arch/powerpc/platforms/pseries/pseries_energy.c

   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
  31 static 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
  41 static 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
  71 static 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
  96 err_of_node_put:
  97         of_node_put(dn);
  98 err:
  99         if (rc)
 100                 printk(KERN_WARNING "cpu_to_drc_index(%d) failed", cpu);
 101         return ret;
 102 }
 103
 104 static 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
 130 err_of_node_put:
 131         of_node_put(dn);
 132 err:
 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
 148 static 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
 187 static 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
 210 static 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
 216 static 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
 222 static 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
 228 static 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
 244 struct device_attribute attr_cpu_activate_hint_list =
 245                 __ATTR(pseries_activate_hint_list, 0444,
 246                 cpu_activate_hint_list_show, NULL);
 247
 248 struct device_attribute attr_cpu_deactivate_hint_list =
 249                 __ATTR(pseries_deactivate_hint_list, 0444,
 250                 cpu_deactivate_hint_list_show, NULL);
 251
 252 struct device_attribute attr_percpu_activate_hint =
 253                 __ATTR(pseries_activate_hint, 0444,
 254                 percpu_activate_hint_show, NULL);
 255
 256 struct device_attribute attr_percpu_deactivate_hint =
 257                 __ATTR(pseries_deactivate_hint, 0444,
 258                 percpu_deactivate_hint_show, NULL);
 259
 260 static 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
 298 static 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
 319 module_init(pseries_energy_init);
 320 module_exit(pseries_energy_cleanup);
 321 MODULE_DESCRIPTION("Driver for pSeries platform energy management");
 322 MODULE_AUTHOR("Vaidyanathan Srinivasan");
 323 MODULE_LICENSE("GPL");