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 #include <asm/firmware.h>
  25
  26
  27 #define MODULE_VERS "1.0"
  28 #define MODULE_NAME "pseries_energy"
  29
  30 /* Driver flags */
  31
  32 static int sysfs_entries;
  33
  34 /* Helper routines */
  35
  36 /* Helper Routines to convert between drc_index to cpu numbers */
  37
  38 static u32 cpu_to_drc_index(int cpu)
  39 {
  40         struct device_node *dn = NULL;
  41         const int *indexes;
  42         int i;
  43         int rc = 1;
  44         u32 ret = 0;
  45
  46         dn = of_find_node_by_path("/cpus");
  47         if (dn == NULL)
  48                 goto err;
  49         indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
  50         if (indexes == NULL)
  51                 goto err_of_node_put;
  52         /* Convert logical cpu number to core number */
  53         i = cpu_core_index_of_thread(cpu);
  54         /*
  55          * The first element indexes[0] is the number of drc_indexes
  56          * returned in the list.  Hence i+1 will get the drc_index
  57          * corresponding to core number i.
  58          */
  59         WARN_ON(i > indexes[0]);
  60         ret = indexes[i + 1];
  61         rc = 0;
  62
  63 err_of_node_put:
  64         of_node_put(dn);
  65 err:
  66         if (rc)
  67                 printk(KERN_WARNING "cpu_to_drc_index(%d) failed", cpu);
  68         return ret;
  69 }
  70
  71 static int drc_index_to_cpu(u32 drc_index)
  72 {
  73         struct device_node *dn = NULL;
  74         const int *indexes;
  75         int i, cpu = 0;
  76         int rc = 1;
  77
  78         dn = of_find_node_by_path("/cpus");
  79         if (dn == NULL)
  80                 goto err;
  81         indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
  82         if (indexes == NULL)
  83                 goto err_of_node_put;
  84         /*
  85          * First element in the array is the number of drc_indexes
  86          * returned.  Search through the list to find the matching
  87          * drc_index and get the core number
  88          */
  89         for (i = 0; i < indexes[0]; i++) {
  90                 if (indexes[i + 1] == drc_index)
  91                         break;
  92         }
  93         /* Convert core number to logical cpu number */
  94         cpu = cpu_first_thread_of_core(i);
  95         rc = 0;
  96
  97 err_of_node_put:
  98         of_node_put(dn);
  99 err:
 100         if (rc)
 101                 printk(KERN_WARNING "drc_index_to_cpu(%d) failed", drc_index);
 102         return cpu;
 103 }
 104
 105 /*
 106  * pseries hypervisor call H_BEST_ENERGY provides hints to OS on
 107  * preferred logical cpus to activate or deactivate for optimized
 108  * energy consumption.
 109  */
 110
 111 #define FLAGS_MODE1     0x004E200000080E01
 112 #define FLAGS_MODE2     0x004E200000080401
 113 #define FLAGS_ACTIVATE  0x100
 114
 115 static ssize_t get_best_energy_list(char *page, int activate)
 116 {
 117         int rc, cnt, i, cpu;
 118         unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
 119         unsigned long flags = 0;
 120         u32 *buf_page;
 121         char *s = page;
 122
 123         buf_page = (u32 *) get_zeroed_page(GFP_KERNEL);
 124         if (!buf_page)
 125                 return -ENOMEM;
 126
 127         flags = FLAGS_MODE1;
 128         if (activate)
 129                 flags |= FLAGS_ACTIVATE;
 130
 131         rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags, 0, __pa(buf_page),
 132                                 0, 0, 0, 0, 0, 0);
 133         if (rc != H_SUCCESS) {
 134                 free_page((unsigned long) buf_page);
 135                 return -EINVAL;
 136         }
 137
 138         cnt = retbuf[0];
 139         for (i = 0; i < cnt; i++) {
 140                 cpu = drc_index_to_cpu(buf_page[2*i+1]);
 141                 if ((cpu_online(cpu) && !activate) ||
 142                     (!cpu_online(cpu) && activate))
 143                         s += sprintf(s, "%d,", cpu);
 144         }
 145         if (s > page) { /* Something to show */
 146                 s--; /* Suppress last comma */
 147                 s += sprintf(s, "\n");
 148         }
 149
 150         free_page((unsigned long) buf_page);
 151         return s-page;
 152 }
 153
 154 static ssize_t get_best_energy_data(struct device *dev,
 155                                         char *page, int activate)
 156 {
 157         int rc;
 158         unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
 159         unsigned long flags = 0;
 160
 161         flags = FLAGS_MODE2;
 162         if (activate)
 163                 flags |= FLAGS_ACTIVATE;
 164
