/*
 * Copyright © 2006-2010 Intel Corporation
 * Copyright (c) 2006 Dave Airlie <airlied@linux.ie>
 *
 * 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>
 *      Dave Airlie <airlied@linux.ie>
 *      Jesse Barnes <jesse.barnes@intel.com>
 *      Chris Wilson <chris@chris-wilson.co.uk>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/pwm.h>
#include "intel_drv.h"

#define CRC_PMIC_PWM_PERIOD_NS  21333

void
intel_fixed_panel_mode(const struct drm_display_mode *fixed_mode,
                       struct drm_display_mode *adjusted_mode)
{
        drm_mode_copy(adjusted_mode, fixed_mode);

        drm_mode_set_crtcinfo(adjusted_mode, 0);
}

/**
 * intel_find_panel_downclock - find the reduced downclock for LVDS in EDID
 * @dev_priv: i915 device instance
 * @fixed_mode : panel native mode
 * @connector: LVDS/eDP connector
 *
 * Return downclock_avail
 * Find the reduced downclock for LVDS/eDP in EDID.
 */
struct drm_display_mode *
intel_find_panel_downclock(struct drm_i915_private *dev_priv,
                        struct drm_display_mode *fixed_mode,
                        struct drm_connector *connector)
{
        struct drm_display_mode *scan, *tmp_mode;
        int temp_downclock;

        temp_downclock = fixed_mode->clock;
        tmp_mode = NULL;

        list_for_each_entry(scan, &connector->probed_modes, head) {
                /*
                 * If one mode has the same resolution with the fixed_panel
                 * mode while they have the different refresh rate, it means
                 * that the reduced downclock is found. In such
                 * case we can set the different FPx0/1 to dynamically select
                 * between low and high frequency.
                 */
                if (scan->hdisplay == fixed_mode->hdisplay &&
                    scan->hsync_start == fixed_mode->hsync_start &&
                    scan->hsync_end == fixed_mode->hsync_end &&
                    scan->htotal == fixed_mode->htotal &&
                    scan->vdisplay == fixed_mode->vdisplay &&
                    scan->vsync_start == fixed_mode->vsync_start &&
                    scan->vsync_end == fixed_mode->vsync_end &&
                    scan->vtotal == fixed_mode->vtotal) {
                        if (scan->clock < temp_downclock) {
                                /*
                                 * The downclock is already found. But we
                                 * expect to find the lower downclock.
                                 */
                                temp_downclock = scan->clock;
                                tmp_mode = scan;
                        }
                }
        }

        if (temp_downclock < fixed_mode->clock)
                return drm_mode_duplicate(&dev_priv->drm, tmp_mode);
        else
                return NULL;
}

/* adjusted_mode has been preset to be the panel's fixed mode */
void
intel_pch_panel_fitting(struct intel_crtc *intel_crtc,
                        struct intel_crtc_state *pipe_config,
                        int fitting_mode)
{
        const struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
        int x = 0, y = 0, width = 0, height = 0;

        /* Native modes don't need fitting */
        if (adjusted_mode->crtc_hdisplay == pipe_config->pipe_src_w &&
            adjusted_mode->crtc_vdisplay == pipe_config->pipe_src_h &&
            pipe_config->output_format != INTEL_OUTPUT_FORMAT_YCBCR420)
                goto done;

        switch (fitting_mode) {
        case DRM_MODE_SCALE_CENTER:
                width = pipe_config->pipe_src_w;
                height = pipe_config->pipe_src_h;
                x = (adjusted_mode->crtc_hdisplay - width + 1)/2;
                y = (adjusted_mode->crtc_vdisplay - height + 1)/2;
                break;

        case DRM_MODE_SCALE_ASPECT:
                /* Scale but preserve the aspect ratio */
                {
                        u32 scaled_width = adjusted_mode->crtc_hdisplay
                                * pipe_config->pipe_src_h;
                        u32 scaled_height = pipe_config->pipe_src_w
                                * adjusted_mode->crtc_vdisplay;
                        if (scaled_width > scaled_height) { /* pillar */
                                width = scaled_height / pipe_config->pipe_src_h;
                                if (width & 1)
                                        width++;
                                x = (adjusted_mode->crtc_hdisplay - width + 1) / 2;
                                y = 0;
                                height = adjusted_mode->crtc_vdisplay;
                        } else if (scaled_width < scaled_height) { /* letter */
                                height = scaled_width / pipe_config->pipe_src_w;
                                if (height & 1)
                                    height++;
                                y = (adjusted_mode->crtc_vdisplay - height + 1) / 2;
                                x = 0;
                                width = adjusted_mode->crtc_hdisplay;
                        } else {
                                x = y = 0;
                                width = adjusted_mode->crtc_hdisplay;
                                height = adjusted_mode->crtc_vdisplay;
                        }
                }
                break;

        case DRM_MODE_SCALE_FULLSCREEN:
                x = y = 0;
                width = adjusted_mode->crtc_hdisplay;
                height = adjusted_mode->crtc_vdisplay;
                break;

        default:
                WARN(1, "bad panel fit mode: %d\n", fitting_mode);
                return;
        }

done:
        pipe_config->pch_pfit.pos = (x << 16) | y;
        pipe_config->pch_pfit.size = (width << 16) | height;
        pipe_config->pch_pfit.enabled = pipe_config->pch_pfit.size != 0;
}

static void
centre_horizontally(struct drm_display_mode *adjusted_mode,
                    int width)
{
        u32 border, sync_pos, blank_width, sync_width;

        /* keep the hsync and hblank widths constant */
        sync_width = adjusted_mode->crtc_hsync_end - adjusted_mode->crtc_hsync_start;
        blank_width = adjusted_mode->crtc_hblank_end - adjusted_mode->crtc_hblank_start;
        sync_pos = (blank_width - sync_width + 1) / 2;

        border = (adjusted_mode->crtc_hdisplay - width + 1) / 2;
        border += border & 1; /* make the border even */

        adjusted_mode->crtc_hdisplay = width;
        adjusted_mode->crtc_hblank_start = width + border;
        adjusted_mode->crtc_hblank_end = adjusted_mode->crtc_hblank_start + blank_width;

        adjusted_mode->crtc_hsync_start = adjusted_mode->crtc_hblank_start + sync_pos;
        adjusted_mode->crtc_hsync_end = adjusted_mode->crtc_hsync_start + sync_width;
}

static void
centre_vertically(struct drm_display_mode *adjusted_mode,
                  int height)
{
        u32 border, sync_pos, blank_width, sync_width;

        /* keep the vsync and vblank widths constant */
        sync_width = adjusted_mode->crtc_vsync_end - adjusted_mode->crtc_vsync_start;
        blank_width = adjusted_mode->crtc_vblank_end - adjusted_mode->crtc_vblank_start;
        sync_pos = (blank_width - sync_width + 1) / 2;

        border = (adjusted_mode->crtc_vdisplay - height + 1) / 2;

        adjusted_mode->crtc_vdisplay = height;
        adjusted_mode->crtc_vblank_start = height + border;
        adjusted_mode->crtc_vblank_end = adjusted_mode->crtc_vblank_start + blank_width;

        adjusted_mode->crtc_vsync_start = adjusted_mode->crtc_vblank_start + sync_pos;
        adjusted_mode->crtc_vsync_end = adjusted_mode->crtc_vsync_start + sync_width;
}

static inline u32 panel_fitter_scaling(u32 source, u32 target)
{
        /*
         * Floating point operation is not supported. So the FACTOR
         * is defined, which can avoid the floating point computation
         * when calculating the panel ratio.
         */
#define ACCURACY 12
#define FACTOR (1 << ACCURACY)
        u32 ratio = source * FACTOR / target;
        return (FACTOR * ratio + FACTOR/2) / FACTOR;
}

static void i965_scale_aspect(struct intel_crtc_state *pipe_config,
                              u32 *pfit_control)
{
        const struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
        u32 scaled_width = adjusted_mode->crtc_hdisplay *
                pipe_config->pipe_src_h;
        u32 scaled_height = pipe_config->pipe_src_w *
                adjusted_mode->crtc_vdisplay;

