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