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1/*
2 * POWER platform energy management driver
3 * Copyright (C) 2010 IBM Corporation
4 *
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.
8 *
9 * This pseries platform device driver provides access to
10 * platform energy management capabilities.
11 */
12
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/device.h>
19#include <linux/cpu.h>
20#include <linux/of.h>
21#include <asm/cputhreads.h>
22#include <asm/page.h>
23#include <asm/hvcall.h>
24
25
26#define MODULE_VERS "1.0"
27#define MODULE_NAME "pseries_energy"
28
29/* Driver flags */
30
31static int sysfs_entries;
32
33/* Helper routines */
34
35/*
36 * Routine to detect firmware support for hcall
37 * return 1 if H_BEST_ENERGY is supported
38 * else return 0
39 */
40
41static int check_for_h_best_energy(void)
42{
43 struct device_node *rtas = NULL;
44 const char *hypertas, *s;
45 int length;
46 int rc = 0;
47
48 rtas = of_find_node_by_path("/rtas");
49 if (!rtas)
50 return 0;
51
52 hypertas = of_get_property(rtas, "ibm,hypertas-functions", &length);
53 if (!hypertas) {
54 of_node_put(rtas);
55 return 0;
56 }
57
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 */
62 break;
63 }
64 }
65 of_node_put(rtas);
66 return rc;
67}
68
69/* Helper Routines to convert between drc_index to cpu numbers */
70
71static u32 cpu_to_drc_index(int cpu)
72{
73 struct device_node *dn = NULL;
74 const int *indexes;
75 int i;
76 int rc = 1;
77 u32 ret = 0;
78
79 dn = of_find_node_by_path("/cpus");
80 if (dn == NULL)
81 goto err;
82 indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
83 if (indexes == NULL)
84 goto err_of_node_put;
85 /* Convert logical cpu number to core number */
86 i = cpu_core_index_of_thread(cpu);
87 /*
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.
91 */
92 WARN_ON(i > indexes[0]);
93 ret = indexes[i + 1];
94 rc = 0;
95
96err_of_node_put:
97 of_node_put(dn);
98err:
99 if (rc)
100 printk(KERN_WARNING "cpu_to_drc_index(%d) failed", cpu);
101 return ret;
102}
103
104static int drc_index_to_cpu(u32 drc_index)
105{
106 struct device_node *dn = NULL;
107 const int *indexes;
108 int i, cpu = 0;
109 int rc = 1;
110
111 dn = of_find_node_by_path("/cpus");
112 if (dn == NULL)
113 goto err;
114 indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
115 if (indexes == NULL)
116 goto err_of_node_put;
117 /*
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
121 */
122 for (i = 0; i < indexes[0]; i++) {
123 if (indexes[i + 1] == drc_index)
124 break;
125 }
126 /* Convert core number to logical cpu number */
127 cpu = cpu_first_thread_of_core(i);
128 rc = 0;
129
130err_of_node_put:
131 of_node_put(dn);
132err:
133 if (rc)
134 printk(KERN_WARNING "drc_index_to_cpu(%d) failed", drc_index);
135 return cpu;
136}
137
138/*
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.
