drm/bridge: dumb-vga-dac: Rename driver to simple-bridge

The dumb-vga-dac driver can support simple DRM bridges without being
limited to VGA DACs. Rename it to simple-bridge.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-12-laurent.pinchart@ideasonboard.com

1 files changed, 306 insertions, 0 deletions

diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c
new file mode 100644
index 000000000000..00d810c99193
--- /dev/null
+++ b/drivers/gpu/drm/bridge/simple-bridge.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015-2016 Free Electrons
+ * Copyright (C) 2015-2016 NextThing Co
+ *
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ */
+
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_graph.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+
+struct simple_bridge {
+	struct drm_bridge	bridge;
+	struct drm_connector	connector;
+
+	struct i2c_adapter	*ddc;
+	struct regulator	*vdd;
+};
+
+static inline struct simple_bridge *
+drm_bridge_to_simple_bridge(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct simple_bridge, bridge);
+}
+
+static inline struct simple_bridge *
+drm_connector_to_simple_bridge(struct drm_connector *connector)
+{
+	return container_of(connector, struct simple_bridge, connector);
+}
+
+static int simple_bridge_get_modes(struct drm_connector *connector)
+{
+	struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
+	struct edid *edid;
+	int ret;
+
+	if (!sbridge->ddc)
+		goto fallback;
+
+	edid = drm_get_edid(connector, sbridge->ddc);
+	if (!edid) {
+		DRM_INFO("EDID readout failed, falling back to standard modes\n");
+		goto fallback;
+	}
+
+	drm_connector_update_edid_property(connector, edid);
+	ret = drm_add_edid_modes(connector, edid);
+	kfree(edid);
+	return ret;
+
+fallback:
+	/*
+	 * In case we cannot retrieve the EDIDs (broken or missing i2c
+	 * bus), fallback on the XGA standards
+	 */
+	ret = drm_add_modes_noedid(connector, 1920, 1200);
+
+	/* And prefer a mode pretty much anyone can handle */
+	drm_set_preferred_mode(connector, 1024, 768);
+
+	return ret;
+}
+
+static const struct drm_connector_helper_funcs simple_bridge_con_helper_funcs = {
+	.get_modes	= simple_bridge_get_modes,
+};
+
+static enum drm_connector_status
+simple_bridge_connector_detect(struct drm_connector *connector, bool force)
+{
+	struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
+
+	/*
+	 * Even if we have an I2C bus, we can't assume that the cable
+	 * is disconnected if drm_probe_ddc fails. Some cables don't
+	 * wire the DDC pins, or the I2C bus might not be working at
+	 * all.
+	 */
+	if (sbridge->ddc && drm_probe_ddc(sbridge->ddc))
+		return connector_status_connected;
+
+	return connector_status_unknown;
+}
+
+static const struct drm_connector_funcs simple_bridge_con_funcs = {
+	.detect			= simple_bridge_connector_detect,
+	.fill_modes		= drm_helper_probe_single_connector_modes,
+	.destroy		= drm_connector_cleanup,
+	.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 int simple_bridge_attach(struct drm_bridge *bridge,
+				enum drm_bridge_attach_flags flags)
+{
+	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
+	int ret;
+
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
+	if (!bridge->encoder) {
+		DRM_ERROR("Missing encoder\n");
+		return -ENODEV;
+	}
+
+	drm_connector_helper_add(&sbridge->connector,
+				 &simple_bridge_con_helper_funcs);
+	ret = drm_connector_init_with_ddc(bridge->dev, &sbridge->connector,
+					  &simple_bridge_con_funcs,
+					  DRM_MODE_CONNECTOR_VGA,
+					  sbridge->ddc);
+	if (ret) {
+		DRM_ERROR("Failed to initialize connector\n");
+		return ret;
+	}
+
+	drm_connector_attach_encoder(&sbridge->connector,
+					  bridge->encoder);
+
+	return 0;
+}
+
+static void simple_bridge_enable(struct drm_bridge *bridge)
+{
+	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
+	int ret = 0;
+
+	if (sbridge->vdd)
+		ret = regulator_enable(sbridge->vdd);
+
+	if (ret)
+		DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
+}
+
+static void simple_bridge_disable(struct drm_bridge *bridge)
+{
+	struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
+
+	if (sbridge->vdd)
+		regulator_disable(sbridge->vdd);
