drivers/gpu/drm/i915/display/intel_backlight.c

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

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

#include <acpi/video.h>

#include "i915_reg.h"
#include "intel_backlight.h"
#include "intel_backlight_regs.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"
#include "intel_pps.h"
#include "intel_quirks.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 intel_display *display = to_intel_display(connector);
	struct intel_panel *panel = &connector->panel;

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

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

	if (display->params.invert_brightness > 0 ||
	    intel_has_quirk(display, 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, "[CONNECTOR:%d:%s] set backlight PWM = %d\n",
		    connector->base.base.id, connector->base.name, 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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;

	drm_WARN_ON_ONCE(&i915->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 intel_display *display = to_intel_display(connector);
	struct intel_panel *panel = &connector->panel;

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

	if (display->params.invert_brightness > 0 ||
	    (display->params.invert_brightness == 0 &&
	     intel_has_quirk(display, 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 *i915 = to_i915(connector->base.dev);

	return intel_de_read(i915, BLC_PWM_PCH_CTL2) & BACKLIGHT_DUTY_CYCLE_MASK;
}

static u32 pch_get_backlight(struct intel_connector *connector, enum pipe unused)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);

	return intel_de_read(i915, BLC_PWM_CPU_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
}

static u32 i9xx_get_backlight(struct intel_connector *connector, enum pipe unused)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 val;

	val = intel_de_read(i915, BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
	if (DISPLAY_VER(i915) < 4)
		val >>= 1;

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

		pci_read_config_byte(to_pci_dev(i915->drm.dev), LBPC, &lbpc);
		val *= lbpc;
	}

	return val;
}

static u32 vlv_get_backlight(struct intel_connector *connector, enum pipe pipe)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);

	if (drm_WARN_ON(&i915->drm, pipe != PIPE_A && pipe != PIPE_B))
		return 0;

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

	return intel_de_read(i915, 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 *i915 = to_i915(connector->base.dev);
	u32 val;

	val = intel_de_read(i915, BLC_PWM_PCH_CTL2) & ~BACKLIGHT_DUTY_CYCLE_MASK;
	intel_de_write(i915, 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 *i915 = to_i915(connector->base.dev);
	u32 tmp;

	tmp = intel_de_read(i915, BLC_PWM_CPU_CTL) & ~BACKLIGHT_DUTY_CYCLE_MASK;
	intel_de_write(i915, 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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 tmp, mask;

	drm_WARN_ON(&i915->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(i915->drm.dev), LBPC, lbpc);
	}

	if (DISPLAY_VER(i915) == 4) {
		mask = BACKLIGHT_DUTY_CYCLE_MASK;
	} else {
		level <<= 1;
		mask = BACKLIGHT_DUTY_CYCLE_MASK_PNV;
	}

	tmp = intel_de_read(i915, BLC_PWM_CTL) & ~mask;
	intel_de_write(i915, 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 *i915 = to_i915(connector->base.dev);
	enum pipe pipe = to_intel_crtc(conn_state->crtc)->pipe;
	u32 tmp;

	tmp = intel_de_read(i915, VLV_BLC_PWM_CTL(pipe)) & ~BACKLIGHT_DUTY_CYCLE_MASK;
	intel_de_write(i915, 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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;

	intel_de_write(i915, 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_might_sleep(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, "[CONNECTOR:%d:%s] set backlight level = %d\n",
		    connector->base.base.id, connector->base.name, 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 *i915 = 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(&i915->display.backlight.lock);

	drm_WARN_ON(&i915->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(&i915->display.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 *i915 = 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(i915, BLC_PWM_CPU_CTL2);
	if (tmp & BLM_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] CPU backlight was enabled, disabling\n",
			    connector->base.base.id, connector->base.name);
		intel_de_write(i915, BLC_PWM_CPU_CTL2, tmp & ~BLM_PWM_ENABLE);
	}

	intel_de_rmw(i915, BLC_PWM_PCH_CTL1, BLM_PCH_PWM_ENABLE, 0);
}

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 *i915 = to_i915(connector->base.dev);

	intel_backlight_set_pwm_level(old_conn_state, val);

	intel_de_rmw(i915, BLC_PWM_CPU_CTL2, BLM_PWM_ENABLE, 0);

