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   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);
  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 void us3_set_cpu_divider_index(unsigned int cpu, unsigned int index)
  80 {
  81         unsigned long new_bits, new_freq, reg;
  82         cpumask_t cpus_allowed;
  83         struct cpufreq_freqs freqs;
  84
  85         if (!cpu_online(cpu))
  86                 return;
  87
  88         cpus_allowed = current->cpus_allowed;
  89         set_cpus_allowed(current, cpumask_of_cpu(cpu));
  90
  91         new_freq = sparc64_get_clock_tick(cpu);
  92         switch (index) {
  93         case 0:
  94                 new_bits = SAFARI_CFG_DIV_1;
  95                 new_freq /= 1;
  96                 break;
  97         case 1:
  98                 new_bits = SAFARI_CFG_DIV_2;
  99                 new_freq /= 2;
 100                 break;
 101         case 2:
 102                 new_bits = SAFARI_CFG_DIV_32;
 103                 new_freq /= 32;
 104                 break;
 105
 106         default:
 107                 BUG();
 108         };
 109
 110         reg = read_safari_cfg();
 111
 112         freqs.old = get_current_freq(cpu, reg);
 113         freqs.new = new_freq;
 114         freqs.cpu = cpu;
 115         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 116
 117         reg &= ~SAFARI_CFG_DIV_MASK;
 118         reg |= new_bits;
 119         write_safari_cfg(reg);
 120
 121         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 122
 123         set_cpus_allowed(current, cpus_allowed);
 124 }
 125
 126 static int us3_freq_target(struct cpufreq_policy *policy,
 127                           unsigned int target_freq,
 128                           unsigned int relation)
 129 {
 130         unsigned int new_index = 0;
 131
 132         if (cpufreq_frequency_table_target(policy,
 133                                            &us3_freq_table[policy->cpu].table[0],
 134                                            target_freq,
 135                                            relation,
 136                                            &new_index))
 137                 return -EINVAL;
 138
 139         us3_set_cpu_divider_index(policy->cpu, new_index);
 140
 141         return 0;
 142 }
 143
 144 static int us3_freq_verify(struct cpufreq_policy *policy)
 145 {
 146         return cpufreq_frequency_table_verify(policy,
 147                                               &us3_freq_table[policy->cpu].table[0]);
 148 }
 149
 150 static int __init us3_freq_cpu_init(struct cpufreq_policy *policy)
 151 {
 152         unsigned int cpu = policy->cpu;
 153         unsigned long clock_tick = sparc64_get_clock_tick(cpu);
 154         struct cpufreq_frequency_table *table =
 155                 &us3_freq_table[cpu].table[0];
 156
 157         table[0].index = 0;
 158         table[0].frequency = clock_tick / 1;
 159         table[1].index = 1;
 160         table[1].frequency = clock_tick / 2;
 161         table[2].index = 2;
 162         table[2].frequency = clock_tick / 32;
 163         table[3].index = 0;
 164         table[3].frequency = CPUFREQ_TABLE_END;
 165
 166         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 167         policy->cpuinfo.transition_latency = 0;
 168         policy->cur = clock_tick;
 169
 170         return cpufreq_frequency_table_cpuinfo(policy, table);
 171 }
 172
 173 static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
 174 {
 175         if (cpufreq_us3_driver)
 176                 us3_set_cpu_divider_index(policy->cpu, 0);
 177
 178         return 0;
 179 }
 180
 181 static int __init us3_freq_init(void)
 182 {
 183         unsigned long manuf, impl, ver;
 184         int ret;
 185
 186         __asm__("rdpr %%ver, %0" : "=r" (ver));
 187         manuf = ((ver >> 48) & 0xffff);
 188         impl  = ((ver >> 32) & 0xffff);
 189
 190         if (manuf == CHEETAH_MANUF &&
 191             (impl == CHEETAH_IMPL || impl == CHEETAH_PLUS_IMPL)) {
 192                 struct cpufreq_driver *driver;
 193
 194                 ret = -ENOMEM;
 195                 driver = kmalloc(sizeof(struct cpufreq_driver), GFP_KERNEL);
 196                 if (!driver)
 197                         goto err_out;
 198                 memset(driver, 0, sizeof(*driver));
 199
 200                 us3_freq_table = kmalloc(
 201                         (NR_CPUS * sizeof(struct us3_freq_percpu_info)),
 202                         GFP_KERNEL);
 203                 if (!us3_freq_table)
 204                         goto err_out;
 205
 206                 memset(us3_freq_table, 0,
 207                        (NR_CPUS * sizeof(struct us3_freq_percpu_info)));
 208
 209                 driver->verify = us3_freq_verify;
 210                 driver->target = us3_freq_target;
 211                 driver->init = us3_freq_cpu_init;
 212                 driver->exit = us3_freq_cpu_exit;
 213                 driver->owner = THIS_MODULE,
 214                 strcpy(driver->name, "UltraSPARC-III");
 215
 216                 cpufreq_us3_driver = driver;
 217                 ret = cpufreq_register_driver(driver);
 218                 if (ret)
 219                         goto err_out;
 220
 221                 return 0;
 222
 223 err_out:
 224                 if (driver) {
 225                         kfree(driver);
 226                         cpufreq_us3_driver = NULL;
 227                 }
 228                 if (us3_freq_table) {
 229                         kfree(us3_freq_table);
 230                         us3_freq_table = NULL;
 231                 }
 232                 return ret;
 233         }
 234
 235         return -ENODEV;
 236 }
 237
 238 static void __exit us3_freq_exit(void)
 239 {
 240         if (cpufreq_us3_driver) {
 241                 cpufreq_unregister_driver(cpufreq_us3_driver);
 242
 243                 kfree(cpufreq_us3_driver);
 244                 cpufreq_us3_driver = NULL;
 245                 kfree(us3_freq_table);
 246                 us3_freq_table = NULL;
 247         }
 248 }
 249
 250 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
 251 MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
 252 MODULE_LICENSE("GPL");
 253
 254 module_init(us3_freq_init);
 255 module_exit(us3_freq_exit);