1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * PCIe cooling device
 4 *
 5 * Copyright (C) 2023-2024 Intel Corporation
 6 */
 7
 8#include <linux/build_bug.h>
 9#include <linux/cleanup.h>
10#include <linux/err.h>
11#include <linux/module.h>
12#include <linux/pci.h>
13#include <linux/pci-bwctrl.h>
14#include <linux/slab.h>
15#include <linux/sprintf.h>
16#include <linux/thermal.h>
17
18#define COOLING_DEV_TYPE_PREFIX		"PCIe_Port_Link_Speed_"
19
20static int pcie_cooling_get_max_level(struct thermal_cooling_device *cdev, unsigned long *state)
21{
22	struct pci_dev *port = cdev->devdata;
23
24	/* cooling state 0 is same as the maximum PCIe speed */
25	*state = port->subordinate->max_bus_speed - PCIE_SPEED_2_5GT;
26
27	return 0;
28}
29
30static int pcie_cooling_get_cur_level(struct thermal_cooling_device *cdev, unsigned long *state)
31{
32	struct pci_dev *port = cdev->devdata;
33
34	/* cooling state 0 is same as the maximum PCIe speed */
35	*state = cdev->max_state - (port->subordinate->cur_bus_speed - PCIE_SPEED_2_5GT);
36
37	return 0;
38}
39
40static int pcie_cooling_set_cur_level(struct thermal_cooling_device *cdev, unsigned long state)
41{
42	struct pci_dev *port = cdev->devdata;
43	enum pci_bus_speed speed;
44
45	/* cooling state 0 is same as the maximum PCIe speed */
46	speed = (cdev->max_state - state) + PCIE_SPEED_2_5GT;
47
48	return pcie_set_target_speed(port, speed, true);
49}
50
51static struct thermal_cooling_device_ops pcie_cooling_ops = {
52	.get_max_state = pcie_cooling_get_max_level,
53	.get_cur_state = pcie_cooling_get_cur_level,
54	.set_cur_state = pcie_cooling_set_cur_level,
55};
56
57struct thermal_cooling_device *pcie_cooling_device_register(struct pci_dev *port)
58{
59	char *name __free(kfree) =
60		kasprintf(GFP_KERNEL, COOLING_DEV_TYPE_PREFIX "%s", pci_name(port));
61	if (!name)
62		return ERR_PTR(-ENOMEM);
63
64	return thermal_cooling_device_register(name, port, &pcie_cooling_ops);
65}
66
67void pcie_cooling_device_unregister(struct thermal_cooling_device *cdev)
68{
69	thermal_cooling_device_unregister(cdev);
70}
71
72/* For bus_speed <-> state arithmetic */
73static_assert(PCIE_SPEED_2_5GT + 1 == PCIE_SPEED_5_0GT);
74static_assert(PCIE_SPEED_5_0GT + 1 == PCIE_SPEED_8_0GT);
75static_assert(PCIE_SPEED_8_0GT + 1 == PCIE_SPEED_16_0GT);
76static_assert(PCIE_SPEED_16_0GT + 1 == PCIE_SPEED_32_0GT);
77static_assert(PCIE_SPEED_32_0GT + 1 == PCIE_SPEED_64_0GT);
78
79MODULE_AUTHOR("Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>");
80MODULE_DESCRIPTION("PCIe cooling driver");