// SPDX-License-Identifier: MIT
/*
 * Copyright © 2021 Intel Corporation
 */

#include <linux/kernel.h>
#include <linux/pwm.h>
#include <linux/string_helpers.h>

#include "intel_backlight.h"
#include "intel_connector.h"
#include "intel_de.h"
#include "intel_display_types.h"
#include "intel_dp_aux_backlight.h"
#include "intel_dsi_dcs_backlight.h"
#include "intel_panel.h"
#include "intel_pci_config.h"

/**
 * 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 [0..hw_max], clamping the result
 * to [hw_min..hw_max].
 */
static 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 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);
}

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

        drm_WARN_ON(&dev_priv->drm, panel->backlight.pwm_level_max == 0);

        if (dev_priv->params.invert_brightness < 0)
                return val;

        if (dev_priv->params.invert_brightness > 0 ||
            dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS) {
                return panel->backlight.pwm_level_max - val + panel->backlight.pwm_level_min;
        }

        return val;
}

void intel_backlight_set_pwm_level(const struct drm_connector_state *conn_state, u32 val)
{
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct drm_i915_private *i915 = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;

        drm_dbg_kms(&i915->drm, "set backlight PWM = %d\n", val);
        panel->backlight.pwm_funcs->set(conn_state, val);
}

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

        drm_WARN_ON_ONCE(&dev_priv->drm,
                         panel->backlight.max == 0 || panel->backlight.pwm_level_max == 0);

        val = scale(val, panel->backlight.min, panel->backlight.max,
                    panel->backlight.pwm_level_min, panel->backlight.pwm_level_max);

        return intel_backlight_invert_pwm_level(connector, val);
}

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

        drm_WARN_ON_ONCE(&dev_priv->drm,
                         panel->backlight.max == 0 || panel->backlight.pwm_level_max == 0);

        if (dev_priv->params.invert_brightness > 0 ||
            (dev_priv->params.invert_brightness == 0 && dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS))
                val = panel->backlight.pwm_level_max - (val - panel->backlight.pwm_level_min);

        return scale(val, panel->backlight.pwm_level_min, panel->backlight.pwm_level_max,
                     panel->backlight.min, panel->backlight.max);
}

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

        return intel_de_read(dev_priv, BLC_PWM_PCH_CTL2) & BACKLIGHT_DUTY_CYCLE_MASK;
}

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

        return intel_de_read(dev_priv, BLC_PWM_CPU_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
}

static u32 i9xx_get_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 val;

        val = intel_de_read(dev_priv, BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
        if (DISPLAY_VER(dev_priv) < 4)
                val >>= 1;

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

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

        return val;
}

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

        if (drm_WARN_ON(&dev_priv->drm, pipe != PIPE_A && pipe != PIPE_B))
                return 0;

        return intel_de_read(dev_priv, VLV_BLC_PWM_CTL(pipe)) & BACKLIGHT_DUTY_CYCLE_MASK;
}

static u32 bxt_get_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;

        return intel_de_read(dev_priv,
                             BXT_BLC_PWM_DUTY(panel->backlight.controller));
}

static u32 ext_pwm_get_backlight(struct intel_connector *connector, enum pipe unused)
{
        struct intel_panel *panel = &connector->panel;
        struct pwm_state state;

        pwm_get_state(panel->backlight.pwm, &state);
        return pwm_get_relative_duty_cycle(&state, 100);
}

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 = intel_de_read(dev_priv, BLC_PWM_PCH_CTL2) & ~BACKLIGHT_DUTY_CYCLE_MASK;
        intel_de_write(dev_priv, 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 = intel_de_read(dev_priv, BLC_PWM_CPU_CTL) & ~BACKLIGHT_DUTY_CYCLE_MASK;
        intel_de_write(dev_priv, 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;

        drm_WARN_ON(&dev_priv->drm, panel->backlight.pwm_level_max == 0);

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

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

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

        tmp = intel_de_read(dev_priv, BLC_PWM_CTL) & ~mask;
        intel_de_write(dev_priv, 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 = intel_de_read(dev_priv, VLV_BLC_PWM_CTL(pipe)) & ~BACKLIGHT_DUTY_CYCLE_MASK;
        intel_de_write(dev_priv, 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;

