incorrect return value.
 */
dma_addr_t omap_get_dma_src_pos(int lch)
{
        dma_addr_t offset = 0;

        if (dma_omap15xx())
                offset = p->dma_read(CPC, lch);
        else
                offset = p->dma_read(CSAC, lch);

        if (IS_DMA_ERRATA(DMA_ERRATA_3_3) && offset == 0)
                offset = p->dma_read(CSAC, lch);

        if (!dma_omap15xx()) {
                /*
                 * CDAC == 0 indicates that the DMA transfer on the channel has
                 * not been started (no data has been transferred so far).
                 * Return the programmed source start address in this case.
                 */
                if (likely(p->dma_read(CDAC, lch)))
                        offset = p->dma_read(CSAC, lch);
                else
                        offset = p->dma_read(CSSA, lch);
        }

        if (dma_omap1())
                offset |= (p->dma_read(CSSA, lch) & 0xFFFF0000);

        return offset;
}
EXPORT_SYMBOL(omap_get_dma_src_pos);

/*
 * Returns current physical destination address for the given DMA channel.
 * If the channel is running the caller must disable interrupts prior calling
 * this function and process the returned value before re-enabling interrupt to
 * prevent races with the interrupt handler. Note that in continuous mode there
 * is a chance for CDSA_L register overflow between the two reads resulting
 * in incorrect return value.
 */
dma_addr_t omap_get_dma_dst_pos(int lch)
{
        dma_addr_t offset = 0;

        if (dma_omap15xx())
                offset = p->dma_read(CPC, lch);
        else
                offset = p->dma_read(CDAC, lch);

        /*
         * omap 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
         * read before the DMA controller finished disabling the channel.
         */
        if (!dma_omap15xx() && offset == 0) {
                offset = p->dma_read(CDAC, lch);
                /*
                 * CDAC == 0 indicates that the DMA transfer on the channel has
                 * not been started (no data has been transferred so far).
                 * Return the programmed destination start address in this case.
                 */
                if (unlikely(!offset))
                        offset = p->dma_read(CDSA, lch);
        }

        if (dma_omap1())
                offset |= (p->dma_read(CDSA, lch) & 0xFFFF0000);

        return offset;
}
EXPORT_SYMBOL(omap_get_dma_dst_pos);

int omap_get_dma_active_status(int lch)
{
        return (p->dma_read(CCR, lch) & OMAP_DMA_CCR_EN) != 0;
}
EXPORT_SYMBOL(omap_get_dma_active_status);

int omap_dma_running(void)
{
        int lch;

        if (dma_omap1())
                if (omap_lcd_dma_running())
                        return 1;

        for (lch = 0; lch < dma_chan_count; lch++)
                if (p->dma_read(CCR, lch) & OMAP_DMA_CCR_EN)
                        return 1;

        return 0;
}

/*
 * lch_queue DMA will start right after lch_head one is finished.
 * For this DMA link to start, you still need to start (see omap_start_dma)
 * the first one. That will fire up the entire queue.
 */
void omap_dma_link_lch(int lch_head, int lch_queue)
{
        if (omap_dma_in_1510_mode()) {
                if (lch_head == lch_queue) {
                        p->dma_write(p->dma_read(CCR, lch_head) | (3 << 8),
                                                                CCR, lch_head);
                        return;
                }
                printk(KERN_ERR "DMA linking is not supported in 1510 mode\n");
                BUG();
                return;
        }

        if ((dma_chan[lch_head].dev_id == -1) ||
            (dma_chan[lch_queue].dev_id == -1)) {
                pr_err("omap_dma: trying to link non requested channels\n");
                dump_stack();
        }

        dma_chan[lch_head].next_lch = lch_queue;
}
EXPORT_SYMBOL(omap_dma_link_lch);

/*
 * Once the DMA queue is stopped, we can destroy it.
 */
void omap_dma_unlink_lch(int lch_head, int lch_queue)
{
        if (omap_dma_in_1510_mode()) {
                if (lch_head == lch_queue) {
                        p->dma_write(p->dma_read(CCR, lch_head) & ~(3 << 8),
                                                                CCR, lch_head);
                        return;
                }
                printk(KERN_ERR "DMA linking is not supported in 1510 mode\n");
                BUG();
                return;
        }

        if (dma_chan[lch_head].next_lch != lch_queue ||
            dma_chan[lch_head].next_lch == -1) {
                pr_err("omap_dma: trying to unlink non linked channels\n");
                dump_stack();
        }

        if ((dma_chan[lch_head].flags & OMAP_DMA_ACTIVE) ||
            (dma_chan[lch_queue].flags & OMAP_DMA_ACTIVE)) {
                pr_err("omap_dma: You need to stop the DMA channels before unlinking\n");
                dump_stack();
        }

        dma_chan[lch_head].next_lch = -1;
}
EXPORT_SYMBOL(omap_dma_unlink_lch);

