drivers/cpufreq/sparc-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         estar &= ~ESTAR_MODE_DIV_MASK;
 122
 123         /* This is based upon the state transition diagram in the IIe manual.  */
 124         if (old_divisor == 2 && divisor == 1) {
 125                 self_refresh_ctl(0);
 126                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 127                 frob_mem_refresh(0, clock_tick, old_divisor, divisor);
 128         } else if (old_divisor == 1 && divisor == 2) {
 129                 frob_mem_refresh(1, clock_tick, old_divisor, divisor);
 130                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 131                 self_refresh_ctl(1);
 132         } else if (old_divisor == 1 && divisor > 2) {
 133                 us2e_transition(estar, ESTAR_MODE_DIV_2, clock_tick,
 134                                 1, 2);
 135                 us2e_transition(estar, new_bits, clock_tick,
 136                                 2, divisor);
 137         } else if (old_divisor > 2 && divisor == 1) {
 138                 us2e_transition(estar, ESTAR_MODE_DIV_2, clock_tick,
 139                                 old_divisor, 2);
 140                 us2e_transition(estar, new_bits, clock_tick,
 141                                 2, divisor);
 142         } else if (old_divisor < divisor) {
 143                 frob_mem_refresh(0, clock_tick, old_divisor, divisor);
 144                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 145         } else if (old_divisor > divisor) {
 146                 write_hbreg(HBIRD_ESTAR_MODE_ADDR, estar | new_bits);
 147                 frob_mem_refresh(1, clock_tick, old_divisor, divisor);
 148         } else {
 149                 BUG();
 150         }
 151 }
 152
 153 static unsigned long index_to_estar_mode(unsigned int index)
 154 {
 155         switch (index) {
 156         case 0:
 157                 return ESTAR_MODE_DIV_1;
 158
 159         case 1:
 160                 return ESTAR_MODE_DIV_2;
 161
 162         case 2:
 163                 return ESTAR_MODE_DIV_4;
 164
 165         case 3:
 166                 return ESTAR_MODE_DIV_6;
 167
 168         case 4:
 169                 return ESTAR_MODE_DIV_8;
 170
 171         default:
 172                 BUG();
 173         }
 174 }
 175
 176 static unsigned long index_to_divisor(unsigned int index)
 177 {
 178         switch (index) {
 179         case 0:
 180                 return 1;
 181
 182         case 1:
 183                 return 2;
 184
 185         case 2:
 186                 return 4;
 187
 188         case 3:
 189                 return 6;
 190
 191         case 4:
 192                 return 8;
 193
 194         default:
 195                 BUG();
 196         }
 197 }
 198
 199 static unsigned long estar_to_divisor(unsigned long estar)
 200 {
 201         unsigned long ret;
 202
 203         switch (estar & ESTAR_MODE_DIV_MASK) {
 204         case ESTAR_MODE_DIV_1:
 205                 ret = 1;
 206                 break;
 207         case ESTAR_MODE_DIV_2:
 208                 ret = 2;
 209                 break;
 210         case ESTAR_MODE_DIV_4:
 211                 ret = 4;
 212                 break;
 213         case ESTAR_MODE_DIV_6:
 214                 ret = 6;
 215                 break;
 216         case ESTAR_MODE_DIV_8:
 217                 ret = 8;
 218                 break;
 219         default:
 220                 BUG();
 221         }
 222
 223         return ret;
 224 }
 225
 226 static void __us2e_freq_get(void *arg)
 227 {
 228         unsigned long *estar = arg;
 229
 230         *estar = read_hbreg(HBIRD_ESTAR_MODE_ADDR);
 231 }
 232
 233 static unsigned int us2e_freq_get(unsigned int cpu)
 234 {
 235         unsigned long clock_tick, estar;
 236
 237         clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 238         if (smp_call_function_single(cpu, __us2e_freq_get, &estar, 1))
 239                 return 0;
 240
 241         return clock_tick / estar_to_divisor(estar);
 242 }
 243
 244 static void __us2e_freq_target(void *arg)
 245 {
 246         unsigned int cpu = smp_processor_id();
 247         unsigned int *index = arg;
 248         unsigned long new_bits, new_freq;
 249         unsigned long clock_tick, divisor, old_divisor, estar;
 250
