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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2015-2016 Free Electrons
   4  * Copyright (C) 2015-2016 NextThing Co
   5  *
   6  * Maxime Ripard <maxime.ripard@free-electrons.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/of_device.h>
  11 #include <linux/of_graph.h>
  12 #include <linux/regulator/consumer.h>
  13
  14 #include <drm/drm_atomic_helper.h>
  15 #include <drm/drm_bridge.h>
  16 #include <drm/drm_crtc.h>
  17 #include <drm/drm_print.h>
  18 #include <drm/drm_probe_helper.h>
  19
  20 struct dumb_vga {
  21         struct drm_bridge       bridge;
  22         struct drm_connector    connector;
  23
  24         struct i2c_adapter      *ddc;
  25         struct regulator        *vdd;
  26 };
  27
  28 static inline struct dumb_vga *
  29 drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
  30 {
  31         return container_of(bridge, struct dumb_vga, bridge);
  32 }
  33
  34 static inline struct dumb_vga *
  35 drm_connector_to_dumb_vga(struct drm_connector *connector)
  36 {
  37         return container_of(connector, struct dumb_vga, connector);
  38 }
  39
  40 static int dumb_vga_get_modes(struct drm_connector *connector)
  41 {
  42         struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
  43         struct edid *edid;
  44         int ret;
  45
  46         if (!vga->ddc)
  47                 goto fallback;
  48
  49         edid = drm_get_edid(connector, vga->ddc);
  50         if (!edid) {
  51                 DRM_INFO("EDID readout failed, falling back to standard modes\n");
  52                 goto fallback;
  53         }
  54
  55         drm_connector_update_edid_property(connector, edid);
  56         ret = drm_add_edid_modes(connector, edid);
  57         kfree(edid);
  58         return ret;
  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 (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_with_ddc(bridge->dev, &vga->connector,
 116                                           &dumb_vga_con_funcs,
 117                                           DRM_MODE_CONNECTOR_VGA,
 118                                           vga->ddc);
 119         if (ret) {
 120                 DRM_ERROR("Failed to initialize connector\n");
 121                 return ret;
 122         }
 123
 124         drm_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                         vga->ddc = NULL;
 202                 } else {
 203                         dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n");
 204                         return PTR_ERR(vga->ddc);
 205                 }
 206         }
 207
 208         vga->bridge.funcs = &dumb_vga_bridge_funcs;
 209         vga->bridge.of_node = pdev->dev.of_node;
 210         vga->bridge.timings = of_device_get_match_data(&pdev->dev);
 211
 212         drm_bridge_add(&vga->bridge);
 213
 214         return 0;
 215 }
 216
 217 static int dumb_vga_remove(struct platform_device *pdev)
 218 {
 219         struct dumb_vga *vga = platform_get_drvdata(pdev);
 220
 221         drm_bridge_remove(&vga->bridge);
 222
 223         if (vga->ddc)
 224                 i2c_put_adapter(vga->ddc);
 225
 226         return 0;
 227 }
 228
 229 /*
 230  * We assume the ADV7123 DAC is the "default" for historical reasons
 231  * Information taken from the ADV7123 datasheet, revision D.
 232  * NOTE: the ADV7123EP seems to have other timings and need a new timings
 233  * set if used.
 234  */
 235 static const struct drm_bridge_timings default_dac_timings = {
 236         /* Timing specifications, datasheet page 7 */
 237         .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 238         .setup_time_ps = 500,
 239         .hold_time_ps = 1500,
 240 };
 241
 242 /*
 243  * Information taken from the THS8134, THS8134A, THS8134B datasheet named
 244  * "SLVS205D", dated May 1990, revised March 2000.
 245  */
 246 static const struct drm_bridge_timings ti_ths8134_dac_timings = {
 247         /* From timing diagram, datasheet page 9 */
 248         .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 249         /* From datasheet, page 12 */
 250         .setup_time_ps = 3000,
 251         /* I guess this means latched input */
 252         .hold_time_ps = 0,
 253 };
 254
 255 /*
 256  * Information taken from the THS8135 datasheet named "SLAS343B", dated
 257  * May 2001, revised April 2013.
 258  */
 259 static const struct drm_bridge_timings ti_ths8135_dac_timings = {
 260         /* From timing diagram, datasheet page 14 */
 261         .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 262         /* From datasheet, page 16 */
 263         .setup_time_ps = 2000,
 264         .hold_time_ps = 500,
 265 };
 266
 267 static const struct of_device_id dumb_vga_match[] = {
 268         {
 269                 .compatible = "dumb-vga-dac",
 270                 .data = NULL,
 271         },
 272         {
 273                 .compatible = "adi,adv7123",
 274                 .data = &default_dac_timings,
 275         },
 276         {
 277                 .compatible = "ti,ths8135",
 278                 .data = &ti_ths8135_dac_timings,
 279         },
 280         {
 281                 .compatible = "ti,ths8134",
 282                 .data = &ti_ths8134_dac_timings,
 283         },
 284         {},
 285 };
 286 MODULE_DEVICE_TABLE(of, dumb_vga_match);
 287
 288 static struct platform_driver dumb_vga_driver = {
 289         .probe  = dumb_vga_probe,
 290         .remove = dumb_vga_remove,
 291         .driver         = {
 292                 .name           = "dumb-vga-dac",
 293                 .of_match_table = dumb_vga_match,
 294         },
 295 };
 296 module_platform_driver(dumb_vga_driver);
 297
 298 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
 299 MODULE_DESCRIPTION("Dumb VGA DAC bridge driver");
 300 MODULE_LICENSE("GPL");