[PATCH 3/6] drm/panel: dsi-bpf: Add BPF program build infrastructure and helper header

[Maxime Ripard]

Add the BPF-side header panel-bpf-mipi-dsi.h and a standalone
Makefile for building panel BPF programs. The header provides
section name macros (PANEL_BPF_MIPI_DSI_PREPARE, etc.), the
PANEL_BPF_MIPI_DSI_OPS() struct_ops declaration macro, extern
declarations for all the kfuncs, and some convenience macros.

The Makefile follows the same pattern as drivers/hid/bpf/progs/.
It generates vmlinux.h from BTF, bootstraps bpftool and libbpf
from the kernel tools/ directory, then compiles every *.bpf.c
file into a stripped .bpf.o object. The resulting objects are
userspace artifacts loaded at runtime.

Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
---
 drivers/gpu/drm/panel/bpf/progs/Makefile           | 93 +++++++++++++++++++++
 .../gpu/drm/panel/bpf/progs/panel-bpf-mipi-dsi.h   | 95 ++++++++++++++++++++++
 include/drm/drm_panel_dsi_bpf.h                    | 50 ------------
 3 files changed, 188 insertions(+), 50 deletions(-)

diff --git a/drivers/gpu/drm/panel/bpf/progs/Makefile b/drivers/gpu/drm/panel/bpf/progs/Makefile
new file mode 100644
index 000000000000..74190ee618ab
--- /dev/null
+++ b/drivers/gpu/drm/panel/bpf/progs/Makefile
@@ -0,0 +1,93 @@
+# SPDX-License-Identifier: GPL-2.0
+OUTPUT := .output
+abs_out := $(abspath $(OUTPUT))
+
+CLANG ?= clang
+LLC ?= llc
+LLVM_STRIP ?= llvm-strip
+
+TOOLS_PATH := $(abspath ../../../../../../tools)
+BPFTOOL_SRC := $(TOOLS_PATH)/bpf/bpftool
+BPFTOOL_OUTPUT := $(abs_out)/bpftool
+DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)/bootstrap/bpftool
+BPFTOOL ?= $(DEFAULT_BPFTOOL)
+
+LIBBPF_SRC := $(TOOLS_PATH)/lib/bpf
+LIBBPF_OUTPUT := $(abs_out)/libbpf
+LIBBPF_DESTDIR := $(LIBBPF_OUTPUT)
+LIBBPF_INCLUDE := $(LIBBPF_DESTDIR)/include
+BPFOBJ := $(LIBBPF_OUTPUT)/libbpf.a
+
+INCLUDES := -I$(OUTPUT) -I$(LIBBPF_INCLUDE) -I$(TOOLS_PATH)/include/uapi
+CFLAGS := -g -Wall
+
+VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)				\
+		     $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux)	\
+		     ../../../../../../vmlinux				\
+		     /sys/kernel/btf/vmlinux				\
+		     /boot/vmlinux-$(shell uname -r)
+VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
+ifeq ($(VMLINUX_BTF),)
+$(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)")
+endif
+
+ifeq ($(V),1)
+Q =
+msg =
+else
+Q = @
+msg = @printf '  %-8s %s%s\n' "$(1)" "$(notdir $(2))" "$(if $(3), $(3))";
+MAKEFLAGS += --no-print-directory
+submake_extras := feature_display=0
+endif
+
+.DELETE_ON_ERROR:
+
+.PHONY: all clean
+
+SOURCES = $(wildcard *.bpf.c)
+TARGETS = $(SOURCES:.bpf.c=.bpf.o)
+
+all: $(TARGETS)
+
+clean:
+	$(call msg,CLEAN)
+	$(Q)rm -rf $(OUTPUT) $(TARGETS)
+
+%.bpf.o: %.bpf.c vmlinux.h $(BPFOBJ) | $(OUTPUT)
+	$(call msg,BPF,$@)
+	$(Q)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(INCLUDES)		\
+		     -Wno-microsoft-anon-tag					\
+		     -fms-extensions						\
+		     -c $(filter %.c,$^) -o $@ &&				\
+	$(LLVM_STRIP) -g $@
+
+vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR)
+ifeq ($(VMLINUX_H),)
+	$(call msg,GEN,,$@)
+	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
+else
+	$(call msg,CP,,$@)
+	$(Q)cp "$(VMLINUX_H)" $@
+endif
+
+$(OUTPUT) $(LIBBPF_OUTPUT) $(BPFTOOL_OUTPUT):
+	$(call msg,MKDIR,$@)
+	$(Q)mkdir -p $@
+
+$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUTPUT)
+	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)			       \