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

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

        pwm_set_relative_duty_cycle(&panel->backlight.pwm_state, level, 100);
        pwm_apply_state(panel->backlight.pwm, &panel->backlight.pwm_state);
}

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 drm_i915_private *i915 = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;

        drm_dbg_kms(&i915->drm, "set backlight level = %d\n", level);

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

/* set backlight brightness to level in range [0..max], assuming hw min is
 * respected.
 */
void intel_backlight_set_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);

        drm_WARN_ON(&dev_priv->drm, 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, u32 level)
{
        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_backlight_set_pwm_level(old_conn_state, level);

        /*
         * 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 = intel_de_read(dev_priv, BLC_PWM_CPU_CTL2);
        if (tmp & BLM_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm,
                            "cpu backlight was enabled, disabling\n");
                intel_de_write(dev_priv, BLC_PWM_CPU_CTL2,
                               tmp & ~BLM_PWM_ENABLE);
        }

        tmp = intel_de_read(dev_priv, BLC_PWM_PCH_CTL1);
        intel_de_write(dev_priv, BLC_PWM_PCH_CTL1, tmp & ~BLM_PCH_PWM_ENABLE);
}

static void pch_disable_backlight(const struct drm_connector_state *old_conn_state, u32 val)
{
        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_backlight_set_pwm_level(old_conn_state, val);

        tmp = intel_de_read(dev_priv, BLC_PWM_CPU_CTL2);
        intel_de_write(dev_priv, BLC_PWM_CPU_CTL2, tmp & ~BLM_PWM_ENABLE);

        tmp = intel_de_read(dev_priv, BLC_PWM_PCH_CTL1);
        intel_de_write(dev_priv, BLC_PWM_PCH_CTL1, tmp & ~BLM_PCH_PWM_ENABLE);
}

static void i9xx_disable_backlight(const struct drm_connector_state *old_conn_state, u32 val)
{
        intel_backlight_set_pwm_level(old_conn_state, val);
}

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

        intel_backlight_set_pwm_level(old_conn_state, val);

        tmp = intel_de_read(dev_priv, BLC_PWM_CTL2);
        intel_de_write(dev_priv, BLC_PWM_CTL2, tmp & ~BLM_PWM_ENABLE);
}

static void vlv_disable_backlight(const struct drm_connector_state *old_conn_state, u32 val)
{
        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_backlight_set_pwm_level(old_conn_state, val);

        tmp = intel_de_read(dev_priv, VLV_BLC_PWM_CTL2(pipe));
        intel_de_write(dev_priv, VLV_BLC_PWM_CTL2(pipe),
                       tmp & ~BLM_PWM_ENABLE);
}

static void bxt_disable_backlight(const struct drm_connector_state *old_conn_state, u32 val)
{
        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_backlight_set_pwm_level(old_conn_state, val);

        tmp = intel_de_read(dev_priv,
                            BXT_BLC_PWM_CTL(panel->backlight.controller));
        intel_de_write(dev_priv, BXT_BLC_PWM_CTL(panel->backlight.controller),
                       tmp & ~BXT_BLC_PWM_ENABLE);

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

static void cnp_disable_backlight(const struct drm_connector_state *old_conn_state, u32 val)
{
        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_backlight_set_pwm_level(old_conn_state, val);

        tmp = intel_de_read(dev_priv,
                            BXT_BLC_PWM_CTL(panel->backlight.controller));
        intel_de_write(dev_priv, BXT_BLC_PWM_CTL(panel->backlight.controller),
                       tmp & ~BXT_BLC_PWM_ENABLE);
}

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

        intel_backlight_set_pwm_level(old_conn_state, level);

        panel->backlight.pwm_state.enabled = false;
        pwm_apply_state(panel->backlight.pwm, &panel->backlight.pwm_state);
}

void intel_backlight_disable(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_dbg_kms(&dev_priv->drm,
                            "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.funcs->disable(old_conn_state, 0);

        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, 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 pch_ctl1, pch_ctl2, schicken;

        pch_ctl1 = intel_de_read(dev_priv, BLC_PWM_PCH_CTL1);
        if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm, "pch backlight already enabled\n");
                pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
                intel_de_write(dev_priv, BLC_PWM_PCH_CTL1, pch_ctl1);
        }

