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From:   Liu Ying <victor.liu@nxp.com>
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        jernej.skrabec@siol.net, kishon@ti.com, vkoul@kernel.org,
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Subject: [PATCH v6 06/14] drm/bridge: imx: Add i.MX8qm/qxp display pixel link support
Date:   Wed, 17 Mar 2021 11:42:41 +0800
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This patch adds a drm bridge driver for i.MX8qm/qxp display pixel link.
The pixel link forms a standard asynchronous linkage between
pixel sources(display controller or camera module) and pixel
consumers(imaging or displays).  It consists of two distinct
functions, a pixel transfer function and a control interface.

Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Liu Ying <victor.liu@nxp.com>
---
v5->v6:
* No change.

v4->v5:
* Make a comment occupy a line. (Robert)
* Add Robert's R-b tag.

v3->v4:
* No change.

v2->v3:
* Drop two macros which help define functions and define them directly.
* Properly disable all pixel link controls to POR value by calling
  imx8qxp_pixel_link_disable_all_controls() from
  imx8qxp_pixel_link_bridge_probe().

v1->v2:
* Rewrite the function to find the next bridge by properly using OF APIs
  and dropping unnecessary DT validation. (Rob)

 drivers/gpu/drm/bridge/imx/Kconfig              |   8 +
 drivers/gpu/drm/bridge/imx/Makefile             |   1 +
 drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c | 427 ++++++++++++++++++++++++
 3 files changed, 436 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c

