davinci: power: Scan input devices for eligible DT2W node

It is no longer a surprise for anyone to see Xiaomi shipping the same
device with different displays and different displays usually mean
different touchscreen drivers.

The current double tap handling in the power HAL only takes into
account one specific node, meant to be set in the device tree.
However, if the touchscreen was registered as a different input device
it would cause the feature to be broken. Address the issue by iterating
through the input devices in order to find one supported touchscreen
input to be used.

Co-authored-by: LuK1337 <priv.luk@gmail.com>
Change-Id: I2f7fb4a8b0c9cd1a16d6c2b93602d285a191f170

power/power-feature.c

@@ -14,7 +14,9 @@
  * limitations under the License.
  */
 
+#include <dirent.h>
 #include <fcntl.h>
+#include <string.h>
 #include <unistd.h>
 
 #include "power-feature.h"
@@ -23,10 +25,47 @@
 #include <linux/input.h>
 #include <log/log.h>
 
+int open_ts_input() {
+    int fd = -1;
+    DIR *dir = opendir("/dev/input");
+
+    if (dir != NULL) {
+        struct dirent *ent;
+
+        while ((ent = readdir(dir)) != NULL) {
+            if (ent->d_type == DT_CHR) {
+                char absolute_path[PATH_MAX] = {0};
+                char name[80] = {0};
+
+                strcpy(absolute_path, "/dev/input/");
+                strcat(absolute_path, ent->d_name);
+
+                fd = open(absolute_path, O_RDWR);
+                if (ioctl(fd, EVIOCGNAME(sizeof(name) - 1), &name) > 0) {
+                    if (strcmp(name, "fts_ts") == 0 || strcmp(name, "goodix_ts") == 0 ||
+                            strcmp(name, "NVTCapacitiveTouchScreen") == 0)
+                        break;
+                }
+
+                close(fd);
+                fd = -1;
+            }
+        }
+
+        closedir(dir);
+    }
+
+    return fd;
+}
+
 void set_device_specific_feature(feature_t feature, int state) {
     switch (feature) {
         case POWER_FEATURE_DOUBLE_TAP_TO_WAKE: {
-            int fd = open(TAP_TO_WAKE_EVENT_NODE, O_WRONLY);
+            int fd = open_ts_input();
+            if (fd == -1) {
+                ALOGW("DT2W won't work because no supported touchscreen input devices were found");
+                return;
+            }
             struct input_event ev;
             ev.type = EV_SYN;
             ev.code = SYN_CONFIG;

power/power-feature.h

@@ -16,7 +16,5 @@
 
 #define LOG_TAG "libpower_feature.davinci"
 
-#define TAP_TO_WAKE_EVENT_NODE "/dev/input/event2"
-
 #define INPUT_EVENT_WAKUP_MODE_OFF 4
 #define INPUT_EVENT_WAKUP_MODE_ON 5