Cleaned up AMD Au1200 IDE driver:

[mirror_ubuntu-artful-kernel.git] / arch / mips / au1000 / common / dbdma.c

/*
 *
 * BRIEF MODULE DESCRIPTION
 *      The Descriptor Based DMA channel manager that first appeared
 *      on the Au1550.  I started with dma.c, but I think all that is
 *      left is this initial comment :-)
 *
 * Copyright 2004 Embedded Edge, LLC
 *      dan@embeddededge.com
 *
 *  This program is free software; you can redistribute  it and/or modify it
 *  under  the terms of  the GNU General  Public License as published by the
 *  Free Software Foundation;  either version 2 of the  License, or (at your
 *  option) any later version.
 *
 *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
 *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
 *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
 *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *  You should have received a copy of the  GNU General Public License along
 *  with this program; if not, write  to the Free Software Foundation, Inc.,
 *  675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <asm/mach-au1x00/au1000.h>
#include <asm/mach-au1x00/au1xxx_dbdma.h>
#include <asm/system.h>


#if defined(CONFIG_SOC_AU1550) || defined(CONFIG_SOC_AU1200)

/*
 * The Descriptor Based DMA supports up to 16 channels.
 *
 * There are 32 devices defined. We keep an internal structure
 * of devices using these channels, along with additional
 * information.
 *
 * We allocate the descriptors and allow access to them through various
 * functions.  The drivers allocate the data buffers and assign them
 * to the descriptors.
 */
static spinlock_t au1xxx_dbdma_spin_lock = SPIN_LOCK_UNLOCKED;

/* I couldn't find a macro that did this......
*/
#define ALIGN_ADDR(x, a)        ((((u32)(x)) + (a-1)) & ~(a-1))

static dbdma_global_t *dbdma_gptr = (dbdma_global_t *)DDMA_GLOBAL_BASE;
static int dbdma_initialized=0;
static void au1xxx_dbdma_init(void);

static dbdev_tab_t dbdev_tab[] = {
#ifdef CONFIG_SOC_AU1550
        /* UARTS */
        { DSCR_CMD0_UART0_TX, DEV_FLAGS_OUT, 0, 8, 0x11100004, 0, 0 },
        { DSCR_CMD0_UART0_RX, DEV_FLAGS_IN, 0, 8, 0x11100000, 0, 0 },
        { DSCR_CMD0_UART3_TX, DEV_FLAGS_OUT, 0, 8, 0x11400004, 0, 0 },
        { DSCR_CMD0_UART3_RX, DEV_FLAGS_IN, 0, 8, 0x11400000, 0, 0 },

        /* EXT DMA */
        { DSCR_CMD0_DMA_REQ0, 0, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_DMA_REQ1, 0, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_DMA_REQ2, 0, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_DMA_REQ3, 0, 0, 0, 0x00000000, 0, 0 },

        /* USB DEV */
        { DSCR_CMD0_USBDEV_RX0, DEV_FLAGS_IN, 4, 8, 0x10200000, 0, 0 },
        { DSCR_CMD0_USBDEV_TX0, DEV_FLAGS_OUT, 4, 8, 0x10200004, 0, 0 },
        { DSCR_CMD0_USBDEV_TX1, DEV_FLAGS_OUT, 4, 8, 0x10200008, 0, 0 },
        { DSCR_CMD0_USBDEV_TX2, DEV_FLAGS_OUT, 4, 8, 0x1020000c, 0, 0 },
        { DSCR_CMD0_USBDEV_RX3, DEV_FLAGS_IN, 4, 8, 0x10200010, 0, 0 },
        { DSCR_CMD0_USBDEV_RX4, DEV_FLAGS_IN, 4, 8, 0x10200014, 0, 0 },

        /* PSC 0 */
        { DSCR_CMD0_PSC0_TX, DEV_FLAGS_OUT, 0, 0, 0x11a0001c, 0, 0 },
        { DSCR_CMD0_PSC0_RX, DEV_FLAGS_IN, 0, 0, 0x11a0001c, 0, 0 },

        /* PSC 1 */
        { DSCR_CMD0_PSC1_TX, DEV_FLAGS_OUT, 0, 0, 0x11b0001c, 0, 0 },
        { DSCR_CMD0_PSC1_RX, DEV_FLAGS_IN, 0, 0, 0x11b0001c, 0, 0 },

        /* PSC 2 */
        { DSCR_CMD0_PSC2_TX, DEV_FLAGS_OUT, 0, 0, 0x10a0001c, 0, 0 },
        { DSCR_CMD0_PSC2_RX, DEV_FLAGS_IN, 0, 0, 0x10a0001c, 0, 0 },

