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-rw-r--r--samples/hid/hid_surface_dial.c226
1 files changed, 226 insertions, 0 deletions
diff --git a/samples/hid/hid_surface_dial.c b/samples/hid/hid_surface_dial.c
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+++ b/samples/hid/hid_surface_dial.c
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+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2022 Benjamin Tissoires
+ *
+ * This program will morph the Microsoft Surface Dial into a mouse,
+ * and depending on the chosen resolution enable or not the haptic feedback:
+ * - a resolution (-r) of 3600 will report 3600 "ticks" in one full rotation
+ * without haptic feedback
+ * - any other resolution will report N "ticks" in a full rotation with haptic
+ * feedback
+ *
+ * A good default for low resolution haptic scrolling is 72 (1 "tick" every 5
+ * degrees), and set to 3600 for smooth scrolling.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <unistd.h>
+
+#include <linux/bpf.h>
+#include <linux/errno.h>
+
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "hid_surface_dial.skel.h"
+#include "hid_bpf_attach.h"
+
+static bool running = true;
+
+struct haptic_syscall_args {
+ unsigned int hid;
+ int retval;
+};
+
+static void int_exit(int sig)
+{
+ running = false;
+ exit(0);
+}
+
+static void usage(const char *prog)
+{
+ fprintf(stderr,
+ "%s: %s [OPTIONS] /sys/bus/hid/devices/0BUS:0VID:0PID:00ID\n\n"
+ " OPTIONS:\n"
+ " -r N\t set the given resolution to the device (number of ticks per 360°)\n\n",
+ __func__, prog);
+ fprintf(stderr,
+ "This program will morph the Microsoft Surface Dial into a mouse,\n"
+ "and depending on the chosen resolution enable or not the haptic feedback:\n"
+ "- a resolution (-r) of 3600 will report 3600 'ticks' in one full rotation\n"
+ " without haptic feedback\n"
+ "- any other resolution will report N 'ticks' in a full rotation with haptic\n"
+ " feedback\n"
+ "\n"
+ "A good default for low resolution haptic scrolling is 72 (1 'tick' every 5\n"
+ "degrees), and set to 3600 for smooth scrolling.\n");
+}
+
+static int get_hid_id(const char *path)
+{
+ const char *str_id, *dir;
+ char uevent[1024];
+ int fd;
+
+ memset(uevent, 0, sizeof(uevent));
+ snprintf(uevent, sizeof(uevent) - 1, "%s/uevent", path);
+
+ fd = open(uevent, O_RDONLY | O_NONBLOCK);
+ if (fd < 0)
+ return -ENOENT;
+
+ close(fd);
+
+ dir = basename((char *)path);
+
+ str_id = dir + sizeof("0003:0001:0A37.");
+ return (int)strtol(str_id, NULL, 16);
+}
+
+static int attach_prog(struct hid_surface_dial *skel, struct bpf_program *prog, int hid_id)
+{
+ struct attach_prog_args args = {
+ .hid = hid_id,
+ .retval = -1,
+ };
+ int attach_fd, err;
+ DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
+ .ctx_in = &args,
+ .ctx_size_in = sizeof(args),
+ );
+
+ attach_fd = bpf_program__fd(skel->progs.attach_prog);
+ if (attach_fd < 0) {
+ fprintf(stderr, "can't locate attach prog: %m\n");
+ return 1;
+ }
+
+ args.prog_fd = bpf_program__fd(prog);
+ err = bpf_prog_test_run_opts(attach_fd, &tattr);
+ if (err) {
+ fprintf(stderr, "can't attach prog to hid device %d: %m (err: %d)\n",
+ hid_id, err);
+ return 1;
+ }
+ return 0;
+}
+
+static int set_haptic(struct hid_surface_dial *skel, int hid_id)
+{
+ struct haptic_syscall_args args = {
+ .hid = hid_id,
+ .retval = -1,
+ };
+ int haptic_fd, err;
+ DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
+ .ctx_in = &args,
+ .ctx_size_in = sizeof(args),
+ );
+
+ haptic_fd = bpf_program__fd(skel->progs.set_haptic);
+ if (haptic_fd < 0) {
+ fprintf(stderr, "can't locate haptic prog: %m\n");
+ return 1;
+ }
+
+ err = bpf_prog_test_run_opts(haptic_fd, &tattr);
+ if (err) {
+ fprintf(stderr, "can't set haptic configuration to hid device %d: %m (err: %d)\n",
+ hid_id, err);
+ return 1;
+ }
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ struct hid_surface_dial *skel;
+ struct bpf_program *prog;
+ const char *optstr = "r:";
+ const char *sysfs_path;
+ int opt, hid_id, resolution = 72;
+
+ while ((opt = getopt(argc, argv, optstr)) != -1) {
+ switch (opt) {
+ case 'r':
+ {
+ char *endp = NULL;
+ long l = -1;
+
+ if (optarg) {
+ l = strtol(optarg, &endp, 10);
+ if (endp && *endp)
+ l = -1;
+ }
+
+ if (l < 0) {
+ fprintf(stderr,
+ "invalid r option %s - expecting a number\n",
+ optarg ? optarg : "");
+ exit(EXIT_FAILURE);
+ };
+
+ resolution = (int) l;
+ break;
+ }
+ default:
+ usage(basename(argv[0]));
+ return 1;
+ }
+ }
+
+ if (optind == argc) {
+ usage(basename(argv[0]));
+ return 1;
+ }
+
+ sysfs_path = argv[optind];
+ if (!sysfs_path) {
+ perror("sysfs");
+ return 1;
+ }
+
+ skel = hid_surface_dial__open_and_load();
+ if (!skel) {
+ fprintf(stderr, "%s %s:%d", __func__, __FILE__, __LINE__);
+ return -1;
+ }
+
+ hid_id = get_hid_id(sysfs_path);
+ if (hid_id < 0) {
+ fprintf(stderr, "can not open HID device: %m\n");
+ return 1;
+ }
+
+ skel->data->resolution = resolution;
+ skel->data->physical = (int)(resolution / 72);
+
+ bpf_object__for_each_program(prog, *skel->skeleton->obj) {
+ /* ignore syscalls */
+ if (bpf_program__get_type(prog) != BPF_PROG_TYPE_TRACING)
+ continue;
+
+ attach_prog(skel, prog, hid_id);
+ }
+
+ signal(SIGINT, int_exit);
+ signal(SIGTERM, int_exit);
+
+ set_haptic(skel, hid_id);
+
+ while (running)
+ sleep(1);
+
+ hid_surface_dial__destroy(skel);
+
+ return 0;
+}