[PATCH RFC 1/4] drm/panel: add driver for simulated panel

[Jessica Zhang]

Add a driver for simulating panels. This module also supports a mode
parameter for users to specify a custom mode. If no custom mode is set,
it will fall back to a custom, hard-coded mode.

Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
---
 drivers/gpu/drm/panel/Kconfig            |   9 ++
 drivers/gpu/drm/panel/Makefile           |   1 +
 drivers/gpu/drm/panel/panel-simulation.c | 147 +++++++++++++++++++++++++++++++
 3 files changed, 157 insertions(+)

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 99e14dc212ecb..d711ec170c586 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -107,6 +107,15 @@ config DRM_PANEL_SIMPLE
 	  that it can be automatically turned off when the panel goes into a
 	  low power state.
 
+config DRM_PANEL_SIMULATION
+	tristate "support for simulation panels"
+	depends on DRM_MIPI_DSI
+	help
+	  DRM panel driver for simulated DSI panels. Enabling this config will
+	  cause the physical panel driver to not be attached to the DT panel
+	  node. After the kernel boots, users can load the module and specify a
+	  custom mode using the driver modparams.
+
 config DRM_PANEL_EDP
 	tristate "support for simple Embedded DisplayPort panels"
 	depends on OF
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index d10c3de51c6db..5bc55357714ad 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_DRM_PANEL_BOE_TV101WUM_NL6) += panel-boe-tv101wum-nl6.o
 obj-$(CONFIG_DRM_PANEL_DSI_CM) += panel-dsi-cm.o
 obj-$(CONFIG_DRM_PANEL_LVDS) += panel-lvds.o
 obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
+obj-$(CONFIG_DRM_PANEL_SIMULATION) += panel-simulation.o
 obj-$(CONFIG_DRM_PANEL_EDP) += panel-edp.o
 obj-$(CONFIG_DRM_PANEL_EBBG_FT8719) += panel-ebbg-ft8719.o
 obj-$(CONFIG_DRM_PANEL_ELIDA_KD35T133) += panel-elida-kd35t133.o
diff --git a/drivers/gpu/drm/panel/panel-simulation.c b/drivers/gpu/drm/panel/panel-simulation.c
new file mode 100644
index 0000000000000..081c03bea188d
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-simulation.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_panel.h>
+
+static char sim_panel_mode[PATH_MAX];
+
+module_param_string(mode, sim_panel_mode, sizeof(sim_panel_mode), 0644);
+MODULE_PARM_DESC(mode, "Sim panel mode");
+
+struct panel_simulation {
+	struct drm_panel base;
+	struct platform_device *platform;
+} *sim_panel;
+
+static struct drm_display_mode panel_simulation_mode = {
+	.clock = 345830,
+	.hdisplay = 1080,
+	.hsync_start = 1175,
+	.hsync_end = 1176,
+	.htotal = 1216,
+	.vdisplay = 2340,
+	.vsync_start = 2365,
+	.vsync_end = 2366,
+	.vtotal = 2370,
+	.width_mm = 0,
+	.height_mm = 0,
+	.type = DRM_MODE_TYPE_DRIVER,
+};
+
+static int panel_simulation_parse_mode(void)
+{
+	int count;
+	struct drm_display_mode user_mode = { 0 };
+	unsigned int vrefresh;
+
+	if (sim_panel_mode[0] == '\0')
+		return 0;
+
+	count = sscanf(sim_panel_mode, "%hu,%hu,%hu,%hu,%hu,%hu,%hu,%hu-%u",
+			     &user_mode.hdisplay, &user_mode.hsync_start,
+			     &user_mode.hsync_end, &user_mode.htotal,
+			     &user_mode.vdisplay, &user_mode.vsync_start,
+			     &user_mode.vsync_end, &user_mode.vtotal, &vrefresh);
+
+	if (count != 9)
+		return -EINVAL;
+
+	user_mode.clock = user_mode.htotal * user_mode.vtotal * vrefresh / 1000;
+	memcpy(&panel_simulation_mode, &user_mode, sizeof(struct drm_display_mode));
+
+	return 0;
+}
+
+static int panel_simulation_get_modes(struct drm_panel *panel,
+				    struct drm_connector *connector)
+{
+	struct drm_display_mode *mode;
+	int ret;
+
+	ret = panel_simulation_parse_mode();
+
+	mode = drm_mode_duplicate(connector->dev, &panel_simulation_mode);
+	if (!mode)
+		return -ENOMEM;
+
+	drm_mode_set_name(mode);
+	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+	connector->display_info.width_mm = mode->width_mm;
+	connector->display_info.height_mm = mode->height_mm;
+	drm_mode_probed_add(connector, mode);
+
+	return 1;
+}
+
+static const struct drm_panel_funcs panel_simulation_funcs = {
+	.get_modes = panel_simulation_get_modes,
+};
+
+static int panel_simulation_probe(struct mipi_dsi_device *dsi)
+{
+	struct panel_simulation *panel;
+	struct device *dev = &dsi->dev;
+	int ret;
+
+	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
+	if (!panel)
+		return -ENOMEM;
+
+	mipi_dsi_set_drvdata(dsi, panel);
+
+	dsi->lanes = 4;
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	dsi->mode_flags = MIPI_DSI_MODE_LPM | MIPI_DSI_CLOCK_NON_CONTINUOUS;
+
+	drm_panel_init(&panel->base, dev, &panel_simulation_funcs, DRM_MODE_CONNECTOR_DSI);
+	drm_panel_add(&panel->base);
+
+	ret = mipi_dsi_attach(dsi);
+	if (ret)
+		drm_panel_remove(&panel->base);
+
+	return ret;
+}
+
+static void panel_simulation_remove(struct mipi_dsi_device *dsi)
+{
+	struct panel_simulation *panel = mipi_dsi_get_drvdata(dsi);
+	int err;
+
+	err = mipi_dsi_detach(dsi);
+	if (err < 0)
+		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
+
+	drm_panel_remove(&panel->base);
+	drm_panel_disable(&panel->base);
+	drm_panel_unprepare(&panel->base);
+}
+
+static void panel_simulation_shutdown(struct mipi_dsi_device *dsi)
+{
+	struct panel_simulation *panel = dev_get_drvdata(&dsi->dev);
+
+	drm_panel_disable(&panel->base);
+	drm_panel_unprepare(&panel->base);
+}
+
+static struct mipi_dsi_driver panel_simulation_driver = {
+	.driver = {
+		.name = "panel_simulation",
+	},
+	.probe = panel_simulation_probe,
+	.remove = panel_simulation_remove,
+	.shutdown = panel_simulation_shutdown,
+};
+module_mipi_dsi_driver(panel_simulation_driver);
+
+MODULE_AUTHOR("Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("DRM Driver for Simulated Panels");
+MODULE_LICENSE("GPL");

-- 
2.43.0