This adds a very small and simple driver to read a virtual
display characteristic from the device tree and reflect it
back into DRM so a display driver in a virtual environment
knows how to configure its output.
This was created for the ARM RTSM aemv8a emulator as a way
forward to convert all ARM reference designs to use the
PL11x DRM driver.
Cc: Liviu Dudau <Liviu.Dudau@xxxxxxx>
Cc: Ryan Harkin <ryan.harkin@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
drivers/gpu/drm/bridge/Kconfig | 10 ++
drivers/gpu/drm/bridge/Makefile | 1 +
drivers/gpu/drm/bridge/virtual-display.c | 186 +++++++++++++++++++++++
3 files changed, 197 insertions(+)
create mode 100644 drivers/gpu/drm/bridge/virtual-display.c
diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index fa2c7997e2fd..cfb61305b3f6 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -126,6 +126,16 @@ config DRM_TI_TFP410
---help---
Texas Instruments TFP410 DVI/HDMI Transmitter driver
+config DRM_VIRTUAL_DISPLAY_BRIDGE
+ tristate "Virtual Display Bridge support"
+ depends on OF
+ select DRM_KMS_HELPER
+ select VIDEOMODE_HELPERS
+ help
+ Support for virtualized environments where the avilable
+ resolution is controlled by software configuration in
+ the device tree.
+
source "drivers/gpu/drm/bridge/analogix/Kconfig"
source "drivers/gpu/drm/bridge/adv7511/Kconfig"
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 35f88d48ec20..2bdf67d98972 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -14,4 +14,5 @@ obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
+obj-$(CONFIG_DRM_VIRTUAL_DISPLAY_BRIDGE) += virtual-display.o
obj-y += synopsys/
diff --git a/drivers/gpu/drm/bridge/virtual-display.c b/drivers/gpu/drm/bridge/virtual-display.c
new file mode 100644
index 000000000000..ab55b3d6be8a
--- /dev/null
+++ b/drivers/gpu/drm/bridge/virtual-display.c
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) Copyright 2018 Linus Walleij <linus.walleij@xxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include <drm/drmP.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_modes.h>
+#include <video/of_display_timing.h>
+
+struct virtenc {
+ struct device *dev;
+ struct drm_device *drm;
+ struct drm_bridge bridge;
+ struct drm_connector connector;
+ struct drm_display_mode mode;
+ u32 bus_flags;
+};
+
+static inline struct virtenc *bridge_to_virtenc(struct drm_bridge *bridge)
+{
+ return container_of(bridge, struct virtenc, bridge);
+}
+
+static inline struct virtenc *connector_to_virtenc(struct drm_connector *con)
+{
+ return container_of(con, struct virtenc, connector);
+}
+
+static enum drm_connector_status
+virtenc_connector_detect(struct drm_connector *connector, bool force)
+{
+ return connector_status_connected;
+}
+
+static const struct drm_connector_funcs virtenc_connector_funcs = {
+ .detect = virtenc_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 virtenc_get_modes(struct drm_connector *connector)
+{
+ struct virtenc *virtenc = connector_to_virtenc(connector);
+ struct drm_display_mode *mode = drm_mode_create(virtenc->drm);
+ u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+ int ret;
+
+ drm_mode_copy(mode, &virtenc->mode);
+ mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+ mode->width_mm = 80;
+ mode->height_mm = 60;
+ drm_mode_set_name(mode);
+
+ drm_mode_probed_add(connector, mode);
+ ret = drm_display_info_set_bus_formats(&connector->display_info,
+ &bus_format, 1);
+ if (ret)
+ return ret;
+
+ return 1;
+}
+
+static enum drm_mode_status virtenc_mode_valid(struct drm_connector *connector,
+ struct drm_display_mode *mode)
+{
+ return MODE_OK;
+}
+
+static const struct drm_connector_helper_funcs
+virtenc_connector_helper_funcs = {
+ .get_modes = virtenc_get_modes,
+ .mode_valid = virtenc_mode_valid,
+};
+
+static void virtenc_bridge_disable(struct drm_bridge *bridge)
+{
+}
+
+static void virtenc_bridge_enable(struct drm_bridge *bridge)
+{
+}
+
+static void virtenc_bridge_mode_set(struct drm_bridge *bridge,
+ struct drm_display_mode *mode,
+ struct drm_display_mode *adj)
+{
+}
+
+static int virtenc_bridge_attach(struct drm_bridge *bridge)
+{
+ struct virtenc *virtenc = bridge_to_virtenc(bridge);
+ struct drm_device *drm = bridge->dev;
+ int ret;
+
+ virtenc->drm = drm;
+ drm_connector_helper_add(&virtenc->connector,
+ &virtenc_connector_helper_funcs);
+
+ if (!drm_core_check_feature(drm, DRIVER_ATOMIC)) {
+ dev_err(virtenc->dev,
+ "Virtual Display bridge driver is only compatible with DRM devices supporting atomic updates\n");
+ return -ENOTSUPP;
+ }
+
+ ret = drm_connector_init(drm, &virtenc->connector,
+ &virtenc_connector_funcs,
+ DRM_MODE_CONNECTOR_VIRTUAL);
+ if (ret)
+ return ret;
+
+ virtenc->connector.polled = DRM_CONNECTOR_POLL_CONNECT;
+
+ drm_mode_connector_attach_encoder(&virtenc->connector, bridge->encoder);
+
+ return 0;
+}
+
+static const struct drm_bridge_funcs virtenc_bridge_funcs = {
+ .attach = virtenc_bridge_attach,
+ .mode_set = virtenc_bridge_mode_set,
+ .disable = virtenc_bridge_disable,
+ .enable = virtenc_bridge_enable,
+};
+
+static int virtenc_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct virtenc *virtenc;
+ int ret;
+
+ virtenc = devm_kzalloc(dev, sizeof(*virtenc), GFP_KERNEL);
+ if (!virtenc)
+ return -ENOMEM;
+
+ ret = of_get_drm_display_mode(np, &virtenc->mode,
+ &virtenc->bus_flags,
+ 0);
+ if (ret)
+ return ret;
+
+ virtenc->dev = dev;
+ virtenc->bridge.funcs = &virtenc_bridge_funcs;
+ virtenc->bridge.of_node = dev->of_node;
+ drm_bridge_add(&virtenc->bridge);
+ platform_set_drvdata(pdev, virtenc);
+ dev_info(dev, "added virtual display bridge\n");
+
+ return 0;
+}
+
+static int virtenc_remove(struct platform_device *pdev)
+
+{
+ struct virtenc *virtenc = platform_get_drvdata(pdev);
+
+ drm_bridge_remove(&virtenc->bridge);
+
+ return 0;
+}
+
+static const struct of_device_id virtenc_dt_ids[] = {
+ { .compatible = "virtual-display-bridge", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, virtenc_dt_ids);
+
+static struct platform_driver virtenc_driver = {
+ .driver = {
+ .name = "virtenc",
+ .of_match_table = virtenc_dt_ids,
+ },
+ .probe = virtenc_probe,
+ .remove = virtenc_remove,
+};
+module_platform_driver(virtenc_driver);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Virtual Display Bridge");
+MODULE_LICENSE("GPL");
--
2.17.1
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