Quelle  simple-bridge.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2015-2016 Free Electrons
 * Copyright (C) 2015-2016 NextThing Co
 *
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_graph.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

#include <drm/drm_atomic_helper.h>
#include <drm/drm_bridge.h>
#include <drm/drm_crtc.h>
#include <drm/drm_edid.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>

struct simple_bridge_info {
 const struct drm_bridge_timings *timings;
 unsigned int connector_type;
};

struct simple_bridge {
 struct drm_bridge bridge;
 struct drm_connector connector;

 const struct simple_bridge_info *info;

 struct drm_bridge *next_bridge;
 struct regulator *vdd;
 struct gpio_desc *enable;
};

static inline struct simple_bridge *
drm_bridge_to_simple_bridge(struct drm_bridge *bridge)
{
 return container_of(bridge, struct simple_bridge, bridge);
}

static inline struct simple_bridge *
drm_connector_to_simple_bridge(struct drm_connector *connector)
{
 return container_of(connector, struct simple_bridge, connector);
}

static int simple_bridge_get_modes(struct drm_connector *connector)
{
 struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
 const struct drm_edid *drm_edid;
 int ret;

 if (sbridge->next_bridge->ops & DRM_BRIDGE_OP_EDID) {
  drm_edid = drm_bridge_edid_read(sbridge->next_bridge, connector);
  if (!drm_edid)
   DRM_INFO("EDID read failed. Fallback to standard modes\n");
 } else {
  drm_edid = NULL;
 }

 drm_edid_connector_update(connector, drm_edid);

 if (!drm_edid) {
  /*
   * In case we cannot retrieve the EDIDs (missing or broken DDC
   * bus from the next bridge), fallback on the XGA standards and
   * prefer a mode pretty much anyone can handle.
 */
  ret = drm_add_modes_noedid(connector, 1920, 1200);
  drm_set_preferred_mode(connector, 1024, 768);
  return ret;
 }

 ret = drm_edid_connector_add_modes(connector);
 drm_edid_free(drm_edid);

 return ret;
}

static const struct drm_connector_helper_funcs simple_bridge_con_helper_funcs = {
 .get_modes = simple_bridge_get_modes,
};

static enum drm_connector_status
simple_bridge_connector_detect(struct drm_connector *connector, bool force)
{
 struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);

 return drm_bridge_detect(sbridge->next_bridge, connector);
}

static const struct drm_connector_funcs simple_bridge_con_funcs = {
 .detect   = simple_bridge_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 simple_bridge_attach(struct drm_bridge *bridge,
    struct drm_encoder *encoder,
    enum drm_bridge_attach_flags flags)
{
 struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
 int ret;

 ret = drm_bridge_attach(encoder, sbridge->next_bridge, bridge,
    DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 if (ret < 0)
  return ret;

 if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
  return 0;

 drm_connector_helper_add(&sbridge->connector,
     &simple_bridge_con_helper_funcs);
 ret = drm_connector_init_with_ddc(bridge->dev, &sbridge->connector,
       &simple_bridge_con_funcs,
       sbridge->info->connector_type,
       sbridge->next_bridge->ddc);
 if (ret) {
  DRM_ERROR("Failed to initialize connector\n");
  return ret;
 }

 drm_connector_attach_encoder(&sbridge->connector, encoder);

 return 0;
}

static void simple_bridge_enable(struct drm_bridge *bridge)
{
 struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
 int ret;

 if (sbridge->vdd) {
  ret = regulator_enable(sbridge->vdd);
  if (ret)
   DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
 }

 gpiod_set_value_cansleep(sbridge->enable, 1);
}

static void simple_bridge_disable(struct drm_bridge *bridge)
{
 struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);

 gpiod_set_value_cansleep(sbridge->enable, 0);

 if (sbridge->vdd)
  regulator_disable(sbridge->vdd);
}

static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
 .attach  = simple_bridge_attach,
 .enable  = simple_bridge_enable,
 .disable = simple_bridge_disable,
};

static int simple_bridge_probe(struct platform_device *pdev)
{
 struct simple_bridge *sbridge;
 struct device_node *remote;

 sbridge = devm_drm_bridge_alloc(&pdev->dev, struct simple_bridge,
     bridge, &simple_bridge_bridge_funcs);
 if (IS_ERR(sbridge))
  return PTR_ERR(sbridge);

 sbridge->info = of_device_get_match_data(&pdev->dev);