142 */
143
144#define FLAGS_MODE1 0x004E200000080E01
145#define FLAGS_MODE2 0x004E200000080401
146#define FLAGS_ACTIVATE 0x100
147
148static ssize_t get_best_energy_list(char *page, int activate)
149{
150 int rc, cnt, i, cpu;
151 unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
152 unsigned long flags = 0;
153 u32 *buf_page;
154 char *s = page;
155
156 buf_page = (u32 *) get_zeroed_page(GFP_KERNEL);
157 if (!buf_page)
158 return -ENOMEM;
159
160 flags = FLAGS_MODE1;
161 if (activate)
162 flags |= FLAGS_ACTIVATE;
163
164 rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags, 0, __pa(buf_page),
165 0, 0, 0, 0, 0, 0);
166 if (rc != H_SUCCESS) {
167 free_page((unsigned long) buf_page);
168 return -EINVAL;
169 }
170
171 cnt = retbuf[0];
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);
177 }
178 if (s > page) { /* Something to show */
179 s--; /* Suppress last comma */
180 s += sprintf(s, "\n");
181 }
182
183 free_page((unsigned long) buf_page);
184 return s-page;
185}
186
187static ssize_t get_best_energy_data(struct device *dev,
188 char *page, int activate)
189{
190 int rc;
191 unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
192 unsigned long flags = 0;
193
194 flags = FLAGS_MODE2;
195 if (activate)
196 flags |= FLAGS_ACTIVATE;
197
198 rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags,
199 cpu_to_drc_index(dev->id),
200 0, 0, 0, 0, 0, 0, 0);
201
202 if (rc != H_SUCCESS)
203 return -EINVAL;
204
205 return sprintf(page, "%lu\n", retbuf[1] >> 32);
206}
207
208/* Wrapper functions */
209
210static ssize_t cpu_activate_hint_list_show(struct device *dev,
211 struct device_attribute *attr, char *page)
212{
213 return get_best_energy_list(page, 1);
214}
215
216static ssize_t cpu_deactivate_hint_list_show(struct device *dev,
217 struct device_attribute *attr, char *page)
218{
219 return get_best_energy_list(page, 0);
220}
221
222static ssize_t percpu_activate_hint_show(struct device *dev,
223 struct device_attribute *attr, char *page)
224{
225 return get_best_energy_data(dev, page, 1);
226}
227
228static ssize_t percpu_deactivate_hint_show(struct device *dev,
229 struct device_attribute *attr, char *page)
230{
231 return get_best_energy_data(dev, page, 0);
232}
233
234/*
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
242 */
243
244struct device_attribute attr_cpu_activate_hint_list =
245 __ATTR(pseries_activate_hint_list, 0444,
246 cpu_activate_hint_list_show, NULL);
247
248struct device_attribute attr_cpu_deactivate_hint_list =
249 __ATTR(pseries_deactivate_hint_list, 0444,
250 cpu_deactivate_hint_list_show, NULL);
251
252struct device_attribute attr_percpu_activate_hint =
253 __ATTR(pseries_activate_hint, 0444,
254 percpu_activate_hint_show, NULL);
255
256struct device_attribute attr_percpu_deactivate_hint =
257 __ATTR(pseries_deactivate_hint, 0444,
258 percpu_deactivate_hint_show, NULL);
259
260static int __init pseries_energy_init(void)
261{
262 int cpu, err;
263 struct device *cpu_dev;
264
265 if (!check_for_h_best_energy()) {
266 printk(KERN_INFO "Hypercall H_BEST_ENERGY not supported\n");
267 return 0;
268 }
269 /* Create the sysfs files */
270 err = device_create_file(cpu_subsys.dev_root,
271 &attr_cpu_activate_hint_list);
272 if (!err)
273 err = device_create_file(cpu_subsys.dev_root,
274 &attr_cpu_deactivate_hint_list);
275
276 if (err)
277 return err;
278 for_each_possible_cpu(cpu) {
279 cpu_dev = get_cpu_device(cpu);
280 err = device_create_file(cpu_dev,
281 &attr_percpu_activate_hint);
282 if (err)
283 break;
284 err = device_create_file(cpu_dev,
285 &attr_percpu_deactivate_hint);
286 if (err)
287 break;
288 }
289
290 if (err)
291 return err;
292
293 sysfs_entries = 1; /* Removed entries on cleanup */
294 return 0;
295
296}
297
298static void __exit pseries_energy_cleanup(void)
299{
300 int cpu;
301 struct device *cpu_dev;
302
303 if (!sysfs_entries)
304 return;
305
306 /* Remove the sysfs files */
307 device_remove_file(cpu_subsys.dev_root, &attr_cpu_activate_hint_list);
308 device_remove_file(cpu_subsys.dev_root, &attr_cpu_deactivate_hint_list);
309
310 for_each_possible_cpu(cpu) {
311 cpu_dev = get_cpu_device(cpu);
312 sysfs_remove_file(&cpu_dev->kobj,
313 &attr_percpu_activate_hint.attr);
314 sysfs_remove_file(&cpu_dev->kobj,
315 &attr_percpu_deactivate_hint.attr);
316 }
317}
318
319module_init(pseries_energy_init);
320module_exit(pseries_energy_cleanup);
321MODULE_DESCRIPTION("Driver for pSeries platform energy management");
322MODULE_AUTHOR("Vaidyanathan Srinivasan");
323MODULE_LICENSE("GPL");