/*
 *  linux/arch/arm/mach-imx/dma.c
 *
 *  imx DMA registration and IRQ dispatching
 *
 *  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.
 *
 *  2004-03-03 Sascha Hauer <sascha@saschahauer.de>
 *             initial version heavily inspired by
 *             linux/arch/arm/mach-pxa/dma.c
 *
 *  2005-04-17 Pavel Pisa <pisa@cmp.felk.cvut.cz>
 *             Changed to support scatter gather DMA
 *             by taking Russell's code from RiscPC
 *
 *  2006-05-31 Pavel Pisa <pisa@cmp.felk.cvut.cz>
 *             Corrected error handling code.
 *
 */

#undef DEBUG

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/errno.h>

#include <asm/system.h>
#include <asm/irq.h>
#include <mach/hardware.h>
#include <asm/dma.h>
#include <mach/imx-dma.h>

struct imx_dma_channel imx_dma_channels[IMX_DMA_CHANNELS];

/*
 * imx_dma_sg_next - prepare next chunk for scatter-gather DMA emulation
 * @dma_ch: i.MX DMA channel number
 * @lastcount: number of bytes transferred during last transfer
 *
 * Functions prepares DMA controller for next sg data chunk transfer.
 * The @lastcount argument informs function about number of bytes transferred
 * during last block. Zero value can be used for @lastcount to setup DMA
 * for the first chunk.
 */
static inline int imx_dma_sg_next(imx_dmach_t dma_ch, unsigned int lastcount)
{
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
        unsigned int nextcount;
        unsigned int nextaddr;

        if (!imxdma->name) {
                printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
                       __func__, dma_ch);
                return 0;
        }

        imxdma->resbytes -= lastcount;

        if (!imxdma->sg) {
                pr_debug("imxdma%d: no sg data\n", dma_ch);
                return 0;
        }

        imxdma->sgbc += lastcount;
        if ((imxdma->sgbc >= imxdma->sg->length) || !imxdma->resbytes) {
                if ((imxdma->sgcount <= 1) || !imxdma->resbytes) {
                        pr_debug("imxdma%d: sg transfer limit reached\n",
                                 dma_ch);
                        imxdma->sgcount=0;
                        imxdma->sg = NULL;
                        return 0;
                } else {
                        imxdma->sgcount--;
                        imxdma->sg++;
                        imxdma->sgbc = 0;
                }
        }
        nextcount = imxdma->sg->length - imxdma->sgbc;
        nextaddr = imxdma->sg->dma_address + imxdma->sgbc;

        if(imxdma->resbytes < nextcount)
                nextcount = imxdma->resbytes;

        if ((imxdma->dma_mode & DMA_MODE_MASK) == DMA_MODE_READ)
                DAR(dma_ch) = nextaddr;
        else
                SAR(dma_ch) = nextaddr;

        CNTR(dma_ch) = nextcount;
        pr_debug("imxdma%d: next sg chunk dst 0x%08x, src 0x%08x, size 0x%08x\n",
                 dma_ch, DAR(dma_ch), SAR(dma_ch), CNTR(dma_ch));

        return nextcount;
}

/*
 * imx_dma_setup_sg_base - scatter-gather DMA emulation
 * @dma_ch: i.MX DMA channel number
 * @sg: pointer to the scatter-gather list/vector
 * @sgcount: scatter-gather list hungs count
 *
 * Functions sets up i.MX DMA state for emulated scatter-gather transfer
 * and sets up channel registers to be ready for the first chunk
 */
static int
imx_dma_setup_sg_base(imx_dmach_t dma_ch,
                      struct scatterlist *sg, unsigned int sgcount)
{
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];

        imxdma->sg = sg;
        imxdma->sgcount = sgcount;
        imxdma->sgbc = 0;
        return imx_dma_sg_next(dma_ch, 0);
}

