/*
 * IBM PPC4xx DMA engine scatter/gather library
 *
 * Copyright 2002-2003 MontaVista Software Inc.
 *
 * Cleaned up and converted to new DCR access
 * Matt Porter <mporter@kernel.crashing.org>
 *
 * Original code by Armin Kuster <akuster@mvista.com>
 * and Pete Popov <ppopov@mvista.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.
 *
 * 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/kernel.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/dma-mapping.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/ppc4xx_dma.h>

void
ppc4xx_set_sg_addr(int dmanr, phys_addr_t sg_addr)
{
        if (dmanr >= MAX_PPC4xx_DMA_CHANNELS) {
                printk("ppc4xx_set_sg_addr: bad channel: %d\n", dmanr);
                return;
        }

#ifdef PPC4xx_DMA_64BIT
        mtdcr(DCRN_ASGH0 + (dmanr * 0x8), (u32)(sg_addr >> 32));
#endif
        mtdcr(DCRN_ASG0 + (dmanr * 0x8), (u32)sg_addr);
}

/*
 *   Add a new sgl descriptor to the end of a scatter/gather list
 *   which was created by alloc_dma_handle().
 *
 *   For a memory to memory transfer, both dma addresses must be
 *   valid. For a peripheral to memory transfer, one of the addresses
 *   must be set to NULL, depending on the direction of the transfer:
 *   memory to peripheral: set dst_addr to NULL,
 *   peripheral to memory: set src_addr to NULL.
 */
int
ppc4xx_add_dma_sgl(sgl_handle_t handle, phys_addr_t src_addr, phys_addr_t dst_addr,
                   unsigned int count)
{
        sgl_list_info_t *psgl = (sgl_list_info_t *) handle;
        ppc_dma_ch_t *p_dma_ch;

        if (!handle) {
                printk("ppc4xx_add_dma_sgl: null handle\n");
                return DMA_STATUS_BAD_HANDLE;
        }

        if (psgl->dmanr >= MAX_PPC4xx_DMA_CHANNELS) {
                printk("ppc4xx_add_dma_sgl: bad channel: %d\n", psgl->dmanr);
                return DMA_STATUS_BAD_CHANNEL;
        }

        p_dma_ch = &dma_channels[psgl->dmanr];

#ifdef DEBUG_4xxDMA
        {
                int error = 0;
                unsigned int aligned =
                    (unsigned) src_addr | (unsigned) dst_addr | count;
                switch (p_dma_ch->pwidth) {
                case PW_8:
                        break;
                case PW_16:
                        if (aligned & 0x1)
                                error = 1;
                        break;
                case PW_32:
                        if (aligned & 0x3)
                                error = 1;
                        break;
                case PW_64:
                        if (aligned & 0x7)
                                error = 1;
                        break;
                default:
                        printk("ppc4xx_add_dma_sgl: invalid bus width: 0x%x\n",
                               p_dma_ch->pwidth);
                        return DMA_STATUS_GENERAL_ERROR;
                }
                if (error)
                        printk
                            ("Alignment warning: ppc4xx_add_dma_sgl src 0x%x dst 0x%x count 0x%x bus width var %d\n",
                             src_addr, dst_addr, count, p_dma_ch->pwidth);

        }
#endif

        if ((unsigned) (psgl->ptail + 1) >= ((unsigned) psgl + SGL_LIST_SIZE)) {
                printk("sgl handle out of memory \n");
                return DMA_STATUS_OUT_OF_MEMORY;
        }

        if (!psgl->ptail) {
                psgl->phead = (ppc_sgl_t *)
                    ((unsigned) psgl + sizeof (sgl_list_info_t));
                psgl->phead_dma = psgl->dma_addr + sizeof(sgl_list_info_t);
                psgl->ptail = psgl->phead;
                psgl->ptail_dma = psgl->phead_dma;
        } else {
                if(p_dma_ch->int_on_final_sg) {
                        /* mask out all dma interrupts, except error, on tail
                        before adding new tail. */
                        psgl->ptail->control_count &=
                                ~(SG_TCI_ENABLE | SG_ETI_ENABLE);
                }
                psgl->ptail->next = psgl->ptail_dma + sizeof(ppc_sgl_t);
                psgl->ptail++;
                psgl->ptail_dma += sizeof(ppc_sgl_t);
        }

