diff options
Diffstat (limited to 'drivers/gpu/drm/bridge/dumb-vga-dac.c')
| -rw-r--r-- | drivers/gpu/drm/bridge/dumb-vga-dac.c | 223 |
1 files changed, 223 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 000000000000..afec232185a7 --- /dev/null +++ b/drivers/gpu/drm/bridge/dumb-vga-dac.c @@ -0,0 +1,223 @@ +/* + * 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"); |