#ifndef CONFIG_ARCH_OMAP1
/* Create chain of DMA channesls */
static void create_dma_lch_chain(int lch_head, int lch_queue)
{
        u32 l;

        /* Check if this is the first link in chain */
        if (dma_chan[lch_head].next_linked_ch == -1) {
                dma_chan[lch_head].next_linked_ch = lch_queue;
                dma_chan[lch_head].prev_linked_ch = lch_queue;
                dma_chan[lch_queue].next_linked_ch = lch_head;
                dma_chan[lch_queue].prev_linked_ch = lch_head;
        }

        /* a link exists, link the new channel in circular chain */
        else {
                dma_chan[lch_queue].next_linked_ch =
                                        dma_chan[lch_head].next_linked_ch;
                dma_chan[lch_queue].prev_linked_ch = lch_head;
                dma_chan[lch_head].next_linked_ch = lch_queue;
                dma_chan[dma_chan[lch_queue].next_linked_ch].prev_linked_ch =
                                        lch_queue;
        }

        l = p->dma_read(CLNK_CTRL, lch_head);
        l &= ~(0x1f);
        l |= lch_queue;
        p->dma_write(l, CLNK_CTRL, lch_head);

        l = p->dma_read(CLNK_CTRL, lch_queue);
        l &= ~(0x1f);
        l |= (dma_chan[lch_queue].next_linked_ch);
        p->dma_write(l, CLNK_CTRL, lch_queue);
}

/**
 * @brief omap_request_dma_chain : Request a chain of DMA channels
 *
 * @param dev_id - Device id using the dma channel
 * @param dev_name - Device name
 * @param callback - Call back function
 * @chain_id -
 * @no_of_chans - Number of channels requested
 * @chain_mode - Dynamic or static chaining : OMAP_DMA_STATIC_CHAIN
 *                                            OMAP_DMA_DYNAMIC_CHAIN
 * @params - Channel parameters
 *
 * @return - Success : 0
 *           Failure: -EINVAL/-ENOMEM
 */
int omap_request_dma_chain(int dev_id, const char *dev_name,
                           void (*callback) (int lch, u16 ch_status,
                                             void *data),
                           int *chain_id, int no_of_chans, int chain_mode,
                           struct omap_dma_channel_params params)
{
        int *channels;
        int i, err;

        /* Is the chain mode valid ? */
        if (chain_mode != OMAP_DMA_STATIC_CHAIN
                        && chain_mode != OMAP_DMA_DYNAMIC_CHAIN) {
                printk(KERN_ERR "Invalid chain mode requested\n");
                return -EINVAL;
        }

        if (unlikely((no_of_chans < 1
                        || no_of_chans > dma_lch_count))) {
                printk(KERN_ERR "Invalid Number of channels requested\n");
                return -EINVAL;
        }

        /*
         * Allocate a queue to maintain the status of the channels
         * in the chain
         */
        channels = kmalloc(sizeof(*channels) * no_of_chans, GFP_KERNEL);
        if (channels == NULL) {
                printk(KERN_ERR "omap_dma: No memory for channel queue\n");
                return -ENOMEM;
        }

        /* request and reserve DMA channels for the chain */
        for (i = 0; i < no_of_chans; i++) {
                err = omap_request_dma(dev_id, dev_name,
                                        callback, NULL, &channels[i]);
                if (err < 0) {
                        int j;
                        for (j = 0; j < i; j++)
                                omap_free_dma(channels[j]);
                        kfree(channels);
                        printk(KERN_ERR "omap_dma: Request failed %d\n", err);
                        return err;
                }
                dma_chan[channels[i]].prev_linked_ch = -1;
                dma_chan[channels[i]].state = DMA_CH_NOTSTARTED;

                /*
                 * Allowing client drivers to set common parameters now,
                 * so that later only relevant (src_start, dest_start
                 * and element count) can be set
                 */
                omap_set_dma_params(channels[i], &params);
        }

        *chain_id = channels[0];
        dma_linked_lch[*chain_id].linked_dmach_q = channels;
        dma_linked_lch[*chain_id].chain_mode = chain_mode;
        dma_linked_lch[*chain_id].chain_state = DMA_CHAIN_NOTSTARTED;
        dma_linked_lch[*chain_id].no_of_lchs_linked = no_of_chans;

        for (i = 0; i < no_of_chans; i++)
                dma_chan[channels[i]].chain_id = *chain_id;

