/* SPDX-License-Identifier: BSD-3-Clause */
/* Copyright (c) 2026 Open-IOV contributors */
/* rm_api.c - RM ioctl client, GPU discovery and control plumbing.
 *
 * The ioctl ladder (root -> device -> subdevice) and NV_ESC_RM_CONTROL
 * pattern follow tools/rmq/rmq.c and tools/guest-diag/guest_engines.c.
 * All operations here are control-path only; no kernel module, VFIO or
 * device state is modified.
 */
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>

#include "rm_api.h"

#define CONTROL_NODE "/dev/nvidiactl"

static NvU32 rm_alloc_root(int fd, NvHandle *out)
{
	NVOS21_PARAMETERS p = { 0 };

	p.hRoot = 0;
	p.hObjectParent = 0;
	p.hClass = NV01_ROOT_CLIENT;
	if (ioctl(fd, NV_IOCTL_RM_ALLOC21, &p) < 0)
		return (NvU32)-1;
	if (p.status != 0)
		return p.status;
	*out = p.hObjectNew;
	return 0;
}

static NvU32 rm_alloc64(int fd, NvHandle hRoot, NvHandle hParent,
			NvU32 hClass, void *params, NvU32 params_size,
			NvHandle *out)
{
	NVOS64_PARAMETERS p = { 0 };

	p.hRoot = hRoot;
	p.hObjectParent = hParent;
	p.hClass = hClass;
	p.pAllocParms = (NvP64)params;
	p.paramsSize = params_size;
	p.flags = NVOS64_FLAGS_NONE;
	if (ioctl(fd, NV_IOCTL_RM_ALLOC64, &p) < 0)
		return (NvU32)-1;
	if (p.status != 0)
		return p.status;
	*out = p.hObjectNew;
	return 0;
}

static NvU32 rm_version_check(int fd)
{
	nv_ioctl_rm_api_version_t v = { 0 };

	v.cmd = NV_RM_API_VERSION_CMD_QUERY;
	if (ioctl(fd, NV_IOCTL_CHECK_VERSION, &v) < 0)
		return (NvU32)-1;
	if (v.reply != NV_RM_API_VERSION_REPLY_RECOGNIZED)
		return (NvU32)-2;
	return 0;
}

/* The open module registers a GPU once its device node open completes; a
 * NV01_DEVICE_0 alloc issued before that fails with NV_ERR_INVALID_STATE.
 */
static int rm_wait_gpu_open(int gpu_minor, const char *dev_path, int *gpu_fd)
{
	nv_ioctl_wait_open_complete_t w = { 0 };
	char path[64];
	int fd;

	if (dev_path != NULL) {
		snprintf(path, sizeof(path), "%s", dev_path);
	} else if (gpu_minor >= 0) {
		snprintf(path, sizeof(path), "/dev/nvidia%d", gpu_minor);
	} else {
		snprintf(path, sizeof(path), "/dev/nvidia0");
	}
	fd = open(path, O_RDWR | O_NONBLOCK | O_CLOEXEC);
	if (fd < 0)
		return -errno;
	if (ioctl(fd, NV_IOCTL_WAIT_OPEN_COMPLETE, &w) < 0) {
		int err = -errno;

		close(fd);
		return err;
	}
	if (w.rc != 0) {
		close(fd);
		return w.rc;
	}
	*gpu_fd = fd;
	return 0;
}

int rm_client_open(struct rm_client *c, int gpu_minor, const char *dev_path)
{
	NV0080_ALLOC_PARAMETERS dev_params;
	NV2080_ALLOC_PARAMETERS sub_params;
	NvU32 status;
	int rc;

	memset(c, 0, sizeof(*c));
	c->fd = -1;
	c->gpu_fd = -1;
	c->gpu_minor = gpu_minor >= 0 ? gpu_minor : 0;
	c->fd = open(CONTROL_NODE, O_RDWR | O_CLOEXEC);
	if (c->fd < 0)
		return -errno;

	status = rm_version_check(c->fd);
	if (status != 0) {
		fprintf(stderr, "rmtool: RM version check failed: %s\n",
			rm_status_str(status));
		rm_client_close(c);
		return (int)status;
	}

	rc = rm_wait_gpu_open(gpu_minor, dev_path, &c->gpu_fd);
	if (rc != 0) {
		fprintf(stderr, "rmtool: GPU open/complete failed: %s\n",
			strerror(-rc));
		rm_client_close(c);
		return rc;
	}

	status = rm_alloc_root(c->fd, &c->hClient);
	if (status != 0) {
		fprintf(stderr, "rmtool: NV01_ROOT_CLIENT alloc failed: "
			"0x%x\n", status);
		rm_client_close(c);
		return (int)status;
	}

