samples/hid: add Surface Dial example

Add a more complete HID-BPF example.

Signed-off-by: Benjamin Tissoires <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

Author: bentiss

samples/hid/.gitignore

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 hid_mouse
+hid_surface_dial
 *.out
 *.skel.h
 /vmlinux.h

samples/hid/Makefile

@@ -7,6 +7,7 @@ pound := \#
 
 # List of programs to build
 tprogs-y += hid_mouse
+tprogs-y += hid_surface_dial
 
 # Libbpf dependencies
 LIBBPF_SRC = $(TOOLS_PATH)/lib/bpf
@@ -19,6 +20,7 @@ EXTRA_HEADERS := hid_bpf_attach.h
 EXTRA_BPF_HEADERS := hid_bpf_helpers.h
 
 hid_mouse-objs := hid_mouse.o
+hid_surface_dial-objs := hid_surface_dial.o
 
 # Tell kbuild to always build the programs
 always-y := $(tprogs-y)
@@ -156,6 +158,7 @@ libbpf_hdrs: $(LIBBPF)
 .PHONY: libbpf_hdrs
 
 $(obj)/hid_mouse.o: $(obj)/hid_mouse.skel.h
+$(obj)/hid_surface_dial.o: $(obj)/hid_surface_dial.skel.h
 
 -include $(HID_SAMPLES_PATH)/Makefile.target
 
@@ -201,10 +204,11 @@ $(obj)/%.bpf.o: $(src)/%.bpf.c $(EXTRA_BPF_HEADERS_SRC) $(obj)/vmlinux.h
 		-I$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES) \
 		-c $(filter %.bpf.c,$^) -o $@
 
-LINKED_SKELS := hid_mouse.skel.h
+LINKED_SKELS := hid_mouse.skel.h hid_surface_dial.skel.h
 clean-files += $(LINKED_SKELS)
 
 hid_mouse.skel.h-deps := hid_mouse.bpf.o hid_bpf_attach.bpf.o
+hid_surface_dial.skel.h-deps := hid_surface_dial.bpf.o hid_bpf_attach.bpf.o
 
 LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.bpf.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 

samples/hid/hid_bpf_helpers.h

@@ -10,6 +10,8 @@ extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx,
 			      unsigned int offset,
 			      const size_t __sz) __ksym;
 extern int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, u32 flags) __ksym;
+extern struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id) __ksym;
+extern void hid_bpf_release_context(struct hid_bpf_ctx *ctx) __ksym;
 extern int hid_bpf_hw_request(struct hid_bpf_ctx *ctx,
 			      __u8 *data,
 			      size_t buf__sz,

samples/hid/hid_surface_dial.bpf.c

@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2022 Benjamin Tissoires
+ */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "hid_bpf_helpers.h"
+
+#define HID_UP_BUTTON		0x0009
+#define HID_GD_WHEEL		0x0038
+
+SEC("fmod_ret/hid_bpf_device_event")
+int BPF_PROG(hid_event, struct hid_bpf_ctx *hctx)
+{
+	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
+
+	if (!data)
+		return 0; /* EPERM check */
+
+	/* Touch */
+	data[1] &= 0xfd;
+
+	/* X */
+	data[4] = 0;
+	data[5] = 0;
+
+	/* Y */
+	data[6] = 0;
+	data[7] = 0;
+
+	return 0;
+}
+
+/* 72 == 360 / 5 -> 1 report every 5 degrees */
+int resolution = 72;
+int physical = 5;
+
+struct haptic_syscall_args {
+	unsigned int hid;
+	int retval;
+};
+
+static __u8 haptic_data[8];
+
+SEC("syscall")
+int set_haptic(struct haptic_syscall_args *args)
+{
+	struct hid_bpf_ctx *ctx;
+	const size_t size = sizeof(haptic_data);
+	u16 *res;
+	int ret;
+
+	if (size > sizeof(haptic_data))
+		return -7; /* -E2BIG */
+
+	ctx = hid_bpf_allocate_context(args->hid);
+	if (!ctx)
+		return -1; /* EPERM check */
+
+	haptic_data[0] = 1;  /* report ID */
+
+	ret = hid_bpf_hw_request(ctx, haptic_data, size, HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
+
+	bpf_printk("probed/remove event ret value: %d", ret);
+	bpf_printk("buf: %02x %02x %02x",
+		   haptic_data[0],
+		   haptic_data[1],
+		   haptic_data[2]);
+	bpf_printk("     %02x %02x %02x",
+		   haptic_data[3],
+		   haptic_data[4],
+		   haptic_data[5]);
+	bpf_printk("     %02x %02x",
+		   haptic_data[6],
+		   haptic_data[7]);
+
+	/* whenever resolution multiplier is not 3600, we have the fixed report descriptor */
+	res = (u16 *)&haptic_data[1];
+	if (*res != 3600) {
+//		haptic_data[1] = 72; /* resolution multiplier */
+//		haptic_data[2] = 0;  /* resolution multiplier */
+//		haptic_data[3] = 0;  /* Repeat Count */
+		haptic_data[4] = 3;  /* haptic Auto Trigger */
+//		haptic_data[5] = 5;  /* Waveform Cutoff Time */
+//		haptic_data[6] = 80; /* Retrigger Period */
+//		haptic_data[7] = 0;  /* Retrigger Period */
+	} else {
+		haptic_data[4] = 0;
+	}
+
+	ret = hid_bpf_hw_request(ctx, haptic_data, size, HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
+
+	bpf_printk("set haptic ret value: %d -> %d", ret, haptic_data[4]);
+
+	args->retval = ret;
+
+	hid_bpf_release_context(ctx);
+
+	return 0;
+}
+
+/* Convert REL_DIAL into REL_WHEEL */
+SEC("fmod_ret/hid_bpf_rdesc_fixup")
+int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
+{
+	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
+	__u16 *res, *phys;
+
+	if (!data)
+		return 0; /* EPERM check */
+
+	/* Convert TOUCH into a button */
+	data[31] = HID_UP_BUTTON;
+	data[33] = 2;
+
+	/* Convert REL_DIAL into REL_WHEEL */
+	data[45] = HID_GD_WHEEL;
+
+	/* Change Resolution Multiplier */
+	phys = (__u16 *)&data[61];
+	*phys = physical;
+	res = (__u16 *)&data[66];
+	*res = resolution;
+
+	/* Convert X,Y from Abs to Rel */
+	data[88] = 0x06;
+	data[98] = 0x06;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = 1;