	intel_de_rmw(i915, BLC_PWM_PCH_CTL1, BLM_PCH_PWM_ENABLE, 0);
}

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 *i915 = to_i915(old_conn_state->connector->dev);

	intel_backlight_set_pwm_level(old_conn_state, val);

	intel_de_rmw(i915, BLC_PWM_CTL2, BLM_PWM_ENABLE, 0);
}

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 *i915 = to_i915(connector->base.dev);
	enum pipe pipe = to_intel_crtc(old_conn_state->crtc)->pipe;

	intel_backlight_set_pwm_level(old_conn_state, val);

	intel_de_rmw(i915, VLV_BLC_PWM_CTL2(pipe), BLM_PWM_ENABLE, 0);
}

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

	intel_backlight_set_pwm_level(old_conn_state, val);

	intel_de_rmw(i915, BXT_BLC_PWM_CTL(panel->backlight.controller),
		     BXT_BLC_PWM_ENABLE, 0);

	if (panel->backlight.controller == 1)
		intel_de_rmw(i915, UTIL_PIN_CTL, UTIL_PIN_ENABLE, 0);
}

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

	intel_backlight_set_pwm_level(old_conn_state, val);

	intel_de_rmw(i915, BXT_BLC_PWM_CTL(panel->backlight.controller),
		     BXT_BLC_PWM_ENABLE, 0);
}

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_might_sleep(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 *i915 = 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 (i915->drm.switch_power_state == DRM_SWITCH_POWER_CHANGING) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Skipping backlight disable on vga switch\n",
			    connector->base.base.id, connector->base.name);
		return;
	}

	mutex_lock(&i915->display.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(&i915->display.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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 pch_ctl1, pch_ctl2;

	pch_ctl1 = intel_de_read(i915, BLC_PWM_PCH_CTL1);
	if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] PCH backlight already enabled\n",
			    connector->base.base.id, connector->base.name);
		pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
		intel_de_write(i915, BLC_PWM_PCH_CTL1, pch_ctl1);
	}

	if (HAS_PCH_LPT(i915))
		intel_de_rmw(i915, SOUTH_CHICKEN2, LPT_PWM_GRANULARITY,
			     panel->backlight.alternate_pwm_increment ?
			     LPT_PWM_GRANULARITY : 0);
	else
		intel_de_rmw(i915, SOUTH_CHICKEN1, SPT_PWM_GRANULARITY,
			     panel->backlight.alternate_pwm_increment ?
			     SPT_PWM_GRANULARITY : 0);

	pch_ctl2 = panel->backlight.pwm_level_max << 16;
	intel_de_write(i915, 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(i915))
		pch_ctl1 |= BLM_PCH_OVERRIDE_ENABLE;

	intel_de_write(i915, BLC_PWM_PCH_CTL1, pch_ctl1);
	intel_de_posting_read(i915, BLC_PWM_PCH_CTL1);
	intel_de_write(i915, 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 *i915 = 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(i915, BLC_PWM_CPU_CTL2);
	if (cpu_ctl2 & BLM_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] CPU backlight already enabled\n",
			    connector->base.base.id, connector->base.name);
		cpu_ctl2 &= ~BLM_PWM_ENABLE;
		intel_de_write(i915, BLC_PWM_CPU_CTL2, cpu_ctl2);
	}

	pch_ctl1 = intel_de_read(i915, BLC_PWM_PCH_CTL1);
	if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] PCH backlight already enabled\n",
			    connector->base.base.id, connector->base.name);
		pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
		intel_de_write(i915, 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(i915, BLC_PWM_CPU_CTL2, cpu_ctl2);
	intel_de_posting_read(i915, BLC_PWM_CPU_CTL2);
	intel_de_write(i915, 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(i915, BLC_PWM_PCH_CTL2, pch_ctl2);

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

	intel_de_write(i915, BLC_PWM_PCH_CTL1, pch_ctl1);
	intel_de_posting_read(i915, BLC_PWM_PCH_CTL1);
	intel_de_write(i915, 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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 ctl, freq;

	ctl = intel_de_read(i915, BLC_PWM_CTL);
	if (ctl & BACKLIGHT_DUTY_CYCLE_MASK_PNV) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] backlight already enabled\n",
			    connector->base.base.id, connector->base.name);
		intel_de_write(i915, 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(i915) && panel->backlight.active_low_pwm)
		ctl |= BLM_POLARITY_PNV;

	intel_de_write(i915, BLC_PWM_CTL, ctl);
	intel_de_posting_read(i915, 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(i915) == 2)
		intel_de_write(i915, 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 *i915 = 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(i915, BLC_PWM_CTL2);
	if (ctl2 & BLM_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] backlight already enabled\n",
			    connector->base.base.id, connector->base.name);
		ctl2 &= ~BLM_PWM_ENABLE;
		intel_de_write(i915, BLC_PWM_CTL2, ctl2);
	}