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

        pch_ctl2 = panel->backlight.pwm_level_max << 16;
        intel_de_write(dev_priv, 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;

        intel_de_write(dev_priv, BLC_PWM_PCH_CTL1, pch_ctl1);
        intel_de_posting_read(dev_priv, BLC_PWM_PCH_CTL1);
        intel_de_write(dev_priv, BLC_PWM_PCH_CTL1,
                       pch_ctl1 | BLM_PCH_PWM_ENABLE);

        /* This won't stick until the above enable. */
        intel_backlight_set_pwm_level(conn_state, level);
}

static void pch_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 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;
        enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
        u32 cpu_ctl2, pch_ctl1, pch_ctl2;

        cpu_ctl2 = intel_de_read(dev_priv, BLC_PWM_CPU_CTL2);
        if (cpu_ctl2 & BLM_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm, "cpu backlight already enabled\n");
                cpu_ctl2 &= ~BLM_PWM_ENABLE;
                intel_de_write(dev_priv, BLC_PWM_CPU_CTL2, cpu_ctl2);
        }

        pch_ctl1 = intel_de_read(dev_priv, BLC_PWM_PCH_CTL1);
        if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm, "pch backlight already enabled\n");
                pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
                intel_de_write(dev_priv, BLC_PWM_PCH_CTL1, pch_ctl1);
        }

        if (cpu_transcoder == TRANSCODER_EDP)
                cpu_ctl2 = BLM_TRANSCODER_EDP;
        else
                cpu_ctl2 = BLM_PIPE(cpu_transcoder);
        intel_de_write(dev_priv, BLC_PWM_CPU_CTL2, cpu_ctl2);
        intel_de_posting_read(dev_priv, BLC_PWM_CPU_CTL2);
        intel_de_write(dev_priv, BLC_PWM_CPU_CTL2, cpu_ctl2 | BLM_PWM_ENABLE);

        /* This won't stick until the above enable. */
        intel_backlight_set_pwm_level(conn_state, level);

        pch_ctl2 = panel->backlight.pwm_level_max << 16;
        intel_de_write(dev_priv, BLC_PWM_PCH_CTL2, pch_ctl2);

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

        intel_de_write(dev_priv, BLC_PWM_PCH_CTL1, pch_ctl1);
        intel_de_posting_read(dev_priv, BLC_PWM_PCH_CTL1);
        intel_de_write(dev_priv, 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, 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 ctl, freq;

        ctl = intel_de_read(dev_priv, BLC_PWM_CTL);
        if (ctl & BACKLIGHT_DUTY_CYCLE_MASK_PNV) {
                drm_dbg_kms(&dev_priv->drm, "backlight already enabled\n");
                intel_de_write(dev_priv, BLC_PWM_CTL, 0);
        }

        freq = panel->backlight.pwm_level_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;

        intel_de_write(dev_priv, BLC_PWM_CTL, ctl);
        intel_de_posting_read(dev_priv, BLC_PWM_CTL);

        /* XXX: combine this into above write? */
        intel_backlight_set_pwm_level(conn_state, 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 (DISPLAY_VER(dev_priv) == 2)
                intel_de_write(dev_priv, 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, 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;
        enum pipe pipe = to_intel_crtc(conn_state->crtc)->pipe;
        u32 ctl, ctl2, freq;

        ctl2 = intel_de_read(dev_priv, BLC_PWM_CTL2);
        if (ctl2 & BLM_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm, "backlight already enabled\n");
                ctl2 &= ~BLM_PWM_ENABLE;
                intel_de_write(dev_priv, BLC_PWM_CTL2, ctl2);
        }

