[igt-dev] [PATCH i-g-t 2/4] Introduce device selection API

[Arkadiusz Hiler <arkadiusz.hiler@intel.com>]

From: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>

Change adds device selection API based on scanning drm subsystem
using udev library.

v2 (Arek):
 * drop most of the glib code in favor of igt_list and plain C
 * make sysfs paths handling non-special - introduce sys: filter
 * drop multiple filter_* structs in favor of just two:
   - filter_class for defining filters types (e.g. sys:)
   - filter for "filter instance" - the data provided by the user
 * promote many macros to real functions for type safety
 * rename devs->devs to devs->all
 * rename devs->view to devs->filtered
 * don't expose "chip" (e.g. DRIVER_ANY) as it's unreadable as int
 * update docs to reflect those changes
 * move open functions that open igt_device_card to this patch
 * remove platform filter class for now
 * use only a single filter

Cc: Petri Latvala <petri.latvala@intel.com>
Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
---
 .../igt-gpu-tools/igt-gpu-tools-docs.xml      |    1 +
 lib/Makefile.sources                          |    2 +
 lib/igt_device_scan.c                         | 1199 +++++++++++++++++
 lib/igt_device_scan.h                         |   67 +
 lib/meson.build                               |    1 +
 5 files changed, 1270 insertions(+)
 create mode 100644 lib/igt_device_scan.c
 create mode 100644 lib/igt_device_scan.h

diff --git a/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml b/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
index 3f14d7be..c41cbb78 100644
--- a/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
+++ b/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
@@ -23,6 +23,7 @@
     <xi:include href="xml/igt_core.xml"/>
     <xi:include href="xml/igt_debugfs.xml"/>
     <xi:include href="xml/igt_device.xml"/>
+    <xi:include href="xml/igt_device_scan.xml"/>
     <xi:include href="xml/igt_draw.xml"/>
     <xi:include href="xml/igt_dummyload.xml"/>
     <xi:include href="xml/igt_fb.xml"/>
diff --git a/lib/Makefile.sources b/lib/Makefile.sources
index 1b58b6d0..7e8594c5 100644
--- a/lib/Makefile.sources
+++ b/lib/Makefile.sources
@@ -25,6 +25,8 @@ lib_source_list =	 	\
 	igt_debugfs.h		\
 	igt_device.c		\
 	igt_device.h		\
+	igt_device_scan.c	\
+	igt_device_scan.h	\
 	igt_aux.c		\
 	igt_aux.h		\
 	igt_color_encoding.c	\
diff --git a/lib/igt_device_scan.c b/lib/igt_device_scan.c
new file mode 100644
index 00000000..71d30587
--- /dev/null
+++ b/lib/igt_device_scan.c
@@ -0,0 +1,1199 @@
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * 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.
+ *
+ */
+
+#include "igt.h"
+#include "igt_list.h"
+#include "igt_sysfs.h"
+#include "igt_device.h"
+#include "igt_device_scan.h"
+#include <glib.h>
+#include <libudev.h>
+#include <linux/limits.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <fcntl.h>
+
+/**
+ * SECTION:igt_device_scan
+ * @short_description: Device scanning and selection
+ * @title: Device selection
+ * @include: igt.h
+ *
+ * # Device scanning
+ *
+ * Device scanning iterates over DRM subsystem using udev library
+ * to acquire DRM devices.
+ * For each DRM device we also get and store its parent to allow device
+ * selection happen in a more contextual way.
+ *
+ * Parent devices are bus devices (like PCI, platform, etc.) and contain a lot
+ * of extra data on top of the DRM device itself.
+ *
+ * # Filters
+ *
+ * Device selection can be done using filters that are using the data collected
+ * udev + some syntactic sugar.
+ *
+ * Direct device selection filter uses sysfs path to find the device:
+ *
+ * |[<!-- language="plain" -->
+ * sys:/sys/path/to/device/or/parent
+ * ]|
+ *
+ * Examples:
+ * |[<!-- language="plain" -->
+ * - sys:/sys/devices/pci0000:00/0000:00:02.0/drm/card0
+ * - sys:/sys/devices/pci0000:00/0000:00:02.0
+ * - sys:/sys/devices/platform/vgem
+ * ]|
+ *
+ * The alternative is to use other implemented filters:
+ *
+ * - drm: get drm /dev/dri/... device directly
+ *
+ *   |[<!-- language="plain" -->
+ *   drm:/dev/dri/...
+ *   ]|
+ *
+ *   Loading drivers in different order can cause different ordering of
+ *   /dev/dri/card nodes which be problematic for reliable and reproducible
+ *   device selection, e.g. in automated execution setting. In such scenarios
+ *   please consider using sys, pci or platform filters instead.
