arch/blackfin/mach-common/cpufreq.c

   1 /*
   2  * File:         arch/blackfin/mach-common/cpufreq.c
   3  * Based on:
   4  * Author:
   5  *
   6  * Created:
   7  * Description:  Blackfin core clock scaling
   8  *
   9  * Modified:
  10  *               Copyright 2004-2008 Analog Devices Inc.
  11  *
  12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, see the file COPYING, or write
  26  * to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA      02110-1301      USA
  28  */
  29
  30 #include <linux/kernel.h>
  31 #include <linux/types.h>
  32 #include <linux/init.h>
  33 #include <linux/cpufreq.h>
  34 #include <linux/fs.h>
  35 #include <asm/blackfin.h>
  36 #include <asm/time.h>
  37
  38
  39 /* this is the table of CCLK frequencies, in Hz */
  40 /* .index is the entry in the auxillary dpm_state_table[] */
  41 static struct cpufreq_frequency_table bfin_freq_table[] = {
  42         {
  43                 .frequency = CPUFREQ_TABLE_END,
  44                 .index = 0,
  45         },
  46         {
  47                 .frequency = CPUFREQ_TABLE_END,
  48                 .index = 1,
  49         },
  50         {
  51                 .frequency = CPUFREQ_TABLE_END,
  52                 .index = 2,
  53         },
  54         {
  55                 .frequency = CPUFREQ_TABLE_END,
  56                 .index = 0,
  57         },
  58 };
  59
  60 static struct bfin_dpm_state {
  61         unsigned int csel; /* system clock divider */
  62         unsigned int tscale; /* change the divider on the core timer interrupt */
  63 } dpm_state_table[3];
  64
  65 /*
  66    normalized to maximum frequncy offset for CYCLES,
  67    used in time-ts cycles clock source, but could be used
  68    somewhere also.
  69  */
  70 unsigned long long __bfin_cycles_off;
  71 unsigned int __bfin_cycles_mod;
  72
  73 /**************************************************************************/
  74
  75 static unsigned int bfin_getfreq(unsigned int cpu)
  76 {
  77         /* The driver only support single cpu */
  78         if (cpu != 0)
  79                 return -1;
  80
  81         return get_cclk();
  82 }
  83
  84
  85 static int bfin_target(struct cpufreq_policy *policy,
  86                         unsigned int target_freq, unsigned int relation)
  87 {
  88         unsigned int index, plldiv, tscale;
  89         unsigned long flags, cclk_hz;
  90         struct cpufreq_freqs freqs;
  91         cycles_t cycles;
  92
  93         if (cpufreq_frequency_table_target(policy, bfin_freq_table,
  94                  target_freq, relation, &index))
  95                 return -EINVAL;
  96
  97         cclk_hz = bfin_freq_table[index].frequency;
  98
  99         freqs.old = bfin_getfreq(0);
 100         freqs.new = cclk_hz;
 101         freqs.cpu = 0;
 102
 103         pr_debug("cpufreq: changing cclk to %lu; target = %u, oldfreq = %u\n",
 104                  cclk_hz, target_freq, freqs.old);
 105
 106         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 107         local_irq_save(flags);
 108                 plldiv = (bfin_read_PLL_DIV() & SSEL) | dpm_state_table[index].csel;
 109                 tscale = dpm_state_table[index].tscale;
 110                 bfin_write_PLL_DIV(plldiv);
 111                 /* we have to adjust the core timer, because it is using cclk */
 112                 bfin_write_TSCALE(tscale);
 113                 cycles = get_cycles();
 114                 SSYNC();
 115         cycles += 10; /* ~10 cycles we loose after get_cycles() */
 116         __bfin_cycles_off += (cycles << __bfin_cycles_mod) - (cycles << index);
 117         __bfin_cycles_mod = index;
 118         local_irq_restore(flags);
 119         /* TODO: just test case for cycles clock source, remove later */
 120         pr_debug("cpufreq: done\n");
 121         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 122
 123         return 0;
 124 }
 125
 126 static int bfin_verify_speed(struct cpufreq_policy *policy)
 127 {
 128         return cpufreq_frequency_table_verify(policy, bfin_freq_table);
 129 }
 130
 131 static int __init __bfin_cpu_init(struct cpufreq_policy *policy)
 132 {
 133
 134         unsigned long cclk, sclk, csel, min_cclk;
 135         int index;
 136
 137         if (policy->cpu != 0)
 138                 return -EINVAL;
 139
 140         cclk = get_cclk();
 141         sclk = get_sclk();
 142
 143 #if ANOMALY_05000273 || (!defined(CONFIG_BF54x) && defined(CONFIG_BFIN_DCACHE))
 144         min_cclk = sclk * 2;
 145 #else
 146         min_cclk = sclk;
 147 #endif
 148         csel = ((bfin_read_PLL_DIV() & CSEL) >> 4);
 149
 150         for (index = 0;  (cclk >> index) >= min_cclk && csel <= 3; index++, csel++) {
 151                 bfin_freq_table[index].frequency = cclk >> index;
 152                 dpm_state_table[index].csel = csel << 4; /* Shift now into PLL_DIV bitpos */
 153                 dpm_state_table[index].tscale =  (TIME_SCALE / (1 << csel)) - 1;
 154
 155                 pr_debug("cpufreq: freq:%d csel:%d tscale:%d\n",
 156                                                  bfin_freq_table[index].frequency,
 157                                                  dpm_state_table[index].csel,
 158                                                  dpm_state_table[index].tscale);
 159         }
 160
 161         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 162
 163         policy->cpuinfo.transition_latency = (bfin_read_PLL_LOCKCNT() / (sclk / 1000000)) * 1000;
 164         /*Now ,only support one cpu */
 165         policy->cur = cclk;
 166         cpufreq_frequency_table_get_attr(bfin_freq_table, policy->cpu);
 167         return cpufreq_frequency_table_cpuinfo(policy, bfin_freq_table);
 168 }
 169
 170 static struct freq_attr *bfin_freq_attr[] = {
 171         &cpufreq_freq_attr_scaling_available_freqs,
 172         NULL,
 173 };
 174
 175 static struct cpufreq_driver bfin_driver = {
 176         .verify = bfin_verify_speed,
 177         .target = bfin_target,
 178         .get = bfin_getfreq,
 179         .init = __bfin_cpu_init,
 180         .name = "bfin cpufreq",
 181         .owner = THIS_MODULE,
 182         .attr = bfin_freq_attr,
 183 };
 184
 185 static int __init bfin_cpu_init(void)
 186 {
 187         return cpufreq_register_driver(&bfin_driver);
 188 }
 189
 190 static void __exit bfin_cpu_exit(void)
 191 {
 192         cpufreq_unregister_driver(&bfin_driver);
 193 }
 194
 195 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 196 MODULE_DESCRIPTION("cpufreq driver for Blackfin");
 197 MODULE_LICENSE("GPL");
 198
 199 module_init(bfin_cpu_init);
 200 module_exit(bfin_cpu_exit);