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

        ctl = freq << 16;
        intel_de_write(dev_priv, 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;
        intel_de_write(dev_priv, BLC_PWM_CTL2, ctl2);
        intel_de_posting_read(dev_priv, BLC_PWM_CTL2);
        intel_de_write(dev_priv, BLC_PWM_CTL2, ctl2 | BLM_PWM_ENABLE);

        intel_backlight_set_pwm_level(conn_state, level);
}

static void vlv_enable_backlight(const struct intel_crtc_state *crtc_state,
                                 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;
        enum pipe pipe = to_intel_crtc(crtc_state->uapi.crtc)->pipe;
        u32 ctl, ctl2;

        ctl2 = intel_de_read(dev_priv, VLV_BLC_PWM_CTL2(pipe));
        if (ctl2 & BLM_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm, "backlight already enabled\n");
                ctl2 &= ~BLM_PWM_ENABLE;
                intel_de_write(dev_priv, VLV_BLC_PWM_CTL2(pipe), ctl2);
        }

        ctl = panel->backlight.pwm_level_max << 16;
        intel_de_write(dev_priv, VLV_BLC_PWM_CTL(pipe), ctl);

        /* XXX: combine this into above write? */
        intel_backlight_set_pwm_level(conn_state, level);

        ctl2 = 0;
        if (panel->backlight.active_low_pwm)
                ctl2 |= BLM_POLARITY_I965;
        intel_de_write(dev_priv, VLV_BLC_PWM_CTL2(pipe), ctl2);
        intel_de_posting_read(dev_priv, VLV_BLC_PWM_CTL2(pipe));
        intel_de_write(dev_priv, 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, 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;
        enum pipe pipe = to_intel_crtc(crtc_state->uapi.crtc)->pipe;
        u32 pwm_ctl, val;

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

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

        pwm_ctl = intel_de_read(dev_priv,
                                BXT_BLC_PWM_CTL(panel->backlight.controller));
        if (pwm_ctl & BXT_BLC_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm, "backlight already enabled\n");
                pwm_ctl &= ~BXT_BLC_PWM_ENABLE;
                intel_de_write(dev_priv,
                               BXT_BLC_PWM_CTL(panel->backlight.controller),
                               pwm_ctl);
        }

        intel_de_write(dev_priv,
                       BXT_BLC_PWM_FREQ(panel->backlight.controller),
                       panel->backlight.pwm_level_max);

        intel_backlight_set_pwm_level(conn_state, level);

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

        intel_de_write(dev_priv, BXT_BLC_PWM_CTL(panel->backlight.controller),
                       pwm_ctl);
        intel_de_posting_read(dev_priv,
                              BXT_BLC_PWM_CTL(panel->backlight.controller));
        intel_de_write(dev_priv, 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, 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 pwm_ctl;

        pwm_ctl = intel_de_read(dev_priv,
                                BXT_BLC_PWM_CTL(panel->backlight.controller));
        if (pwm_ctl & BXT_BLC_PWM_ENABLE) {
                drm_dbg_kms(&dev_priv->drm, "backlight already enabled\n");
                pwm_ctl &= ~BXT_BLC_PWM_ENABLE;
                intel_de_write(dev_priv,
                               BXT_BLC_PWM_CTL(panel->backlight.controller),
                               pwm_ctl);
        }

        intel_de_write(dev_priv,
                       BXT_BLC_PWM_FREQ(panel->backlight.controller),
                       panel->backlight.pwm_level_max);

        intel_backlight_set_pwm_level(conn_state, level);

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

        intel_de_write(dev_priv, BXT_BLC_PWM_CTL(panel->backlight.controller),
                       pwm_ctl);
        intel_de_posting_read(dev_priv,
                              BXT_BLC_PWM_CTL(panel->backlight.controller));
        intel_de_write(dev_priv, BXT_BLC_PWM_CTL(panel->backlight.controller),
                       pwm_ctl | BXT_BLC_PWM_ENABLE);
}

static void ext_pwm_enable_backlight(const struct intel_crtc_state *crtc_state,
                                     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;

        pwm_set_relative_duty_cycle(&panel->backlight.pwm_state, level, 100);
        panel->backlight.pwm_state.enabled = true;
        pwm_apply_state(panel->backlight.pwm, &panel->backlight.pwm_state);
}

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

void intel_backlight_enable(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->uapi.crtc)->pipe;

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

        drm_dbg_kms(&dev_priv->drm, "pipe %c\n", pipe_name(pipe));

        mutex_lock(&dev_priv->backlight_lock);

        __intel_backlight_enable(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.funcs->get(connector, intel_connector_get_pipe(connector));

        mutex_unlock(&dev_priv->backlight_lock);

        drm_dbg_kms(&dev_priv->drm, "get backlight PWM = %d\n", val);
        return val;
}

