compositor-drm: Just pull in libbacklight source for now

libbacklight is 300 lines of code in one .c file, and we're relying on
udev changes that aren't yet upstream.  For now, let's just keep a
copy in weston and if the Xorg DDX drivers start using libbacklight and
it becomes more widely available, we'll make it an external dependency.

configure.ac

@@ -73,7 +73,7 @@ AC_ARG_ENABLE(drm-compositor, [  --enable-drm-compositor],,
 AM_CONDITIONAL(ENABLE_DRM_COMPOSITOR, test x$enable_drm_compositor = xyes)
 if test x$enable_drm_compositor = xyes; then
   AC_DEFINE([BUILD_DRM_COMPOSITOR], [1], [Build the DRM compositor])
-  PKG_CHECK_MODULES(DRM_COMPOSITOR, [libbacklight libudev >= 136 libdrm >= 2.4.30 gbm])
+  PKG_CHECK_MODULES(DRM_COMPOSITOR, [libudev >= 136 libdrm >= 2.4.30 gbm])
 fi
 
 

src/Makefile.am

@@ -61,7 +61,13 @@ drm_backend = drm-backend.la
 drm_backend_la_LDFLAGS = -module -avoid-version
 drm_backend_la_LIBADD = $(COMPOSITOR_LIBS) $(DRM_COMPOSITOR_LIBS)
 drm_backend_la_CFLAGS = $(DRM_COMPOSITOR_CFLAGS) $(GCC_CFLAGS)
-drm_backend_la_SOURCES = compositor-drm.c tty.c evdev.c evdev.h
+drm_backend_la_SOURCES =			\
+	compositor-drm.c			\
+	tty.c					\
+	evdev.c					\
+	evdev.h					\
+	libbacklight.c				\
+	libbacklight.h
 endif
 
 if ENABLE_WAYLAND_COMPOSITOR

src/libbacklight.c

@@ -0,0 +1,322 @@
+/*
+ * 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>
+ */
+
+#define _GNU_SOURCE
+
+#include <libbacklight.h>
+#include <stdio.h>
+#include <linux/types.h>
+#include <dirent.h>
+#include <drm/drm_mode.h>
+#include <fcntl.h>
+#include <malloc.h>
+#include <string.h>
+#include <errno.h>
+
+static const char *output_names[] = { "Unknown",
+                                      "VGA",
+                                      "DVI-I",
+                                      "DVI-D",
+                                      "DVI-A",
+                                      "Composite",
+                                      "SVIDEO",
+                                      "LVDS",
+                                      "Component",
+                                      "9-pin DIN",
+				      "DisplayPort"
+                                      "HDMI Type A",
+                                      "HDMI Type B",
+                                      "TV",
+				      "Embedded DisplayPort"
+};
+
+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:
+	close(fd);
+	if (path)
+		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)
+		return -ENOMEM;
+
+	ret = write(fd, buffer, strlen(buffer));
+	if (ret < 0) {
+		ret = -1;
+		goto out;
+	}
+
+	ret = backlight_get_brightness(backlight);
+	backlight->brightness = ret;
+out:
+	if (buffer)
+		free(buffer);
+	if (path)
+		free(path);
+	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;
+	struct dirent *entry;
+	enum backlight_type type = 0;
+	char buffer[100];
+	struct backlight *backlight;
+	int err, 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));
+	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)
+			return NULL;
+
+		if (asprintf(&path, "%s/%s", backlight_path, "type") < 0)
+			return NULL;
+
+		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)
+			return NULL;
+
+		ret = readlink(path, buffer, sizeof(buffer));
+
+		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)
+		return NULL;
+
+	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;
+
+	return backlight;
+err:
+	if (chosen_path)
+		free(chosen_path);
+	free (backlight);
+	return NULL;
+}

src/libbacklight.h

@@ -0,0 +1,49 @@
+#ifndef LIBBACKLIGHT_H
+#define LIBBACKLIGHT_H
+#include <libudev.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif 
+
+enum backlight_type {
+	BACKLIGHT_RAW,
+	BACKLIGHT_PLATFORM,
+	BACKLIGHT_FIRMWARE,
+};
+
+struct backlight {
+	char *path;
+	int max_brightness;
+	int brightness;
+	enum backlight_type type;
+};
+
+/*
+ * Find and set up a backlight for a valid udev connector device, i.e. one
+ * matching drm subsytem and with status of connected.
+ */
+struct backlight *backlight_init(struct udev_device *drm_device,
+				 uint32_t connector_type);
+
+/* Free backlight resources */
+void backlight_destroy(struct backlight *backlight);
+
+/* Provide the maximum backlight value */
+long backlight_get_max_brightness(struct backlight *backlight);
+
+/* Provide the cached backlight value */
+long backlight_get_brightness(struct backlight *backlight);
+
+/* Provide the hardware backlight value */
+long backlight_get_actual_brightness(struct backlight *backlight);
+
+/* Set the backlight to a value between 0 and max */
+long backlight_set_brightness(struct backlight *backlight, long brightness);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* LIBBACKLIGHT_H */