1 files changed, 309 insertions, 0 deletions
diff --git a/src/libbacklight.c b/src/libbacklight.c
new file mode 100644
index 00000000..b3acc63f
--- /dev/null
+++ b/src/libbacklight.c
@@ -0,0 +1,309 @@
+/*
+ * libbacklight - userspace interface to Linux backlight control
+ *
+ * Copyright © 2012 Intel Corporation
+ * Copyright 2010 Red Hat <mjg@redhat.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Matthew Garrett <mjg@redhat.com>
+ *    Tiago Vignatti <vignatti@freedesktop.org>
+ */
+
+#include "config.h"
+
+#include "libbacklight.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <linux/types.h>
+#include <dirent.h>
+#include <drm.h>
+#include <fcntl.h>
+#include <malloc.h>
+#include <string.h>
+#include <errno.h>
+
+static long backlight_get(struct backlight *backlight, char *node)
+{
+	char buffer[100];
+	char *path;
+	int fd;
+	long value, ret;
+
+	if (asprintf(&path, "%s/%s", backlight->path, node) < 0)
+		return -ENOMEM
+;
+	fd = open(path, O_RDONLY);
+	if (fd < 0) {
+		ret = -1;
+		goto out;
+	}
+
+	ret = read(fd, &buffer, sizeof(buffer));
+	if (ret < 1) {
+		ret = -1;
+		goto out;
+	}
+
+	value = strtol(buffer, NULL, 10);
+	ret = value;
+out:
+	if (fd >= 0)
+		close(fd);
+	free(path);
+	return ret;
+}
+
+long backlight_get_brightness(struct backlight *backlight)
+{
+	return backlight_get(backlight, "brightness");
+}
+
+long backlight_get_max_brightness(struct backlight *backlight)
+{
+	return backlight_get(backlight, "max_brightness");
+}
+
+long backlight_get_actual_brightness(struct backlight *backlight)
+{
+	return backlight_get(backlight, "actual_brightness");
+}
+
+long backlight_set_brightness(struct backlight *backlight, long brightness)
+{
+	char *path;
+	char *buffer = NULL;
+	int fd;
+	long ret;
+
+	if (asprintf(&path, "%s/%s", backlight->path, "brightness") < 0)
+		return -ENOMEM;
+
+	fd = open(path, O_RDWR);
+	if (fd < 0) {
+		ret = -1;
+		goto out;
+	}
+
+	ret = read(fd, &buffer, sizeof(buffer));
+	if (ret < 1) {
+		ret = -1;
+		goto out;
+	}
+
+	if (asprintf(&buffer, "%ld", brightness) < 0) {
+		ret = -1;
+		goto out;
+	}
+
+	ret = write(fd, buffer, strlen(buffer));
+	if (ret < 0) {
+		ret = -1;
+		goto out;
+	}
+
+	ret = backlight_get_brightness(backlight);
+	backlight->brightness = ret;
+out:
+	free(buffer);
+	free(path);
+	if (fd >= 0)
+		close(fd);
+	return ret;
+}
+
+void backlight_destroy(struct backlight *backlight)
+{
+	if (!backlight)
+		return;
+
+	if (backlight->path)
+		free(backlight->path);
+
+	free(backlight);
+}
+
+struct backlight *backlight_init(struct udev_device *drm_device,
+				 uint32_t connector_type)
+{
+	const char *syspath = NULL;
+	char *pci_name = NULL;
+	char *chosen_path = NULL;
+	char *path = NULL;
+	DIR *backlights = NULL;
+	struct dirent *entry;
+	enum backlight_type type = 0;
+	char buffer[100];
+	struct backlight *backlight = NULL;
+	int ret;
+
+	if (!drm_device)
+		return NULL;
+
+	syspath = udev_device_get_syspath(drm_device);
+	if (!syspath)
+		return NULL;
+
+	if (asprintf(&path, "%s/%s", syspath, "device") < 0)
+		return NULL;
+
+	ret = readlink(path, buffer, sizeof(buffer) - 1);
+	free(path);
+	if (ret < 0)
+		return NULL;
+
+	buffer[ret] = '\0';
+	pci_name = basename(buffer);
+
+	if (connector_type <= 0)
+		return NULL;
+
+	backlights = opendir("/sys/class/backlight");
+	if (!backlights)
+		return NULL;
+
+	/* Find the "best" backlight for the device. Firmware
+	   interfaces are preferred over platform interfaces are
+	   preferred over raw interfaces. For raw interfaces we'll
+	   check if the device ID in the form of pci match, while
+	   for firmware interfaces we require the pci ID to
+	   match. It's assumed that platform interfaces always match,
+	   since we can't actually associate them with IDs.
