[PATCH 8/8] drm/i915: Backlight control using CRC PMIC based PWM driver

[Shobhit Kumar <shobhit.kumar@xxxxxxxxx>]

Use the CRC PWM device in intel_panel.c and add new MIPI backlight
specififc callbacks

v2: Modify to use pwm_config callback

CC: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Alexandre Courbot <gnurou@xxxxxxxxx>
Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
Signed-off-by: Shobhit Kumar <shobhit.kumar@xxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_drv.h   |  5 +++
 drivers/gpu/drm/i915/intel_dsi.c   |  6 +++
 drivers/gpu/drm/i915/intel_panel.c | 92 +++++++++++++++++++++++++++++++++++---
 3 files changed, 98 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 897f17d..b4ebe3b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -182,7 +182,12 @@ struct intel_panel {
 		bool enabled;
 		bool combination_mode;	/* gen 2/4 only */
 		bool active_low_pwm;
+
+		/* PWM chip */
+		struct pwm_device *pwm;
+
 		struct backlight_device *device;
+
 	} backlight;
 
 	void (*backlight_power)(struct intel_connector *, bool enable);
diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index be55ffa..83c4540 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -402,6 +402,8 @@ static void intel_dsi_enable(struct intel_encoder *encoder)
 
 		intel_dsi_port_enable(encoder);
 	}
+
+	intel_panel_enable_backlight(intel_dsi->attached_connector);
 }
 
 static void intel_dsi_pre_enable(struct intel_encoder *encoder)
@@ -466,6 +468,8 @@ static void intel_dsi_pre_disable(struct intel_encoder *encoder)
 
 	DRM_DEBUG_KMS("\n");
 
+	intel_panel_disable_backlight(intel_dsi->attached_connector);
+
 	if (is_vid_mode(intel_dsi)) {
 		/* Send Shutdown command to the panel in LP mode */
 		for_each_dsi_port(port, intel_dsi->ports)
@@ -1132,6 +1136,8 @@ void intel_dsi_init(struct drm_device *dev)
 	}
 
 	intel_panel_init(&intel_connector->panel, fixed_mode, NULL);
+	intel_panel_setup_backlight(connector,
+		(intel_encoder->crtc_mask = (1 << PIPE_A)) ? PIPE_A: PIPE_B);
 
 	return;
 
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 08532d4..5700f6f 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -32,8 +32,12 @@
 
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
+#include <linux/pwm.h>
 #include "intel_drv.h"
 
+#define CRC_PMIC_PWM_PERIOD_NS	21333
+#define CRC_PMIC_PWM_STEPS	255
+
 void
 intel_fixed_panel_mode(const struct drm_display_mode *fixed_mode,
 		       struct drm_display_mode *adjusted_mode)
@@ -536,6 +540,15 @@ static u32 vlv_get_backlight(struct intel_connector *connector)
 	return _vlv_get_backlight(dev, pipe);
 }
 
+static u32 vlv_get_mipi_backlight(struct intel_connector *connector)
+{
+	struct intel_panel *panel = &connector->panel;
+	int duty_ns;
+
+	duty_ns = pwm_get_duty_cycle(panel->backlight.pwm);
+	return DIV_ROUND_UP(duty_ns * 100, CRC_PMIC_PWM_PERIOD_NS);
+}
+
 static u32 intel_panel_get_backlight(struct intel_connector *connector)
 {
 	struct drm_device *dev = connector->base.dev;
@@ -616,6 +629,14 @@ static void vlv_set_backlight(struct intel_connector *connector, u32 level)
 	I915_WRITE(VLV_BLC_PWM_CTL(pipe), tmp | level);
 }
 
+static void vlv_set_mipi_backlight(struct intel_connector *connector, u32 level)
+{
+	struct intel_panel *panel = &connector->panel;
+	int duty_ns = DIV_ROUND_UP(level * CRC_PMIC_PWM_PERIOD_NS, 100);
+
+	pwm_config(panel->backlight.pwm, duty_ns, CRC_PMIC_PWM_PERIOD_NS);
+}
+
 static void
 intel_panel_actually_set_backlight(struct intel_connector *connector, u32 level)
 {
@@ -741,6 +762,16 @@ static void vlv_disable_backlight(struct intel_connector *connector)
 	I915_WRITE(VLV_BLC_PWM_CTL2(pipe), tmp & ~BLM_PWM_ENABLE);
 }
 
+static void vlv_disable_mipi_backlight(struct intel_connector *connector)
+{
+	struct intel_panel *panel = &connector->panel;
+
+	/* Disable the backlight */
+	pwm_config(panel->backlight.pwm, 0, CRC_PMIC_PWM_PERIOD_NS);
+	usleep_range(2000, 3000);
+	pwm_disable(panel->backlight.pwm);
+}
+
 void intel_panel_disable_backlight(struct intel_connector *connector)
 {
 	struct drm_device *dev = connector->base.dev;
@@ -947,6 +978,16 @@ static void vlv_enable_backlight(struct intel_connector *connector)
 	I915_WRITE(VLV_BLC_PWM_CTL2(pipe), ctl2 | BLM_PWM_ENABLE);
 }
 