	memset(&dev_params, 0, sizeof(dev_params));
	dev_params.deviceId = (NvU32)c->gpu_minor;
	status = rm_alloc64(c->fd, c->hClient, c->hClient, NV01_DEVICE_0,
			    &dev_params, sizeof(dev_params), &c->hDevice);
	if (status != 0) {
		fprintf(stderr, "rmtool: NV01_DEVICE_0 alloc failed: 0x%x\n",
			status);
		rm_client_close(c);
		return (int)status;
	}

	memset(&sub_params, 0, sizeof(sub_params));
	sub_params.subDeviceId = 0;
	status = rm_alloc64(c->fd, c->hClient, c->hDevice, NV20_SUBDEVICE_0,
			    &sub_params, sizeof(sub_params), &c->hSubdevice);
	if (status != 0) {
		fprintf(stderr, "rmtool: NV20_SUBDEVICE_0 alloc failed: "
			"0x%x\n", status);
		rm_client_close(c);
		return (int)status;
	}
	return 0;
}

void rm_client_close(struct rm_client *c)
{
	if (c->gpu_fd >= 0)
		close(c->gpu_fd);
	if (c->fd >= 0)
		close(c->fd);
	c->fd = -1;
	c->gpu_fd = -1;
	c->hClient = 0;
	c->hDevice = 0;
	c->hSubdevice = 0;
}

NvU32 rm_control(struct rm_client *c, NvU32 hObject, NvU32 cmd,
		 void *params, NvU32 size, int *ioctl_ret)
{
	NVOS54_PARAMETERS p = { 0 };

	p.hClient = c->hClient;
	p.hObject = hObject;
	p.cmd = cmd;
	p.params = (NvP64)params;
	p.paramsSize = size;
	if (ioctl(c->fd, NV_IOCTL_RM_CONTROL, &p) < 0) {
		if (ioctl_ret)
			*ioctl_ret = -errno;
		return (NvU32)-1;
	}
	if (ioctl_ret)
		*ioctl_ret = 0;
	return p.status;
}

const char *rm_status_str(NvU32 status)
{
	static char buf[32];

	if (status == 0)
		return "NV_OK";
	snprintf(buf, sizeof(buf), "NV_STATUS(0x%x)", status);
	return buf;
}

/* ------------------------------------------------------------------ */
/* /proc/driver/nvidia/gpus discovery                                  */
/* ------------------------------------------------------------------ */

static void copy_trim(char *dst, size_t len, const char *src)
{
	size_t n;

	while (*src == ' ' || *src == '\t')
		src++;
	n = strcspn(src, "\r\n");
	if (n >= len)
		n = len - 1;
	memcpy(dst, src, n);
	dst[n] = '\0';
	while (n > 0 && (dst[n - 1] == ' ' || dst[n - 1] == '\t'))
		dst[--n] = '\0';
}

static void parse_information(const char *path, struct rm_gpu_desc *gpu)
{
	FILE *fh;
	char line[512];

	fh = fopen(path, "r");
	if (fh == NULL)
		return;
	while (fgets(line, sizeof(line), fh) != NULL) {
		char *colon = strchr(line, ':');

		if (colon == NULL)
			continue;
		*colon = '\0';
		if (strcmp(line, "Model") == 0)
			copy_trim(gpu->model, sizeof(gpu->model), colon + 1);
		else if (strcmp(line, "GPU UUID") == 0)
			copy_trim(gpu->uuid, sizeof(gpu->uuid), colon + 1);
		else if (strcmp(line, "Video BIOS") == 0)
			copy_trim(gpu->vbios, sizeof(gpu->vbios), colon + 1);
		else if (strcmp(line, "Bus Location") == 0)
			copy_trim(gpu->bdf, sizeof(gpu->bdf), colon + 1);
		else if (strcmp(line, "IRQ") == 0)
			gpu->irq = atoi(colon + 1);
		else if (strcmp(line, "Device Minor") == 0)
			gpu->minor = atoi(colon + 1);
	}
	fclose(fh);
}

static int gpu_compare(const void *a, const void *b)
{
	const struct rm_gpu_desc *ga = a;
	const struct rm_gpu_desc *gb = b;

	return ga->minor - gb->minor;
}

int rm_scan_gpus(struct rm_gpu_desc *out, int max)
{
	const char *root = "/proc/driver/nvidia/gpus";
	DIR *dir;
	struct dirent *ent;
	int n = 0;

	dir = opendir(root);
	if (dir == NULL)
		return -errno;
	while ((ent = readdir(dir)) != NULL && n < max) {
		char info[512];
		struct rm_gpu_desc *gpu = &out[n];

		if (ent->d_name[0] == '.')
			continue;
		memset(gpu, 0, sizeof(*gpu));
		gpu->minor = -1;
		copy_trim(gpu->bdf, sizeof(gpu->bdf), ent->d_name);
		snprintf(info, sizeof(info), "%s/%s/information", root,
			 ent->d_name);
		parse_information(info, gpu);
		n++;
	}
	closedir(dir);
	qsort(out, n, sizeof(*out), gpu_compare);
	return n;
}