/*
 * Copyright © 2006-2007 Intel Corporation
 *
 * 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, sublicense,
 * 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 above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 *
 * Authors:
 *      Eric Anholt <eric@anholt.net>
 */

#include <linux/dmi.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <drm/drmP.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_crtc.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_edid.h>
#include "intel_drv.h"
#include <drm/i915_drm.h>
#include "i915_drv.h"

/* Here's the desired hotplug mode */
#define ADPA_HOTPLUG_BITS (ADPA_CRT_HOTPLUG_PERIOD_128 |                \
                           ADPA_CRT_HOTPLUG_WARMUP_10MS |               \
                           ADPA_CRT_HOTPLUG_SAMPLE_4S |                 \
                           ADPA_CRT_HOTPLUG_VOLTAGE_50 |                \
                           ADPA_CRT_HOTPLUG_VOLREF_325MV |              \
                           ADPA_CRT_HOTPLUG_ENABLE)

struct intel_crt {
        struct intel_encoder base;
        /* DPMS state is stored in the connector, which we need in the
         * encoder's enable/disable callbacks */
        struct intel_connector *connector;
        bool force_hotplug_required;
        i915_reg_t adpa_reg;
};

static struct intel_crt *intel_encoder_to_crt(struct intel_encoder *encoder)
{
        return container_of(encoder, struct intel_crt, base);
}

static struct intel_crt *intel_attached_crt(struct drm_connector *connector)
{
        return intel_encoder_to_crt(intel_attached_encoder(connector));
}

static bool intel_crt_get_hw_state(struct intel_encoder *encoder,
                                   enum pipe *pipe)
{
        struct drm_device *dev = encoder->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_crt *crt = intel_encoder_to_crt(encoder);
        enum intel_display_power_domain power_domain;
        u32 tmp;
        bool ret;

        power_domain = intel_display_port_power_domain(encoder);
        if (!intel_display_power_get_if_enabled(dev_priv, power_domain))
                return false;

        ret = false;

        tmp = I915_READ(crt->adpa_reg);

        if (!(tmp & ADPA_DAC_ENABLE))
                goto out;

        if (HAS_PCH_CPT(dev))
                *pipe = PORT_TO_PIPE_CPT(tmp);
        else
                *pipe = PORT_TO_PIPE(tmp);

        ret = true;
out:
        intel_display_power_put(dev_priv, power_domain);

        return ret;
}

static unsigned int intel_crt_get_flags(struct intel_encoder *encoder)
{
        struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
        struct intel_crt *crt = intel_encoder_to_crt(encoder);
        u32 tmp, flags = 0;

        tmp = I915_READ(crt->adpa_reg);

        if (tmp & ADPA_HSYNC_ACTIVE_HIGH)
                flags |= DRM_MODE_FLAG_PHSYNC;
        else
                flags |= DRM_MODE_FLAG_NHSYNC;

        if (tmp & ADPA_VSYNC_ACTIVE_HIGH)
                flags |= DRM_MODE_FLAG_PVSYNC;
        else
                flags |= DRM_MODE_FLAG_NVSYNC;

        return flags;
}

static void intel_crt_get_config(struct intel_encoder *encoder,
                                 struct intel_crtc_state *pipe_config)
{
        pipe_config->base.adjusted_mode.flags |= intel_crt_get_flags(encoder);

        pipe_config->base.adjusted_mode.crtc_clock = pipe_config->port_clock;
}

static void hsw_crt_get_config(struct intel_encoder *encoder,
                               struct intel_crtc_state *pipe_config)
{
        struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);

        intel_ddi_get_config(encoder, pipe_config);

        pipe_config->base.adjusted_mode.flags &= ~(DRM_MODE_FLAG_PHSYNC |
                                              DRM_MODE_FLAG_NHSYNC |
                                              DRM_MODE_FLAG_PVSYNC |
                                              DRM_MODE_FLAG_NVSYNC);
        pipe_config->base.adjusted_mode.flags |= intel_crt_get_flags(encoder);

        pipe_config->base.adjusted_mode.crtc_clock = lpt_get_iclkip(dev_priv);
}

/* Note: The caller is required to filter out dpms modes not supported by the
 * platform. */
static void intel_crt_set_dpms(struct intel_encoder *encoder, int mode)
{
        struct drm_device *dev = encoder->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_crt *crt = intel_encoder_to_crt(encoder);
        struct intel_crtc *crtc = to_intel_crtc(encoder->base.crtc);
        const struct drm_display_mode *adjusted_mode = &crtc->config->base.adjusted_mode;
        u32 adpa;