        /* Reset the Queue pointers */
        OMAP_DMA_CHAIN_QINIT(*chain_id);

        /* Set up the chain */
        if (no_of_chans == 1)
                create_dma_lch_chain(channels[0], channels[0]);
        else {
                for (i = 0; i < (no_of_chans - 1); i++)
                        create_dma_lch_chain(channels[i], channels[i + 1]);
        }

        return 0;
}
EXPORT_SYMBOL(omap_request_dma_chain);

/**
 * @brief omap_modify_dma_chain_param : Modify the chain's params - Modify the
 * params after setting it. Dont do this while dma is running!!
 *
 * @param chain_id - Chained logical channel id.
 * @param params
 *
 * @return - Success : 0
 *           Failure : -EINVAL
 */
int omap_modify_dma_chain_params(int chain_id,
                                struct omap_dma_channel_params params)
{
        int *channels;
        u32 i;

        /* Check for input params */
        if (unlikely((chain_id < 0
                        || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exists\n");
                return -EINVAL;
        }
        channels = dma_linked_lch[chain_id].linked_dmach_q;

        for (i = 0; i < dma_linked_lch[chain_id].no_of_lchs_linked; i++) {
                /*
                 * Allowing client drivers to set common parameters now,
                 * so that later only relevant (src_start, dest_start
                 * and element count) can be set
                 */
                omap_set_dma_params(channels[i], &params);
        }

        return 0;
}
EXPORT_SYMBOL(omap_modify_dma_chain_params);

/**
 * @brief omap_free_dma_chain - Free all the logical channels in a chain.
 *
 * @param chain_id
 *
 * @return - Success : 0
 *           Failure : -EINVAL
 */
int omap_free_dma_chain(int chain_id)
{
        int *channels;
        u32 i;

        /* Check for input params */
        if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exists\n");
                return -EINVAL;
        }

        channels = dma_linked_lch[chain_id].linked_dmach_q;
        for (i = 0; i < dma_linked_lch[chain_id].no_of_lchs_linked; i++) {
                dma_chan[channels[i]].next_linked_ch = -1;
                dma_chan[channels[i]].prev_linked_ch = -1;
                dma_chan[channels[i]].chain_id = -1;
                dma_chan[channels[i]].state = DMA_CH_NOTSTARTED;
                omap_free_dma(channels[i]);
        }

        kfree(channels);

        dma_linked_lch[chain_id].linked_dmach_q = NULL;
        dma_linked_lch[chain_id].chain_mode = -1;
        dma_linked_lch[chain_id].chain_state = -1;

        return (0);
}
EXPORT_SYMBOL(omap_free_dma_chain);

/**
 * @brief omap_dma_chain_status - Check if the chain is in
 * active / inactive state.
 * @param chain_id
 *
 * @return - Success : OMAP_DMA_CHAIN_ACTIVE/OMAP_DMA_CHAIN_INACTIVE
 *           Failure : -EINVAL
 */
int omap_dma_chain_status(int chain_id)
{
        /* Check for input params */
        if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exists\n");
                return -EINVAL;
        }
        pr_debug("CHAINID=%d, qcnt=%d\n", chain_id,
                        dma_linked_lch[chain_id].q_count);

        if (OMAP_DMA_CHAIN_QEMPTY(chain_id))
                return OMAP_DMA_CHAIN_INACTIVE;

        return OMAP_DMA_CHAIN_ACTIVE;
}
EXPORT_SYMBOL(omap_dma_chain_status);

/**
 * @brief omap_dma_chain_a_transfer - Get a free channel from a chain,
 * set the params and start the transfer.
 *
 * @param chain_id
 * @param src_start - buffer start address
 * @param dest_start - Dest address
 * @param elem_count
 * @param frame_count
 * @param callbk_data - channel callback parameter data.
 *
 * @return  - Success : 0
 *            Failure: -EINVAL/-EBUSY
 */
int omap_dma_chain_a_transfer(int chain_id, int src_start, int dest_start,
                        int elem_count, int frame_count, void *callbk_data)
{
        int *channels;
        u32 l, lch;
        int start_dma = 0;

        /*
         * if buffer size is less than 1 then there is
         * no use of starting the chain
         */
        if (elem_count < 1) {
                printk(KERN_ERR "Invalid buffer size\n");
                return -EINVAL;
        }

