arch/sparc/kernel/us2e_cpufreq.c

   1 /* us2e_cpufreq.c: UltraSPARC-IIe cpu frequency support
   2  *
   3  * Copyright (C) 2003 David S. Miller (davem@redhat.com)
   4  *
   5  * Many thanks to Dominik Brodowski for fixing up the cpufreq
   6  * infrastructure in order to make this driver easier to implement.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/sched.h>
  12 #include <linux/smp.h>
  13 #include <linux/cpufreq.h>
  14 #include <linux/threads.h>
  15 #include <linux/slab.h>
  16 #include <linux/delay.h>
  17 #include <linux/init.h>
  18
  19 #include <asm/asi.h>
  20 #include <asm/timer.h>
  21
  22 static struct cpufreq_driver *cpufreq_us2e_driver;
  23
  24 struct us2e_freq_percpu_info {
  25         struct cpufreq_frequency_table table[6];
  26 };
  27
  28 /* Indexed by cpu number. */
  29 static struct us2e_freq_percpu_info *us2e_freq_table;
  30
  31 #define HBIRD_MEM_CNTL0_ADDR    0x1fe0000f010UL
  32 #define HBIRD_ESTAR_MODE_ADDR   0x1fe0000f080UL
  33
  34 /* UltraSPARC-IIe has five dividers: 1, 2, 4, 6, and 8.  These are controlled
  35  * in the ESTAR mode control register.
  36  */
  37 #define ESTAR_MODE_DIV_1        0x0000000000000000UL
  38 #define ESTAR_MODE_DIV_2        0x0000000000000001UL
  39 #define ESTAR_MODE_DIV_4        0x0000000000000003UL
  40 #define ESTAR_MODE_DIV_6        0x0000000000000002UL
  41 #define ESTAR_MODE_DIV_8        0x0000000000000004UL
  42 #define ESTAR_MODE_DIV_MASK     0x0000000000000007UL
  43
  44 #define MCTRL0_SREFRESH_ENAB    0x0000000000010000UL
  45 #define MCTRL0_REFR_COUNT_MASK  0x0000000000007f00UL
  46 #define MCTRL0_REFR_COUNT_SHIFT 8
  47 #define MCTRL0_REFR_INTERVAL    7800
  48 #define MCTRL0_REFR_CLKS_P_CNT  64
  49
  50 static unsigned long read_hbreg(unsigned long addr)
  51 {
  52         unsigned long ret;
  53
  54         __asm__ __volatile__("ldxa      [%1] %2, %0"
  55                              : "=&r" (ret)
  56                              : "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E));
  57         return ret;
  58 }
  59
  60 static void write_hbreg(unsigned long addr, unsigned long val)
  61 {
  62         __asm__ __volatile__("stxa      %0, [%1] %2\n\t"
  63                              "membar    #Sync"
  64                              : /* no outputs */
  65                              : "r" (val), "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E)
  66                              : "memory");
  67         if (addr == HBIRD_ESTAR_MODE_ADDR) {
  68                 /* Need to wait 16 clock cycles for the PLL to lock.  */
  69                 udelay(1);
  70         }
  71 }
  72
  73 static void self_refresh_ctl(int enable)
  74 {
  75         unsigned long mctrl = read_hbreg(HBIRD_MEM_CNTL0_ADDR);
  76
  77         if (enable)
  78                 mctrl |= MCTRL0_SREFRESH_ENAB;
  79         else
  80                 mctrl &= ~MCTRL0_SREFRESH_ENAB;
  81         write_hbreg(HBIRD_MEM_CNTL0_ADDR, mctrl);
  82         (void) read_hbreg(HBIRD_MEM_CNTL0_ADDR);
  83 }
  84
  85 static void frob_mem_refresh(int cpu_slowing_down,
  86                              unsigned long clock_tick,
  87                              unsigned long old_divisor, unsigned long divisor)
  88 {
  89         unsigned long old_refr_count, refr_count, mctrl;
  90
  91         refr_count  = (clock_tick * MCTRL0_REFR_INTERVAL);
  92         refr_count /= (MCTRL0_REFR_CLKS_P_CNT * divisor * 1000000000UL);
  93
  94         mctrl = read_hbreg(HBIRD_MEM_CNTL0_ADDR);
  95         old_refr_count = (mctrl & MCTRL0_REFR_COUNT_MASK)
  96                 >> MCTRL0_REFR_COUNT_SHIFT;
  97
  98         mctrl &= ~MCTRL0_REFR_COUNT_MASK;
  99         mctrl |= refr_count << MCTRL0_REFR_COUNT_SHIFT;
 100         write_hbreg(HBIRD_MEM_CNTL0_ADDR, mctrl);
 101         mctrl = read_hbreg(HBIRD_MEM_CNTL0_ADDR);
 102
 103         if (cpu_slowing_down && !(mctrl & MCTRL0_SREFRESH_ENAB)) {
 104                 unsigned long usecs;
 105
 106                 /* We have to wait for both refresh counts (old
 107                  * and new) to go to zero.