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

	ctl = freq << 16;
	intel_de_write(i915, 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(i915, BLC_PWM_CTL2, ctl2);
	intel_de_posting_read(i915, BLC_PWM_CTL2);
	intel_de_write(i915, 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 *i915 = 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(i915, VLV_BLC_PWM_CTL2(pipe));
	if (ctl2 & BLM_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] backlight already enabled\n",
			    connector->base.base.id, connector->base.name);
		ctl2 &= ~BLM_PWM_ENABLE;
		intel_de_write(i915, VLV_BLC_PWM_CTL2(pipe), ctl2);
	}

	ctl = panel->backlight.pwm_level_max << 16;
	intel_de_write(i915, 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(i915, VLV_BLC_PWM_CTL2(pipe), ctl2);
	intel_de_posting_read(i915, VLV_BLC_PWM_CTL2(pipe));
	intel_de_write(i915, 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 *i915 = 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(i915, UTIL_PIN_CTL);
		if (val & UTIL_PIN_ENABLE) {
			drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] utility pin already enabled\n",
				    connector->base.base.id, connector->base.name);
			val &= ~UTIL_PIN_ENABLE;
			intel_de_write(i915, UTIL_PIN_CTL, val);
		}

		val = 0;
		if (panel->backlight.util_pin_active_low)
			val |= UTIL_PIN_POLARITY;
		intel_de_write(i915, UTIL_PIN_CTL,
			       val | UTIL_PIN_PIPE(pipe) | UTIL_PIN_MODE_PWM | UTIL_PIN_ENABLE);
	}

	pwm_ctl = intel_de_read(i915, BXT_BLC_PWM_CTL(panel->backlight.controller));
	if (pwm_ctl & BXT_BLC_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] backlight already enabled\n",
			    connector->base.base.id, connector->base.name);
		pwm_ctl &= ~BXT_BLC_PWM_ENABLE;
		intel_de_write(i915, BXT_BLC_PWM_CTL(panel->backlight.controller),
			       pwm_ctl);
	}

	intel_de_write(i915, 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(i915, BXT_BLC_PWM_CTL(panel->backlight.controller), pwm_ctl);
	intel_de_posting_read(i915, BXT_BLC_PWM_CTL(panel->backlight.controller));
	intel_de_write(i915, 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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 pwm_ctl;

	pwm_ctl = intel_de_read(i915, BXT_BLC_PWM_CTL(panel->backlight.controller));
	if (pwm_ctl & BXT_BLC_PWM_ENABLE) {
		drm_dbg_kms(&i915->drm, "backlight already enabled\n");
		pwm_ctl &= ~BXT_BLC_PWM_ENABLE;
		intel_de_write(i915, BXT_BLC_PWM_CTL(panel->backlight.controller),
			       pwm_ctl);
	}

	intel_de_write(i915, 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(i915, BXT_BLC_PWM_CTL(panel->backlight.controller), pwm_ctl);
	intel_de_posting_read(i915, BXT_BLC_PWM_CTL(panel->backlight.controller));
	intel_de_write(i915, 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_might_sleep(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.min;
		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 *i915 = 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(&i915->drm, "pipe %c\n", pipe_name(pipe));

	mutex_lock(&i915->display.backlight.lock);

	__intel_backlight_enable(crtc_state, conn_state);

	mutex_unlock(&i915->display.backlight.lock);
}

#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
static u32 intel_panel_get_backlight(struct intel_connector *connector)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 val = 0;

	mutex_lock(&i915->display.backlight.lock);

	if (panel->backlight.enabled)
		val = panel->backlight.funcs->get(connector, intel_connector_get_pipe(connector));

	mutex_unlock(&i915->display.backlight.lock);

	drm_dbg_kms(&i915->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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 hw_level;