+static void vlv_enable_mipi_backlight(struct intel_connector *connector)
+{
+	struct intel_panel *panel = &connector->panel;
+	int duty_ns = DIV_ROUND_UP(
+			panel->backlight.level * CRC_PMIC_PWM_PERIOD_NS, 100);
+
+	pwm_enable(panel->backlight.pwm);
+	pwm_config(panel->backlight.pwm, duty_ns, CRC_PMIC_PWM_PERIOD_NS);
+}
+
 void intel_panel_enable_backlight(struct intel_connector *connector)
 {
 	struct drm_device *dev = connector->base.dev;
@@ -1299,6 +1340,34 @@ static int vlv_setup_backlight(struct intel_connector *connector, enum pipe pipe
 	return 0;
 }
 
+static int vlv_setup_mipi_backlight(struct intel_connector *connector, enum pipe pipe)
+{
+	struct drm_device *dev = connector->base.dev;
+	struct intel_panel *panel = &connector->panel;
+
+	/* Get the PWM chip for backlight control */
+	panel->backlight.pwm = pwm_get(dev->dev, "pwm_backlight");
+	if (IS_ERR(panel->backlight.pwm)) {
+		DRM_ERROR("Faild to own the pwm chip\n");
+		panel->backlight.pwm = NULL;
+	} else if (pwm_config(panel->backlight.pwm, CRC_PMIC_PWM_PERIOD_NS,
+						CRC_PMIC_PWM_PERIOD_NS) < 0) {
+		DRM_ERROR("Failed to configure the pwm chip\n");
+		pwm_put(panel->backlight.pwm);
+		panel->backlight.pwm = NULL;
+		return -1;
+	}
+
+	panel->backlight.min = 0; /* 0% */
+	panel->backlight.max = 100; /* 100% */
+	panel->backlight.level = DIV_ROUND_UP(
+				 pwm_get_duty_cycle(panel->backlight.pwm) * 100,
+				 CRC_PMIC_PWM_PERIOD_NS);
+	panel->backlight.enabled = panel->backlight.level ? true : false;
+
+	return 0;
+}
+
 int intel_panel_setup_backlight(struct drm_connector *connector, enum pipe pipe)
 {
 	struct drm_device *dev = connector->dev;
@@ -1363,11 +1432,19 @@ void intel_panel_init_backlight_funcs(struct drm_device *dev)
 		dev_priv->display.set_backlight = pch_set_backlight;
 		dev_priv->display.get_backlight = pch_get_backlight;
 	} else if (IS_VALLEYVIEW(dev)) {
-		dev_priv->display.setup_backlight = vlv_setup_backlight;
-		dev_priv->display.enable_backlight = vlv_enable_backlight;
-		dev_priv->display.disable_backlight = vlv_disable_backlight;
-		dev_priv->display.set_backlight = vlv_set_backlight;
-		dev_priv->display.get_backlight = vlv_get_backlight;
+		if (dev_priv->vbt.has_mipi) {
+			dev_priv->display.setup_backlight = vlv_setup_mipi_backlight;
+			dev_priv->display.enable_backlight = vlv_enable_mipi_backlight;
+			dev_priv->display.disable_backlight = vlv_disable_mipi_backlight;
+			dev_priv->display.set_backlight = vlv_set_mipi_backlight;
+			dev_priv->display.get_backlight = vlv_get_mipi_backlight;
+		} else {
+			dev_priv->display.setup_backlight = vlv_setup_backlight;
+			dev_priv->display.enable_backlight = vlv_enable_backlight;
+			dev_priv->display.disable_backlight = vlv_disable_backlight;
+			dev_priv->display.set_backlight = vlv_set_backlight;
+			dev_priv->display.get_backlight = vlv_get_backlight;
+		}
 	} else if (IS_GEN4(dev)) {
 		dev_priv->display.setup_backlight = i965_setup_backlight;
 		dev_priv->display.enable_backlight = i965_enable_backlight;
@@ -1404,6 +1481,11 @@ void intel_panel_fini(struct intel_panel *panel)
 	if (panel->downclock_mode)
 		drm_mode_destroy(intel_connector->base.dev,
 				panel->downclock_mode);
+
+	/* dispose of the pwm */
+	if (panel->backlight.pwm)
+		pwm_put(panel->backlight.pwm);
+
 }
 
 void intel_backlight_register(struct drm_device *dev)
-- 
2.1.0

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