 165         rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags,
 166                                 cpu_to_drc_index(dev->id),
 167                                 0, 0, 0, 0, 0, 0, 0);
 168
 169         if (rc != H_SUCCESS)
 170                 return -EINVAL;
 171
 172         return sprintf(page, "%lu\n", retbuf[1] >> 32);
 173 }
 174
 175 /* Wrapper functions */
 176
 177 static ssize_t cpu_activate_hint_list_show(struct device *dev,
 178                         struct device_attribute *attr, char *page)
 179 {
 180         return get_best_energy_list(page, 1);
 181 }
 182
 183 static ssize_t cpu_deactivate_hint_list_show(struct device *dev,
 184                         struct device_attribute *attr, char *page)
 185 {
 186         return get_best_energy_list(page, 0);
 187 }
 188
 189 static ssize_t percpu_activate_hint_show(struct device *dev,
 190                         struct device_attribute *attr, char *page)
 191 {
 192         return get_best_energy_data(dev, page, 1);
 193 }
 194
 195 static ssize_t percpu_deactivate_hint_show(struct device *dev,
 196                         struct device_attribute *attr, char *page)
 197 {
 198         return get_best_energy_data(dev, page, 0);
 199 }
 200
 201 /*
 202  * Create sysfs interface:
 203  * /sys/devices/system/cpu/pseries_activate_hint_list
 204  * /sys/devices/system/cpu/pseries_deactivate_hint_list
 205  *      Comma separated list of cpus to activate or deactivate
 206  * /sys/devices/system/cpu/cpuN/pseries_activate_hint
 207  * /sys/devices/system/cpu/cpuN/pseries_deactivate_hint
 208  *      Per-cpu value of the hint
 209  */
 210
 211 struct device_attribute attr_cpu_activate_hint_list =
 212                 __ATTR(pseries_activate_hint_list, 0444,
 213                 cpu_activate_hint_list_show, NULL);
 214
 215 struct device_attribute attr_cpu_deactivate_hint_list =
 216                 __ATTR(pseries_deactivate_hint_list, 0444,
 217                 cpu_deactivate_hint_list_show, NULL);
 218
 219 struct device_attribute attr_percpu_activate_hint =
 220                 __ATTR(pseries_activate_hint, 0444,
 221                 percpu_activate_hint_show, NULL);
 222
 223 struct device_attribute attr_percpu_deactivate_hint =
 224                 __ATTR(pseries_deactivate_hint, 0444,
 225                 percpu_deactivate_hint_show, NULL);
 226
 227 static int __init pseries_energy_init(void)
 228 {
 229         int cpu, err;
 230         struct device *cpu_dev;
 231
 232         if (!firmware_has_feature(FW_FEATURE_BEST_ENERGY)) {
 233                 printk(KERN_INFO "Hypercall H_BEST_ENERGY not supported\n");
 234                 return 0;
 235         }
 236         /* Create the sysfs files */
 237         err = device_create_file(cpu_subsys.dev_root,
 238                                 &attr_cpu_activate_hint_list);
 239         if (!err)
 240                 err = device_create_file(cpu_subsys.dev_root,
 241                                 &attr_cpu_deactivate_hint_list);
 242
 243         if (err)
 244                 return err;
 245         for_each_possible_cpu(cpu) {
 246                 cpu_dev = get_cpu_device(cpu);
 247                 err = device_create_file(cpu_dev,
 248                                 &attr_percpu_activate_hint);
 249                 if (err)
 250                         break;
 251                 err = device_create_file(cpu_dev,
 252                                 &attr_percpu_deactivate_hint);
 253                 if (err)
 254                         break;
 255         }
 256
 257         if (err)
 258                 return err;
 259
 260         sysfs_entries = 1; /* Removed entries on cleanup */
 261         return 0;
 262
 263 }
 264
 265 static void __exit pseries_energy_cleanup(void)
 266 {
 267         int cpu;
 268         struct device *cpu_dev;
 269
 270         if (!sysfs_entries)
 271                 return;
 272
 273         /* Remove the sysfs files */
 274         device_remove_file(cpu_subsys.dev_root, &attr_cpu_activate_hint_list);
 275         device_remove_file(cpu_subsys.dev_root, &attr_cpu_deactivate_hint_list);
 276
 277         for_each_possible_cpu(cpu) {
 278                 cpu_dev = get_cpu_device(cpu);
 279                 sysfs_remove_file(&cpu_dev->kobj,
 280                                 &attr_percpu_activate_hint.attr);
 281                 sysfs_remove_file(&cpu_dev->kobj,
 282                                 &attr_percpu_deactivate_hint.attr);
 283         }
 284 }
 285
 286 module_init(pseries_energy_init);
 287 module_exit(pseries_energy_cleanup);
 288 MODULE_DESCRIPTION("Driver for pSeries platform energy management");
 289 MODULE_AUTHOR("Vaidyanathan Srinivasan");
 290 MODULE_LICENSE("GPL");