        /* PSC 3 */
        { DSCR_CMD0_PSC3_TX, DEV_FLAGS_OUT, 0, 0, 0x10b0001c, 0, 0 },
        { DSCR_CMD0_PSC3_RX, DEV_FLAGS_IN, 0, 0, 0x10b0001c, 0, 0 },

        { DSCR_CMD0_PCI_WRITE, 0, 0, 0, 0x00000000, 0, 0 },     /* PCI */
        { DSCR_CMD0_NAND_FLASH, 0, 0, 0, 0x00000000, 0, 0 },    /* NAND */

        /* MAC 0 */
        { DSCR_CMD0_MAC0_RX, DEV_FLAGS_IN, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_MAC0_TX, DEV_FLAGS_OUT, 0, 0, 0x00000000, 0, 0 },

        /* MAC 1 */
        { DSCR_CMD0_MAC1_RX, DEV_FLAGS_IN, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_MAC1_TX, DEV_FLAGS_OUT, 0, 0, 0x00000000, 0, 0 },

#endif /* CONFIG_SOC_AU1550 */

#ifdef CONFIG_SOC_AU1200
        { DSCR_CMD0_UART0_TX, DEV_FLAGS_OUT, 0, 8, 0x11100004, 0, 0 },
        { DSCR_CMD0_UART0_RX, DEV_FLAGS_IN, 0, 8, 0x11100000, 0, 0 },
        { DSCR_CMD0_UART1_TX, DEV_FLAGS_OUT, 0, 8, 0x11200004, 0, 0 },
        { DSCR_CMD0_UART1_RX, DEV_FLAGS_IN, 0, 8, 0x11200000, 0, 0 },

        { DSCR_CMD0_DMA_REQ0, 0, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_DMA_REQ1, 0, 0, 0, 0x00000000, 0, 0 },

        { DSCR_CMD0_MAE_BE, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_MAE_FE, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_MAE_BOTH, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_LCD, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },

        { DSCR_CMD0_SDMS_TX0, DEV_FLAGS_OUT, 4, 8, 0x10600000, 0, 0 },
        { DSCR_CMD0_SDMS_RX0, DEV_FLAGS_IN, 4, 8, 0x10600004, 0, 0 },
        { DSCR_CMD0_SDMS_TX1, DEV_FLAGS_OUT, 4, 8, 0x10680000, 0, 0 },
        { DSCR_CMD0_SDMS_RX1, DEV_FLAGS_IN, 4, 8, 0x10680004, 0, 0 },

        { DSCR_CMD0_AES_RX, DEV_FLAGS_IN , 4, 32, 0x10300008, 0, 0 },
        { DSCR_CMD0_AES_TX, DEV_FLAGS_OUT, 4, 32, 0x10300004, 0, 0 },

        { DSCR_CMD0_PSC0_TX, DEV_FLAGS_OUT, 0, 0, 0x11a0001c, 0, 0 },
        { DSCR_CMD0_PSC0_RX, DEV_FLAGS_IN, 0, 0, 0x11a0001c, 0, 0 },
        { DSCR_CMD0_PSC0_SYNC, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },

        { DSCR_CMD0_PSC1_TX, DEV_FLAGS_OUT, 0, 0, 0x11b0001c, 0, 0 },
        { DSCR_CMD0_PSC1_RX, DEV_FLAGS_IN, 0, 0, 0x11b0001c, 0, 0 },
        { DSCR_CMD0_PSC1_SYNC, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },

        { DSCR_CMD0_CIM_RXA, DEV_FLAGS_IN, 0, 32, 0x14004020, 0, 0 },
        { DSCR_CMD0_CIM_RXB, DEV_FLAGS_IN, 0, 32, 0x14004040, 0, 0 },
        { DSCR_CMD0_CIM_RXC, DEV_FLAGS_IN, 0, 32, 0x14004060, 0, 0 },
        { DSCR_CMD0_CIM_SYNC, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },

        { DSCR_CMD0_NAND_FLASH, DEV_FLAGS_IN, 0, 0, 0x00000000, 0, 0 },

#endif // CONFIG_SOC_AU1200

        { DSCR_CMD0_THROTTLE, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },
        { DSCR_CMD0_ALWAYS, DEV_FLAGS_ANYUSE, 0, 0, 0x00000000, 0, 0 },

        /* Provide 16 user definable device types */
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
        { 0, 0, 0, 0, 0, 0, 0 },
};

