/*
 * Copyright 2012 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 */
/*
 * Authors: Dave Airlie <airlied@redhat.com>
 */

#include <linux/i2c-algo-bit.h>
#include <linux/i2c.h>
#include <linux/pci.h>

#include <drm/drm_managed.h>

#include "mgag200_ddc.h"
#include "mgag200_drv.h"

struct mgag200_ddc {
        struct mga_device *mdev;

        int data;
        int clock;

        struct i2c_algo_bit_data bit;
        struct i2c_adapter adapter;
};

static int mga_i2c_read_gpio(struct mga_device *mdev)
{
        WREG8(DAC_INDEX, MGA1064_GEN_IO_DATA);
        return RREG8(DAC_DATA);
}

static void mga_i2c_set_gpio(struct mga_device *mdev, int mask, int val)
{
        int tmp;

        WREG8(DAC_INDEX, MGA1064_GEN_IO_CTL);
        tmp = (RREG8(DAC_DATA) & mask) | val;
        WREG_DAC(MGA1064_GEN_IO_CTL, tmp);
        WREG_DAC(MGA1064_GEN_IO_DATA, 0);
}

static inline void mga_i2c_set(struct mga_device *mdev, int mask, int state)
{
        if (state)
                state = 0;
        else
                state = mask;
        mga_i2c_set_gpio(mdev, ~mask, state);
}

static void mgag200_ddc_algo_bit_data_setsda(void *data, int state)
{
        struct mgag200_ddc *ddc = data;

        mga_i2c_set(ddc->mdev, ddc->data, state);
}

static void mgag200_ddc_algo_bit_data_setscl(void *data, int state)
{
        struct mgag200_ddc *ddc = data;

        mga_i2c_set(ddc->mdev, ddc->clock, state);
}

static int mgag200_ddc_algo_bit_data_getsda(void *data)
{
        struct mgag200_ddc *ddc = data;

        return (mga_i2c_read_gpio(ddc->mdev) & ddc->data) ? 1 : 0;
}

static int mgag200_ddc_algo_bit_data_getscl(void *data)
{
        struct mgag200_ddc *ddc = data;

        return (mga_i2c_read_gpio(ddc->mdev) & ddc->clock) ? 1 : 0;
}

static int mgag200_ddc_algo_bit_data_pre_xfer(struct i2c_adapter *adapter)
{
        struct mgag200_ddc *ddc = i2c_get_adapdata(adapter);
        struct mga_device *mdev = ddc->mdev;

        /*
         * Protect access to I/O registers from concurrent modesetting
         * by acquiring the I/O-register lock.
         */
        mutex_lock(&mdev->rmmio_lock);

        return 0;
}

static void mgag200_ddc_algo_bit_data_post_xfer(struct i2c_adapter *adapter)
{
        struct mgag200_ddc *ddc = i2c_get_adapdata(adapter);
        struct mga_device *mdev = ddc->mdev;

        mutex_unlock(&mdev->rmmio_lock);
}

static void mgag200_ddc_release(struct drm_device *dev, void *res)
{
        struct mgag200_ddc *ddc = res;

        i2c_del_adapter(&ddc->adapter);
}

struct i2c_adapter *mgag200_ddc_create(struct mga_device *mdev)
{
        struct drm_device *dev = &mdev->base;
        const struct mgag200_device_info *info = mdev->info;
        struct mgag200_ddc *ddc;
        struct i2c_algo_bit_data *bit;
        struct i2c_adapter *adapter;
        int ret;

        ddc = drmm_kzalloc(dev, sizeof(*ddc), GFP_KERNEL);
        if (!ddc)
                return ERR_PTR(-ENOMEM);

        WREG_DAC(MGA1064_GEN_IO_CTL2, 1);
        WREG_DAC(MGA1064_GEN_IO_DATA, 0xff);
        WREG_DAC(MGA1064_GEN_IO_CTL, 0);

        ddc->mdev = mdev;
        ddc->data = BIT(info->i2c.data_bit);
        ddc->clock = BIT(info->i2c.clock_bit);

        bit = &ddc->bit;
        bit->data = ddc;
        bit->setsda = mgag200_ddc_algo_bit_data_setsda;
        bit->setscl = mgag200_ddc_algo_bit_data_setscl;
        bit->getsda = mgag200_ddc_algo_bit_data_getsda;
        bit->getscl = mgag200_ddc_algo_bit_data_getscl;
        bit->pre_xfer = mgag200_ddc_algo_bit_data_pre_xfer;
        bit->post_xfer = mgag200_ddc_algo_bit_data_post_xfer;
        bit->udelay = 10;
        bit->timeout = usecs_to_jiffies(2200);

        adapter = &ddc->adapter;
        adapter->owner = THIS_MODULE;
        adapter->algo_data = bit;
        adapter->dev.parent = dev->dev;
        snprintf(adapter->name, sizeof(adapter->name), "Matrox DDC bus");
        i2c_set_adapdata(adapter, ddc);

        ret = i2c_bit_add_bus(adapter);
        if (ret)
                return ERR_PTR(ret);

        ret = drmm_add_action_or_reset(dev, mgag200_ddc_release, ddc);
        if (ret)
                return ERR_PTR(ret);

        return adapter;
}