/* Scale user_level in range [0..user_max] to [hw_min..hw_max]. */
static 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);
}

/* 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);

        drm_WARN_ON(&dev_priv->drm, 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 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->runtime_pm, 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 drm_i915_private *i915 = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        struct backlight_properties props;
        struct backlight_device *bd;
        const char *name;
        int ret = 0;

        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;

        name = kstrdup("intel_backlight", GFP_KERNEL);
        if (!name)
                return -ENOMEM;

        bd = backlight_device_register(name, connector->base.kdev, connector,
                                       &intel_backlight_device_ops, &props);

        /*
         * Using the same name independent of the drm device or connector
         * prevents registration of multiple backlight devices in the
         * driver. However, we need to use the default name for backward
         * compatibility. Use unique names for subsequent backlight devices as a
         * fallback when the default name already exists.
         */
        if (IS_ERR(bd) && PTR_ERR(bd) == -EEXIST) {
                kfree(name);
                name = kasprintf(GFP_KERNEL, "card%d-%s-backlight",
                                 i915->drm.primary->index, connector->base.name);
                if (!name)
                        return -ENOMEM;

                bd = backlight_device_register(name, connector->base.kdev, connector,
                                               &intel_backlight_device_ops, &props);
        }

        if (IS_ERR(bd)) {
                drm_err(&i915->drm,
                        "[CONNECTOR:%d:%s] backlight device %s register failed: %ld\n",
                        connector->base.base.id, connector->base.name, name, PTR_ERR(bd));
                ret = PTR_ERR(bd);
                goto out;
        }

        panel->backlight.device = bd;

        drm_dbg_kms(&i915->drm,
                    "[CONNECTOR:%d:%s] backlight device %s registered\n",
                    connector->base.base.id, connector->base.name, name);

out:
        kfree(name);

        return ret;
}

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(RUNTIME_INFO(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(RUNTIME_INFO(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(RUNTIME_INFO(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(RUNTIME_INFO(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 ((intel_de_read(dev_priv, 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(RUNTIME_INFO(dev_priv)->rawclk_freq);
                mul = 128;
        }

        return DIV_ROUND_CLOSEST(clock, pwm_freq_hz * mul);
}

static u16 get_vbt_pwm_freq(struct drm_i915_private *dev_priv)
{
        u16 pwm_freq_hz = dev_priv->vbt.backlight.pwm_freq_hz;

        if (pwm_freq_hz) {
                drm_dbg_kms(&dev_priv->drm,
                            "VBT defined backlight frequency %u Hz\n",
                            pwm_freq_hz);
        } else {
                pwm_freq_hz = 200;
                drm_dbg_kms(&dev_priv->drm,
                            "default backlight frequency %u Hz\n",
                            pwm_freq_hz);
        }

        return pwm_freq_hz;
}

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 = get_vbt_pwm_freq(dev_priv);
        u32 pwm;

        if (!panel->backlight.pwm_funcs->hz_to_pwm) {
                drm_dbg_kms(&dev_priv->drm,
                            "backlight frequency conversion not supported\n");
                return 0;
        }

        pwm = panel->backlight.pwm_funcs->hz_to_pwm(connector, pwm_freq_hz);
        if (!pwm) {
                drm_dbg_kms(&dev_priv->drm,
                            "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;

        drm_WARN_ON(&dev_priv->drm, panel->backlight.pwm_level_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_dbg_kms(&dev_priv->drm,
                            "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.pwm_level_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 = intel_de_read(dev_priv, SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY;
        else
                alt = intel_de_read(dev_priv, SOUTH_CHICKEN1) & SPT_PWM_GRANULARITY;
        panel->backlight.alternate_pwm_increment = alt;

        pch_ctl1 = intel_de_read(dev_priv, BLC_PWM_PCH_CTL1);
        panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;

        pch_ctl2 = intel_de_read(dev_priv, BLC_PWM_PCH_CTL2);
        panel->backlight.pwm_level_max = pch_ctl2 >> 16;

        cpu_ctl2 = intel_de_read(dev_priv, BLC_PWM_CPU_CTL2);