+}
+
+static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
+	.attach		= simple_bridge_attach,
+	.enable		= simple_bridge_enable,
+	.disable	= simple_bridge_disable,
+};
+
+static struct i2c_adapter *simple_bridge_retrieve_ddc(struct device *dev)
+{
+	struct device_node *phandle, *remote;
+	struct i2c_adapter *ddc;
+
+	remote = of_graph_get_remote_node(dev->of_node, 1, -1);
+	if (!remote)
+		return ERR_PTR(-EINVAL);
+
+	phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
+	of_node_put(remote);
+	if (!phandle)
+		return ERR_PTR(-ENODEV);
+
+	ddc = of_get_i2c_adapter_by_node(phandle);
+	of_node_put(phandle);
+	if (!ddc)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	return ddc;
+}
+
+static int simple_bridge_probe(struct platform_device *pdev)
+{
+	struct simple_bridge *sbridge;
+
+	sbridge = devm_kzalloc(&pdev->dev, sizeof(*sbridge), GFP_KERNEL);
+	if (!sbridge)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, sbridge);
+
+	sbridge->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
+	if (IS_ERR(sbridge->vdd)) {
+		int ret = PTR_ERR(sbridge->vdd);
+		if (ret == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		sbridge->vdd = NULL;
+		dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
+	}
+
+	sbridge->ddc = simple_bridge_retrieve_ddc(&pdev->dev);
+	if (IS_ERR(sbridge->ddc)) {
+		if (PTR_ERR(sbridge->ddc) == -ENODEV) {
+			dev_dbg(&pdev->dev,
+				"No i2c bus specified. Disabling EDID readout\n");
+			sbridge->ddc = NULL;
+		} else {
+			dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
+			return PTR_ERR(sbridge->ddc);
+		}
+	}
+
+	sbridge->bridge.funcs = &simple_bridge_bridge_funcs;
+	sbridge->bridge.of_node = pdev->dev.of_node;
+	sbridge->bridge.timings = of_device_get_match_data(&pdev->dev);
+
+	drm_bridge_add(&sbridge->bridge);
+
+	return 0;
+}
+
+static int simple_bridge_remove(struct platform_device *pdev)
+{
+	struct simple_bridge *sbridge = platform_get_drvdata(pdev);
+
+	drm_bridge_remove(&sbridge->bridge);
+
+	if (sbridge->ddc)
+		i2c_put_adapter(sbridge->ddc);
+
+	return 0;
+}
+
+/*
+ * We assume the ADV7123 DAC is the "default" for historical reasons
+ * Information taken from the ADV7123 datasheet, revision D.
+ * NOTE: the ADV7123EP seems to have other timings and need a new timings
+ * set if used.
+ */
+static const struct drm_bridge_timings default_bridge_timings = {
+	/* Timing specifications, datasheet page 7 */
+	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
+	.setup_time_ps = 500,
+	.hold_time_ps = 1500,
+};
+
+/*
+ * Information taken from the THS8134, THS8134A, THS8134B datasheet named
+ * "SLVS205D", dated May 1990, revised March 2000.
+ */
+static const struct drm_bridge_timings ti_ths8134_bridge_timings = {
+	/* From timing diagram, datasheet page 9 */
+	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
+	/* From datasheet, page 12 */
+	.setup_time_ps = 3000,
+	/* I guess this means latched input */
+	.hold_time_ps = 0,
+};
+
+/*
+ * Information taken from the THS8135 datasheet named "SLAS343B", dated
+ * May 2001, revised April 2013.
+ */
+static const struct drm_bridge_timings ti_ths8135_bridge_timings = {
+	/* From timing diagram, datasheet page 14 */
+	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
+	/* From datasheet, page 16 */
+	.setup_time_ps = 2000,
+	.hold_time_ps = 500,
+};
+
+static const struct of_device_id simple_bridge_match[] = {
+	{
+		.compatible = "dumb-vga-dac",
+		.data = NULL,
+	},
+	{
+		.compatible = "adi,adv7123",
+		.data = &default_bridge_timings,
+	},
+	{
+		.compatible = "ti,ths8135",
+		.data = &ti_ths8135_bridge_timings,
+	},
+	{
+		.compatible = "ti,ths8134",
+		.data = &ti_ths8134_bridge_timings,
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, simple_bridge_match);
+
+static struct platform_driver simple_bridge_driver = {
+	.probe	= simple_bridge_probe,
+	.remove	= simple_bridge_remove,
+	.driver		= {
+		.name		= "simple-bridge",
+		.of_match_table	= simple_bridge_match,
+	},
+};
+module_platform_driver(simple_bridge_driver);
+
+MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
+MODULE_DESCRIPTION("Simple DRM bridge driver");
+MODULE_LICENSE("GPL");