/**
 * imx_dma_setup_single - setup i.MX DMA channel for linear memory to/from device transfer
 * @dma_ch: i.MX DMA channel number
 * @dma_address: the DMA/physical memory address of the linear data block
 *              to transfer
 * @dma_length: length of the data block in bytes
 * @dev_addr: physical device port address
 * @dmamode: DMA transfer mode, %DMA_MODE_READ from the device to the memory
 *           or %DMA_MODE_WRITE from memory to the device
 *
 * The function setups DMA channel source and destination addresses for transfer
 * specified by provided parameters. The scatter-gather emulation is disabled,
 * because linear data block
 * form the physical address range is transferred.
 * Return value: if incorrect parameters are provided -%EINVAL.
 *              Zero indicates success.
 */
int
imx_dma_setup_single(imx_dmach_t dma_ch, dma_addr_t dma_address,
                     unsigned int dma_length, unsigned int dev_addr,
                     dmamode_t dmamode)
{
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];

        imxdma->sg = NULL;
        imxdma->sgcount = 0;
        imxdma->dma_mode = dmamode;
        imxdma->resbytes = dma_length;

        if (!dma_address) {
                printk(KERN_ERR "imxdma%d: imx_dma_setup_single null address\n",
                       dma_ch);
                return -EINVAL;
        }

        if (!dma_length) {
                printk(KERN_ERR "imxdma%d: imx_dma_setup_single zero length\n",
                       dma_ch);
                return -EINVAL;
        }

        if ((dmamode & DMA_MODE_MASK) == DMA_MODE_READ) {
                pr_debug("imxdma%d: mx_dma_setup_single2dev dma_addressg=0x%08x dma_length=%d dev_addr=0x%08x for read\n",
                        dma_ch, (unsigned int)dma_address, dma_length,
                        dev_addr);
                SAR(dma_ch) = dev_addr;
                DAR(dma_ch) = (unsigned int)dma_address;
        } else if ((dmamode & DMA_MODE_MASK) == DMA_MODE_WRITE) {
                pr_debug("imxdma%d: mx_dma_setup_single2dev dma_addressg=0x%08x dma_length=%d dev_addr=0x%08x for write\n",
                        dma_ch, (unsigned int)dma_address, dma_length,
                        dev_addr);
                SAR(dma_ch) = (unsigned int)dma_address;
                DAR(dma_ch) = dev_addr;
        } else {
                printk(KERN_ERR "imxdma%d: imx_dma_setup_single bad dmamode\n",
                       dma_ch);
                return -EINVAL;
        }

        CNTR(dma_ch) = dma_length;

        return 0;
}

/**
 * imx_dma_setup_sg - setup i.MX DMA channel SG list to/from device transfer
 * @dma_ch: i.MX DMA channel number
 * @sg: pointer to the scatter-gather list/vector
 * @sgcount: scatter-gather list hungs count
 * @dma_length: total length of the transfer request in bytes
 * @dev_addr: physical device port address
 * @dmamode: DMA transfer mode, %DMA_MODE_READ from the device to the memory
 *           or %DMA_MODE_WRITE from memory to the device
 *
 * The function sets up DMA channel state and registers to be ready for transfer
 * specified by provided parameters. The scatter-gather emulation is set up
 * according to the parameters.
 *
 * The full preparation of the transfer requires setup of more register
 * by the caller before imx_dma_enable() can be called.
 *
 * %BLR(dma_ch) holds transfer burst length in bytes, 0 means 64 bytes
 *
 * %RSSR(dma_ch) has to be set to the DMA request line source %DMA_REQ_xxx
 *
 * %CCR(dma_ch) has to specify transfer parameters, the next settings is typical
 * for linear or simple scatter-gather transfers if %DMA_MODE_READ is specified
 *
 * %CCR_DMOD_LINEAR | %CCR_DSIZ_32 | %CCR_SMOD_FIFO | %CCR_SSIZ_x
 *
 * The typical setup for %DMA_MODE_WRITE is specified by next options combination
 *
 * %CCR_SMOD_LINEAR | %CCR_SSIZ_32 | %CCR_DMOD_FIFO | %CCR_DSIZ_x
 *
 * Be careful here and do not mistakenly mix source and target device
 * port sizes constants, they are really different:
 * %CCR_SSIZ_8, %CCR_SSIZ_16, %CCR_SSIZ_32,
 * %CCR_DSIZ_8, %CCR_DSIZ_16, %CCR_DSIZ_32
 *
 * Return value: if incorrect parameters are provided -%EINVAL.
 * Zero indicates success.
 */
int
imx_dma_setup_sg(imx_dmach_t dma_ch,
                 struct scatterlist *sg, unsigned int sgcount, unsigned int dma_length,
                 unsigned int dev_addr, dmamode_t dmamode)
{
        int res;
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];

