arch/powerpc/platforms/cell/cbe_cpufreq.c

   1 /*
   2  * cpufreq driver for the cell processor
   3  *
   4  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
   5  *
   6  * Author: Christian Krafft <krafft@de.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #include <linux/cpufreq.h>
  24 #include <linux/timer.h>
  25
  26 #include <asm/hw_irq.h>
  27 #include <asm/io.h>
  28 #include <asm/processor.h>
  29 #include <asm/prom.h>
  30 #include <asm/time.h>
  31
  32 #include "cbe_regs.h"
  33
  34 static DEFINE_MUTEX(cbe_switch_mutex);
  35
  36
  37 /* the CBE supports an 8 step frequency scaling */
  38 static struct cpufreq_frequency_table cbe_freqs[] = {
  39         {1,     0},
  40         {2,     0},
  41         {3,     0},
  42         {4,     0},
  43         {5,     0},
  44         {6,     0},
  45         {8,     0},
  46         {10,    0},
  47         {0,     CPUFREQ_TABLE_END},
  48 };
  49
  50 /* to write to MIC register */
  51 static u64 MIC_Slow_Fast_Timer_table[] = {
  52         [0 ... 7] = 0x007fc00000000000ull,
  53 };
  54
  55 /* more values for the MIC */
  56 static u64 MIC_Slow_Next_Timer_table[] = {
  57         0x0000240000000000ull,
  58         0x0000268000000000ull,
  59         0x000029C000000000ull,
  60         0x00002D0000000000ull,
  61         0x0000300000000000ull,
  62         0x0000334000000000ull,
  63         0x000039C000000000ull,
  64         0x00003FC000000000ull,
  65 };
  66
  67 /*
  68  * hardware specific functions
  69  */
  70
  71 static int get_pmode(int cpu)
  72 {
  73         int ret;
  74         struct cbe_pmd_regs __iomem *pmd_regs;
  75
  76         pmd_regs = cbe_get_cpu_pmd_regs(cpu);
  77         ret = in_be64(&pmd_regs->pmsr) & 0x07;
  78
  79         return ret;
  80 }
  81
  82 static int set_pmode(int cpu, unsigned int pmode)
  83 {
  84         struct cbe_pmd_regs __iomem *pmd_regs;
  85         struct cbe_mic_tm_regs __iomem *mic_tm_regs;
  86         u64 flags;
  87         u64 value;
  88
  89         local_irq_save(flags);
  90
  91         mic_tm_regs = cbe_get_cpu_mic_tm_regs(cpu);
  92         pmd_regs = cbe_get_cpu_pmd_regs(cpu);
  93
  94         pr_debug("pm register is mapped at %p\n", &pmd_regs->pmcr);
  95         pr_debug("mic register is mapped at %p\n", &mic_tm_regs->slow_fast_timer_0);
  96
  97         out_be64(&mic_tm_regs->slow_fast_timer_0, MIC_Slow_Fast_Timer_table[pmode]);
  98         out_be64(&mic_tm_regs->slow_fast_timer_1, MIC_Slow_Fast_Timer_table[pmode]);
  99
 100         out_be64(&mic_tm_regs->slow_next_timer_0, MIC_Slow_Next_Timer_table[pmode]);
 101         out_be64(&mic_tm_regs->slow_next_timer_1, MIC_Slow_Next_Timer_table[pmode]);
 102
 103         value = in_be64(&pmd_regs->pmcr);
 104         /* set bits to zero */
 105         value &= 0xFFFFFFFFFFFFFFF8ull;
 106         /* set bits to next pmode */
 107         value |= pmode;
 108
 109         out_be64(&pmd_regs->pmcr, value);
 110
 111         /* wait until new pmode appears in status register */
 112         value = in_be64(&pmd_regs->pmsr) & 0x07;
 113         while(value != pmode) {
 114                 cpu_relax();
 115                 value = in_be64(&pmd_regs->pmsr) & 0x07;
 116         }
 117
 118         local_irq_restore(flags);
 119
 120         return 0;
 121 }
 122
 123 /*
 124  * cpufreq functions
 125  */
 126
 127 static int cbe_cpufreq_cpu_init (struct cpufreq_policy *policy)
 128 {
 129         const u32 *max_freqp;
 130         u32 max_freq;
 131         int i, cur_pmode;
 132         struct device_node *cpu;
 133
 134         cpu = of_get_cpu_node(policy->cpu, NULL);
 135
 136         if(!cpu)
 137                 return -ENODEV;
 138
 139         pr_debug("init cpufreq on CPU %d\n", policy->cpu);
 140
 141         max_freqp = of_get_property(cpu, "clock-frequency", NULL);
