[PATCH RESEND 11/17] drm/spacemit: add Saturn DPU DRM device driver
From: Cody Kang via B4 Relay
Date: Sat Jul 25 2026 - 00:52:49 EST
From: Cody Kang <codykang.hk@xxxxxxxxx>
Add the DRM device for the SpacemiT K3 Saturn display processing unit
and hook the driver up to the build. The SoC has two DPU instances;
each drives one CRTC that scans out a single primary plane in linear
RGB at up to 3840x2160@60 and feeds a downstream DP/eDP controller
over an OF-graph endpoint. Buffers use drm_gem_shmem_helper. The
AFBC/compressed decode path is not exposed and writeback is not
implemented.
Signed-off-by: Cody Kang <codykang.hk@xxxxxxxxx>
---
drivers/gpu/drm/Kconfig | 1 +
drivers/gpu/drm/Makefile | 1 +
drivers/gpu/drm/spacemit/Kconfig | 18 +++++
drivers/gpu/drm/spacemit/Makefile | 12 +++
drivers/gpu/drm/spacemit/spacemit_drm.c | 132 ++++++++++++++++++++++++++++++++
5 files changed, 164 insertions(+)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 323422861e8f..81081562a6da 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -341,6 +341,7 @@ source "drivers/gpu/drm/renesas/Kconfig"
source "drivers/gpu/drm/rockchip/Kconfig"
source "drivers/gpu/drm/sitronix/Kconfig"
source "drivers/gpu/drm/solomon/Kconfig"
+source "drivers/gpu/drm/spacemit/Kconfig"
source "drivers/gpu/drm/sprd/Kconfig"
source "drivers/gpu/drm/sti/Kconfig"
source "drivers/gpu/drm/stm/Kconfig"
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index e97faabcd783..4a105520ee91 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -204,6 +204,7 @@ obj-$(CONFIG_DRM_MSM) += msm/
obj-$(CONFIG_DRM_TEGRA) += tegra/
obj-$(CONFIG_DRM_STM) += stm/
obj-$(CONFIG_DRM_STI) += sti/
+obj-$(CONFIG_DRM_SPACEMIT) += spacemit/
obj-y += imx/
obj-$(CONFIG_DRM_INGENIC) += ingenic/
obj-$(CONFIG_DRM_LOGICVC) += logicvc/
diff --git a/drivers/gpu/drm/spacemit/Kconfig b/drivers/gpu/drm/spacemit/Kconfig
new file mode 100644
index 000000000000..51e38dabfdba
--- /dev/null
+++ b/drivers/gpu/drm/spacemit/Kconfig
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config DRM_SPACEMIT
+ tristate "DRM support for SpacemiT display controllers"
+ depends on DRM && OF && MMU
+ depends on ARCH_SPACEMIT || COMPILE_TEST
+ select DRM_CLIENT_SELECTION
+ select DRM_KMS_HELPER
+ select DRM_GEM_SHMEM_HELPER
+ select REGMAP_MMIO
+ select VIDEOMODE_HELPERS
+ help
+ Choose this option if you have a SpacemiT SoC with the Saturn
+ display processing unit, such as the K3. The DPU scans out
+ framebuffers through its private display MMU and feeds a
+ DisplayPort or embedded DisplayPort controller.
+
+ If M is selected the module will be called spacemit-drm.
diff --git a/drivers/gpu/drm/spacemit/Makefile b/drivers/gpu/drm/spacemit/Makefile
new file mode 100644
index 000000000000..b3b148000cf7
--- /dev/null
+++ b/drivers/gpu/drm/spacemit/Makefile
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+
+spacemit-drm-y := spacemit_drm.o \
+ spacemit_crtc.o \
+ spacemit_cmdlist.o \
+ spacemit_planes.o \
+ spacemit_dmmu.o \
+ dpu/dpu_saturn.o \
+ dpu/dpu_saturn_hee.o \
+ dpu/saturn_fbcmem.o
+
+obj-$(CONFIG_DRM_SPACEMIT) += spacemit-drm.o
diff --git a/drivers/gpu/drm/spacemit/spacemit_drm.c b/drivers/gpu/drm/spacemit/spacemit_drm.c
new file mode 100644
index 000000000000..9fb6a7661b48
--- /dev/null
+++ b/drivers/gpu/drm/spacemit/spacemit_drm.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025-2026 SpacemiT Co., Ltd.