+ *
+ * - pci: select device using PCI vendor and device properties
+ *   |[<!-- language="plain" -->
+ *   pci:[vendor=%04x/name][,device=%04x][,card=%d]
+ *   ]|
+ *
+ *   Filter allows device selection using vendor (hex or name), device id
+ *   (hex) and nth-card from all matches. For example if there are 4 PCI cards
+ *   installed (let two cards have 1234 and other two 1235 device id, all of
+ *   them of vendor Intel) you can select one using:
+ *
+ *   |[<!-- language="plain" -->
+ *   pci:vendor=Intel,device=1234,card=0
+ *   ]|
+ *
+ *   or
+ *
+ *   |[<!-- language="plain" -->
+ *   pci:vendor=8086,device=1234,card=0
+ *   ]|
+ *
+ *   This takes first device with 1234 id for Intel vendor (8086).
+ *
+ *   |[<!-- language="plain" -->
+ *   pci:vendor=Intel,device=1234,card=1
+ *   ]|
+ *
+ *   or
+ *
+ *   |[<!-- language="plain" -->
+ *   pci:vendor=8086,device=1234,card=1
+ *   ]|
+ *
+ *   It selects the second one.
+ *
+ *   As order the on PCI bus doesn't change (unless you'll add new device or
+ *   reorder existing one) device selection using this filter will always
+ *   return you same device regardless the order of enumeration.
+ *
+ *   Simple syntactic sugar over using the sysfs paths.
+ */
+
+#ifdef DEBUG_DEVICE_SCAN
+#define DBG(...) \
+{ \
+	struct timeval tm; \
+	gettimeofday(&tm, NULL); \
+	printf("%10ld.%03ld: ", tm.tv_sec, tm.tv_usec); \
+	printf(__VA_ARGS__); \
+	}
+
+#else
+#define DBG(...) {}
+#endif
+
+static inline bool strequal(const char *a, const char *b)
+{
+	if (a == NULL || b == NULL)
+		return false;
+
+	return strcmp(a, b) == 0;
+}
+
+struct igt_device {
+	/* Filled for drm devices */
+	struct igt_device *parent;
+
+	/* Point to vendor spec if can be found */
+
+	/* Properties / sysattrs rewriten from udev lists */
+	GHashTable *props_ht;
+	GHashTable *attrs_ht;
+
+	/* Most usable variables from udev device */
+	char *subsystem;
+	char *syspath;
+	char *devnode;
+
+	/* /dev/dri/... paths */
+	char *drm_card;
+	char *drm_render;
+
+	/* For pci subsystem */
+	char *vendor;
+	char *device;
+
+	struct igt_list link;
+};
+
+/* Scanned devices */
+static struct {
+	struct igt_list all;
+	struct igt_list filtered;
+	bool devs_scanned;
+} igt_devs;
+
+static struct {
+	const char *name;
+	const char *vendor_id;
+} pci_vendor_mapping[] = {
+	{ "intel", "8086" },
+	{ "amd", "1002" },
+	{ NULL, },
+};
+
+static const char *get_pci_vendor_id_by_name(const char *name)
+{
+	for (typeof(*pci_vendor_mapping) *vm = pci_vendor_mapping; vm->name; vm++)
+	{
+		if (!strcasecmp(name, vm->name))
+			return vm->vendor_id;
+	}
+
+	return NULL;
+}
+
+/* Reading sysattr values can take time (even seconds),
+ * we want to avoid reading such keys.
+ */
+static bool is_on_blacklist(const char *what)
+{
+	static const char *keys[] = { "config", "modalias", "modes",
+				      "resource",
+				      "resource0", "resource1", "resource2",
+				      "resource3", "resource4", "resource5",
+				      "resource0_wc", "resource1_wc", "resource2_wc",
+				      "resource3_wc", "resource4_wc", "resource5_wc",
+				      "driver",
+				      "uevent", NULL};
+	const char *key;
+	int i = 0;
+
+	if (what == NULL)
+		return false;
+
+	while ((key = keys[i++])) {
+		if (strcmp(key, what) == 0)
+			return true;
+	}
+
+	return false;
+
+}
+
+static struct igt_device *igt_device_new(void)
+{
+	struct igt_device *dev;
+
+	dev = calloc(1, sizeof(struct igt_device));
+	if (!dev)
+		return NULL;
+
+	dev->attrs_ht = g_hash_table_new_full(g_str_hash, g_str_equal,
+					      free, free);
+	dev->props_ht = g_hash_table_new_full(g_str_hash, g_str_equal,
+					      free, free);
+
+	if (dev->attrs_ht && dev->props_ht)
+		return dev;
+
+	return NULL;
+}
+
+static void igt_device_add_prop(struct igt_device *dev,
+				const char *key, const char *value)
+{
+	if (!key || !value)
+		return;
+
+	g_hash_table_insert(dev->props_ht, strdup(key), strdup(value));
+}
+
+static void igt_device_add_attr(struct igt_device *dev,
+				const char *key, const char *value)
+{
+	const char *v = value;
+
+	if (!key)
+		return;
+
+	/* It's possible we have symlink at key filename, but udev
+	 * library resolves only few of them
+	 */
+	if (!v) {
+		struct stat st;
+		char path[PATH_MAX];
+		char linkto[PATH_MAX];
+		int len;
+
+		snprintf(path, sizeof(path), "%s/%s", dev->syspath, key);
+		if (lstat(path, &st) != 0)
+			return;
+
+		len = readlink(path, linkto, sizeof(linkto));
+		if (len <= 0 || len == (ssize_t) sizeof(linkto))
+			return;
+		linkto[len] = '\0';
+		v = strrchr(linkto, '/');
+		if (v == NULL)
+			return;
+		v++;
+	}
+
+	g_hash_table_insert(dev->attrs_ht, strdup(key), strdup(v));
+}
+
+/* Iterate over udev properties list and rewrite it to igt_device properties
+ * hash table for instant access.