        /* 965+ is easy, it does everything in hw */
        if (scaled_width > scaled_height)
                *pfit_control |= PFIT_ENABLE |
                        PFIT_SCALING_PILLAR;
        else if (scaled_width < scaled_height)
                *pfit_control |= PFIT_ENABLE |
                        PFIT_SCALING_LETTER;
        else if (adjusted_mode->crtc_hdisplay != pipe_config->pipe_src_w)
                *pfit_control |= PFIT_ENABLE | PFIT_SCALING_AUTO;
}

static void i9xx_scale_aspect(struct intel_crtc_state *pipe_config,
                              u32 *pfit_control, u32 *pfit_pgm_ratios,
                              u32 *border)
{
        struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
        u32 scaled_width = adjusted_mode->crtc_hdisplay *
                pipe_config->pipe_src_h;
        u32 scaled_height = pipe_config->pipe_src_w *
                adjusted_mode->crtc_vdisplay;
        u32 bits;

        /*
         * For earlier chips we have to calculate the scaling
         * ratio by hand and program it into the
         * PFIT_PGM_RATIO register
         */
        if (scaled_width > scaled_height) { /* pillar */
                centre_horizontally(adjusted_mode,
                                    scaled_height /
                                    pipe_config->pipe_src_h);

                *border = LVDS_BORDER_ENABLE;
                if (pipe_config->pipe_src_h != adjusted_mode->crtc_vdisplay) {
                        bits = panel_fitter_scaling(pipe_config->pipe_src_h,
                                                    adjusted_mode->crtc_vdisplay);

                        *pfit_pgm_ratios |= (bits << PFIT_HORIZ_SCALE_SHIFT |
                                             bits << PFIT_VERT_SCALE_SHIFT);
                        *pfit_control |= (PFIT_ENABLE |
                                          VERT_INTERP_BILINEAR |
                                          HORIZ_INTERP_BILINEAR);
                }
        } else if (scaled_width < scaled_height) { /* letter */
                centre_vertically(adjusted_mode,
                                  scaled_width /
                                  pipe_config->pipe_src_w);

                *border = LVDS_BORDER_ENABLE;
                if (pipe_config->pipe_src_w != adjusted_mode->crtc_hdisplay) {
                        bits = panel_fitter_scaling(pipe_config->pipe_src_w,
                                                    adjusted_mode->crtc_hdisplay);

                        *pfit_pgm_ratios |= (bits << PFIT_HORIZ_SCALE_SHIFT |
                                             bits << PFIT_VERT_SCALE_SHIFT);
                        *pfit_control |= (PFIT_ENABLE |
                                          VERT_INTERP_BILINEAR |
                                          HORIZ_INTERP_BILINEAR);
                }
        } else {
                /* Aspects match, Let hw scale both directions */
                *pfit_control |= (PFIT_ENABLE |
                                  VERT_AUTO_SCALE | HORIZ_AUTO_SCALE |
                                  VERT_INTERP_BILINEAR |
                                  HORIZ_INTERP_BILINEAR);
        }
}

void intel_gmch_panel_fitting(struct intel_crtc *intel_crtc,
                              struct intel_crtc_state *pipe_config,
                              int fitting_mode)
{
        struct drm_i915_private *dev_priv = to_i915(intel_crtc->base.dev);
        u32 pfit_control = 0, pfit_pgm_ratios = 0, border = 0;
        struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;

        /* Native modes don't need fitting */
        if (adjusted_mode->crtc_hdisplay == pipe_config->pipe_src_w &&
            adjusted_mode->crtc_vdisplay == pipe_config->pipe_src_h)
                goto out;

        switch (fitting_mode) {
        case DRM_MODE_SCALE_CENTER:
                /*
                 * For centered modes, we have to calculate border widths &
                 * heights and modify the values programmed into the CRTC.
                 */
                centre_horizontally(adjusted_mode, pipe_config->pipe_src_w);
                centre_vertically(adjusted_mode, pipe_config->pipe_src_h);
                border = LVDS_BORDER_ENABLE;
                break;
        case DRM_MODE_SCALE_ASPECT:
                /* Scale but preserve the aspect ratio */
                if (INTEL_GEN(dev_priv) >= 4)
                        i965_scale_aspect(pipe_config, &pfit_control);
                else
                        i9xx_scale_aspect(pipe_config, &pfit_control,
                                          &pfit_pgm_ratios, &border);
                break;
        case DRM_MODE_SCALE_FULLSCREEN:
                /*
                 * Full scaling, even if it changes the aspect ratio.
                 * Fortunately this is all done for us in hw.
                 */
                if (pipe_config->pipe_src_h != adjusted_mode->crtc_vdisplay ||
                    pipe_config->pipe_src_w != adjusted_mode->crtc_hdisplay) {
                        pfit_control |= PFIT_ENABLE;
                        if (INTEL_GEN(dev_priv) >= 4)
                                pfit_control |= PFIT_SCALING_AUTO;
                        else
                                pfit_control |= (VERT_AUTO_SCALE |
                                                 VERT_INTERP_BILINEAR |
                                                 HORIZ_AUTO_SCALE |
                                                 HORIZ_INTERP_BILINEAR);
                }
                break;
        default:
                WARN(1, "bad panel fit mode: %d\n", fitting_mode);
                return;
        }

        /* 965+ wants fuzzy fitting */
        /* FIXME: handle multiple panels by failing gracefully */
        if (INTEL_GEN(dev_priv) >= 4)
                pfit_control |= ((intel_crtc->pipe << PFIT_PIPE_SHIFT) |
                                 PFIT_FILTER_FUZZY);

out:
        if ((pfit_control & PFIT_ENABLE) == 0) {
                pfit_control = 0;
                pfit_pgm_ratios = 0;
        }

        /* Make sure pre-965 set dither correctly for 18bpp panels. */
        if (INTEL_GEN(dev_priv) < 4 && pipe_config->pipe_bpp == 18)
                pfit_control |= PANEL_8TO6_DITHER_ENABLE;

        pipe_config->gmch_pfit.control = pfit_control;
        pipe_config->gmch_pfit.pgm_ratios = pfit_pgm_ratios;
        pipe_config->gmch_pfit.lvds_border_bits = border;
}

/**
 * scale - scale values from one range to another
 * @source_val: value in range [@source_min..@source_max]
 * @source_min: minimum legal value for @source_val
 * @source_max: maximum legal value for @source_val
 * @target_min: corresponding target value for @source_min
 * @target_max: corresponding target value for @source_max
 *
 * Return @source_val in range [@source_min..@source_max] scaled to range
 * [@target_min..@target_max].
 */
static u32 scale(u32 source_val,
                 u32 source_min, u32 source_max,
                 u32 target_min, u32 target_max)
{
        u64 target_val;

        WARN_ON(source_min > source_max);
        WARN_ON(target_min > target_max);

        /* defensive */
        source_val = clamp(source_val, source_min, source_max);

        /* avoid overflows */
        target_val = mul_u32_u32(source_val - source_min,
                                 target_max - target_min);
        target_val = DIV_ROUND_CLOSEST_ULL(target_val, source_max - source_min);
        target_val += target_min;

        return target_val;
}

/* Scale user_level in range [0..user_max] to [hw_min..hw_max]. */
static inline u32 scale_user_to_hw(struct intel_connector *connector,
                                   u32 user_level, u32 user_max)
{
        struct intel_panel *panel = &connector->panel;

        return scale(user_level, 0, user_max,
                     panel->backlight.min, panel->backlight.max);
}