#define DBDEV_TAB_SIZE (sizeof(dbdev_tab) / sizeof(dbdev_tab_t))

static chan_tab_t *chan_tab_ptr[NUM_DBDMA_CHANS];

static dbdev_tab_t *
find_dbdev_id (u32 id)
{
        int i;
        dbdev_tab_t *p;
        for (i = 0; i < DBDEV_TAB_SIZE; ++i) {
                p = &dbdev_tab[i];
                if (p->dev_id == id)
                        return p;
        }
        return NULL;
}

void * au1xxx_ddma_get_nextptr_virt(au1x_ddma_desc_t *dp)
{
        return phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));
}
EXPORT_SYMBOL(au1xxx_ddma_get_nextptr_virt);

u32
au1xxx_ddma_add_device(dbdev_tab_t *dev)
{
        u32 ret = 0;
        dbdev_tab_t *p=NULL;
        static u16 new_id=0x1000;

        p = find_dbdev_id(0);
        if ( NULL != p )
        {
                memcpy(p, dev, sizeof(dbdev_tab_t));
                p->dev_id = DSCR_DEV2CUSTOM_ID(new_id,dev->dev_id);
                ret = p->dev_id;
                new_id++;
#if 0
                printk("add_device: id:%x flags:%x padd:%x\n",
                                p->dev_id, p->dev_flags, p->dev_physaddr );
#endif
        }

        return ret;
}
EXPORT_SYMBOL(au1xxx_ddma_add_device);

/* Allocate a channel and return a non-zero descriptor if successful.
*/
u32
au1xxx_dbdma_chan_alloc(u32 srcid, u32 destid,
       void (*callback)(int, void *, struct pt_regs *), void *callparam)
{
        unsigned long   flags;
        u32             used, chan, rv;
        u32             dcp;
        int             i;
        dbdev_tab_t     *stp, *dtp;
        chan_tab_t      *ctp;
        au1x_dma_chan_t *cp;

        /* We do the intialization on the first channel allocation.
         * We have to wait because of the interrupt handler initialization
         * which can't be done successfully during board set up.
         */
        if (!dbdma_initialized)
                au1xxx_dbdma_init();
        dbdma_initialized = 1;

        if ((stp = find_dbdev_id(srcid)) == NULL) return 0;
        if ((dtp = find_dbdev_id(destid)) == NULL) return 0;

        used = 0;
        rv = 0;

        /* Check to see if we can get both channels.
        */
        spin_lock_irqsave(&au1xxx_dbdma_spin_lock, flags);
        if (!(stp->dev_flags & DEV_FLAGS_INUSE) ||
             (stp->dev_flags & DEV_FLAGS_ANYUSE)) {
                /* Got source */
                stp->dev_flags |= DEV_FLAGS_INUSE;
                if (!(dtp->dev_flags & DEV_FLAGS_INUSE) ||
                     (dtp->dev_flags & DEV_FLAGS_ANYUSE)) {
                        /* Got destination */
                        dtp->dev_flags |= DEV_FLAGS_INUSE;
                }
                else {
                        /* Can't get dest.  Release src.
                        */
                        stp->dev_flags &= ~DEV_FLAGS_INUSE;
                        used++;
                }
        }
        else {
                used++;
        }
        spin_unlock_irqrestore(&au1xxx_dbdma_spin_lock, flags);

        if (!used) {
                /* Let's see if we can allocate a channel for it.
                */
                ctp = NULL;
                chan = 0;
                spin_lock_irqsave(&au1xxx_dbdma_spin_lock, flags);
                for (i=0; i<NUM_DBDMA_CHANS; i++) {
                        if (chan_tab_ptr[i] == NULL) {
                                /* If kmalloc fails, it is caught below same
                                 * as a channel not available.
                                 */
                                ctp = (chan_tab_t *)
                                        kmalloc(sizeof(chan_tab_t), GFP_KERNEL);
                                chan_tab_ptr[i] = ctp;
                                break;
                        }
                }
                spin_unlock_irqrestore(&au1xxx_dbdma_spin_lock, flags);

                if (ctp != NULL) {
                        memset(ctp, 0, sizeof(chan_tab_t));
                        ctp->chan_index = chan = i;
                        dcp = DDMA_CHANNEL_BASE;
                        dcp += (0x0100 * chan);
                        ctp->chan_ptr = (au1x_dma_chan_t *)dcp;
                        cp = (au1x_dma_chan_t *)dcp;
                        ctp->chan_src = stp;
                        ctp->chan_dest = dtp;
                        ctp->chan_callback = callback;
                        ctp->chan_callparam = callparam;

                        /* Initialize channel configuration.
                        */
                        i = 0;
                        if (stp->dev_intlevel)
                                i |= DDMA_CFG_SED;
                        if (stp->dev_intpolarity)
                                i |= DDMA_CFG_SP;
                        if (dtp->dev_intlevel)
                                i |= DDMA_CFG_DED;
                        if (dtp->dev_intpolarity)
                                i |= DDMA_CFG_DP;
                        if ((stp->dev_flags & DEV_FLAGS_SYNC) ||
                                (dtp->dev_flags & DEV_FLAGS_SYNC))
                                        i |= DDMA_CFG_SYNC;
                        cp->ddma_cfg = i;
                        au_sync();