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

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

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

        panel->backlight.pwm_enabled = pch_ctl1 & BLM_PCH_PWM_ENABLE;

        cpu_mode = panel->backlight.pwm_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, unused);

                drm_dbg_kms(&dev_priv->drm,
                            "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, val);
                intel_de_write(dev_priv, BLC_PWM_PCH_CTL1,
                               pch_ctl1 | BLM_PCH_OVERRIDE_ENABLE);

                intel_de_write(dev_priv, 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;

        pch_ctl1 = intel_de_read(dev_priv, BLC_PWM_PCH_CTL1);
        panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;

        pch_ctl2 = intel_de_read(dev_priv, BLC_PWM_PCH_CTL2);
        panel->backlight.pwm_level_max = pch_ctl2 >> 16;

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

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

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

        cpu_ctl2 = intel_de_read(dev_priv, BLC_PWM_CPU_CTL2);
        panel->backlight.pwm_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 = intel_de_read(dev_priv, BLC_PWM_CTL);

        if (DISPLAY_VER(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.pwm_level_max = ctl >> 17;

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

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

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

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

        val = i9xx_get_backlight(connector, unused);
        val = intel_backlight_invert_pwm_level(connector, val);
        val = clamp(val, panel->backlight.pwm_level_min, panel->backlight.pwm_level_max);

        panel->backlight.pwm_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;

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

        ctl = intel_de_read(dev_priv, BLC_PWM_CTL);
        panel->backlight.pwm_level_max = ctl >> 16;

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

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

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

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

        panel->backlight.pwm_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;

        if (drm_WARN_ON(&dev_priv->drm, pipe != PIPE_A && pipe != PIPE_B))
                return -ENODEV;

        ctl2 = intel_de_read(dev_priv, VLV_BLC_PWM_CTL2(pipe));
        panel->backlight.active_low_pwm = ctl2 & BLM_POLARITY_I965;

        ctl = intel_de_read(dev_priv, VLV_BLC_PWM_CTL(pipe));
        panel->backlight.pwm_level_max = ctl >> 16;

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

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

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

        panel->backlight.pwm_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 = intel_de_read(dev_priv,
                                BXT_BLC_PWM_CTL(panel->backlight.controller));

        /* Controller 1 uses the utility pin. */
        if (panel->backlight.controller == 1) {
                val = intel_de_read(dev_priv, 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.pwm_level_max =
                intel_de_read(dev_priv, BXT_BLC_PWM_FREQ(panel->backlight.controller));

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

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

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

        panel->backlight.pwm_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;

        /*
         * 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 = intel_de_read(dev_priv,
                                BXT_BLC_PWM_CTL(panel->backlight.controller));

        panel->backlight.active_low_pwm = pwm_ctl & BXT_BLC_PWM_POLARITY;
        panel->backlight.pwm_level_max =
                intel_de_read(dev_priv, BXT_BLC_PWM_FREQ(panel->backlight.controller));

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

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

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

        panel->backlight.pwm_enabled = pwm_ctl & BXT_BLC_PWM_ENABLE;

        return 0;
}

static int ext_pwm_setup_backlight(struct intel_connector *connector,
                                   enum pipe pipe)
{
        struct drm_device *dev = connector->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct intel_panel *panel = &connector->panel;
        const char *desc;
        u32 level;

        /* Get the right PWM chip for DSI backlight according to VBT */
        if (dev_priv->vbt.dsi.config->pwm_blc == PPS_BLC_PMIC) {
                panel->backlight.pwm = pwm_get(dev->dev, "pwm_pmic_backlight");
                desc = "PMIC";
        } else {
                panel->backlight.pwm = pwm_get(dev->dev, "pwm_soc_backlight");
                desc = "SoC";
        }

        if (IS_ERR(panel->backlight.pwm)) {
                drm_err(&dev_priv->drm, "Failed to get the %s PWM chip\n",
                        desc);
                panel->backlight.pwm = NULL;
                return -ENODEV;
        }

        panel->backlight.pwm_level_max = 100; /* 100% */
        panel->backlight.pwm_level_min = get_backlight_min_vbt(connector);

        if (pwm_is_enabled(panel->backlight.pwm)) {
                /* PWM is already enabled, use existing settings */
                pwm_get_state(panel->backlight.pwm, &panel->backlight.pwm_state);

