// SPDX-License-Identifier: GPL-2.0-only

#include <linux/delay.h>
#include <linux/iopoll.h>

#include <drm/drm_atomic_helper.h>
#include <drm/drm_edid.h>
#include <drm/drm_managed.h>
#include <drm/drm_probe_helper.h>

#include "mgag200_drv.h"

void mgag200_bmc_stop_scanout(struct mga_device *mdev)
{
        u8 tmp;
        int ret;

        /*
         * 1 - The first step is to inform the BMC of an upcoming mode
         * change. We are putting the misc<0> to output.
         */

        WREG8(DAC_INDEX, MGA1064_GEN_IO_CTL);
        tmp = RREG8(DAC_DATA);
        tmp |= 0x10;
        WREG_DAC(MGA1064_GEN_IO_CTL, tmp);

        /* we are putting a 1 on the misc<0> line */
        WREG8(DAC_INDEX, MGA1064_GEN_IO_DATA);
        tmp = RREG8(DAC_DATA);
        tmp |= 0x10;
        WREG_DAC(MGA1064_GEN_IO_DATA, tmp);

        /*
         * 2- Second step to mask any further scan request. This is
         * done by asserting the remfreqmsk bit (XSPAREREG<7>)
         */

        WREG8(DAC_INDEX, MGA1064_SPAREREG);
        tmp = RREG8(DAC_DATA);
        tmp |= 0x80;
        WREG_DAC(MGA1064_SPAREREG, tmp);

        /*
         * 3a- The third step is to verify if there is an active scan.
         * We are waiting for a 0 on remhsyncsts (<XSPAREREG<0>).
         */
        ret = read_poll_timeout(RREG_DAC, tmp, !(tmp & 0x1),
                                1000, 300000, false,
                                MGA1064_SPAREREG);
        if (ret == -ETIMEDOUT)
                return;

        /*
         * 3b- This step occurs only if the remote BMC is actually
         * scanning. We are waiting for the end of the frame which is
         * a 1 on remvsyncsts (XSPAREREG<1>)
         */
        (void)read_poll_timeout(RREG_DAC, tmp, (tmp & 0x2),
                                1000, 300000, false,
                                MGA1064_SPAREREG);
}

void mgag200_bmc_start_scanout(struct mga_device *mdev)
{
        u8 tmp;

        /* Assert rstlvl2 */
        WREG8(DAC_INDEX, MGA1064_REMHEADCTL2);
        tmp = RREG8(DAC_DATA);
        tmp |= 0x8;
        WREG8(DAC_DATA, tmp);

        udelay(10);

        /* Deassert rstlvl2 */
        tmp &= ~0x08;
        WREG8(DAC_INDEX, MGA1064_REMHEADCTL2);
        WREG8(DAC_DATA, tmp);

        /* Remove mask of scan request */
        WREG8(DAC_INDEX, MGA1064_SPAREREG);
        tmp = RREG8(DAC_DATA);
        tmp &= ~0x80;
        WREG8(DAC_DATA, tmp);

        /* Put back a 0 on the misc<0> line */
        WREG8(DAC_INDEX, MGA1064_GEN_IO_DATA);
        tmp = RREG8(DAC_DATA);
        tmp &= ~0x10;
        WREG_DAC(MGA1064_GEN_IO_DATA, tmp);
}