drm/i915: Backlight control using CRC PMIC based PWM driver

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

v2: Modify to use pwm_config callback
v3: Addressed Jani's comments
    - Renamed all function as pwm_* instead of vlv_*
    - Call intel_panel_actually_set_backlight in enable function
    - Return -ENODEV in case pwm_get fails
    - in case pwm_config error return error cdoe from pwm_config
    - Cleanup pwm in intel_panel_destroy_backlight
v4: Removed unused #defines and initialized backlight with INVALID_PIPE (Ville)

CC: Samuel Ortiz <sameo@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_drv.h

@@ -182,6 +182,10 @@ 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;
 

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 +1136,7 @@ void intel_dsi_init(struct drm_device *dev)
 	}
 
 	intel_panel_init(&intel_connector->panel, fixed_mode, NULL);
+	intel_panel_setup_backlight(connector, INVALID_PIPE);
 
 	return;
 

drivers/gpu/drm/i915/intel_panel.c

@@ -32,8 +32,11 @@
 
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
+#include <linux/pwm.h>
 #include "intel_drv.h"
 
+#define CRC_PMIC_PWM_PERIOD_NS	21333
+
 void
 intel_fixed_panel_mode(const struct drm_display_mode *fixed_mode,
 		       struct drm_display_mode *adjusted_mode)
@@ -544,6 +547,15 @@ static u32 bxt_get_backlight(struct intel_connector *connector)
 	return I915_READ(BXT_BLC_PWM_DUTY1);
 }
 
+static u32 pwm_get_backlight(struct intel_connector *connector)
+{
+	struct intel_panel *panel = &connector->panel;
+	int duty_ns;
+
+	duty_ns = pwm_get_duty_cycle(panel->backlight.pwm);
+	return DIV_ROUND_UP(duty_ns * 100, CRC_PMIC_PWM_PERIOD_NS);
+}
+
 static u32 intel_panel_get_backlight(struct intel_connector *connector)
 {
 	struct drm_device *dev = connector->base.dev;
@@ -632,6 +644,14 @@ static void bxt_set_backlight(struct intel_connector *connector, u32 level)
 	I915_WRITE(BXT_BLC_PWM_DUTY1, level);
 }
 
+static void pwm_set_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)
 {
@@ -769,6 +789,16 @@ static void bxt_disable_backlight(struct intel_connector *connector)
 	I915_WRITE(BXT_BLC_PWM_CTL1, tmp & ~BXT_BLC_PWM_ENABLE);
 }
 
+static void pwm_disable_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;
@@ -1010,6 +1040,14 @@ static void bxt_enable_backlight(struct intel_connector *connector)
 	I915_WRITE(BXT_BLC_PWM_CTL1, pwm_ctl | BXT_BLC_PWM_ENABLE);
 }
 
+static void pwm_enable_backlight(struct intel_connector *connector)
+{
+	struct intel_panel *panel = &connector->panel;
+
+	pwm_enable(panel->backlight.pwm);
+	intel_panel_actually_set_backlight(connector, panel->backlight.level);
+}
+
 void intel_panel_enable_backlight(struct intel_connector *connector)
 {
 	struct drm_device *dev = connector->base.dev;
@@ -1386,6 +1424,40 @@ bxt_setup_backlight(struct intel_connector *connector, enum pipe unused)
 	return 0;
 }
 
+static int pwm_setup_backlight(struct intel_connector *connector,
+			       enum pipe pipe)
+{
+	struct drm_device *dev = connector->base.dev;
+	struct intel_panel *panel = &connector->panel;
+	int retval;
+
+	/* Get the PWM chip for backlight control */
+	panel->backlight.pwm = pwm_get(dev->dev, "pwm_backlight");
+	if (IS_ERR(panel->backlight.pwm)) {
+		DRM_ERROR("Failed to own the pwm chip\n");
+		panel->backlight.pwm = NULL;
+		return -ENODEV;
+	}
+
+	retval = pwm_config(panel->backlight.pwm, CRC_PMIC_PWM_PERIOD_NS,
+			    CRC_PMIC_PWM_PERIOD_NS);
+	if (retval < 0) {
+		DRM_ERROR("Failed to configure the pwm chip\n");
+		pwm_put(panel->backlight.pwm);
+		panel->backlight.pwm = NULL;
+		return retval;
+	}
+
+	panel->backlight.min = 0; /* 0% */
+	panel->backlight.max = 100; /* 100% */
+	panel->backlight.level = DIV_ROUND_UP(
+				 pwm_get_duty_cycle(panel->backlight.pwm) * 100,
+				 CRC_PMIC_PWM_PERIOD_NS);
+	panel->backlight.enabled = panel->backlight.level != 0;
+
+	return 0;
+}
+
 int intel_panel_setup_backlight(struct drm_connector *connector, enum pipe pipe)
 {
 	struct drm_device *dev = connector->dev;
@@ -1429,6 +1501,10 @@ void intel_panel_destroy_backlight(struct drm_connector *connector)
 	struct intel_connector *intel_connector = to_intel_connector(connector);
 	struct intel_panel *panel = &intel_connector->panel;
 
+	/* dispose of the pwm */
+	if (panel->backlight.pwm)
+		pwm_put(panel->backlight.pwm);
+
 	panel->backlight.present = false;
 }
 
@@ -1456,11 +1532,19 @@ 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)) {
+		if (dev_priv->vbt.has_mipi) {
+			dev_priv->display.setup_backlight = pwm_setup_backlight;
+			dev_priv->display.enable_backlight = pwm_enable_backlight;
+			dev_priv->display.disable_backlight = pwm_disable_backlight;
+			dev_priv->display.set_backlight = pwm_set_backlight;
+			dev_priv->display.get_backlight = pwm_get_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;