        psgl->ptail->control = psgl->control;
        psgl->ptail->src_addr = src_addr;
        psgl->ptail->dst_addr = dst_addr;
        psgl->ptail->control_count = (count >> p_dma_ch->shift) |
            psgl->sgl_control;
        psgl->ptail->next = (uint32_t) NULL;

        return DMA_STATUS_GOOD;
}

/*
 * Enable (start) the DMA described by the sgl handle.
 */
void
ppc4xx_enable_dma_sgl(sgl_handle_t handle)
{
        sgl_list_info_t *psgl = (sgl_list_info_t *) handle;
        ppc_dma_ch_t *p_dma_ch;
        uint32_t sg_command;

        if (!handle) {
                printk("ppc4xx_enable_dma_sgl: null handle\n");
                return;
        } else if (psgl->dmanr > (MAX_PPC4xx_DMA_CHANNELS - 1)) {
                printk("ppc4xx_enable_dma_sgl: bad channel in handle %d\n",
                       psgl->dmanr);
                return;
        } else if (!psgl->phead) {
                printk("ppc4xx_enable_dma_sgl: sg list empty\n");
                return;
        }

        p_dma_ch = &dma_channels[psgl->dmanr];
        psgl->ptail->control_count &= ~SG_LINK; /* make this the last dscrptr */
        sg_command = mfdcr(DCRN_ASGC);

        ppc4xx_set_sg_addr(psgl->dmanr, psgl->phead_dma);

        sg_command |= SSG_ENABLE(psgl->dmanr);

        mtdcr(DCRN_ASGC, sg_command);   /* start transfer */
}

/*
 * Halt an active scatter/gather DMA operation.
 */
void
ppc4xx_disable_dma_sgl(sgl_handle_t handle)
{
        sgl_list_info_t *psgl = (sgl_list_info_t *) handle;
        uint32_t sg_command;

        if (!handle) {
                printk("ppc4xx_enable_dma_sgl: null handle\n");
                return;
        } else if (psgl->dmanr > (MAX_PPC4xx_DMA_CHANNELS - 1)) {
                printk("ppc4xx_enable_dma_sgl: bad channel in handle %d\n",
                       psgl->dmanr);
                return;
        }

        sg_command = mfdcr(DCRN_ASGC);
        sg_command &= ~SSG_ENABLE(psgl->dmanr);
        mtdcr(DCRN_ASGC, sg_command);   /* stop transfer */
}

/*
 *  Returns number of bytes left to be transferred from the entire sgl list.
 *  *src_addr and *dst_addr get set to the source/destination address of
 *  the sgl descriptor where the DMA stopped.
 *
 *  An sgl transfer must NOT be active when this function is called.
 */
int
ppc4xx_get_dma_sgl_residue(sgl_handle_t handle, phys_addr_t * src_addr,
                           phys_addr_t * dst_addr)
{
        sgl_list_info_t *psgl = (sgl_list_info_t *) handle;
        ppc_dma_ch_t *p_dma_ch;
        ppc_sgl_t *pnext, *sgl_addr;
        uint32_t count_left;

        if (!handle) {
                printk("ppc4xx_get_dma_sgl_residue: null handle\n");
                return DMA_STATUS_BAD_HANDLE;
        } else if (psgl->dmanr > (MAX_PPC4xx_DMA_CHANNELS - 1)) {
                printk("ppc4xx_get_dma_sgl_residue: bad channel in handle %d\n",
                       psgl->dmanr);
                return DMA_STATUS_BAD_CHANNEL;
        }

        sgl_addr = (ppc_sgl_t *) __va(mfdcr(DCRN_ASG0 + (psgl->dmanr * 0x8)));
        count_left = mfdcr(DCRN_DMACT0 + (psgl->dmanr * 0x8)) & SG_COUNT_MASK;

        if (!sgl_addr) {
                printk("ppc4xx_get_dma_sgl_residue: sgl addr register is null\n");
                goto error;
        }

        pnext = psgl->phead;
        while (pnext &&
               ((unsigned) pnext < ((unsigned) psgl + SGL_LIST_SIZE) &&
                (pnext != sgl_addr))
            ) {
                pnext++;
        }

        if (pnext == sgl_addr) {        /* found the sgl descriptor */

                *src_addr = pnext->src_addr;
                *dst_addr = pnext->dst_addr;