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

	mutex_lock(&i915->display.backlight.lock);

	drm_WARN_ON(&i915->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(&i915->display.backlight.lock);
}

static int intel_backlight_device_update_status(struct backlight_device *bd)
{
	struct intel_connector *connector = bl_get_data(bd);
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;

	drm_modeset_lock(&i915->drm.mode_config.connection_mutex, NULL);

	drm_dbg_kms(&i915->drm, "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(&i915->drm.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_i915_private *i915 = to_i915(connector->base.dev);
	intel_wakeref_t wakeref;
	int ret = 0;

	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
		u32 hw_level;

		drm_modeset_lock(&i915->drm.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(&i915->drm.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);

	if (!acpi_video_backlight_use_native()) {
		drm_info(&i915->drm, "Skipping intel_backlight registration\n");
		return 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_const("intel_backlight", GFP_KERNEL);
	if (!name)
		return -ENOMEM;

	bd = backlight_device_get_by_name(name);
	if (bd) {
		put_device(&bd->dev);
		/*
		 * 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.
		 */
		kfree_const(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_const(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 *i915 = to_i915(connector->base.dev);

	return DIV_ROUND_CLOSEST(KHz(RUNTIME_INFO(i915)->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 *i915 = 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(i915))
		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 *i915 = to_i915(connector->base.dev);

	return DIV_ROUND_CLOSEST(KHz(RUNTIME_INFO(i915)->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 *i915 = to_i915(connector->base.dev);
	int clock;

	if (IS_PINEVIEW(i915))
		clock = KHz(RUNTIME_INFO(i915)->rawclk_freq);
	else
		clock = KHz(i915->display.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 *i915 = to_i915(connector->base.dev);
	int clock;

	if (IS_G4X(i915))
		clock = KHz(RUNTIME_INFO(i915)->rawclk_freq);
	else
		clock = KHz(i915->display.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 *i915 = to_i915(connector->base.dev);
	int mul, clock;

	if ((intel_de_read(i915, CBR1_VLV) & CBR_PWM_CLOCK_MUX_SELECT) == 0) {
		if (IS_CHERRYVIEW(i915))
			clock = KHz(19200);
		else
			clock = MHz(25);
		mul = 16;
	} else {
		clock = KHz(RUNTIME_INFO(i915)->rawclk_freq);
		mul = 128;
	}

	return DIV_ROUND_CLOSEST(clock, pwm_freq_hz * mul);
}

static u16 get_vbt_pwm_freq(struct intel_connector *connector)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	u16 pwm_freq_hz = connector->panel.vbt.backlight.pwm_freq_hz;

	if (pwm_freq_hz) {
		drm_dbg_kms(&i915->drm,
			    "VBT defined backlight frequency %u Hz\n",
			    pwm_freq_hz);
	} else {
		pwm_freq_hz = 200;
		drm_dbg_kms(&i915->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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u16 pwm_freq_hz = get_vbt_pwm_freq(connector);
	u32 pwm;

	if (!panel->backlight.pwm_funcs->hz_to_pwm) {
		drm_dbg_kms(&i915->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(&i915->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 *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	int min;

	drm_WARN_ON(&i915->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, connector->panel.vbt.backlight.min_brightness, 0, 64);
	if (min != connector->panel.vbt.backlight.min_brightness) {
		drm_dbg_kms(&i915->drm,
			    "clamping VBT min backlight %d/255 to %d/255\n",
			    connector->panel.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 *i915 = 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(i915))
		alt = intel_de_read(i915, SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY;
	else
		alt = intel_de_read(i915, SOUTH_CHICKEN1) & SPT_PWM_GRANULARITY;
	panel->backlight.alternate_pwm_increment = alt;

	pch_ctl1 = intel_de_read(i915, BLC_PWM_PCH_CTL1);
	panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;

	pch_ctl2 = intel_de_read(i915, BLC_PWM_PCH_CTL2);
	panel->backlight.pwm_level_max = pch_ctl2 >> 16;

	cpu_ctl2 = intel_de_read(i915, 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(i915) &&
		   !(pch_ctl1 & BLM_PCH_OVERRIDE_ENABLE) &&
		   (cpu_ctl2 & BLM_PWM_ENABLE);

	if (cpu_mode) {
		val = pch_get_backlight(connector, unused);