        if (INTEL_INFO(dev)->gen >= 5)
                adpa = ADPA_HOTPLUG_BITS;
        else
                adpa = 0;

        if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
                adpa |= ADPA_HSYNC_ACTIVE_HIGH;
        if (adjusted_mode->flags & DRM_MODE_FLAG_PVSYNC)
                adpa |= ADPA_VSYNC_ACTIVE_HIGH;

        /* For CPT allow 3 pipe config, for others just use A or B */
        if (HAS_PCH_LPT(dev))
                ; /* Those bits don't exist here */
        else if (HAS_PCH_CPT(dev))
                adpa |= PORT_TRANS_SEL_CPT(crtc->pipe);
        else if (crtc->pipe == 0)
                adpa |= ADPA_PIPE_A_SELECT;
        else
                adpa |= ADPA_PIPE_B_SELECT;

        if (!HAS_PCH_SPLIT(dev))
                I915_WRITE(BCLRPAT(crtc->pipe), 0);

        switch (mode) {
        case DRM_MODE_DPMS_ON:
                adpa |= ADPA_DAC_ENABLE;
                break;
        case DRM_MODE_DPMS_STANDBY:
                adpa |= ADPA_DAC_ENABLE | ADPA_HSYNC_CNTL_DISABLE;
                break;
        case DRM_MODE_DPMS_SUSPEND:
                adpa |= ADPA_DAC_ENABLE | ADPA_VSYNC_CNTL_DISABLE;
                break;
        case DRM_MODE_DPMS_OFF:
                adpa |= ADPA_HSYNC_CNTL_DISABLE | ADPA_VSYNC_CNTL_DISABLE;
                break;
        }

        I915_WRITE(crt->adpa_reg, adpa);
}

static void intel_disable_crt(struct intel_encoder *encoder)
{
        intel_crt_set_dpms(encoder, DRM_MODE_DPMS_OFF);
}

static void pch_disable_crt(struct intel_encoder *encoder)
{
}

static void pch_post_disable_crt(struct intel_encoder *encoder)
{
        intel_disable_crt(encoder);
}

static void intel_enable_crt(struct intel_encoder *encoder)
{
        intel_crt_set_dpms(encoder, DRM_MODE_DPMS_ON);
}

static enum drm_mode_status
intel_crt_mode_valid(struct drm_connector *connector,
                     struct drm_display_mode *mode)
{
        struct drm_device *dev = connector->dev;
        int max_dotclk = to_i915(dev)->max_dotclk_freq;
        int max_clock;

        if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
                return MODE_NO_DBLESCAN;

        if (mode->clock < 25000)
                return MODE_CLOCK_LOW;

        if (HAS_PCH_LPT(dev))
                max_clock = 180000;
        else if (IS_VALLEYVIEW(dev))
                /*
                 * 270 MHz due to current DPLL limits,
                 * DAC limit supposedly 355 MHz.
                 */
                max_clock = 270000;
        else if (IS_GEN3(dev) || IS_GEN4(dev))
                max_clock = 400000;
        else
                max_clock = 350000;
        if (mode->clock > max_clock)
                return MODE_CLOCK_HIGH;

        if (mode->clock > max_dotclk)
                return MODE_CLOCK_HIGH;

        /* The FDI receiver on LPT only supports 8bpc and only has 2 lanes. */
        if (HAS_PCH_LPT(dev) &&
            (ironlake_get_lanes_required(mode->clock, 270000, 24) > 2))
                return MODE_CLOCK_HIGH;

        return MODE_OK;
}

static bool intel_crt_compute_config(struct intel_encoder *encoder,
                                     struct intel_crtc_state *pipe_config)
{
        struct drm_device *dev = encoder->base.dev;

        if (HAS_PCH_SPLIT(dev))
                pipe_config->has_pch_encoder = true;