+		    OUTPUT=$(abspath $(dir $@))/ prefix=		       \
+		    DESTDIR=$(LIBBPF_DESTDIR) $(abspath $@) install_headers
+
+ifeq ($(CROSS_COMPILE),)
+$(DEFAULT_BPFTOOL): $(BPFOBJ) | $(BPFTOOL_OUTPUT)
+	$(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC)			       \
+		    OUTPUT=$(BPFTOOL_OUTPUT)/				       \
+		    LIBBPF_BOOTSTRAP_OUTPUT=$(LIBBPF_OUTPUT)/		       \
+		    LIBBPF_BOOTSTRAP_DESTDIR=$(LIBBPF_DESTDIR)/ bootstrap
+else
+$(DEFAULT_BPFTOOL): | $(BPFTOOL_OUTPUT)
+	$(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC)			       \
+		    OUTPUT=$(BPFTOOL_OUTPUT)/ bootstrap
+endif
diff --git a/drivers/gpu/drm/panel/bpf/progs/panel-bpf-mipi-dsi.h b/drivers/gpu/drm/panel/bpf/progs/panel-bpf-mipi-dsi.h
new file mode 100644
index 000000000000..e2b03afef2c8
--- /dev/null
+++ b/drivers/gpu/drm/panel/bpf/progs/panel-bpf-mipi-dsi.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ____PANEL_BPF_MIPI_DSI_BPF__H
+#define ____PANEL_BPF_MIPI_DSI_BPF__H
+
+#define PANEL_BPF_MIPI_DSI_PREPARE	"struct_ops.s/panel_prepare"
+#define PANEL_BPF_MIPI_DSI_UNPREPARE	"struct_ops.s/panel_unprepare"
+#define PANEL_BPF_MIPI_DSI_ENABLE	"struct_ops.s/panel_enable"
+#define PANEL_BPF_MIPI_DSI_DISABLE	"struct_ops.s/panel_disable"
+
+#define PANEL_BPF_MIPI_DSI_OPS(name) SEC(".struct_ops") \
+	struct drm_panel_dsi_bpf_ops name
+
+/* Mode flags — kernel #defines not exported through BTF */
+#define MIPI_DSI_MODE_VIDEO		(1 << 0)
+#define MIPI_DSI_MODE_VIDEO_BURST	(1 << 1)
+#define MIPI_DSI_MODE_VIDEO_SYNC_PULSE	(1 << 2)
+#define MIPI_DSI_MODE_NO_EOT_PACKET	(1 << 9)
+#define MIPI_DSI_CLOCK_NON_CONTINUOUS	(1 << 10)
+#define MIPI_DSI_MODE_LPM		(1 << 11)
+
+extern int panel_bpf_mipi_dsi_regulator_enable_and_wait(struct panel_bpf_mipi_dsi_ctx *ctx,
+							enum panel_bpf_mipi_dsi_supply supply,
+							__u32 settle_ms) __ksym;
+extern int panel_bpf_mipi_dsi_regulator_disable(struct panel_bpf_mipi_dsi_ctx *ctx,
+						enum panel_bpf_mipi_dsi_supply supply) __ksym;
+extern void panel_bpf_mipi_dsi_gpio_cycle_and_wait(struct panel_bpf_mipi_dsi_ctx *ctx,
+						   enum panel_bpf_mipi_dsi_gpio gpio,
+						   __u32 assert_ms,
+						   __u32 settle_ms) __ksym;
+extern void panel_bpf_mipi_dsi_gpio_enable(struct panel_bpf_mipi_dsi_ctx *ctx,
+					   enum panel_bpf_mipi_dsi_gpio gpio) __ksym;
+extern void panel_bpf_mipi_dsi_gpio_disable(struct panel_bpf_mipi_dsi_ctx *ctx,
+					   enum panel_bpf_mipi_dsi_gpio gpio) __ksym;
+extern int panel_bpf_mipi_dsi_dcs_write_and_wait(struct panel_bpf_mipi_dsi_ctx *ctx,
+						  __u8 cmd, const __u8 *data,
+						  __u32 data__sz,
+						  __u32 settle_ms) __ksym;
+extern int panel_bpf_mipi_dsi_generic_write_and_wait(struct panel_bpf_mipi_dsi_ctx *ctx,
+						     const __u8 *data,
+						     __u32 data__sz,
+						     __u32 settle_ms) __ksym;
+extern int panel_bpf_mipi_dsi_dcs_read(struct panel_bpf_mipi_dsi_ctx *ctx,
+				       __u8 cmd, __u8 *data,
+				       __u32 data__sz) __ksym;
+
+/*
+ * Convenience macros
+ *
+ * These wrap the _and_wait kfuncs with settle_ms = 0 for the common
+ * case where no post-operation delay is needed.
+ */
+
+/* Enable a supply without a post-enable delay. */
+#define panel_bpf_mipi_dsi_regulator_enable(ctx, supply)			\
+	panel_bpf_mipi_dsi_regulator_enable_and_wait((ctx), (supply), 0)
+
+/* Send a DCS command without a post-send delay. */
+#define panel_bpf_mipi_dsi_dcs_write(ctx, cmd, data, data__sz)		\