/* Scale user_level in range [0..user_max] to [0..hw_max], clamping the result
 * to [hw_min..hw_max]. */
static inline u32 clamp_user_to_hw(struct intel_connector *connector,
                                   u32 user_level, u32 user_max)
{
        struct intel_panel *panel = &connector->panel;
        u32 hw_level;

        hw_level = scale(user_level, 0, user_max, 0, panel->backlight.max);
        hw_level = clamp(hw_level, panel->backlight.min, panel->backlight.max);

        return hw_level;
}

/* Scale hw_level in range [hw_min..hw_max] to [0..user_max]. */
static inline u32 scale_hw_to_user(struct intel_connector *connector,
                                   u32 hw_level, u32 user_max)
{
        struct intel_panel *panel = &connector->panel;

        return scale(hw_level, panel->backlight.min, panel->backlight.max,
                     0, user_max);
}

static u32 intel_panel_compute_brightness(struct intel_connector *connector,
                                          u32 val)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;

        WARN_ON(panel->backlight.max == 0);

        if (i915_modparams.invert_brightness < 0)
                return val;

        if (i915_modparams.invert_brightness > 0 ||
            dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS) {
                return panel->backlight.max - val + panel->backlight.min;
        }

        return val;
}

static u32 lpt_get_backlight(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);

        return I915_READ(BLC_PWM_PCH_CTL2) & BACKLIGHT_DUTY_CYCLE_MASK;
}

static u32 pch_get_backlight(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);

        return I915_READ(BLC_PWM_CPU_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
}

static u32 i9xx_get_backlight(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 val;

        val = I915_READ(BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
        if (INTEL_GEN(dev_priv) < 4)
                val >>= 1;

        if (panel->backlight.combination_mode) {
                u8 lbpc;

                pci_read_config_byte(dev_priv->drm.pdev, LBPC, &lbpc);
                val *= lbpc;
        }

        return val;
}

static u32 _vlv_get_backlight(struct drm_i915_private *dev_priv, enum pipe pipe)
{
        if (WARN_ON(pipe != PIPE_A && pipe != PIPE_B))
                return 0;

        return I915_READ(VLV_BLC_PWM_CTL(pipe)) & BACKLIGHT_DUTY_CYCLE_MASK;
}

static u32 vlv_get_backlight(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        enum pipe pipe = intel_connector_get_pipe(connector);

        return _vlv_get_backlight(dev_priv, pipe);
}

static u32 bxt_get_backlight(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;

        return I915_READ(BXT_BLC_PWM_DUTY(panel->backlight.controller));
}

static u32 pwm_get_backlight(struct intel_connector *connector)
{
        struct intel_panel *panel = &connector->panel;
        int duty_ns;

        duty_ns = pwm_get_duty_cycle(panel->backlight.pwm);
        return DIV_ROUND_UP(duty_ns * 100, CRC_PMIC_PWM_PERIOD_NS);
}

static void lpt_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);

        u32 val = I915_READ(BLC_PWM_PCH_CTL2) & ~BACKLIGHT_DUTY_CYCLE_MASK;
        I915_WRITE(BLC_PWM_PCH_CTL2, val | level);
}

static void pch_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        u32 tmp;

        tmp = I915_READ(BLC_PWM_CPU_CTL) & ~BACKLIGHT_DUTY_CYCLE_MASK;
        I915_WRITE(BLC_PWM_CPU_CTL, tmp | level);
}

static void i9xx_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 tmp, mask;

        WARN_ON(panel->backlight.max == 0);

        if (panel->backlight.combination_mode) {
                u8 lbpc;

                lbpc = level * 0xfe / panel->backlight.max + 1;
                level /= lbpc;
                pci_write_config_byte(dev_priv->drm.pdev, LBPC, lbpc);
        }

        if (IS_GEN(dev_priv, 4)) {
                mask = BACKLIGHT_DUTY_CYCLE_MASK;
        } else {
                level <<= 1;
                mask = BACKLIGHT_DUTY_CYCLE_MASK_PNV;
        }

        tmp = I915_READ(BLC_PWM_CTL) & ~mask;
        I915_WRITE(BLC_PWM_CTL, tmp | level);
}

static void vlv_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        enum pipe pipe = to_intel_crtc(conn_state->crtc)->pipe;
        u32 tmp;

        tmp = I915_READ(VLV_BLC_PWM_CTL(pipe)) & ~BACKLIGHT_DUTY_CYCLE_MASK;
        I915_WRITE(VLV_BLC_PWM_CTL(pipe), tmp | level);
}

static void bxt_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;

        I915_WRITE(BXT_BLC_PWM_DUTY(panel->backlight.controller), level);
}

static void pwm_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
        struct intel_panel *panel = &to_intel_connector(conn_state->connector)->panel;
        int duty_ns = DIV_ROUND_UP(level * CRC_PMIC_PWM_PERIOD_NS, 100);

        pwm_config(panel->backlight.pwm, duty_ns, CRC_PMIC_PWM_PERIOD_NS);
}

static void
intel_panel_actually_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct intel_panel *panel = &connector->panel;

        DRM_DEBUG_DRIVER("set backlight PWM = %d\n", level);

        level = intel_panel_compute_brightness(connector, level);
        panel->backlight.set(conn_state, level);
}

/* set backlight brightness to level in range [0..max], assuming hw min is
 * respected.
 */
void intel_panel_set_backlight_acpi(const struct drm_connector_state *conn_state,
                                    u32 user_level, u32 user_max)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 hw_level;

        /*
         * Lack of crtc may occur during driver init because
         * connection_mutex isn't held across the entire backlight
         * setup + modeset readout, and the BIOS can issue the
         * requests at any time.
         */
        if (!panel->backlight.present || !conn_state->crtc)
                return;

        mutex_lock(&dev_priv->backlight_lock);

        WARN_ON(panel->backlight.max == 0);

        hw_level = clamp_user_to_hw(connector, user_level, user_max);
        panel->backlight.level = hw_level;

        if (panel->backlight.device)
                panel->backlight.device->props.brightness =
                        scale_hw_to_user(connector,
                                         panel->backlight.level,
                                         panel->backlight.device->props.max_brightness);

        if (panel->backlight.enabled)
                intel_panel_actually_set_backlight(conn_state, hw_level);

        mutex_unlock(&dev_priv->backlight_lock);
}

static void lpt_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        u32 tmp;

        intel_panel_actually_set_backlight(old_conn_state, 0);

        /*
         * Although we don't support or enable CPU PWM with LPT/SPT based
         * systems, it may have been enabled prior to loading the
         * driver. Disable to avoid warnings on LCPLL disable.
         *
         * This needs rework if we need to add support for CPU PWM on PCH split
         * platforms.
         */
        tmp = I915_READ(BLC_PWM_CPU_CTL2);
        if (tmp & BLM_PWM_ENABLE) {
                DRM_DEBUG_KMS("cpu backlight was enabled, disabling\n");
                I915_WRITE(BLC_PWM_CPU_CTL2, tmp & ~BLM_PWM_ENABLE);
        }

        tmp = I915_READ(BLC_PWM_PCH_CTL1);
        I915_WRITE(BLC_PWM_PCH_CTL1, tmp & ~BLM_PCH_PWM_ENABLE);
}

static void pch_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        u32 tmp;

        intel_panel_actually_set_backlight(old_conn_state, 0);

        tmp = I915_READ(BLC_PWM_CPU_CTL2);
        I915_WRITE(BLC_PWM_CPU_CTL2, tmp & ~BLM_PWM_ENABLE);

        tmp = I915_READ(BLC_PWM_PCH_CTL1);
        I915_WRITE(BLC_PWM_PCH_CTL1, tmp & ~BLM_PCH_PWM_ENABLE);
}

static void i9xx_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        intel_panel_actually_set_backlight(old_conn_state, 0);
}

static void i965_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct drm_i915_private *dev_priv = to_i915(old_conn_state->connector->dev);
        u32 tmp;

        intel_panel_actually_set_backlight(old_conn_state, 0);

