arch/powerpc/platforms/cell/cbe_cpufreq.c

   1 /*
   2  * cpufreq driver for the cell processor
   3  *
   4  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
   5  *
   6  * Author: Christian Krafft <krafft@de.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #include <linux/cpufreq.h>
  24 #include <linux/timer.h>
  25
  26 #include <asm/hw_irq.h>
  27 #include <asm/io.h>
  28 #include <asm/machdep.h>
  29 #include <asm/processor.h>
  30 #include <asm/prom.h>
  31 #include <asm/time.h>
  32 #include <asm/pmi.h>
  33 #include <asm/of_platform.h>
  34
  35 #include "cbe_regs.h"
  36
  37 static DEFINE_MUTEX(cbe_switch_mutex);
  38
  39
  40 /* the CBE supports an 8 step frequency scaling */
  41 static struct cpufreq_frequency_table cbe_freqs[] = {
  42         {1,     0},
  43         {2,     0},
  44         {3,     0},
  45         {4,     0},
  46         {5,     0},
  47         {6,     0},
  48         {8,     0},
  49         {10,    0},
  50         {0,     CPUFREQ_TABLE_END},
  51 };
  52
  53 /* to write to MIC register */
  54 static u64 MIC_Slow_Fast_Timer_table[] = {
  55         [0 ... 7] = 0x007fc00000000000ull,
  56 };
  57
  58 /* more values for the MIC */
  59 static u64 MIC_Slow_Next_Timer_table[] = {
  60         0x0000240000000000ull,
  61         0x0000268000000000ull,
  62         0x000029C000000000ull,
  63         0x00002D0000000000ull,
  64         0x0000300000000000ull,
  65         0x0000334000000000ull,
  66         0x000039C000000000ull,
  67         0x00003FC000000000ull,
  68 };
  69
  70 static u8 pmi_slow_mode_limit[MAX_BE];
  71
  72 /*
  73  * hardware specific functions
  74  */
  75
  76 static bool cbe_cpufreq_has_pmi;
  77
  78 #ifdef CONFIG_PPC_PMI
  79 static int set_pmode_pmi(int cpu, unsigned int pmode)
  80 {
  81         int ret;
  82         pmi_message_t pmi_msg;
  83 #ifdef DEBUG
  84         long time;
  85 #endif
  86
  87         pmi_msg.type = PMI_TYPE_FREQ_CHANGE;
  88         pmi_msg.data1 = cbe_cpu_to_node(cpu);
  89         pmi_msg.data2 = pmode;
  90
  91 #ifdef DEBUG
  92         time = jiffies;
  93 #endif
  94
  95         pmi_send_message(pmi_msg);
  96         ret = pmi_msg.data2;
  97
  98         pr_debug("PMI returned slow mode %d\n", ret);
  99
 100 #ifdef DEBUG
 101         time = jiffies - time; /* actual cycles (not cpu cycles!) */
 102         time = jiffies_to_msecs(time);
 103         pr_debug("had to wait %lu ms for a transition using PMI.\n", time);
 104 #endif
 105         return ret;
 106 }
 107 #endif
 108
 109 static int get_pmode(int cpu)
 110 {
 111         int ret;
 112         struct cbe_pmd_regs __iomem *pmd_regs;
 113
 114         pmd_regs = cbe_get_cpu_pmd_regs(cpu);
 115         ret = in_be64(&pmd_regs->pmsr) & 0x07;
 116
 117         return ret;
 118 }
 119
 120 static int set_pmode_reg(int cpu, unsigned int pmode)
 121 {
 122         struct cbe_pmd_regs __iomem *pmd_regs;
 123         struct cbe_mic_tm_regs __iomem *mic_tm_regs;
 124         u64 flags;
 125         u64 value;
 126 #ifdef DEBUG
 127         long time;
 128 #endif
 129
 130         local_irq_save(flags);
 131
 132         mic_tm_regs = cbe_get_cpu_mic_tm_regs(cpu);
 133         pmd_regs = cbe_get_cpu_pmd_regs(cpu);
 134
 135 #ifdef DEBUG
 136         time = jiffies;
 137 #endif
 138         out_be64(&mic_tm_regs->slow_fast_timer_0, MIC_Slow_Fast_Timer_table[pmode]);
 139         out_be64(&mic_tm_regs->slow_fast_timer_1, MIC_Slow_Fast_Timer_table[pmode]);
 140
 141         out_be64(&mic_tm_regs->slow_next_timer_0, MIC_Slow_Next_Timer_table[pmode]);
 142         out_be64(&mic_tm_regs->slow_next_timer_1, MIC_Slow_Next_Timer_table[pmode]);
 143
 144         value = in_be64(&pmd_regs->pmcr);
 145         /* set bits to zero */
 146         value &= 0xFFFFFFFFFFFFFFF8ull;