                        /* Return a non-zero value that can be used to
                         * find the channel information in subsequent
                         * operations.
                         */
                        rv = (u32)(&chan_tab_ptr[chan]);
                }
                else {
                        /* Release devices */
                        stp->dev_flags &= ~DEV_FLAGS_INUSE;
                        dtp->dev_flags &= ~DEV_FLAGS_INUSE;
                }
        }
        return rv;
}
EXPORT_SYMBOL(au1xxx_dbdma_chan_alloc);

/* Set the device width if source or destination is a FIFO.
 * Should be 8, 16, or 32 bits.
 */
u32
au1xxx_dbdma_set_devwidth(u32 chanid, int bits)
{
        u32             rv;
        chan_tab_t      *ctp;
        dbdev_tab_t     *stp, *dtp;

        ctp = *((chan_tab_t **)chanid);
        stp = ctp->chan_src;
        dtp = ctp->chan_dest;
        rv = 0;

        if (stp->dev_flags & DEV_FLAGS_IN) {    /* Source in fifo */
                rv = stp->dev_devwidth;
                stp->dev_devwidth = bits;
        }
        if (dtp->dev_flags & DEV_FLAGS_OUT) {   /* Destination out fifo */
                rv = dtp->dev_devwidth;
                dtp->dev_devwidth = bits;
        }

        return rv;
}
EXPORT_SYMBOL(au1xxx_dbdma_set_devwidth);

/* Allocate a descriptor ring, initializing as much as possible.
*/
u32
au1xxx_dbdma_ring_alloc(u32 chanid, int entries)
{
        int                     i;
        u32                     desc_base, srcid, destid;
        u32                     cmd0, cmd1, src1, dest1;
        u32                     src0, dest0;
        chan_tab_t              *ctp;
        dbdev_tab_t             *stp, *dtp;
        au1x_ddma_desc_t        *dp;

        /* I guess we could check this to be within the
         * range of the table......
         */
        ctp = *((chan_tab_t **)chanid);
        stp = ctp->chan_src;
        dtp = ctp->chan_dest;

        /* The descriptors must be 32-byte aligned.  There is a
         * possibility the allocation will give us such an address,
         * and if we try that first we are likely to not waste larger
         * slabs of memory.
         */
        desc_base = (u32)kmalloc(entries * sizeof(au1x_ddma_desc_t),
                        GFP_KERNEL|GFP_DMA);
        if (desc_base == 0)
                return 0;

        if (desc_base & 0x1f) {
                /* Lost....do it again, allocate extra, and round
                 * the address base.
                 */
                kfree((const void *)desc_base);
                i = entries * sizeof(au1x_ddma_desc_t);
                i += (sizeof(au1x_ddma_desc_t) - 1);
                if ((desc_base = (u32)kmalloc(i, GFP_KERNEL|GFP_DMA)) == 0)
                        return 0;

                desc_base = ALIGN_ADDR(desc_base, sizeof(au1x_ddma_desc_t));
        }
        dp = (au1x_ddma_desc_t *)desc_base;

        /* Keep track of the base descriptor.
        */
        ctp->chan_desc_base = dp;

        /* Initialize the rings with as much information as we know.
         */
        srcid = stp->dev_id;
        destid = dtp->dev_id;

        cmd0 = cmd1 = src1 = dest1 = 0;
        src0 = dest0 = 0;

        cmd0 |= DSCR_CMD0_SID(srcid);
        cmd0 |= DSCR_CMD0_DID(destid);
        cmd0 |= DSCR_CMD0_IE | DSCR_CMD0_CV;
        cmd0 |= DSCR_CMD0_ST(DSCR_CMD0_ST_CURRENT);

        switch (stp->dev_devwidth) {
        case 8:
                cmd0 |= DSCR_CMD0_SW(DSCR_CMD0_BYTE);
                break;
        case 16:
                cmd0 |= DSCR_CMD0_SW(DSCR_CMD0_HALFWORD);
                break;
        case 32:
        default:
                cmd0 |= DSCR_CMD0_SW(DSCR_CMD0_WORD);
                break;
        }

        switch (dtp->dev_devwidth) {
        case 8:
                cmd0 |= DSCR_CMD0_DW(DSCR_CMD0_BYTE);
                break;
        case 16:
                cmd0 |= DSCR_CMD0_DW(DSCR_CMD0_HALFWORD);
                break;
        case 32:
        default:
                cmd0 |= DSCR_CMD0_DW(DSCR_CMD0_WORD);
                break;
        }

