drivers/cpufreq/sparc-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         cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
  86         set_cpus_allowed_ptr(current, cpumask_of(cpu));
  87
  88         reg = read_safari_cfg();
  89         ret = get_current_freq(cpu, reg);
  90
  91         set_cpus_allowed_ptr(current, &cpus_allowed);
  92
  93         return ret;
  94 }
  95
  96 static int us3_freq_target(struct cpufreq_policy *policy, unsigned int index)
  97 {
  98         unsigned int cpu = policy->cpu;
  99         unsigned long new_bits, new_freq, reg;
 100         cpumask_t cpus_allowed;
 101
 102         cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
 103         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 104
 105         new_freq = sparc64_get_clock_tick(cpu) / 1000;
 106         switch (index) {
 107         case 0:
 108                 new_bits = SAFARI_CFG_DIV_1;
 109                 new_freq /= 1;
 110                 break;
 111         case 1:
 112                 new_bits = SAFARI_CFG_DIV_2;
 113                 new_freq /= 2;
 114                 break;
 115         case 2:
 116                 new_bits = SAFARI_CFG_DIV_32;
 117                 new_freq /= 32;
 118                 break;
 119
 120         default:
 121                 BUG();
 122         }
 123
 124         reg = read_safari_cfg();
 125
 126         reg &= ~SAFARI_CFG_DIV_MASK;
 127         reg |= new_bits;
 128         write_safari_cfg(reg);
 129
 130         set_cpus_allowed_ptr(current, &cpus_allowed);
 131
 132         return 0;
 133 }
 134
 135 static int __init us3_freq_cpu_init(struct cpufreq_policy *policy)
 136 {
 137         unsigned int cpu = policy->cpu;
 138         unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 139         struct cpufreq_frequency_table *table =
 140                 &us3_freq_table[cpu].table[0];
 141
 142         table[0].driver_data = 0;
 143         table[0].frequency = clock_tick / 1;
 144         table[1].driver_data = 1;
 145         table[1].frequency = clock_tick / 2;
 146         table[2].driver_data = 2;
 147         table[2].frequency = clock_tick / 32;
 148         table[3].driver_data = 0;
 149         table[3].frequency = CPUFREQ_TABLE_END;
 150
 151         policy->cpuinfo.transition_latency = 0;
 152         policy->cur = clock_tick;
 153
 154         return cpufreq_table_validate_and_show(policy, table);
 155 }
 156
 157 static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
 158 {
 159         if (cpufreq_us3_driver)
 160                 us3_freq_target(policy, 0);
 161
 162         return 0;
 163 }
 164
 165 static int __init us3_freq_init(void)
 166 {
 167         unsigned long manuf, impl, ver;
 168         int ret;
 169
 170         if (tlb_type != cheetah && tlb_type != cheetah_plus)
 171                 return -ENODEV;
 172
 173         __asm__("rdpr %%ver, %0" : "=r" (ver));
 174         manuf = ((ver >> 48) & 0xffff);
 175         impl  = ((ver >> 32) & 0xffff);
 176
 177         if (manuf == CHEETAH_MANUF &&
 178             (impl == CHEETAH_IMPL ||
 179              impl == CHEETAH_PLUS_IMPL ||
 180              impl == JAGUAR_IMPL ||
 181              impl == PANTHER_IMPL)) {
 182                 struct cpufreq_driver *driver;
 183
 184                 ret = -ENOMEM;
 185                 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
 186                 if (!driver)
 187                         goto err_out;
 188
 189                 us3_freq_table = kzalloc((NR_CPUS * sizeof(*us3_freq_table)),
 190                         GFP_KERNEL);
 191                 if (!us3_freq_table)
 192                         goto err_out;
 193
 194                 driver->init = us3_freq_cpu_init;
 195                 driver->verify = cpufreq_generic_frequency_table_verify;
 196                 driver->target_index = us3_freq_target;
 197                 driver->get = us3_freq_get;
 198                 driver->exit = us3_freq_cpu_exit;
 199                 strcpy(driver->name, "UltraSPARC-III");
 200
 201                 cpufreq_us3_driver = driver;
 202                 ret = cpufreq_register_driver(driver);
 203                 if (ret)
 204                         goto err_out;
 205
 206                 return 0;
 207
 208 err_out:
 209                 if (driver) {
 210                         kfree(driver);
 211                         cpufreq_us3_driver = NULL;
 212                 }
 213                 kfree(us3_freq_table);
 214                 us3_freq_table = NULL;
 215                 return ret;
 216         }
 217
 218         return -ENODEV;
 219 }
 220
 221 static void __exit us3_freq_exit(void)
 222 {
 223         if (cpufreq_us3_driver) {
 224                 cpufreq_unregister_driver(cpufreq_us3_driver);
 225                 kfree(cpufreq_us3_driver);
 226                 cpufreq_us3_driver = NULL;
 227                 kfree(us3_freq_table);
 228                 us3_freq_table = NULL;
 229         }
 230 }
 231
 232 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
 233 MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
 234 MODULE_LICENSE("GPL");
 235
 236 module_init(us3_freq_init);
 237 module_exit(us3_freq_exit);