1 files changed, 300 insertions, 0 deletions
diff --git a/drivers/gpu/drm/bridge/dumb-vga-dac.c b/drivers/gpu/drm/bridge/dumb-vga-dac.c
new file mode 100644
index 000000000..9b706789a
--- /dev/null
+++ b/drivers/gpu/drm/bridge/dumb-vga-dac.c
@@ -0,0 +1,300 @@
+/*
+ * Copyright (C) 2015-2016 Free Electrons
+ * Copyright (C) 2015-2016 NextThing Co
+ *
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_graph.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
+
+struct dumb_vga {
+	struct drm_bridge	bridge;
+	struct drm_connector	connector;
+
+	struct i2c_adapter	*ddc;
+	struct regulator	*vdd;
+};
+
+static inline struct dumb_vga *
+drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct dumb_vga, bridge);
+}
+
+static inline struct dumb_vga *
+drm_connector_to_dumb_vga(struct drm_connector *connector)
+{
+	return container_of(connector, struct dumb_vga, connector);
+}
+
+static int dumb_vga_get_modes(struct drm_connector *connector)
+{
+	struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
+	struct edid *edid;
+	int ret;
+
+	if (IS_ERR(vga->ddc))
+		goto fallback;
+
+	edid = drm_get_edid(connector, vga->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 dumb_vga_con_helper_funcs = {
+	.get_modes	= dumb_vga_get_modes,
+};
+
+static enum drm_connector_status
+dumb_vga_connector_detect(struct drm_connector *connector, bool force)
+{
+	struct dumb_vga *vga = drm_connector_to_dumb_vga(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 (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
+		return connector_status_connected;
+
+	return connector_status_unknown;
+}
+
+static const struct drm_connector_funcs dumb_vga_con_funcs = {
+	.detect			= dumb_vga_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 dumb_vga_attach(struct drm_bridge *bridge)
+{
+	struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
+	int ret;
+
+	if (!bridge->encoder) {
+		DRM_ERROR("Missing encoder\n");
+		return -ENODEV;
+	}
+
+	drm_connector_helper_add(&vga->connector,
+				 &dumb_vga_con_helper_funcs);
+	ret = drm_connector_init(bridge->dev, &vga->connector,
+				 &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
+	if (ret) {
+		DRM_ERROR("Failed to initialize connector\n");
+		return ret;
+	}
+
+	drm_connector_attach_encoder(&vga->connector,
+					  bridge->encoder);
+
+	return 0;
+}
+
+static void dumb_vga_enable(struct drm_bridge *bridge)
+{
+	struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
+	int ret = 0;
+
+	if (vga->vdd)
+		ret = regulator_enable(vga->vdd);
+
+	if (ret)
+		DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
+}
+
+static void dumb_vga_disable(struct drm_bridge *bridge)
+{
+	struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
+
+	if (vga->vdd)
+		regulator_disable(vga->vdd);
+}
+
+static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
+	.attach		= dumb_vga_attach,
+	.enable		= dumb_vga_enable,
+	.disable	= dumb_vga_disable,
+};
+
+static struct i2c_adapter *dumb_vga_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 dumb_vga_probe(struct platform_device *pdev)
+{
+	struct dumb_vga *vga;
+
+	vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
+	if (!vga)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, vga);
+
+	vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
+	if (IS_ERR(vga->vdd)) {
+		int ret = PTR_ERR(vga->vdd);
+		if (ret == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		vga->vdd = NULL;
+		dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
+	}
+
+	vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
+	if (IS_ERR(vga->ddc)) {
+		if (PTR_ERR(vga->ddc) == -ENODEV) {
+			dev_dbg(&pdev->dev,
+				"No i2c bus specified. Disabling EDID readout\n");
+		} else {
+			dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
+			return PTR_ERR(vga->ddc);
+		}
+	}
+
+	vga->bridge.funcs = &dumb_vga_bridge_funcs;
+	vga->bridge.of_node = pdev->dev.of_node;
+	vga->bridge.timings = of_device_get_match_data(&pdev->dev);
+
+	drm_bridge_add(&vga->bridge);
+
+	return 0;
+}
+
+static int dumb_vga_remove(struct platform_device *pdev)
+{
+	struct dumb_vga *vga = platform_get_drvdata(pdev);
+
+	drm_bridge_remove(&vga->bridge);
+
+	if (!IS_ERR(vga->ddc))
+		i2c_put_adapter(vga->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_dac_timings = {
+	/* Timing specifications, datasheet page 7 */
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_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_dac_timings = {
+	/* From timing diagram, datasheet page 9 */
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_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_dac_timings = {
+	/* From timing diagram, datasheet page 14 */
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	/* From datasheet, page 16 */
+	.setup_time_ps = 2000,
+	.hold_time_ps = 500,
+};
+
+static const struct of_device_id dumb_vga_match[] = {
+	{
+		.compatible = "dumb-vga-dac",
+		.data = NULL,
+	},
+	{
+		.compatible = "adi,adv7123",
+		.data = &default_dac_timings,
+	},
+	{
+		.compatible = "ti,ths8135",
+		.data = &ti_ths8135_dac_timings,
+	},
+	{
+		.compatible = "ti,ths8134",
+		.data = &ti_ths8134_dac_timings,
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, dumb_vga_match);
+
+static struct platform_driver dumb_vga_driver = {
+	.probe	= dumb_vga_probe,
+	.remove	= dumb_vga_remove,
+	.driver		= {
+		.name		= "dumb-vga-dac",
+		.of_match_table	= dumb_vga_match,
+	},
+};
+module_platform_driver(dumb_vga_driver);
+
+MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
+MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
+MODULE_LICENSE("GPL");