+
+	   A further awkwardness is that, while it's theoretically
+	   possible for an ACPI interface to include support for
+	   changing the backlight of external devices, it's unlikely
+	   to ever be done. It's effectively impossible for a platform
+	   interface to do so. So if we get asked about anything that
+	   isn't LVDS or eDP, we pretty much have to require that the
+	   control be supplied via a raw interface */
+
+	while ((entry = readdir(backlights))) {
+		char *backlight_path;
+		char *parent;
+		enum backlight_type entry_type;
+		int fd;
+
+		if (entry->d_name[0] == '.')
+			continue;
+
+		if (asprintf(&backlight_path, "%s/%s", "/sys/class/backlight",
+			     entry->d_name) < 0)
+			goto err;
+
+		if (asprintf(&path, "%s/%s", backlight_path, "type") < 0)
+			goto err;
+
+		fd = open(path, O_RDONLY);
+
+		if (fd < 0)
+			goto out;
+
+		ret = read (fd, &buffer, sizeof(buffer));
+		close (fd);
+
+		if (ret < 1)
+			goto out;
+
+		buffer[ret] = '\0';
+
+		if (!strncmp(buffer, "raw\n", sizeof(buffer)))
+			entry_type = BACKLIGHT_RAW;
+		else if (!strncmp(buffer, "platform\n", sizeof(buffer)))
+			entry_type = BACKLIGHT_PLATFORM;
+		else if (!strncmp(buffer, "firmware\n", sizeof(buffer)))
+			entry_type = BACKLIGHT_FIRMWARE;
+		else
+			goto out;
+
+		if (connector_type != DRM_MODE_CONNECTOR_LVDS &&
+		    connector_type != DRM_MODE_CONNECTOR_eDP) {
+			/* External displays are assumed to require
+			   gpu control at the moment */
+			if (entry_type != BACKLIGHT_RAW)
+				goto out;
+		}
+
+		free (path);
+
+		if (asprintf(&path, "%s/%s", backlight_path, "device") < 0)
+			goto err;
+
+		ret = readlink(path, buffer, sizeof(buffer) - 1);
+
+		if (ret < 0)
+			goto out;
+
+		buffer[ret] = '\0';
+
+		parent = basename(buffer);
+
+		/* Perform matching for raw and firmware backlights - 
+		   platform backlights have to be assumed to match */
+		if (entry_type == BACKLIGHT_RAW ||
+		    entry_type == BACKLIGHT_FIRMWARE) {
+			if (!(pci_name && !strcmp(pci_name, parent)))
+				goto out;
+		}
+
+		if (entry_type < type)
+			goto out;
+
+		type = entry_type;
+
+		if (chosen_path)
+			free(chosen_path);
+		chosen_path = strdup(backlight_path);
+
+	out:
+		free(backlight_path);
+		free(path);
+	}
+
+	if (!chosen_path)
+		goto err;
+
+	backlight = malloc(sizeof(struct backlight));
+
+	if (!backlight)
+		goto err;
+
+	backlight->path = chosen_path;
+	backlight->type = type;
+
+	backlight->max_brightness = backlight_get_max_brightness(backlight);
+	if (backlight->max_brightness < 0)
+		goto err;
+
+	backlight->brightness = backlight_get_actual_brightness(backlight);
+	if (backlight->brightness < 0)
+		goto err;
+
+	closedir(backlights);
+	return backlight;
+err:
+	closedir(backlights);
+	free (chosen_path);
+	free (backlight);
+	return NULL;
+}