arch/sparc/kernel/us3_cpufreq.c

   1 /* us3_cpufreq.c: UltraSPARC-III 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/init.h>
  17
  18 #include <asm/head.h>
  19 #include <asm/timer.h>
  20
  21 static struct cpufreq_driver *cpufreq_us3_driver;
  22
  23 struct us3_freq_percpu_info {
  24         struct cpufreq_frequency_table table[4];
  25 };
  26
  27 /* Indexed by cpu number. */
  28 static struct us3_freq_percpu_info *us3_freq_table;
  29
  30 /* UltraSPARC-III has three dividers: 1, 2, and 32.  These are controlled
  31  * in the Safari config register.
  32  */
  33 #define SAFARI_CFG_DIV_1        0x0000000000000000UL
  34 #define SAFARI_CFG_DIV_2        0x0000000040000000UL
  35 #define SAFARI_CFG_DIV_32       0x0000000080000000UL
  36 #define SAFARI_CFG_DIV_MASK     0x00000000C0000000UL
  37
  38 static unsigned long read_safari_cfg(void)
  39 {
  40         unsigned long ret;
  41
  42         __asm__ __volatile__("ldxa      [%%g0] %1, %0"
  43                              : "=&r" (ret)
  44                              : "i" (ASI_SAFARI_CONFIG));
  45         return ret;
  46 }
  47
  48 static void write_safari_cfg(unsigned long val)
  49 {
  50         __asm__ __volatile__("stxa      %0, [%%g0] %1\n\t"
  51                              "membar    #Sync"
  52                              : /* no outputs */
  53                              : "r" (val), "i" (ASI_SAFARI_CONFIG)
  54                              : "memory");
  55 }
  56
  57 static unsigned long get_current_freq(unsigned int cpu, unsigned long safari_cfg)
  58 {
  59         unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
  60         unsigned long ret;
  61
  62         switch (safari_cfg & SAFARI_CFG_DIV_MASK) {
  63         case SAFARI_CFG_DIV_1:
  64                 ret = clock_tick / 1;
  65                 break;
  66         case SAFARI_CFG_DIV_2:
  67                 ret = clock_tick / 2;
  68                 break;
  69         case SAFARI_CFG_DIV_32:
  70                 ret = clock_tick / 32;
  71                 break;
  72         default:
  73                 BUG();
  74         };
  75
  76         return ret;
  77 }
  78
  79 static unsigned int us3_freq_get(unsigned int cpu)
  80 {
  81         cpumask_t cpus_allowed;
  82         unsigned long reg;
  83         unsigned int ret;
  84
  85         if (!cpu_online(cpu))
  86                 return 0;
  87
  88         cpus_allowed = current->cpus_allowed;
  89         set_cpus_allowed(current, cpumask_of_cpu(cpu));
  90
  91         reg = read_safari_cfg();
  92         ret = get_current_freq(cpu, reg);
  93
  94         set_cpus_allowed(current, cpus_allowed);
  95
  96         return ret;
  97 }
  98
  99 static void us3_set_cpu_divider_index(unsigned int cpu, unsigned int index)
 100 {
 101         unsigned long new_bits, new_freq, reg;
 102         cpumask_t cpus_allowed;
 103         struct cpufreq_freqs freqs;
 104
 105         if (!cpu_online(cpu))
 106                 return;
 107
 108         cpus_allowed = current->cpus_allowed;
 109         set_cpus_allowed(current, cpumask_of_cpu(cpu));
 110
 111         new_freq = sparc64_get_clock_tick(cpu) / 1000;
 112         switch (index) {
 113         case 0:
 114                 new_bits = SAFARI_CFG_DIV_1;
 115                 new_freq /= 1;
 116                 break;
 117         case 1:
 118                 new_bits = SAFARI_CFG_DIV_2;
 119                 new_freq /= 2;
 120                 break;
 121         case 2:
 122                 new_bits = SAFARI_CFG_DIV_32;
 123                 new_freq /= 32;
 124                 break;
 125
 126         default:
 127                 BUG();
 128         };
 129
 130         reg = read_safari_cfg();
 131
 132         freqs.old = get_current_freq(cpu, reg);
 133         freqs.new = new_freq;
 134         freqs.cpu = cpu;
 135         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 136
 137         reg &= ~SAFARI_CFG_DIV_MASK;
 138         reg |= new_bits;
 139         write_safari_cfg(reg);
 140
 141         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 142
 143         set_cpus_allowed(current, cpus_allowed);
 144 }
 145
 146 static int us3_freq_target(struct cpufreq_policy *policy,
 147                           unsigned int target_freq,
 148                           unsigned int relation)
 149 {
 150         unsigned int new_index = 0;