+ */
+static void get_props(struct udev_device *dev, struct igt_device *idev)
+{
+	struct udev_list_entry *entry;
+
+	entry = udev_device_get_properties_list_entry(dev);
+	while (entry) {
+		const char *name = udev_list_entry_get_name(entry);
+		const char *value = udev_list_entry_get_value(entry);
+
+		igt_device_add_prop(idev, name, value);
+		entry = udev_list_entry_get_next(entry);
+		DBG("prop: %s, val: %s\n", name, value);
+	}
+}
+
+/* Same as get_props(), but rewrites sysattrs. Resolves symbolic links
+ * not handled by udev get_sysattr_value().
+ * Function skips sysattrs from blacklist ht (acquiring some values can take
+ * seconds).
+ */
+static void get_attrs(struct udev_device *dev, struct igt_device *idev)
+{
+	struct udev_list_entry *entry;
+
+	entry = udev_device_get_sysattr_list_entry(dev);
+	while (entry) {
+		const char *key = udev_list_entry_get_name(entry);
+		const char *value;
+
+		if (is_on_blacklist(key)) {
+			entry = udev_list_entry_get_next(entry);
+			continue;
+		}
+
+		value = udev_device_get_sysattr_value(dev, key);
+		igt_device_add_attr(idev, key, value);
+		entry = udev_list_entry_get_next(entry);
+		DBG("attr: %s, val: %s\n", key, value);
+	}
+}
+
+#define get_prop(dev, prop) ((char *) g_hash_table_lookup(dev->props_ht, prop))
+#define get_attr(dev, attr) ((char *) g_hash_table_lookup(dev->attrs_ht, attr))
+#define get_prop_subsystem(dev) get_prop(dev, "SUBSYSTEM")
+#define is_drm_subsystem(dev)  (strequal(get_prop_subsystem(dev), "drm"))
+#define is_pci_subsystem(dev)  (strequal(get_prop_subsystem(dev), "pci"))
+
+/* Gets PCI_ID property, splits to xxxx:yyyy and stores
+ * xxxx to dev->vendor and yyyy to dev->device for
+ * faster access.
+ */
+static void set_vendor_device(struct igt_device *dev)
+{
+	const char *pci_id = get_prop(dev, "PCI_ID");
+
+	if (!pci_id || strlen(pci_id) != 9)
+		return;
+	dev->vendor = strndup(pci_id, 4);
+	dev->device = strndup(pci_id + 5, 4);
+}
+
+/* Allocate arrays for keeping scanned devices */
+static bool prepare_scan(void)
+{
+	if (igt_devs.all.prev == NULL || igt_devs.all.next == NULL)
+		igt_list_init(&igt_devs.all);
+
+	if (igt_devs.filtered.prev == NULL || igt_devs.filtered.next == NULL)
+		igt_list_init(&igt_devs.filtered);
+
+
+	return true;
+}
+
+static char* strdup_nullsafe(const char* str)
+{
+	if (str == NULL)
+		return NULL;
+
+	return strdup(str);
+}
+
+/* Create new igt_device from udev device.
+ * Fills structure with most usable udev device variables, properties
+ * and sysattrs.
+ */
+static struct igt_device *igt_device_new_from_udev(struct udev_device *dev)
+{
+	struct igt_device *idev = igt_device_new();
+
+	igt_assert(idev);
+	idev->syspath = strdup_nullsafe(udev_device_get_syspath(dev));
+	idev->subsystem = strdup_nullsafe(udev_device_get_subsystem(dev));
+	idev->devnode = strdup_nullsafe(udev_device_get_devnode(dev));
+
+	if (idev->devnode && strstr(idev->devnode, "/dev/dri/card"))
+		idev->drm_card = strdup(idev->devnode);
+	else if (idev->devnode && strstr(idev->devnode, "/dev/dri/render"))
+		idev->drm_render = strdup(idev->devnode);
+
+	get_props(dev, idev);
+	get_attrs(dev, idev);
+
+	return idev;
+}
+
+/* Iterate over all igt_devices array and find one matched to
+ * subsystem and syspath.
+ */
+static struct igt_device *igt_device_find(const char *subsystem,
+					  const char *syspath)
+{
+	struct igt_device *dev;
+
+	igt_list_for_each(dev, &igt_devs.all, link)
+	{
+		if (strcmp(dev->subsystem, subsystem) == 0 &&
+			strcmp(dev->syspath, syspath) == 0)
+			return dev;
+	}
+
+	return NULL;
+}
+
+static struct igt_device *igt_device_from_syspath(const char *syspath)
+{
+	struct igt_device *dev;
+
+	igt_list_for_each(dev, &igt_devs.all, link)
+	{
+		if (strcmp(dev->syspath, syspath) == 0)
+			return dev;
+	}
+
+	return NULL;
+}
+
+/* For each drm igt_device add or update its parent igt_device to the array.