        /* If the device is marked as an in/out FIFO, ensure it is
         * set non-coherent.
         */
        if (stp->dev_flags & DEV_FLAGS_IN)
                cmd0 |= DSCR_CMD0_SN;           /* Source in fifo */
        if (dtp->dev_flags & DEV_FLAGS_OUT)
                cmd0 |= DSCR_CMD0_DN;           /* Destination out fifo */

        /* Set up source1.  For now, assume no stride and increment.
         * A channel attribute update can change this later.
         */
        switch (stp->dev_tsize) {
        case 1:
                src1 |= DSCR_SRC1_STS(DSCR_xTS_SIZE1);
                break;
        case 2:
                src1 |= DSCR_SRC1_STS(DSCR_xTS_SIZE2);
                break;
        case 4:
                src1 |= DSCR_SRC1_STS(DSCR_xTS_SIZE4);
                break;
        case 8:
        default:
                src1 |= DSCR_SRC1_STS(DSCR_xTS_SIZE8);
                break;
        }

        /* If source input is fifo, set static address.
        */
        if (stp->dev_flags & DEV_FLAGS_IN) {
                if ( stp->dev_flags & DEV_FLAGS_BURSTABLE )
                        src1 |= DSCR_SRC1_SAM(DSCR_xAM_BURST);
                else
                src1 |= DSCR_SRC1_SAM(DSCR_xAM_STATIC);

        }
        if (stp->dev_physaddr)
                src0 = stp->dev_physaddr;

        /* Set up dest1.  For now, assume no stride and increment.
         * A channel attribute update can change this later.
         */
        switch (dtp->dev_tsize) {
        case 1:
                dest1 |= DSCR_DEST1_DTS(DSCR_xTS_SIZE1);
                break;
        case 2:
                dest1 |= DSCR_DEST1_DTS(DSCR_xTS_SIZE2);
                break;
        case 4:
                dest1 |= DSCR_DEST1_DTS(DSCR_xTS_SIZE4);
                break;
        case 8:
        default:
                dest1 |= DSCR_DEST1_DTS(DSCR_xTS_SIZE8);
                break;
        }

        /* If destination output is fifo, set static address.
        */
        if (dtp->dev_flags & DEV_FLAGS_OUT) {
                if ( dtp->dev_flags & DEV_FLAGS_BURSTABLE )
                        dest1 |= DSCR_DEST1_DAM(DSCR_xAM_BURST);
                                else
                dest1 |= DSCR_DEST1_DAM(DSCR_xAM_STATIC);
        }
        if (dtp->dev_physaddr)
                dest0 = dtp->dev_physaddr;

#if 0
                printk("did:%x sid:%x cmd0:%x cmd1:%x source0:%x source1:%x dest0:%x dest1:%x\n",
                        dtp->dev_id, stp->dev_id, cmd0, cmd1, src0, src1, dest0, dest1 );
#endif
        for (i=0; i<entries; i++) {
                dp->dscr_cmd0 = cmd0;
                dp->dscr_cmd1 = cmd1;
                dp->dscr_source0 = src0;
                dp->dscr_source1 = src1;
                dp->dscr_dest0 = dest0;
                dp->dscr_dest1 = dest1;
                dp->dscr_stat = 0;
                                dp->sw_context = dp->sw_status = 0;
                dp->dscr_nxtptr = DSCR_NXTPTR(virt_to_phys(dp + 1));
                dp++;
        }

        /* Make last descrptor point to the first.
        */
        dp--;
        dp->dscr_nxtptr = DSCR_NXTPTR(virt_to_phys(ctp->chan_desc_base));
        ctp->get_ptr = ctp->put_ptr = ctp->cur_ptr = ctp->chan_desc_base;

        return (u32)(ctp->chan_desc_base);
}
EXPORT_SYMBOL(au1xxx_dbdma_ring_alloc);

/* Put a source buffer into the DMA ring.
 * This updates the source pointer and byte count.  Normally used
 * for memory to fifo transfers.
 */
u32
_au1xxx_dbdma_put_source(u32 chanid, void *buf, int nbytes, u32 flags)
{
        chan_tab_t              *ctp;
        au1x_ddma_desc_t        *dp;

        /* I guess we could check this to be within the
         * range of the table......
         */
        ctp = *((chan_tab_t **)chanid);

        /* We should have multiple callers for a particular channel,
         * an interrupt doesn't affect this pointer nor the descriptor,
         * so no locking should be needed.
         */
        dp = ctp->put_ptr;

        /* If the descriptor is valid, we are way ahead of the DMA
         * engine, so just return an error condition.
         */
        if (dp->dscr_cmd0 & DSCR_CMD0_V) {
                return 0;
        }