        /* Check for input params */
        if (unlikely((chain_id < 0
                        || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exist\n");
                return -EINVAL;
        }

        /* Check if all the channels in chain are in use */
        if (OMAP_DMA_CHAIN_QFULL(chain_id))
                return -EBUSY;

        /* Frame count may be negative in case of indexed transfers */
        channels = dma_linked_lch[chain_id].linked_dmach_q;

        /* Get a free channel */
        lch = channels[dma_linked_lch[chain_id].q_tail];

        /* Store the callback data */
        dma_chan[lch].data = callbk_data;

        /* Increment the q_tail */
        OMAP_DMA_CHAIN_INCQTAIL(chain_id);

        /* Set the params to the free channel */
        if (src_start != 0)
                p->dma_write(src_start, CSSA, lch);
        if (dest_start != 0)
                p->dma_write(dest_start, CDSA, lch);

        /* Write the buffer size */
        p->dma_write(elem_count, CEN, lch);
        p->dma_write(frame_count, CFN, lch);

        /*
         * If the chain is dynamically linked,
         * then we may have to start the chain if its not active
         */
        if (dma_linked_lch[chain_id].chain_mode == OMAP_DMA_DYNAMIC_CHAIN) {

                /*
                 * In Dynamic chain, if the chain is not started,
                 * queue the channel
                 */
                if (dma_linked_lch[chain_id].chain_state ==
                                                DMA_CHAIN_NOTSTARTED) {
                        /* Enable the link in previous channel */
                        if (dma_chan[dma_chan[lch].prev_linked_ch].state ==
                                                                DMA_CH_QUEUED)
                                enable_lnk(dma_chan[lch].prev_linked_ch);
                        dma_chan[lch].state = DMA_CH_QUEUED;
                }

                /*
                 * Chain is already started, make sure its active,
                 * if not then start the chain
                 */
                else {
                        start_dma = 1;

                        if (dma_chan[dma_chan[lch].prev_linked_ch].state ==
                                                        DMA_CH_STARTED) {
                                enable_lnk(dma_chan[lch].prev_linked_ch);
                                dma_chan[lch].state = DMA_CH_QUEUED;
                                start_dma = 0;
                                if (0 == ((1 << 7) & p->dma_read(
                                        CCR, dma_chan[lch].prev_linked_ch))) {
                                        disable_lnk(dma_chan[lch].
                                                    prev_linked_ch);
                                        pr_debug("\n prev ch is stopped\n");
                                        start_dma = 1;
                                }
                        }

                        else if (dma_chan[dma_chan[lch].prev_linked_ch].state
                                                        == DMA_CH_QUEUED) {
                                enable_lnk(dma_chan[lch].prev_linked_ch);
                                dma_chan[lch].state = DMA_CH_QUEUED;
                                start_dma = 0;
                        }
                        omap_enable_channel_irq(lch);

                        l = p->dma_read(CCR, lch);

                        if ((0 == (l & (1 << 24))))
                                l &= ~(1 << 25);
                        else
                                l |= (1 << 25);
                        if (start_dma == 1) {
                                if (0 == (l & (1 << 7))) {
                                        l |= (1 << 7);
                                        dma_chan[lch].state = DMA_CH_STARTED;
                                        pr_debug("starting %d\n", lch);
                                        p->dma_write(l, CCR, lch);
                                } else
                                        start_dma = 0;
                        } else {
                                if (0 == (l & (1 << 7)))
                                        p->dma_write(l, CCR, lch);
                        }
                        dma_chan[lch].flags |= OMAP_DMA_ACTIVE;
                }
        }

        return 0;
}
EXPORT_SYMBOL(omap_dma_chain_a_transfer);

/**
 * @brief omap_start_dma_chain_transfers - Start the chain
 *
 * @param chain_id
 *
 * @return - Success : 0
 *           Failure : -EINVAL/-EBUSY
 */
int omap_start_dma_chain_transfers(int chain_id)
{
        int *channels;
        u32 l, i;

        if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        channels = dma_linked_lch[chain_id].linked_dmach_q;

        if (dma_linked_lch[channels[0]].chain_state == DMA_CHAIN_STARTED) {
                printk(KERN_ERR "Chain is already started\n");
                return -EBUSY;
        }

        if (dma_linked_lch[chain_id].chain_mode == OMAP_DMA_STATIC_CHAIN) {
                for (i = 0; i < dma_linked_lch[chain_id].no_of_lchs_linked;
                                                                        i++) {
                        enable_lnk(channels[i]);
                        omap_enable_channel_irq(channels[i]);
                }
        } else {
                omap_enable_channel_irq(channels[0]);
        }

        l = p->dma_read(CCR, channels[0]);
        l |= (1 << 7);
        dma_linked_lch[chain_id].chain_state = DMA_CHAIN_STARTED;
        dma_chan[channels[0]].state = DMA_CH_STARTED;

        if ((0 == (l & (1 << 24))))
                l &= ~(1 << 25);
        else
                l |= (1 << 25);
        p->dma_write(l, CCR, channels[0]);

        dma_chan[channels[0]].flags |= OMAP_DMA_ACTIVE;

        return 0;
}
EXPORT_SYMBOL(omap_start_dma_chain_transfers);