+ * As card/render drm devices mostly have same parent (vkms is an exception)
+ * link to it and update corresponding drm_card / drm_render fields.
+ */
+static void update_or_add_parent(struct udev_device *dev,
+				 struct igt_device *idev)
+{
+	struct udev_device *parent_dev;
+	struct igt_device *parent_idev;
+	const char *subsystem, *syspath, *devname;
+
+	parent_dev = udev_device_get_parent(dev);
+	igt_assert(parent_dev);
+
+	subsystem = udev_device_get_subsystem(parent_dev);
+	syspath = udev_device_get_syspath(parent_dev);
+
+	parent_idev = igt_device_find(subsystem, syspath);
+	if (!parent_idev) {
+		parent_idev = igt_device_new_from_udev(parent_dev);
+		if (is_pci_subsystem(parent_idev)) {
+			set_vendor_device(parent_idev);
+		}
+		igt_list_insert_tail(&igt_devs.all, &parent_idev->link);
+	}
+	devname = udev_device_get_devnode(dev);
+	if (devname != NULL && strstr(devname, "/dev/dri/card"))
+		parent_idev->drm_card = strdup(devname);
+	else if (devname != NULL && strstr(devname, "/dev/dri/render"))
+		parent_idev->drm_render = strdup(devname);
+
+	idev->parent = parent_idev;
+}
+
+static struct igt_device *duplicate_device(struct igt_device *dev) {
+	struct igt_device *dup = malloc(sizeof(*dup));
+	memcpy(dup, dev, sizeof(*dev));
+	dup->link.prev = NULL;
+	dup->link.next = NULL;
+	return dup;
+}
+
+static gint devs_compare(const void *a, const void *b)
+{
+	struct igt_device *dev1, *dev2;
+	int ret;
+
+	dev1 = *(struct igt_device **) a;
+	dev2 = *(struct igt_device **) b;
+	ret = strcmp(dev1->subsystem, dev2->subsystem);
+	if (ret)
+		return ret;
+
+	return strcmp(dev1->syspath, dev2->syspath);
+}
+
+static void sort_all_devices(void)
+{
+	struct igt_device *dev, *tmp;
+	int len = igt_list_length(&igt_devs.all);
+	struct igt_device **devs = malloc(len * sizeof(*dev));
+
+	int i = 0;
+	igt_list_for_each_safe(dev, tmp, &igt_devs.all, link) {
+		devs[i] = dev;
+		igt_assert(i++ < len);
+		igt_list_remove(&dev->link);
+	}
+
+	qsort(devs, len, sizeof(*devs), devs_compare);
+
+	for (i = 0; i < len; ++i) {
+		igt_list_insert_tail(&igt_devs.all, &devs[i]->link);
+	}
+}
+
+/* Core scanning function.
+ *
+ * All scanned devices are kept inside igt_devs.all pointer array.
+ * Each added device is igt_device structure, which contrary to udev device
+ * has properties / sysattrs stored inside hash table instead of list.
+ *
+ * Function iterates over devices on 'drm' subsystem. For each drm device
+ * its parent is taken (bus device) and stored inside same array.
+ * Function sorts all found devices to keep same order of bus devices
+ * for providing predictable search.
+ */
+static void scan_drm_devices(void)
+{
+	struct udev *udev;
+	struct udev_enumerate *enumerate;
+	struct udev_list_entry *devices, *dev_list_entry;
+	struct igt_device *dev;
+	int ret;
+
+	udev = udev_new();
+	igt_assert(udev);
+
+	enumerate = udev_enumerate_new(udev);
+	igt_assert(enumerate);
+
+	DBG("Scanning drm subsystem\n");
+	ret = udev_enumerate_add_match_subsystem(enumerate, "drm");
+	igt_assert(!ret);
+
+	udev_enumerate_add_match_property(enumerate, "DEVNAME", "/dev/dri/*");
+	igt_assert(!ret);
+
+	ret = udev_enumerate_scan_devices(enumerate);
+	igt_assert(!ret);
+
+	devices = udev_enumerate_get_list_entry(enumerate);
+	if (!devices)
+		return;
+
+	udev_list_entry_foreach(dev_list_entry, devices) {
+		const char *path;
+		struct udev_device *udev_dev;
+		struct igt_device *idev;
+
+		path = udev_list_entry_get_name(dev_list_entry);
+		udev_dev = udev_device_new_from_syspath(udev, path);
+		idev = igt_device_new_from_udev(udev_dev);
+		update_or_add_parent(udev_dev, idev);
+		igt_list_insert_tail(&igt_devs.all, &idev->link);
+
+		udev_device_unref(udev_dev);
+	}
+	udev_enumerate_unref(enumerate);
+	udev_unref(udev);
+
+	sort_all_devices();
+
+	igt_list_for_each(dev, &igt_devs.all, link) {
+		struct igt_device *dev_dup = duplicate_device(dev);
+		igt_list_insert_tail(&igt_devs.filtered, &dev_dup->link);
+	}
+}
+
+static void igt_device_free(struct igt_device *dev)
+{
+	free(dev->devnode);
+	free(dev->subsystem);
+	free(dev->syspath);
+	free(dev->drm_card);
+	free(dev->drm_render);
+	free(dev->vendor);
+	free(dev->device);
+	g_hash_table_destroy(dev->attrs_ht);
+	g_hash_table_destroy(dev->props_ht);
+}
+
+/**
+ * igt_devices_scan
+ * @force: enforce scanning devices
+ *
+ * Function scans udev in search of gpu devices. For first run it can be
+ * called with @force = false. If something changes during the the test
+ * or test does some module loading (new drm devices occurs during execution)
+ * function must be called again with @force = true to refresh device array.
