ppc405_dma.c

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/*
 * linux/arch/ppc/kernel/ppc405_dma.c
 *
 * BRIEF MODULE DESCRIPTION
 *	IBM 405 DMA Controller Functions
 *
 * Copyright 2000 MontaVista Software Inc.
 * Author: MontaVista Software, Inc.
 *         	[e-mail] or [e-mail]
 *
 *
 *  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 <asm/system.h>
#include <asm/io.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/init.h>
#include <linux/module.h>

#include <asm/ppc405_dma.h>


/*
 * Function prototypes
 */

int hw_init_dma_channel(unsigned int,  ppc_dma_ch_t *);
int init_dma_channel(unsigned int);
int get_channel_config(unsigned int, ppc_dma_ch_t *);
int set_channel_priority(unsigned int, unsigned int);
unsigned int get_peripheral_width(unsigned int);
int alloc_dma_handle(sgl_handle_t *, unsigned int, unsigned int);
void free_dma_handle(sgl_handle_t);


ppc_dma_ch_t dma_channels[MAX_405GP_DMA_CHANNELS];

/*
 * Configures a DMA channel, including the peripheral bus width, if a
 * peripheral is attached to the channel, the polarity of the DMAReq and
 * DMAAck signals, etc.  This information should really be setup by the boot 
 * code, since most likely the configuration won't change dynamically.
 * If the kernel has to call this function, it's recommended that it's
 * called from platform specific init code.  The driver should not need to 
 * call this function.
 */
int hw_init_dma_channel(unsigned int dmanr,  ppc_dma_ch_t *p_init)
{
    unsigned int polarity;
    uint32_t control = 0;
    ppc_dma_ch_t *p_dma_ch = &dma_channels[dmanr];

#ifdef DEBUG_405DMA
    if (!p_init) {
        printk("hw_init_dma_channel: NULL p_init\n");
        return DMA_STATUS_NULL_POINTER;
    }
    if (dmanr >= MAX_405GP_DMA_CHANNELS) {
        printk("hw_init_dma_channel: bad channel %d\n", dmanr);
        return DMA_STATUS_BAD_CHANNEL;
    }
#endif

#if DCRN_POL > 0
    polarity = mfdcr(DCRN_POL);
#else
    polarity = 0;
#endif

    /* Setup the control register based on the values passed to
     * us in p_init.  Then, over-write the control register with this
     * new value.
     */

    control |= ( 
                SET_DMA_CIE_ENABLE(p_init->int_enable) | /* interrupt enable         */
                SET_DMA_BEN(p_init->buffer_enable)     | /* buffer enable            */ 
                SET_DMA_ETD(p_init->etd_output)        | /* end of transfer pin      */
                SET_DMA_TCE(p_init->tce_enable)        | /* terminal count enable    */
                SET_DMA_PL(p_init->pl)                 | /* peripheral location      */
                SET_DMA_DAI(p_init->dai)               | /* dest addr increment      */
                SET_DMA_SAI(p_init->sai)               | /* src addr increment       */
                SET_DMA_PRIORITY(p_init->cp)           |  /* channel priority        */
                SET_DMA_PW(p_init->pwidth)             |  /* peripheral/bus width    */
                SET_DMA_PSC(p_init->psc)               |  /* peripheral setup cycles */
                SET_DMA_PWC(p_init->pwc)               |  /* peripheral wait cycles  */
                SET_DMA_PHC(p_init->phc)               |  /* peripheral hold cycles  */
                SET_DMA_PREFETCH(p_init->pf)              /* read prefetch           */
                );

    switch (dmanr) {
        case 0:
            /* clear all polarity signals and then "or" in new signal levels */
            polarity &= ~(DMAReq0_ActiveLow | DMAAck0_ActiveLow | EOT0_ActiveLow);
            polarity |= p_dma_ch->polarity;
#if DCRN_POL > 0
            mtdcr(DCRN_POL, polarity);
#endif
            mtdcr(DCRN_DMACR0, control);
            break;
        case 1:
            polarity &= ~(DMAReq1_ActiveLow | DMAAck1_ActiveLow | EOT1_ActiveLow);
            polarity |= p_dma_ch->polarity;
#if DCRN_POL > 0
            mtdcr(DCRN_POL, polarity);
#endif
            mtdcr(DCRN_DMACR1, control);
            break;
        case 2:
            polarity &= ~(DMAReq2_ActiveLow | DMAAck2_ActiveLow | EOT2_ActiveLow);
            polarity |= p_dma_ch->polarity;
#if DCRN_POL > 0
            mtdcr(DCRN_POL, polarity);
#endif
            mtdcr(DCRN_DMACR2, control);
            break;
        case 3:
            polarity &= ~(DMAReq3_ActiveLow | DMAAck3_ActiveLow | EOT3_ActiveLow);
            polarity |= p_dma_ch->polarity;
#if DCRN_POL > 0
            mtdcr(DCRN_POL, polarity);
#endif
            mtdcr(DCRN_DMACR3, control);
            break;
        default:
            return DMA_STATUS_BAD_CHANNEL;
    }
    
