drivers/thermal/pcie_cooling.c

   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
  20 static 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
  30 static 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
  40 static 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
  51 static 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
  57 struct 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
  67 void pcie_cooling_device_unregister(struct thermal_cooling_device *cdev)
  68 {
  69         thermal_cooling_device_unregister(cdev);
  70 }
  71
  72 /* For bus_speed <-> state arithmetic */
  73 static_assert(PCIE_SPEED_2_5GT + 1 == PCIE_SPEED_5_0GT);
  74 static_assert(PCIE_SPEED_5_0GT + 1 == PCIE_SPEED_8_0GT);
  75 static_assert(PCIE_SPEED_8_0GT + 1 == PCIE_SPEED_16_0GT);
  76 static_assert(PCIE_SPEED_16_0GT + 1 == PCIE_SPEED_32_0GT);
  77 static_assert(PCIE_SPEED_32_0GT + 1 == PCIE_SPEED_64_0GT);
  78
  79 MODULE_AUTHOR("Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>");
  80 MODULE_DESCRIPTION("PCIe cooling driver");