drivers/gpu/drm/bridge/dumb-vga-dac.c

   1 /*
   2  * Copyright (C) 2015-2016 Free Electrons
   3  * Copyright (C) 2015-2016 NextThing Co
   4  *
   5  * Maxime Ripard <maxime.ripard@free-electrons.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of
  10  * the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/of_graph.h>
  15 #include <linux/regulator/consumer.h>
  16
  17 #include <drm/drmP.h>
  18 #include <drm/drm_atomic_helper.h>
  19 #include <drm/drm_crtc.h>
  20 #include <drm/drm_crtc_helper.h>
  21
  22 struct dumb_vga {
  23         struct drm_bridge       bridge;
  24         struct drm_connector    connector;
  25
  26         struct i2c_adapter      *ddc;
  27         struct regulator        *vdd;
  28 };
  29
  30 static inline struct dumb_vga *
  31 drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
  32 {
  33         return container_of(bridge, struct dumb_vga, bridge);
  34 }
  35
  36 static inline struct dumb_vga *
  37 drm_connector_to_dumb_vga(struct drm_connector *connector)
  38 {
  39         return container_of(connector, struct dumb_vga, connector);
  40 }
  41
  42 static int dumb_vga_get_modes(struct drm_connector *connector)
  43 {
  44         struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
  45         struct edid *edid;
  46         int ret;
  47
  48         if (IS_ERR(vga->ddc))
  49                 goto fallback;
  50
  51         edid = drm_get_edid(connector, vga->ddc);
  52         if (!edid) {
  53                 DRM_INFO("EDID readout failed, falling back to standard modes\n");
  54                 goto fallback;
  55         }
  56
  57         drm_mode_connector_update_edid_property(connector, edid);
  58         ret = drm_add_edid_modes(connector, edid);
  59         kfree(edid);
  60         return ret;
  61
  62 fallback:
  63         /*
  64          * In case we cannot retrieve the EDIDs (broken or missing i2c
  65          * bus), fallback on the XGA standards
  66          */
  67         ret = drm_add_modes_noedid(connector, 1920, 1200);
  68
  69         /* And prefer a mode pretty much anyone can handle */
  70         drm_set_preferred_mode(connector, 1024, 768);
  71
  72         return ret;
  73 }
  74
  75 static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
  76         .get_modes      = dumb_vga_get_modes,
  77 };
  78
  79 static enum drm_connector_status
  80 dumb_vga_connector_detect(struct drm_connector *connector, bool force)
  81 {
  82         struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
  83
  84         /*
  85          * Even if we have an I2C bus, we can't assume that the cable
  86          * is disconnected if drm_probe_ddc fails. Some cables don't
  87          * wire the DDC pins, or the I2C bus might not be working at
  88          * all.
