drivers/cpufreq/blackfin-cpufreq.c

   1 /*
   2  * Blackfin core clock scaling
   3  *
   4  * Copyright 2008-2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/types.h>
  12 #include <linux/init.h>
  13 #include <linux/clk.h>
  14 #include <linux/cpufreq.h>
  15 #include <linux/fs.h>
  16 #include <linux/delay.h>
  17 #include <asm/blackfin.h>
  18 #include <asm/time.h>
  19 #include <asm/dpmc.h>
  20
  21
  22 /* this is the table of CCLK frequencies, in Hz */
  23 /* .driver_data is the entry in the auxiliary dpm_state_table[] */
  24 static struct cpufreq_frequency_table bfin_freq_table[] = {
  25         {
  26                 .frequency = CPUFREQ_TABLE_END,
  27                 .driver_data = 0,
  28         },
  29         {
  30                 .frequency = CPUFREQ_TABLE_END,
  31                 .driver_data = 1,
  32         },
  33         {
  34                 .frequency = CPUFREQ_TABLE_END,
  35                 .driver_data = 2,
  36         },
  37         {
  38                 .frequency = CPUFREQ_TABLE_END,
  39                 .driver_data = 0,
  40         },
  41 };
  42
  43 static struct bfin_dpm_state {
  44         unsigned int csel; /* system clock divider */
  45         unsigned int tscale; /* change the divider on the core timer interrupt */
  46 } dpm_state_table[3];
  47
  48 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
  49 /*
  50  * normalized to maximum frequency offset for CYCLES,
  51  * used in time-ts cycles clock source, but could be used
  52  * somewhere also.
  53  */
  54 unsigned long long __bfin_cycles_off;
  55 unsigned int __bfin_cycles_mod;
  56 #endif
  57
  58 /**************************************************************************/
  59 static void __init bfin_init_tables(unsigned long cclk, unsigned long sclk)
  60 {
  61
  62         unsigned long csel, min_cclk;
  63         int index;
  64
  65         /* Anomaly 273 seems to still exist on non-BF54x w/dcache turned on */
  66 #if ANOMALY_05000273 || ANOMALY_05000274 || \
  67         (!(defined(CONFIG_BF54x) || defined(CONFIG_BF60x)) \
  68         && defined(CONFIG_BFIN_EXTMEM_DCACHEABLE))
  69         min_cclk = sclk * 2;
  70 #else
  71         min_cclk = sclk;
  72 #endif
  73
  74 #ifndef CONFIG_BF60x
  75         csel = ((bfin_read_PLL_DIV() & CSEL) >> 4);
  76 #else
  77         csel = bfin_read32(CGU0_DIV) & 0x1F;
  78 #endif
  79
  80         for (index = 0;  (cclk >> index) >= min_cclk && csel <= 3 && index < 3; index++, csel++) {
  81                 bfin_freq_table[index].frequency = cclk >> index;
  82 #ifndef CONFIG_BF60x
  83                 dpm_state_table[index].csel = csel << 4; /* Shift now into PLL_DIV bitpos */
  84 #else
  85                 dpm_state_table[index].csel = csel;
  86 #endif
  87                 dpm_state_table[index].tscale =  (TIME_SCALE >> index) - 1;
  88
  89                 pr_debug("cpufreq: freq:%d csel:0x%x tscale:%d\n",
  90                                                  bfin_freq_table[index].frequency,
  91                                                  dpm_state_table[index].csel,
  92                                                  dpm_state_table[index].tscale);
  93         }
  94         return;
  95 }
  96
  97 static void bfin_adjust_core_timer(void *info)
  98 {
  99         unsigned int tscale;
 100         unsigned int index = *(unsigned int *)info;
 101
 102         /* we have to adjust the core timer, because it is using cclk */
 103         tscale = dpm_state_table[index].tscale;
 104         bfin_write_TSCALE(tscale);