diff --git a/drivers/gpu/drm/bridge/imx/Kconfig b/drivers/gpu/drm/bridge/imx/Kconfig
index f1c91b6..4d1f027 100644
--- a/drivers/gpu/drm/bridge/imx/Kconfig
+++ b/drivers/gpu/drm/bridge/imx/Kconfig
@@ -6,3 +6,11 @@ config DRM_IMX8QXP_PIXEL_COMBINER
 	help
 	  Choose this to enable pixel combiner found in
 	  Freescale i.MX8qm/qxp processors.
+
+config DRM_IMX8QXP_PIXEL_LINK
+	tristate "Freescale i.MX8QM/QXP display pixel link"
+	depends on OF
+	select DRM_KMS_HELPER
+	help
+	  Choose this to enable display pixel link found in
+	  Freescale i.MX8qm/qxp processors.
diff --git a/drivers/gpu/drm/bridge/imx/Makefile b/drivers/gpu/drm/bridge/imx/Makefile
index 7d7c8d6..c15469f 100644
--- a/drivers/gpu/drm/bridge/imx/Makefile
+++ b/drivers/gpu/drm/bridge/imx/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_DRM_IMX8QXP_PIXEL_COMBINER) += imx8qxp-pixel-combiner.o
+obj-$(CONFIG_DRM_IMX8QXP_PIXEL_LINK) += imx8qxp-pixel-link.o
diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
new file mode 100644
index 00000000..a549624
--- /dev/null
+++ b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c
@@ -0,0 +1,427 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Copyright 2020 NXP
+ */
+
+#include <linux/firmware/imx/svc/misc.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_graph.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_print.h>
+
+#include <dt-bindings/firmware/imx/rsrc.h>
+
+#define DRIVER_NAME		"imx8qxp-display-pixel-link"
+#define PL_MAX_MST_ADDR		3
+#define PL_MAX_NEXT_BRIDGES	2
+
+struct imx8qxp_pixel_link {
+	struct drm_bridge bridge;
+	struct drm_bridge *next_bridge;
+	struct device *dev;
+	struct imx_sc_ipc *ipc_handle;
+	int id;
+	int stream_id;
+	int dc_id;
+	u32 sink_rsc;
+	u32 mst_addr;
+	u8 mst_addr_ctrl;
+	u8 mst_en_ctrl;
+	u8 mst_vld_ctrl;
+	u8 sync_ctrl;
+};
+
+static void imx8qxp_pixel_link_enable_mst_en(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
+				      pl->mst_en_ctrl, true);
+	if (ret)
+		DRM_DEV_ERROR(pl->dev,
+			"failed to enable DC%d stream%d pixel link mst_en: %d\n",
+						pl->dc_id, pl->stream_id, ret);
+}
+
+static void imx8qxp_pixel_link_enable_mst_vld(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
+				      pl->mst_vld_ctrl, true);
+	if (ret)
+		DRM_DEV_ERROR(pl->dev,
+		"failed to enable DC%d stream%d pixel link mst_vld: %d\n",
+						pl->dc_id, pl->stream_id, ret);
+}
+
+static void imx8qxp_pixel_link_enable_sync(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
+				      pl->sync_ctrl, true);
+	if (ret)
+		DRM_DEV_ERROR(pl->dev,
+			"failed to enable DC%d stream%d pixel link sync: %d\n",
+						pl->dc_id, pl->stream_id, ret);
+}
+
+static int imx8qxp_pixel_link_disable_mst_en(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
+				      pl->mst_en_ctrl, false);
+	if (ret)
+		DRM_DEV_ERROR(pl->dev,
+		"failed to disable DC%d stream%d pixel link mst_en: %d\n",
+						pl->dc_id, pl->stream_id, ret);
+
+	return ret;
+}
+
+static int imx8qxp_pixel_link_disable_mst_vld(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
+				      pl->mst_vld_ctrl, false);
+	if (ret)
+		DRM_DEV_ERROR(pl->dev,
+		"failed to disable DC%d stream%d pixel link mst_vld: %d\n",
+						pl->dc_id, pl->stream_id, ret);
+
+	return ret;
+}
+
+static int imx8qxp_pixel_link_disable_sync(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx_sc_misc_set_control(pl->ipc_handle, pl->sink_rsc,
+				      pl->sync_ctrl, false);
+	if (ret)
+		DRM_DEV_ERROR(pl->dev,
+			"failed to disable DC%d stream%d pixel link sync: %d\n",
+						pl->dc_id, pl->stream_id, ret);
+
+	return ret;
+}
+
+static void imx8qxp_pixel_link_set_mst_addr(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx_sc_misc_set_control(pl->ipc_handle,
+				      pl->sink_rsc, pl->mst_addr_ctrl,
+				      pl->mst_addr);
+	if (ret)
+		DRM_DEV_ERROR(pl->dev,
+		    "failed to set DC%d stream%d pixel link mst addr(%u): %d\n",
+		    pl->dc_id, pl->stream_id, pl->mst_addr, ret);
+}
+
+static int imx8qxp_pixel_link_bridge_attach(struct drm_bridge *bridge,
