[PATCH i-g-t 1/2] lib/igt_pm: Add helpers for hibernating kernel

[Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>]

Here added

igt_pm_check_hibernation_support()
igt_pm_ensure_grub_boots_same_kernel()

to check if kernel is configured for resuming from hibernation
and helper to set grub booting currently run kernel on next reboot.

Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
---
 lib/igt_pm.c | 155 +++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_pm.h |   2 +
 2 files changed, 157 insertions(+)

diff --git a/lib/igt_pm.c b/lib/igt_pm.c
index 1a5d9c42b..2055996bc 100644
--- a/lib/igt_pm.c
+++ b/lib/igt_pm.c
@@ -1470,3 +1470,158 @@ void igt_pm_ignore_slpc_efficient_freq(int i915, int gtfd, bool val)
 	igt_require(igt_sysfs_has_attr(gtfd, "slpc_ignore_eff_freq"));
 	igt_sysfs_set_u32(gtfd, "slpc_ignore_eff_freq", val);
 }
+
+/**
+ * igt_pm_check_hibernation_support:
+ *
+ * Return: True if kernel is configured with resume point for hibernate.
+ */
+bool igt_pm_check_hibernation_support(void)
+{
+	int fd;
+	char buffer[2048];
+	ssize_t bytes_read;
+	FILE *cmdline;
+
+	/* Check if hibernation is supported in /sys/power/state */
+	fd = open("/sys/power/state", O_RDONLY);
+
+	if (fd <= 0) {
+		igt_debug("Failed to open /sys/power/state\n");
+		return false;
+	}
+
+	bytes_read = read(fd, buffer, sizeof(buffer) - 1);
+	close(fd);
+
+	if (bytes_read <= 0) {
+		igt_debug("Failed to read /sys/power/state");
+		return false;
+	}
+
+	buffer[bytes_read] = '\0';
+	if (strstr(buffer, "disk") == NULL) {
+		igt_debug("Hibernation (suspend to disk) is not supported on this system.\n");
+		return false;
+	}
+
+	/* Check if resume is configured in kernel command line */
+	cmdline = fopen("/proc/cmdline", "r");
+
+	if (!cmdline) {
+		igt_debug("Failed to open /proc/cmdline");
+		return false;
+	}
+
+	fread(buffer, 1, sizeof(buffer) - 1, cmdline);
+	fclose(cmdline);
+
+	if (strstr(buffer, "resume=") == NULL) {
+		igt_debug("Kernel does not have 'resume' parameter configured for hibernation.\n");
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * igt_pm_ensure_grub_boots_same_kernel:
+ *
+ * Return: True if kernel was found and set for next reboot.
+ */
+bool igt_pm_ensure_grub_boots_same_kernel(void)
+{
+	char cmdline[1024];
+	char current_kernel[256];
+	char last_menuentry[512] = "";
+	char grub_entry[512];
+	char command[1024];
+	FILE *cmdline_file, *grub_cfg;
+	char line[1024];
+	bool kernel_found = false;
+	char *kernel_arg;
+	char *kernel_end;
+
+	/* Read /proc/cmdline to get the current kernel image */
+	cmdline_file = fopen("/proc/cmdline", "r");
+	if (!cmdline_file) {
+		igt_debug("Failed to open /proc/cmdline");
+		return false;
+	}
+
+	if (!fgets(cmdline, sizeof(cmdline), cmdline_file)) {
+		fclose(cmdline_file);
+		igt_debug("Failed to read /proc/cmdline");
+		return false;
+	}
+	fclose(cmdline_file);
+
+	/* Parse the kernel image from cmdline */
+	kernel_arg = strstr(cmdline, "BOOT_IMAGE=");
+	if (!kernel_arg) {
+		igt_debug("BOOT_IMAGE= not found in /proc/cmdline\n");
+		return false;
+	}
+
+	kernel_arg += strlen("BOOT_IMAGE=");
+	kernel_end = strchr(kernel_arg, ' ');
+
+	if (!kernel_end)
+		kernel_end = kernel_arg + strlen(kernel_arg);
+
+	snprintf(current_kernel, sizeof(current_kernel), "%.*s",
+		 (int)(kernel_end - kernel_arg), kernel_arg);
+	igt_debug("Current kernel image: %s\n", current_kernel);
+
+	/* Open GRUB config file to find matching entry */
+	grub_cfg = fopen("/boot/grub/grub.cfg", "r");
+	if (!grub_cfg) {
+		igt_debug("Failed to open GRUB configuration file");
+		return false;
+	}
+
+	while (fgets(line, sizeof(line), grub_cfg)) {
+		/* Check if the line contains a menuentry */
+		if (strstr(line, "menuentry")) {
+		/* Store the menuentry line */
+			char *start = strchr(line, '\'');
+			char *end = start ? strchr(start + 1, '\'') : NULL;
+
+			if (start && end) {
+				snprintf(last_menuentry,
+					 sizeof(last_menuentry),
+					 "%.*s", (int)(end - start - 1),
+					 start + 1);
+			}
+		}
+
+		/* Check if the current line contains the kernel */
+		if (strstr(line, current_kernel)) {
+			/* Use the last seen menuentry as the match */
+			snprintf(grub_entry, sizeof(grub_entry), "%s",
+				 last_menuentry);
+			kernel_found = true;
+			break;
+		}
+	}
+
+	fclose(grub_cfg);
+
+	if (!kernel_found) {
+		igt_debug("Failed to find matching GRUB entry for kernel: %s\n",
+			  current_kernel);
+		return false;
+	}
+
+	/* Set the GRUB boot target using grub-reboot */
+	snprintf(command, sizeof(command), "grub-reboot \"%s\"", grub_entry);
+	if (system(command) != 0) {
+		igt_debug("Failed to set GRUB boot target to: %s\n",
+			  grub_entry);
+		return false;
+	}
+
+	igt_debug("Set GRUB to boot kernel: %s (GRUB entry: %s)\n",
+		  current_kernel, grub_entry);
+	return true;
+}
diff --git a/lib/igt_pm.h b/lib/igt_pm.h
index 6b428f53e..7cc774e85 100644
--- a/lib/igt_pm.h
+++ b/lib/igt_pm.h
@@ -97,5 +97,7 @@ uint64_t igt_pm_get_runtime_suspended_time(struct pci_device *pci_dev);
 uint64_t igt_pm_get_runtime_active_time(struct pci_device *pci_dev);
 int igt_pm_get_runtime_usage(struct pci_device *pci_dev);
 void igt_pm_ignore_slpc_efficient_freq(int i915, int gtfd, bool val);
+bool igt_pm_check_hibernation_support(void);
+bool igt_pm_ensure_grub_boots_same_kernel(void);
 
 #endif /* IGT_PM_H */
-- 
2.45.2