drm/i915/bxt: Enable BXT DSI PLL

This patch adds new functions for BXT clock and PLL programming.
They are:
1. configure_dsi_pll for BXT.
   This function does the basic math and generates the divider ratio
   based on requested pixclock, and program clock registers.
2. enable_dsi_pll function.
   This function programs the calculated clock values on the PLL.
3. intel_enable_dsi_pll
   Wrapper function to use same code for multiple platforms. It checks the
   platform and calls appropriate core pll enable function.

v2: Fixed Jani's review comments. Macros are adjusted as per convention.

v3: Removed a redundant change wrt code comment.
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -7507,6 +7507,28 @@ enum skl_disp_power_wells {
 
 #define _MIPI_PORT(port, a, c)	_PORT3(port, a, 0, c)	/* ports A and C only */
 
+#define BXT_DSI_PLL_CTL			0x161000
+#define  BXT_DSI_PLL_PVD_RATIO_SHIFT	16
+#define  BXT_DSI_PLL_PVD_RATIO_MASK	(3 << BXT_DSI_PLL_PVD_RATIO_SHIFT)
+#define  BXT_DSI_PLL_PVD_RATIO_1	(1 << BXT_DSI_PLL_PVD_RATIO_SHIFT)
+#define  BXT_DSIC_16X_BY2		(1 << 10)
+#define  BXT_DSIC_16X_BY3		(2 << 10)
+#define  BXT_DSIC_16X_BY4		(3 << 10)
+#define  BXT_DSIA_16X_BY2		(1 << 8)
+#define  BXT_DSIA_16X_BY3		(2 << 8)
+#define  BXT_DSIA_16X_BY4		(3 << 8)
+#define  BXT_DSI_FREQ_SEL_SHIFT		8
+#define  BXT_DSI_FREQ_SEL_MASK		(0xF << BXT_DSI_FREQ_SEL_SHIFT)
+
+#define BXT_DSI_PLL_RATIO_MAX		0x7D
+#define BXT_DSI_PLL_RATIO_MIN		0x22
+#define BXT_DSI_PLL_RATIO_MASK		0xFF
+#define BXT_REF_CLOCK_KHZ		19500
+
+#define BXT_DSI_PLL_ENABLE		0x46080
+#define  BXT_DSI_PLL_DO_ENABLE		(1 << 31)
+#define  BXT_DSI_PLL_LOCKED		(1 << 30)
+
 #define _MIPIA_PORT_CTRL			(VLV_DISPLAY_BASE + 0x61190)
 #define _MIPIC_PORT_CTRL			(VLV_DISPLAY_BASE + 0x61700)
 #define MIPI_PORT_CTRL(port)	_MIPI_PORT(port, _MIPIA_PORT_CTRL, _MIPIC_PORT_CTRL)

drivers/gpu/drm/i915/intel_dsi.c

@@ -914,8 +914,8 @@ static void intel_dsi_pre_pll_enable(struct intel_encoder *encoder)
 	DRM_DEBUG_KMS("\n");
 
 	intel_dsi_prepare(encoder);
+	intel_enable_dsi_pll(encoder);
 
-	vlv_enable_dsi_pll(encoder);
 }
 
 static enum drm_connector_status

drivers/gpu/drm/i915/intel_dsi.h

@@ -124,7 +124,7 @@ static inline struct intel_dsi *enc_to_intel_dsi(struct drm_encoder *encoder)
 	return container_of(encoder, struct intel_dsi, base.base);
 }
 
-extern void vlv_enable_dsi_pll(struct intel_encoder *encoder);
+extern void intel_enable_dsi_pll(struct intel_encoder *encoder);
 extern void vlv_disable_dsi_pll(struct intel_encoder *encoder);
 extern u32 vlv_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp);
 

drivers/gpu/drm/i915/intel_dsi_pll.c

@@ -246,7 +246,7 @@ static void vlv_configure_dsi_pll(struct intel_encoder *encoder)
 	vlv_cck_write(dev_priv, CCK_REG_DSI_PLL_CONTROL, dsi_mnp.dsi_pll_ctrl);
 }
 
