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         return drm_add_edid_modes(connector, edid);
  59
  60 fallback:
  61         /*
  62          * In case we cannot retrieve the EDIDs (broken or missing i2c
  63          * bus), fallback on the XGA standards
  64          */
  65         ret = drm_add_modes_noedid(connector, 1920, 1200);
  66
  67         /* And prefer a mode pretty much anyone can handle */
  68         drm_set_preferred_mode(connector, 1024, 768);
  69
  70         return ret;
  71 }
  72
  73 static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
  74         .get_modes      = dumb_vga_get_modes,
  75 };
  76
  77 static enum drm_connector_status
  78 dumb_vga_connector_detect(struct drm_connector *connector, bool force)
  79 {
  80         struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
  81
  82         /*
  83          * Even if we have an I2C bus, we can't assume that the cable
  84          * is disconnected if drm_probe_ddc fails. Some cables don't
  85          * wire the DDC pins, or the I2C bus might not be working at
  86          * all.
  87          */
  88         if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
  89                 return connector_status_connected;
  90
  91         return connector_status_unknown;
  92 }
  93
  94 static const struct drm_connector_funcs dumb_vga_con_funcs = {
  95         .detect                 = dumb_vga_connector_detect,
  96         .fill_modes             = drm_helper_probe_single_connector_modes,
  97         .destroy                = drm_connector_cleanup,
  98         .reset                  = drm_atomic_helper_connector_reset,
  99         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 100         .atomic_destroy_state   = drm_atomic_helper_connector_destroy_state,
 101 };
 102
 103 static int dumb_vga_attach(struct drm_bridge *bridge)
 104 {
 105         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 106         int ret;
 107
 108         if (!bridge->encoder) {
 109                 DRM_ERROR("Missing encoder\n");
 110                 return -ENODEV;
 111         }
 112
 113         drm_connector_helper_add(&vga->connector,
 114                                  &dumb_vga_con_helper_funcs);
 115         ret = drm_connector_init(bridge->dev, &vga->connector,
 116                                  &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
 117         if (ret) {
 118                 DRM_ERROR("Failed to initialize connector\n");
 119                 return ret;
 120         }
 121
 122         drm_mode_connector_attach_encoder(&vga->connector,
 123                                           bridge->encoder);
 124
 125         return 0;
 126 }
 127
 128 static void dumb_vga_enable(struct drm_bridge *bridge)
 129 {
 130         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 131         int ret = 0;
 132
 133         if (vga->vdd)
 134                 ret = regulator_enable(vga->vdd);
 135
 136         if (ret)
 137                 DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
 138 }
 139
 140 static void dumb_vga_disable(struct drm_bridge *bridge)
 141 {
 142         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 143
 144         if (vga->vdd)
 145                 regulator_disable(vga->vdd);
 146 }
 147
 148 static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
 149         .attach         = dumb_vga_attach,
 150         .enable         = dumb_vga_enable,
 151         .disable        = dumb_vga_disable,
 152 };
 153
 154 static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
 155 {
 156         struct device_node *phandle, *remote;
 157         struct i2c_adapter *ddc;
 158
 159         remote = of_graph_get_remote_node(dev->of_node, 1, -1);
 160         if (!remote)
 161                 return ERR_PTR(-EINVAL);
 162
 163         phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
 164         of_node_put(remote);
 165         if (!phandle)
 166                 return ERR_PTR(-ENODEV);
 167
 168         ddc = of_get_i2c_adapter_by_node(phandle);
 169         of_node_put(phandle);
 170         if (!ddc)
 171                 return ERR_PTR(-EPROBE_DEFER);
 172
 173         return ddc;
 174 }
 175
 176 static int dumb_vga_probe(struct platform_device *pdev)
 177 {
 178         struct dumb_vga *vga;
 179
 180         vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
 181         if (!vga)
 182                 return -ENOMEM;
 183         platform_set_drvdata(pdev, vga);
 184
 185         vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
 186         if (IS_ERR(vga->vdd)) {
 187                 int ret = PTR_ERR(vga->vdd);
 188                 if (ret == -EPROBE_DEFER)
 189                         return -EPROBE_DEFER;
 190                 vga->vdd = NULL;
 191                 dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
 192         }
 193
 194         vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
 195         if (IS_ERR(vga->ddc)) {
 196                 if (PTR_ERR(vga->ddc) == -ENODEV) {
 197                         dev_dbg(&pdev->dev,
 198                                 "No i2c bus specified. Disabling EDID readout\n");
 199                 } else {
 200                         dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
 201                         return PTR_ERR(vga->ddc);
 202                 }
 203         }
 204
 205         vga->bridge.funcs = &dumb_vga_bridge_funcs;
 206         vga->bridge.of_node = pdev->dev.of_node;
 207
 208         drm_bridge_add(&vga->bridge);
 209
 210         return 0;
 211 }
 212
 213 static int dumb_vga_remove(struct platform_device *pdev)
 214 {
 215         struct dumb_vga *vga = platform_get_drvdata(pdev);
 216
 217         drm_bridge_remove(&vga->bridge);
 218
 219         if (!IS_ERR(vga->ddc))
 220                 i2c_put_adapter(vga->ddc);
 221
 222         return 0;
 223 }
 224
 225 static const struct of_device_id dumb_vga_match[] = {
 226         { .compatible = "dumb-vga-dac" },
 227         { .compatible = "adi,adv7123" },
 228         { .compatible = "ti,ths8135" },
 229         {},
 230 };
 231 MODULE_DEVICE_TABLE(of, dumb_vga_match);
 232
 233 static struct platform_driver dumb_vga_driver = {
 234         .probe  = dumb_vga_probe,
 235         .remove = dumb_vga_remove,
 236         .driver         = {
 237                 .name           = "dumb-vga-dac",
 238                 .of_match_table = dumb_vga_match,
 239         },
 240 };
 241 module_platform_driver(dumb_vga_driver);
 242
 243 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 244 MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
 245 MODULE_LICENSE("GPL");