Add support for panels connected on a DPI bus.
This implementation includes DRM encoder/connector creation and attachment
to the DRM device so that the only thing needed to access such a panel is
to implement a DPI host in your driver and define the appropriate node in
your DT (under the DPI node).

Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 drivers/gpu/drm/panel/panel-simple.c | 277 +++++++++++++++++++++++++++++++++++
 1 file changed, 277 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c 
b/drivers/gpu/drm/panel/panel-simple.c
index 11bff3f..fd448ca 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -30,7 +30,9 @@

 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_mipi_dsi.h>
+#include <drm/drm_mipi_dpi.h>
 #include <drm/drm_panel.h>

 struct panel_desc {
@@ -851,6 +853,275 @@ static struct mipi_dsi_driver panel_simple_dsi_driver = {
        .shutdown = panel_simple_dsi_shutdown,
 };

+struct panel_desc_dpi {
+       struct panel_desc desc;
+
+       enum video_bus_format format;
+};
+
+struct panel_dpi {
+       struct drm_encoder encoder;
+       struct drm_connector connector;
+       int dpms_mode;
+
+       struct mipi_dpi_device *dev;
+};
+
+static const struct of_device_id dpi_of_match[] = {
+       {
+               /* sentinel */
+       }
+};
+MODULE_DEVICE_TABLE(of, dsi_of_match);
+
+static inline struct panel_dpi *
+drm_encoder_to_panel_dpi(struct drm_encoder *encoder)
+{
+       return container_of(encoder, struct panel_dpi, encoder);
+}
+
+static void panel_dpi_encoder_dpms(struct drm_encoder *encoder, int mode)
+{
+       struct panel_dpi *dpanel = drm_encoder_to_panel_dpi(encoder);
+       struct panel_simple *panel = mipi_dpi_get_drvdata(dpanel->dev);
+
+       if (mode != DRM_MODE_DPMS_ON)
+               mode = DRM_MODE_DPMS_OFF;
+
+       if (mode == dpanel->dpms_mode)
+               return;
+
+       switch (mode) {
+       case DRM_MODE_DPMS_ON:
+               drm_panel_prepare(&panel->base);
+               drm_panel_enable(&panel->base);
+               mipi_dpi_enable(dpanel->dev);
+               break;
+       case DRM_MODE_DPMS_STANDBY:
+       case DRM_MODE_DPMS_SUSPEND:
+       case DRM_MODE_DPMS_OFF:
+               mipi_dpi_disable(dpanel->dev);
+               drm_panel_disable(&panel->base);
+               drm_panel_unprepare(&panel->base);
+               break;
+       }
+
+       dpanel->dpms_mode = mode;
+}
+
+static bool panel_dpi_encoder_mode_fixup(struct drm_encoder *encoder,
+                                const struct drm_display_mode *mode,
+                                struct drm_display_mode *adjusted_mode)
+{
+       return true;
+}
+
+static void panel_dpi_encoder_mode_set(struct drm_encoder *encoder,
+                              struct drm_display_mode *mode,
+                              struct drm_display_mode *adjusted)
+{
+}
+
+static void panel_dpi_encoder_prepare(struct drm_encoder *encoder)
+{
+       panel_dpi_encoder_dpms(encoder, DRM_MODE_DPMS_OFF);
+}
+
+static void panel_dpi_encoder_commit(struct drm_encoder *encoder)
+{
+       panel_dpi_encoder_dpms(encoder, DRM_MODE_DPMS_ON);
+}
+
+static const struct drm_encoder_helper_funcs panel_dpi_encoder_helper_funcs = {
+       .dpms = panel_dpi_encoder_dpms,
+       .mode_fixup = panel_dpi_encoder_mode_fixup,
+       .mode_set = panel_dpi_encoder_mode_set,
+       .prepare = panel_dpi_encoder_prepare,
+       .commit = panel_dpi_encoder_commit,
+};
+
+static const struct drm_encoder_funcs panel_dpi_encoder_funcs = {
+       .destroy = drm_encoder_cleanup,
+};
+
+static inline struct panel_dpi *
+drm_connector_to_panel_dpi(struct drm_connector *connector)
+{
+       return container_of(connector, struct panel_dpi, connector);
+}
+
+static int panel_dpi_connector_get_modes(struct drm_connector *connector)
+{
+       struct panel_dpi *dpanel = drm_connector_to_panel_dpi(connector);
+       struct panel_simple *panel = mipi_dpi_get_drvdata(dpanel->dev);
+
+       return drm_panel_get_modes(&panel->base);
+}
+
+static struct drm_encoder *
+panel_dpi_connector_best_encoder(struct drm_connector *connector)
+{
+       struct panel_dpi *dpanel = drm_connector_to_panel_dpi(connector);
+
+       return &dpanel->encoder;
+}
+
+static int panel_dpi_connector_mode_valid(struct drm_connector *connector,
+                                         struct drm_display_mode *mode)
+{
+       return MODE_OK;
+}
+
+static const struct drm_connector_helper_funcs 
panel_dpi_connector_helper_funcs = {
+       .get_modes = panel_dpi_connector_get_modes,
+       .mode_valid = panel_dpi_connector_mode_valid,
+       .best_encoder = panel_dpi_connector_best_encoder,
+};
+
+static enum drm_connector_status
+panel_dpi_connector_detect(struct drm_connector *connector, bool force)
+{