    /* save these values in our dma channel structure */
    memcpy(p_dma_ch, p_init, sizeof(ppc_dma_ch_t));

    /*
     * The peripheral width values written in the control register are:
     *   PW_8                 0
     *   PW_16                1
     *   PW_32                2
     *   PW_64                3
     *
     *   Since the DMA count register takes the number of "transfers",
     *   we need to divide the count sent to us in certain
     *   functions by the appropriate number.  It so happens that our
     *   right shift value is equal to the peripheral width value.
     */
    p_dma_ch->shift = p_init->pwidth;

    /*
     * Save the control word for easy access.
     */
    p_dma_ch->control = control;

    mtdcr(DCRN_DMASR, 0xffffffff); /* clear status register */
    return DMA_STATUS_GOOD;
}




/*
 * This function returns the channel configuration.
 */
int get_channel_config(unsigned int dmanr, ppc_dma_ch_t *p_dma_ch)
{
    unsigned int polarity;
    unsigned int control;

#if DCRN_POL > 0
    polarity = mfdcr(DCRN_POL);
#else
    polarity = 0;
#endif

    switch (dmanr) {
        case 0:
            p_dma_ch->polarity = 
                polarity & (DMAReq0_ActiveLow | DMAAck0_ActiveLow | EOT0_ActiveLow);
            control = mfdcr(DCRN_DMACR0);
            break;
        case 1:
            p_dma_ch->polarity = 
                polarity & (DMAReq1_ActiveLow | DMAAck1_ActiveLow | EOT1_ActiveLow);
            control = mfdcr(DCRN_DMACR1);
            break;
        case 2:
            p_dma_ch->polarity = 
                polarity & (DMAReq2_ActiveLow | DMAAck2_ActiveLow | EOT2_ActiveLow);
            control = mfdcr(DCRN_DMACR2);
            break;
        case 3:
            p_dma_ch->polarity = 
                polarity & (DMAReq3_ActiveLow | DMAAck3_ActiveLow | EOT3_ActiveLow);
            control = mfdcr(DCRN_DMACR3);
            break;
        default:
            return DMA_STATUS_BAD_CHANNEL;
    }

    p_dma_ch->cp = GET_DMA_PRIORITY(control);
    p_dma_ch->pwidth = GET_DMA_PW(control);
    p_dma_ch->psc = GET_DMA_PSC(control);
    p_dma_ch->pwc = GET_DMA_PWC(control);
    p_dma_ch->phc = GET_DMA_PHC(control);
    p_dma_ch->pf = GET_DMA_PREFETCH(control);
    p_dma_ch->int_enable = GET_DMA_CIE_ENABLE(control);
    p_dma_ch->shift = GET_DMA_PW(control);

    return DMA_STATUS_GOOD;
}

/*
 * Sets the priority for the DMA channel dmanr.
 * Since this is setup by the hardware init function, this function 
 * can be used to dynamically change the priority of a channel.
 *
 * Acceptable priorities:
 *
 * PRIORITY_LOW
 * PRIORITY_MID_LOW
 * PRIORITY_MID_HIGH
 * PRIORITY_HIGH
 *
 */
int set_channel_priority(unsigned int dmanr, unsigned int priority)
{
    unsigned int control;

#ifdef DEBUG_405DMA
    if ( (priority != PRIORITY_LOW) &&
            (priority != PRIORITY_MID_LOW) &&
            (priority != PRIORITY_MID_HIGH) &&
            (priority != PRIORITY_HIGH)) {
        printk("set_channel_priority: bad priority: 0x%x\n", priority);
    }
#endif