drm/tve200: Add new driver for TVE200

This adds a new DRM driver for the Faraday Technology TVE200
block. This "TV Encoder" encodes a ITU-T BT.656 stream and can
be found in the StorLink SL3516 (later Cortina Systems CS3516)
as well as the Grain Media GM8180.

I do not have definitive word from anyone at Faraday that this
IP block is theirs, but it bears the hallmark of their 3-digit
version code (200) and is used in two SoCs from completely
different companies. (Grain Media was fully owned by Faraday
until it was transferred to NovoTek this january, and
Faraday did lots of work on the StorLink SoCs.)

The D-Link DIR-685 uses this in connection with the Ilitek
ILI9322 panel driver that supports BT.656 input, while the
GM8180 apparently has been used with the Cirrus Logic CS4954
digital video encoder. The oldest user seems to be
something called Techwall 2835.

This driver is heavily inspired by Eric Anholt's PL111
driver and therefore I have mentioned all the ancestor authors
in the header file.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20170820100557.24991-2-linus.walleij@linaro.org

Documentation/gpu/index.rst

@@ -15,6 +15,7 @@ Linux GPU Driver Developer's Guide
    pl111
    tegra
    tinydrm
+   tve200
    vc4
    vga-switcheroo
    vgaarbiter

Documentation/gpu/tve200.rst

@@ -0,0 +1,6 @@
+==================================
+ drm/tve200 Faraday TV Encoder 200
+==================================
+
+.. kernel-doc:: drivers/gpu/drm/tve200/tve200_drv.c
+   :doc: Faraday TV Encoder 200

MAINTAINERS

@@ -4300,6 +4300,12 @@ T:	git git://anongit.freedesktop.org/drm/drm-misc
 S:	Maintained
 F:	drivers/gpu/drm/bochs/
 
+DRM DRIVER FOR FARADAY TVE200 TV ENCODER
+M:	Linus Walleij <linus.walleij@linaro.org>
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+S:	Maintained
+F:	drivers/gpu/drm/tve200/
+
 DRM DRIVER FOR INTEL I810 VIDEO CARDS
 S:	Orphan / Obsolete
 F:	drivers/gpu/drm/i810/

drivers/gpu/drm/Kconfig

@@ -278,6 +278,8 @@ source "drivers/gpu/drm/tinydrm/Kconfig"
 
 source "drivers/gpu/drm/pl111/Kconfig"
 
+source "drivers/gpu/drm/tve200/Kconfig"
+
 # Keep legacy drivers last
 
 menuconfig DRM_LEGACY

drivers/gpu/drm/Makefile

@@ -100,3 +100,4 @@ obj-$(CONFIG_DRM_ZTE)	+= zte/
 obj-$(CONFIG_DRM_MXSFB)	+= mxsfb/
 obj-$(CONFIG_DRM_TINYDRM) += tinydrm/
 obj-$(CONFIG_DRM_PL111) += pl111/
+obj-$(CONFIG_DRM_TVE200) += tve200/

drivers/gpu/drm/tve200/Kconfig

@@ -0,0 +1,15 @@
+config DRM_TVE200
+	tristate "DRM Support for Faraday TV Encoder TVE200"
+	depends on DRM
+	depends on CMA
+	depends on ARM || COMPILE_TEST
+	depends on OF
+	select DRM_PANEL
+	select DRM_KMS_HELPER
+	select DRM_KMS_CMA_HELPER
+	select DRM_GEM_CMA_HELPER
+	select VT_HW_CONSOLE_BINDING if FRAMEBUFFER_CONSOLE
+	help
+	  Choose this option for DRM support for the Faraday TV Encoder
+	  TVE200 Controller.
+	  If M is selected the module will be called tve200_drm.

