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 unsigned int pmi_frequency_limit = 0;
  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         u64 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 = (u64) get_cycles();
  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 = (u64) get_cycles() - time; /* actual cycles (not cpu cycles!) */
 102         time = 1000000000 * time / CLOCK_TICK_RATE; /* time in ns (10^-9) */
 103         pr_debug("had to wait %lu ns for a transition\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
 127         local_irq_save(flags);
 128
 129         mic_tm_regs = cbe_get_cpu_mic_tm_regs(cpu);
 130         pmd_regs = cbe_get_cpu_pmd_regs(cpu);
 131
 132         pr_debug("pm register is mapped at %p\n", &pmd_regs->pmcr);
 133         pr_debug("mic register is mapped at %p\n", &mic_tm_regs->slow_fast_timer_0);
 134
 135         out_be64(&mic_tm_regs->slow_fast_timer_0, MIC_Slow_Fast_Timer_table[pmode]);
 136         out_be64(&mic_tm_regs->slow_fast_timer_1, MIC_Slow_Fast_Timer_table[pmode]);
 137
 138         out_be64(&mic_tm_regs->slow_next_timer_0, MIC_Slow_Next_Timer_table[pmode]);
 139         out_be64(&mic_tm_regs->slow_next_timer_1, MIC_Slow_Next_Timer_table[pmode]);
 140
 141         value = in_be64(&pmd_regs->pmcr);
 142         /* set bits to zero */
 143         value &= 0xFFFFFFFFFFFFFFF8ull;
 144         /* set bits to next pmode */
 145         value |= pmode;
 146
 147         out_be64(&pmd_regs->pmcr, value);
 148
 149         /* wait until new pmode appears in status register */
 150         value = in_be64(&pmd_regs->pmsr) & 0x07;
 151         while(value != pmode) {
 152                 cpu_relax();
 153                 value = in_be64(&pmd_regs->pmsr) & 0x07;
 154         }
 155
 156         local_irq_restore(flags);
 157
 158         return 0;
 159 }
 160
 161 static int set_pmode(int cpu, unsigned int slow_mode)
 162 {
 163 #ifdef CONFIG_PPC_PMI
 164         if (cbe_cpufreq_has_pmi)
 165                 return set_pmode_pmi(cpu, slow_mode);
 166 #endif
 167         return set_pmode_reg(cpu, slow_mode);
 168 }
 169
 170 static void cbe_cpufreq_handle_pmi(pmi_message_t pmi_msg)
 171 {
 172         u8 cpu;
 173         u8 cbe_pmode_new;
 174
 175         BUG_ON(pmi_msg.type != PMI_TYPE_FREQ_CHANGE);
 176
 177         cpu = cbe_node_to_cpu(pmi_msg.data1);
 178         cbe_pmode_new = pmi_msg.data2;
 179
 180         pmi_frequency_limit = cbe_freqs[cbe_pmode_new].frequency;
 181
 182         pr_debug("cbe_handle_pmi: max freq=%d\n", pmi_frequency_limit);
 183 }
 184
 185 static int pmi_notifier(struct notifier_block *nb,
 186                                        unsigned long event, void *data)
 187 {
 188         struct cpufreq_policy *policy = data;
 189
 190         if (event != CPUFREQ_INCOMPATIBLE)
 191                 return 0;
 192
 193         cpufreq_verify_within_limits(policy, 0, pmi_frequency_limit);
 194         return 0;
 195 }
 196
 197 static struct notifier_block pmi_notifier_block = {
 198         .notifier_call = pmi_notifier,
 199 };
 200
 201 static struct pmi_handler cbe_pmi_handler = {
 202         .type                   = PMI_TYPE_FREQ_CHANGE,
 203         .handle_pmi_message     = cbe_cpufreq_handle_pmi,
 204 };
 205
 206
 207 /*
 208  * cpufreq functions
 209  */
 210
 211 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
 212 {
 213         const u32 *max_freqp;
 214         u32 max_freq;
 215         int i, cur_pmode;
 216         struct device_node *cpu;
 217
 218         cpu = of_get_cpu_node(policy->cpu, NULL);
 219
 220         if (!cpu)
 221                 return -ENODEV;
 222
 223         pr_debug("init cpufreq on CPU %d\n", policy->cpu);
 224
 225         max_freqp = of_get_property(cpu, "clock-frequency", NULL);
 226
 227         if (!max_freqp)
 228                 return -EINVAL;
 229
 230         /* we need the freq in kHz */
 231         max_freq = *max_freqp / 1000;
 232
 233         pr_debug("max clock-frequency is at %u kHz\n", max_freq);
 234         pr_debug("initializing frequency table\n");
 235
 236         /* initialize frequency table */