        tmp = I915_READ(BLC_PWM_CTL2);
        I915_WRITE(BLC_PWM_CTL2, tmp & ~BLM_PWM_ENABLE);
}

static void vlv_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        enum pipe pipe = to_intel_crtc(old_conn_state->crtc)->pipe;
        u32 tmp;

        intel_panel_actually_set_backlight(old_conn_state, 0);

        tmp = I915_READ(VLV_BLC_PWM_CTL2(pipe));
        I915_WRITE(VLV_BLC_PWM_CTL2(pipe), tmp & ~BLM_PWM_ENABLE);
}

static void bxt_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 tmp, val;

        intel_panel_actually_set_backlight(old_conn_state, 0);

        tmp = I915_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));
        I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller),
                        tmp & ~BXT_BLC_PWM_ENABLE);

        if (panel->backlight.controller == 1) {
                val = I915_READ(UTIL_PIN_CTL);
                val &= ~UTIL_PIN_ENABLE;
                I915_WRITE(UTIL_PIN_CTL, val);
        }
}

static void cnp_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 tmp;

        intel_panel_actually_set_backlight(old_conn_state, 0);

        tmp = I915_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));
        I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller),
                   tmp & ~BXT_BLC_PWM_ENABLE);
}

static void pwm_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
        struct intel_panel *panel = &connector->panel;

        /* Disable the backlight */
        intel_panel_actually_set_backlight(old_conn_state, 0);
        usleep_range(2000, 3000);
        pwm_disable(panel->backlight.pwm);
}

void intel_panel_disable_backlight(const struct drm_connector_state *old_conn_state)
{
        struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;

        if (!panel->backlight.present)
                return;

        /*
         * Do not disable backlight on the vga_switcheroo path. When switching
         * away from i915, the other client may depend on i915 to handle the
         * backlight. This will leave the backlight on unnecessarily when
         * another client is not activated.
         */
        if (dev_priv->drm.switch_power_state == DRM_SWITCH_POWER_CHANGING) {
                DRM_DEBUG_DRIVER("Skipping backlight disable on vga switch\n");
                return;
        }

        mutex_lock(&dev_priv->backlight_lock);

        if (panel->backlight.device)
                panel->backlight.device->props.power = FB_BLANK_POWERDOWN;
        panel->backlight.enabled = false;
        panel->backlight.disable(old_conn_state);

        mutex_unlock(&dev_priv->backlight_lock);
}

static void lpt_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 pch_ctl1, pch_ctl2, schicken;

        pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
        if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
                DRM_DEBUG_KMS("pch backlight already enabled\n");
                pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
                I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
        }

        if (HAS_PCH_LPT(dev_priv)) {
                schicken = I915_READ(SOUTH_CHICKEN2);
                if (panel->backlight.alternate_pwm_increment)
                        schicken |= LPT_PWM_GRANULARITY;
                else
                        schicken &= ~LPT_PWM_GRANULARITY;
                I915_WRITE(SOUTH_CHICKEN2, schicken);
        } else {
                schicken = I915_READ(SOUTH_CHICKEN1);
                if (panel->backlight.alternate_pwm_increment)
                        schicken |= SPT_PWM_GRANULARITY;
                else
                        schicken &= ~SPT_PWM_GRANULARITY;
                I915_WRITE(SOUTH_CHICKEN1, schicken);
        }

        pch_ctl2 = panel->backlight.max << 16;
        I915_WRITE(BLC_PWM_PCH_CTL2, pch_ctl2);

        pch_ctl1 = 0;
        if (panel->backlight.active_low_pwm)
                pch_ctl1 |= BLM_PCH_POLARITY;

        /* After LPT, override is the default. */
        if (HAS_PCH_LPT(dev_priv))
                pch_ctl1 |= BLM_PCH_OVERRIDE_ENABLE;

        I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
        POSTING_READ(BLC_PWM_PCH_CTL1);
        I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1 | BLM_PCH_PWM_ENABLE);

        /* This won't stick until the above enable. */
        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);
}

static void pch_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
        u32 cpu_ctl2, pch_ctl1, pch_ctl2;

        cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
        if (cpu_ctl2 & BLM_PWM_ENABLE) {
                DRM_DEBUG_KMS("cpu backlight already enabled\n");
                cpu_ctl2 &= ~BLM_PWM_ENABLE;
                I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2);
        }

        pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
        if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
                DRM_DEBUG_KMS("pch backlight already enabled\n");
                pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
                I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
        }

        if (cpu_transcoder == TRANSCODER_EDP)
                cpu_ctl2 = BLM_TRANSCODER_EDP;
        else
                cpu_ctl2 = BLM_PIPE(cpu_transcoder);
        I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2);
        POSTING_READ(BLC_PWM_CPU_CTL2);
        I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2 | BLM_PWM_ENABLE);

        /* This won't stick until the above enable. */
        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);

        pch_ctl2 = panel->backlight.max << 16;
        I915_WRITE(BLC_PWM_PCH_CTL2, pch_ctl2);

        pch_ctl1 = 0;
        if (panel->backlight.active_low_pwm)
                pch_ctl1 |= BLM_PCH_POLARITY;

        I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
        POSTING_READ(BLC_PWM_PCH_CTL1);
        I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1 | BLM_PCH_PWM_ENABLE);
}

static void i9xx_enable_backlight(const struct intel_crtc_state *crtc_state,
                                  const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 ctl, freq;

        ctl = I915_READ(BLC_PWM_CTL);
        if (ctl & BACKLIGHT_DUTY_CYCLE_MASK_PNV) {
                DRM_DEBUG_KMS("backlight already enabled\n");
                I915_WRITE(BLC_PWM_CTL, 0);
        }

        freq = panel->backlight.max;
        if (panel->backlight.combination_mode)
                freq /= 0xff;

        ctl = freq << 17;
        if (panel->backlight.combination_mode)
                ctl |= BLM_LEGACY_MODE;
        if (IS_PINEVIEW(dev_priv) && panel->backlight.active_low_pwm)
                ctl |= BLM_POLARITY_PNV;

        I915_WRITE(BLC_PWM_CTL, ctl);
        POSTING_READ(BLC_PWM_CTL);

        /* XXX: combine this into above write? */
        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);

        /*
         * Needed to enable backlight on some 855gm models. BLC_HIST_CTL is
         * 855gm only, but checking for gen2 is safe, as 855gm is the only gen2
         * that has backlight.
         */
        if (IS_GEN(dev_priv, 2))
                I915_WRITE(BLC_HIST_CTL, BLM_HISTOGRAM_ENABLE);
}

static void i965_enable_backlight(const struct intel_crtc_state *crtc_state,
                                  const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        enum pipe pipe = to_intel_crtc(conn_state->crtc)->pipe;
        u32 ctl, ctl2, freq;

        ctl2 = I915_READ(BLC_PWM_CTL2);
        if (ctl2 & BLM_PWM_ENABLE) {
                DRM_DEBUG_KMS("backlight already enabled\n");
                ctl2 &= ~BLM_PWM_ENABLE;
                I915_WRITE(BLC_PWM_CTL2, ctl2);
        }

        freq = panel->backlight.max;
        if (panel->backlight.combination_mode)
                freq /= 0xff;

        ctl = freq << 16;
        I915_WRITE(BLC_PWM_CTL, ctl);

        ctl2 = BLM_PIPE(pipe);
        if (panel->backlight.combination_mode)
                ctl2 |= BLM_COMBINATION_MODE;
        if (panel->backlight.active_low_pwm)
                ctl2 |= BLM_POLARITY_I965;
        I915_WRITE(BLC_PWM_CTL2, ctl2);
        POSTING_READ(BLC_PWM_CTL2);
        I915_WRITE(BLC_PWM_CTL2, ctl2 | BLM_PWM_ENABLE);