        /* Load up buffer address and byte count.
        */
        dp->dscr_source0 = virt_to_phys(buf);
        dp->dscr_cmd1 = nbytes;
        /* Check flags  */
        if (flags & DDMA_FLAGS_IE)
                dp->dscr_cmd0 |= DSCR_CMD0_IE;
        if (flags & DDMA_FLAGS_NOIE)
                dp->dscr_cmd0 &= ~DSCR_CMD0_IE;
        /* Get next descriptor pointer.
        */
        ctp->put_ptr = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));

        /*
         * There is an errata on the Au1200/Au1550 parts that could result
         * in "stale" data being DMA'd. It has to do with the snoop logic on
         * the dache eviction buffer.  NONCOHERENT_IO is on by default for
         * these parts. If it is fixedin the future, these dma_cache_inv will
         * just be nothing more than empty macros. See io.h.
         * */
        dma_cache_wback_inv((unsigned long)buf, nbytes);
        dp->dscr_cmd0 |= DSCR_CMD0_V;        /* Let it rip */
        au_sync();
        dma_cache_wback_inv((unsigned long)dp, sizeof(dp));
        ctp->chan_ptr->ddma_dbell = 0;

        /* return something not zero.
        */
        return nbytes;
}
EXPORT_SYMBOL(_au1xxx_dbdma_put_source);

/* Put a destination buffer into the DMA ring.
 * This updates the destination pointer and byte count.  Normally used
 * to place an empty buffer into the ring for fifo to memory transfers.
 */
u32
_au1xxx_dbdma_put_dest(u32 chanid, void *buf, int nbytes, u32 flags)
{
        chan_tab_t              *ctp;
        au1x_ddma_desc_t        *dp;

        /* I guess we could check this to be within the
         * range of the table......
         */
        ctp = *((chan_tab_t **)chanid);

        /* We should have multiple callers for a particular channel,
         * an interrupt doesn't affect this pointer nor the descriptor,
         * so no locking should be needed.
         */
        dp = ctp->put_ptr;

        /* If the descriptor is valid, we are way ahead of the DMA
         * engine, so just return an error condition.
         */
        if (dp->dscr_cmd0 & DSCR_CMD0_V)
                return 0;

        /* Load up buffer address and byte count */

        /* Check flags  */
        if (flags & DDMA_FLAGS_IE)
                dp->dscr_cmd0 |= DSCR_CMD0_IE;
        if (flags & DDMA_FLAGS_NOIE)
                dp->dscr_cmd0 &= ~DSCR_CMD0_IE;

        dp->dscr_dest0 = virt_to_phys(buf);
        dp->dscr_cmd1 = nbytes;
#if 0
        printk("cmd0:%x cmd1:%x source0:%x source1:%x dest0:%x dest1:%x\n",
                        dp->dscr_cmd0, dp->dscr_cmd1, dp->dscr_source0,
                        dp->dscr_source1, dp->dscr_dest0, dp->dscr_dest1 );
#endif
        /*
         * There is an errata on the Au1200/Au1550 parts that could result in
         * "stale" data being DMA'd. It has to do with the snoop logic on the
         * dache eviction buffer. NONCOHERENT_IO is on by default for these
         * parts. If it is fixedin the future, these dma_cache_inv will just
         * be nothing more than empty macros. See io.h.
         * */
        dma_cache_inv((unsigned long)buf,nbytes);
        dp->dscr_cmd0 |= DSCR_CMD0_V;   /* Let it rip */
        au_sync();
        dma_cache_wback_inv((unsigned long)dp, sizeof(dp));
        ctp->chan_ptr->ddma_dbell = 0;

        /* Get next descriptor pointer.
        */
        ctp->put_ptr = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));

        /* return something not zero.
        */
        return nbytes;
}
EXPORT_SYMBOL(_au1xxx_dbdma_put_dest);

/* Get a destination buffer into the DMA ring.
 * Normally used to get a full buffer from the ring during fifo
 * to memory transfers.  This does not set the valid bit, you will
 * have to put another destination buffer to keep the DMA going.
 */
u32
au1xxx_dbdma_get_dest(u32 chanid, void **buf, int *nbytes)
{
        chan_tab_t              *ctp;
        au1x_ddma_desc_t        *dp;
        u32                     rv;

        /* I guess we could check this to be within the
         * range of the table......
         */
        ctp = *((chan_tab_t **)chanid);

        /* We should have multiple callers for a particular channel,
         * an interrupt doesn't affect this pointer nor the descriptor,
         * so no locking should be needed.
         */
        dp = ctp->get_ptr;

