mapping single-key input devices to buttons

[Johannes Berg]

After some discussion on IRC I came up with the following patch.

I *don't* understand why any input devices get a 'button' capability,
and this isn't addressed by my patch. If that capability is removed (I
wouldn't have expected it to be present after discussing this with
davidz), then the check_btn routine needs to add it. It should also
probably handle more types of buttons...

In any case, this patch fixes an issue with test_bit -- a kernel
compatible implementation should be used or junk ensues.

Signed-off-by: Johannes Berg <johannes at sipsolutions.net>

--- a/hal/hald/linux2/probing/probe-input.c
+++ b/hal/hald/linux2/probing/probe-input.c
@@ -42,13 +42,19 @@
 
 #include "shared.h"
 
-#define test_bit(bit, array) (array[(bit) / 8] & (1 << ((bit) % 8)))
+/* we must use this kernel-compatible implementation */
+#define BITS_PER_LONG (sizeof(long) * 8)
+#define NBITS(x) ((((x)-1)/BITS_PER_LONG)+1)
+#define OFF(x)  ((x)%BITS_PER_LONG)
+#define BIT(x)  (1UL<<OFF(x))
+#define LONG(x) ((x)/BITS_PER_LONG)
+#define test_bit(bit, array)    ((array[LONG(bit)] >> OFF(bit)) & 1)
 
 static void 
 check_abs (int fd, LibHalContext *ctx, const char *udi)
 {
-	char bitmask[(ABS_MAX + 7) / 8];
-	char bitmask_touch[(KEY_MAX + 7) / 8];
+	long bitmask[NBITS(ABS_MAX)];
+	long bitmask_touch[NBITS(KEY_MAX)];
 	DBusError error;
 
 	if (ioctl (fd, EVIOCGBIT(EV_ABS, sizeof (bitmask)), bitmask) < 0) {
@@ -81,7 +87,7 @@
 check_key (int fd, LibHalContext *ctx, const char *udi)
 {
 	unsigned int i;
-	char bitmask[(KEY_MAX + 7) / 8];
+	long bitmask[NBITS(KEY_MAX)];
 	int is_keyboard;
 	DBusError error;
 
@@ -112,7 +118,7 @@
 static void 
 check_rel (int fd, LibHalContext *ctx, const char *udi)
 {
-	char bitmask[(REL_MAX + 7) / 8];
+	long bitmask[NBITS(REL_MAX)];
 	DBusError error;
 
 	if (ioctl (fd, EVIOCGBIT(EV_REL, sizeof (bitmask)), bitmask) < 0) {
@@ -132,6 +138,43 @@
 	;
 }
 
+static void 
+check_btn (int fd, LibHalContext *ctx, const char *udi)
+{
+	unsigned int i;
+	long bitmask[NBITS(KEY_MAX)];
+	int buttons = 0, button = KEY_RESERVED;
+	DBusError error;
+
+	if (ioctl (fd, EVIOCGBIT(EV_KEY, sizeof (bitmask)), bitmask) < 0) {
+		fprintf(stderr, "ioctl EVIOCGBIT failed\n");
+		goto out;
+	}
+
+	/* All devices that have just a single button... */
+	for (i = KEY_RESERVED + 1; i < KEY_MAX; i++) {
+		if (test_bit (i, bitmask)) {
+			buttons++;
+			button = i;
+			break;
+		}
+	}
+	if (buttons == 1) {
+		dbus_error_init (&error);
+		switch (button) {
+		case KEY_POWER:
+			libhal_device_property_strlist_append (ctx, udi, "button.type", "power", &error);
+			break;
+		case KEY_EJECTCD:
+			libhal_device_property_strlist_append (ctx, udi, "button.type", "eject-cd", &error);
+			break;
+		}
+	}
+
+out:
+	;
+}
+
 int 
 main (int argc, char *argv[])
 {
@@ -189,6 +232,7 @@
 		case 17: /* TODO: x86 legacy port; use symbol instead of hardcoded constant */
 		case 21: /* BUS_HOST, not hotpluggable */
 		case 23: /* ADB on Apple computers */
+		case 32: /* PMU on Apple computers (unmerged as of now) */
 			break;
 		default:
 			goto out;
@@ -208,6 +252,7 @@
 	check_abs (fd, ctx, udi);
 	check_rel (fd, ctx, udi);
 	check_key (fd, ctx, udi);
+	check_btn (fd, ctx, udi);
 
 	/* success */
 	ret = 0;