 105         return;
 106 }
 107
 108 static unsigned int bfin_getfreq_khz(unsigned int cpu)
 109 {
 110         /* Both CoreA/B have the same core clock */
 111         return get_cclk() / 1000;
 112 }
 113
 114 #ifdef CONFIG_BF60x
 115 unsigned long cpu_set_cclk(int cpu, unsigned long new)
 116 {
 117         struct clk *clk;
 118         int ret;
 119
 120         clk = clk_get(NULL, "CCLK");
 121         if (IS_ERR(clk))
 122                 return -ENODEV;
 123
 124         ret = clk_set_rate(clk, new);
 125         clk_put(clk);
 126         return ret;
 127 }
 128 #endif
 129
 130 static int bfin_target(struct cpufreq_policy *policy, unsigned int index)
 131 {
 132 #ifndef CONFIG_BF60x
 133         unsigned int plldiv;
 134 #endif
 135         static unsigned long lpj_ref;
 136         static unsigned int  lpj_ref_freq;
 137         unsigned int old_freq, new_freq;
 138         int ret = 0;
 139
 140 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
 141         cycles_t cycles;
 142 #endif
 143
 144         old_freq = bfin_getfreq_khz(0);
 145         new_freq = bfin_freq_table[index].frequency;
 146
 147 #ifndef CONFIG_BF60x
 148         plldiv = (bfin_read_PLL_DIV() & SSEL) | dpm_state_table[index].csel;
 149         bfin_write_PLL_DIV(plldiv);
 150 #else
 151         ret = cpu_set_cclk(policy->cpu, new_freq * 1000);
 152         if (ret != 0) {
 153                 WARN_ONCE(ret, "cpufreq set freq failed %d\n", ret);
 154                 return ret;
 155         }
 156 #endif
 157         on_each_cpu(bfin_adjust_core_timer, &index, 1);
 158 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
 159         cycles = get_cycles();
 160         SSYNC();
 161         cycles += 10; /* ~10 cycles we lose after get_cycles() */
 162         __bfin_cycles_off += (cycles << __bfin_cycles_mod) - (cycles << index);
 163         __bfin_cycles_mod = index;
 164 #endif
 165         if (!lpj_ref_freq) {
 166                 lpj_ref = loops_per_jiffy;
 167                 lpj_ref_freq = old_freq;
 168         }
 169         if (new_freq != old_freq) {
 170                 loops_per_jiffy = cpufreq_scale(lpj_ref,
 171                                 lpj_ref_freq, new_freq);
 172         }
 173
 174         return ret;
 175 }
 176
 177 static int __bfin_cpu_init(struct cpufreq_policy *policy)
 178 {
 179
 180         unsigned long cclk, sclk;
 181
 182         cclk = get_cclk() / 1000;
 183         sclk = get_sclk() / 1000;
 184
 185         if (policy->cpu == CPUFREQ_CPU)
 186                 bfin_init_tables(cclk, sclk);
 187
 188         policy->cpuinfo.transition_latency = 50000; /* 50us assumed */
 189
 190         return cpufreq_table_validate_and_show(policy, bfin_freq_table);
 191 }
 192
 193 static struct cpufreq_driver bfin_driver = {
 194         .verify = cpufreq_generic_frequency_table_verify,
 195         .target_index = bfin_target,
 196         .get = bfin_getfreq_khz,
 197         .init = __bfin_cpu_init,
 198         .exit = cpufreq_generic_exit,
 199         .name = "bfin cpufreq",
 200         .attr = cpufreq_generic_attr,
 201 };
 202
 203 static int __init bfin_cpu_init(void)
 204 {
 205         return cpufreq_register_driver(&bfin_driver);
 206 }
 207
 208 static void __exit bfin_cpu_exit(void)
 209 {
 210         cpufreq_unregister_driver(&bfin_driver);
 211 }
 212
 213 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 214 MODULE_DESCRIPTION("cpufreq driver for Blackfin");
 215 MODULE_LICENSE("GPL");
 216
 217 module_init(bfin_cpu_init);
 218 module_exit(bfin_cpu_exit);