                /*
                 * Now search the remaining descriptors and add their count.
                 * We already have the remaining count from this descriptor in
                 * count_left.
                 */
                pnext++;

                while ((pnext != psgl->ptail) &&
                       ((unsigned) pnext < ((unsigned) psgl + SGL_LIST_SIZE))
                    ) {
                        count_left += pnext->control_count & SG_COUNT_MASK;
                }

                if (pnext != psgl->ptail) {     /* should never happen */
                        printk
                            ("ppc4xx_get_dma_sgl_residue error (1) psgl->ptail 0x%x handle 0x%x\n",
                             (unsigned int) psgl->ptail, (unsigned int) handle);
                        goto error;
                }

                /* success */
                p_dma_ch = &dma_channels[psgl->dmanr];
                return (count_left << p_dma_ch->shift); /* count in bytes */

        } else {
                /* this shouldn't happen */
                printk
                    ("get_dma_sgl_residue, unable to match current address 0x%x, handle 0x%x\n",
                     (unsigned int) sgl_addr, (unsigned int) handle);

        }

      error:
        *src_addr = (phys_addr_t) NULL;
        *dst_addr = (phys_addr_t) NULL;
        return 0;
}

/*
 * Returns the address(es) of the buffer(s) contained in the head element of
 * the scatter/gather list.  The element is removed from the scatter/gather
 * list and the next element becomes the head.
 *
 * This function should only be called when the DMA is not active.
 */
int
ppc4xx_delete_dma_sgl_element(sgl_handle_t handle, phys_addr_t * src_dma_addr,
                              phys_addr_t * dst_dma_addr)
{
        sgl_list_info_t *psgl = (sgl_list_info_t *) handle;

        if (!handle) {
                printk("ppc4xx_delete_sgl_element: null handle\n");
                return DMA_STATUS_BAD_HANDLE;
        } else if (psgl->dmanr > (MAX_PPC4xx_DMA_CHANNELS - 1)) {
                printk("ppc4xx_delete_sgl_element: bad channel in handle %d\n",
                       psgl->dmanr);
                return DMA_STATUS_BAD_CHANNEL;
        }

        if (!psgl->phead) {
                printk("ppc4xx_delete_sgl_element: sgl list empty\n");
                *src_dma_addr = (phys_addr_t) NULL;
                *dst_dma_addr = (phys_addr_t) NULL;
                return DMA_STATUS_SGL_LIST_EMPTY;
        }

        *src_dma_addr = (phys_addr_t) psgl->phead->src_addr;
        *dst_dma_addr = (phys_addr_t) psgl->phead->dst_addr;

        if (psgl->phead == psgl->ptail) {
                /* last descriptor on the list */
                psgl->phead = NULL;
                psgl->ptail = NULL;
        } else {
                psgl->phead++;
                psgl->phead_dma += sizeof(ppc_sgl_t);
        }

        return DMA_STATUS_GOOD;
}


/*
 *   Create a scatter/gather list handle.  This is simply a structure which
 *   describes a scatter/gather list.
 *
 *   A handle is returned in "handle" which the driver should save in order to
 *   be able to access this list later.  A chunk of memory will be allocated
 *   to be used by the API for internal management purposes, including managing
 *   the sg list and allocating memory for the sgl descriptors.  One page should
 *   be more than enough for that purpose.  Perhaps it's a bit wasteful to use
 *   a whole page for a single sg list, but most likely there will be only one
 *   sg list per channel.
 *
 *   Interrupt notes:
 *   Each sgl descriptor has a copy of the DMA control word which the DMA engine
 *   loads in the control register.  The control word has a "global" interrupt
 *   enable bit for that channel. Interrupts are further qualified by a few bits
 *   in the sgl descriptor count register.  In order to setup an sgl, we have to
 *   know ahead of time whether or not interrupts will be enabled at the completion
 *   of the transfers.  Thus, enable_dma_interrupt()/disable_dma_interrupt() MUST
 *   be called before calling alloc_dma_handle().  If the interrupt mode will never
 *   change after powerup, then enable_dma_interrupt()/disable_dma_interrupt()
 *   do not have to be called -- interrupts will be enabled or disabled based
 *   on how the channel was configured after powerup by the hw_init_dma_channel()
 *   function.  Each sgl descriptor will be setup to interrupt if an error occurs;
 *   however, only the last descriptor will be setup to interrupt. Thus, an
 *   interrupt will occur (if interrupts are enabled) only after the complete
 *   sgl transfer is done.
 */
int
ppc4xx_alloc_dma_handle(sgl_handle_t * phandle, unsigned int mode, unsigned int dmanr)
{
        sgl_list_info_t *psgl=NULL;
        dma_addr_t dma_addr;
        ppc_dma_ch_t *p_dma_ch = &dma_channels[dmanr];
        uint32_t sg_command;
        uint32_t ctc_settings;
        void *ret;

