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 /* the CBE supports an 8 step frequency scaling */
  34 static struct cpufreq_frequency_table cbe_freqs[] = {
  35         {0, 1,  0},
  36         {0, 2,  0},
  37         {0, 3,  0},
  38         {0, 4,  0},
  39         {0, 5,  0},
  40         {0, 6,  0},
  41         {0, 8,  0},
  42         {0, 10, 0},
  43         {0, 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         struct cpufreq_frequency_table *pos;
  71         const u32 *max_freqp;
  72         u32 max_freq;
  73         int cur_pmode;
  74         struct device_node *cpu;
  75
  76         cpu = of_get_cpu_node(policy->cpu, NULL);
  77
  78         if (!cpu)
  79                 return -ENODEV;
  80
  81         pr_debug("init cpufreq on CPU %d\n", policy->cpu);
  82
  83         /*
  84          * Let's check we can actually get to the CELL regs
  85          */
  86         if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
  87             !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
  88                 pr_info("invalid CBE regs pointers for cpufreq\n");
  89                 of_node_put(cpu);
  90                 return -EINVAL;
  91         }
  92
  93         max_freqp = of_get_property(cpu, "clock-frequency", NULL);
  94
  95         of_node_put(cpu);
  96
  97         if (!max_freqp)
  98                 return -EINVAL;
  99
 100         /* we need the freq in kHz */
 101         max_freq = *max_freqp / 1000;
 102
 103         pr_debug("max clock-frequency is at %u kHz\n", max_freq);
 104         pr_debug("initializing frequency table\n");
 105
 106         /* initialize frequency table */
 107         cpufreq_for_each_entry(pos, cbe_freqs) {
 108                 pos->frequency = max_freq / pos->driver_data;
 109                 pr_debug("%d: %d\n", (int)(pos - cbe_freqs), pos->frequency);
 110         }
 111
 112         /* if DEBUG is enabled set_pmode() measures the latency
 113          * of a transition */
 114         policy->cpuinfo.transition_latency = 25000;
 115
 116         cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
 117         pr_debug("current pmode is at %d\n",cur_pmode);
 118
 119         policy->cur = cbe_freqs[cur_pmode].frequency;
 120
 121 #ifdef CONFIG_SMP
 122         cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
 123 #endif
 124
 125         /* this ensures that policy->cpuinfo_min
 126          * and policy->cpuinfo_max are set correctly */
 127         return cpufreq_table_validate_and_show(policy, cbe_freqs);
 128 }
 129
 130 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
 131                               unsigned int cbe_pmode_new)
 132 {
 133         pr_debug("setting frequency for cpu %d to %d kHz, " \
 134                  "1/%d of max frequency\n",
 135                  policy->cpu,
 136                  cbe_freqs[cbe_pmode_new].frequency,
 137                  cbe_freqs[cbe_pmode_new].driver_data);
 138
 139         return set_pmode(policy->cpu, cbe_pmode_new);
 140 }
 141
 142 static struct cpufreq_driver cbe_cpufreq_driver = {
 143         .verify         = cpufreq_generic_frequency_table_verify,
 144         .target_index   = cbe_cpufreq_target,
 145         .init           = cbe_cpufreq_cpu_init,
 146         .name           = "cbe-cpufreq",
 147         .flags          = CPUFREQ_CONST_LOOPS,
 148 };
 149
 150 /*
 151  * module init and destoy
 152  */
 153
 154 static int __init cbe_cpufreq_init(void)
 155 {
 156         if (!machine_is(cell))
 157                 return -ENODEV;
 158
 159         return cpufreq_register_driver(&cbe_cpufreq_driver);
 160 }
 161
 162 static void __exit cbe_cpufreq_exit(void)
 163 {
 164         cpufreq_unregister_driver(&cbe_cpufreq_driver);
 165 }
 166
 167 module_init(cbe_cpufreq_init);
 168 module_exit(cbe_cpufreq_exit);
 169
 170 MODULE_LICENSE("GPL");
 171 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");