liblights: Expose panel brightness in helper lib
Change-Id: I810166818eac84466dfe2c4b88dff47e83a181c0
diff --git a/liblights/lights_helper.c b/liblights/lights_helper.c
new file mode 100644
index 0000000..c3406ab
--- /dev/null
+++ b/liblights/lights_helper.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2016 The CyanogenMod Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <cutils/log.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <liblights/samsung_lights_helper.h>
+
+/*
+ * Reads an Integer from a file.
+ *
+ * @param path The absolute path string.
+ * @return The Integer with decimal base, -1 on error.
+ */
+int read_int(char const *path)
+{
+ int fd, len;
+ int num_bytes = 10;
+ char buf[11];
+ int retval;
+
+ fd = open(path, O_RDONLY);
+ if (fd < 0) {
+ ALOGE("%s: failed to open %s\n", __func__, path);
+ goto fail;
+ }
+
+ len = read(fd, buf, num_bytes - 1);
+ if (len < 0) {
+ ALOGE("%s: failed to read from %s\n", __func__, path);
+ goto fail;
+ }
+
+ buf[len] = '\0';
+ close(fd);
+
+ // no endptr, decimal base
+ retval = strtol(buf, NULL, 10);
+ return retval == 0 ? -1 : retval;
+
+fail:
+ if (fd >= 0)
+ close(fd);
+ return -1;
+}
+
+/*
+ * Writes an Integer to a file.
+ *
+ * @param path The absolute path string.
+ * @param value The Integer value to be written.
+ * @return 0 on success, -1 or errno on error.
+ */
+int write_int(char const *path, const int value)
+{
+ int fd;
+ static int already_warned;
+
+ already_warned = 0;
+
+ ALOGV("write_int: path %s, value %d", path, value);
+ fd = open(path, O_RDWR);
+
+ if (fd >= 0) {
+ char buffer[20];
+ int bytes = sprintf(buffer, "%d\n", value);
+ int amt = write(fd, buffer, bytes);
+ close(fd);
+ return amt == -1 ? -errno : 0;
+ } else {
+ if (already_warned == 0) {
+ ALOGE("write_int failed to open %s\n", path);
+ already_warned = 1;
+ }
+ return -errno;
+ }
+}
+
+/*
+ * Set the current button brightness via sysfs.
+ *
+ * @param brightness The brightness value.
+ * @return 0 on success, -1 or errno on error.
+ */
+inline int set_cur_button_brightness(const int brightness)
+{
+ return write_int(BUTTON_BRIGHTNESS_NODE, brightness);
+}
+
+/*
+ * Read the current panel brightness from sysfs.
+ *
+ * @return The brightness as Integer, -1 on error.
+ */
+inline int get_cur_panel_brightness()
+{
+ return read_int(PANEL_BRIGHTNESS_NODE);
+}
+
+/*
+ * Read the maximum panel brightness from sysfs.
+ *
+ * @return The brightness as Integer, -1 on error.
+ */
+inline int get_max_panel_brightness()
+{
+ return read_int(PANEL_MAX_BRIGHTNESS_NODE);
+}
+
+/*
+ * Set the current panel brightness via sysfs.
+ *
+ * @param brightness The (scaled) brightness value.
+ * @return 0 on success, -1 or errno on error.
+ */
+inline int set_cur_panel_brightness(const int brightness)
+{
+ return write_int(PANEL_BRIGHTNESS_NODE, brightness);
+}
+
+/*
+ * Set the maximum panel brightness via sysfs.
+ *
+ * @param brightness The brightness value.
+ * @return 0 on success, -1 or errno on error.
+ */
+inline int set_max_panel_brightness(const int brightness)
+{
+ return write_int(PANEL_MAX_BRIGHTNESS_NODE, brightness);
+}