 108                  */
 109                 usecs = (MCTRL0_REFR_CLKS_P_CNT *
 110                          (refr_count + old_refr_count) *
 111                          1000000UL *
 112                          old_divisor) / clock_tick;
 113                 udelay(usecs + 1UL);
 114         }
 115 }
 116
 117 static void us2e_transition(unsigned long estar, unsigned long new_bits,
 118                             unsigned long clock_tick,
 119                             unsigned long old_divisor, unsigned long divisor)
 120 {
 121         unsigned long flags;
 122
 123         local_irq_save(flags);
 124
 125         estar &= ~ESTAR_MODE_DIV_MASK;
 126
 127         /* This is based upon the state transition diagram in the IIe manual.  */
 128         if (old_divisor == 2 && divisor == 1) {
 129                 self_refresh_ctl(0);
 130                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 131                 frob_mem_refresh(0, clock_tick, old_divisor, divisor);
 132         } else if (old_divisor == 1 && divisor == 2) {
 133                 frob_mem_refresh(1, clock_tick, old_divisor, divisor);
 134                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 135                 self_refresh_ctl(1);
 136         } else if (old_divisor == 1 && divisor > 2) {
 137                 us2e_transition(estar, ESTAR_MODE_DIV_2, clock_tick,
 138                                 1, 2);
 139                 us2e_transition(estar, new_bits, clock_tick,
 140                                 2, divisor);
 141         } else if (old_divisor > 2 && divisor == 1) {
 142                 us2e_transition(estar, ESTAR_MODE_DIV_2, clock_tick,
 143                                 old_divisor, 2);
 144                 us2e_transition(estar, new_bits, clock_tick,
 145                                 2, divisor);
 146         } else if (old_divisor < divisor) {
 147                 frob_mem_refresh(0, clock_tick, old_divisor, divisor);
 148                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 149         } else if (old_divisor > divisor) {
 150                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 151                 frob_mem_refresh(1, clock_tick, old_divisor, divisor);
 152         } else {
 153                 BUG();
 154         }
 155
 156         local_irq_restore(flags);
 157 }
 158
 159 static unsigned long index_to_estar_mode(unsigned int index)
 160 {
 161         switch (index) {
 162         case 0:
 163                 return ESTAR_MODE_DIV_1;
 164
 165         case 1:
 166                 return ESTAR_MODE_DIV_2;
 167
 168         case 2:
 169                 return ESTAR_MODE_DIV_4;
 170
 171         case 3:
 172                 return ESTAR_MODE_DIV_6;
 173
 174         case 4:
 175                 return ESTAR_MODE_DIV_8;
 176
 177         default:
 178                 BUG();
 179         };
 180 }
 181
 182 static unsigned long index_to_divisor(unsigned int index)
 183 {
 184         switch (index) {
 185         case 0:
 186                 return 1;
 187
 188         case 1:
 189                 return 2;
 190
 191         case 2:
 192                 return 4;
 193
 194         case 3:
 195                 return 6;
 196
 197         case 4:
 198                 return 8;
 199
 200         default:
 201                 BUG();
 202         };
 203 }
 204
 205 static unsigned long estar_to_divisor(unsigned long estar)
 206 {
 207         unsigned long ret;
 208
 209         switch (estar & ESTAR_MODE_DIV_MASK) {
 210         case ESTAR_MODE_DIV_1:
 211                 ret = 1;
 212                 break;
 213         case ESTAR_MODE_DIV_2:
 214                 ret = 2;
 215                 break;
 216         case ESTAR_MODE_DIV_4:
 217                 ret = 4;
 218                 break;
 219         case ESTAR_MODE_DIV_6:
 220                 ret = 6;
 221                 break;
 222         case ESTAR_MODE_DIV_8:
 223                 ret = 8;
 224                 break;
 225         default:
 226                 BUG();
 227         };
 228
 229         return ret;
 230 }
 231
 232 static unsigned int us2e_freq_get(unsigned int cpu)
 233 {
 234         cpumask_t cpus_allowed;
 235         unsigned long clock_tick, estar;
 236
 237         if (!cpu_online(cpu))
 238                 return 0;
 239
 240         cpus_allowed = current->cpus_allowed;
 241         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 242
 243         clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 244         estar = read_hbreg(HBIRD_ESTAR_MODE_ADDR);
 245
 246         set_cpus_allowed_ptr(current, &cpus_allowed);
 247
 248         return clock_tick / estar_to_divisor(estar);
 249 }
 250
 251 static void us2e_set_cpu_divider_index(unsigned int cpu, unsigned int index)
 252 {
 253         unsigned long new_bits, new_freq;
 254         unsigned long clock_tick, divisor, old_divisor, estar;
 255         cpumask_t cpus_allowed;
 256         struct cpufreq_freqs freqs;
 257
 258         if (!cpu_online(cpu))
 259                 return;
 260
 261         cpus_allowed = current->cpus_allowed;
 262         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 263
 264         new_freq = clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 265         new_bits = index_to_estar_mode(index);
