2 * A hwmon driver for ACPI 4.0 power meters
3 * Copyright (C) 2009 IBM
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 #include <linux/module.h>
23 #include <linux/hwmon.h>
24 #include <linux/hwmon-sysfs.h>
25 #include <linux/jiffies.h>
26 #include <linux/mutex.h>
27 #include <linux/dmi.h>
28 #include <linux/slab.h>
29 #include <linux/kdev_t.h>
30 #include <linux/sched.h>
31 #include <linux/time.h>
32 #include <linux/err.h>
33 #include <acpi/acpi_drivers.h>
34 #include <acpi/acpi_bus.h>
36 #define ACPI_POWER_METER_NAME "power_meter"
37 ACPI_MODULE_NAME(ACPI_POWER_METER_NAME);
38 #define ACPI_POWER_METER_DEVICE_NAME "Power Meter"
39 #define ACPI_POWER_METER_CLASS "pwr_meter_resource"
41 #define NUM_SENSORS 17
43 #define POWER_METER_CAN_MEASURE (1 << 0)
44 #define POWER_METER_CAN_TRIP (1 << 1)
45 #define POWER_METER_CAN_CAP (1 << 2)
46 #define POWER_METER_CAN_NOTIFY (1 << 3)
47 #define POWER_METER_IS_BATTERY (1 << 8)
48 #define UNKNOWN_HYSTERESIS 0xFFFFFFFF
50 #define METER_NOTIFY_CONFIG 0x80
51 #define METER_NOTIFY_TRIP 0x81
52 #define METER_NOTIFY_CAP 0x82
53 #define METER_NOTIFY_CAPPING 0x83
54 #define METER_NOTIFY_INTERVAL 0x84
56 #define POWER_AVERAGE_NAME "power1_average"
57 #define POWER_CAP_NAME "power1_cap"
58 #define POWER_AVG_INTERVAL_NAME "power1_average_interval"
59 #define POWER_ALARM_NAME "power1_alarm"
61 static int cap_in_hardware;
62 static bool force_cap_on;
64 static int can_cap_in_hardware(void)
66 return force_cap_on || cap_in_hardware;
69 static const struct acpi_device_id power_meter_ids[] = {
73 MODULE_DEVICE_TABLE(acpi, power_meter_ids);
75 struct acpi_power_meter_capabilities {
89 struct acpi_power_meter_resource {
90 struct acpi_device *acpi_dev;
93 struct device *hwmon_dev;
94 struct acpi_power_meter_capabilities caps;
95 acpi_string model_number;
96 acpi_string serial_number;
102 unsigned long sensors_last_updated;
103 struct sensor_device_attribute sensors[NUM_SENSORS];
106 int num_domain_devices;
107 struct acpi_device **domain_devices;
108 struct kobject *holders_dir;
111 struct sensor_template {
113 ssize_t (*show)(struct device *dev,
114 struct device_attribute *devattr,
116 ssize_t (*set)(struct device *dev,
117 struct device_attribute *devattr,
118 const char *buf, size_t count);
122 /* Averaging interval */
123 static int update_avg_interval(struct acpi_power_meter_resource *resource)
125 unsigned long long data;
128 status = acpi_evaluate_integer(resource->acpi_dev->handle, "_GAI",
130 if (ACPI_FAILURE(status)) {
131 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _GAI"));
135 resource->avg_interval = data;
139 static ssize_t show_avg_interval(struct device *dev,
140 struct device_attribute *devattr,
143 struct acpi_device *acpi_dev = to_acpi_device(dev);
144 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
146 mutex_lock(&resource->lock);
147 update_avg_interval(resource);
148 mutex_unlock(&resource->lock);
150 return sprintf(buf, "%llu\n", resource->avg_interval);
153 static ssize_t set_avg_interval(struct device *dev,
154 struct device_attribute *devattr,
155 const char *buf, size_t count)
157 struct acpi_device *acpi_dev = to_acpi_device(dev);
158 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
159 union acpi_object arg0 = { ACPI_TYPE_INTEGER };
160 struct acpi_object_list args = { 1, &arg0 };
163 unsigned long long data;
166 res = kstrtoul(buf, 10, &temp);