  89          */
  90         if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
  91                 return connector_status_connected;
  92
  93         return connector_status_unknown;
  94 }
  95
  96 static const struct drm_connector_funcs dumb_vga_con_funcs = {
  97         .detect                 = dumb_vga_connector_detect,
  98         .fill_modes             = drm_helper_probe_single_connector_modes,
  99         .destroy                = drm_connector_cleanup,
 100         .reset                  = drm_atomic_helper_connector_reset,
 101         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 102         .atomic_destroy_state   = drm_atomic_helper_connector_destroy_state,
 103 };
 104
 105 static int dumb_vga_attach(struct drm_bridge *bridge)
 106 {
 107         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 108         int ret;
 109
 110         if (!bridge->encoder) {
 111                 DRM_ERROR("Missing encoder\n");
 112                 return -ENODEV;
 113         }
 114
 115         drm_connector_helper_add(&vga->connector,
 116                                  &dumb_vga_con_helper_funcs);
 117         ret = drm_connector_init(bridge->dev, &vga->connector,
 118                                  &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
 119         if (ret) {
 120                 DRM_ERROR("Failed to initialize connector\n");
 121                 return ret;
 122         }
 123
 124         drm_mode_connector_attach_encoder(&vga->connector,
 125                                           bridge->encoder);
 126
 127         return 0;
 128 }
 129
 130 static void dumb_vga_enable(struct drm_bridge *bridge)
 131 {
 132         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 133         int ret = 0;
 134
 135         if (vga->vdd)
 136                 ret = regulator_enable(vga->vdd);
 137
 138         if (ret)
 139                 DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
 140 }
 141
 142 static void dumb_vga_disable(struct drm_bridge *bridge)
 143 {
 144         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 145
 146         if (vga->vdd)
 147                 regulator_disable(vga->vdd);
 148 }
 149
 150 static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
 151         .attach         = dumb_vga_attach,
 152         .enable         = dumb_vga_enable,
 153         .disable        = dumb_vga_disable,
 154 };
 155
 156 static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
 157 {
 158         struct device_node *phandle, *remote;
 159         struct i2c_adapter *ddc;
 160
 161         remote = of_graph_get_remote_node(dev->of_node, 1, -1);
 162         if (!remote)
 163                 return ERR_PTR(-EINVAL);
 164
 165         phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
 166         of_node_put(remote);
 167         if (!phandle)
 168                 return ERR_PTR(-ENODEV);
 169
 170         ddc = of_get_i2c_adapter_by_node(phandle);
 171         of_node_put(phandle);
 172         if (!ddc)
 173                 return ERR_PTR(-EPROBE_DEFER);
 174
 175         return ddc;
 176 }
 177
 178 static int dumb_vga_probe(struct platform_device *pdev)
 179 {
 180         struct dumb_vga *vga;
 181
 182         vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
 183         if (!vga)
 184                 return -ENOMEM;
 185         platform_set_drvdata(pdev, vga);
 186
 187         vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
 188         if (IS_ERR(vga->vdd)) {
 189                 int ret = PTR_ERR(vga->vdd);
 190                 if (ret == -EPROBE_DEFER)
 191                         return -EPROBE_DEFER;
 192                 vga->vdd = NULL;
 193                 dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
 194         }
 195
 196         vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
 197         if (IS_ERR(vga->ddc)) {
 198                 if (PTR_ERR(vga->ddc) == -ENODEV) {
 199                         dev_dbg(&pdev->dev,
 200                                 "No i2c bus specified. Disabling EDID readout\n");
 201                 } else {
 202                         dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
 203                         return PTR_ERR(vga->ddc);
 204                 }
 205         }
 206
 207         vga->bridge.funcs = &dumb_vga_bridge_funcs;
 208         vga->bridge.of_node = pdev->dev.of_node;
 209
 210         drm_bridge_add(&vga->bridge);
 211
 212         return 0;
 213 }
 214
 215 static int dumb_vga_remove(struct platform_device *pdev)
 216 {
 217         struct dumb_vga *vga = platform_get_drvdata(pdev);
 218
 219         drm_bridge_remove(&vga->bridge);
 220
 221         if (!IS_ERR(vga->ddc))
 222                 i2c_put_adapter(vga->ddc);
 223
 224         return 0;
 225 }
 226
 227 static const struct of_device_id dumb_vga_match[] = {
 228         { .compatible = "dumb-vga-dac" },
 229         { .compatible = "adi,adv7123" },
 230         { .compatible = "ti,ths8135" },
 231         {},
 232 };
 233 MODULE_DEVICE_TABLE(of, dumb_vga_match);
 234
 235 static struct platform_driver dumb_vga_driver = {
 236         .probe  = dumb_vga_probe,
 237         .remove = dumb_vga_remove,
 238         .driver         = {
 239                 .name           = "dumb-vga-dac",
 240                 .of_match_table = dumb_vga_match,
 241         },
 242 };
 243 module_platform_driver(dumb_vga_driver);
 244
 245 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 246 MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
 247 MODULE_LICENSE("GPL");