+ */
+void igt_devices_scan(bool force)
+{
+	if (force && igt_devs.devs_scanned) {
+		struct igt_device *dev, *tmp;
+		igt_list_for_each_safe(dev, tmp, &igt_devs.all, link) {
+			igt_device_free(dev);
+			free(dev);
+		}
+
+		igt_devs.devs_scanned = false;
+	}
+
+	if (igt_devs.devs_scanned)
+		return;
+
+	prepare_scan();
+	scan_drm_devices();
+
+	igt_devs.devs_scanned = true;
+}
+
+static inline void _pr_simple(const char *k, const char *v)
+{
+	printf("    %-16s: %s\n", k, v);
+}
+
+static inline void _pr_simple2(const char *k, const char *v1, const char *v2)
+{
+	printf("    %-16s: %s:%s\n", k, v1, v2);
+}
+
+static void igt_devs_print_simple(struct igt_list *view)
+{
+	struct igt_device *dev;
+
+	if (!view)
+		return;
+
+	if (igt_list_empty(view)) {
+		printf("No GPU devices found\n");
+		return;
+	}
+
+	igt_list_for_each(dev, view, link) {
+		printf("sys:%s\n", dev->syspath);
+		if (dev->subsystem)
+			_pr_simple("subsystem", dev->subsystem);
+		if (dev->drm_card)
+			_pr_simple("drm card", dev->drm_card);
+		if (dev->drm_render)
+			_pr_simple("drm render", dev->drm_render);
+		if (is_drm_subsystem(dev)) {
+			_pr_simple2("parent", "sys",
+				   dev->parent->syspath);
+		} else {
+			if (is_pci_subsystem(dev)) {
+				_pr_simple("vendor", dev->vendor);
+				_pr_simple("device", dev->device);
+			}
+		}
+		printf("\n");
+	}
+}
+
+static inline void _print_key_value(const char* k, const char *v)
+{
+	printf("%-32s: %s\n", k, v);
+}
+
+static void print_ht(GHashTable *ht)
+{
+	GList *keys = g_hash_table_get_keys(ht);
+
+	keys = g_list_sort(keys, (GCompareFunc) strcmp);
+	while (keys) {
+		char *k = (char *) keys->data;
+		char *v = g_hash_table_lookup(ht, k);
+
+		_print_key_value(k, v);
+		keys = g_list_next(keys);
+	}
+	g_list_free(keys);
+}
+
+static void igt_devs_print_detail(struct igt_list *view)
+{
+	struct igt_device *dev;
+
+	if (!view)
+		return;
+
+	if (igt_list_empty(view)) {
+		printf("No GPU devices found\n");
+		return;
+	}
+
+	igt_list_for_each(dev, view, link) {
+		printf("========== %s:%s ==========\n",
+		       dev->subsystem, dev->syspath);
+		if (!is_drm_subsystem(dev)) {
+			_print_key_value("card device", dev->drm_card);
+			_print_key_value("render device", dev->drm_render);
+		}
+
+		printf("\n[properties]\n");
+		print_ht(dev->props_ht);
+		printf("\n[attributes]\n");
+		print_ht(dev->attrs_ht);
+		printf("\n");
+	}
+}
+
+static struct print_func {
+	void (*prn)(struct igt_list *view);
+} print_functions[] = {
+	[IGT_PRINT_SIMPLE] = { .prn = igt_devs_print_simple },
+	[IGT_PRINT_DETAIL] = { .prn = igt_devs_print_detail },
+};
+
+/**
+ * igt_devices_print
+ * @printtype: IGT_PRINT_SIMPLE or IGT_PRINT_DETAIL
+ *
+ * Function can be used by external tool to print device array in simple
+ * or detailed form. This function is added here to avoid exposing
+ * internal implementation data structures.
+ */
+void igt_devices_print(enum igt_devices_print_type printtype)
+{
+	print_functions[printtype].prn(&igt_devs.filtered);
+}
+
+/**
+ * igt_devices_print_vendors
+ *
+ * Print pci id -> vendor mappings. Vendor names printed by this function
+ * can be used for filters like pci which allows passing vendor - like
+ * vendor id (8086) or as a string (Intel).