+	panel_bpf_mipi_dsi_dcs_write_and_wait((ctx), (cmd), (data), (data__sz), 0)
+
+/* Send a generic DSI write without a post-send delay. */
+#define panel_bpf_mipi_dsi_generic_write(ctx, data, data__sz)		\
+	panel_bpf_mipi_dsi_generic_write_and_wait((ctx), (data), (data__sz), 0)
+
+/* Send a DCS command with a single byte payload. */
+#define panel_bpf_mipi_dsi_dcs_write_byte(ctx, cmd, val)		\
+	do {								\
+		const __u8 _v = (val);					\
+		panel_bpf_mipi_dsi_dcs_write((ctx), (cmd), &_v, 1);	\
+	} while (0)
+
+/*
+ * Standard DCS command helpers
+ *
+ * exit_sleep_mode and enter_sleep_mode include the 120ms delay
+ * required by the MIPI DCS specification before the next command.
+ */
+
+/* Send MIPI_DCS_EXIT_SLEEP_MODE with a 120ms settling delay. */
+#define panel_bpf_mipi_dsi_exit_sleep_mode(ctx)				\
+	panel_bpf_mipi_dsi_dcs_write_and_wait((ctx), MIPI_DCS_EXIT_SLEEP_MODE, NULL, 0, 120)
+
+/* Send MIPI_DCS_ENTER_SLEEP_MODE with a 120ms settling delay. */
+#define panel_bpf_mipi_dsi_enter_sleep_mode(ctx)			\
+	panel_bpf_mipi_dsi_dcs_write_and_wait((ctx), MIPI_DCS_ENTER_SLEEP_MODE, NULL, 0, 120)
+
+/* Send MIPI_DCS_SET_DISPLAY_ON. */
+#define panel_bpf_mipi_dsi_set_display_on(ctx)				\
+	panel_bpf_mipi_dsi_dcs_write((ctx), MIPI_DCS_SET_DISPLAY_ON, NULL, 0)
+
+/* Send MIPI_DCS_SET_DISPLAY_OFF. */
+#define panel_bpf_mipi_dsi_set_display_off(ctx)				\
+	panel_bpf_mipi_dsi_dcs_write((ctx), MIPI_DCS_SET_DISPLAY_OFF, NULL, 0)
+
+#endif /* ____PANEL_BPF_MIPI_DSI_BPF__H */
diff --git a/include/drm/drm_panel_dsi_bpf.h b/include/drm/drm_panel_dsi_bpf.h
deleted file mode 100644
index 02d4707fd0a0..000000000000
--- a/include/drm/drm_panel_dsi_bpf.h
+++ /dev/null
@@ -1,50 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __DRM_PANEL_DSI_BPF_H__
-#define __DRM_PANEL_DSI_BPF_H__
-
-#include <linux/bpf.h>
-
-struct mipi_dsi_device;
-struct drm_panel;
-
-#define DSI_BPF_PANEL_ID_LEN	64
-
-/**
- * struct dsi_bpf_ctx - Context passed to BPF panel programs
- * @panel: The drm_panel this callback operates on (private)
- */
-struct dsi_bpf_ctx {
-	struct drm_panel *panel;
-};
-
-/**
- * struct drm_panel_dsi_bpf_ops - BPF struct_ops for MIPI-DSI panels
- * @panel_id: Device identifier for matching. On DT systems this holds
- *	the panel's compatible string. Firmware-agnostic to allow future
- *	ACPI support. Written before load, immutable after.
- * @panel_prepare: Called to power on the panel and send init commands.
- *	Must enable regulators, toggle GPIOs, and send the DSI init
- *	sequence. Sleepable.
- * @panel_unprepare: Called to power off the panel. Must send shutdown
- *	commands, assert reset, and disable regulators. Sleepable.
- * @panel_enable: Optional. Called after video stream starts, for panels
- *	that need post-video-start DSI commands. Sleepable.
- * @panel_disable: Optional. Called before video stream stops. Sleepable.
- * @set_brightness: Optional. Called to set backlight brightness via DSI
- *	commands. Sleepable.
- */
-struct drm_panel_dsi_bpf_ops {
-	char			panel_id[DSI_BPF_PANEL_ID_LEN];
-
-	/* private: internal bookkeeping */
-	struct drm_panel	*panel;
-
-	/* public: */
-	int (*panel_prepare)(struct dsi_bpf_ctx *ctx);
-	int (*panel_unprepare)(struct dsi_bpf_ctx *ctx);
-	int (*panel_enable)(struct dsi_bpf_ctx *ctx);
-	int (*panel_disable)(struct dsi_bpf_ctx *ctx);
-	int (*set_brightness)(struct dsi_bpf_ctx *ctx, u32 brightness);
-};
-
-#endif /* __DRM_PANEL_DSI_BPF_H__ */

-- 
2.55.0