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"); 222