2 * POWER platform energy management driver
3 * Copyright (C) 2010 IBM Corporation
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * version 2 as published by the Free Software Foundation.
9 * This pseries platform device driver provides access to
10 * platform energy management capabilities.
13 #include <linux/module.h>
14 #include <linux/types.h>
15 #include <linux/errno.h>
16 #include <linux/init.h>
17 #include <linux/seq_file.h>
18 #include <linux/sysdev.h>
19 #include <linux/cpu.h>
21 #include <asm/cputhreads.h>
23 #include <asm/hvcall.h>
26 #define MODULE_VERS "1.0"
27 #define MODULE_NAME "pseries_energy"
31 static int sysfs_entries;
36 * Routine to detect firmware support for hcall
37 * return 1 if H_BEST_ENERGY is supported
41 static int check_for_h_best_energy(void)
43 struct device_node *rtas = NULL;
44 const char *hypertas, *s;
48 rtas = of_find_node_by_path("/rtas");
52 hypertas = of_get_property(rtas, "ibm,hypertas-functions", &length);
58 /* hypertas will have list of strings with hcall names */
59 for (s = hypertas; s < hypertas + length; s += strlen(s) + 1) {
60 if (!strncmp("hcall-best-energy-1", s, 19)) {
61 rc = 1; /* Found the string */
69 /* Helper Routines to convert between drc_index to cpu numbers */
71 static u32 cpu_to_drc_index(int cpu)
73 struct device_node *dn = NULL;
79 dn = of_find_node_by_path("/cpus");
82 indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
85 /* Convert logical cpu number to core number */
86 i = cpu_core_index_of_thread(cpu);
88 * The first element indexes[0] is the number of drc_indexes
89 * returned in the list. Hence i+1 will get the drc_index
90 * corresponding to core number i.
92 WARN_ON(i > indexes[0]);
100 printk(KERN_WARNING "cpu_to_drc_index(%d) failed", cpu);
104 static int drc_index_to_cpu(u32 drc_index)
106 struct device_node *dn = NULL;
111 dn = of_find_node_by_path("/cpus");
114 indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
116 goto err_of_node_put;
118 * First element in the array is the number of drc_indexes
119 * returned. Search through the list to find the matching
120 * drc_index and get the core number
122 for (i = 0; i < indexes[0]; i++) {
123 if (indexes[i + 1] == drc_index)
126 /* Convert core number to logical cpu number */
127 cpu = cpu_first_thread_of_core(i);
134 printk(KERN_WARNING "drc_index_to_cpu(%d) failed", drc_index);
139 * pseries hypervisor call H_BEST_ENERGY provides hints to OS on
140 * preferred logical cpus to activate or deactivate for optimized
141 * energy consumption.
144 #define FLAGS_MODE1 0x004E200000080E01
145 #define FLAGS_MODE2 0x004E200000080401
146 #define FLAGS_ACTIVATE 0x100
148 static ssize_t get_best_energy_list(char *page, int activate)
151 unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
152 unsigned long flags = 0;
156 buf_page = (u32 *) get_zeroed_page(GFP_KERNEL);
162 flags |= FLAGS_ACTIVATE;
164 rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags, 0, __pa(buf_page),
166 if (rc != H_SUCCESS) {
167 free_page((unsigned long) buf_page);
172 for (i = 0; i < cnt; i++) {
173 cpu = drc_index_to_cpu(buf_page[2*i+1]);
174 if ((cpu_online(cpu) && !activate) ||
175 (!cpu_online(cpu) && activate))
176 s += sprintf(s, "%d,", cpu);
178 if (s > page) { /* Something to show */
179 s--; /* Suppress last comma */
180 s += sprintf(s, "\n");
183 free_page((unsigned long) buf_page);
187 static ssize_t get_best_energy_data(struct sys_device *dev,
188 char *page, int activate)