+ */
+void igt_devices_print_vendors(void)
+{
+	printf("Recognized vendors:\n");
+	printf("%-8s %-16s\n", "PCI ID", "vendor");
+	for (typeof(*pci_vendor_mapping) *vm = pci_vendor_mapping; vm->name; vm++) {
+		printf("%-8s %-16s\n", vm->vendor_id, vm->name);
+	}
+}
+
+struct filter;
+
+/* ------------------------------------------------------------------------- */
+struct filter_class {
+	struct igt_list *(*filter_function)(const struct filter_class *fcls,
+					    const struct filter *filter);
+	bool (*is_valid)(const struct filter_class *fcls,
+			 const struct filter *filter);
+	const char *name;
+	const char *help;
+	const char *detail;
+};
+
+#define FILTER_NAME_LEN 32
+#define FILTER_DATA_LEN 256
+
+struct filter {
+	struct filter_class *class;
+
+	char raw_data[FILTER_DATA_LEN];
+
+	struct {
+		char *vendor;
+		char *device;
+		char *card;
+		char *drm;
+		char *driver;
+	} data;
+};
+
+static void fill_filter_data(struct filter *filter, const char *key, const char *value)
+{
+	if (key == NULL || value == NULL) {
+		return;
+	}
+
+#define __fill_key(name) if (strcmp(key, #name) == 0) \
+	filter->data.name = strdup(value)
+	__fill_key(vendor);
+	__fill_key(device);
+	__fill_key(card);
+	__fill_key(drm);
+	__fill_key(driver);
+#undef __fill_key
+
+}
+
+static void split_filter_data(struct filter *filter)
+{
+	char *property, *key, *data, *dup;
+
+	dup = strdup(filter->raw_data);
+	data = dup;
+
+	while ((property = strsep(&data, ","))) {
+		key = strsep(&property, "=");
+		fill_filter_data(filter, key, property);
+	}
+
+	free(dup);
+}
+
+static struct filter_class *get_filter_class(const char *class_name, const struct filter *filter);
+
+static bool parse_filter(const char *fstr, struct filter *filter)
+{
+	char class_name[32];
+	if (!fstr || !filter)
+		return false;
+
+	memset(filter, 0, sizeof(*filter));
+
+
+	if (sscanf(fstr, "%31[^:]:%255s", class_name, filter->raw_data) >= 1) {
+		filter->class = get_filter_class(class_name, filter);
+		split_filter_data(filter);
+		return true;
+	}
+
+	return false;
+}
+
+static bool is_vendor_matched(struct igt_device *dev, const char *vendor)
+{
+	const char *vendor_id;
+
+	if (!dev->vendor || !vendor)
+		return false;
+
+	/* First we compare vendor id, like 8086 */
+	if (!strcasecmp(dev->vendor, vendor))
+		return true;
+
+	/* Likely we have vendor string instead of id */
+	vendor_id = get_pci_vendor_id_by_name(vendor);
+	if (!vendor_id)
+		return false;
+
+	return !strcasecmp(dev->vendor, vendor_id);
+}
+
+/* Filter which matches subsystem:/sys/... path.
+ * Used as first filter in chain.
+ */
+static struct igt_list *filter_sys(const struct filter_class *fcls,
+				   const struct filter *filter)
+{
+	struct igt_device *dev;
+	(void) fcls;
+
+	DBG("filter sys\n");
+	if (!strlen(filter->raw_data))
+		return &igt_devs.filtered;
+
+	dev = igt_device_from_syspath(filter->raw_data);
+	if (dev) {
+		struct igt_device *dup = duplicate_device(dev);
+		igt_list_insert_tail(&igt_devs.filtered, &dup->link);
+	}
+
+	return &igt_devs.filtered;
+}
+
+/* Find drm device using direct path to /dev/dri/.
+ * It extends filter_sys to allow using drm:/dev/dri/cardX and
+ * drm:/dev/dri/renderDX filter syntax.
+ */
+static struct igt_list *filter_drm(const struct filter_class *fcls,
+				   const struct filter *filter)
+{
+	struct igt_device *dev;
+	(void) fcls;
+
+	DBG("filter drm\n");
+	if (!strlen(filter->raw_data))
+		return &igt_devs.filtered;
+
+	igt_list_for_each(dev, &igt_devs.all, link) {
+		if (!is_drm_subsystem(dev))
+			continue;
+
+		if (strequal(dev->syspath, filter->raw_data) ||
+			strequal(dev->drm_card, filter->raw_data) ||
+			strequal(dev->drm_render, filter->raw_data)) {
+			struct igt_device *dup = duplicate_device(dev);
+			igt_list_insert_tail(&igt_devs.filtered, &dup->link);
+			break;
+		}
+	}
+
+
+	return &igt_devs.filtered;
+}
+
+/* Find appropriate pci device matching vendor/device/card filter arguments.