/**
 * @brief omap_stop_dma_chain_transfers - Stop the dma transfer of a chain.
 *
 * @param chain_id
 *
 * @return - Success : 0
 *           Failure : EINVAL
 */
int omap_stop_dma_chain_transfers(int chain_id)
{
        int *channels;
        u32 l, i;
        u32 sys_cf = 0;

        /* Check for input params */
        if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exists\n");
                return -EINVAL;
        }
        channels = dma_linked_lch[chain_id].linked_dmach_q;

        if (IS_DMA_ERRATA(DMA_ERRATA_i88)) {
                sys_cf = p->dma_read(OCP_SYSCONFIG, 0);
                l = sys_cf;
                /* Middle mode reg set no Standby */
                l &= ~((1 << 12)|(1 << 13));
                p->dma_write(l, OCP_SYSCONFIG, 0);
        }

        for (i = 0; i < dma_linked_lch[chain_id].no_of_lchs_linked; i++) {

                /* Stop the Channel transmission */
                l = p->dma_read(CCR, channels[i]);
                l &= ~(1 << 7);
                p->dma_write(l, CCR, channels[i]);

                /* Disable the link in all the channels */
                disable_lnk(channels[i]);
                dma_chan[channels[i]].state = DMA_CH_NOTSTARTED;

        }
        dma_linked_lch[chain_id].chain_state = DMA_CHAIN_NOTSTARTED;

        /* Reset the Queue pointers */
        OMAP_DMA_CHAIN_QINIT(chain_id);

        if (IS_DMA_ERRATA(DMA_ERRATA_i88))
                p->dma_write(sys_cf, OCP_SYSCONFIG, 0);

        return 0;
}
EXPORT_SYMBOL(omap_stop_dma_chain_transfers);

/* Get the index of the ongoing DMA in chain */
/**
 * @brief omap_get_dma_chain_index - Get the element and frame index
 * of the ongoing DMA in chain
 *
 * @param chain_id
 * @param ei - Element index
 * @param fi - Frame index
 *
 * @return - Success : 0
 *           Failure : -EINVAL
 */
int omap_get_dma_chain_index(int chain_id, int *ei, int *fi)
{
        int lch;
        int *channels;

        /* Check for input params */
        if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exists\n");
                return -EINVAL;
        }
        if ((!ei) || (!fi))
                return -EINVAL;

        channels = dma_linked_lch[chain_id].linked_dmach_q;

        /* Get the current channel */
        lch = channels[dma_linked_lch[chain_id].q_head];

        *ei = p->dma_read(CCEN, lch);
        *fi = p->dma_read(CCFN, lch);

        return 0;
}
EXPORT_SYMBOL(omap_get_dma_chain_index);

/**
 * @brief omap_get_dma_chain_dst_pos - Get the destination position of the
 * ongoing DMA in chain
 *
 * @param chain_id
 *
 * @return - Success : Destination position
 *           Failure : -EINVAL
 */
int omap_get_dma_chain_dst_pos(int chain_id)
{
        int lch;
        int *channels;

        /* Check for input params */
        if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exists\n");
                return -EINVAL;
        }

        channels = dma_linked_lch[chain_id].linked_dmach_q;

        /* Get the current channel */
        lch = channels[dma_linked_lch[chain_id].q_head];

        return p->dma_read(CDAC, lch);
}
EXPORT_SYMBOL(omap_get_dma_chain_dst_pos);

/**
 * @brief omap_get_dma_chain_src_pos - Get the source position
 * of the ongoing DMA in chain
 * @param chain_id
 *
 * @return - Success : Destination position
 *           Failure : -EINVAL
 */
int omap_get_dma_chain_src_pos(int chain_id)
{
        int lch;
        int *channels;

        /* Check for input params */
        if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
                printk(KERN_ERR "Invalid chain id\n");
                return -EINVAL;
        }

