drivers/thermal/testing/command.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2024, Intel Corporation
   4  *
   5  * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
   6  *
   7  * Thermal subsystem testing facility.
   8  *
   9  * This facility allows the thermal core functionality to be exercised in a
  10  * controlled way in order to verify its behavior.
  11  *
  12  * It resides in the "thermal-testing" directory under the debugfs root and
  13  * starts with a single file called "command" which can be written a string
  14  * representing a thermal testing facility command.
  15  *
  16  * The currently supported commands are listed in the tt_commands enum below.
  17  *
  18  * The "addtz" command causes a new test thermal zone template to be created,
  19  * for example:
  20  *
  21  * # echo addtz > /sys/kernel/debug/thermal-testing/command
  22  *
  23  * That template will be represented as a subdirectory in the "thermal-testing"
  24  * directory, for example
  25  *
  26  * # ls /sys/kernel/debug/thermal-testing/
  27  * command tz0
  28  *
  29  * The thermal zone template can be populated with trip points with the help of
  30  * the "tzaddtrip" command, for example:
  31  *
  32  * # echo tzaddtrip:0 > /sys/kernel/debug/thermal-testing/command
  33  *
  34  * which causes a trip point template to be added to the test thermal zone
  35  * template 0 (represented by the tz0 subdirectory in "thermal-testing").
  36  *
  37  * # ls /sys/kernel/debug/thermal-testing/tz0
  38  * init_temp temp trip_0_temp trip_0_hyst
  39  *
  40  * The temperature of a trip point template is initially THERMAL_TEMP_INVALID
  41  * and its hysteresis is initially 0.  They can be adjusted by writing to the
  42  * "trip_x_temp" and "trip_x_hyst" files correspoinding to that trip point
  43  * template, respectively.
  44  *
  45  * The initial temperature of a thermal zone based on a template can be set by
  46  * writing to the "init_temp" file in its directory under "thermal-testing", for
  47  * example:
  48  *
  49  * echo 50000 > /sys/kernel/debug/thermal-testing/tz0/init_temp
  50  *
  51  * When ready, "tzreg" command can be used for registering and enabling a
  52  * thermal zone based on a given template with the thermal core, for example
  53  *
  54  * # echo tzreg:0 > /sys/kernel/debug/thermal-testing/command
  55  *
  56  * In this case, test thermal zone template 0 is used for registering a new
  57  * thermal zone and the set of trip point templates associated with it is used
  58  * for populating the new thermal zone's trip points table.  The type of the new
  59  * thermal zone is "test_tz".
  60  *
  61  * The temperature and hysteresis of all of the trip points in that new thermal
  62  * zone are adjustable via sysfs, so they can be updated at any time.
  63  *
  64  * The current temperature of the new thermal zone can be set by writing to the
  65  * "temp" file in the corresponding thermal zone template's directory under
  66  * "thermal-testing", for example
  67  *
  68  * echo 10000 > /sys/kernel/debug/thermal-testing/tz0/temp
  69  *
  70  * which will also trigger a temperature update for this zone in the thermal
  71  * core, including checking its trip points, sending notifications to user space
  72  * if any of them have been crossed and so on.
  73  *
  74  * When it is not needed any more, a test thermal zone template can be deleted
  75  * with the help of the "deltz" command, for example
  76  *
  77  * # echo deltz:0 > /sys/kernel/debug/thermal-testing/command
  78  *
  79  * which will also unregister the thermal zone based on it, if present.