		drm_dbg_kms(&i915->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(i915, BLC_PWM_PCH_CTL1,
			       pch_ctl1 | BLM_PCH_OVERRIDE_ENABLE);

		intel_de_write(i915, BLC_PWM_CPU_CTL2,
			       cpu_ctl2 & ~BLM_PWM_ENABLE);
	}

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using native PCH PWM for backlight control\n",
		    connector->base.base.id, connector->base.name);

	return 0;
}

static int pch_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 cpu_ctl2, pch_ctl1, pch_ctl2;

	pch_ctl1 = intel_de_read(i915, BLC_PWM_PCH_CTL1);
	panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;

	pch_ctl2 = intel_de_read(i915, 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(i915, BLC_PWM_CPU_CTL2);
	panel->backlight.pwm_enabled = (cpu_ctl2 & BLM_PWM_ENABLE) &&
		(pch_ctl1 & BLM_PCH_PWM_ENABLE);

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using native PCH PWM for backlight control\n",
		    connector->base.base.id, connector->base.name);

	return 0;
}

static int i9xx_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 ctl, val;

	ctl = intel_de_read(i915, BLC_PWM_CTL);

	if (DISPLAY_VER(i915) == 2 || IS_I915GM(i915) || IS_I945GM(i915))
		panel->backlight.combination_mode = ctl & BLM_LEGACY_MODE;

	if (IS_PINEVIEW(i915))
		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;

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using native PWM for backlight control\n",
		    connector->base.base.id, connector->base.name);

	return 0;
}

static int i965_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 ctl, ctl2;

	ctl2 = intel_de_read(i915, BLC_PWM_CTL2);
	panel->backlight.combination_mode = ctl2 & BLM_COMBINATION_MODE;
	panel->backlight.active_low_pwm = ctl2 & BLM_POLARITY_I965;

	ctl = intel_de_read(i915, 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;

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using native PWM for backlight control\n",
		    connector->base.base.id, connector->base.name);

	return 0;
}

static int vlv_setup_backlight(struct intel_connector *connector, enum pipe pipe)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 ctl, ctl2;

	if (drm_WARN_ON(&i915->drm, pipe != PIPE_A && pipe != PIPE_B))
		return -ENODEV;

	ctl2 = intel_de_read(i915, VLV_BLC_PWM_CTL2(pipe));
	panel->backlight.active_low_pwm = ctl2 & BLM_POLARITY_I965;

	ctl = intel_de_read(i915, 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;

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using native PWM for backlight control (on pipe %c)\n",
		    connector->base.base.id, connector->base.name, pipe_name(pipe));

	return 0;
}

static int
bxt_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	u32 pwm_ctl, val;

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

	pwm_ctl = intel_de_read(i915,
				BXT_BLC_PWM_CTL(panel->backlight.controller));

	/* Controller 1 uses the utility pin. */
	if (panel->backlight.controller == 1) {
		val = intel_de_read(i915, 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(i915, 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;

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using native PWM for backlight control (controller=%d)\n",
		    connector->base.base.id, connector->base.name,
		    panel->backlight.controller);

	return 0;
}

static int cnp_num_backlight_controllers(struct drm_i915_private *i915)
{
	if (INTEL_PCH_TYPE(i915) >= PCH_DG1)
		return 1;

	if (INTEL_PCH_TYPE(i915) >= PCH_ICP)
		return 2;

	return 1;
}

static bool cnp_backlight_controller_is_valid(struct drm_i915_private *i915, int controller)
{
	if (controller < 0 || controller >= cnp_num_backlight_controllers(i915))
		return false;

	if (controller == 1 &&
	    INTEL_PCH_TYPE(i915) >= PCH_ICP &&
	    INTEL_PCH_TYPE(i915) <= PCH_ADP)
		return intel_de_read(i915, SOUTH_CHICKEN1) & ICP_SECOND_PPS_IO_SELECT;

	return true;
}

static int
cnp_setup_backlight(struct intel_connector *connector, enum pipe unused)
{
	struct drm_i915_private *i915 = 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. ICP+ can have two controllers, depending on pin muxing.
	 */
	panel->backlight.controller = connector->panel.vbt.backlight.controller;
	if (!cnp_backlight_controller_is_valid(i915, panel->backlight.controller)) {
		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Invalid backlight controller %d, assuming 0\n",
			    connector->base.base.id, connector->base.name,
			    panel->backlight.controller);
		panel->backlight.controller = 0;
	}

	pwm_ctl = intel_de_read(i915,
				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(i915, 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;