 /* Get the next bridge in the pipeline. */
 remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
 if (!remote)
  return -EINVAL;

 sbridge->next_bridge = of_drm_find_bridge(remote);
 of_node_put(remote);

 if (!sbridge->next_bridge) {
  dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
  return -EPROBE_DEFER;
 }

 /* Get the regulator and GPIO resources. */
 sbridge->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
 if (IS_ERR(sbridge->vdd)) {
  int ret = PTR_ERR(sbridge->vdd);
  if (ret == -EPROBE_DEFER)
   return -EPROBE_DEFER;
  sbridge->vdd = NULL;
  dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
 }

 sbridge->enable = devm_gpiod_get_optional(&pdev->dev, "enable",
        GPIOD_OUT_LOW);
 if (IS_ERR(sbridge->enable))
  return dev_err_probe(&pdev->dev, PTR_ERR(sbridge->enable),
         "Unable to retrieve enable GPIO\n");

 /* Register the bridge. */
 sbridge->bridge.of_node = pdev->dev.of_node;
 sbridge->bridge.timings = sbridge->info->timings;

 return devm_drm_bridge_add(&pdev->dev, &sbridge->bridge);
}

/*
 * We assume the ADV7123 DAC is the "default" for historical reasons
 * Information taken from the ADV7123 datasheet, revision D.
 * NOTE: the ADV7123EP seems to have other timings and need a new timings
 * set if used.
 */
static const struct drm_bridge_timings default_bridge_timings = {
 /* Timing specifications, datasheet page 7 */
 .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 .setup_time_ps = 500,
 .hold_time_ps = 1500,
};

/*
 * Information taken from the THS8134, THS8134A, THS8134B datasheet named
 * "SLVS205D", dated May 1990, revised March 2000.
 */
static const struct drm_bridge_timings ti_ths8134_bridge_timings = {
 /* From timing diagram, datasheet page 9 */
 .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 /* From datasheet, page 12 */
 .setup_time_ps = 3000,
 /* I guess this means latched input */
 .hold_time_ps = 0,
};

/*
 * Information taken from the THS8135 datasheet named "SLAS343B", dated
 * May 2001, revised April 2013.
 */
static const struct drm_bridge_timings ti_ths8135_bridge_timings = {
 /* From timing diagram, datasheet page 14 */
 .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 /* From datasheet, page 16 */
 .setup_time_ps = 2000,
 .hold_time_ps = 500,
};

static const struct of_device_id simple_bridge_match[] = {
 {
  .compatible = "dumb-vga-dac",
  .data = &(const struct simple_bridge_info) {
   .connector_type = DRM_MODE_CONNECTOR_VGA,
  },
 }, {
  .compatible = "adi,adv7123",
  .data = &(const struct simple_bridge_info) {
   .timings = &default_bridge_timings,
   .connector_type = DRM_MODE_CONNECTOR_VGA,
  },
 }, {
  .compatible = "ti,opa362",
  .data = &(const struct simple_bridge_info) {
   .connector_type = DRM_MODE_CONNECTOR_Composite,
  },
 }, {
  .compatible = "ti,ths8135",
  .data = &(const struct simple_bridge_info) {
   .timings = &ti_ths8135_bridge_timings,
   .connector_type = DRM_MODE_CONNECTOR_VGA,
  },
 }, {
  .compatible = "ti,ths8134",
  .data = &(const struct simple_bridge_info) {
   .timings = &ti_ths8134_bridge_timings,
   .connector_type = DRM_MODE_CONNECTOR_VGA,
  },
 },
 {},
};
MODULE_DEVICE_TABLE(of, simple_bridge_match);

static struct platform_driver simple_bridge_driver = {
 .probe = simple_bridge_probe,
 .driver  = {
  .name  = "simple-bridge",
  .of_match_table = simple_bridge_match,
 },
};
module_platform_driver(simple_bridge_driver);

MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_DESCRIPTION("Simple DRM bridge driver");
MODULE_LICENSE("GPL");