 142
 143         if (!max_freqp)
 144                 return -EINVAL;
 145
 146         // we need the freq in kHz
 147         max_freq = *max_freqp / 1000;
 148
 149         pr_debug("max clock-frequency is at %u kHz\n", max_freq);
 150         pr_debug("initializing frequency table\n");
 151
 152         // initialize frequency table
 153         for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
 154                 cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index;
 155                 pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
 156         }
 157
 158         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 159         /* if DEBUG is enabled set_pmode() measures the correct latency of a transition */
 160         policy->cpuinfo.transition_latency = 25000;
 161
 162         cur_pmode = get_pmode(policy->cpu);
 163         pr_debug("current pmode is at %d\n",cur_pmode);
 164
 165         policy->cur = cbe_freqs[cur_pmode].frequency;
 166
 167 #ifdef CONFIG_SMP
 168         policy->cpus = cpu_sibling_map[policy->cpu];
 169 #endif
 170
 171         cpufreq_frequency_table_get_attr (cbe_freqs, policy->cpu);
 172
 173         /* this ensures that policy->cpuinfo_min and policy->cpuinfo_max are set correctly */
 174         return cpufreq_frequency_table_cpuinfo (policy, cbe_freqs);
 175 }
 176
 177 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 178 {
 179         cpufreq_frequency_table_put_attr(policy->cpu);
 180         return 0;
 181 }
 182
 183 static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
 184 {
 185         return cpufreq_frequency_table_verify(policy, cbe_freqs);
 186 }
 187
 188
 189 static int cbe_cpufreq_target(struct cpufreq_policy *policy, unsigned int target_freq,
 190                             unsigned int relation)
 191 {
 192         int rc;
 193         struct cpufreq_freqs freqs;
 194         int cbe_pmode_new;
 195
 196         cpufreq_frequency_table_target(policy,
 197                                        cbe_freqs,
 198                                        target_freq,
 199                                        relation,
 200                                        &cbe_pmode_new);
 201
 202         freqs.old = policy->cur;
 203         freqs.new = cbe_freqs[cbe_pmode_new].frequency;
 204         freqs.cpu = policy->cpu;
 205
 206         mutex_lock (&cbe_switch_mutex);
 207         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 208
 209         pr_debug("setting frequency for cpu %d to %d kHz, 1/%d of max frequency\n",
 210                  policy->cpu,
 211                  cbe_freqs[cbe_pmode_new].frequency,
 212                  cbe_freqs[cbe_pmode_new].index);
 213
 214         rc = set_pmode(policy->cpu, cbe_pmode_new);
 215         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 216         mutex_unlock(&cbe_switch_mutex);
 217
 218         return rc;
 219 }
 220
 221 static struct cpufreq_driver cbe_cpufreq_driver = {
 222         .verify         = cbe_cpufreq_verify,
 223         .target         = cbe_cpufreq_target,
 224         .init           = cbe_cpufreq_cpu_init,
 225         .exit           = cbe_cpufreq_cpu_exit,
 226         .name           = "cbe-cpufreq",
 227         .owner          = THIS_MODULE,
 228         .flags          = CPUFREQ_CONST_LOOPS,
 229 };
 230
 231 /*
 232  * module init and destoy
 233  */
 234
 235 static int __init cbe_cpufreq_init(void)
 236 {
 237         return cpufreq_register_driver(&cbe_cpufreq_driver);
 238 }
 239
 240 static void __exit cbe_cpufreq_exit(void)
 241 {
 242         cpufreq_unregister_driver(&cbe_cpufreq_driver);
 243 }
 244
 245 module_init(cbe_cpufreq_init);
 246 module_exit(cbe_cpufreq_exit);
 247
 248 MODULE_LICENSE("GPL");
 249 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");