        /* If the descriptor is valid, we are way ahead of the DMA
         * engine, so just return an error condition.
         */
        if (dp->dscr_cmd0 & DSCR_CMD0_V)
                return 0;

        /* Return buffer address and byte count.
        */
        *buf = (void *)(phys_to_virt(dp->dscr_dest0));
        *nbytes = dp->dscr_cmd1;
        rv = dp->dscr_stat;

        /* Get next descriptor pointer.
        */
        ctp->get_ptr = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));

        /* return something not zero.
        */
        return rv;
}

void
au1xxx_dbdma_stop(u32 chanid)
{
        chan_tab_t      *ctp;
        au1x_dma_chan_t *cp;
        int halt_timeout = 0;

        ctp = *((chan_tab_t **)chanid);

        cp = ctp->chan_ptr;
        cp->ddma_cfg &= ~DDMA_CFG_EN;   /* Disable channel */
        au_sync();
        while (!(cp->ddma_stat & DDMA_STAT_H)) {
                udelay(1);
                halt_timeout++;
                if (halt_timeout > 100) {
                        printk("warning: DMA channel won't halt\n");
                        break;
                }
        }
        /* clear current desc valid and doorbell */
        cp->ddma_stat |= (DDMA_STAT_DB | DDMA_STAT_V);
        au_sync();
}
EXPORT_SYMBOL(au1xxx_dbdma_stop);

/* Start using the current descriptor pointer.  If the dbdma encounters
 * a not valid descriptor, it will stop.  In this case, we can just
 * continue by adding a buffer to the list and starting again.
 */
void
au1xxx_dbdma_start(u32 chanid)
{
        chan_tab_t      *ctp;
        au1x_dma_chan_t *cp;

        ctp = *((chan_tab_t **)chanid);
        cp = ctp->chan_ptr;
        cp->ddma_desptr = virt_to_phys(ctp->cur_ptr);
        cp->ddma_cfg |= DDMA_CFG_EN;    /* Enable channel */
        au_sync();
        cp->ddma_dbell = 0;
        au_sync();
}
EXPORT_SYMBOL(au1xxx_dbdma_start);

void
au1xxx_dbdma_reset(u32 chanid)
{
        chan_tab_t              *ctp;
        au1x_ddma_desc_t        *dp;

        au1xxx_dbdma_stop(chanid);

        ctp = *((chan_tab_t **)chanid);
        ctp->get_ptr = ctp->put_ptr = ctp->cur_ptr = ctp->chan_desc_base;

        /* Run through the descriptors and reset the valid indicator.
        */
        dp = ctp->chan_desc_base;

        do {
                dp->dscr_cmd0 &= ~DSCR_CMD0_V;
                /* reset our SW status -- this is used to determine
                 * if a descriptor is in use by upper level SW. Since
                 * posting can reset 'V' bit.
                 */
                dp->sw_status = 0;
                dp = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));
        } while (dp != ctp->chan_desc_base);
}
EXPORT_SYMBOL(au1xxx_dbdma_reset);

u32
au1xxx_get_dma_residue(u32 chanid)
{
        chan_tab_t      *ctp;
        au1x_dma_chan_t *cp;
        u32             rv;

        ctp = *((chan_tab_t **)chanid);
        cp = ctp->chan_ptr;

        /* This is only valid if the channel is stopped.
        */
        rv = cp->ddma_bytecnt;
        au_sync();

        return rv;
}

void
au1xxx_dbdma_chan_free(u32 chanid)
{
        chan_tab_t      *ctp;
        dbdev_tab_t     *stp, *dtp;

        ctp = *((chan_tab_t **)chanid);
        stp = ctp->chan_src;
        dtp = ctp->chan_dest;

        au1xxx_dbdma_stop(chanid);

        kfree((void *)ctp->chan_desc_base);

        stp->dev_flags &= ~DEV_FLAGS_INUSE;
        dtp->dev_flags &= ~DEV_FLAGS_INUSE;
        chan_tab_ptr[ctp->chan_index] = NULL;

        kfree(ctp);
}
EXPORT_SYMBOL(au1xxx_dbdma_chan_free);

static irqreturn_t
dbdma_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        u32 intstat;
        u32 chan_index;
        chan_tab_t              *ctp;
        au1x_ddma_desc_t        *dp;
        au1x_dma_chan_t *cp;

        intstat = dbdma_gptr->ddma_intstat;
        au_sync();
        chan_index = au_ffs(intstat) - 1;

        ctp = chan_tab_ptr[chan_index];
        cp = ctp->chan_ptr;
        dp = ctp->cur_ptr;