        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);
}

static void vlv_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        enum pipe pipe = to_intel_crtc(crtc_state->base.crtc)->pipe;
        u32 ctl, ctl2;

        ctl2 = I915_READ(VLV_BLC_PWM_CTL2(pipe));
        if (ctl2 & BLM_PWM_ENABLE) {
                DRM_DEBUG_KMS("backlight already enabled\n");
                ctl2 &= ~BLM_PWM_ENABLE;
                I915_WRITE(VLV_BLC_PWM_CTL2(pipe), ctl2);
        }

        ctl = panel->backlight.max << 16;
        I915_WRITE(VLV_BLC_PWM_CTL(pipe), ctl);

        /* XXX: combine this into above write? */
        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);

        ctl2 = 0;
        if (panel->backlight.active_low_pwm)
                ctl2 |= BLM_POLARITY_I965;
        I915_WRITE(VLV_BLC_PWM_CTL2(pipe), ctl2);
        POSTING_READ(VLV_BLC_PWM_CTL2(pipe));
        I915_WRITE(VLV_BLC_PWM_CTL2(pipe), ctl2 | BLM_PWM_ENABLE);
}

static void bxt_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        enum pipe pipe = to_intel_crtc(crtc_state->base.crtc)->pipe;
        u32 pwm_ctl, val;

        /* Controller 1 uses the utility pin. */
        if (panel->backlight.controller == 1) {
                val = I915_READ(UTIL_PIN_CTL);
                if (val & UTIL_PIN_ENABLE) {
                        DRM_DEBUG_KMS("util pin already enabled\n");
                        val &= ~UTIL_PIN_ENABLE;
                        I915_WRITE(UTIL_PIN_CTL, val);
                }

                val = 0;
                if (panel->backlight.util_pin_active_low)
                        val |= UTIL_PIN_POLARITY;
                I915_WRITE(UTIL_PIN_CTL, val | UTIL_PIN_PIPE(pipe) |
                                UTIL_PIN_MODE_PWM | UTIL_PIN_ENABLE);
        }

        pwm_ctl = I915_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));
        if (pwm_ctl & BXT_BLC_PWM_ENABLE) {
                DRM_DEBUG_KMS("backlight already enabled\n");
                pwm_ctl &= ~BXT_BLC_PWM_ENABLE;
                I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller),
                                pwm_ctl);
        }

        I915_WRITE(BXT_BLC_PWM_FREQ(panel->backlight.controller),
                        panel->backlight.max);

        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);

        pwm_ctl = 0;
        if (panel->backlight.active_low_pwm)
                pwm_ctl |= BXT_BLC_PWM_POLARITY;

        I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller), pwm_ctl);
        POSTING_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));
        I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller),
                        pwm_ctl | BXT_BLC_PWM_ENABLE);
}

static void cnp_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 pwm_ctl;

        pwm_ctl = I915_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));
        if (pwm_ctl & BXT_BLC_PWM_ENABLE) {
                DRM_DEBUG_KMS("backlight already enabled\n");
                pwm_ctl &= ~BXT_BLC_PWM_ENABLE;
                I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller),
                           pwm_ctl);
        }

        I915_WRITE(BXT_BLC_PWM_FREQ(panel->backlight.controller),
                   panel->backlight.max);

        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);

        pwm_ctl = 0;
        if (panel->backlight.active_low_pwm)
                pwm_ctl |= BXT_BLC_PWM_POLARITY;

        I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller), pwm_ctl);
        POSTING_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));
        I915_WRITE(BXT_BLC_PWM_CTL(panel->backlight.controller),
                   pwm_ctl | BXT_BLC_PWM_ENABLE);
}

static void pwm_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct intel_panel *panel = &connector->panel;

        pwm_enable(panel->backlight.pwm);
        intel_panel_actually_set_backlight(conn_state, panel->backlight.level);
}

static void __intel_panel_enable_backlight(const struct intel_crtc_state *crtc_state,
                                           const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct intel_panel *panel = &connector->panel;

        WARN_ON(panel->backlight.max == 0);

        if (panel->backlight.level <= panel->backlight.min) {
                panel->backlight.level = panel->backlight.max;
                if (panel->backlight.device)
                        panel->backlight.device->props.brightness =
                                scale_hw_to_user(connector,
                                                 panel->backlight.level,
                                                 panel->backlight.device->props.max_brightness);
        }

        panel->backlight.enable(crtc_state, conn_state);
        panel->backlight.enabled = true;
        if (panel->backlight.device)
                panel->backlight.device->props.power = FB_BLANK_UNBLANK;
}

void intel_panel_enable_backlight(const struct intel_crtc_state *crtc_state,
                                  const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        enum pipe pipe = to_intel_crtc(crtc_state->base.crtc)->pipe;

        if (!panel->backlight.present)
                return;

        DRM_DEBUG_KMS("pipe %c\n", pipe_name(pipe));

        mutex_lock(&dev_priv->backlight_lock);

        __intel_panel_enable_backlight(crtc_state, conn_state);

        mutex_unlock(&dev_priv->backlight_lock);
}

#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
static u32 intel_panel_get_backlight(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 val = 0;

        mutex_lock(&dev_priv->backlight_lock);

        if (panel->backlight.enabled) {
                val = panel->backlight.get(connector);
                val = intel_panel_compute_brightness(connector, val);
        }

        mutex_unlock(&dev_priv->backlight_lock);

        DRM_DEBUG_DRIVER("get backlight PWM = %d\n", val);
        return val;
}

/* set backlight brightness to level in range [0..max], scaling wrt hw min */
static void intel_panel_set_backlight(const struct drm_connector_state *conn_state,
                                      u32 user_level, u32 user_max)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 hw_level;

        if (!panel->backlight.present)
                return;

        mutex_lock(&dev_priv->backlight_lock);

        WARN_ON(panel->backlight.max == 0);

        hw_level = scale_user_to_hw(connector, user_level, user_max);
        panel->backlight.level = hw_level;

        if (panel->backlight.enabled)
                intel_panel_actually_set_backlight(conn_state, hw_level);

        mutex_unlock(&dev_priv->backlight_lock);
}

static int intel_backlight_device_update_status(struct backlight_device *bd)
{
        struct intel_connector *connector = bl_get_data(bd);
        struct intel_panel *panel = &connector->panel;
        struct drm_device *dev = connector->base.dev;

        drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
        DRM_DEBUG_KMS("updating intel_backlight, brightness=%d/%d\n",
                      bd->props.brightness, bd->props.max_brightness);
        intel_panel_set_backlight(connector->base.state, bd->props.brightness,
                                  bd->props.max_brightness);

        /*
         * Allow flipping bl_power as a sub-state of enabled. Sadly the
         * backlight class device does not make it easy to to differentiate
         * between callbacks for brightness and bl_power, so our backlight_power
         * callback needs to take this into account.
         */
        if (panel->backlight.enabled) {
                if (panel->backlight.power) {
                        bool enable = bd->props.power == FB_BLANK_UNBLANK &&
                                bd->props.brightness != 0;
                        panel->backlight.power(connector, enable);
                }
        } else {
                bd->props.power = FB_BLANK_POWERDOWN;
        }

        drm_modeset_unlock(&dev->mode_config.connection_mutex);
        return 0;
}

static int intel_backlight_device_get_brightness(struct backlight_device *bd)
{
        struct intel_connector *connector = bl_get_data(bd);
        struct drm_device *dev = connector->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        intel_wakeref_t wakeref;
        int ret = 0;

        with_intel_runtime_pm(dev_priv, wakeref) {
                u32 hw_level;

                drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);

                hw_level = intel_panel_get_backlight(connector);
                ret = scale_hw_to_user(connector,
                                       hw_level, bd->props.max_brightness);

                drm_modeset_unlock(&dev->mode_config.connection_mutex);
        }

        return ret;
}

static const struct backlight_ops intel_backlight_device_ops = {
        .update_status = intel_backlight_device_update_status,
        .get_brightness = intel_backlight_device_get_brightness,
};

int intel_backlight_device_register(struct intel_connector *connector)
{
        struct intel_panel *panel = &connector->panel;
        struct backlight_properties props;

        if (WARN_ON(panel->backlight.device))
                return -ENODEV;

        if (!panel->backlight.present)
                return 0;

