[LTP] [PATCH v3] testcases/kernel/device-drivers/nvme: Add NVMe device discovery test

[priyama2@linux.ibm.com]

From: priyama2 <priyama2@linux.ibm.com>

This test fills a gap in NVMe test coverage by validating basic device
enumeration and driver binding, which are fundamental prerequisites for
any NVMe functionality testing.

The test verifies:
- Detection of NVMe controllers in /dev
- Enumeration of namespaces for detected controllers
- PCI enumeration (class code 0x010802)
- NVMe driver binding

Changes in v3:
- Fix subject prefix to match directory path
- Update copyright year to 2026
- Add nvme to SUBDIRS in testcases/kernel/device-drivers/Makefile
- Reset static variables at start of run() for -i support
- Remove .needs_root (all operations are world-readable)
- Use SAFE_FOPEN/SAFE_FCLOSE for PCI class file access
- Use SAFE_READLINK for driver symlink reading
- Add .gitignore entry for nvme01 binary
- Add runtest/device-drivers entry for nvme01
- Fix author field to use priyama2

Changes in v2:
- Use LTP buildsystem instead of standalone Makefile
- Remove README file (use doc comments instead)
- Add proper LTP documentation comment format
- Use SAFE_OPENDIR() and SAFE_CLOSEDIR() macros
- Remove obvious and redundant comments
- Code cleanup and style improvements

Signed-off-by: priyama2 <priyama2@linux.ibm.com>
---
 runtest/device-drivers                        |   1 +
 testcases/kernel/device-drivers/Makefile      |   1 +
 .../kernel/device-drivers/nvme/.gitignore     |   1 +
 testcases/kernel/device-drivers/nvme/Makefile |   7 +
 testcases/kernel/device-drivers/nvme/nvme01.c | 205 ++++++++++++++++++
 5 files changed, 215 insertions(+)
 create mode 100644 runtest/device-drivers
 create mode 100644 testcases/kernel/device-drivers/nvme/.gitignore
 create mode 100644 testcases/kernel/device-drivers/nvme/Makefile
 create mode 100644 testcases/kernel/device-drivers/nvme/nvme01.c

