--- /dev/null
+/*
+ * 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_graph.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;
+};
+
+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_mode_connector_update_edid_property(connector, edid);
+ return drm_add_edid_modes(connector, edid);
+
+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 = {
+ .dpms = drm_atomic_helper_connector_dpms,
+ .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_mode_connector_attach_encoder(&vga->connector,
+ bridge->encoder);
+
+ return 0;
+}
+
+static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
+ .attach = dumb_vga_attach,
+};
+
+static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
+{
+ struct device_node *end_node, *phandle, *remote;
+ struct i2c_adapter *ddc;
+
+ end_node = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
+ if (!end_node) {
+ dev_err(dev, "Missing connector endpoint\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ remote = of_graph_get_remote_port_parent(end_node);
+ of_node_put(end_node);
+ if (!remote) {
+ dev_err(dev, "Enable to parse remote node\n");
+ 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;
+ int ret;
+
+ vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
+ if (!vga)
+ return -ENOMEM;
+ platform_set_drvdata(pdev, vga);
+
+ 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;
+
+ ret = drm_bridge_add(&vga->bridge);
+ if (ret && !IS_ERR(vga->ddc))
+ i2c_put_adapter(vga->ddc);
+
+ return ret;
+}
+
+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;
+}
+
+static const struct of_device_id dumb_vga_match[] = {
+ { .compatible = "dumb-vga-dac" },
+ {},
+};
+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");
projects / cascardo / linux.git / commitdiff