 251         new_freq = clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 252         new_bits = index_to_estar_mode(*index);
 253         divisor = index_to_divisor(*index);
 254         new_freq /= divisor;
 255
 256         estar = read_hbreg(HBIRD_ESTAR_MODE_ADDR);
 257
 258         old_divisor = estar_to_divisor(estar);
 259
 260         if (old_divisor != divisor) {
 261                 us2e_transition(estar, new_bits, clock_tick * 1000,
 262                                 old_divisor, divisor);
 263         }
 264 }
 265
 266 static int us2e_freq_target(struct cpufreq_policy *policy, unsigned int index)
 267 {
 268         unsigned int cpu = policy->cpu;
 269
 270         return smp_call_function_single(cpu, __us2e_freq_target, &index, 1);
 271 }
 272
 273 static int __init us2e_freq_cpu_init(struct cpufreq_policy *policy)
 274 {
 275         unsigned int cpu = policy->cpu;
 276         unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 277         struct cpufreq_frequency_table *table =
 278                 &us2e_freq_table[cpu].table[0];
 279
 280         table[0].driver_data = 0;
 281         table[0].frequency = clock_tick / 1;
 282         table[1].driver_data = 1;
 283         table[1].frequency = clock_tick / 2;
 284         table[2].driver_data = 2;
 285         table[2].frequency = clock_tick / 4;
 286         table[2].driver_data = 3;
 287         table[2].frequency = clock_tick / 6;
 288         table[2].driver_data = 4;
 289         table[2].frequency = clock_tick / 8;
 290         table[2].driver_data = 5;
 291         table[3].frequency = CPUFREQ_TABLE_END;
 292
 293         policy->cpuinfo.transition_latency = 0;
 294         policy->cur = clock_tick;
 295
 296         return cpufreq_table_validate_and_show(policy, table);
 297 }
 298
 299 static int us2e_freq_cpu_exit(struct cpufreq_policy *policy)
 300 {
 301         if (cpufreq_us2e_driver)
 302                 us2e_freq_target(policy, 0);
 303
 304         return 0;
 305 }
 306
 307 static int __init us2e_freq_init(void)
 308 {
 309         unsigned long manuf, impl, ver;
 310         int ret;
 311
 312         if (tlb_type != spitfire)
 313                 return -ENODEV;
 314
 315         __asm__("rdpr %%ver, %0" : "=r" (ver));
 316         manuf = ((ver >> 48) & 0xffff);
 317         impl  = ((ver >> 32) & 0xffff);
 318
 319         if (manuf == 0x17 && impl == 0x13) {
 320                 struct cpufreq_driver *driver;
 321
 322                 ret = -ENOMEM;
 323                 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
 324                 if (!driver)
 325                         goto err_out;
 326
 327                 us2e_freq_table = kzalloc((NR_CPUS * sizeof(*us2e_freq_table)),
 328                         GFP_KERNEL);
 329                 if (!us2e_freq_table)
 330                         goto err_out;
 331
 332                 driver->init = us2e_freq_cpu_init;
 333                 driver->verify = cpufreq_generic_frequency_table_verify;
 334                 driver->target_index = us2e_freq_target;
 335                 driver->get = us2e_freq_get;
 336                 driver->exit = us2e_freq_cpu_exit;
 337                 strcpy(driver->name, "UltraSPARC-IIe");
 338
 339                 cpufreq_us2e_driver = driver;
 340                 ret = cpufreq_register_driver(driver);
 341                 if (ret)
 342                         goto err_out;
 343
 344                 return 0;
 345
 346 err_out:
 347                 if (driver) {
 348                         kfree(driver);
 349                         cpufreq_us2e_driver = NULL;
 350                 }
 351                 kfree(us2e_freq_table);
 352                 us2e_freq_table = NULL;
 353                 return ret;
 354         }
 355
 356         return -ENODEV;
 357 }
 358
 359 static void __exit us2e_freq_exit(void)
 360 {
 361         if (cpufreq_us2e_driver) {
 362                 cpufreq_unregister_driver(cpufreq_us2e_driver);
 363                 kfree(cpufreq_us2e_driver);
 364                 cpufreq_us2e_driver = NULL;
 365                 kfree(us2e_freq_table);
 366                 us2e_freq_table = NULL;
 367         }
 368 }
 369
 370 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
 371 MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-IIe");
 372 MODULE_LICENSE("GPL");
 373
 374 module_init(us2e_freq_init);
 375 module_exit(us2e_freq_exit);