drm/i915/bxt: Program Tx Rx and Dphy clocks

BXT DSI clocks are different than previous platforms. So adding a
new function to program following clocks and dividers:
1. Program variable divider to generate input to Tx clock divider
   (Output value must be < 39.5Mhz)
2. Select divide by 2 option to get < 20Mhz for Tx clock
3. Program 8by3 divider to generate Rx clock

v2: Fixed Jani's review comments. Adjusted the Macro definition as
    per convention. Simplified the logic for bit definitions for
    MIPI PORT A and PORT C in same registers.

v3: Refactored the macros for TX, RX Escape and DPHY clocks as per
    Jani's suggestion.

v4: Addressed Jani's review comments.

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

@@ -7547,6 +7547,68 @@ enum skl_disp_power_wells {
 
 #define _MIPI_PORT(port, a, c)	_PORT3(port, a, 0, c)	/* ports A and C only */
 
+/* BXT MIPI clock controls */
+#define BXT_MAX_VAR_OUTPUT_KHZ			39500
+
+#define BXT_MIPI_CLOCK_CTL			0x46090
+#define  BXT_MIPI1_DIV_SHIFT			26
+#define  BXT_MIPI2_DIV_SHIFT			10
+#define  BXT_MIPI_DIV_SHIFT(port)		\
+			_MIPI_PORT(port, BXT_MIPI1_DIV_SHIFT, \
+					BXT_MIPI2_DIV_SHIFT)
+/* Var clock divider to generate TX source. Result must be < 39.5 M */
+#define  BXT_MIPI1_ESCLK_VAR_DIV_MASK		(0x3F << 26)
+#define  BXT_MIPI2_ESCLK_VAR_DIV_MASK		(0x3F << 10)
+#define  BXT_MIPI_ESCLK_VAR_DIV_MASK(port)	\
+			_MIPI_PORT(port, BXT_MIPI1_ESCLK_VAR_DIV_MASK, \
+						BXT_MIPI2_ESCLK_VAR_DIV_MASK)
+
+#define  BXT_MIPI_ESCLK_VAR_DIV(port, val)	\
+			(val << BXT_MIPI_DIV_SHIFT(port))
+/* TX control divider to select actual TX clock output from (8x/var) */
+#define  BXT_MIPI1_TX_ESCLK_SHIFT		21
+#define  BXT_MIPI2_TX_ESCLK_SHIFT		5
+#define  BXT_MIPI_TX_ESCLK_SHIFT(port)		\
+			_MIPI_PORT(port, BXT_MIPI1_TX_ESCLK_SHIFT, \
+					BXT_MIPI2_TX_ESCLK_SHIFT)
+#define  BXT_MIPI1_TX_ESCLK_FIXDIV_MASK		(3 << 21)
+#define  BXT_MIPI2_TX_ESCLK_FIXDIV_MASK		(3 << 5)
+#define  BXT_MIPI_TX_ESCLK_FIXDIV_MASK(port)	\
+			_MIPI_PORT(port, BXT_MIPI1_TX_ESCLK_FIXDIV_MASK, \
+						BXT_MIPI2_TX_ESCLK_FIXDIV_MASK)
+#define  BXT_MIPI_TX_ESCLK_8XDIV_BY2(port)	\
+		(0x0 << BXT_MIPI_TX_ESCLK_SHIFT(port))
+#define  BXT_MIPI_TX_ESCLK_8XDIV_BY4(port)	\
+		(0x1 << BXT_MIPI_TX_ESCLK_SHIFT(port))
+#define  BXT_MIPI_TX_ESCLK_8XDIV_BY8(port)	\
+		(0x2 << BXT_MIPI_TX_ESCLK_SHIFT(port))
+/* RX control divider to select actual RX clock output from 8x*/
+#define  BXT_MIPI1_RX_ESCLK_SHIFT		19
+#define  BXT_MIPI2_RX_ESCLK_SHIFT		3
+#define  BXT_MIPI_RX_ESCLK_SHIFT(port)		\
+			_MIPI_PORT(port, BXT_MIPI1_RX_ESCLK_SHIFT, \
+					BXT_MIPI2_RX_ESCLK_SHIFT)
+#define  BXT_MIPI1_RX_ESCLK_FIXDIV_MASK		(3 << 19)
+#define  BXT_MIPI2_RX_ESCLK_FIXDIV_MASK		(3 << 3)
+#define  BXT_MIPI_RX_ESCLK_FIXDIV_MASK(port)	\
+		(3 << BXT_MIPI_RX_ESCLK_SHIFT(port))
+#define  BXT_MIPI_RX_ESCLK_8X_BY2(port)	\
+		(1 << BXT_MIPI_RX_ESCLK_SHIFT(port))
+#define  BXT_MIPI_RX_ESCLK_8X_BY3(port)	\
+		(2 << BXT_MIPI_RX_ESCLK_SHIFT(port))
+#define  BXT_MIPI_RX_ESCLK_8X_BY4(port)	\
+		(3 << BXT_MIPI_RX_ESCLK_SHIFT(port))
+/* BXT-A WA: Always prog DPHY dividers to 00 */
+#define  BXT_MIPI1_DPHY_DIV_SHIFT		16
+#define  BXT_MIPI2_DPHY_DIV_SHIFT		0
+#define  BXT_MIPI_DPHY_DIV_SHIFT(port)		\
+			_MIPI_PORT(port, BXT_MIPI1_DPHY_DIV_SHIFT, \
+					BXT_MIPI2_DPHY_DIV_SHIFT)
+#define  BXT_MIPI_1_DPHY_DIVIDER_MASK		(3 << 16)
+#define  BXT_MIPI_2_DPHY_DIVIDER_MASK		(3 << 0)
+#define  BXT_MIPI_DPHY_DIVIDER_MASK(port)	\
+		(3 << BXT_MIPI_DPHY_DIV_SHIFT(port))
+
 /* BXT MIPI mode configure */
 #define  _BXT_MIPIA_TRANS_HACTIVE			0x6B0F8
 #define  _BXT_MIPIC_TRANS_HACTIVE			0x6B8F8

