[Intel-gfx] [PATCH v4 02/20] drm/i915/icl: Program DSI Escape clock Divider

[Madhav Chauhan]

Escape Clock is used for LP communication across the DSI
Link. To achieve the constant frequency of the escape clock
from the variable DPLL frequency output, a variable divider(M)
is needed. This patch programs the same.

v2: (Jani N) Don't end line with "(".

Signed-off-by: Madhav Chauhan <madhav.chauhan at intel.com>
---
 drivers/gpu/drm/i915/Makefile   |  1 +
 drivers/gpu/drm/i915/i915_reg.h |  1 +
 drivers/gpu/drm/i915/icl_dsi.c  | 64 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/icl_dsi.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 4c6adae..7da5419 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -142,6 +142,7 @@ i915-y += dvo_ch7017.o \
 	  intel_dp_mst.o \
 	  intel_dp.o \
 	  intel_dsi.o \
+	  icl_dsi.o \
 	  intel_dsi_dcs_backlight.o \
 	  intel_dsi_pll.o \
 	  intel_dsi_vbt.o \
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index d414940..414579f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -9536,6 +9536,7 @@ enum skl_power_gate {
 #define  ICL_BYTE_CLK_PER_ESC_CLK_SHIFT	16
 #define  ICL_ESC_CLK_DIV_MASK			0x1ff
 #define  ICL_ESC_CLK_DIV_SHIFT			0
+#define DSI_MAX_ESC_CLK			20000		/* in KHz */
 
 /* Gen4+ Timestamp and Pipe Frame time stamp registers */
 #define GEN4_TIMESTAMP		_MMIO(0x2358)
diff --git a/drivers/gpu/drm/i915/icl_dsi.c b/drivers/gpu/drm/i915/icl_dsi.c
new file mode 100644
index 0000000..a890b36
--- /dev/null
+++ b/drivers/gpu/drm/i915/icl_dsi.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *   Madhav Chauhan <madhav.chauhan at intel.com>
+ *   Jani Nikula <jani.nikula at intel.com>
+ */
+
+#include "intel_dsi.h"
+
+static void gen11_dsi_program_esc_clk_div(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	enum port port;
+	u32 bpp = mipi_dsi_pixel_format_to_bpp(intel_dsi->pixel_format);
+	u32 afe_clk_khz; /* 8X Clock */
+	u32 esc_clk_div_m;
+
+	afe_clk_khz = DIV_ROUND_CLOSEST(intel_dsi->pclk * bpp,
+					intel_dsi->lane_count);
+
+	esc_clk_div_m = DIV_ROUND_UP(afe_clk_khz, DSI_MAX_ESC_CLK);
+
+	for_each_dsi_port(port, intel_dsi->ports) {
+		I915_WRITE(ICL_DSI_ESC_CLK_DIV(port),
+				esc_clk_div_m & ICL_ESC_CLK_DIV_MASK);
+		POSTING_READ(ICL_DSI_ESC_CLK_DIV(port));
+	}
+
+	for_each_dsi_port(port, intel_dsi->ports) {
+		I915_WRITE(ICL_DPHY_ESC_CLK_DIV(port),
+				esc_clk_div_m & ICL_ESC_CLK_DIV_MASK);
+		POSTING_READ(ICL_DPHY_ESC_CLK_DIV(port));
+	}
+}
+
+static void __attribute__((unused))
+gen11_dsi_pre_enable(struct intel_encoder *encoder,
+		const struct intel_crtc_state *pipe_config,
+		const struct drm_connector_state *conn_state)
+{
+	/* step3: enable DSI PLL */
+	gen11_dsi_program_esc_clk_div(encoder);
+}
-- 
2.7.4