        WARN_ON(panel->backlight.max == 0);

        memset(&props, 0, sizeof(props));
        props.type = BACKLIGHT_RAW;

        /*
         * Note: Everything should work even if the backlight device max
         * presented to the userspace is arbitrarily chosen.
         */
        props.max_brightness = panel->backlight.max;
        props.brightness = scale_hw_to_user(connector,
                                            panel->backlight.level,
                                            props.max_brightness);

        if (panel->backlight.enabled)
                props.power = FB_BLANK_UNBLANK;
        else
                props.power = FB_BLANK_POWERDOWN;

        /*
         * Note: using the same name independent of the connector prevents
         * registration of multiple backlight devices in the driver.
         */
        panel->backlight.device =
                backlight_device_register("intel_backlight",
                                          connector->base.kdev,
                                          connector,
                                          &intel_backlight_device_ops, &props);

        if (IS_ERR(panel->backlight.device)) {
                DRM_ERROR("Failed to register backlight: %ld\n",
                          PTR_ERR(panel->backlight.device));
                panel->backlight.device = NULL;
                return -ENODEV;
        }

        DRM_DEBUG_KMS("Connector %s backlight sysfs interface registered\n",
                      connector->base.name);

        return 0;
}

void intel_backlight_device_unregister(struct intel_connector *connector)
{
        struct intel_panel *panel = &connector->panel;

        if (panel->backlight.device) {
                backlight_device_unregister(panel->backlight.device);
                panel->backlight.device = NULL;
        }
}
#endif /* CONFIG_BACKLIGHT_CLASS_DEVICE */

/*
 * CNP: PWM clock frequency is 19.2 MHz or 24 MHz.
 *      PWM increment = 1
 */
static u32 cnp_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);

        return DIV_ROUND_CLOSEST(KHz(dev_priv->rawclk_freq), pwm_freq_hz);
}

/*
 * BXT: PWM clock frequency = 19.2 MHz.
 */
static u32 bxt_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        return DIV_ROUND_CLOSEST(KHz(19200), pwm_freq_hz);
}

/*
 * SPT: This value represents the period of the PWM stream in clock periods
 * multiplied by 16 (default increment) or 128 (alternate increment selected in
 * SCHICKEN_1 bit 0). PWM clock is 24 MHz.
 */
static u32 spt_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        struct intel_panel *panel = &connector->panel;
        u32 mul;

        if (panel->backlight.alternate_pwm_increment)
                mul = 128;
        else
                mul = 16;

        return DIV_ROUND_CLOSEST(MHz(24), pwm_freq_hz * mul);
}

/*
 * LPT: This value represents the period of the PWM stream in clock periods
 * multiplied by 128 (default increment) or 16 (alternate increment, selected in
 * LPT SOUTH_CHICKEN2 register bit 5).
 */
static u32 lpt_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 mul, clock;

        if (panel->backlight.alternate_pwm_increment)
                mul = 16;
        else
                mul = 128;

        if (HAS_PCH_LPT_H(dev_priv))
                clock = MHz(135); /* LPT:H */
        else
                clock = MHz(24); /* LPT:LP */

        return DIV_ROUND_CLOSEST(clock, pwm_freq_hz * mul);
}

/*
 * ILK/SNB/IVB: This value represents the period of the PWM stream in PCH
 * display raw clocks multiplied by 128.
 */
static u32 pch_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);

        return DIV_ROUND_CLOSEST(KHz(dev_priv->rawclk_freq), pwm_freq_hz * 128);
}

/*
 * Gen2: This field determines the number of time base events (display core
 * clock frequency/32) in total for a complete cycle of modulated backlight
 * control.
 *
 * Gen3: A time base event equals the display core clock ([DevPNV] HRAW clock)
 * divided by 32.
 */
static u32 i9xx_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        int clock;

        if (IS_PINEVIEW(dev_priv))
                clock = KHz(dev_priv->rawclk_freq);
        else
                clock = KHz(dev_priv->cdclk.hw.cdclk);

        return DIV_ROUND_CLOSEST(clock, pwm_freq_hz * 32);
}

/*
 * Gen4: This value represents the period of the PWM stream in display core
 * clocks ([DevCTG] HRAW clocks) multiplied by 128.
 *
 */
static u32 i965_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        int clock;

        if (IS_G4X(dev_priv))
                clock = KHz(dev_priv->rawclk_freq);
        else
                clock = KHz(dev_priv->cdclk.hw.cdclk);

        return DIV_ROUND_CLOSEST(clock, pwm_freq_hz * 128);
}

/*
 * VLV: This value represents the period of the PWM stream in display core
 * clocks ([DevCTG] 200MHz HRAW clocks) multiplied by 128 or 25MHz S0IX clocks
 * multiplied by 16. CHV uses a 19.2MHz S0IX clock.
 */
static u32 vlv_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        int mul, clock;

        if ((I915_READ(CBR1_VLV) & CBR_PWM_CLOCK_MUX_SELECT) == 0) {
                if (IS_CHERRYVIEW(dev_priv))
                        clock = KHz(19200);
                else
                        clock = MHz(25);
                mul = 16;
        } else {
                clock = KHz(dev_priv->rawclk_freq);
                mul = 128;
        }

        return DIV_ROUND_CLOSEST(clock, pwm_freq_hz * mul);
}

static u32 get_backlight_max_vbt(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u16 pwm_freq_hz = dev_priv->vbt.backlight.pwm_freq_hz;
        u32 pwm;

        if (!panel->backlight.hz_to_pwm) {
                DRM_DEBUG_KMS("backlight frequency conversion not supported\n");
                return 0;
        }

        if (pwm_freq_hz) {
                DRM_DEBUG_KMS("VBT defined backlight frequency %u Hz\n",
                              pwm_freq_hz);
        } else {
                pwm_freq_hz = 200;
                DRM_DEBUG_KMS("default backlight frequency %u Hz\n",
                              pwm_freq_hz);
        }

        pwm = panel->backlight.hz_to_pwm(connector, pwm_freq_hz);
        if (!pwm) {
                DRM_DEBUG_KMS("backlight frequency conversion failed\n");
                return 0;
        }

        return pwm;
}

/*
 * Note: The setup hooks can't assume pipe is set!
 */
static u32 get_backlight_min_vbt(struct intel_connector *connector)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        int min;

        WARN_ON(panel->backlight.max == 0);

        /*
         * XXX: If the vbt value is 255, it makes min equal to max, which leads
         * to problems. There are such machines out there. Either our
         * interpretation is wrong or the vbt has bogus data. Or both. Safeguard
         * against this by letting the minimum be at most (arbitrarily chosen)
         * 25% of the max.
         */
        min = clamp_t(int, dev_priv->vbt.backlight.min_brightness, 0, 64);
        if (min != dev_priv->vbt.backlight.min_brightness) {
                DRM_DEBUG_KMS("clamping VBT min backlight %d/255 to %d/255\n",
                              dev_priv->vbt.backlight.min_brightness, min);
        }

