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