        /* LPT FDI RX only supports 8bpc. */
        if (HAS_PCH_LPT(dev)) {
                if (pipe_config->bw_constrained && pipe_config->pipe_bpp < 24) {
                        DRM_DEBUG_KMS("LPT only supports 24bpp\n");
                        return false;
                }

                pipe_config->pipe_bpp = 24;
        }

        /* FDI must always be 2.7 GHz */
        if (HAS_DDI(dev))
                pipe_config->port_clock = 135000 * 2;

        return true;
}

static bool intel_ironlake_crt_detect_hotplug(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct intel_crt *crt = intel_attached_crt(connector);
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 adpa;
        bool ret;

        /* The first time through, trigger an explicit detection cycle */
        if (crt->force_hotplug_required) {
                bool turn_off_dac = HAS_PCH_SPLIT(dev);
                u32 save_adpa;

                crt->force_hotplug_required = 0;

                save_adpa = adpa = I915_READ(crt->adpa_reg);
                DRM_DEBUG_KMS("trigger hotplug detect cycle: adpa=0x%x\n", adpa);

                adpa |= ADPA_CRT_HOTPLUG_FORCE_TRIGGER;
                if (turn_off_dac)
                        adpa &= ~ADPA_DAC_ENABLE;

                I915_WRITE(crt->adpa_reg, adpa);

                if (wait_for((I915_READ(crt->adpa_reg) & ADPA_CRT_HOTPLUG_FORCE_TRIGGER) == 0,
                             1000))
                        DRM_DEBUG_KMS("timed out waiting for FORCE_TRIGGER");

                if (turn_off_dac) {
                        I915_WRITE(crt->adpa_reg, save_adpa);
                        POSTING_READ(crt->adpa_reg);
                }
        }

        /* Check the status to see if both blue and green are on now */
        adpa = I915_READ(crt->adpa_reg);
        if ((adpa & ADPA_CRT_HOTPLUG_MONITOR_MASK) != 0)
                ret = true;
        else
                ret = false;
        DRM_DEBUG_KMS("ironlake hotplug adpa=0x%x, result %d\n", adpa, ret);

        return ret;
}

static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct intel_crt *crt = intel_attached_crt(connector);
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 adpa;
        bool ret;
        u32 save_adpa;

        save_adpa = adpa = I915_READ(crt->adpa_reg);
        DRM_DEBUG_KMS("trigger hotplug detect cycle: adpa=0x%x\n", adpa);

        adpa |= ADPA_CRT_HOTPLUG_FORCE_TRIGGER;

        I915_WRITE(crt->adpa_reg, adpa);

        if (wait_for((I915_READ(crt->adpa_reg) & ADPA_CRT_HOTPLUG_FORCE_TRIGGER) == 0,
                     1000)) {
                DRM_DEBUG_KMS("timed out waiting for FORCE_TRIGGER");
                I915_WRITE(crt->adpa_reg, save_adpa);
        }

        /* Check the status to see if both blue and green are on now */
        adpa = I915_READ(crt->adpa_reg);
        if ((adpa & ADPA_CRT_HOTPLUG_MONITOR_MASK) != 0)
                ret = true;
        else
                ret = false;

        DRM_DEBUG_KMS("valleyview hotplug adpa=0x%x, result %d\n", adpa, ret);

        return ret;
}

/**
 * Uses CRT_HOTPLUG_EN and CRT_HOTPLUG_STAT to detect CRT presence.
 *
 * Not for i915G/i915GM
 *
 * \return true if CRT is connected.
 * \return false if CRT is disconnected.
 */
static bool intel_crt_detect_hotplug(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 stat;
        bool ret = false;
        int i, tries = 0;

        if (HAS_PCH_SPLIT(dev))
                return intel_ironlake_crt_detect_hotplug(connector);

        if (IS_VALLEYVIEW(dev))
                return valleyview_crt_detect_hotplug(connector);

        /*
         * On 4 series desktop, CRT detect sequence need to be done twice
         * to get a reliable result.
         */

        if (IS_G4X(dev) && !IS_GM45(dev))
                tries = 2;
        else
                tries = 1;

        for (i = 0; i < tries ; i++) {
                /* turn on the FORCE_DETECT */
                i915_hotplug_interrupt_update(dev_priv,
                                              CRT_HOTPLUG_FORCE_DETECT,
                                              CRT_HOTPLUG_FORCE_DETECT);
                /* wait for FORCE_DETECT to go off */
                if (wait_for((I915_READ(PORT_HOTPLUG_EN) &
                              CRT_HOTPLUG_FORCE_DETECT) == 0,
                             1000))
                        DRM_DEBUG_KMS("timed out waiting for FORCE_DETECT to go off");
        }

        stat = I915_READ(PORT_HOTPLUG_STAT);
        if ((stat & CRT_HOTPLUG_MONITOR_MASK) != CRT_HOTPLUG_MONITOR_NONE)
                ret = true;