        /* vbt value is a coefficient in range [0..255] */
        return scale(min, 0, 255, 0, panel->backlight.max);
}

static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 cpu_ctl2, pch_ctl1, pch_ctl2, val;
        bool alt, cpu_mode;

        if (HAS_PCH_LPT(dev_priv))
                alt = I915_READ(SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY;
        else
                alt = I915_READ(SOUTH_CHICKEN1) & SPT_PWM_GRANULARITY;
        panel->backlight.alternate_pwm_increment = alt;

        pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
        panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;

        pch_ctl2 = I915_READ(BLC_PWM_PCH_CTL2);
        panel->backlight.max = pch_ctl2 >> 16;

        cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);

        if (!panel->backlight.max)
                panel->backlight.max = get_backlight_max_vbt(connector);

        if (!panel->backlight.max)
                return -ENODEV;

        panel->backlight.min = get_backlight_min_vbt(connector);

        panel->backlight.enabled = pch_ctl1 & BLM_PCH_PWM_ENABLE;

        cpu_mode = panel->backlight.enabled && HAS_PCH_LPT(dev_priv) &&
                   !(pch_ctl1 & BLM_PCH_OVERRIDE_ENABLE) &&
                   (cpu_ctl2 & BLM_PWM_ENABLE);
        if (cpu_mode)
                val = pch_get_backlight(connector);
        else
                val = lpt_get_backlight(connector);
        val = intel_panel_compute_brightness(connector, val);
        panel->backlight.level = clamp(val, panel->backlight.min,
                                       panel->backlight.max);

        if (cpu_mode) {
                DRM_DEBUG_KMS("CPU backlight register was enabled, switching to PCH override\n");

                /* Write converted CPU PWM value to PCH override register */
                lpt_set_backlight(connector->base.state, panel->backlight.level);
                I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1 | BLM_PCH_OVERRIDE_ENABLE);

                I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2 & ~BLM_PWM_ENABLE);
        }

        return 0;
}

static int pch_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 cpu_ctl2, pch_ctl1, pch_ctl2, val;

        pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
        panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;

        pch_ctl2 = I915_READ(BLC_PWM_PCH_CTL2);
        panel->backlight.max = pch_ctl2 >> 16;

        if (!panel->backlight.max)
                panel->backlight.max = get_backlight_max_vbt(connector);

        if (!panel->backlight.max)
                return -ENODEV;

        panel->backlight.min = get_backlight_min_vbt(connector);

        val = pch_get_backlight(connector);
        val = intel_panel_compute_brightness(connector, val);
        panel->backlight.level = clamp(val, panel->backlight.min,
                                       panel->backlight.max);

        cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
        panel->backlight.enabled = (cpu_ctl2 & BLM_PWM_ENABLE) &&
                (pch_ctl1 & BLM_PCH_PWM_ENABLE);

        return 0;
}

static int i9xx_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 ctl, val;

        ctl = I915_READ(BLC_PWM_CTL);

        if (IS_GEN(dev_priv, 2) || IS_I915GM(dev_priv) || IS_I945GM(dev_priv))
                panel->backlight.combination_mode = ctl & BLM_LEGACY_MODE;

        if (IS_PINEVIEW(dev_priv))
                panel->backlight.active_low_pwm = ctl & BLM_POLARITY_PNV;

        panel->backlight.max = ctl >> 17;

        if (!panel->backlight.max) {
                panel->backlight.max = get_backlight_max_vbt(connector);
                panel->backlight.max >>= 1;
        }

        if (!panel->backlight.max)
                return -ENODEV;

        if (panel->backlight.combination_mode)
                panel->backlight.max *= 0xff;

        panel->backlight.min = get_backlight_min_vbt(connector);

        val = i9xx_get_backlight(connector);
        val = intel_panel_compute_brightness(connector, val);
        panel->backlight.level = clamp(val, panel->backlight.min,
                                       panel->backlight.max);

        panel->backlight.enabled = val != 0;

        return 0;
}

static int i965_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 ctl, ctl2, val;

        ctl2 = I915_READ(BLC_PWM_CTL2);
        panel->backlight.combination_mode = ctl2 & BLM_COMBINATION_MODE;
        panel->backlight.active_low_pwm = ctl2 & BLM_POLARITY_I965;

        ctl = I915_READ(BLC_PWM_CTL);
        panel->backlight.max = ctl >> 16;

        if (!panel->backlight.max)
                panel->backlight.max = get_backlight_max_vbt(connector);

        if (!panel->backlight.max)
                return -ENODEV;

        if (panel->backlight.combination_mode)
                panel->backlight.max *= 0xff;

        panel->backlight.min = get_backlight_min_vbt(connector);

        val = i9xx_get_backlight(connector);
        val = intel_panel_compute_brightness(connector, val);
        panel->backlight.level = clamp(val, panel->backlight.min,
                                       panel->backlight.max);

        panel->backlight.enabled = ctl2 & BLM_PWM_ENABLE;

        return 0;
}

static int vlv_setup_backlight(struct intel_connector *connector, enum pipe pipe)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 ctl, ctl2, val;

        if (WARN_ON(pipe != PIPE_A && pipe != PIPE_B))
                return -ENODEV;

        ctl2 = I915_READ(VLV_BLC_PWM_CTL2(pipe));
        panel->backlight.active_low_pwm = ctl2 & BLM_POLARITY_I965;

        ctl = I915_READ(VLV_BLC_PWM_CTL(pipe));
        panel->backlight.max = ctl >> 16;

        if (!panel->backlight.max)
                panel->backlight.max = get_backlight_max_vbt(connector);

        if (!panel->backlight.max)
                return -ENODEV;

        panel->backlight.min = get_backlight_min_vbt(connector);

        val = _vlv_get_backlight(dev_priv, pipe);
        val = intel_panel_compute_brightness(connector, val);
        panel->backlight.level = clamp(val, panel->backlight.min,
                                       panel->backlight.max);

        panel->backlight.enabled = ctl2 & BLM_PWM_ENABLE;

        return 0;
}

static int
bxt_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 pwm_ctl, val;

        panel->backlight.controller = dev_priv->vbt.backlight.controller;

        pwm_ctl = I915_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));

        /* Controller 1 uses the utility pin. */
        if (panel->backlight.controller == 1) {
                val = I915_READ(UTIL_PIN_CTL);
                panel->backlight.util_pin_active_low =
                                        val & UTIL_PIN_POLARITY;
        }

        panel->backlight.active_low_pwm = pwm_ctl & BXT_BLC_PWM_POLARITY;
        panel->backlight.max =
                I915_READ(BXT_BLC_PWM_FREQ(panel->backlight.controller));

        if (!panel->backlight.max)
                panel->backlight.max = get_backlight_max_vbt(connector);

        if (!panel->backlight.max)
                return -ENODEV;

        panel->backlight.min = get_backlight_min_vbt(connector);

        val = bxt_get_backlight(connector);
        val = intel_panel_compute_brightness(connector, val);
        panel->backlight.level = clamp(val, panel->backlight.min,
                                       panel->backlight.max);

        panel->backlight.enabled = pwm_ctl & BXT_BLC_PWM_ENABLE;

        return 0;
}

static int
cnp_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        u32 pwm_ctl, val;

        /*
         * CNP has the BXT implementation of backlight, but with only one
         * controller. TODO: ICP has multiple controllers but we only use
         * controller 0 for now.
         */
        panel->backlight.controller = 0;

        pwm_ctl = I915_READ(BXT_BLC_PWM_CTL(panel->backlight.controller));

        panel->backlight.active_low_pwm = pwm_ctl & BXT_BLC_PWM_POLARITY;
        panel->backlight.max =
                I915_READ(BXT_BLC_PWM_FREQ(panel->backlight.controller));

        if (!panel->backlight.max)
                panel->backlight.max = get_backlight_max_vbt(connector);

        if (!panel->backlight.max)
                return -ENODEV;

        panel->backlight.min = get_backlight_min_vbt(connector);

        val = bxt_get_backlight(connector);
        val = intel_panel_compute_brightness(connector, val);
        panel->backlight.level = clamp(val, panel->backlight.min,
                                       panel->backlight.max);

        panel->backlight.enabled = pwm_ctl & BXT_BLC_PWM_ENABLE;

        return 0;
}

static int pwm_setup_backlight(struct intel_connector *connector,
                               enum pipe pipe)
{
        struct drm_device *dev = connector->base.dev;
        struct intel_panel *panel = &connector->panel;
        int retval;

        /* Get the PWM chip for backlight control */
        panel->backlight.pwm = pwm_get(dev->dev, "pwm_backlight");
        if (IS_ERR(panel->backlight.pwm)) {
                DRM_ERROR("Failed to own the pwm chip\n");
                panel->backlight.pwm = NULL;
                return -ENODEV;
        }