drivers/gpu/drm/tve200/Makefile

@@ -0,0 +1,5 @@
+tve200_drm-y +=	tve200_connector.o \
+		tve200_display.o \
+		tve200_drv.o
+
+obj-$(CONFIG_DRM_TVE200) += tve200_drm.o

drivers/gpu/drm/tve200/tve200_connector.c

@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
+ * Parts of this file were based on sources as follows:
+ *
+ * Copyright (C) 2006-2008 Intel Corporation
+ * Copyright (C) 2007 Amos Lee <amos_lee@storlinksemi.com>
+ * Copyright (C) 2007 Dave Airlie <airlied@linux.ie>
+ * Copyright (C) 2011 Texas Instruments
+ * Copyright (C) 2017 Eric Anholt
+ *
+ * This program is free software and is provided to you under the terms of the
+ * GNU General Public License version 2 as published by the Free Software
+ * Foundation, and any use by you of this program is subject to the terms of
+ * such GNU licence.
+ */
+
+/**
+ * tve200_drm_connector.c
+ * Implementation of the connector functions for the Faraday TV Encoder
+ */
+#include <linux/version.h>
+#include <linux/shmem_fs.h>
+#include <linux/dma-buf.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+
+#include "tve200_drm.h"
+
+static void tve200_connector_destroy(struct drm_connector *connector)
+{
+	struct tve200_drm_connector *tve200con =
+		to_tve200_connector(connector);
+
+	if (tve200con->panel)
+		drm_panel_detach(tve200con->panel);
+
+	drm_connector_unregister(connector);
+	drm_connector_cleanup(connector);
+}
+
+static enum drm_connector_status tve200_connector_detect(struct drm_connector
+							*connector, bool force)
+{
+	struct tve200_drm_connector *tve200con =
+		to_tve200_connector(connector);
+
+	return (tve200con->panel ?
+		connector_status_connected :
+		connector_status_disconnected);
+}
+
+static int tve200_connector_helper_get_modes(struct drm_connector *connector)
+{
+	struct tve200_drm_connector *tve200con =
+		to_tve200_connector(connector);
+
+	if (!tve200con->panel)
+		return 0;
+
+	return drm_panel_get_modes(tve200con->panel);
+}
+
+static const struct drm_connector_funcs connector_funcs = {
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = tve200_connector_destroy,
+	.detect = tve200_connector_detect,
+	.reset = drm_atomic_helper_connector_reset,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static const struct drm_connector_helper_funcs connector_helper_funcs = {
+	.get_modes = tve200_connector_helper_get_modes,
+};
+
+/*
+ * Walks the OF graph to find the panel node and then asks DRM to look
+ * up the panel.
+ */
+static struct drm_panel *tve200_get_panel(struct device *dev)
+{
+	struct device_node *endpoint, *panel_node;
+	struct device_node *np = dev->of_node;
+	struct drm_panel *panel;
+
+	endpoint = of_graph_get_next_endpoint(np, NULL);
+	if (!endpoint) {
+		dev_err(dev, "no endpoint to fetch panel\n");
+		return NULL;
+	}
+
+	/* Don't proceed if we have an endpoint but no panel_node tied to it */
+	panel_node = of_graph_get_remote_port_parent(endpoint);
+	of_node_put(endpoint);
+	if (!panel_node) {
+		dev_err(dev, "no valid panel node\n");
+		return NULL;
+	}
+
+	panel = of_drm_find_panel(panel_node);
+	of_node_put(panel_node);
+
+	return panel;
+}
+
+int tve200_connector_init(struct drm_device *dev)
+{
+	struct tve200_drm_dev_private *priv = dev->dev_private;
+	struct tve200_drm_connector *tve200con = &priv->connector;
+	struct drm_connector *connector = &tve200con->connector;
+
+	drm_connector_init(dev, connector, &connector_funcs,
+			   DRM_MODE_CONNECTOR_DPI);
+	drm_connector_helper_add(connector, &connector_helper_funcs);
+
+	tve200con->panel = tve200_get_panel(dev->dev);
+	if (tve200con->panel)
+		drm_panel_attach(tve200con->panel, connector);
+
+	return 0;
+}