191 unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
192 unsigned long flags = 0;
196 flags |= FLAGS_ACTIVATE;
198 rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags,
199 cpu_to_drc_index(dev->id),
200 0, 0, 0, 0, 0, 0, 0);
205 return sprintf(page, "%lu\n", retbuf[1] >> 32);
208 /* Wrapper functions */
210 static ssize_t cpu_activate_hint_list_show(struct sysdev_class *class,
211 struct sysdev_class_attribute *attr, char *page)
213 return get_best_energy_list(page, 1);
216 static ssize_t cpu_deactivate_hint_list_show(struct sysdev_class *class,
217 struct sysdev_class_attribute *attr, char *page)
219 return get_best_energy_list(page, 0);
222 static ssize_t percpu_activate_hint_show(struct sys_device *dev,
223 struct sysdev_attribute *attr, char *page)
225 return get_best_energy_data(dev, page, 1);
228 static ssize_t percpu_deactivate_hint_show(struct sys_device *dev,
229 struct sysdev_attribute *attr, char *page)
231 return get_best_energy_data(dev, page, 0);
235 * Create sysfs interface:
236 * /sys/devices/system/cpu/pseries_activate_hint_list
237 * /sys/devices/system/cpu/pseries_deactivate_hint_list
238 * Comma separated list of cpus to activate or deactivate
239 * /sys/devices/system/cpu/cpuN/pseries_activate_hint
240 * /sys/devices/system/cpu/cpuN/pseries_deactivate_hint
241 * Per-cpu value of the hint
244 struct sysdev_class_attribute attr_cpu_activate_hint_list =
245 _SYSDEV_CLASS_ATTR(pseries_activate_hint_list, 0444,
246 cpu_activate_hint_list_show, NULL);
248 struct sysdev_class_attribute attr_cpu_deactivate_hint_list =
249 _SYSDEV_CLASS_ATTR(pseries_deactivate_hint_list, 0444,
250 cpu_deactivate_hint_list_show, NULL);
252 struct sysdev_attribute attr_percpu_activate_hint =
253 _SYSDEV_ATTR(pseries_activate_hint, 0444,
254 percpu_activate_hint_show, NULL);
256 struct sysdev_attribute attr_percpu_deactivate_hint =
257 _SYSDEV_ATTR(pseries_deactivate_hint, 0444,
258 percpu_deactivate_hint_show, NULL);
260 static int __init pseries_energy_init(void)
263 struct sys_device *cpu_sys_dev;
265 if (!check_for_h_best_energy()) {
266 printk(KERN_INFO "Hypercall H_BEST_ENERGY not supported\n");
269 /* Create the sysfs files */
270 err = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
271 &attr_cpu_activate_hint_list.attr);
273 err = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
274 &attr_cpu_deactivate_hint_list.attr);
278 for_each_possible_cpu(cpu) {
279 cpu_sys_dev = get_cpu_sysdev(cpu);
280 err = sysfs_create_file(&cpu_sys_dev->kobj,
281 &attr_percpu_activate_hint.attr);
284 err = sysfs_create_file(&cpu_sys_dev->kobj,
285 &attr_percpu_deactivate_hint.attr);
293 sysfs_entries = 1; /* Removed entries on cleanup */
298 static void __exit pseries_energy_cleanup(void)
301 struct sys_device *cpu_sys_dev;
306 /* Remove the sysfs files */
307 sysfs_remove_file(&cpu_sysdev_class.kset.kobj,
308 &attr_cpu_activate_hint_list.attr);
310 sysfs_remove_file(&cpu_sysdev_class.kset.kobj,
311 &attr_cpu_deactivate_hint_list.attr);
313 for_each_possible_cpu(cpu) {
314 cpu_sys_dev = get_cpu_sysdev(cpu);
315 sysfs_remove_file(&cpu_sys_dev->kobj,
316 &attr_percpu_activate_hint.attr);
317 sysfs_remove_file(&cpu_sys_dev->kobj,
318 &attr_percpu_deactivate_hint.attr);
322 module_init(pseries_energy_init);
323 module_exit(pseries_energy_cleanup);
324 MODULE_DESCRIPTION("Driver for pSeries platform energy management");
325 MODULE_AUTHOR("Vaidyanathan Srinivasan");
326 MODULE_LICENSE("GPL");