  80  */
  81
  82 #define pr_fmt(fmt) "thermal-testing: " fmt
  83
  84 #include <linux/debugfs.h>
  85 #include <linux/module.h>
  86
  87 #include "thermal_testing.h"
  88
  89 struct dentry *d_testing;
  90
  91 #define TT_COMMAND_SIZE         16
  92
  93 enum tt_commands {
  94         TT_CMD_ADDTZ,
  95         TT_CMD_DELTZ,
  96         TT_CMD_TZADDTRIP,
  97         TT_CMD_TZREG,
  98         TT_CMD_TZUNREG,
  99 };
 100
 101 static const char *tt_command_strings[] = {
 102         [TT_CMD_ADDTZ] = "addtz",
 103         [TT_CMD_DELTZ] = "deltz",
 104         [TT_CMD_TZADDTRIP] = "tzaddtrip",
 105         [TT_CMD_TZREG] = "tzreg",
 106         [TT_CMD_TZUNREG] = "tzunreg",
 107 };
 108
 109 static int tt_command_exec(int index, const char *arg)
 110 {
 111         int ret;
 112
 113         switch (index) {
 114         case TT_CMD_ADDTZ:
 115                 ret = tt_add_tz();
 116                 break;
 117
 118         case TT_CMD_DELTZ:
 119                 ret = tt_del_tz(arg);
 120                 break;
 121
 122         case TT_CMD_TZADDTRIP:
 123                 ret = tt_zone_add_trip(arg);
 124                 break;
 125
 126         case TT_CMD_TZREG:
 127                 ret = tt_zone_reg(arg);
 128                 break;
 129
 130         case TT_CMD_TZUNREG:
 131                 ret = tt_zone_unreg(arg);
 132                 break;
 133
 134         default:
 135                 ret = -EINVAL;
 136                 break;
 137         }
 138
 139         return ret;
 140 }
 141
 142 static ssize_t tt_command_process(struct dentry *dentry, const char __user *user_buf,
 143                                   size_t count)
 144 {
 145         char *buf __free(kfree);
 146         char *arg;
 147         int i;
 148
 149         buf = kmalloc(count + 1, GFP_KERNEL);
 150         if (!buf)
 151                 return -ENOMEM;
 152
 153         if (copy_from_user(buf, user_buf, count))
 154                 return -EFAULT;
 155
 156         buf[count] = '\0';
 157         strim(buf);
 158
 159         arg = strstr(buf, ":");
 160         if (arg) {
 161                 *arg = '\0';
 162                 arg++;
 163         }
 164
 165         for (i = 0; i < ARRAY_SIZE(tt_command_strings); i++) {
 166                 if (!strcmp(buf, tt_command_strings[i]))
 167                         return tt_command_exec(i, arg);
 168         }
 169
 170         return -EINVAL;
 171 }
 172
 173 static ssize_t tt_command_write(struct file *file, const char __user *user_buf,
 174                                 size_t count, loff_t *ppos)
 175 {
 176         struct dentry *dentry = file->f_path.dentry;
 177         ssize_t ret;
 178
 179         if (*ppos)
 180                 return -EINVAL;
 181
 182         if (count + 1 > TT_COMMAND_SIZE)
 183                 return -E2BIG;
 184
 185         ret = debugfs_file_get(dentry);
 186         if (unlikely(ret))
 187                 return ret;
 188
 189         ret = tt_command_process(dentry, user_buf, count);
 190         if (ret)
 191                 return ret;
 192
 193         return count;
 194 }
 195
 196 static const struct file_operations tt_command_fops = {
 197         .write = tt_command_write,
 198         .open =  simple_open,
 199         .llseek = default_llseek,
 200 };
 201
 202 static int __init thermal_testing_init(void)
 203 {
 204         d_testing = debugfs_create_dir("thermal-testing", NULL);
 205         if (!IS_ERR(d_testing))
 206                 debugfs_create_file("command", 0200, d_testing, NULL,
 207                                     &tt_command_fops);
 208
 209         return 0;
 210 }
 211 module_init(thermal_testing_init);
 212
 213 static void __exit thermal_testing_exit(void)
 214 {
 215         debugfs_remove(d_testing);
 216         tt_zone_cleanup();
 217 }
 218 module_exit(thermal_testing_exit);
 219
 220 MODULE_DESCRIPTION("Thermal core testing facility");
 221 MODULE_LICENSE("GPL v2");