+ *
+ */
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_of.h>
+#include <drm/drm_fbdev_shmem.h>
+#include <linux/component.h>
+#include <linux/of_graph.h>
+
+#include "spacemit_drm.h"
+#include "spacemit_crtc.h"
+
+#define DRIVER_NAME "spacemit"
+#define DRIVER_DESC "SpacemiT SoC DRM driver"
+#define DRIVER_MAJOR 1
+#define DRIVER_MINOR 0
+
+static void spacemit_drm_atomic_commit_tail(struct drm_atomic_commit *old_state)
+{
+ struct drm_device *dev = old_state->dev;
+
+ drm_atomic_helper_commit_modeset_disables(dev, old_state);
+
+ drm_atomic_helper_commit_modeset_enables(dev, old_state);
+
+ drm_atomic_helper_commit_planes(dev, old_state,
+ DRM_PLANE_COMMIT_ACTIVE_ONLY);
+
+ drm_atomic_helper_wait_for_flip_done(dev, old_state);
+
+ drm_atomic_helper_commit_hw_done(old_state);
+
+ drm_atomic_helper_cleanup_planes(dev, old_state);
+}
+
+static const struct drm_mode_config_helper_funcs spacemit_drm_mode_config_helper = {
+ .atomic_commit_tail = spacemit_drm_atomic_commit_tail,
+};
+
+static const struct drm_mode_config_funcs spacemit_drm_mode_config_funcs = {
+ .fb_create = drm_gem_fb_create,
+ .atomic_check = drm_atomic_helper_check,
+ .atomic_commit = drm_atomic_helper_commit,
+};
+
+int spacemit_drm_mode_config_init(struct drm_device *drm)
+{
+ int ret;
+
+ ret = drmm_mode_config_init(drm);
+ if (ret)
+ return ret;
+
+ drm->mode_config.min_width = 1;
+ drm->mode_config.min_height = 1;
+ /* K3 user manual: each DPU scans out at most 3840x2160@60 */
+ drm->mode_config.max_width = 3840;
+ drm->mode_config.max_height = 2160;
+
+ drm->mode_config.funcs = &spacemit_drm_mode_config_funcs;
+ drm->mode_config.helper_private = &spacemit_drm_mode_config_helper;
+
+ return 0;
+}
+
+DEFINE_DRM_GEM_FOPS(spacemit_drm_fops);
+
+struct drm_driver spacemit_drm_drv = {
+ .driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+ .fops = &spacemit_drm_fops,
+
+ DRM_GEM_SHMEM_DRIVER_OPS,
+ DRM_FBDEV_SHMEM_DRIVER_OPS,
+
+ .name = DRIVER_NAME,
+ .desc = DRIVER_DESC,
+ .major = DRIVER_MAJOR,
+ .minor = DRIVER_MINOR,
+};
+
+static int compare_of(struct device *dev, void *data)
+{
+ return dev->of_node == data;
+}
+
+int spacemit_drm_of_component_probe(struct device *dev)
+{
+ struct device_node *ports, *port, *ep;
+ struct device_node *remote;
+ struct component_match *match = NULL;
+
+ if (!dev->of_node)
+ return -EINVAL;
+
+ /* The DPU is the drm root: its OF graph names the DP/eDP components. */
+ ports = of_get_child_by_name(dev->of_node, "ports");
+ if (!ports) {
+ dev_err(dev, "missing 'ports' child node\n");
+ return -EINVAL;
+ }
+
+ for_each_child_of_node(ports, port) {
+ if (!of_node_name_eq(port, "port"))
+ continue;
+ for_each_child_of_node(port, ep) {
+ if (!of_node_name_eq(ep, "endpoint"))
+ continue;
+ remote = of_graph_get_remote_port_parent(ep);
+ if (!remote)
+ continue;
+ if (of_device_is_available(remote))
+ drm_of_component_match_add(dev, &match,
+ compare_of, remote);
+ of_node_put(remote);
+ }
+ }
+ of_node_put(ports);
+
+ if (!match) {
+ dev_err(dev, "no downstream component available\n");
+ return -ENODEV;
+ }
+
+ return component_master_add_with_match(dev, &spacemit_drm_master_ops,
+ match);
+}
--
2.43.0