+       return connector_status_connected;
+}
+
+static void
+panel_dpi_connector_destroy(struct drm_connector *connector)
+{
+       drm_connector_unregister(connector);
+       drm_connector_cleanup(connector);
+}
+
+static const struct drm_connector_funcs panel_dpi_connector_funcs = {
+       .dpms = drm_helper_connector_dpms,
+       .detect = panel_dpi_connector_detect,
+       .fill_modes = drm_helper_probe_single_connector_modes,
+       .destroy = panel_dpi_connector_destroy,
+};
+
+static int panel_simple_dpi_probe(struct mipi_dpi_device *dpi)
+{
+       const struct panel_desc_dpi *desc;
+       const struct of_device_id *id;
+       struct panel_simple *panel;
+       struct panel_dpi *dpanel;
+       int err;
+
+       id = of_match_node(dpi_of_match, dpi->dev.of_node);
+       if (!id)
+               return -ENODEV;
+
+       desc = id->data;
+
+       dpanel = devm_kzalloc(&dpi->dev, sizeof(*dpanel), GFP_KERNEL);
+       if (!dpanel)
+               return -ENOMEM;
+
+       dpanel->dev = dpi;
+
+       err = panel_simple_probe(&dpi->dev, &desc->desc);
+       if (err < 0)
+               return err;
+
+       dpanel->dpms_mode = DRM_MODE_DPMS_OFF;
+       dpi->supported_formats = &desc->format;
+       dpi->num_supported_formats = 1;
+
+       err = mipi_dpi_attach(dpi);
+       if (err)
+               goto err_panel_remove;
+
+       dpanel->encoder.possible_crtcs = dpi->host->possible_crtcs;
+       drm_encoder_helper_add(&dpanel->encoder,
+                              &panel_dpi_encoder_helper_funcs);
+       err = drm_encoder_init(dpi->host->ddev, &dpanel->encoder,
+                              &panel_dpi_encoder_funcs, DRM_MODE_ENCODER_DPI);
+       if (err)
+               goto err_dpi_detach;
+
+       dpanel->connector.status = connector_status_connected;
+       drm_connector_helper_add(&dpanel->connector,
+                                &panel_dpi_connector_helper_funcs);
+       err = drm_connector_init(dpi->host->ddev, &dpanel->connector,
+                                &panel_dpi_connector_funcs,
+                                DRM_MODE_CONNECTOR_DPI);
+       if (err)
+               goto err_encoder_cleanup;
+
+       panel = mipi_dpi_get_drvdata(dpi);
+       err = drm_panel_attach(&panel->base, &dpanel->connector);
+       if (err)
+               goto err_connector_cleanup;
+
+       err = drm_mode_connector_attach_encoder(&dpanel->connector,
+                                               &dpanel->encoder);
+       if (err)
+               goto err_panel_detach;
+
+       err = drm_connector_register(&dpanel->connector);
+       if (err)
+               goto err_panel_detach;
+
+       drm_reinit_primary_mode_group(dpi->host->ddev);
+       drm_kms_helper_hotplug_event(dpi->host->ddev);
+
+       return 0;
+
+err_panel_detach:
+       drm_panel_detach(&panel->base);
+err_connector_cleanup:
+       drm_connector_cleanup(&dpanel->connector);
+err_encoder_cleanup:
+       drm_encoder_cleanup(&dpanel->encoder);
+err_dpi_detach:
+       mipi_dpi_detach(dpi);
+err_panel_remove:
+       panel_simple_remove(&dpi->dev);
+
+       return err;
+}
+
+static int panel_simple_dpi_remove(struct mipi_dpi_device *dpi)
+{
+       struct panel_simple *panel;
+       struct panel_dpi *dpanel;
+
+       int err;
+
+       panel = mipi_dpi_get_drvdata(dpi);
+       dpanel = drm_connector_to_panel_dpi(panel->base.connector);
+
+       drm_connector_unregister(&dpanel->connector);
+       drm_connector_cleanup(&dpanel->connector);
+
+       drm_panel_detach(&panel->base);
+
+       drm_encoder_cleanup(&dpanel->encoder);
+
+       drm_reinit_primary_mode_group(dpi->host->ddev);
+
+       err = mipi_dpi_detach(dpi);
+       if (err < 0)
+               dev_err(&dpi->dev, "failed to detach from DPI host: %d\n", err);
+
+       return panel_simple_remove(&dpi->dev);
+}
+
+static void panel_simple_dpi_shutdown(struct mipi_dpi_device *dpi)
+{
+       panel_simple_shutdown(&dpi->dev);
+}
+
+static struct mipi_dpi_driver panel_simple_dpi_driver = {
+       .driver = {
+               .name = "panel-simple-dpi",
+               .owner = THIS_MODULE,
+               .of_match_table = dpi_of_match,
+       },
+       .probe = panel_simple_dpi_probe,
+       .remove = panel_simple_dpi_remove,
+       .shutdown = panel_simple_dpi_shutdown,
+};
+
 static int __init panel_simple_init(void)
 {
        int err;
@@ -865,6 +1136,12 @@ static int __init panel_simple_init(void)
                        return err;
        }

+       if (IS_ENABLED(CONFIG_DRM_MIPI_DPI)) {
+               err = mipi_dpi_driver_register(&panel_simple_dpi_driver);
+               if (err < 0)
+                       return err;
+       }
+
        return 0;
 }
 module_init(panel_simple_init);
-- 
1.9.1

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