170 if (temp > resource->caps.max_avg_interval ||
171 temp < resource->caps.min_avg_interval)
173 arg0.integer.value = temp;
175 mutex_lock(&resource->lock);
176 status = acpi_evaluate_integer(resource->acpi_dev->handle, "_PAI",
178 if (!ACPI_FAILURE(status))
179 resource->avg_interval = temp;
180 mutex_unlock(&resource->lock);
182 if (ACPI_FAILURE(status)) {
183 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PAI"));
187 /* _PAI returns 0 on success, nonzero otherwise */
195 static int update_cap(struct acpi_power_meter_resource *resource)
197 unsigned long long data;
200 status = acpi_evaluate_integer(resource->acpi_dev->handle, "_GHL",
202 if (ACPI_FAILURE(status)) {
203 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _GHL"));
207 resource->cap = data;
211 static ssize_t show_cap(struct device *dev,
212 struct device_attribute *devattr,
215 struct acpi_device *acpi_dev = to_acpi_device(dev);
216 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
218 mutex_lock(&resource->lock);
219 update_cap(resource);
220 mutex_unlock(&resource->lock);
222 return sprintf(buf, "%llu\n", resource->cap * 1000);
225 static ssize_t set_cap(struct device *dev, struct device_attribute *devattr,
226 const char *buf, size_t count)
228 struct acpi_device *acpi_dev = to_acpi_device(dev);
229 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
230 union acpi_object arg0 = { ACPI_TYPE_INTEGER };
231 struct acpi_object_list args = { 1, &arg0 };
234 unsigned long long data;
237 res = kstrtoul(buf, 10, &temp);
241 temp = DIV_ROUND_CLOSEST(temp, 1000);
242 if (temp > resource->caps.max_cap || temp < resource->caps.min_cap)
244 arg0.integer.value = temp;
246 mutex_lock(&resource->lock);
247 status = acpi_evaluate_integer(resource->acpi_dev->handle, "_SHL",
249 if (!ACPI_FAILURE(status))
250 resource->cap = temp;
251 mutex_unlock(&resource->lock);
253 if (ACPI_FAILURE(status)) {
254 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _SHL"));
258 /* _SHL returns 0 on success, nonzero otherwise */
265 /* Power meter trip points */
266 static int set_acpi_trip(struct acpi_power_meter_resource *resource)
268 union acpi_object arg_objs[] = {
272 struct acpi_object_list args = { 2, arg_objs };
273 unsigned long long data;
276 /* Both trip levels must be set */
277 if (resource->trip[0] < 0 || resource->trip[1] < 0)
280 /* This driver stores min, max; ACPI wants max, min. */
281 arg_objs[0].integer.value = resource->trip[1];
282 arg_objs[1].integer.value = resource->trip[0];
284 status = acpi_evaluate_integer(resource->acpi_dev->handle, "_PTP",
286 if (ACPI_FAILURE(status)) {
287 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PTP"));
291 /* _PTP returns 0 on success, nonzero otherwise */
298 static ssize_t set_trip(struct device *dev, struct device_attribute *devattr,
299 const char *buf, size_t count)
301 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
302 struct acpi_device *acpi_dev = to_acpi_device(dev);
303 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
307 res = kstrtoul(buf, 10, &temp);
311 temp = DIV_ROUND_CLOSEST(temp, 1000);
313 mutex_lock(&resource->lock);
314 resource->trip[attr->index - 7] = temp;
315 res = set_acpi_trip(resource);
316 mutex_unlock(&resource->lock);
325 static int update_meter(struct acpi_power_meter_resource *resource)
327 unsigned long long data;
329 unsigned long local_jiffies = jiffies;