        /*
         * FIXME: pwm_apply_args() should be removed when switching to
         * the atomic PWM API.
         */
        pwm_apply_args(panel->backlight.pwm);

        retval = pwm_config(panel->backlight.pwm, CRC_PMIC_PWM_PERIOD_NS,
                            CRC_PMIC_PWM_PERIOD_NS);
        if (retval < 0) {
                DRM_ERROR("Failed to configure the pwm chip\n");
                pwm_put(panel->backlight.pwm);
                panel->backlight.pwm = NULL;
                return retval;
        }

        panel->backlight.min = 0; /* 0% */
        panel->backlight.max = 100; /* 100% */
        panel->backlight.level = DIV_ROUND_UP(
                                 pwm_get_duty_cycle(panel->backlight.pwm) * 100,
                                 CRC_PMIC_PWM_PERIOD_NS);
        panel->backlight.enabled = panel->backlight.level != 0;

        return 0;
}

void intel_panel_update_backlight(struct intel_encoder *encoder,
                                  const struct intel_crtc_state *crtc_state,
                                  const struct drm_connector_state *conn_state)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;

        if (!panel->backlight.present)
                return;

        mutex_lock(&dev_priv->backlight_lock);
        if (!panel->backlight.enabled)
                __intel_panel_enable_backlight(crtc_state, conn_state);

        mutex_unlock(&dev_priv->backlight_lock);
}

int intel_panel_setup_backlight(struct drm_connector *connector, enum pipe pipe)
{
        struct drm_i915_private *dev_priv = to_i915(connector->dev);
        struct intel_connector *intel_connector = to_intel_connector(connector);
        struct intel_panel *panel = &intel_connector->panel;
        int ret;

        if (!dev_priv->vbt.backlight.present) {
                if (dev_priv->quirks & QUIRK_BACKLIGHT_PRESENT) {
                        DRM_DEBUG_KMS("no backlight present per VBT, but present per quirk\n");
                } else {
                        DRM_DEBUG_KMS("no backlight present per VBT\n");
                        return 0;
                }
        }

        /* ensure intel_panel has been initialized first */
        if (WARN_ON(!panel->backlight.setup))
                return -ENODEV;

        /* set level and max in panel struct */
        mutex_lock(&dev_priv->backlight_lock);
        ret = panel->backlight.setup(intel_connector, pipe);
        mutex_unlock(&dev_priv->backlight_lock);

        if (ret) {
                DRM_DEBUG_KMS("failed to setup backlight for connector %s\n",
                              connector->name);
                return ret;
        }

        panel->backlight.present = true;

        DRM_DEBUG_KMS("Connector %s backlight initialized, %s, brightness %u/%u\n",
                      connector->name,
                      enableddisabled(panel->backlight.enabled),
                      panel->backlight.level, panel->backlight.max);

        return 0;
}

static void intel_panel_destroy_backlight(struct intel_panel *panel)
{
        /* dispose of the pwm */
        if (panel->backlight.pwm)
                pwm_put(panel->backlight.pwm);

        panel->backlight.present = false;
}

/* Set up chip specific backlight functions */
static void
intel_panel_init_backlight_funcs(struct intel_panel *panel)
{
        struct intel_connector *connector =
                container_of(panel, struct intel_connector, panel);
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);

        if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
            intel_dp_aux_init_backlight_funcs(connector) == 0)
                return;

        if (connector->base.connector_type == DRM_MODE_CONNECTOR_DSI &&
            intel_dsi_dcs_init_backlight_funcs(connector) == 0)
                return;

        if (IS_GEN9_LP(dev_priv)) {
                panel->backlight.setup = bxt_setup_backlight;
                panel->backlight.enable = bxt_enable_backlight;
                panel->backlight.disable = bxt_disable_backlight;
                panel->backlight.set = bxt_set_backlight;
                panel->backlight.get = bxt_get_backlight;
                panel->backlight.hz_to_pwm = bxt_hz_to_pwm;
        } else if (HAS_PCH_CNP(dev_priv) || HAS_PCH_ICP(dev_priv)) {
                panel->backlight.setup = cnp_setup_backlight;
                panel->backlight.enable = cnp_enable_backlight;
                panel->backlight.disable = cnp_disable_backlight;
                panel->backlight.set = bxt_set_backlight;
                panel->backlight.get = bxt_get_backlight;
                panel->backlight.hz_to_pwm = cnp_hz_to_pwm;
        } else if (HAS_PCH_LPT(dev_priv) || HAS_PCH_SPT(dev_priv) ||
                   HAS_PCH_KBP(dev_priv)) {
                panel->backlight.setup = lpt_setup_backlight;
                panel->backlight.enable = lpt_enable_backlight;
                panel->backlight.disable = lpt_disable_backlight;
                panel->backlight.set = lpt_set_backlight;
                panel->backlight.get = lpt_get_backlight;
                if (HAS_PCH_LPT(dev_priv))
                        panel->backlight.hz_to_pwm = lpt_hz_to_pwm;
                else
                        panel->backlight.hz_to_pwm = spt_hz_to_pwm;
        } else if (HAS_PCH_SPLIT(dev_priv)) {
                panel->backlight.setup = pch_setup_backlight;
                panel->backlight.enable = pch_enable_backlight;
                panel->backlight.disable = pch_disable_backlight;
                panel->backlight.set = pch_set_backlight;
                panel->backlight.get = pch_get_backlight;
                panel->backlight.hz_to_pwm = pch_hz_to_pwm;
        } else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
                if (connector->base.connector_type == DRM_MODE_CONNECTOR_DSI) {
                        panel->backlight.setup = pwm_setup_backlight;
                        panel->backlight.enable = pwm_enable_backlight;
                        panel->backlight.disable = pwm_disable_backlight;
                        panel->backlight.set = pwm_set_backlight;
                        panel->backlight.get = pwm_get_backlight;
                } else {
                        panel->backlight.setup = vlv_setup_backlight;
                        panel->backlight.enable = vlv_enable_backlight;
                        panel->backlight.disable = vlv_disable_backlight;
                        panel->backlight.set = vlv_set_backlight;
                        panel->backlight.get = vlv_get_backlight;
                        panel->backlight.hz_to_pwm = vlv_hz_to_pwm;
                }
        } else if (IS_GEN(dev_priv, 4)) {
                panel->backlight.setup = i965_setup_backlight;
                panel->backlight.enable = i965_enable_backlight;
                panel->backlight.disable = i965_disable_backlight;
                panel->backlight.set = i9xx_set_backlight;
                panel->backlight.get = i9xx_get_backlight;
                panel->backlight.hz_to_pwm = i965_hz_to_pwm;
        } else {
                panel->backlight.setup = i9xx_setup_backlight;
                panel->backlight.enable = i9xx_enable_backlight;
                panel->backlight.disable = i9xx_disable_backlight;
                panel->backlight.set = i9xx_set_backlight;
                panel->backlight.get = i9xx_get_backlight;
                panel->backlight.hz_to_pwm = i9xx_hz_to_pwm;
        }
}

int intel_panel_init(struct intel_panel *panel,
                     struct drm_display_mode *fixed_mode,
                     struct drm_display_mode *downclock_mode)
{
        intel_panel_init_backlight_funcs(panel);

        panel->fixed_mode = fixed_mode;
        panel->downclock_mode = downclock_mode;

        return 0;
}

void intel_panel_fini(struct intel_panel *panel)
{
        struct intel_connector *intel_connector =
                container_of(panel, struct intel_connector, panel);

        intel_panel_destroy_backlight(panel);

        if (panel->fixed_mode)
                drm_mode_destroy(intel_connector->base.dev, panel->fixed_mode);

        if (panel->downclock_mode)
                drm_mode_destroy(intel_connector->base.dev,
                                panel->downclock_mode);
}