 151
 152         if (cpufreq_frequency_table_target(policy,
 153                                            &us3_freq_table[policy->cpu].table[0],
 154                                            target_freq,
 155                                            relation,
 156                                            &new_index))
 157                 return -EINVAL;
 158
 159         us3_set_cpu_divider_index(policy->cpu, new_index);
 160
 161         return 0;
 162 }
 163
 164 static int us3_freq_verify(struct cpufreq_policy *policy)
 165 {
 166         return cpufreq_frequency_table_verify(policy,
 167                                               &us3_freq_table[policy->cpu].table[0]);
 168 }
 169
 170 static int __init us3_freq_cpu_init(struct cpufreq_policy *policy)
 171 {
 172         unsigned int cpu = policy->cpu;
 173         unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 174         struct cpufreq_frequency_table *table =
 175                 &us3_freq_table[cpu].table[0];
 176
 177         table[0].index = 0;
 178         table[0].frequency = clock_tick / 1;
 179         table[1].index = 1;
 180         table[1].frequency = clock_tick / 2;
 181         table[2].index = 2;
 182         table[2].frequency = clock_tick / 32;
 183         table[3].index = 0;
 184         table[3].frequency = CPUFREQ_TABLE_END;
 185
 186         policy->cpuinfo.transition_latency = 0;
 187         policy->cur = clock_tick;
 188
 189         return cpufreq_frequency_table_cpuinfo(policy, table);
 190 }
 191
 192 static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
 193 {
 194         if (cpufreq_us3_driver)
 195                 us3_set_cpu_divider_index(policy->cpu, 0);
 196
 197         return 0;
 198 }
 199
 200 static int __init us3_freq_init(void)
 201 {
 202         unsigned long manuf, impl, ver;
 203         int ret;
 204
 205         if (tlb_type != cheetah && tlb_type != cheetah_plus)
 206                 return -ENODEV;
 207
 208         __asm__("rdpr %%ver, %0" : "=r" (ver));
 209         manuf = ((ver >> 48) & 0xffff);
 210         impl  = ((ver >> 32) & 0xffff);
 211
 212         if (manuf == CHEETAH_MANUF &&
 213             (impl == CHEETAH_IMPL ||
 214              impl == CHEETAH_PLUS_IMPL ||
 215              impl == JAGUAR_IMPL ||
 216              impl == PANTHER_IMPL)) {
 217                 struct cpufreq_driver *driver;
 218
 219                 ret = -ENOMEM;
 220                 driver = kzalloc(sizeof(struct cpufreq_driver), GFP_KERNEL);
 221                 if (!driver)
 222                         goto err_out;
 223
 224                 us3_freq_table = kzalloc(
 225                         (NR_CPUS * sizeof(struct us3_freq_percpu_info)),
 226                         GFP_KERNEL);
 227                 if (!us3_freq_table)
 228                         goto err_out;
 229
 230                 driver->init = us3_freq_cpu_init;
 231                 driver->verify = us3_freq_verify;
 232                 driver->target = us3_freq_target;
 233                 driver->get = us3_freq_get;
 234                 driver->exit = us3_freq_cpu_exit;
 235                 driver->owner = THIS_MODULE,
 236                 strcpy(driver->name, "UltraSPARC-III");
 237
 238                 cpufreq_us3_driver = driver;
 239                 ret = cpufreq_register_driver(driver);
 240                 if (ret)
 241                         goto err_out;
 242
 243                 return 0;
 244
 245 err_out:
 246                 if (driver) {
 247                         kfree(driver);
 248                         cpufreq_us3_driver = NULL;
 249                 }
 250                 kfree(us3_freq_table);
 251                 us3_freq_table = NULL;
 252                 return ret;
 253         }
 254
 255         return -ENODEV;
 256 }
 257
 258 static void __exit us3_freq_exit(void)
 259 {
 260         if (cpufreq_us3_driver) {
 261                 cpufreq_unregister_driver(cpufreq_us3_driver);
 262                 kfree(cpufreq_us3_driver);
 263                 cpufreq_us3_driver = NULL;
 264                 kfree(us3_freq_table);
 265                 us3_freq_table = NULL;
 266         }
 267 }
 268
 269 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
 270 MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
 271 MODULE_LICENSE("GPL");
 272
 273 module_init(us3_freq_init);
 274 module_exit(us3_freq_exit);