arch/blackfin/mach-common/cpufreq.c

   1 /*
   2  * Blackfin core clock scaling
   3  *
   4  * Copyright 2008-2009 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/types.h>
  11 #include <linux/init.h>
  12 #include <linux/cpufreq.h>
  13 #include <linux/fs.h>
  14 #include <asm/blackfin.h>
  15 #include <asm/time.h>
  16 #include <asm/dpmc.h>
  17
  18 /* this is the table of CCLK frequencies, in Hz */
  19 /* .index is the entry in the auxillary dpm_state_table[] */
  20 static struct cpufreq_frequency_table bfin_freq_table[] = {
  21         {
  22                 .frequency = CPUFREQ_TABLE_END,
  23                 .index = 0,
  24         },
  25         {
  26                 .frequency = CPUFREQ_TABLE_END,
  27                 .index = 1,
  28         },
  29         {
  30                 .frequency = CPUFREQ_TABLE_END,
  31                 .index = 2,
  32         },
  33         {
  34                 .frequency = CPUFREQ_TABLE_END,
  35                 .index = 0,
  36         },
  37 };
  38
  39 static struct bfin_dpm_state {
  40         unsigned int csel; /* system clock divider */
  41         unsigned int tscale; /* change the divider on the core timer interrupt */
  42 } dpm_state_table[3];
  43
  44 /*
  45    normalized to maximum frequncy offset for CYCLES,
  46    used in time-ts cycles clock source, but could be used
  47    somewhere also.
  48  */
  49 unsigned long long __bfin_cycles_off;
  50 unsigned int __bfin_cycles_mod;
  51
  52 /**************************************************************************/
  53
  54 static unsigned int bfin_getfreq_khz(unsigned int cpu)
  55 {
  56         /* The driver only support single cpu */
  57         if (cpu != 0)
  58                 return -1;
  59
  60         return get_cclk() / 1000;
  61 }
  62
  63
  64 static int bfin_target(struct cpufreq_policy *policy,
  65                         unsigned int target_freq, unsigned int relation)
  66 {
  67         unsigned int index, plldiv, tscale;
  68         unsigned long flags, cclk_hz;
  69         struct cpufreq_freqs freqs;
  70         cycles_t cycles;
  71
  72         if (cpufreq_frequency_table_target(policy, bfin_freq_table,
  73                  target_freq, relation, &index))
  74                 return -EINVAL;
  75
  76         cclk_hz = bfin_freq_table[index].frequency;
  77
  78         freqs.old = bfin_getfreq_khz(0);
  79         freqs.new = cclk_hz;
  80         freqs.cpu = 0;
  81
  82         pr_debug("cpufreq: changing cclk to %lu; target = %u, oldfreq = %u\n",
  83                  cclk_hz, target_freq, freqs.old);
  84
  85         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  86         local_irq_save_hw(flags);
  87                 plldiv = (bfin_read_PLL_DIV() & SSEL) | dpm_state_table[index].csel;
  88                 tscale = dpm_state_table[index].tscale;
  89                 bfin_write_PLL_DIV(plldiv);
  90                 /* we have to adjust the core timer, because it is using cclk */
  91                 bfin_write_TSCALE(tscale);
  92                 cycles = get_cycles();
  93                 SSYNC();
  94         cycles += 10; /* ~10 cycles we lose after get_cycles() */
  95         __bfin_cycles_off += (cycles << __bfin_cycles_mod) - (cycles << index);
  96         __bfin_cycles_mod = index;
  97         local_irq_restore_hw(flags);
  98         /* TODO: just test case for cycles clock source, remove later */
  99         pr_debug("cpufreq: done\n");
 100         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 101
 102         return 0;
 103 }
 104
 105 static int bfin_verify_speed(struct cpufreq_policy *policy)
 106 {
 107         return cpufreq_frequency_table_verify(policy, bfin_freq_table);
 108 }
 109
 110 static int __init __bfin_cpu_init(struct cpufreq_policy *policy)
 111 {
 112
 113         unsigned long cclk, sclk, csel, min_cclk;
 114         int index;
 115
 116         if (policy->cpu != 0)
 117                 return -EINVAL;
 118
 119         cclk = get_cclk() / 1000;
 120         sclk = get_sclk() / 1000;
 121
 122 #if ANOMALY_05000273 || ANOMALY_05000274 || \
 123         (!defined(CONFIG_BF54x) && defined(CONFIG_BFIN_EXTMEM_DCACHEABLE))
 124         min_cclk = sclk * 2;
 125 #else
 126         min_cclk = sclk;
 127 #endif
 128         csel = ((bfin_read_PLL_DIV() & CSEL) >> 4);
 129
 130         for (index = 0;  (cclk >> index) >= min_cclk && csel <= 3; index++, csel++) {
 131                 bfin_freq_table[index].frequency = cclk >> index;
 132                 dpm_state_table[index].csel = csel << 4; /* Shift now into PLL_DIV bitpos */
 133                 dpm_state_table[index].tscale =  (TIME_SCALE / (1 << csel)) - 1;
 134
 135                 pr_debug("cpufreq: freq:%d csel:0x%x tscale:%d\n",
 136                                                  bfin_freq_table[index].frequency,
 137                                                  dpm_state_table[index].csel,
 138                                                  dpm_state_table[index].tscale);
 139         }
 140
 141         policy->cpuinfo.transition_latency = 50000; /* 50us assumed */
 142
 143         /*Now ,only support one cpu */
 144         policy->cur = cclk;
 145         cpufreq_frequency_table_get_attr(bfin_freq_table, policy->cpu);
 146         return cpufreq_frequency_table_cpuinfo(policy, bfin_freq_table);
 147 }
 148
 149 static struct freq_attr *bfin_freq_attr[] = {
 150         &cpufreq_freq_attr_scaling_available_freqs,
 151         NULL,
 152 };
 153
 154 static struct cpufreq_driver bfin_driver = {
 155         .verify = bfin_verify_speed,
 156         .target = bfin_target,
 157         .get = bfin_getfreq_khz,
 158         .init = __bfin_cpu_init,
 159         .name = "bfin cpufreq",
 160         .owner = THIS_MODULE,
 161         .attr = bfin_freq_attr,
 162 };
 163
 164 static int __init bfin_cpu_init(void)
 165 {
 166         return cpufreq_register_driver(&bfin_driver);
 167 }
 168
 169 static void __exit bfin_cpu_exit(void)
 170 {
 171         cpufreq_unregister_driver(&bfin_driver);
 172 }
 173
 174 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 175 MODULE_DESCRIPTION("cpufreq driver for Blackfin");
 176 MODULE_LICENSE("GPL");
 177
 178 module_init(bfin_cpu_init);
 179 module_exit(bfin_cpu_exit);