[Intel-gfx] [RFC PATCH 1/3] drm/i915: add opregion function to notify BIOS of CDCLK changes

[Jani Nikula]

Notifying the BIOS about CDCLK changes lets it program audio controller
EM4/EM5 divider values accordingly.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h       |  6 ++++++
 drivers/gpu/drm/i915/intel_opregion.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8cea59649ef2..2feb8215f9fa 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2602,6 +2602,7 @@ extern int intel_opregion_notify_encoder(struct intel_encoder *intel_encoder,
 					 bool enable);
 extern int intel_opregion_notify_adapter(struct drm_device *dev,
 					 pci_power_t state);
+extern int intel_opregion_notify_cdclk(struct drm_device *dev, int cdclk);
 #else
 static inline int intel_opregion_setup(struct drm_device *dev) { return 0; }
 static inline void intel_opregion_init(struct drm_device *dev) { return; }
@@ -2617,6 +2618,11 @@ intel_opregion_notify_adapter(struct drm_device *dev, pci_power_t state)
 {
 	return 0;
 }
+static inline int
+intel_opregion_notify_cdclk(struct drm_device *dev, int cdclk)
+{
+	return 0;
+}
 #endif
 
 /* intel_acpi.c */
diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
index 2e2c71fcc9ed..6450d2625624 100644
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -219,6 +219,7 @@ struct opregion_asle {
 #define SWSCI_SBCB_SET_SPREAD_SPECTRUM	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 18)
 #define SWSCI_SBCB_POST_VBE_PM		SWSCI_FUNCTION_CODE(SWSCI_SBCB, 19)
 #define SWSCI_SBCB_ENABLE_DISABLE_AUDIO	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 21)
+#define SWSCI_SBCB_CD_CLOCK_CHANGE	SWSCI_FUNCTION_CODE(SWSCI_SBCB, 22)
 
 #define ACPI_OTHER_OUTPUT (0<<8)
 #define ACPI_VGA_OUTPUT (1<<8)
@@ -395,6 +396,34 @@ int intel_opregion_notify_adapter(struct drm_device *dev, pci_power_t state)
 	return -EINVAL;
 }
 
+int intel_opregion_notify_cdclk(struct drm_device *dev, int cdclk)
+{
+	u32 parm;
+
+	if (!IS_BROADWELL(dev))
+		return 0;
+
+	switch (cdclk) {
+	case 337500:
+		parm = 2;
+		break;
+	case 450000:
+		parm = 0;
+		break;
+	case 540000:
+		parm = 1;
+		break;
+	case 675000:
+		parm = 3;
+		break;
+	default:
+		WARN_ONCE(1, "unknown cdclk %d\n", cdclk);
+		return -EINVAL;
+	}
+
+	return swsci(dev, SWSCI_SBCB_CD_CLOCK_CHANGE, parm, NULL);
+}
+
 static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-- 
2.0.0