 147         /* set bits to next pmode */
 148         value |= pmode;
 149
 150         out_be64(&pmd_regs->pmcr, value);
 151
 152 #ifdef DEBUG
 153         /* wait until new pmode appears in status register */
 154         value = in_be64(&pmd_regs->pmsr) & 0x07;
 155         while(value != pmode) {
 156                 cpu_relax();
 157                 value = in_be64(&pmd_regs->pmsr) & 0x07;
 158         }
 159
 160         time = jiffies - time;
 161         time = jiffies_to_msecs(time);
 162         pr_debug("had to wait %lu ms for a transition using " \
 163                  "the pervasive unit.\n", time);
 164 #endif
 165         local_irq_restore(flags);
 166
 167         return 0;
 168 }
 169
 170 static int set_pmode(int cpu, unsigned int slow_mode)
 171 {
 172         int rc;
 173 #ifdef CONFIG_PPC_PMI
 174         if (cbe_cpufreq_has_pmi)
 175                 rc = set_pmode_pmi(cpu, slow_mode);
 176         else
 177 #endif
 178                 rc = set_pmode_reg(cpu, slow_mode);
 179
 180         pr_debug("register contains slow mode %d\n", get_pmode(cpu));
 181
 182         return rc;
 183 }
 184
 185 static void cbe_cpufreq_handle_pmi(pmi_message_t pmi_msg)
 186 {
 187         u8 node; slow_mode;
 188
 189         BUG_ON(pmi_msg.type != PMI_TYPE_FREQ_CHANGE);
 190
 191         node = pmi_msg.data1;
 192         slow_mode = pmi_msg.data2;
 193
 194         pmi_slow_mode_limit[node] = slow_mode;
 195
 196         pr_debug("cbe_handle_pmi: node: %d, max slow_mode=%d\n", slow_mode);
 197 }
 198
 199 static int pmi_notifier(struct notifier_block *nb,
 200                                        unsigned long event, void *data)
 201 {
 202         struct cpufreq_policy *policy = data;
 203         u8 node;
 204
 205         node = cbe_cpu_to_node(policy->cpu);
 206
 207         pr_debug("got notified, event=%lu, node=%u\n", event, node);
 208
 209         if (pmi_slow_mode_limit[node] != 0) {
 210                 pr_debug("limiting node %d to slow mode %d\n",
 211                          node, pmi_slow_mode_limit[node]);
 212
 213                 cpufreq_verify_within_limits(policy, 0,
 214                          cbe_freqs[pmi_slow_mode_limit[node]].frequency);
 215         }
 216
 217         return 0;
 218 }
 219
 220 static struct notifier_block pmi_notifier_block = {
 221         .notifier_call = pmi_notifier,
 222 };
 223
 224 static struct pmi_handler cbe_pmi_handler = {
 225         .type                   = PMI_TYPE_FREQ_CHANGE,
 226         .handle_pmi_message     = cbe_cpufreq_handle_pmi,
 227 };
 228
 229
 230 /*
 231  * cpufreq functions
 232  */
 233
 234 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
 235 {
 236         const u32 *max_freqp;
 237         u32 max_freq;
 238         int i, cur_pmode;
 239         struct device_node *cpu;
 240
 241         cpu = of_get_cpu_node(policy->cpu, NULL);
 242
 243         if (!cpu)
 244                 return -ENODEV;
 245
 246         pr_debug("init cpufreq on CPU %d\n", policy->cpu);
 247
 248         max_freqp = of_get_property(cpu, "clock-frequency", NULL);
 249
 250         of_node_put(cpu);
 251
 252         if (!max_freqp)
 253                 return -EINVAL;
 254
 255         /* we need the freq in kHz */
 256         max_freq = *max_freqp / 1000;
 257
 258         pr_debug("max clock-frequency is at %u kHz\n", max_freq);
 259         pr_debug("initializing frequency table\n");
 260
 261         /* initialize frequency table */
 262         for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
 263                 cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index;
 264                 pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
 265         }
 266
 267         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 268