        /* clear the interrupt we just generated, if any */
        I915_WRITE(PORT_HOTPLUG_STAT, CRT_HOTPLUG_INT_STATUS);

        i915_hotplug_interrupt_update(dev_priv, CRT_HOTPLUG_FORCE_DETECT, 0);

        return ret;
}

static struct edid *intel_crt_get_edid(struct drm_connector *connector,
                                struct i2c_adapter *i2c)
{
        struct edid *edid;

        edid = drm_get_edid(connector, i2c);

        if (!edid && !intel_gmbus_is_forced_bit(i2c)) {
                DRM_DEBUG_KMS("CRT GMBUS EDID read failed, retry using GPIO bit-banging\n");
                intel_gmbus_force_bit(i2c, true);
                edid = drm_get_edid(connector, i2c);
                intel_gmbus_force_bit(i2c, false);
        }

        return edid;
}

/* local version of intel_ddc_get_modes() to use intel_crt_get_edid() */
static int intel_crt_ddc_get_modes(struct drm_connector *connector,
                                struct i2c_adapter *adapter)
{
        struct edid *edid;
        int ret;

        edid = intel_crt_get_edid(connector, adapter);
        if (!edid)
                return 0;

        ret = intel_connector_update_modes(connector, edid);
        kfree(edid);

        return ret;
}

static bool intel_crt_detect_ddc(struct drm_connector *connector)
{
        struct intel_crt *crt = intel_attached_crt(connector);
        struct drm_i915_private *dev_priv = crt->base.base.dev->dev_private;
        struct edid *edid;
        struct i2c_adapter *i2c;

        BUG_ON(crt->base.type != INTEL_OUTPUT_ANALOG);

        i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->vbt.crt_ddc_pin);
        edid = intel_crt_get_edid(connector, i2c);

        if (edid) {
                bool is_digital = edid->input & DRM_EDID_INPUT_DIGITAL;

                /*
                 * This may be a DVI-I connector with a shared DDC
                 * link between analog and digital outputs, so we
                 * have to check the EDID input spec of the attached device.
                 */
                if (!is_digital) {
                        DRM_DEBUG_KMS("CRT detected via DDC:0x50 [EDID]\n");
                        return true;
                }

                DRM_DEBUG_KMS("CRT not detected via DDC:0x50 [EDID reports a digital panel]\n");
        } else {
                DRM_DEBUG_KMS("CRT not detected via DDC:0x50 [no valid EDID found]\n");
        }

        kfree(edid);

        return false;
}

static enum drm_connector_status
intel_crt_load_detect(struct intel_crt *crt, uint32_t pipe)
{
        struct drm_device *dev = crt->base.base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        uint32_t save_bclrpat;
        uint32_t save_vtotal;
        uint32_t vtotal, vactive;
        uint32_t vsample;
        uint32_t vblank, vblank_start, vblank_end;
        uint32_t dsl;
        i915_reg_t bclrpat_reg, vtotal_reg,
                vblank_reg, vsync_reg, pipeconf_reg, pipe_dsl_reg;
        uint8_t st00;
        enum drm_connector_status status;

        DRM_DEBUG_KMS("starting load-detect on CRT\n");

        bclrpat_reg = BCLRPAT(pipe);
        vtotal_reg = VTOTAL(pipe);
        vblank_reg = VBLANK(pipe);
        vsync_reg = VSYNC(pipe);
        pipeconf_reg = PIPECONF(pipe);
        pipe_dsl_reg = PIPEDSL(pipe);

        save_bclrpat = I915_READ(bclrpat_reg);
        save_vtotal = I915_READ(vtotal_reg);
        vblank = I915_READ(vblank_reg);

        vtotal = ((save_vtotal >> 16) & 0xfff) + 1;
        vactive = (save_vtotal & 0x7ff) + 1;

        vblank_start = (vblank & 0xfff) + 1;
        vblank_end = ((vblank >> 16) & 0xfff) + 1;