        /* Reset interrupt.
        */
        cp->ddma_irq = 0;
        au_sync();

        if (ctp->chan_callback)
                (ctp->chan_callback)(irq, ctp->chan_callparam, regs);

        ctp->cur_ptr = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));
        return IRQ_RETVAL(1);
}

static void au1xxx_dbdma_init(void)
{
        int irq_nr;

        dbdma_gptr->ddma_config = 0;
        dbdma_gptr->ddma_throttle = 0;
        dbdma_gptr->ddma_inten = 0xffff;
        au_sync();

#if defined(CONFIG_SOC_AU1550)
        irq_nr = AU1550_DDMA_INT;
#elif defined(CONFIG_SOC_AU1200)
        irq_nr = AU1200_DDMA_INT;
#else
        #error Unknown Au1x00 SOC
#endif

        if (request_irq(irq_nr, dbdma_interrupt, SA_INTERRUPT,
                        "Au1xxx dbdma", (void *)dbdma_gptr))
                printk("Can't get 1550 dbdma irq");
}

void
au1xxx_dbdma_dump(u32 chanid)
{
        chan_tab_t              *ctp;
        au1x_ddma_desc_t        *dp;
        dbdev_tab_t             *stp, *dtp;
        au1x_dma_chan_t *cp;
                u32                     i = 0;

        ctp = *((chan_tab_t **)chanid);
        stp = ctp->chan_src;
        dtp = ctp->chan_dest;
        cp = ctp->chan_ptr;

        printk("Chan %x, stp %x (dev %d)  dtp %x (dev %d) \n",
                (u32)ctp, (u32)stp, stp - dbdev_tab, (u32)dtp, dtp - dbdev_tab);
        printk("desc base %x, get %x, put %x, cur %x\n",
                (u32)(ctp->chan_desc_base), (u32)(ctp->get_ptr),
                (u32)(ctp->put_ptr), (u32)(ctp->cur_ptr));

        printk("dbdma chan %x\n", (u32)cp);
        printk("cfg %08x, desptr %08x, statptr %08x\n",
                cp->ddma_cfg, cp->ddma_desptr, cp->ddma_statptr);
        printk("dbell %08x, irq %08x, stat %08x, bytecnt %08x\n",
                cp->ddma_dbell, cp->ddma_irq, cp->ddma_stat, cp->ddma_bytecnt);


        /* Run through the descriptors
        */
        dp = ctp->chan_desc_base;

        do {
                printk("Dp[%d]= %08x, cmd0 %08x, cmd1 %08x\n",
                        i++, (u32)dp, dp->dscr_cmd0, dp->dscr_cmd1);
                printk("src0 %08x, src1 %08x, dest0 %08x, dest1 %08x\n",
                        dp->dscr_source0, dp->dscr_source1, dp->dscr_dest0, dp->dscr_dest1);
                printk("stat %08x, nxtptr %08x\n",
                        dp->dscr_stat, dp->dscr_nxtptr);
                dp = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));
        } while (dp != ctp->chan_desc_base);
}

/* Put a descriptor into the DMA ring.
 * This updates the source/destination pointers and byte count.
 */
u32
au1xxx_dbdma_put_dscr(u32 chanid, au1x_ddma_desc_t *dscr )
{
        chan_tab_t *ctp;
        au1x_ddma_desc_t *dp;
        u32 nbytes=0;

        /* I guess we could check this to be within the
        * range of the table......
        */
        ctp = *((chan_tab_t **)chanid);

        /* We should have multiple callers for a particular channel,
        * an interrupt doesn't affect this pointer nor the descriptor,
        * so no locking should be needed.
        */
        dp = ctp->put_ptr;

        /* If the descriptor is valid, we are way ahead of the DMA
        * engine, so just return an error condition.
        */
        if (dp->dscr_cmd0 & DSCR_CMD0_V)
                return 0;

        /* Load up buffer addresses and byte count.
        */
        dp->dscr_dest0 = dscr->dscr_dest0;
        dp->dscr_source0 = dscr->dscr_source0;
        dp->dscr_dest1 = dscr->dscr_dest1;
        dp->dscr_source1 = dscr->dscr_source1;
        dp->dscr_cmd1 = dscr->dscr_cmd1;
        nbytes = dscr->dscr_cmd1;
        /* Allow the caller to specifiy if an interrupt is generated */
        dp->dscr_cmd0 &= ~DSCR_CMD0_IE;
        dp->dscr_cmd0 |= dscr->dscr_cmd0 | DSCR_CMD0_V;
        ctp->chan_ptr->ddma_dbell = 0;

        /* Get next descriptor pointer.
        */
        ctp->put_ptr = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));

        /* return something not zero.
        */
        return nbytes;
}

#endif /* defined(CONFIG_SOC_AU1550) || defined(CONFIG_SOC_AU1200) */