331 if (time_before(local_jiffies, resource->sensors_last_updated +
332 msecs_to_jiffies(resource->caps.sampling_time)) &&
333 resource->sensors_valid)
336 status = acpi_evaluate_integer(resource->acpi_dev->handle, "_PMM",
338 if (ACPI_FAILURE(status)) {
339 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PMM"));
343 resource->power = data;
344 resource->sensors_valid = 1;
345 resource->sensors_last_updated = jiffies;
349 static ssize_t show_power(struct device *dev,
350 struct device_attribute *devattr,
353 struct acpi_device *acpi_dev = to_acpi_device(dev);
354 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
356 mutex_lock(&resource->lock);
357 update_meter(resource);
358 mutex_unlock(&resource->lock);
360 return sprintf(buf, "%llu\n", resource->power * 1000);
364 static ssize_t show_str(struct device *dev,
365 struct device_attribute *devattr,
368 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
369 struct acpi_device *acpi_dev = to_acpi_device(dev);
370 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
373 switch (attr->index) {
375 val = resource->model_number;
378 val = resource->serial_number;
381 val = resource->oem_info;
388 return sprintf(buf, "%s\n", val);
391 static ssize_t show_val(struct device *dev,
392 struct device_attribute *devattr,
395 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
396 struct acpi_device *acpi_dev = to_acpi_device(dev);
397 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
400 switch (attr->index) {
402 val = resource->caps.min_avg_interval;
405 val = resource->caps.max_avg_interval;
408 val = resource->caps.min_cap * 1000;
411 val = resource->caps.max_cap * 1000;
414 if (resource->caps.hysteresis == UNKNOWN_HYSTERESIS)
415 return sprintf(buf, "unknown\n");
417 val = resource->caps.hysteresis * 1000;
420 if (resource->caps.flags & POWER_METER_IS_BATTERY)
426 if (resource->power > resource->cap)
433 if (resource->trip[attr->index - 7] < 0)
434 return sprintf(buf, "unknown\n");
436 val = resource->trip[attr->index - 7] * 1000;
442 return sprintf(buf, "%llu\n", val);
445 static ssize_t show_accuracy(struct device *dev,
446 struct device_attribute *devattr,
449 struct acpi_device *acpi_dev = to_acpi_device(dev);
450 struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
451 unsigned int acc = resource->caps.accuracy;
453 return sprintf(buf, "%u.%u%%\n", acc / 1000, acc % 1000);
456 static ssize_t show_name(struct device *dev,
457 struct device_attribute *devattr,
460 return sprintf(buf, "%s\n", ACPI_POWER_METER_NAME);
463 #define RO_SENSOR_TEMPLATE(_label, _show, _index) \
470 #define RW_SENSOR_TEMPLATE(_label, _show, _set, _index) \
478 /* Sensor descriptions. If you add a sensor, update NUM_SENSORS above! */
479 static struct sensor_template meter_attrs[] = {
480 RO_SENSOR_TEMPLATE(POWER_AVERAGE_NAME, show_power, 0),
481 RO_SENSOR_TEMPLATE("power1_accuracy", show_accuracy, 0),
482 RO_SENSOR_TEMPLATE("power1_average_interval_min", show_val, 0),
483 RO_SENSOR_TEMPLATE("power1_average_interval_max", show_val, 1),
484 RO_SENSOR_TEMPLATE("power1_is_battery", show_val, 5),
485 RW_SENSOR_TEMPLATE(POWER_AVG_INTERVAL_NAME, show_avg_interval,
486 set_avg_interval, 0),
490 static struct sensor_template misc_cap_attrs[] = {
491 RO_SENSOR_TEMPLATE("power1_cap_min", show_val, 2),
492 RO_SENSOR_TEMPLATE("power1_cap_max", show_val, 3),