diff --git a/runtest/device-drivers b/runtest/device-drivers
new file mode 100644
index 000000000..a7295584e
--- /dev/null
+++ b/runtest/device-drivers
@@ -0,0 +1 @@
+nvme01 nvme01
diff --git a/testcases/kernel/device-drivers/Makefile b/testcases/kernel/device-drivers/Makefile
index 229a50683..664f4cd18 100644
--- a/testcases/kernel/device-drivers/Makefile
+++ b/testcases/kernel/device-drivers/Makefile
@@ -9,6 +9,7 @@ SUBDIRS		:= acpi \
 		   block \
 		   cpufreq \
 		   locking \
+		   nvme \
 		   pci \
 		   rcu \
 		   rtc \
diff --git a/testcases/kernel/device-drivers/nvme/.gitignore b/testcases/kernel/device-drivers/nvme/.gitignore
new file mode 100644
index 000000000..c60bc210c
--- /dev/null
+++ b/testcases/kernel/device-drivers/nvme/.gitignore
@@ -0,0 +1 @@
+nvme01
diff --git a/testcases/kernel/device-drivers/nvme/Makefile b/testcases/kernel/device-drivers/nvme/Makefile
new file mode 100644
index 000000000..d47e99e6a
--- /dev/null
+++ b/testcases/kernel/device-drivers/nvme/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2024 IBM Corporation
+
+top_srcdir	?= ../../../..
+
+include $(top_srcdir)/include/mk/env_pre.mk
+include $(top_srcdir)/include/mk/generic_trunk_target.mk
diff --git a/testcases/kernel/device-drivers/nvme/nvme01.c b/testcases/kernel/device-drivers/nvme/nvme01.c
new file mode 100644
index 000000000..3c3cb92ce
--- /dev/null
+++ b/testcases/kernel/device-drivers/nvme/nvme01.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 IBM Corporation
+ * Author: priyama2 <priyama2@linux.ibm.com>
+ */
+
+/* * [Description]
+ *
+ * Verify NVMe device discovery and identification.
+ *
+ * This test fills a gap in NVMe test coverage by validating basic device
+ * enumeration and driver binding, which are fundamental prerequisites for
+ * any NVMe functionality testing.
+ *
+ * - Detect NVMe controllers in /dev
+ * - Enumerate namespaces for detected controllers
+ * - Verify PCI enumeration (class code 0x010802)
+ * - Check NVMe driver binding
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <errno.h>
+
+#include "tst_test.h"
+#include "tst_safe_stdio.h"
+
+#define NVME_DEV_PATH "/dev"
+#define NVME_SYS_PATH "/sys/class/nvme"
+#define PCI_DEVICES_PATH "/sys/bus/pci/devices"
+
+static int nvme_device_found;
+static char nvme_dev_name[256];
+
+static void test_detect_nvme_controllers(void)
+{
+	DIR *dir;
+	struct dirent *entry;
+	int found = 0;
+
+	dir = SAFE_OPENDIR(NVME_DEV_PATH);
+
+	tst_res(TINFO, "Scanning for NVMe devices in %s", NVME_DEV_PATH);
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (strncmp(entry->d_name, "nvme", 4) == 0 &&
+		    strlen(entry->d_name) == 5) {
+			tst_res(TINFO, "Found NVMe controller: %s", entry->d_name);
+			strncpy(nvme_dev_name, entry->d_name, sizeof(nvme_dev_name) - 1);
+			found = 1;
+			nvme_device_found = 1;
+		}
+	}
+
+	SAFE_CLOSEDIR(dir);
+
+	if (found)
+		tst_res(TPASS, "NVMe controller(s) detected successfully");
+	else
+		tst_res(TCONF, "No NVMe controllers found in system");
+}
+
+static void test_enumerate_namespaces(void)
+{
+	DIR *dir;
+	struct dirent *entry;
+	int ns_count = 0;
+	char search_pattern[32];
+
+	if (!nvme_device_found) {
+		tst_res(TCONF, "No NVMe device found, skipping namespace enumeration");
+		return;
+	}
+
+	snprintf(search_pattern, sizeof(search_pattern), "%sn", nvme_dev_name);
+
+	dir = SAFE_OPENDIR(NVME_DEV_PATH);
+
+	tst_res(TINFO, "Enumerating namespaces for %s", nvme_dev_name);
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (strncmp(entry->d_name, search_pattern, strlen(search_pattern)) == 0) {
+			tst_res(TINFO, "Found namespace: %s", entry->d_name);
+			ns_count++;
+		}
+	}
+
+	SAFE_CLOSEDIR(dir);
+
+	if (ns_count > 0)
+		tst_res(TPASS, "Enumerated %d namespace(s) successfully", ns_count);
+	else
+		tst_res(TPASS, "No namespaces found for %s (device may not have namespaces configured)", nvme_dev_name);
+}
+
+static void test_verify_pci_enumeration(void)
+{
+	DIR *dir;
+	struct dirent *entry;
+	int found = 0;
+	char class_path[512];
+	FILE *fp;
+	char class_id[16];
+
+	if (!nvme_device_found) {
+		tst_res(TCONF, "No NVMe device found, skipping PCI enumeration check");
+		return;
+	}
+
+	dir = SAFE_OPENDIR(PCI_DEVICES_PATH);
+
+	tst_res(TINFO, "Checking PCI enumeration for NVMe devices");
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (entry->d_name[0] == '.')
+			continue;
+
+		snprintf(class_path, sizeof(class_path), "%s/%s/class",
+			 PCI_DEVICES_PATH, entry->d_name);
+
+		fp = SAFE_FOPEN(class_path, "r");
+
+		if (fgets(class_id, sizeof(class_id), fp)) {
+			if (strncmp(class_id, "0x010802", 8) == 0) {
+				tst_res(TINFO, "Found NVMe PCI device: %s (class: %s)",
+					entry->d_name, class_id);
+				found = 1;
+			}
+		}
+		SAFE_FCLOSE(fp);
+	}
+
+	SAFE_CLOSEDIR(dir);
+
+	if (found)
+		tst_res(TPASS, "NVMe device properly enumerated on PCI bus");
+	else
+		tst_res(TFAIL, "NVMe device not found on PCI bus");
+}
+
+static void test_check_driver_binding(void)
+{
+	char driver_path[512];
+	char driver_link[512];
+
+	if (!nvme_device_found) {
+		tst_res(TCONF, "No NVMe device found, skipping driver binding check");
+		return;
+	}
+
+	snprintf(driver_path, sizeof(driver_path), "%s/%s/device/driver",
+		 NVME_SYS_PATH, nvme_dev_name);
+
+	SAFE_READLINK(driver_path, driver_link, sizeof(driver_link));
+
+	tst_res(TINFO, "Driver binding: %s", driver_link);
+
+	if (strstr(driver_link, "nvme") != NULL)
+		tst_res(TPASS, "NVMe driver properly bound to device");
+	else
+		tst_res(TFAIL, "Unexpected driver bound to NVMe device: %s", driver_link);
+}
+
+static void setup(void)
+{
+	if (access("/sys/module/nvme", F_OK) != 0)
+		tst_brk(TCONF, "NVMe kernel module not loaded");
+
+	tst_res(TINFO, "NVMe Device Discovery & Identification Test");
+}
+
+static void run(unsigned int n)
+{
+	/* Reset state for each iteration */
+	nvme_device_found = 0;
+	memset(nvme_dev_name, 0, sizeof(nvme_dev_name));
+
+	switch (n) {
+	case 0:
+		test_detect_nvme_controllers();
+		break;
+	case 1:
+		test_enumerate_namespaces();
+		break;
+	case 2:
+		test_verify_pci_enumeration();
+		break;
+	case 3:
+		test_check_driver_binding();
+		break;
+	}
+}
+
+static struct tst_test test = {
+	.test = run,
+	.tcnt = 4,
+	.setup = setup,
+};
-- 
2.52.0


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