+ */
+static struct igt_list *filter_pci(const struct filter_class *fcls,
+				   const struct filter *filter)
+{
+	struct igt_device *dev;
+	int card = -1;
+	(void) fcls;
+
+	DBG("filter pci\n");
+
+	if (filter->data.card) {
+		sscanf(filter->data.card, "%d", &card);
+		if (card < 0) {
+			return &igt_devs.filtered;
+		}
+	} else {
+		card = 0;
+	}
+
+	igt_list_for_each(dev, &igt_devs.all, link) {
+		if (!is_pci_subsystem(dev))
+			continue;
+
+		/* Skip if 'vendor' doesn't match (hex or name) */
+		if (filter->data.vendor && !is_vendor_matched(dev, filter->data.vendor))
+			continue;
+
+		/* Skip if 'device' doesn't match */
+		if (filter->data.device && strcasecmp(filter->data.device, dev->device))
+			continue;
+
+		/* We get n-th card */
+		if (!card) {
+			struct igt_device *dup = duplicate_device(dev);
+			igt_list_insert_tail(&igt_devs.filtered, &dup->link);
+			break;
+		}
+		card--;
+	}
+
+	DBG("Filter pci filtered size: %d\n", igt_list_length(&igt_devs.filtered));
+
+	return &igt_devs.filtered;
+}
+
+static bool sys_path_valid(const struct filter_class *fcls,
+			   const struct filter *filter)
+{
+	struct stat st;
+
+	if (stat(filter->raw_data, &st)) {
+		igt_warn("sys_path_valid: syspath [%s], err: %s\n",
+			 filter->raw_data, strerror(errno));
+		return false;
+	}
+
+	return true;
+}
+
+
+static struct filter_class filter_definition_list[] = {
+	{
+		.name = "sys",
+		.is_valid = sys_path_valid,
+		.filter_function = filter_sys,
+		.help = "sys:/sys/devices/pci0000:00/0000:00:02.0",
+		.detail = "find device byt its sysfs path\n",
+	},
+	{
+		.name = "drm",
+		.filter_function = filter_drm,
+		.help = "drm:/dev/dri/* path",
+		.detail = "find drm device by /dev/dri/* node\n",
+	},
+	{
+		.name = "pci",
+		.filter_function = filter_pci,
+		.help = "pci:[vendor=%04x/name][,device=%04x][,card=%d]",
+		.detail = "vendor is hex number or vendor name\n",
+	},
+	{
+		.name = NULL,
+	},
+};
+
+static struct filter_class *get_filter_class(const char *class_name, const struct filter *filter)
+{
+	struct filter_class *fcls = NULL;
+	int i = 0;
+
+	while ((fcls = &filter_definition_list[i++])->name != NULL) {
+		if (strcmp(class_name, fcls->name) == 0)
+			return fcls;
+	}
+
+	return NULL;
+}
+
+/**
+ * @igt_device_print_filter_types
+ *
+ * Print all filters syntax for device selection.
+ */
+void igt_device_print_filter_types(void)
+{
+	const struct filter_class *filter = NULL;
+	int i = 0;
+
+	printf("Filter types:\n---\n");
+	printf("%-12s  %s\n---\n", "filter", "syntax");
+
+	while ((filter = &filter_definition_list[i++])->name != NULL) {
+		printf("%-12s  %s\n", filter->name, filter->help);
+		printf("%-12s  %s\n", "", filter->detail);
+	}
+}
+
+static char *device_filter;
+
+/**
+ * igt_device_is_filter_set
+ *
+ * Returns whether we have a filter set.
+ */
+bool igt_device_is_filter_set(void)
+{
+	return device_filter != NULL;
+}
+
+/* Check does filter is valid. It checks:
+ * 1. /sys/... path first
+ * 2. filter name from filter definition
+ */
+static bool is_filter_valid(const char *fstr)
+{
+	struct filter filter;
+	int ret;
+
+	ret = parse_filter(fstr, &filter);
+	if (!ret)
+		return false;
+
+	if (filter.class == NULL) {
+		igt_warn("No filter matching [%s:%s]\n", filter.class->name, filter.raw_data);
+		return false;
+	}
+
+	if (filter.class->is_valid != NULL && !filter.class->is_valid(filter.class, &filter))
+	{
+		igt_warn("Filter not valid [%s:%s]\n", filter.class->name, filter.raw_data);
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * igt_device_filter_set
+ * @filter: filter that should be set globally
+ *
+ * Returns number of filters added to filter array. Can be greater than
+ * 1 if @filters contains more than one filter separated by semicolon.
+ */
+void igt_device_filter_set(const char *filter)
+{
+	if (!is_filter_valid(filter)) {
+		igt_warn("Invalid filter: %s\n", filter);
+		return;
+	}
+
+	device_filter = strdup(filter);
+}
+
+/**
+ * igt_device_filter_free
+ *
+ * Free the filter that we store internally, effectively insetting it.