493 RO_SENSOR_TEMPLATE("power1_cap_hyst", show_val, 4),
494 RO_SENSOR_TEMPLATE(POWER_ALARM_NAME, show_val, 6),
498 static struct sensor_template ro_cap_attrs[] = {
499 RO_SENSOR_TEMPLATE(POWER_CAP_NAME, show_cap, 0),
503 static struct sensor_template rw_cap_attrs[] = {
504 RW_SENSOR_TEMPLATE(POWER_CAP_NAME, show_cap, set_cap, 0),
508 static struct sensor_template trip_attrs[] = {
509 RW_SENSOR_TEMPLATE("power1_average_min", show_val, set_trip, 7),
510 RW_SENSOR_TEMPLATE("power1_average_max", show_val, set_trip, 8),
514 static struct sensor_template misc_attrs[] = {
515 RO_SENSOR_TEMPLATE("name", show_name, 0),
516 RO_SENSOR_TEMPLATE("power1_model_number", show_str, 0),
517 RO_SENSOR_TEMPLATE("power1_oem_info", show_str, 2),
518 RO_SENSOR_TEMPLATE("power1_serial_number", show_str, 1),
522 #undef RO_SENSOR_TEMPLATE
523 #undef RW_SENSOR_TEMPLATE
525 /* Read power domain data */
526 static void remove_domain_devices(struct acpi_power_meter_resource *resource)
530 if (!resource->num_domain_devices)
533 for (i = 0; i < resource->num_domain_devices; i++) {
534 struct acpi_device *obj = resource->domain_devices[i];
538 sysfs_remove_link(resource->holders_dir,
539 kobject_name(&obj->dev.kobj));
540 put_device(&obj->dev);
543 kfree(resource->domain_devices);
544 kobject_put(resource->holders_dir);
545 resource->num_domain_devices = 0;
548 static int read_domain_devices(struct acpi_power_meter_resource *resource)
552 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
553 union acpi_object *pss;
556 status = acpi_evaluate_object(resource->acpi_dev->handle, "_PMD", NULL,
558 if (ACPI_FAILURE(status)) {
559 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PMD"));
563 pss = buffer.pointer;
565 pss->type != ACPI_TYPE_PACKAGE) {
566 dev_err(&resource->acpi_dev->dev, ACPI_POWER_METER_NAME
567 "Invalid _PMD data\n");
572 if (!pss->package.count)
575 resource->domain_devices = kzalloc(sizeof(struct acpi_device *) *
576 pss->package.count, GFP_KERNEL);
577 if (!resource->domain_devices) {
582 resource->holders_dir = kobject_create_and_add("measures",
583 &resource->acpi_dev->dev.kobj);
584 if (!resource->holders_dir) {
589 resource->num_domain_devices = pss->package.count;
591 for (i = 0; i < pss->package.count; i++) {
592 struct acpi_device *obj;
593 union acpi_object *element = &(pss->package.elements[i]);
595 /* Refuse non-references */
596 if (element->type != ACPI_TYPE_LOCAL_REFERENCE)
599 /* Create a symlink to domain objects */
600 resource->domain_devices[i] = NULL;
601 status = acpi_bus_get_device(element->reference.handle,
602 &resource->domain_devices[i]);
603 if (ACPI_FAILURE(status))
606 obj = resource->domain_devices[i];
607 get_device(&obj->dev);
609 res = sysfs_create_link(resource->holders_dir, &obj->dev.kobj,
610 kobject_name(&obj->dev.kobj));
612 put_device(&obj->dev);
613 resource->domain_devices[i] = NULL;
621 kfree(resource->domain_devices);
623 kfree(buffer.pointer);
627 /* Registration and deregistration */
628 static int register_attrs(struct acpi_power_meter_resource *resource,
629 struct sensor_template *attrs)
631 struct device *dev = &resource->acpi_dev->dev;
632 struct sensor_device_attribute *sensors =
633 &resource->sensors[resource->num_sensors];
636 while (attrs->label) {
637 sensors->dev_attr.attr.name = attrs->label;
638 sensors->dev_attr.attr.mode = S_IRUGO;
639 sensors->dev_attr.show = attrs->show;
640 sensors->index = attrs->index;