        imxdma->sg = NULL;
        imxdma->sgcount = 0;
        imxdma->dma_mode = dmamode;
        imxdma->resbytes = dma_length;

        if (!sg || !sgcount) {
                printk(KERN_ERR "imxdma%d: imx_dma_setup_sg epty sg list\n",
                       dma_ch);
                return -EINVAL;
        }

        if (!sg->length) {
                printk(KERN_ERR "imxdma%d: imx_dma_setup_sg zero length\n",
                       dma_ch);
                return -EINVAL;
        }

        if ((dmamode & DMA_MODE_MASK) == DMA_MODE_READ) {
                pr_debug("imxdma%d: mx_dma_setup_sg2dev sg=%p sgcount=%d total length=%d dev_addr=0x%08x for read\n",
                        dma_ch, sg, sgcount, dma_length, dev_addr);
                SAR(dma_ch) = dev_addr;
        } else if ((dmamode & DMA_MODE_MASK) == DMA_MODE_WRITE) {
                pr_debug("imxdma%d: mx_dma_setup_sg2dev sg=%p sgcount=%d total length=%d dev_addr=0x%08x for write\n",
                        dma_ch, sg, sgcount, dma_length, dev_addr);
                DAR(dma_ch) = dev_addr;
        } else {
                printk(KERN_ERR "imxdma%d: imx_dma_setup_sg bad dmamode\n",
                       dma_ch);
                return -EINVAL;
        }

        res = imx_dma_setup_sg_base(dma_ch, sg, sgcount);
        if (res <= 0) {
                printk(KERN_ERR "imxdma%d: no sg chunk ready\n", dma_ch);
                return -EINVAL;
        }

        return 0;
}

/**
 * imx_dma_setup_handlers - setup i.MX DMA channel end and error notification handlers
 * @dma_ch: i.MX DMA channel number
 * @irq_handler: the pointer to the function called if the transfer
 *              ends successfully
 * @err_handler: the pointer to the function called if the premature
 *              end caused by error occurs
 * @data: user specified value to be passed to the handlers
 */
int
imx_dma_setup_handlers(imx_dmach_t dma_ch,
                       void (*irq_handler) (int, void *),
                       void (*err_handler) (int, void *, int),
                       void *data)
{
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
        unsigned long flags;

        if (!imxdma->name) {
                printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
                       __func__, dma_ch);
                return -ENODEV;
        }

        local_irq_save(flags);
        DISR = (1 << dma_ch);
        imxdma->irq_handler = irq_handler;
        imxdma->err_handler = err_handler;
        imxdma->data = data;
        local_irq_restore(flags);
        return 0;
}

/**
 * imx_dma_enable - function to start i.MX DMA channel operation
 * @dma_ch: i.MX DMA channel number
 *
 * The channel has to be allocated by driver through imx_dma_request()
 * or imx_dma_request_by_prio() function.
 * The transfer parameters has to be set to the channel registers through
 * call of the imx_dma_setup_single() or imx_dma_setup_sg() function
 * and registers %BLR(dma_ch), %RSSR(dma_ch) and %CCR(dma_ch) has to
 * be set prior this function call by the channel user.
 */
void imx_dma_enable(imx_dmach_t dma_ch)
{
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
        unsigned long flags;

        pr_debug("imxdma%d: imx_dma_enable\n", dma_ch);

        if (!imxdma->name) {
                printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
                       __func__, dma_ch);
                return;
        }

        local_irq_save(flags);
        DISR = (1 << dma_ch);
        DIMR &= ~(1 << dma_ch);
        CCR(dma_ch) |= CCR_CEN;
        local_irq_restore(flags);
}

