text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * Generic LVDS panel driver
   *
   * Copyright (C) 2016 Laurent Pinchart
   * Copyright (C) 2016 Renesas Electronics Corporation
   *
   * Contact: Laurent Pinchart (laurent.pinchart@ideasonboard.com)
   */
  
  #include <linux/gpio/consumer.h>
  #include <linux/module.h>
  #include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/consumer.h>
  #include <linux/slab.h>
  
  #include <video/display_timing.h>
  #include <video/of_display_timing.h>
  #include <video/videomode.h>
  
  #include <drm/drm_crtc.h>
  #include <drm/drm_panel.h>
  
  struct panel_lvds {
  	struct drm_panel panel;
  	struct device *dev;
  
  	const char *label;
  	unsigned int width;
  	unsigned int height;
  	struct videomode video_mode;
  	unsigned int bus_format;
  	bool data_mirror;
  
  	struct regulator *supply;
  
  	struct gpio_desc *enable_gpio;
  	struct gpio_desc *reset_gpio;
  
  	enum drm_panel_orientation orientation;
  };
  
  static inline struct panel_lvds *to_panel_lvds(struct drm_panel *panel)
  {
  	return container_of(panel, struct panel_lvds, panel);
  }
  
  static int panel_lvds_unprepare(struct drm_panel *panel)
  {
  	struct panel_lvds *lvds = to_panel_lvds(panel);
  
  	if (lvds->enable_gpio)
  		gpiod_set_value_cansleep(lvds->enable_gpio, 0);
  
  	if (lvds->supply)
  		regulator_disable(lvds->supply);
  
  	return 0;
  }
  
  static int panel_lvds_prepare(struct drm_panel *panel)
  {
  	struct panel_lvds *lvds = to_panel_lvds(panel);
  
  	if (lvds->supply) {
  		int err;
  
  		err = regulator_enable(lvds->supply);
  		if (err < 0) {
  			dev_err(lvds->dev, "failed to enable supply: %d\n",
  				err);
  			return err;
  		}
  	}
  
  	if (lvds->enable_gpio)
  		gpiod_set_value_cansleep(lvds->enable_gpio, 1);
  
  	return 0;
  }
  
  static int panel_lvds_get_modes(struct drm_panel *panel,
  				struct drm_connector *connector)
  {
  	struct panel_lvds *lvds = to_panel_lvds(panel);
  	struct drm_display_mode *mode;
  
  	mode = drm_mode_create(connector->dev);
  	if (!mode)
  		return 0;
  
  	drm_display_mode_from_videomode(&lvds->video_mode, mode);
  	mode->type |= DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
  	drm_mode_probed_add(connector, mode);
  
  	connector->display_info.width_mm = lvds->width;
  	connector->display_info.height_mm = lvds->height;
  	drm_display_info_set_bus_formats(&connector->display_info,
  					 &lvds->bus_format, 1);
  	connector->display_info.bus_flags = lvds->data_mirror
  					  ? DRM_BUS_FLAG_DATA_LSB_TO_MSB
  					  : DRM_BUS_FLAG_DATA_MSB_TO_LSB;
  	drm_connector_set_panel_orientation(connector, lvds->orientation);
  
  	return 1;
  }
  
  static const struct drm_panel_funcs panel_lvds_funcs = {
  	.unprepare = panel_lvds_unprepare,
  	.prepare = panel_lvds_prepare,
  	.get_modes = panel_lvds_get_modes,
  };
  
  static int panel_lvds_parse_dt(struct panel_lvds *lvds)
  {
  	struct device_node *np = lvds->dev->of_node;
  	struct display_timing timing;
  	const char *mapping;
  	int ret;
  
  	ret = of_drm_get_panel_orientation(np, &lvds->orientation);
  	if (ret < 0) {
  		dev_err(lvds->dev, "%pOF: failed to get orientation %d\n", np, ret);
  		return ret;
  	}
  
  	ret = of_get_display_timing(np, "panel-timing", &timing);
  	if (ret < 0) {
  		dev_err(lvds->dev, "%pOF: problems parsing panel-timing (%d)\n",
  			np, ret);
  		return ret;
  	}
  
  	videomode_from_timing(&timing, &lvds->video_mode);
  
  	ret = of_property_read_u32(np, "width-mm", &lvds->width);
  	if (ret < 0) {
  		dev_err(lvds->dev, "%pOF: invalid or missing %s DT property\n",
  			np, "width-mm");
  		return -ENODEV;
  	}
  	ret = of_property_read_u32(np, "height-mm", &lvds->height);
  	if (ret < 0) {
  		dev_err(lvds->dev, "%pOF: invalid or missing %s DT property\n",
  			np, "height-mm");
  		return -ENODEV;
  	}
  