drivers/gpu/drm/i915/intel_dsi_pll.c

@@ -384,6 +384,42 @@ u32 vlv_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp)
 	return pclk;
 }
 
+/* Program BXT Mipi clocks and dividers */
+static void bxt_dsi_program_clocks(struct drm_device *dev, enum port port)
+{
+	u32 tmp;
+	u32 divider;
+	u32 dsi_rate;
+	u32 pll_ratio;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	/* Clear old configurations */
+	tmp = I915_READ(BXT_MIPI_CLOCK_CTL);
+	tmp &= ~(BXT_MIPI_TX_ESCLK_FIXDIV_MASK(port));
+	tmp &= ~(BXT_MIPI_RX_ESCLK_FIXDIV_MASK(port));
+	tmp &= ~(BXT_MIPI_ESCLK_VAR_DIV_MASK(port));
+	tmp &= ~(BXT_MIPI_DPHY_DIVIDER_MASK(port));
+
+	/* Get the current DSI rate(actual) */
+	pll_ratio = I915_READ(BXT_DSI_PLL_CTL) &
+				BXT_DSI_PLL_RATIO_MASK;
+	dsi_rate = (BXT_REF_CLOCK_KHZ * pll_ratio) / 2;
+
+	/* Max possible output of clock is 39.5 MHz, program value -1 */
+	divider = (dsi_rate / BXT_MAX_VAR_OUTPUT_KHZ) - 1;
+	tmp |= BXT_MIPI_ESCLK_VAR_DIV(port, divider);
+
+	/*
+	 * Tx escape clock must be as close to 20MHz possible, but should
+	 * not exceed it. Hence select divide by 2
+	 */
+	tmp |= BXT_MIPI_TX_ESCLK_8XDIV_BY2(port);
+
+	tmp |= BXT_MIPI_RX_ESCLK_8X_BY3(port);
+
+	I915_WRITE(BXT_MIPI_CLOCK_CTL, tmp);
+}
+
 static bool bxt_configure_dsi_pll(struct intel_encoder *encoder)
 {
 	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
@@ -435,6 +471,8 @@ static bool bxt_configure_dsi_pll(struct intel_encoder *encoder)
 static void bxt_enable_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);
+	enum port port;
 	u32 val;
 
 	DRM_DEBUG_KMS("\n");
@@ -453,6 +491,10 @@ static void bxt_enable_dsi_pll(struct intel_encoder *encoder)
 		return;
 	}
 
+	/* Program TX, RX, Dphy clocks */
+	for_each_dsi_port(port, intel_dsi->ports)
+		bxt_dsi_program_clocks(encoder->base.dev, port);
+
 	/* Enable DSI PLL */
 	val = I915_READ(BXT_DSI_PLL_ENABLE);
 	val |= BXT_DSI_PLL_DO_ENABLE;