643 sensors->dev_attr.attr.mode |= S_IWUSR;
644 sensors->dev_attr.store = attrs->set;
647 sysfs_attr_init(&sensors->dev_attr.attr);
648 res = device_create_file(dev, &sensors->dev_attr);
650 sensors->dev_attr.attr.name = NULL;
654 resource->num_sensors++;
662 static void remove_attrs(struct acpi_power_meter_resource *resource)
666 for (i = 0; i < resource->num_sensors; i++) {
667 if (!resource->sensors[i].dev_attr.attr.name)
669 device_remove_file(&resource->acpi_dev->dev,
670 &resource->sensors[i].dev_attr);
673 remove_domain_devices(resource);
675 resource->num_sensors = 0;
678 static int setup_attrs(struct acpi_power_meter_resource *resource)
682 res = read_domain_devices(resource);
686 if (resource->caps.flags & POWER_METER_CAN_MEASURE) {
687 res = register_attrs(resource, meter_attrs);
692 if (resource->caps.flags & POWER_METER_CAN_CAP) {
693 if (!can_cap_in_hardware()) {
694 dev_err(&resource->acpi_dev->dev,
695 "Ignoring unsafe software power cap!\n");
696 goto skip_unsafe_cap;
699 if (resource->caps.configurable_cap)
700 res = register_attrs(resource, rw_cap_attrs);
702 res = register_attrs(resource, ro_cap_attrs);
707 res = register_attrs(resource, misc_cap_attrs);
713 if (resource->caps.flags & POWER_METER_CAN_TRIP) {
714 res = register_attrs(resource, trip_attrs);
719 res = register_attrs(resource, misc_attrs);
725 remove_attrs(resource);
729 static void free_capabilities(struct acpi_power_meter_resource *resource)
734 str = &resource->model_number;
735 for (i = 0; i < 3; i++, str++)
739 static int read_capabilities(struct acpi_power_meter_resource *resource)
743 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
744 struct acpi_buffer state = { 0, NULL };
745 struct acpi_buffer format = { sizeof("NNNNNNNNNNN"), "NNNNNNNNNNN" };
746 union acpi_object *pss;
750 status = acpi_evaluate_object(resource->acpi_dev->handle, "_PMC", NULL,
752 if (ACPI_FAILURE(status)) {
753 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PMC"));
757 pss = buffer.pointer;
759 pss->type != ACPI_TYPE_PACKAGE ||
760 pss->package.count != 14) {
761 dev_err(&resource->acpi_dev->dev, ACPI_POWER_METER_NAME
762 "Invalid _PMC data\n");
767 /* Grab all the integer data at once */
768 state.length = sizeof(struct acpi_power_meter_capabilities);
769 state.pointer = &resource->caps;
771 status = acpi_extract_package(pss, &format, &state);
772 if (ACPI_FAILURE(status)) {
773 ACPI_EXCEPTION((AE_INFO, status, "Invalid data"));
778 if (resource->caps.units) {
779 dev_err(&resource->acpi_dev->dev, ACPI_POWER_METER_NAME
780 "Unknown units %llu.\n",
781 resource->caps.units);
786 /* Grab the string data */
787 str = &resource->model_number;
789 for (i = 11; i < 14; i++) {
790 union acpi_object *element = &(pss->package.elements[i]);
792 if (element->type != ACPI_TYPE_STRING) {
797 *str = kzalloc(sizeof(u8) * (element->string.length + 1),
804 strncpy(*str, element->string.pointer, element->string.length);
808 dev_info(&resource->acpi_dev->dev, "Found ACPI power meter.\n");
811 str = &resource->model_number;
812 for (i = 0; i < 3; i++, str++)
815 kfree(buffer.pointer);
819 /* Handle ACPI event notifications */
820 static void acpi_power_meter_notify(struct acpi_device *device, u32 event)
822 struct acpi_power_meter_resource *resource;
825 if (!device || !acpi_driver_data(device))
828 resource = acpi_driver_data(device);