        /* Set the border color to purple. */
        I915_WRITE(bclrpat_reg, 0x500050);

        if (!IS_GEN2(dev)) {
                uint32_t pipeconf = I915_READ(pipeconf_reg);
                I915_WRITE(pipeconf_reg, pipeconf | PIPECONF_FORCE_BORDER);
                POSTING_READ(pipeconf_reg);
                /* Wait for next Vblank to substitue
                 * border color for Color info */
                intel_wait_for_vblank(dev, pipe);
                st00 = I915_READ8(_VGA_MSR_WRITE);
                status = ((st00 & (1 << 4)) != 0) ?
                        connector_status_connected :
                        connector_status_disconnected;

                I915_WRITE(pipeconf_reg, pipeconf);
        } else {
                bool restore_vblank = false;
                int count, detect;

                /*
                * If there isn't any border, add some.
                * Yes, this will flicker
                */
                if (vblank_start <= vactive && vblank_end >= vtotal) {
                        uint32_t vsync = I915_READ(vsync_reg);
                        uint32_t vsync_start = (vsync & 0xffff) + 1;

                        vblank_start = vsync_start;
                        I915_WRITE(vblank_reg,
                                   (vblank_start - 1) |
                                   ((vblank_end - 1) << 16));
                        restore_vblank = true;
                }
                /* sample in the vertical border, selecting the larger one */
                if (vblank_start - vactive >= vtotal - vblank_end)
                        vsample = (vblank_start + vactive) >> 1;
                else
                        vsample = (vtotal + vblank_end) >> 1;

                /*
                 * Wait for the border to be displayed
                 */
                while (I915_READ(pipe_dsl_reg) >= vactive)
                        ;
                while ((dsl = I915_READ(pipe_dsl_reg)) <= vsample)
                        ;
                /*
                 * Watch ST00 for an entire scanline
                 */
                detect = 0;
                count = 0;
                do {
                        count++;
                        /* Read the ST00 VGA status register */
                        st00 = I915_READ8(_VGA_MSR_WRITE);
                        if (st00 & (1 << 4))
                                detect++;
                } while ((I915_READ(pipe_dsl_reg) == dsl));

                /* restore vblank if necessary */
                if (restore_vblank)
                        I915_WRITE(vblank_reg, vblank);
                /*
                 * If more than 3/4 of the scanline detected a monitor,
                 * then it is assumed to be present. This works even on i830,
                 * where there isn't any way to force the border color across
                 * the screen
                 */
                status = detect * 4 > count * 3 ?
                         connector_status_connected :
                         connector_status_disconnected;
        }

        /* Restore previous settings */
        I915_WRITE(bclrpat_reg, save_bclrpat);

        return status;
}

static enum drm_connector_status
intel_crt_detect(struct drm_connector *connector, bool force)
{
        struct drm_device *dev = connector->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_crt *crt = intel_attached_crt(connector);
        struct intel_encoder *intel_encoder = &crt->base;
        enum intel_display_power_domain power_domain;
        enum drm_connector_status status;
        struct intel_load_detect_pipe tmp;
        struct drm_modeset_acquire_ctx ctx;

        DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
                      connector->base.id, connector->name,
                      force);

        power_domain = intel_display_port_power_domain(intel_encoder);
        intel_display_power_get(dev_priv, power_domain);

        if (I915_HAS_HOTPLUG(dev)) {
                /* We can not rely on the HPD pin always being correctly wired
                 * up, for example many KVM do not pass it through, and so
                 * only trust an assertion that the monitor is connected.
                 */
                if (intel_crt_detect_hotplug(connector)) {
                        DRM_DEBUG_KMS("CRT detected via hotplug\n");
                        status = connector_status_connected;
                        goto out;
                } else
                        DRM_DEBUG_KMS("CRT not detected via hotplug\n");
        }

        if (intel_crt_detect_ddc(connector)) {
                status = connector_status_connected;
                goto out;
        }

        /* Load detection is broken on HPD capable machines. Whoever wants a
         * broken monitor (without edid) to work behind a broken kvm (that fails
         * to have the right resistors for HP detection) needs to fix this up.
         * For now just bail out. */
        if (I915_HAS_HOTPLUG(dev) && !i915.load_detect_test) {
                status = connector_status_disconnected;
                goto out;
        }

        if (!force) {
                status = connector->status;
                goto out;
        }

        drm_modeset_acquire_init(&ctx, 0);

