arch/sh/kernel/cpufreq.c

   1 /*
   2  * arch/sh/kernel/cpufreq.c
   3  *
   4  * cpufreq driver for the SuperH processors.
   5  *
   6  * Copyright (C) 2002, 2003, 2004, 2005 Paul Mundt
   7  * Copyright (C) 2002 M. R. Brown
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the
  11  * Free Software Foundation; either version 2 of the License, or (at your
  12  * option) any later version.
  13  */
  14 #include <linux/types.h>
  15 #include <linux/cpufreq.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/slab.h>
  19 #include <linux/init.h>
  20 #include <linux/delay.h>
  21 #include <linux/cpumask.h>
  22 #include <linux/smp.h>
  23 #include <linux/sched.h>        /* set_cpus_allowed() */
  24
  25 #include <asm/processor.h>
  26 #include <asm/watchdog.h>
  27 #include <asm/freq.h>
  28 #include <asm/io.h>
  29
  30 /*
  31  * For SuperH, each policy change requires that we change the IFC, BFC, and
  32  * PFC at the same time.  Here we define sane values that won't trash the
  33  * system.
  34  *
  35  * Note the max set is computed at runtime, we use the divisors that we booted
  36  * with to setup our maximum operating frequencies.
  37  */
  38 struct clock_set {
  39         unsigned int ifc;
  40         unsigned int bfc;
  41         unsigned int pfc;
  42 } clock_sets[] = {
  43 #if defined(CONFIG_CPU_SH3) || defined(CONFIG_CPU_SH2)
  44         { 0, 0, 0 },    /* not implemented yet */
  45 #elif defined(CONFIG_CPU_SH4)
  46         { 4, 8, 8 },    /* min - IFC: 1/4, BFC: 1/8, PFC: 1/8 */
  47         { 1, 2, 2 },    /* max - IFC: 1, BFC: 1/2, PFC: 1/2 */
  48 #endif
  49 };
  50
  51 #define MIN_CLOCK_SET   0
  52 #define MAX_CLOCK_SET   (ARRAY_SIZE(clock_sets) - 1)
  53
  54 /*
  55  * For the time being, we only support two frequencies, which in turn are
  56  * aimed at the POWERSAVE and PERFORMANCE policies, which in turn are derived
  57  * directly from the respective min/max clock sets. Technically we could
  58  * support a wider range of frequencies, but these vary far too much for each
  59  * CPU subtype (and we'd have to construct a frequency table for each subtype).
  60  *
  61  * Maybe something to implement in the future..
  62  */
  63 #define SH_FREQ_MAX     0
  64 #define SH_FREQ_MIN     1
  65
  66 static struct cpufreq_frequency_table sh_freqs[] = {
  67         { SH_FREQ_MAX,  0 },
  68         { SH_FREQ_MIN,  0 },
  69         { 0,            CPUFREQ_TABLE_END },
  70 };
  71
  72 static void sh_cpufreq_update_clocks(unsigned int set)
  73 {
  74         current_cpu_data.cpu_clock = current_cpu_data.master_clock / clock_sets[set].ifc;
  75         current_cpu_data.bus_clock = current_cpu_data.master_clock / clock_sets[set].bfc;
  76         current_cpu_data.module_clock = current_cpu_data.master_clock / clock_sets[set].pfc;
  77         current_cpu_data.loops_per_jiffy = loops_per_jiffy;
  78 }
  79
  80 /* XXX: This needs to be split out per CPU and CPU subtype. */
  81 /*
  82  * Here we notify other drivers of the proposed change and the final change.
  83  */
  84 static int sh_cpufreq_setstate(unsigned int cpu, unsigned int set)
  85 {
  86         unsigned short frqcr = ctrl_inw(FRQCR);
  87         cpumask_t cpus_allowed;
  88         struct cpufreq_freqs freqs;
  89
  90         if (!cpu_online(cpu))
  91                 return -ENODEV;
  92
  93         cpus_allowed = current->cpus_allowed;
  94         set_cpus_allowed(current, cpumask_of_cpu(cpu));
  95
  96         BUG_ON(smp_processor_id() != cpu);
  97
  98         freqs.cpu = cpu;
  99         freqs.old = current_cpu_data.cpu_clock / 1000;
 100         freqs.new = (current_cpu_data.master_clock / clock_sets[set].ifc) / 1000;
 101
 102         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 103 #if defined(CONFIG_CPU_SH3)
 104         frqcr |= (newstate & 0x4000) << 14;
 105         frqcr |= (newstate & 0x000c) <<  2;
 106 #elif defined(CONFIG_CPU_SH4)
 107         /*
 108          * FRQCR.PLL2EN is 1, we need to allow the PLL to stabilize by
 109          * initializing the WDT.