-void vlv_enable_dsi_pll(struct intel_encoder *encoder)
+static void vlv_enable_dsi_pll(struct intel_encoder *encoder)
 {
 	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
 	u32 tmp;
@@ -363,3 +363,96 @@ u32 vlv_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp)
 
 	return pclk;
 }
+
+static bool bxt_configure_dsi_pll(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
+	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	u8 dsi_ratio;
+	u32 dsi_clk;
+	u32 val;
+
+	dsi_clk = dsi_clk_from_pclk(intel_dsi->pclk, intel_dsi->pixel_format,
+			intel_dsi->lane_count);
+
+	/*
+	 * From clock diagram, to get PLL ratio divider, divide double of DSI
+	 * link rate (i.e., 2*8x=16x frequency value) by ref clock. Make sure to
+	 * round 'up' the result
+	 */
+	dsi_ratio = DIV_ROUND_UP(dsi_clk * 2, BXT_REF_CLOCK_KHZ);
+	if (dsi_ratio < BXT_DSI_PLL_RATIO_MIN ||
+			dsi_ratio > BXT_DSI_PLL_RATIO_MAX) {
+		DRM_ERROR("Cant get a suitable ratio from DSI PLL ratios\n");
+		return false;
+	}
+
+	/*
+	 * Program DSI ratio and Select MIPIC and MIPIA PLL output as 8x
+	 * Spec says both have to be programmed, even if one is not getting
+	 * used. Configure MIPI_CLOCK_CTL dividers in modeset
+	 */
+	val = I915_READ(BXT_DSI_PLL_CTL);
+	val &= ~BXT_DSI_PLL_PVD_RATIO_MASK;
+	val &= ~BXT_DSI_FREQ_SEL_MASK;
+	val &= ~BXT_DSI_PLL_RATIO_MASK;
+	val |= (dsi_ratio | BXT_DSIA_16X_BY2 | BXT_DSIC_16X_BY2);
+
+	/* As per recommendation from hardware team,
+	 * Prog PVD ratio =1 if dsi ratio <= 50
+	 */
+	if (dsi_ratio <= 50) {
+		val &= ~BXT_DSI_PLL_PVD_RATIO_MASK;
+		val |= BXT_DSI_PLL_PVD_RATIO_1;
+	}
+
+	I915_WRITE(BXT_DSI_PLL_CTL, val);
+	POSTING_READ(BXT_DSI_PLL_CTL);
+
+	return true;
+}
+
+static void bxt_enable_dsi_pll(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
+	u32 val;
+
+	DRM_DEBUG_KMS("\n");
+
+	val = I915_READ(BXT_DSI_PLL_ENABLE);
+
+	if (val & BXT_DSI_PLL_DO_ENABLE) {
+		WARN(1, "DSI PLL already enabled. Disabling it.\n");
+		val &= ~BXT_DSI_PLL_DO_ENABLE;
+		I915_WRITE(BXT_DSI_PLL_ENABLE, val);
+	}
+
+	/* Configure PLL vales */
+	if (!bxt_configure_dsi_pll(encoder)) {
+		DRM_ERROR("Configure DSI PLL failed, abort PLL enable\n");
+		return;
+	}
+
+	/* Enable DSI PLL */
+	val = I915_READ(BXT_DSI_PLL_ENABLE);
+	val |= BXT_DSI_PLL_DO_ENABLE;
+	I915_WRITE(BXT_DSI_PLL_ENABLE, val);
+
+	/* Timeout and fail if PLL not locked */
+	if (wait_for(I915_READ(BXT_DSI_PLL_ENABLE) & BXT_DSI_PLL_LOCKED, 1)) {
+		DRM_ERROR("Timed out waiting for DSI PLL to lock\n");
+		return;
+	}
+
+	DRM_DEBUG_KMS("DSI PLL locked\n");
+}
+
+void intel_enable_dsi_pll(struct intel_encoder *encoder)
+{
+	struct drm_device *dev = encoder->base.dev;
+
+	if (IS_VALLEYVIEW(dev))
+		vlv_enable_dsi_pll(encoder);
+	else if (IS_BROXTON(dev))
+		bxt_enable_dsi_pll(encoder);
+}