                level = pwm_get_relative_duty_cycle(&panel->backlight.pwm_state,
                                                    100);
                level = intel_backlight_invert_pwm_level(connector, level);
                panel->backlight.pwm_enabled = true;

                drm_dbg_kms(&dev_priv->drm, "PWM already enabled at freq %ld, VBT freq %d, level %d\n",
                            NSEC_PER_SEC / (unsigned long)panel->backlight.pwm_state.period,
                            get_vbt_pwm_freq(dev_priv), level);
        } else {
                /* Set period from VBT frequency, leave other settings at 0. */
                panel->backlight.pwm_state.period =
                        NSEC_PER_SEC / get_vbt_pwm_freq(dev_priv);
        }

        drm_info(&dev_priv->drm, "Using %s PWM for LCD backlight control\n",
                 desc);
        return 0;
}

static void intel_pwm_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;

        panel->backlight.pwm_funcs->set(conn_state,
                                        intel_backlight_invert_pwm_level(connector, level));
}

static u32 intel_pwm_get_backlight(struct intel_connector *connector, enum pipe pipe)
{
        struct intel_panel *panel = &connector->panel;

        return intel_backlight_invert_pwm_level(connector,
                                            panel->backlight.pwm_funcs->get(connector, pipe));
}

static void intel_pwm_enable_backlight(const struct intel_crtc_state *crtc_state,
                                       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;

        panel->backlight.pwm_funcs->enable(crtc_state, conn_state,
                                           intel_backlight_invert_pwm_level(connector, level));
}

static void intel_pwm_disable_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;

        panel->backlight.pwm_funcs->disable(conn_state,
                                            intel_backlight_invert_pwm_level(connector, level));
}

static int intel_pwm_setup_backlight(struct intel_connector *connector, enum pipe pipe)
{
        struct intel_panel *panel = &connector->panel;
        int ret = panel->backlight.pwm_funcs->setup(connector, pipe);

        if (ret < 0)
                return ret;

        panel->backlight.min = panel->backlight.pwm_level_min;
        panel->backlight.max = panel->backlight.pwm_level_max;
        panel->backlight.level = intel_pwm_get_backlight(connector, pipe);
        panel->backlight.enabled = panel->backlight.pwm_enabled;

        return 0;
}

void intel_backlight_update(struct intel_atomic_state *state,
                            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_backlight_enable(crtc_state, conn_state);

        mutex_unlock(&dev_priv->backlight_lock);
}

int intel_backlight_setup(struct intel_connector *connector, enum pipe pipe)
{
        struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
        struct intel_panel *panel = &connector->panel;
        int ret;

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

        /* ensure intel_panel has been initialized first */
        if (drm_WARN_ON(&dev_priv->drm, !panel->backlight.funcs))
                return -ENODEV;

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

        if (ret) {
                drm_dbg_kms(&dev_priv->drm,
                            "failed to setup backlight for connector %s\n",
                            connector->base.name);
                return ret;
        }

        panel->backlight.present = true;

        drm_dbg_kms(&dev_priv->drm,
                    "Connector %s backlight initialized, %s, brightness %u/%u\n",
                    connector->base.name,
                    str_enabled_disabled(panel->backlight.enabled),
                    panel->backlight.level, panel->backlight.max);

        return 0;
}

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

        panel->backlight.present = false;
}

static const struct intel_panel_bl_funcs bxt_pwm_funcs = {
        .setup = bxt_setup_backlight,
        .enable = bxt_enable_backlight,
        .disable = bxt_disable_backlight,
        .set = bxt_set_backlight,
        .get = bxt_get_backlight,
        .hz_to_pwm = bxt_hz_to_pwm,
};

static const struct intel_panel_bl_funcs cnp_pwm_funcs = {
        .setup = cnp_setup_backlight,
        .enable = cnp_enable_backlight,
        .disable = cnp_disable_backlight,
        .set = bxt_set_backlight,
        .get = bxt_get_backlight,
        .hz_to_pwm = cnp_hz_to_pwm,
};