+ */
+void igt_device_filter_free(void)
+{
+	if (device_filter != NULL)
+		free(device_filter);
+}
+
+/**
+ * igt_device_filter_get
+ *
+ * Returns filter string or NULL if not set
+ */
+const char *igt_device_filter_get(void)
+{
+	return device_filter;
+}
+
+static bool igt_device_filter_apply(const char *fstr)
+{
+	struct igt_device *dev, *tmp;
+	struct filter filter;
+	bool ret;
+
+	if (!fstr)
+		return false;
+
+	ret = parse_filter(fstr, &filter);
+	if (!ret) {
+		igt_warn("Can't split filter [%s]\n", fstr);
+		return false;
+	}
+
+	/* Clean the filtered list */
+	igt_list_for_each_safe(dev, tmp, &igt_devs.filtered, link) {
+		igt_list_remove(&dev->link);
+		free(dev);
+	}
+
+	/* If filter.data contains "/sys" use direct path instead
+	 * contextual filter.
+	 */
+
+	if (!filter.class) {
+		igt_warn("No filter matching [%s:%s]\n", filter.class->name, filter.raw_data);
+		return false;
+	}
+	filter.class->filter_function(filter.class, &filter);
+
+	return true;
+}
+
+/**
+ * igt_device_card_match
+ * @filter: filter string
+ * @card: pointer to igt_device_card struct
+ *
+ * Function applies filter to match device from device array.
+ *
+ * Returns:
+ * false - no card pointer was passed or card wasn't matched,
+ * true - card matched and returned.
+ */
+bool igt_device_card_match(const char *filter, struct igt_device_card *card)
+{
+	struct igt_device *dev = NULL;
+
+	if (!card)
+		return false;
+	memset(card, 0, sizeof(*card));
+
+	igt_devices_scan(false);
+
+	if (igt_device_filter_apply(filter) == false)
+		return false;
+
+	if (igt_list_empty(&igt_devs.filtered))
+		return false;
+
+	/* We take first one if more than one card matches filter */
+	dev = igt_list_first_entry(&igt_devs.filtered, dev, link);
+
+	if (dev->subsystem != NULL)
+		strncpy(card->subsystem, dev->subsystem,
+			     sizeof(card->subsystem) - 1);
+
+	if (dev->drm_card != NULL)
+		strncpy(card->card, dev->drm_card,
+			     sizeof(card->card) - 1);
+
+	if (dev->drm_render != NULL)
+		strncpy(card->render, dev->drm_render,
+			     sizeof(card->render) - 1);
+
+	return true;
+}
+
+/**
+ * igt_open_card:
+ * @card: pointer to igt_device_card structure
+ *
+ * Open /dev/dri/cardX device represented by igt_device_card structure.
+ * Requires filled @card argument (see igt_device_card_match() function).
+ *
+ * An open DRM fd or -1 on error
+ */
+int igt_open_card(struct igt_device_card *card)
+{
+	if (!card || !strlen(card->card))
+		return -1;
+
+	return open(card->card, O_RDWR);
+}
+
+/**
+ * igt_open_render:
+ * @card: pointer to igt_device_card structure
+ *
+ * Open /dev/dri/renderDX device represented by igt_device_card structure.
+ * Requires filled @card argument (see igt_device_card_match() function).
+ *
+ * An open DRM fd or -1 on error
+ */
+int igt_open_render(struct igt_device_card *card)
+{
+	if (!card || !strlen(card->render))
+		return -1;
+
+	return open(card->render, O_RDWR);
+}
diff --git a/lib/igt_device_scan.h b/lib/igt_device_scan.h
new file mode 100644
index 00000000..dbde8816
--- /dev/null
+++ b/lib/igt_device_scan.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * 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.
+ *
+ */
+
+#ifndef __IGT_DEVICE_SCAN_H__
+#define __IGT_DEVICE_SCAN_H__
+
+#include <limits.h>
+#include <igt.h>
+
+enum igt_devices_print_type {
+	IGT_PRINT_SIMPLE,
+	IGT_PRINT_DETAIL,
+};
+
+struct igt_device_card {
+	char subsystem[NAME_MAX];
+	char card[NAME_MAX];
+	char render[NAME_MAX];
+};
+
+/* Scan udev subsystems. Do it once unless force is true, what rescans
+ * devices again.
+ */
+void igt_devices_scan(bool force);
+
+void igt_devices_print(enum igt_devices_print_type printtype);
+void igt_devices_print_vendors(void);
+void igt_device_print_filter_types(void);
+
+/*
+ * Handle device filter collection array.
+ * IGT can store/retrieve filters passed by user using '--device' args.
+ */
+
+bool igt_device_is_filter_set(void);
+void igt_device_filter_set(const char *filter);
+void igt_device_filter_free(void);
+const char *igt_device_filter_get(void);
+
+/* Use filter to match the device and fill card structure */
+bool igt_device_card_match(const char *filter, struct igt_device_card *card);
+
+int igt_open_card(struct igt_device_card *card);
+int igt_open_render(struct igt_device_card *card);
+
+#endif /* __IGT_DEVICE_SCAN_H__ */
diff --git a/lib/meson.build b/lib/meson.build
index 19cb6255..486f51d7 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -10,6 +10,7 @@ lib_sources = [
 	'igt_color_encoding.c',
 	'igt_debugfs.c',
 	'igt_device.c',
+	'igt_device_scan.c',
 	'igt_aux.c',
 	'igt_gt.c',
 	'igt_gvt.c',
-- 
2.21.0

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