/**
 * imx_dma_disable - stop, finish i.MX DMA channel operatin
 * @dma_ch: i.MX DMA channel number
 */
void imx_dma_disable(imx_dmach_t dma_ch)
{
        unsigned long flags;

        pr_debug("imxdma%d: imx_dma_disable\n", dma_ch);

        local_irq_save(flags);
        DIMR |= (1 << dma_ch);
        CCR(dma_ch) &= ~CCR_CEN;
        DISR = (1 << dma_ch);
        local_irq_restore(flags);
}

/**
 * imx_dma_request - request/allocate specified channel number
 * @dma_ch: i.MX DMA channel number
 * @name: the driver/caller own non-%NULL identification
 */
int imx_dma_request(imx_dmach_t dma_ch, const char *name)
{
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
        unsigned long flags;

        /* basic sanity checks */
        if (!name)
                return -EINVAL;

        if (dma_ch >= IMX_DMA_CHANNELS) {
                printk(KERN_CRIT "%s: called for  non-existed channel %d\n",
                       __func__, dma_ch);
                return -EINVAL;
        }

        local_irq_save(flags);
        if (imxdma->name) {
                local_irq_restore(flags);
                return -ENODEV;
        }

        imxdma->name = name;
        imxdma->irq_handler = NULL;
        imxdma->err_handler = NULL;
        imxdma->data = NULL;
        imxdma->sg = NULL;
        local_irq_restore(flags);
        return 0;
}

/**
 * imx_dma_free - release previously acquired channel
 * @dma_ch: i.MX DMA channel number
 */
void imx_dma_free(imx_dmach_t dma_ch)
{
        unsigned long flags;
        struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];

        if (!imxdma->name) {
                printk(KERN_CRIT
                       "%s: trying to free channel %d which is already freed\n",
                       __func__, dma_ch);
                return;
        }

        local_irq_save(flags);
        /* Disable interrupts */
        DIMR |= (1 << dma_ch);
        CCR(dma_ch) &= ~CCR_CEN;
        imxdma->name = NULL;
        local_irq_restore(flags);
}

/**
 * imx_dma_request_by_prio - find and request some of free channels best suiting requested priority
 * @name: the driver/caller own non-%NULL identification
 * @prio: one of the hardware distinguished priority level:
 *        %DMA_PRIO_HIGH, %DMA_PRIO_MEDIUM, %DMA_PRIO_LOW
 *
 * This function tries to find free channel in the specified priority group
 * if the priority cannot be achieved it tries to look for free channel
 * in the higher and then even lower priority groups.
 *
 * Return value: If there is no free channel to allocate, -%ENODEV is returned.
 *               On successful allocation channel is returned.
 */
imx_dmach_t imx_dma_request_by_prio(const char *name, imx_dma_prio prio)
{
        int i;
        int best;

        switch (prio) {
        case (DMA_PRIO_HIGH):
                best = 8;
                break;
        case (DMA_PRIO_MEDIUM):
                best = 4;
                break;
        case (DMA_PRIO_LOW):
        default:
                best = 0;
                break;
        }

        for (i = best; i < IMX_DMA_CHANNELS; i++) {
                if (!imx_dma_request(i, name)) {
                        return i;
                }
        }

        for (i = best - 1; i >= 0; i--) {
                if (!imx_dma_request(i, name)) {
                        return i;
                }
        }

        printk(KERN_ERR "%s: no free DMA channel found\n", __func__);

        return -ENODEV;
}

static irqreturn_t dma_err_handler(int irq, void *dev_id)
{
        int i, disr = DISR;
        struct imx_dma_channel *channel;
        unsigned int err_mask = DBTOSR | DRTOSR | DSESR | DBOSR;
        int errcode;