 269         /* if DEBUG is enabled set_pmode() measures the latency
 270          * of a transition */
 271         policy->cpuinfo.transition_latency = 25000;
 272
 273         cur_pmode = get_pmode(policy->cpu);
 274         pr_debug("current pmode is at %d\n",cur_pmode);
 275
 276         policy->cur = cbe_freqs[cur_pmode].frequency;
 277
 278 #ifdef CONFIG_SMP
 279         policy->cpus = cpu_sibling_map[policy->cpu];
 280 #endif
 281
 282         cpufreq_frequency_table_get_attr(cbe_freqs, policy->cpu);
 283
 284         /* this ensures that policy->cpuinfo_min
 285          * and policy->cpuinfo_max are set correctly */
 286         return cpufreq_frequency_table_cpuinfo(policy, cbe_freqs);
 287 }
 288
 289 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 290 {
 291         cpufreq_frequency_table_put_attr(policy->cpu);
 292         return 0;
 293 }
 294
 295 static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
 296 {
 297         return cpufreq_frequency_table_verify(policy, cbe_freqs);
 298 }
 299
 300
 301 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
 302                               unsigned int target_freq,
 303                               unsigned int relation)
 304 {
 305         int rc;
 306         struct cpufreq_freqs freqs;
 307         unsigned int cbe_pmode_new;
 308
 309         cpufreq_frequency_table_target(policy,
 310                                        cbe_freqs,
 311                                        target_freq,
 312                                        relation,
 313                                        &cbe_pmode_new);
 314
 315         freqs.old = policy->cur;
 316         freqs.new = cbe_freqs[cbe_pmode_new].frequency;
 317         freqs.cpu = policy->cpu;
 318
 319         mutex_lock(&cbe_switch_mutex);
 320         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 321
 322         pr_debug("setting frequency for cpu %d to %d kHz, " \
 323                  "1/%d of max frequency\n",
 324                  policy->cpu,
 325                  cbe_freqs[cbe_pmode_new].frequency,
 326                  cbe_freqs[cbe_pmode_new].index);
 327
 328         rc = set_pmode(policy->cpu, cbe_pmode_new);
 329
 330         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 331         mutex_unlock(&cbe_switch_mutex);
 332
 333         return rc;
 334 }
 335
 336 static struct cpufreq_driver cbe_cpufreq_driver = {
 337         .verify         = cbe_cpufreq_verify,
 338         .target         = cbe_cpufreq_target,
 339         .init           = cbe_cpufreq_cpu_init,
 340         .exit           = cbe_cpufreq_cpu_exit,
 341         .name           = "cbe-cpufreq",
 342         .owner          = THIS_MODULE,
 343         .flags          = CPUFREQ_CONST_LOOPS,
 344 };
 345
 346 /*
 347  * module init and destoy
 348  */
 349
 350 static int __init cbe_cpufreq_init(void)
 351 {
 352         if (!machine_is(cell))
 353                 return -ENODEV;
 354
 355         cbe_cpufreq_has_pmi = pmi_register_handler(&cbe_pmi_handler) == 0;
 356
 357         if (cbe_cpufreq_has_pmi)
 358                 cpufreq_register_notifier(&pmi_notifier_block, CPUFREQ_POLICY_NOTIFIER);
 359
 360         return cpufreq_register_driver(&cbe_cpufreq_driver);
 361 }
 362
 363 static void __exit cbe_cpufreq_exit(void)
 364 {
 365         cpufreq_unregister_driver(&cbe_cpufreq_driver);
 366
 367         if (cbe_cpufreq_has_pmi) {
 368                 cpufreq_unregister_notifier(&pmi_notifier_block, CPUFREQ_POLICY_NOTIFIER);
 369                 pmi_unregister_handler(&cbe_pmi_handler);
 370         }
 371 }
 372
 373 module_init(cbe_cpufreq_init);
 374 module_exit(cbe_cpufreq_exit);
 375
 376 MODULE_LICENSE("GPL");
 377 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");