[Intel-gfx] [RFC v5 9/9] drm/i915: Backlight control using CRC PMIC based PWM driver

[Shobhit Kumar]

CC: Samuel Ortiz <sameo at linux.intel.com>
Cc: Linus Walleij <linus.walleij at linaro.org>
Cc: Alexandre Courbot <gnurou at gmail.com>
Cc: Thierry Reding <thierry.reding at gmail.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar at intel.com>
---
 drivers/gpu/drm/i915/intel_dsi.c | 25 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_dsi.h |  3 +++
 2 files changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index 219421c..511446f 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -32,6 +32,7 @@
 #include <drm/drm_mipi_dsi.h>
 #include <linux/slab.h>
 #include <linux/gpio/consumer.h>
+#include <linux/pwm.h>
 #include "i915_drv.h"
 #include "intel_drv.h"
 #include "intel_dsi.h"
@@ -402,6 +403,10 @@ static void intel_dsi_enable(struct intel_encoder *encoder)
 
 		intel_dsi_port_enable(encoder);
 	}
+
+	/* Enable the backlight with default PWM as programmed by BIOS */
+	pwm_enable(intel_dsi->pwm);
+	pwm_config_alternate(intel_dsi->pwm, 0x7F, 100);
 }
 
 static void intel_dsi_pre_enable(struct intel_encoder *encoder)
@@ -467,6 +472,11 @@ static void intel_dsi_pre_disable(struct intel_encoder *encoder)
 
 	DRM_DEBUG_KMS("\n");
 
+	/* Disable the backlight */
+	pwm_config_alternate(intel_dsi->pwm, 0x7F, 0);
+	usleep_range(2000, 3000);
+	pwm_disable(intel_dsi->pwm);
+
 	if (is_vid_mode(intel_dsi)) {
 		/* Send Shutdown command to the panel in LP mode */
 		for_each_dsi_port(port, intel_dsi->ports)
@@ -971,6 +981,10 @@ static void intel_dsi_encoder_destroy(struct drm_encoder *encoder)
 	if (intel_dsi->gpio_panel)
 		gpiod_put(intel_dsi->gpio_panel);
 
+	/* dispose of the pwm */
+	if (intel_dsi->pwm)
+		pwm_put(intel_dsi->pwm);
+
 	intel_encoder_destroy(encoder);
 }
 
@@ -1098,6 +1112,17 @@ void intel_dsi_init(struct drm_device *dev)
 			DRM_ERROR("Failed to own gpio for panel control\n");
 			intel_dsi->gpio_panel = NULL;
 		}
+
+		/* Get the PWM chip for backlight control */
+		intel_dsi->pwm = pwm_get(dev->dev, "pwm_backlight");
+		if (IS_ERR(intel_dsi->pwm)) {
+			DRM_ERROR("Faild to own the pwm chip\n");
+			intel_dsi->pwm = NULL;
+		} else if (pwm_config_alternate(intel_dsi->pwm, 0x7F, 100) < 0) {
+			DRM_ERROR("Failed to configure the pwm chip\n");
+			pwm_put(intel_dsi->pwm);
+			intel_dsi->pwm = NULL;
+		}
 	}
 
 	intel_encoder->type = INTEL_OUTPUT_DSI;
diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
index 8be75a7..d8ec9c1 100644
--- a/drivers/gpu/drm/i915/intel_dsi.h
+++ b/drivers/gpu/drm/i915/intel_dsi.h
@@ -52,6 +52,9 @@ struct intel_dsi {
 	/* GPIO Desc for CRC based Panel control */
 	struct gpio_desc *gpio_panel;
 
+	/* PWM chip */
+	struct pwm_device *pwm;
+
 	struct intel_connector *attached_connector;
 
 	/* bit mask of ports being driven */
-- 
2.1.0