+					    enum drm_bridge_attach_flags flags)
+{
+	struct imx8qxp_pixel_link *pl = bridge->driver_private;
+
+	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
+		DRM_DEV_ERROR(pl->dev,
+			      "do not support creating a drm_connector\n");
+		return -EINVAL;
+	}
+
+	if (!bridge->encoder) {
+		DRM_DEV_ERROR(pl->dev, "missing encoder\n");
+		return -ENODEV;
+	}
+
+	return drm_bridge_attach(bridge->encoder,
+				 pl->next_bridge, bridge,
+				 DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+}
+
+static void
+imx8qxp_pixel_link_bridge_mode_set(struct drm_bridge *bridge,
+				   const struct drm_display_mode *mode,
+				   const struct drm_display_mode *adjusted_mode)
+{
+	struct imx8qxp_pixel_link *pl = bridge->driver_private;
+
+	imx8qxp_pixel_link_set_mst_addr(pl);
+}
+
+static void imx8qxp_pixel_link_bridge_atomic_enable(struct drm_bridge *bridge,
+			      struct drm_bridge_state *old_bridge_state)
+{
+	struct imx8qxp_pixel_link *pl = bridge->driver_private;
+
+	imx8qxp_pixel_link_enable_mst_en(pl);
+	imx8qxp_pixel_link_enable_mst_vld(pl);
+	imx8qxp_pixel_link_enable_sync(pl);
+}
+
+static void imx8qxp_pixel_link_bridge_atomic_disable(struct drm_bridge *bridge,
+				struct drm_bridge_state *old_bridge_state)
+{
+	struct imx8qxp_pixel_link *pl = bridge->driver_private;
+
+	imx8qxp_pixel_link_disable_mst_en(pl);
+	imx8qxp_pixel_link_disable_mst_vld(pl);
+	imx8qxp_pixel_link_disable_sync(pl);
+}
+
+static const u32 imx8qxp_pixel_link_bus_output_fmts[] = {
+	MEDIA_BUS_FMT_RGB888_1X36_CPADLO,
+	MEDIA_BUS_FMT_RGB666_1X36_CPADLO,
+};
+
+static bool imx8qxp_pixel_link_bus_output_fmt_supported(u32 fmt)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(imx8qxp_pixel_link_bus_output_fmts); i++) {
+		if (imx8qxp_pixel_link_bus_output_fmts[i] == fmt)
+			return true;
+	}
+
+	return false;
+}
+
+static u32 *
+imx8qxp_pixel_link_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
+					struct drm_bridge_state *bridge_state,
+					struct drm_crtc_state *crtc_state,
+					struct drm_connector_state *conn_state,
+					u32 output_fmt,
+					unsigned int *num_input_fmts)
+{
+	u32 *input_fmts;
+
+	if (!imx8qxp_pixel_link_bus_output_fmt_supported(output_fmt))
+		return NULL;
+
+	*num_input_fmts = 1;
+
+	input_fmts = kmalloc(sizeof(*input_fmts), GFP_KERNEL);
+	if (!input_fmts)
+		return NULL;
+
+	input_fmts[0] = output_fmt;
+
+	return input_fmts;
+}
+
+static u32 *
+imx8qxp_pixel_link_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
+					struct drm_bridge_state *bridge_state,
+					struct drm_crtc_state *crtc_state,
+					struct drm_connector_state *conn_state,
+					unsigned int *num_output_fmts)
+{
+	*num_output_fmts = ARRAY_SIZE(imx8qxp_pixel_link_bus_output_fmts);
+	return kmemdup(imx8qxp_pixel_link_bus_output_fmts,
+			sizeof(imx8qxp_pixel_link_bus_output_fmts), GFP_KERNEL);
+}
+
+static const struct drm_bridge_funcs imx8qxp_pixel_link_bridge_funcs = {
+	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
+	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
+	.atomic_reset		= drm_atomic_helper_bridge_reset,
+	.attach			= imx8qxp_pixel_link_bridge_attach,
+	.mode_set		= imx8qxp_pixel_link_bridge_mode_set,
+	.atomic_enable		= imx8qxp_pixel_link_bridge_atomic_enable,
+	.atomic_disable		= imx8qxp_pixel_link_bridge_atomic_disable,
+	.atomic_get_input_bus_fmts =
+			imx8qxp_pixel_link_bridge_atomic_get_input_bus_fmts,
+	.atomic_get_output_bus_fmts =
+			imx8qxp_pixel_link_bridge_atomic_get_output_bus_fmts,
+};
+
+static int imx8qxp_pixel_link_disable_all_controls(struct imx8qxp_pixel_link *pl)
+{
+	int ret;
+
+	ret = imx8qxp_pixel_link_disable_mst_en(pl);
+	if (ret)
+		return ret;
+
+	ret = imx8qxp_pixel_link_disable_mst_vld(pl);
+	if (ret)
+		return ret;
+
+	return imx8qxp_pixel_link_disable_sync(pl);
+}
+
+static struct drm_bridge *
+imx8qxp_pixel_link_find_next_bridge(struct imx8qxp_pixel_link *pl)
+{
+	struct device_node *np = pl->dev->of_node;
+	struct device_node *port, *remote;
+	struct drm_bridge *next_bridge[PL_MAX_NEXT_BRIDGES];