830 mutex_lock(&resource->lock);
832 case METER_NOTIFY_CONFIG:
833 free_capabilities(resource);
834 res = read_capabilities(resource);
838 remove_attrs(resource);
839 setup_attrs(resource);
841 case METER_NOTIFY_TRIP:
842 sysfs_notify(&device->dev.kobj, NULL, POWER_AVERAGE_NAME);
843 update_meter(resource);
845 case METER_NOTIFY_CAP:
846 sysfs_notify(&device->dev.kobj, NULL, POWER_CAP_NAME);
847 update_cap(resource);
849 case METER_NOTIFY_INTERVAL:
850 sysfs_notify(&device->dev.kobj, NULL, POWER_AVG_INTERVAL_NAME);
851 update_avg_interval(resource);
853 case METER_NOTIFY_CAPPING:
854 sysfs_notify(&device->dev.kobj, NULL, POWER_ALARM_NAME);
855 dev_info(&device->dev, "Capping in progress.\n");
860 mutex_unlock(&resource->lock);
862 acpi_bus_generate_netlink_event(ACPI_POWER_METER_CLASS,
863 dev_name(&device->dev), event, 0);
866 static int acpi_power_meter_add(struct acpi_device *device)
869 struct acpi_power_meter_resource *resource;
874 resource = kzalloc(sizeof(struct acpi_power_meter_resource),
879 resource->sensors_valid = 0;
880 resource->acpi_dev = device;
881 mutex_init(&resource->lock);
882 strcpy(acpi_device_name(device), ACPI_POWER_METER_DEVICE_NAME);
883 strcpy(acpi_device_class(device), ACPI_POWER_METER_CLASS);
884 device->driver_data = resource;
886 free_capabilities(resource);
887 res = read_capabilities(resource);
891 resource->trip[0] = resource->trip[1] = -1;
893 res = setup_attrs(resource);
897 resource->hwmon_dev = hwmon_device_register(&device->dev);
898 if (IS_ERR(resource->hwmon_dev)) {
899 res = PTR_ERR(resource->hwmon_dev);
907 remove_attrs(resource);
914 static int acpi_power_meter_remove(struct acpi_device *device)
916 struct acpi_power_meter_resource *resource;
918 if (!device || !acpi_driver_data(device))
921 resource = acpi_driver_data(device);
922 hwmon_device_unregister(resource->hwmon_dev);
924 free_capabilities(resource);
925 remove_attrs(resource);
931 #ifdef CONFIG_PM_SLEEP
933 static int acpi_power_meter_resume(struct device *dev)
935 struct acpi_power_meter_resource *resource;
940 resource = acpi_driver_data(to_acpi_device(dev));
944 free_capabilities(resource);
945 read_capabilities(resource);
950 #endif /* CONFIG_PM_SLEEP */
952 static SIMPLE_DEV_PM_OPS(acpi_power_meter_pm, NULL, acpi_power_meter_resume);
954 static struct acpi_driver acpi_power_meter_driver = {
955 .name = "power_meter",
956 .class = ACPI_POWER_METER_CLASS,
957 .ids = power_meter_ids,
959 .add = acpi_power_meter_add,
960 .remove = acpi_power_meter_remove,
961 .notify = acpi_power_meter_notify,
963 .drv.pm = &acpi_power_meter_pm,
966 /* Module init/exit routines */
967 static int __init enable_cap_knobs(const struct dmi_system_id *d)
973 static struct dmi_system_id __initdata pm_dmi_table[] = {
975 enable_cap_knobs, "IBM Active Energy Manager",
977 DMI_MATCH(DMI_SYS_VENDOR, "IBM")
983 static int __init acpi_power_meter_init(void)
990 dmi_check_system(pm_dmi_table);
992 result = acpi_bus_register_driver(&acpi_power_meter_driver);
999 static void __exit acpi_power_meter_exit(void)
1001 acpi_bus_unregister_driver(&acpi_power_meter_driver);
1005 MODULE_DESCRIPTION("ACPI 4.0 power meter driver");
1006 MODULE_LICENSE("GPL");
1008 module_param(force_cap_on, bool, 0644);
1009 MODULE_PARM_DESC(force_cap_on, "Enable power cap even it is unsafe to do so.");
1011 module_init(acpi_power_meter_init);
1012 module_exit(acpi_power_meter_exit);