 266         divisor = index_to_divisor(index);
 267         new_freq /= divisor;
 268
 269         estar = read_hbreg(HBIRD_ESTAR_MODE_ADDR);
 270
 271         old_divisor = estar_to_divisor(estar);
 272
 273         freqs.old = clock_tick / old_divisor;
 274         freqs.new = new_freq;
 275         freqs.cpu = cpu;
 276         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 277
 278         if (old_divisor != divisor)
 279                 us2e_transition(estar, new_bits, clock_tick * 1000,
 280                                 old_divisor, divisor);
 281
 282         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 283
 284         set_cpus_allowed_ptr(current, &cpus_allowed);
 285 }
 286
 287 static int us2e_freq_target(struct cpufreq_policy *policy,
 288                           unsigned int target_freq,
 289                           unsigned int relation)
 290 {
 291         unsigned int new_index = 0;
 292
 293         if (cpufreq_frequency_table_target(policy,
 294                                            &us2e_freq_table[policy->cpu].table[0],
 295                                            target_freq, relation, &new_index))
 296                 return -EINVAL;
 297
 298         us2e_set_cpu_divider_index(policy->cpu, new_index);
 299
 300         return 0;
 301 }
 302
 303 static int us2e_freq_verify(struct cpufreq_policy *policy)
 304 {
 305         return cpufreq_frequency_table_verify(policy,
 306                                               &us2e_freq_table[policy->cpu].table[0]);
 307 }
 308
 309 static int __init us2e_freq_cpu_init(struct cpufreq_policy *policy)
 310 {
 311         unsigned int cpu = policy->cpu;
 312         unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 313         struct cpufreq_frequency_table *table =
 314                 &us2e_freq_table[cpu].table[0];
 315
 316         table[0].index = 0;
 317         table[0].frequency = clock_tick / 1;
 318         table[1].index = 1;
 319         table[1].frequency = clock_tick / 2;
 320         table[2].index = 2;
 321         table[2].frequency = clock_tick / 4;
 322         table[2].index = 3;
 323         table[2].frequency = clock_tick / 6;
 324         table[2].index = 4;
 325         table[2].frequency = clock_tick / 8;
 326         table[2].index = 5;
 327         table[3].frequency = CPUFREQ_TABLE_END;
 328
 329         policy->cpuinfo.transition_latency = 0;
 330         policy->cur = clock_tick;
 331
 332         return cpufreq_frequency_table_cpuinfo(policy, table);
 333 }
 334
 335 static int us2e_freq_cpu_exit(struct cpufreq_policy *policy)
 336 {
 337         if (cpufreq_us2e_driver)
 338                 us2e_set_cpu_divider_index(policy->cpu, 0);
 339
 340         return 0;
 341 }
 342
 343 static int __init us2e_freq_init(void)
 344 {
 345         unsigned long manuf, impl, ver;
 346         int ret;
 347
 348         if (tlb_type != spitfire)
 349                 return -ENODEV;
 350
 351         __asm__("rdpr %%ver, %0" : "=r" (ver));
 352         manuf = ((ver >> 48) & 0xffff);
 353         impl  = ((ver >> 32) & 0xffff);
 354
 355         if (manuf == 0x17 && impl == 0x13) {
 356                 struct cpufreq_driver *driver;
 357
 358                 ret = -ENOMEM;
 359                 driver = kzalloc(sizeof(struct cpufreq_driver), GFP_KERNEL);
 360                 if (!driver)
 361                         goto err_out;
 362
 363                 us2e_freq_table = kzalloc(
 364                         (NR_CPUS * sizeof(struct us2e_freq_percpu_info)),
 365                         GFP_KERNEL);
 366                 if (!us2e_freq_table)
 367                         goto err_out;
 368
 369                 driver->init = us2e_freq_cpu_init;
 370                 driver->verify = us2e_freq_verify;
 371                 driver->target = us2e_freq_target;
 372                 driver->get = us2e_freq_get;
 373                 driver->exit = us2e_freq_cpu_exit;
 374                 driver->owner = THIS_MODULE,
 375                 strcpy(driver->name, "UltraSPARC-IIe");
 376
 377                 cpufreq_us2e_driver = driver;
 378                 ret = cpufreq_register_driver(driver);
 379                 if (ret)
 380                         goto err_out;
 381
 382                 return 0;
 383
 384 err_out:
 385                 if (driver) {
 386                         kfree(driver);
 387                         cpufreq_us2e_driver = NULL;
 388                 }
 389                 kfree(us2e_freq_table);
 390                 us2e_freq_table = NULL;
 391                 return ret;
 392         }
 393
 394         return -ENODEV;
 395 }
 396
 397 static void __exit us2e_freq_exit(void)
 398 {
 399         if (cpufreq_us2e_driver) {
 400                 cpufreq_unregister_driver(cpufreq_us2e_driver);
 401                 kfree(cpufreq_us2e_driver);
 402                 cpufreq_us2e_driver = NULL;
 403                 kfree(us2e_freq_table);
 404                 us2e_freq_table = NULL;
 405         }
 406 }
 407
 408 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
 409 MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-IIe");
 410 MODULE_LICENSE("GPL");
 411
 412 module_init(us2e_freq_init);
 413 module_exit(us2e_freq_exit);