        /* Check if the chain exists */
        if (dma_linked_lch[chain_id].linked_dmach_q == NULL) {
                printk(KERN_ERR "Chain doesn't exists\n");
                return -EINVAL;
        }

        channels = dma_linked_lch[chain_id].linked_dmach_q;

        /* Get the current channel */
        lch = channels[dma_linked_lch[chain_id].q_head];

        return p->dma_read(CSAC, lch);
}
EXPORT_SYMBOL(omap_get_dma_chain_src_pos);
#endif  /* ifndef CONFIG_ARCH_OMAP1 */

/*----------------------------------------------------------------------------*/

#ifdef CONFIG_ARCH_OMAP1

static int omap1_dma_handle_ch(int ch)
{
        u32 csr;

        if (enable_1510_mode && ch >= 6) {
                csr = dma_chan[ch].saved_csr;
                dma_chan[ch].saved_csr = 0;
        } else
                csr = p->dma_read(CSR, ch);
        if (enable_1510_mode && ch <= 2 && (csr >> 7) != 0) {
                dma_chan[ch + 6].saved_csr = csr >> 7;
                csr &= 0x7f;
        }
        if ((csr & 0x3f) == 0)
                return 0;
        if (unlikely(dma_chan[ch].dev_id == -1)) {
                pr_warn("Spurious interrupt from DMA channel %d (CSR %04x)\n",
                        ch, csr);
                return 0;
        }
        if (unlikely(csr & OMAP1_DMA_TOUT_IRQ))
                pr_warn("DMA timeout with device %d\n", dma_chan[ch].dev_id);
        if (unlikely(csr & OMAP_DMA_DROP_IRQ))
                pr_warn("DMA synchronization event drop occurred with device %d\n",
                        dma_chan[ch].dev_id);
        if (likely(csr & OMAP_DMA_BLOCK_IRQ))
                dma_chan[ch].flags &= ~OMAP_DMA_ACTIVE;
        if (likely(dma_chan[ch].callback != NULL))
                dma_chan[ch].callback(ch, csr, dma_chan[ch].data);

        return 1;
}

static irqreturn_t omap1_dma_irq_handler(int irq, void *dev_id)
{
        int ch = ((int) dev_id) - 1;
        int handled = 0;

        for (;;) {
                int handled_now = 0;

                handled_now += omap1_dma_handle_ch(ch);
                if (enable_1510_mode && dma_chan[ch + 6].saved_csr)
                        handled_now += omap1_dma_handle_ch(ch + 6);
                if (!handled_now)
                        break;
                handled += handled_now;
        }

        return handled ? IRQ_HANDLED : IRQ_NONE;
}

#else
#define omap1_dma_irq_handler   NULL
#endif

#ifdef CONFIG_ARCH_OMAP2PLUS

static int omap2_dma_handle_ch(int ch)
{
        u32 status = p->dma_read(CSR, ch);

        if (!status) {
                if (printk_ratelimit())
                        pr_warn("Spurious DMA IRQ for lch %d\n", ch);
                p->dma_write(1 << ch, IRQSTATUS_L0, ch);
                return 0;
        }
        if (unlikely(dma_chan[ch].dev_id == -1)) {
                if (printk_ratelimit())
                        pr_warn("IRQ %04x for non-allocated DMA channel %d\n",
                                status, ch);
                return 0;
        }
        if (unlikely(status & OMAP_DMA_DROP_IRQ))
                pr_info("DMA synchronization event drop occurred with device %d\n",
                        dma_chan[ch].dev_id);
        if (unlikely(status & OMAP2_DMA_TRANS_ERR_IRQ)) {
                printk(KERN_INFO "DMA transaction error with device %d\n",
                       dma_chan[ch].dev_id);
                if (IS_DMA_ERRATA(DMA_ERRATA_i378)) {
                        u32 ccr;

                        ccr = p->dma_read(CCR, ch);
                        ccr &= ~OMAP_DMA_CCR_EN;
                        p->dma_write(ccr, CCR, ch);
                        dma_chan[ch].flags &= ~OMAP_DMA_ACTIVE;
                }
        }
        if (unlikely(status & OMAP2_DMA_SECURE_ERR_IRQ))
                printk(KERN_INFO "DMA secure error with device %d\n",
                       dma_chan[ch].dev_id);
        if (unlikely(status & OMAP2_DMA_MISALIGNED_ERR_IRQ))
                printk(KERN_INFO "DMA misaligned error with device %d\n",
                       dma_chan[ch].dev_id);

        p->dma_write(status, CSR, ch);
        p->dma_write(1 << ch, IRQSTATUS_L0, ch);
        /* read back the register to flush the write */
        p->dma_read(IRQSTATUS_L0, ch);