static const struct intel_panel_bl_funcs lpt_pwm_funcs = {
        .setup = lpt_setup_backlight,
        .enable = lpt_enable_backlight,
        .disable = lpt_disable_backlight,
        .set = lpt_set_backlight,
        .get = lpt_get_backlight,
        .hz_to_pwm = lpt_hz_to_pwm,
};

static const struct intel_panel_bl_funcs spt_pwm_funcs = {
        .setup = lpt_setup_backlight,
        .enable = lpt_enable_backlight,
        .disable = lpt_disable_backlight,
        .set = lpt_set_backlight,
        .get = lpt_get_backlight,
        .hz_to_pwm = spt_hz_to_pwm,
};

static const struct intel_panel_bl_funcs pch_pwm_funcs = {
        .setup = pch_setup_backlight,
        .enable = pch_enable_backlight,
        .disable = pch_disable_backlight,
        .set = pch_set_backlight,
        .get = pch_get_backlight,
        .hz_to_pwm = pch_hz_to_pwm,
};

static const struct intel_panel_bl_funcs ext_pwm_funcs = {
        .setup = ext_pwm_setup_backlight,
        .enable = ext_pwm_enable_backlight,
        .disable = ext_pwm_disable_backlight,
        .set = ext_pwm_set_backlight,
        .get = ext_pwm_get_backlight,
};

static const struct intel_panel_bl_funcs vlv_pwm_funcs = {
        .setup = vlv_setup_backlight,
        .enable = vlv_enable_backlight,
        .disable = vlv_disable_backlight,
        .set = vlv_set_backlight,
        .get = vlv_get_backlight,
        .hz_to_pwm = vlv_hz_to_pwm,
};

static const struct intel_panel_bl_funcs i965_pwm_funcs = {
        .setup = i965_setup_backlight,
        .enable = i965_enable_backlight,
        .disable = i965_disable_backlight,
        .set = i9xx_set_backlight,
        .get = i9xx_get_backlight,
        .hz_to_pwm = i965_hz_to_pwm,
};

static const struct intel_panel_bl_funcs i9xx_pwm_funcs = {
        .setup = i9xx_setup_backlight,
        .enable = i9xx_enable_backlight,
        .disable = i9xx_disable_backlight,
        .set = i9xx_set_backlight,
        .get = i9xx_get_backlight,
        .hz_to_pwm = i9xx_hz_to_pwm,
};

static const struct intel_panel_bl_funcs pwm_bl_funcs = {
        .setup = intel_pwm_setup_backlight,
        .enable = intel_pwm_enable_backlight,
        .disable = intel_pwm_disable_backlight,
        .set = intel_pwm_set_backlight,
        .get = intel_pwm_get_backlight,
};

/* Set up chip specific backlight functions */
void intel_backlight_init_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_DSI &&
            intel_dsi_dcs_init_backlight_funcs(connector) == 0)
                return;

        if (IS_GEMINILAKE(dev_priv) || IS_BROXTON(dev_priv)) {
                panel->backlight.pwm_funcs = &bxt_pwm_funcs;
        } else if (INTEL_PCH_TYPE(dev_priv) >= PCH_CNP) {
                panel->backlight.pwm_funcs = &cnp_pwm_funcs;
        } else if (INTEL_PCH_TYPE(dev_priv) >= PCH_LPT) {
                if (HAS_PCH_LPT(dev_priv))
                        panel->backlight.pwm_funcs = &lpt_pwm_funcs;
                else
                        panel->backlight.pwm_funcs = &spt_pwm_funcs;
        } else if (HAS_PCH_SPLIT(dev_priv)) {
                panel->backlight.pwm_funcs = &pch_pwm_funcs;
        } else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
                if (connector->base.connector_type == DRM_MODE_CONNECTOR_DSI) {
                        panel->backlight.pwm_funcs = &ext_pwm_funcs;
                } else {
                        panel->backlight.pwm_funcs = &vlv_pwm_funcs;
                }
        } else if (DISPLAY_VER(dev_priv) == 4) {
                panel->backlight.pwm_funcs = &i965_pwm_funcs;
        } else {
                panel->backlight.pwm_funcs = &i9xx_pwm_funcs;
        }

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

        /* We're using a standard PWM backlight interface */
        panel->backlight.funcs = &pwm_bl_funcs;
}