        /* for pre-945g platforms use load detect */
        if (intel_get_load_detect_pipe(connector, NULL, &tmp, &ctx)) {
                if (intel_crt_detect_ddc(connector))
                        status = connector_status_connected;
                else if (INTEL_INFO(dev)->gen < 4)
                        status = intel_crt_load_detect(crt,
                                to_intel_crtc(connector->state->crtc)->pipe);
                else if (i915.load_detect_test)
                        status = connector_status_disconnected;
                else
                        status = connector_status_unknown;
                intel_release_load_detect_pipe(connector, &tmp, &ctx);
        } else
                status = connector_status_unknown;

        drm_modeset_drop_locks(&ctx);
        drm_modeset_acquire_fini(&ctx);

out:
        intel_display_power_put(dev_priv, power_domain);
        return status;
}

static void intel_crt_destroy(struct drm_connector *connector)
{
        drm_connector_cleanup(connector);
        kfree(connector);
}

static int intel_crt_get_modes(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_crt *crt = intel_attached_crt(connector);
        struct intel_encoder *intel_encoder = &crt->base;
        enum intel_display_power_domain power_domain;
        int ret;
        struct i2c_adapter *i2c;

        power_domain = intel_display_port_power_domain(intel_encoder);
        intel_display_power_get(dev_priv, power_domain);

        i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->vbt.crt_ddc_pin);
        ret = intel_crt_ddc_get_modes(connector, i2c);
        if (ret || !IS_G4X(dev))
                goto out;

        /* Try to probe digital port for output in DVI-I -> VGA mode. */
        i2c = intel_gmbus_get_adapter(dev_priv, GMBUS_PIN_DPB);
        ret = intel_crt_ddc_get_modes(connector, i2c);

out:
        intel_display_power_put(dev_priv, power_domain);

        return ret;
}

static int intel_crt_set_property(struct drm_connector *connector,
                                  struct drm_property *property,
                                  uint64_t value)
{
        return 0;
}

static void intel_crt_reset(struct drm_connector *connector)
{
        struct drm_device *dev = connector->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_crt *crt = intel_attached_crt(connector);

        if (INTEL_INFO(dev)->gen >= 5) {
                u32 adpa;

                adpa = I915_READ(crt->adpa_reg);
                adpa &= ~ADPA_CRT_HOTPLUG_MASK;
                adpa |= ADPA_HOTPLUG_BITS;
                I915_WRITE(crt->adpa_reg, adpa);
                POSTING_READ(crt->adpa_reg);

                DRM_DEBUG_KMS("crt adpa set to 0x%x\n", adpa);
                crt->force_hotplug_required = 1;
        }

}

/*
 * Routines for controlling stuff on the analog port
 */

static const struct drm_connector_funcs intel_crt_connector_funcs = {
        .reset = intel_crt_reset,
        .dpms = drm_atomic_helper_connector_dpms,
        .detect = intel_crt_detect,
        .fill_modes = drm_helper_probe_single_connector_modes,
        .destroy = intel_crt_destroy,
        .set_property = intel_crt_set_property,
        .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
        .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
        .atomic_get_property = intel_connector_atomic_get_property,
};

static const struct drm_connector_helper_funcs intel_crt_connector_helper_funcs = {
        .mode_valid = intel_crt_mode_valid,
        .get_modes = intel_crt_get_modes,
        .best_encoder = intel_best_encoder,
};

static const struct drm_encoder_funcs intel_crt_enc_funcs = {
        .destroy = intel_encoder_destroy,
};

static int intel_no_crt_dmi_callback(const struct dmi_system_id *id)
{
        DRM_INFO("Skipping CRT initialization for %s\n", id->ident);
        return 1;
}

static const struct dmi_system_id intel_no_crt[] = {
        {
                .callback = intel_no_crt_dmi_callback,
                .ident = "ACER ZGB",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "ACER"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "ZGB"),
                },
        },
        {
                .callback = intel_no_crt_dmi_callback,
                .ident = "DELL XPS 8700",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "XPS 8700"),
                },
        },
        { }
};

void intel_crt_init(struct drm_device *dev)
{
        struct drm_connector *connector;
        struct intel_crt *crt;
        struct intel_connector *intel_connector;
        struct drm_i915_private *dev_priv = dev->dev_private;
        i915_reg_t adpa_reg;
        u32 adpa;