        /* If the ch is not chained then chain_id will be -1 */
        if (dma_chan[ch].chain_id != -1) {
                int chain_id = dma_chan[ch].chain_id;
                dma_chan[ch].state = DMA_CH_NOTSTARTED;
                if (p->dma_read(CLNK_CTRL, ch) & (1 << 15))
                        dma_chan[dma_chan[ch].next_linked_ch].state =
                                                        DMA_CH_STARTED;
                if (dma_linked_lch[chain_id].chain_mode ==
                                                OMAP_DMA_DYNAMIC_CHAIN)
                        disable_lnk(ch);

                if (!OMAP_DMA_CHAIN_QEMPTY(chain_id))
                        OMAP_DMA_CHAIN_INCQHEAD(chain_id);

                status = p->dma_read(CSR, ch);
                p->dma_write(status, CSR, ch);
        }

        if (likely(dma_chan[ch].callback != NULL))
                dma_chan[ch].callback(ch, status, dma_chan[ch].data);

        return 0;
}

/* STATUS register count is from 1-32 while our is 0-31 */
static irqreturn_t omap2_dma_irq_handler(int irq, void *dev_id)
{
        u32 val, enable_reg;
        int i;

        val = p->dma_read(IRQSTATUS_L0, 0);
        if (val == 0) {
                if (printk_ratelimit())
                        printk(KERN_WARNING "Spurious DMA IRQ\n");
                return IRQ_HANDLED;
        }
        enable_reg = p->dma_read(IRQENABLE_L0, 0);
        val &= enable_reg; /* Dispatch only relevant interrupts */
        for (i = 0; i < dma_lch_count && val != 0; i++) {
                if (val & 1)
                        omap2_dma_handle_ch(i);
                val >>= 1;
        }

        return IRQ_HANDLED;
}

static struct irqaction omap24xx_dma_irq = {
        .name = "DMA",
        .handler = omap2_dma_irq_handler,
        .flags = IRQF_DISABLED
};

#else
static struct irqaction omap24xx_dma_irq;
#endif

/*----------------------------------------------------------------------------*/

void omap_dma_global_context_save(void)
{
        omap_dma_global_context.dma_irqenable_l0 =
                p->dma_read(IRQENABLE_L0, 0);
        omap_dma_global_context.dma_ocp_sysconfig =
                p->dma_read(OCP_SYSCONFIG, 0);
        omap_dma_global_context.dma_gcr = p->dma_read(GCR, 0);
}

void omap_dma_global_context_restore(void)
{
        int ch;

        p->dma_write(omap_dma_global_context.dma_gcr, GCR, 0);
        p->dma_write(omap_dma_global_context.dma_ocp_sysconfig,
                OCP_SYSCONFIG, 0);
        p->dma_write(omap_dma_global_context.dma_irqenable_l0,
                IRQENABLE_L0, 0);

        if (IS_DMA_ERRATA(DMA_ROMCODE_BUG))
                p->dma_write(0x3 , IRQSTATUS_L0, 0);

        for (ch = 0; ch < dma_chan_count; ch++)
                if (dma_chan[ch].dev_id != -1)

                        omap_clear_dma(ch);
}

static int omap_system_dma_probe(struct platform_device *pdev)
{
        int ch, ret = 0;
        int dma_irq;
        char irq_name[4];
        int irq_rel;

        p = pdev->dev.platform_data;
        if (!p) {
                dev_err(&pdev->dev,
                        "%s: System DMA initialized without platform data\n",
                        __func__);
                return -EINVAL;
        }

        d                       = p->dma_attr;
        errata                  = p->errata;

        if ((d->dev_caps & RESERVE_CHANNEL) && omap_dma_reserve_channels
                        && (omap_dma_reserve_channels < d->lch_count))
                d->lch_count    = omap_dma_reserve_channels;

        dma_lch_count           = d->lch_count;
        dma_chan_count          = dma_lch_count;
        dma_chan                = d->chan;
        enable_1510_mode        = d->dev_caps & ENABLE_1510_MODE;

        if (dma_omap2plus()) {
                dma_linked_lch = kzalloc(sizeof(struct dma_link_info) *
                                                dma_lch_count, GFP_KERNEL);
                if (!dma_linked_lch) {
                        ret = -ENOMEM;
                        goto exit_dma_lch_fail;
                }
        }

        spin_lock_init(&dma_chan_lock);
        for (ch = 0; ch < dma_chan_count; ch++) {
                omap_clear_dma(ch);
                if (dma_omap2plus())
                        omap2_disable_irq_lch(ch);

                dma_chan[ch].dev_id = -1;
                dma_chan[ch].next_lch = -1;

                if (ch >= 6 && enable_1510_mode)
                        continue;

                if (dma_omap1()) {
                        /*
                         * request_irq() doesn't like dev_id (ie. ch) being
                         * zero, so we have to kludge around this.
                         */
                        sprintf(&irq_name[0], "%d", ch);
                        dma_irq = platform_get_irq_byname(pdev, irq_name);