        DISR = disr & err_mask;
        for (i = 0; i < IMX_DMA_CHANNELS; i++) {
                if(!(err_mask & (1 << i)))
                        continue;
                channel = &imx_dma_channels[i];
                errcode = 0;

                if (DBTOSR & (1 << i)) {
                        DBTOSR = (1 << i);
                        errcode |= IMX_DMA_ERR_BURST;
                }
                if (DRTOSR & (1 << i)) {
                        DRTOSR = (1 << i);
                        errcode |= IMX_DMA_ERR_REQUEST;
                }
                if (DSESR & (1 << i)) {
                        DSESR = (1 << i);
                        errcode |= IMX_DMA_ERR_TRANSFER;
                }
                if (DBOSR & (1 << i)) {
                        DBOSR = (1 << i);
                        errcode |= IMX_DMA_ERR_BUFFER;
                }

                /*
                 * The cleaning of @sg field would be questionable
                 * there, because its value can help to compute
                 * remaining/transferred bytes count in the handler
                 */
                /*imx_dma_channels[i].sg = NULL;*/

                if (channel->name && channel->err_handler) {
                        channel->err_handler(i, channel->data, errcode);
                        continue;
                }

                imx_dma_channels[i].sg = NULL;

                printk(KERN_WARNING
                       "DMA timeout on channel %d (%s) -%s%s%s%s\n",
                       i, channel->name,
                       errcode&IMX_DMA_ERR_BURST?    " burst":"",
                       errcode&IMX_DMA_ERR_REQUEST?  " request":"",
                       errcode&IMX_DMA_ERR_TRANSFER? " transfer":"",
                       errcode&IMX_DMA_ERR_BUFFER?   " buffer":"");
        }
        return IRQ_HANDLED;
}

static irqreturn_t dma_irq_handler(int irq, void *dev_id)
{
        int i, disr = DISR;

        pr_debug("imxdma: dma_irq_handler called, disr=0x%08x\n",
                     disr);

        DISR = disr;
        for (i = 0; i < IMX_DMA_CHANNELS; i++) {
                if (disr & (1 << i)) {
                        struct imx_dma_channel *channel = &imx_dma_channels[i];
                        if (channel->name) {
                                if (imx_dma_sg_next(i, CNTR(i))) {
                                        CCR(i) &= ~CCR_CEN;
                                        mb();
                                        CCR(i) |= CCR_CEN;
                                } else {
                                        if (channel->irq_handler)
                                                channel->irq_handler(i,
                                                        channel->data);
                                }
                        } else {
                                /*
                                 * IRQ for an unregistered DMA channel:
                                 * let's clear the interrupts and disable it.
                                 */
                                printk(KERN_WARNING
                                       "spurious IRQ for DMA channel %d\n", i);
                        }
                }
        }
        return IRQ_HANDLED;
}

static int __init imx_dma_init(void)
{
        int ret;
        int i;

        /* reset DMA module */
        DCR = DCR_DRST;

        ret = request_irq(DMA_INT, dma_irq_handler, 0, "DMA", NULL);
        if (ret) {
                printk(KERN_CRIT "Wow!  Can't register IRQ for DMA\n");
                return ret;
        }

        ret = request_irq(DMA_ERR, dma_err_handler, 0, "DMA", NULL);
        if (ret) {
                printk(KERN_CRIT "Wow!  Can't register ERRIRQ for DMA\n");
                free_irq(DMA_INT, NULL);
        }

        /* enable DMA module */
        DCR = DCR_DEN;

        /* clear all interrupts */
        DISR = (1 << IMX_DMA_CHANNELS) - 1;

        /* enable interrupts */
        DIMR = (1 << IMX_DMA_CHANNELS) - 1;

        for (i = 0; i < IMX_DMA_CHANNELS; i++) {
                imx_dma_channels[i].sg = NULL;
                imx_dma_channels[i].dma_num = i;
        }

        return ret;
}

arch_initcall(imx_dma_init);

EXPORT_SYMBOL(imx_dma_setup_single);
EXPORT_SYMBOL(imx_dma_setup_sg);
EXPORT_SYMBOL(imx_dma_setup_handlers);
EXPORT_SYMBOL(imx_dma_enable);
EXPORT_SYMBOL(imx_dma_disable);
EXPORT_SYMBOL(imx_dma_request);
EXPORT_SYMBOL(imx_dma_free);
EXPORT_SYMBOL(imx_dma_request_by_prio);
EXPORT_SYMBOL(imx_dma_channels);