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_device.h>
  15 #include <linux/of_graph.h>
  16 #include <linux/regulator/consumer.h>
  17
  18 #include <drm/drmP.h>
  19 #include <drm/drm_atomic_helper.h>
  20 #include <drm/drm_crtc.h>
  21 #include <drm/drm_crtc_helper.h>
  22
  23 struct dumb_vga {
  24         struct drm_bridge       bridge;
  25         struct drm_connector    connector;
  26
  27         struct i2c_adapter      *ddc;
  28         struct regulator        *vdd;
  29 };
  30
  31 static inline struct dumb_vga *
  32 drm_bridge_to_dumb_vga(struct drm_bridge *bridge)
  33 {
  34         return container_of(bridge, struct dumb_vga, bridge);
  35 }
  36
  37 static inline struct dumb_vga *
  38 drm_connector_to_dumb_vga(struct drm_connector *connector)
  39 {
  40         return container_of(connector, struct dumb_vga, connector);
  41 }
  42
  43 static int dumb_vga_get_modes(struct drm_connector *connector)
  44 {
  45         struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
  46         struct edid *edid;
  47         int ret;
  48
  49         if (IS_ERR(vga->ddc))
  50                 goto fallback;
  51
  52         edid = drm_get_edid(connector, vga->ddc);
  53         if (!edid) {
  54                 DRM_INFO("EDID readout failed, falling back to standard modes\n");
  55                 goto fallback;
  56         }
  57
  58         drm_connector_update_edid_property(connector, edid);
  59         ret = drm_add_edid_modes(connector, edid);
  60         kfree(edid);
  61         return ret;
  62
  63 fallback:
  64         /*
  65          * In case we cannot retrieve the EDIDs (broken or missing i2c
  66          * bus), fallback on the XGA standards
  67          */
  68         ret = drm_add_modes_noedid(connector, 1920, 1200);
  69
  70         /* And prefer a mode pretty much anyone can handle */
  71         drm_set_preferred_mode(connector, 1024, 768);
  72
  73         return ret;
  74 }
  75
  76 static const struct drm_connector_helper_funcs dumb_vga_con_helper_funcs = {
  77         .get_modes      = dumb_vga_get_modes,
  78 };
  79
  80 static enum drm_connector_status
  81 dumb_vga_connector_detect(struct drm_connector *connector, bool force)
  82 {
  83         struct dumb_vga *vga = drm_connector_to_dumb_vga(connector);
  84
  85         /*
  86          * Even if we have an I2C bus, we can't assume that the cable
  87          * is disconnected if drm_probe_ddc fails. Some cables don't
  88          * wire the DDC pins, or the I2C bus might not be working at
  89          * all.
  90          */
  91         if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc))
  92                 return connector_status_connected;
  93
  94         return connector_status_unknown;
  95 }
  96
  97 static const struct drm_connector_funcs dumb_vga_con_funcs = {
  98         .detect                 = dumb_vga_connector_detect,
  99         .fill_modes             = drm_helper_probe_single_connector_modes,
 100         .destroy                = drm_connector_cleanup,
 101         .reset                  = drm_atomic_helper_connector_reset,
 102         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 103         .atomic_destroy_state   = drm_atomic_helper_connector_destroy_state,
 104 };
 105
 106 static int dumb_vga_attach(struct drm_bridge *bridge)
 107 {
 108         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 109         int ret;
 110
 111         if (!bridge->encoder) {
 112                 DRM_ERROR("Missing encoder\n");
 113                 return -ENODEV;
 114         }
 115
 116         drm_connector_helper_add(&vga->connector,
 117                                  &dumb_vga_con_helper_funcs);
 118         ret = drm_connector_init(bridge->dev, &vga->connector,
 119                                  &dumb_vga_con_funcs, DRM_MODE_CONNECTOR_VGA);
 120         if (ret) {
 121                 DRM_ERROR("Failed to initialize connector\n");
 122                 return ret;
 123         }
 124
 125         drm_connector_attach_encoder(&vga->connector,
 126                                           bridge->encoder);
 127
 128         return 0;
 129 }
 130
 131 static void dumb_vga_enable(struct drm_bridge *bridge)
 132 {
 133         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 134         int ret = 0;
 135
 136         if (vga->vdd)
 137                 ret = regulator_enable(vga->vdd);
 138
 139         if (ret)
 140                 DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
 141 }
 142
 143 static void dumb_vga_disable(struct drm_bridge *bridge)
 144 {
 145         struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 146
 147         if (vga->vdd)
 148                 regulator_disable(vga->vdd);
 149 }
 150
 151 static const struct drm_bridge_funcs dumb_vga_bridge_funcs = {
 152         .attach         = dumb_vga_attach,
 153         .enable         = dumb_vga_enable,
 154         .disable        = dumb_vga_disable,
 155 };
 156
 157 static struct i2c_adapter *dumb_vga_retrieve_ddc(struct device *dev)
 158 {
 159         struct device_node *phandle, *remote;
 160         struct i2c_adapter *ddc;
 161
 162         remote = of_graph_get_remote_node(dev->of_node, 1, -1);
 163         if (!remote)
 164                 return ERR_PTR(-EINVAL);
 165
 166         phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
 167         of_node_put(remote);
 168         if (!phandle)
 169                 return ERR_PTR(-ENODEV);
 170
 171         ddc = of_get_i2c_adapter_by_node(phandle);
 172         of_node_put(phandle);
 173         if (!ddc)
 174                 return ERR_PTR(-EPROBE_DEFER);
 175
 176         return ddc;
 177 }
 178
 179 static int dumb_vga_probe(struct platform_device *pdev)
 180 {
 181         struct dumb_vga *vga;
 182
 183         vga = devm_kzalloc(&pdev->dev, sizeof(*vga), GFP_KERNEL);
 184         if (!vga)
 185                 return -ENOMEM;
 186         platform_set_drvdata(pdev, vga);
 187
 188         vga->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
 189         if (IS_ERR(vga->vdd)) {
 190                 int ret = PTR_ERR(vga->vdd);
 191                 if (ret == -EPROBE_DEFER)
 192                         return -EPROBE_DEFER;
 193                 vga->vdd = NULL;
 194                 dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
 195         }
 196
 197         vga->ddc = dumb_vga_retrieve_ddc(&pdev->dev);
 198         if (IS_ERR(vga->ddc)) {
 199                 if (PTR_ERR(vga->ddc) == -ENODEV) {
 200                         dev_dbg(&pdev->dev,
 201                                 "No i2c bus specified. Disabling EDID readout\n");
 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 (!IS_ERR(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         .sampling_edge = DRM_BUS_FLAG_PIXDATA_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         .sampling_edge = DRM_BUS_FLAG_PIXDATA_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         .sampling_edge = DRM_BUS_FLAG_PIXDATA_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");