                        if (dma_irq < 0) {
                                ret = dma_irq;
                                goto exit_dma_irq_fail;
                        }

                        /* INT_DMA_LCD is handled in lcd_dma.c */
                        if (dma_irq == INT_DMA_LCD)
                                continue;

                        ret = request_irq(dma_irq,
                                        omap1_dma_irq_handler, 0, "DMA",
                                        (void *) (ch + 1));
                        if (ret != 0)
                                goto exit_dma_irq_fail;
                }
        }

        if (d->dev_caps & IS_RW_PRIORITY)
                omap_dma_set_global_params(DMA_DEFAULT_ARB_RATE,
                                DMA_DEFAULT_FIFO_DEPTH, 0);

        if (dma_omap2plus()) {
                strcpy(irq_name, "0");
                dma_irq = platform_get_irq_byname(pdev, irq_name);
                if (dma_irq < 0) {
                        dev_err(&pdev->dev, "failed: request IRQ %d", dma_irq);
                        ret = dma_irq;
                        goto exit_dma_lch_fail;
                }
                ret = setup_irq(dma_irq, &omap24xx_dma_irq);
                if (ret) {
                        dev_err(&pdev->dev, "set_up failed for IRQ %d for DMA (error %d)\n",
                                dma_irq, ret);
                        goto exit_dma_lch_fail;
                }
        }

        /* reserve dma channels 0 and 1 in high security devices on 34xx */
        if (d->dev_caps & HS_CHANNELS_RESERVED) {
                pr_info("Reserving DMA channels 0 and 1 for HS ROM code\n");
                dma_chan[0].dev_id = 0;
                dma_chan[1].dev_id = 1;
        }
        p->show_dma_caps();
        return 0;

exit_dma_irq_fail:
        dev_err(&pdev->dev, "unable to request IRQ %d for DMA (error %d)\n",
                dma_irq, ret);
        for (irq_rel = 0; irq_rel < ch; irq_rel++) {
                dma_irq = platform_get_irq(pdev, irq_rel);
                free_irq(dma_irq, (void *)(irq_rel + 1));
        }

exit_dma_lch_fail:
        kfree(dma_chan);
        return ret;
}

static int omap_system_dma_remove(struct platform_device *pdev)
{
        int dma_irq;

        if (dma_omap2plus()) {
                char irq_name[4];
                strcpy(irq_name, "0");
                dma_irq = platform_get_irq_byname(pdev, irq_name);
                remove_irq(dma_irq, &omap24xx_dma_irq);
        } else {
                int irq_rel = 0;
                for ( ; irq_rel < dma_chan_count; irq_rel++) {
                        dma_irq = platform_get_irq(pdev, irq_rel);
                        free_irq(dma_irq, (void *)(irq_rel + 1));
                }
        }
        kfree(dma_chan);
        return 0;
}

static struct platform_driver omap_system_dma_driver = {
        .probe          = omap_system_dma_probe,
        .remove         = omap_system_dma_remove,
        .driver         = {
                .name   = "omap_dma_system"
        },
};

static int __init omap_system_dma_init(void)
{
        return platform_driver_register(&omap_system_dma_driver);
}
arch_initcall(omap_system_dma_init);

static void __exit omap_system_dma_exit(void)
{
        platform_driver_unregister(&omap_system_dma_driver);
}

MODULE_DESCRIPTION("OMAP SYSTEM DMA DRIVER");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRIVER_NAME);
MODULE_AUTHOR("Texas Instruments Inc");

/*
 * Reserve the omap SDMA channels using cmdline bootarg
 * "omap_dma_reserve_ch=". The valid range is 1 to 32
 */
static int __init omap_dma_cmdline_reserve_ch(char *str)
{
        if (get_option(&str, &omap_dma_reserve_channels) != 1)
                omap_dma_reserve_channels = 0;
        return 1;
}

__setup("omap_dma_reserve_ch=", omap_dma_cmdline_reserve_ch);