 110          */
 111         if (frqcr & (1 << 9)) {
 112                 __u8 csr;
 113
 114                 /*
 115                  * Set the overflow period to the highest available,
 116                  * in this case a 1/4096 division ratio yields a 5.25ms
 117                  * overflow period. See asm-sh/watchdog.h for more
 118                  * information and a range of other divisors.
 119                  */
 120                 csr = sh_wdt_read_csr();
 121                 csr |= WTCSR_CKS_4096;
 122                 sh_wdt_write_csr(csr);
 123
 124                 sh_wdt_write_cnt(0);
 125         }
 126         frqcr &= 0x0e00;        /* Clear ifc, bfc, pfc */
 127         frqcr |= get_ifc_value(clock_sets[set].ifc) << 6;
 128         frqcr |= get_bfc_value(clock_sets[set].bfc) << 3;
 129         frqcr |= get_pfc_value(clock_sets[set].pfc);
 130 #endif
 131         ctrl_outw(frqcr, FRQCR);
 132         sh_cpufreq_update_clocks(set);
 133
 134         set_cpus_allowed(current, cpus_allowed);
 135         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 136
 137         return 0;
 138 }
 139
 140 static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
 141 {
 142         unsigned int min_freq, max_freq;
 143         unsigned int ifc, bfc, pfc;
 144
 145         if (!cpu_online(policy->cpu))
 146                 return -ENODEV;
 147
 148         /* Update our maximum clock set */
 149         get_current_frequency_divisors(&ifc, &bfc, &pfc);
 150         clock_sets[MAX_CLOCK_SET].ifc = ifc;
 151         clock_sets[MAX_CLOCK_SET].bfc = bfc;
 152         clock_sets[MAX_CLOCK_SET].pfc = pfc;
 153
 154         /* Convert from Hz to kHz */
 155         max_freq = current_cpu_data.cpu_clock / 1000;
 156         min_freq = (current_cpu_data.master_clock / clock_sets[MIN_CLOCK_SET].ifc) / 1000;
 157
 158         sh_freqs[SH_FREQ_MAX].frequency = max_freq;
 159         sh_freqs[SH_FREQ_MIN].frequency = min_freq;
 160
 161         /* cpuinfo and default policy values */
 162         policy->governor                   = CPUFREQ_DEFAULT_GOVERNOR;
 163         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 164         policy->cur                        = max_freq;
 165
 166         return cpufreq_frequency_table_cpuinfo(policy, &sh_freqs[0]);
 167 }
 168
 169 static int sh_cpufreq_verify(struct cpufreq_policy *policy)
 170 {
 171         return cpufreq_frequency_table_verify(policy, &sh_freqs[0]);
 172 }
 173
 174 static int sh_cpufreq_target(struct cpufreq_policy *policy,
 175                              unsigned int target_freq,
 176                              unsigned int relation)
 177 {
 178         unsigned int set, idx = 0;
 179
 180         if (cpufreq_frequency_table_target(policy, &sh_freqs[0], target_freq, relation, &idx))
 181                 return -EINVAL;
 182
 183         set = (idx == SH_FREQ_MIN) ? MIN_CLOCK_SET : MAX_CLOCK_SET;
 184
 185         sh_cpufreq_setstate(policy->cpu, set);
 186
 187         return 0;
 188 }
 189
 190 static struct cpufreq_driver sh_cpufreq_driver = {
 191         .owner          = THIS_MODULE,
 192         .name           = "SH cpufreq",
 193         .init           = sh_cpufreq_cpu_init,
 194         .verify         = sh_cpufreq_verify,
 195         .target         = sh_cpufreq_target,
 196 };
 197
 198 static int __init sh_cpufreq_init(void)
 199 {
 200         if (!current_cpu_data.cpu_clock)
 201                 return -EINVAL;
 202         if (cpufreq_register_driver(&sh_cpufreq_driver))
 203                 return -EINVAL;
 204
 205         return 0;
 206 }
 207
 208 static void __exit sh_cpufreq_exit(void)
 209 {
 210         cpufreq_unregister_driver(&sh_cpufreq_driver);
 211 }
 212
 213 module_init(sh_cpufreq_init);
 214 module_exit(sh_cpufreq_exit);
 215
 216 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 217 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 218 MODULE_LICENSE("GPL");
 219