 237         for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
 238                 cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index;
 239                 pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
 240         }
 241
 242         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 243         /* if DEBUG is enabled set_pmode() measures the correct latency of a transition */
 244         policy->cpuinfo.transition_latency = 25000;
 245
 246         cur_pmode = get_pmode(policy->cpu);
 247         pr_debug("current pmode is at %d\n",cur_pmode);
 248
 249         policy->cur = cbe_freqs[cur_pmode].frequency;
 250
 251 #ifdef CONFIG_SMP
 252         policy->cpus = cpu_sibling_map[policy->cpu];
 253 #endif
 254
 255         cpufreq_frequency_table_get_attr(cbe_freqs, policy->cpu);
 256
 257         if (cbe_cpufreq_has_pmi) {
 258                 /* frequency might get limited later, initialize limit with max_freq */
 259                 pmi_frequency_limit = max_freq;
 260                 cpufreq_register_notifier(&pmi_notifier_block, CPUFREQ_POLICY_NOTIFIER);
 261         }
 262
 263         /* this ensures that policy->cpuinfo_min and policy->cpuinfo_max are set correctly */
 264         return cpufreq_frequency_table_cpuinfo(policy, cbe_freqs);
 265 }
 266
 267 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 268 {
 269         if (cbe_cpufreq_has_pmi)
 270                 cpufreq_unregister_notifier(&pmi_notifier_block, CPUFREQ_POLICY_NOTIFIER);
 271
 272         cpufreq_frequency_table_put_attr(policy->cpu);
 273         return 0;
 274 }
 275
 276 static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
 277 {
 278         return cpufreq_frequency_table_verify(policy, cbe_freqs);
 279 }
 280
 281
 282 static int cbe_cpufreq_target(struct cpufreq_policy *policy, unsigned int target_freq,
 283                             unsigned int relation)
 284 {
 285         int rc;
 286         struct cpufreq_freqs freqs;
 287         int cbe_pmode_new;
 288
 289         cpufreq_frequency_table_target(policy,
 290                                        cbe_freqs,
 291                                        target_freq,
 292                                        relation,
 293                                        &cbe_pmode_new);
 294
 295         freqs.old = policy->cur;
 296         freqs.new = cbe_freqs[cbe_pmode_new].frequency;
 297         freqs.cpu = policy->cpu;
 298
 299         mutex_lock(&cbe_switch_mutex);
 300         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 301
 302         pr_debug("setting frequency for cpu %d to %d kHz, 1/%d of max frequency\n",
 303                  policy->cpu,
 304                  cbe_freqs[cbe_pmode_new].frequency,
 305                  cbe_freqs[cbe_pmode_new].index);
 306
 307         rc = set_pmode(policy->cpu, cbe_pmode_new);
 308         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 309         mutex_unlock(&cbe_switch_mutex);
 310
 311         return rc;
 312 }
 313
 314 static struct cpufreq_driver cbe_cpufreq_driver = {
 315         .verify         = cbe_cpufreq_verify,
 316         .target         = cbe_cpufreq_target,
 317         .init           = cbe_cpufreq_cpu_init,
 318         .exit           = cbe_cpufreq_cpu_exit,
 319         .name           = "cbe-cpufreq",
 320         .owner          = THIS_MODULE,
 321         .flags          = CPUFREQ_CONST_LOOPS,
 322 };
 323
 324 /*
 325  * module init and destoy
 326  */
 327
 328 static int __init cbe_cpufreq_init(void)
 329 {
 330         if (!machine_is(cell))
 331                 return -ENODEV;
 332
 333         cbe_cpufreq_has_pmi = pmi_register_handler(&cbe_pmi_handler) == 0;
 334
 335         return cpufreq_register_driver(&cbe_cpufreq_driver);
 336 }
 337
 338 static void __exit cbe_cpufreq_exit(void)
 339 {
 340         cpufreq_unregister_driver(&cbe_cpufreq_driver);
 341
 342         if (cbe_cpufreq_has_pmi)
 343                 pmi_unregister_handler(&cbe_pmi_handler);
 344 }
 345
 346 module_init(cbe_cpufreq_init);
 347 module_exit(cbe_cpufreq_exit);
 348
 349 MODULE_LICENSE("GPL");
 350 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");