arch/powerpc/platforms/cell/cbe_cpufreq.c

   1 /*
   2  * cpufreq driver for the cell processor
   3  *
   4  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-2007
   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 <asm/machdep.h>
  25 #include <asm/of_platform.h>
  26 #include <asm/prom.h>
  27 #include <asm/cell-regs.h>
  28 #include "cbe_cpufreq.h"
  29
  30 static DEFINE_MUTEX(cbe_switch_mutex);
  31
  32
  33 /* the CBE supports an 8 step frequency scaling */
  34 static struct cpufreq_frequency_table cbe_freqs[] = {
  35         {1,     0},
  36         {2,     0},
  37         {3,     0},
  38         {4,     0},
  39         {5,     0},
  40         {6,     0},
  41         {8,     0},
  42         {10,    0},
  43         {0,     CPUFREQ_TABLE_END},
  44 };
  45
  46 /*
  47  * hardware specific functions
  48  */
  49
  50 static int set_pmode(unsigned int cpu, unsigned int slow_mode)
  51 {
  52         int rc;
  53
  54         if (cbe_cpufreq_has_pmi)
  55                 rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
  56         else
  57                 rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
  58
  59         pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
  60
  61         return rc;
  62 }
  63
  64 /*
  65  * cpufreq functions
  66  */
  67
  68 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
  69 {
  70         const u32 *max_freqp;
  71         u32 max_freq;
  72         int i, cur_pmode;
  73         struct device_node *cpu;
  74
  75         cpu = of_get_cpu_node(policy->cpu, NULL);
  76
  77         if (!cpu)
  78                 return -ENODEV;
  79
  80         pr_debug("init cpufreq on CPU %d\n", policy->cpu);
  81
  82         /*
  83          * Let's check we can actually get to the CELL regs
  84          */
  85         if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
  86             !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
  87                 pr_info("invalid CBE regs pointers for cpufreq\n");
  88                 return -EINVAL;
  89         }
  90
  91         max_freqp = of_get_property(cpu, "clock-frequency", NULL);
  92
  93         of_node_put(cpu);
  94
  95         if (!max_freqp)
  96                 return -EINVAL;
  97
  98         /* we need the freq in kHz */
  99         max_freq = *max_freqp / 1000;
 100
 101         pr_debug("max clock-frequency is at %u kHz\n", max_freq);
 102         pr_debug("initializing frequency table\n");
 103
 104         /* initialize frequency table */
 105         for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
 106                 cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index;
 107                 pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
 108         }
 109
 110         /* if DEBUG is enabled set_pmode() measures the latency
 111          * of a transition */
 112         policy->cpuinfo.transition_latency = 25000;
 113
 114         cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
 115         pr_debug("current pmode is at %d\n",cur_pmode);
 116
 117         policy->cur = cbe_freqs[cur_pmode].frequency;
 118
 119 #ifdef CONFIG_SMP
 120         policy->cpus = cpu_sibling_map[policy->cpu];
 121 #endif
 122
 123         cpufreq_frequency_table_get_attr(cbe_freqs, policy->cpu);
 124
 125         /* this ensures that policy->cpuinfo_min
 126          * and policy->cpuinfo_max are set correctly */
 127         return cpufreq_frequency_table_cpuinfo(policy, cbe_freqs);
 128 }
 129
 130 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 131 {
 132         cpufreq_frequency_table_put_attr(policy->cpu);
 133         return 0;
 134 }
 135
 136 static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
 137 {
 138         return cpufreq_frequency_table_verify(policy, cbe_freqs);
 139 }
 140
 141 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
 142                               unsigned int target_freq,
 143                               unsigned int relation)
 144 {
 145         int rc;
 146         struct cpufreq_freqs freqs;
 147         unsigned int cbe_pmode_new;
 148
 149         cpufreq_frequency_table_target(policy,
 150                                        cbe_freqs,
 151                                        target_freq,
 152                                        relation,
 153                                        &cbe_pmode_new);
 154
 155         freqs.old = policy->cur;
 156         freqs.new = cbe_freqs[cbe_pmode_new].frequency;
 157         freqs.cpu = policy->cpu;
 158
 159         mutex_lock(&cbe_switch_mutex);
 160         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 161
 162         pr_debug("setting frequency for cpu %d to %d kHz, " \
 163                  "1/%d of max frequency\n",
 164                  policy->cpu,
 165                  cbe_freqs[cbe_pmode_new].frequency,
 166                  cbe_freqs[cbe_pmode_new].index);
 167
 168         rc = set_pmode(policy->cpu, cbe_pmode_new);
 169
 170         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 171         mutex_unlock(&cbe_switch_mutex);
 172
 173         return rc;
 174 }
 175
 176 static struct cpufreq_driver cbe_cpufreq_driver = {
 177         .verify         = cbe_cpufreq_verify,
 178         .target         = cbe_cpufreq_target,
 179         .init           = cbe_cpufreq_cpu_init,
 180         .exit           = cbe_cpufreq_cpu_exit,
 181         .name           = "cbe-cpufreq",
 182         .owner          = THIS_MODULE,
 183         .flags          = CPUFREQ_CONST_LOOPS,
 184 };
 185
 186 /*
 187  * module init and destoy
 188  */
 189
 190 static int __init cbe_cpufreq_init(void)
 191 {
 192         if (!machine_is(cell))
 193                 return -ENODEV;
 194
 195         return cpufreq_register_driver(&cbe_cpufreq_driver);
 196 }
 197
 198 static void __exit cbe_cpufreq_exit(void)
 199 {
 200         cpufreq_unregister_driver(&cbe_cpufreq_driver);
 201 }
 202
 203 module_init(cbe_cpufreq_init);
 204 module_exit(cbe_cpufreq_exit);
 205
 206 MODULE_LICENSE("GPL");
 207 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");