+	u32 port_id;
+	bool found_port = false;
+	int reg, ep_cnt = 0;
+	/* select the first next bridge by default */
+	int bridge_sel = 0;
+
+	for (port_id = 1; port_id <= PL_MAX_MST_ADDR + 1; port_id++) {
+		port = of_graph_get_port_by_id(np, port_id);
+		if (!port)
+			continue;
+
+		if (of_device_is_available(port)) {
+			found_port = true;
+			of_node_put(port);
+			break;
+		}
+
+		of_node_put(port);
+	}
+
+	if (!found_port) {
+		DRM_DEV_ERROR(pl->dev, "no available output port\n");
+		return ERR_PTR(-ENODEV);
+	}
+
+	for (reg = 0; reg < PL_MAX_NEXT_BRIDGES; reg++) {
+		remote = of_graph_get_remote_node(np, port_id, reg);
+		if (!remote)
+			continue;
+
+		if (!of_device_is_available(remote->parent)) {
+			DRM_DEV_DEBUG(pl->dev,
+			   "port%u endpoint%u remote parent is not available\n",
+								port_id, reg);
+			of_node_put(remote);
+			continue;
+		}
+
+		next_bridge[ep_cnt] = of_drm_find_bridge(remote);
+		if (!next_bridge[ep_cnt]) {
+			of_node_put(remote);
+			return ERR_PTR(-EPROBE_DEFER);
+		}
+
+		/* specially select the next bridge with companion PXL2DPI */
+		if (of_find_property(remote, "fsl,companion-pxl2dpi", NULL))
+			bridge_sel = ep_cnt;
+
+		ep_cnt++;
+
+		of_node_put(remote);
+	}
+
+	pl->mst_addr = port_id - 1;
+
+	return next_bridge[bridge_sel];
+}
+
+static int imx8qxp_pixel_link_bridge_probe(struct platform_device *pdev)
+{
+	struct imx8qxp_pixel_link *pl;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	int ret;
+
+	pl = devm_kzalloc(dev, sizeof(*pl), GFP_KERNEL);
+	if (!pl)
+		return -ENOMEM;
+
+	ret = imx_scu_get_handle(&pl->ipc_handle);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			DRM_DEV_ERROR(dev, "failed to get SCU ipc handle: %d\n",
+									ret);
+		return ret;
+	}
+
+	pl->id = of_alias_get_id(np, "dc_pl");
+	if (pl->id < 0) {
+		DRM_DEV_ERROR(dev,
+			      "failed to get pixel link node alias id: %d\n",
+								pl->id);
+		return pl->id;
+	}
+
+	pl->dev = dev;
+
+	pl->dc_id = pl->id / 2;
+	pl->stream_id = pl->id % 2;
+
+	pl->sink_rsc = pl->dc_id ? IMX_SC_R_DC_1 : IMX_SC_R_DC_0;
+
+	if (pl->stream_id == 0) {
+		pl->mst_addr_ctrl = IMX_SC_C_PXL_LINK_MST1_ADDR;
+		pl->mst_en_ctrl   = IMX_SC_C_PXL_LINK_MST1_ENB;
+		pl->mst_vld_ctrl  = IMX_SC_C_PXL_LINK_MST1_VLD;
+		pl->sync_ctrl     = IMX_SC_C_SYNC_CTRL0;
+	} else {
+		pl->mst_addr_ctrl = IMX_SC_C_PXL_LINK_MST2_ADDR;
+		pl->mst_en_ctrl   = IMX_SC_C_PXL_LINK_MST2_ENB;
+		pl->mst_vld_ctrl  = IMX_SC_C_PXL_LINK_MST2_VLD;
+		pl->sync_ctrl     = IMX_SC_C_SYNC_CTRL1;
+	}
+
+	/* disable all controls to POR default */
+	ret = imx8qxp_pixel_link_disable_all_controls(pl);
+	if (ret)
+		return ret;
+
+	pl->next_bridge = imx8qxp_pixel_link_find_next_bridge(pl);
+	if (IS_ERR(pl->next_bridge)) {
+		ret = PTR_ERR(pl->next_bridge);
+		if (ret != -EPROBE_DEFER)
+			DRM_DEV_ERROR(dev, "failed to find next bridge: %d\n",
+									ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, pl);
+
+	pl->bridge.driver_private = pl;
+	pl->bridge.funcs = &imx8qxp_pixel_link_bridge_funcs;
+	pl->bridge.of_node = np;
+
+	drm_bridge_add(&pl->bridge);
+
+	return ret;
+}
+
+static int imx8qxp_pixel_link_bridge_remove(struct platform_device *pdev)
+{
+	struct imx8qxp_pixel_link *pl = platform_get_drvdata(pdev);
+
+	drm_bridge_remove(&pl->bridge);
+
+	return 0;
+}
+
+static const struct of_device_id imx8qxp_pixel_link_dt_ids[] = {
+	{ .compatible = "fsl,imx8qm-dc-pixel-link", },
+	{ .compatible = "fsl,imx8qxp-dc-pixel-link", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx8qxp_pixel_link_dt_ids);
+
+static struct platform_driver imx8qxp_pixel_link_bridge_driver = {
+	.probe	= imx8qxp_pixel_link_bridge_probe,
+	.remove = imx8qxp_pixel_link_bridge_remove,
+	.driver	= {
+		.of_match_table = imx8qxp_pixel_link_dt_ids,
+		.name = DRIVER_NAME,
+	},
+};
+module_platform_driver(imx8qxp_pixel_link_bridge_driver);
+
+MODULE_DESCRIPTION("i.MX8QXP/QM display pixel link bridge driver");
+MODULE_AUTHOR("Liu Ying <victor.liu@nxp.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRIVER_NAME);
-- 
2.7.4