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         struct cpufreq_freqs freqs;
 102
 103         cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
 104         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 105
 106         new_freq = sparc64_get_clock_tick(cpu) / 1000;
 107         switch (index) {
 108         case 0:
 109                 new_bits = SAFARI_CFG_DIV_1;
 110                 new_freq /= 1;
 111                 break;
 112         case 1:
 113                 new_bits = SAFARI_CFG_DIV_2;
 114                 new_freq /= 2;
 115                 break;
 116         case 2:
 117                 new_bits = SAFARI_CFG_DIV_32;
 118                 new_freq /= 32;
 119                 break;
 120
 121         default:
 122                 BUG();
 123         }
 124
 125         reg = read_safari_cfg();
 126
 127         freqs.old = get_current_freq(cpu, reg);
 128         freqs.new = new_freq;
 129         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 130
 131         reg &= ~SAFARI_CFG_DIV_MASK;
 132         reg |= new_bits;
 133         write_safari_cfg(reg);
 134
 135         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 136
 137         set_cpus_allowed_ptr(current, &cpus_allowed);
 138
 139         return 0;
 140 }
 141
 142 static int __init us3_freq_cpu_init(struct cpufreq_policy *policy)
 143 {
 144         unsigned int cpu = policy->cpu;
 145         unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
 146         struct cpufreq_frequency_table *table =
 147                 &us3_freq_table[cpu].table[0];
 148
 149         table[0].driver_data = 0;
 150         table[0].frequency = clock_tick / 1;
 151         table[1].driver_data = 1;
 152         table[1].frequency = clock_tick / 2;
 153         table[2].driver_data = 2;
 154         table[2].frequency = clock_tick / 32;
 155         table[3].driver_data = 0;
 156         table[3].frequency = CPUFREQ_TABLE_END;
 157
 158         policy->cpuinfo.transition_latency = 0;
 159         policy->cur = clock_tick;
 160
 161         return cpufreq_table_validate_and_show(policy, table);
 162 }
 163
 164 static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
 165 {
 166         if (cpufreq_us3_driver) {
 167                 cpufreq_frequency_table_put_attr(policy->cpu);
 168                 us3_freq_target(policy, 0);
 169         }
 170
 171         return 0;
 172 }
 173
 174 static int __init us3_freq_init(void)
 175 {
 176         unsigned long manuf, impl, ver;
 177         int ret;
 178
 179         if (tlb_type != cheetah && tlb_type != cheetah_plus)
 180                 return -ENODEV;
 181
 182         __asm__("rdpr %%ver, %0" : "=r" (ver));
 183         manuf = ((ver >> 48) & 0xffff);
 184         impl  = ((ver >> 32) & 0xffff);
 185
 186         if (manuf == CHEETAH_MANUF &&
 187             (impl == CHEETAH_IMPL ||
 188              impl == CHEETAH_PLUS_IMPL ||
 189              impl == JAGUAR_IMPL ||
 190              impl == PANTHER_IMPL)) {
 191                 struct cpufreq_driver *driver;
 192
 193                 ret = -ENOMEM;
 194                 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
 195                 if (!driver)
 196                         goto err_out;
 197
 198                 us3_freq_table = kzalloc((NR_CPUS * sizeof(*us3_freq_table)),
 199                         GFP_KERNEL);
 200                 if (!us3_freq_table)
 201                         goto err_out;
 202
 203                 driver->init = us3_freq_cpu_init;
 204                 driver->verify = cpufreq_generic_frequency_table_verify;
 205                 driver->target_index = us3_freq_target;
 206                 driver->get = us3_freq_get;
 207                 driver->exit = us3_freq_cpu_exit;
 208                 strcpy(driver->name, "UltraSPARC-III");
 209
 210                 cpufreq_us3_driver = driver;
 211                 ret = cpufreq_register_driver(driver);
 212                 if (ret)
 213                         goto err_out;
 214
 215                 return 0;
 216
 217 err_out:
 218                 if (driver) {
 219                         kfree(driver);
 220                         cpufreq_us3_driver = NULL;
 221                 }
 222                 kfree(us3_freq_table);
 223                 us3_freq_table = NULL;
 224                 return ret;
 225         }
 226
 227         return -ENODEV;
 228 }
 229
 230 static void __exit us3_freq_exit(void)
 231 {
 232         if (cpufreq_us3_driver) {
 233                 cpufreq_unregister_driver(cpufreq_us3_driver);
 234                 kfree(cpufreq_us3_driver);
 235                 cpufreq_us3_driver = NULL;
 236                 kfree(us3_freq_table);
 237                 us3_freq_table = NULL;
 238         }
 239 }
 240
 241 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
 242 MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
 243 MODULE_LICENSE("GPL");
 244
 245 module_init(us3_freq_init);
 246 module_exit(us3_freq_exit);