  	of_property_read_string(np, "label", &lvds->label);
  
  	ret = of_property_read_string(np, "data-mapping", &mapping);
  	if (ret < 0) {
  		dev_err(lvds->dev, "%pOF: invalid or missing %s DT property\n",
  			np, "data-mapping");
  		return -ENODEV;
  	}
  
  	if (!strcmp(mapping, "jeida-18")) {
  		lvds->bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG;
  	} else if (!strcmp(mapping, "jeida-24")) {
  		lvds->bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA;
  	} else if (!strcmp(mapping, "vesa-24")) {
  		lvds->bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG;
  	} else {
  		dev_err(lvds->dev, "%pOF: invalid or missing %s DT property\n",
  			np, "data-mapping");
  		return -EINVAL;
  	}
  
  	lvds->data_mirror = of_property_read_bool(np, "data-mirror");
  
  	return 0;
  }
  
  static int panel_lvds_probe(struct platform_device *pdev)
  {
  	struct panel_lvds *lvds;
  	int ret;
  
  	lvds = devm_kzalloc(&pdev->dev, sizeof(*lvds), GFP_KERNEL);
  	if (!lvds)
  		return -ENOMEM;
  
  	lvds->dev = &pdev->dev;
  
  	ret = panel_lvds_parse_dt(lvds);
  	if (ret < 0)
  		return ret;
  
  	lvds->supply = devm_regulator_get_optional(lvds->dev, "power");
  	if (IS_ERR(lvds->supply)) {
  		ret = PTR_ERR(lvds->supply);
  
  		if (ret != -ENODEV) {
  			if (ret != -EPROBE_DEFER)
  				dev_err(lvds->dev, "failed to request regulator: %d\n",
  					ret);
  			return ret;
  		}
  
  		lvds->supply = NULL;
  	}
  
  	/* Get GPIOs and backlight controller. */
  	lvds->enable_gpio = devm_gpiod_get_optional(lvds->dev, "enable",
  						     GPIOD_OUT_LOW);
  	if (IS_ERR(lvds->enable_gpio)) {
  		ret = PTR_ERR(lvds->enable_gpio);
  		dev_err(lvds->dev, "failed to request %s GPIO: %d\n",
  			"enable", ret);
  		return ret;
  	}
  
  	lvds->reset_gpio = devm_gpiod_get_optional(lvds->dev, "reset",
  						     GPIOD_OUT_HIGH);
  	if (IS_ERR(lvds->reset_gpio)) {
  		ret = PTR_ERR(lvds->reset_gpio);
  		dev_err(lvds->dev, "failed to request %s GPIO: %d\n",
  			"reset", ret);
  		return ret;
  	}
  
  	/*
  	 * TODO: Handle all power supplies specified in the DT node in a generic
  	 * way for panels that don't care about power supply ordering. LVDS
  	 * panels that require a specific power sequence will need a dedicated
  	 * driver.
  	 */
  
  	/* Register the panel. */
  	drm_panel_init(&lvds->panel, lvds->dev, &panel_lvds_funcs,
  		       DRM_MODE_CONNECTOR_LVDS);
  
  	ret = drm_panel_of_backlight(&lvds->panel);
  	if (ret)
  		return ret;
  
  	drm_panel_add(&lvds->panel);
  
  	dev_set_drvdata(lvds->dev, lvds);
  	return 0;
  }
  
  static int panel_lvds_remove(struct platform_device *pdev)
  {
  	struct panel_lvds *lvds = dev_get_drvdata(&pdev->dev);
  
  	drm_panel_remove(&lvds->panel);
  
  	drm_panel_disable(&lvds->panel);
  
  	return 0;
  }
  
  static const struct of_device_id panel_lvds_of_table[] = {
  	{ .compatible = "panel-lvds", },
  	{ /* Sentinel */ },
  };
  
  MODULE_DEVICE_TABLE(of, panel_lvds_of_table);
  
  static struct platform_driver panel_lvds_driver = {
  	.probe		= panel_lvds_probe,
  	.remove		= panel_lvds_remove,
  	.driver		= {
  		.name	= "panel-lvds",
  		.of_match_table = panel_lvds_of_table,
  	},
  };
  
  module_platform_driver(panel_lvds_driver);
  
  MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
  MODULE_DESCRIPTION("LVDS Panel Driver");
  MODULE_LICENSE("GPL");
  