        if (dmanr >= MAX_PPC4xx_DMA_CHANNELS) {
                printk("ppc4xx_alloc_dma_handle: invalid channel 0x%x\n", dmanr);
                return DMA_STATUS_BAD_CHANNEL;
        }

        if (!phandle) {
                printk("ppc4xx_alloc_dma_handle: null handle pointer\n");
                return DMA_STATUS_NULL_POINTER;
        }

        /* Get a page of memory, which is zeroed out by consistent_alloc() */
        ret = dma_alloc_coherent(NULL, DMA_PPC4xx_SIZE, &dma_addr, GFP_KERNEL);
        if (ret != NULL) {
                memset(ret, 0, DMA_PPC4xx_SIZE);
                psgl = (sgl_list_info_t *) ret;
        }

        if (psgl == NULL) {
                *phandle = (sgl_handle_t) NULL;
                return DMA_STATUS_OUT_OF_MEMORY;
        }

        psgl->dma_addr = dma_addr;
        psgl->dmanr = dmanr;

        /*
         * Modify and save the control word. These words will be
         * written to each sgl descriptor.  The DMA engine then
         * loads this control word into the control register
         * every time it reads a new descriptor.
         */
        psgl->control = p_dma_ch->control;
        /* Clear all mode bits */
        psgl->control &= ~(DMA_TM_MASK | DMA_TD);
        /* Save control word and mode */
        psgl->control |= (mode | DMA_CE_ENABLE);

        /* In MM mode, we must set ETD/TCE */
        if (mode == DMA_MODE_MM)
                psgl->control |= DMA_ETD_OUTPUT | DMA_TCE_ENABLE;

        if (p_dma_ch->int_enable) {
                /* Enable channel interrupt */
                psgl->control |= DMA_CIE_ENABLE;
        } else {
                psgl->control &= ~DMA_CIE_ENABLE;
        }

        sg_command = mfdcr(DCRN_ASGC);
        sg_command |= SSG_MASK_ENABLE(dmanr);

        /* Enable SGL control access */
        mtdcr(DCRN_ASGC, sg_command);
        psgl->sgl_control = SG_ERI_ENABLE | SG_LINK;

        /* keep control count register settings */
        ctc_settings = mfdcr(DCRN_DMACT0 + (dmanr * 0x8))
                & (DMA_CTC_BSIZ_MSK | DMA_CTC_BTEN); /*burst mode settings*/
        psgl->sgl_control |= ctc_settings;

        if (p_dma_ch->int_enable) {
                if (p_dma_ch->tce_enable)
                        psgl->sgl_control |= SG_TCI_ENABLE;
                else
                        psgl->sgl_control |= SG_ETI_ENABLE;
        }

        *phandle = (sgl_handle_t) psgl;
        return DMA_STATUS_GOOD;
}

/*
 * Destroy a scatter/gather list handle that was created by alloc_dma_handle().
 * The list must be empty (contain no elements).
 */
void
ppc4xx_free_dma_handle(sgl_handle_t handle)
{
        sgl_list_info_t *psgl = (sgl_list_info_t *) handle;

        if (!handle) {
                printk("ppc4xx_free_dma_handle: got NULL\n");
                return;
        } else if (psgl->phead) {
                printk("ppc4xx_free_dma_handle: list not empty\n");
                return;
        } else if (!psgl->dma_addr) {   /* should never happen */
                printk("ppc4xx_free_dma_handle: no dma address\n");
                return;
        }

        dma_free_coherent(NULL, DMA_PPC4xx_SIZE, (void *) psgl, 0);
}

EXPORT_SYMBOL(ppc4xx_alloc_dma_handle);
EXPORT_SYMBOL(ppc4xx_free_dma_handle);
EXPORT_SYMBOL(ppc4xx_add_dma_sgl);
EXPORT_SYMBOL(ppc4xx_delete_dma_sgl_element);
EXPORT_SYMBOL(ppc4xx_enable_dma_sgl);
EXPORT_SYMBOL(ppc4xx_disable_dma_sgl);
EXPORT_SYMBOL(ppc4xx_get_dma_sgl_residue);