1 files changed, 174 insertions, 0 deletions

diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
new file mode 100644
index 000000000000..5e44b20b1848
--- /dev/null
+++ b/Documentation/laptops/freefall.c
@@ -0,0 +1,174 @@
+/* Disk protection for HP/DELL machines.
+ *
+ * Copyright 2008 Eric Piel
+ * Copyright 2009 Pavel Machek <pavel@ucw.cz>
+ * Copyright 2012 Sonal Santan
+ * Copyright 2014 Pali Rohár <pali.rohar@gmail.com>
+ *
+ * GPLv2.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <string.h>
+#include <stdint.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <sched.h>
+#include <syslog.h>
+
+static int noled;
+static char unload_heads_path[64];
+static char device_path[32];
+static const char app_name[] = "FREE FALL";
+
+static int set_unload_heads_path(char *device)
+{
+        if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
+                return -EINVAL;
+        strncpy(device_path, device, sizeof(device_path) - 1);
+
+        snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
+                                "/sys/block/%s/device/unload_heads", device+5);
+        return 0;
+}
+
+static int valid_disk(void)
+{
+        int fd = open(unload_heads_path, O_RDONLY);
+
+        if (fd < 0) {
+                perror(unload_heads_path);
+                return 0;
+        }
+
+        close(fd);
+        return 1;
+}
+
+static void write_int(char *path, int i)
+{
+        char buf[1024];
+        int fd = open(path, O_RDWR);
+
+        if (fd < 0) {
+                perror("open");
+                exit(1);
+        }
+
+        sprintf(buf, "%d", i);
+
+        if (write(fd, buf, strlen(buf)) != strlen(buf)) {
+                perror("write");
+                exit(1);
+        }
+
+        close(fd);
+}
+
+static void set_led(int on)
+{
+        if (noled)
+                return;
+        write_int("/sys/class/leds/hp::hddprotect/brightness", on);
+}
+
+static void protect(int seconds)
+{
+        const char *str = (seconds == 0) ? "Unparked" : "Parked";
+
+        write_int(unload_heads_path, seconds*1000);
+        syslog(LOG_INFO, "%s %s disk head\n", str, device_path);
+}
+
+static int on_ac(void)
+{
+        /* /sys/class/power_supply/AC0/online */
+        return 1;
+}
+
+static int lid_open(void)
+{
+        /* /proc/acpi/button/lid/LID/state */
+        return 1;
+}
+
+static void ignore_me(int signum)
+{
+        protect(0);
+        set_led(0);
+}
+
+int main(int argc, char **argv)
+{
+        int fd, ret;
+        struct stat st;
+        struct sched_param param;
+
+        if (argc == 1)
+                ret = set_unload_heads_path("/dev/sda");
+        else if (argc == 2)
+                ret = set_unload_heads_path(argv[1]);
+        else
+                ret = -EINVAL;
+
+        if (ret || !valid_disk()) {
+                fprintf(stderr, "usage: %s <device> (default: /dev/sda)\n",
+                                argv[0]);
+                exit(1);
+        }
+
+        fd = open("/dev/freefall", O_RDONLY);
+        if (fd < 0) {
+                perror("/dev/freefall");
+                return EXIT_FAILURE;
+        }
+
+        if (stat("/sys/class/leds/hp::hddprotect/brightness", &st))
+                noled = 1;
+
+        if (daemon(0, 0) != 0) {
+                perror("daemon");
+                return EXIT_FAILURE;
+        }
+
+        openlog(app_name, LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);
+
+        param.sched_priority = sched_get_priority_max(SCHED_FIFO);
+        sched_setscheduler(0, SCHED_FIFO, &param);
+        mlockall(MCL_CURRENT|MCL_FUTURE);
+
+        signal(SIGALRM, ignore_me);
+
+        for (;;) {
+                unsigned char count;
+
+                ret = read(fd, &count, sizeof(count));
+                alarm(0);
+                if ((ret == -1) && (errno == EINTR)) {
+                        /* Alarm expired, time to unpark the heads */
+                        continue;
+                }
+
+                if (ret != sizeof(count)) {
+                        perror("read");
+                        break;
+                }
+
+                protect(21);
+                set_led(1);
+                if (1 || on_ac() || lid_open())
+                        alarm(2);
+                else
+                        alarm(20);
+        }
+
+        closelog();
+        close(fd);
+        return EXIT_SUCCESS;
+}