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using native PCH PWM for backlight control (controller=%d)\n",
		    connector->base.base.id, connector->base.name,
		    panel->backlight.controller);

	return 0;
}

static int ext_pwm_setup_backlight(struct intel_connector *connector,
				   enum pipe pipe)
{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	const char *desc;
	u32 level;

	/* Get the right PWM chip for DSI backlight according to VBT */
	if (connector->panel.vbt.dsi.config->pwm_blc == PPS_BLC_PMIC) {
		panel->backlight.pwm = pwm_get(i915->drm.dev, "pwm_pmic_backlight");
		desc = "PMIC";
	} else {
		panel->backlight.pwm = pwm_get(i915->drm.dev, "pwm_soc_backlight");
		desc = "SoC";
	}

	if (IS_ERR(panel->backlight.pwm)) {
		drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to get the %s PWM chip\n",
			connector->base.base.id, connector->base.name, 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(&i915->drm, "[CONNECTOR:%d:%s] PWM already enabled at freq %ld, VBT freq %d, level %d\n",
			    connector->base.base.id, connector->base.name,
			    NSEC_PER_SEC / (unsigned long)panel->backlight.pwm_state.period,
			    get_vbt_pwm_freq(connector), level);
	} else {
		/* Set period from VBT frequency, leave other settings at 0. */
		panel->backlight.pwm_state.period =
			NSEC_PER_SEC / get_vbt_pwm_freq(connector);
	}

	drm_dbg_kms(&i915->drm,
		    "[CONNECTOR:%d:%s] Using %s PWM for backlight control\n",
		    connector->base.base.id, connector->base.name, 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;

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

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

	mutex_lock(&i915->display.backlight.lock);
	if (!panel->backlight.enabled)
		__intel_backlight_enable(crtc_state, conn_state);

	mutex_unlock(&i915->display.backlight.lock);
}

int intel_backlight_setup(struct intel_connector *connector, enum pipe pipe)
{
	struct intel_display *display = to_intel_display(connector);
	struct intel_panel *panel = &connector->panel;
	int ret;

	if (!connector->panel.vbt.backlight.present) {
		if (intel_has_quirk(display, QUIRK_BACKLIGHT_PRESENT)) {
			drm_dbg_kms(display->drm,
				    "[CONNECTOR:%d:%s] no backlight present per VBT, but present per quirk\n",
				    connector->base.base.id, connector->base.name);
		} else {
			drm_dbg_kms(display->drm,
				    "[CONNECTOR:%d:%s] no backlight present per VBT\n",
				    connector->base.base.id, connector->base.name);
			return 0;
		}
	}

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

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

	if (ret) {
		drm_dbg_kms(display->drm,
			    "[CONNECTOR:%d:%s] failed to setup backlight\n",
			    connector->base.base.id, connector->base.name);
		return ret;
	}

	panel->backlight.present = true;

	drm_dbg_kms(display->drm,
		    "[CONNECTOR:%d:%s] backlight initialized, %s, brightness %u/%u\n",
		    connector->base.base.id, 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 *i915 = 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(i915) || IS_BROXTON(i915)) {
		panel->backlight.pwm_funcs = &bxt_pwm_funcs;
	} else if (INTEL_PCH_TYPE(i915) >= PCH_CNP) {
		panel->backlight.pwm_funcs = &cnp_pwm_funcs;
	} else if (INTEL_PCH_TYPE(i915) >= PCH_LPT) {
		if (HAS_PCH_LPT(i915))
			panel->backlight.pwm_funcs = &lpt_pwm_funcs;
		else
			panel->backlight.pwm_funcs = &spt_pwm_funcs;
	} else if (HAS_PCH_SPLIT(i915)) {
		panel->backlight.pwm_funcs = &pch_pwm_funcs;
	} else if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915)) {
		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(i915) == 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) {
		if (intel_dp_aux_init_backlight_funcs(connector) == 0)
			return;

		if (!intel_has_quirk(&i915->display, QUIRK_NO_PPS_BACKLIGHT_POWER_HOOK))
			connector->panel.backlight.power = intel_pps_backlight_power;
	}

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