        /* Skip machines without VGA that falsely report hotplug events */
        if (dmi_check_system(intel_no_crt))
                return;

        if (HAS_PCH_SPLIT(dev))
                adpa_reg = PCH_ADPA;
        else if (IS_VALLEYVIEW(dev))
                adpa_reg = VLV_ADPA;
        else
                adpa_reg = ADPA;

        adpa = I915_READ(adpa_reg);
        if ((adpa & ADPA_DAC_ENABLE) == 0) {
                /*
                 * On some machines (some IVB at least) CRT can be
                 * fused off, but there's no known fuse bit to
                 * indicate that. On these machine the ADPA register
                 * works normally, except the DAC enable bit won't
                 * take. So the only way to tell is attempt to enable
                 * it and see what happens.
                 */
                I915_WRITE(adpa_reg, adpa | ADPA_DAC_ENABLE |
                           ADPA_HSYNC_CNTL_DISABLE | ADPA_VSYNC_CNTL_DISABLE);
                if ((I915_READ(adpa_reg) & ADPA_DAC_ENABLE) == 0)
                        return;
                I915_WRITE(adpa_reg, adpa);
        }

        crt = kzalloc(sizeof(struct intel_crt), GFP_KERNEL);
        if (!crt)
                return;

        intel_connector = intel_connector_alloc();
        if (!intel_connector) {
                kfree(crt);
                return;
        }

        connector = &intel_connector->base;
        crt->connector = intel_connector;
        drm_connector_init(dev, &intel_connector->base,
                           &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA);

        drm_encoder_init(dev, &crt->base.base, &intel_crt_enc_funcs,
                         DRM_MODE_ENCODER_DAC, NULL);

        intel_connector_attach_encoder(intel_connector, &crt->base);

        crt->base.type = INTEL_OUTPUT_ANALOG;
        crt->base.cloneable = (1 << INTEL_OUTPUT_DVO) | (1 << INTEL_OUTPUT_HDMI);
        if (IS_I830(dev))
                crt->base.crtc_mask = (1 << 0);
        else
                crt->base.crtc_mask = (1 << 0) | (1 << 1) | (1 << 2);

        if (IS_GEN2(dev))
                connector->interlace_allowed = 0;
        else
                connector->interlace_allowed = 1;
        connector->doublescan_allowed = 0;

        crt->adpa_reg = adpa_reg;

        crt->base.compute_config = intel_crt_compute_config;
        if (HAS_PCH_SPLIT(dev)) {
                crt->base.disable = pch_disable_crt;
                crt->base.post_disable = pch_post_disable_crt;
        } else {
                crt->base.disable = intel_disable_crt;
        }
        crt->base.enable = intel_enable_crt;
        if (I915_HAS_HOTPLUG(dev))
                crt->base.hpd_pin = HPD_CRT;
        if (HAS_DDI(dev)) {
                crt->base.get_config = hsw_crt_get_config;
                crt->base.get_hw_state = intel_ddi_get_hw_state;
        } else {
                crt->base.get_config = intel_crt_get_config;
                crt->base.get_hw_state = intel_crt_get_hw_state;
        }
        intel_connector->get_hw_state = intel_connector_get_hw_state;
        intel_connector->unregister = intel_connector_unregister;

        drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs);

        drm_connector_register(connector);

        if (!I915_HAS_HOTPLUG(dev))
                intel_connector->polled = DRM_CONNECTOR_POLL_CONNECT;

        /*
         * Configure the automatic hotplug detection stuff
         */
        crt->force_hotplug_required = 0;

        /*
         * TODO: find a proper way to discover whether we need to set the the
         * polarity and link reversal bits or not, instead of relying on the
         * BIOS.
         */
        if (HAS_PCH_LPT(dev)) {
                u32 fdi_config = FDI_RX_POLARITY_REVERSED_LPT |
                                 FDI_RX_LINK_REVERSAL_OVERRIDE;

                dev_priv->fdi_rx_config = I915_READ(FDI_RX_CTL(PIPE_A)) & fdi_config;
        }

        intel_crt_reset(connector);
}