drivers/cpufreq/powernow-k6.c

   1 /*
   2  *  This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
   3  *  (C) 2000-2003  Dave Jones, Arjan van de Ven, Janne Pänkälä,
   4  *                 Dominik Brodowski.
   5  *
   6  *  Licensed under the terms of the GNU GPL License version 2.
   7  *
   8  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/cpufreq.h>
  15 #include <linux/ioport.h>
  16 #include <linux/timex.h>
  17 #include <linux/io.h>
  18
  19 #include <asm/cpu_device_id.h>
  20 #include <asm/msr.h>
  21
  22 #define POWERNOW_IOPORT 0xfff0          /* it doesn't matter where, as long
  23                                            as it is unused */
  24
  25 #define PFX "powernow-k6: "
  26 static unsigned int                     busfreq;   /* FSB, in 10 kHz */
  27 static unsigned int                     max_multiplier;
  28
  29
  30 /* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
  31 static struct cpufreq_frequency_table clock_ratio[] = {
  32         {45,  /* 000 -> 4.5x */ 0},
  33         {50,  /* 001 -> 5.0x */ 0},
  34         {40,  /* 010 -> 4.0x */ 0},
  35         {55,  /* 011 -> 5.5x */ 0},
  36         {20,  /* 100 -> 2.0x */ 0},
  37         {30,  /* 101 -> 3.0x */ 0},
  38         {60,  /* 110 -> 6.0x */ 0},
  39         {35,  /* 111 -> 3.5x */ 0},
  40         {0, CPUFREQ_TABLE_END}
  41 };
  42
  43
  44 /**
  45  * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
  46  *
  47  *   Returns the current setting of the frequency multiplier. Core clock
  48  * speed is frequency of the Front-Side Bus multiplied with this value.
  49  */
  50 static int powernow_k6_get_cpu_multiplier(void)
  51 {
  52         u64 invalue = 0;
  53         u32 msrval;
  54
  55         msrval = POWERNOW_IOPORT + 0x1;
  56         wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  57         invalue = inl(POWERNOW_IOPORT + 0x8);
  58         msrval = POWERNOW_IOPORT + 0x0;
  59         wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
  60
  61         return clock_ratio[(invalue >> 5)&7].driver_data;
  62 }
  63
  64
  65 /**
  66  * powernow_k6_target - set the PowerNow! multiplier
  67  * @best_i: clock_ratio[best_i] is the target multiplier
  68  *
  69  *   Tries to change the PowerNow! multiplier
  70  */
  71 static int powernow_k6_target(struct cpufreq_policy *policy,
  72                 unsigned int best_i)
  73 {
  74         unsigned long outvalue = 0, invalue = 0;
  75         unsigned long msrval;
  76         struct cpufreq_freqs freqs;
  77
  78         if (clock_ratio[best_i].driver_data > max_multiplier) {
  79                 printk(KERN_ERR PFX "invalid target frequency\n");
  80                 return -EINVAL;
  81         }
  82
  83         freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
  84         freqs.new = busfreq * clock_ratio[best_i].driver_data;
  85
  86         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  87
  88         /* we now need to transform best_i to the BVC format, see AMD#23446 */
  89
  90         outvalue = (1<<12) | (1<<10) | (1<<9) | (best_i<<5);
  91
  92         msrval = POWERNOW_IOPORT + 0x1;
  93         wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  94         invalue = inl(POWERNOW_IOPORT + 0x8);
  95         invalue = invalue & 0xf;
  96         outvalue = outvalue | invalue;
  97         outl(outvalue , (POWERNOW_IOPORT + 0x8));
  98         msrval = POWERNOW_IOPORT + 0x0;
  99         wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
 100
 101         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 102
 103         return 0;
 104 }
 105
 106
 107 static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
 108 {
 109         unsigned int i, f;
 110
 111         if (policy->cpu != 0)
 112                 return -ENODEV;
 113
 114         /* get frequencies */
 115         max_multiplier = powernow_k6_get_cpu_multiplier();
 116         busfreq = cpu_khz / max_multiplier;
 117
 118         /* table init */
 119         for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
 120                 f = clock_ratio[i].driver_data;
 121                 if (f > max_multiplier)
 122                         clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
 123                 else
 124                         clock_ratio[i].frequency = busfreq * f;
 125         }
 126
 127         /* cpuinfo and default policy values */
 128         policy->cpuinfo.transition_latency = 200000;
 129
 130         return cpufreq_table_validate_and_show(policy, clock_ratio);
 131 }
 132
 133
 134 static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
 135 {
 136         unsigned int i;
 137         for (i = 0; i < 8; i++) {
 138                 if (i == max_multiplier)
 139                         powernow_k6_target(policy, i);
 140         }
 141         cpufreq_frequency_table_put_attr(policy->cpu);
 142         return 0;
 143 }
 144
 145 static unsigned int powernow_k6_get(unsigned int cpu)
 146 {
 147         unsigned int ret;
 148         ret = (busfreq * powernow_k6_get_cpu_multiplier());
 149         return ret;
 150 }
 151
 152 static struct cpufreq_driver powernow_k6_driver = {
 153         .verify         = cpufreq_generic_frequency_table_verify,
 154         .target_index   = powernow_k6_target,
 155         .init           = powernow_k6_cpu_init,
 156         .exit           = powernow_k6_cpu_exit,
 157         .get            = powernow_k6_get,
 158         .name           = "powernow-k6",
 159         .attr           = cpufreq_generic_attr,
 160 };
 161
 162 static const struct x86_cpu_id powernow_k6_ids[] = {
 163         { X86_VENDOR_AMD, 5, 12 },
 164         { X86_VENDOR_AMD, 5, 13 },
 165         {}
 166 };
 167 MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);
 168
 169 /**
 170  * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
 171  *
 172  *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
 173  * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
 174  * on success.
 175  */
 176 static int __init powernow_k6_init(void)
 177 {
 178         if (!x86_match_cpu(powernow_k6_ids))
 179                 return -ENODEV;
 180
 181         if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
 182                 printk(KERN_INFO PFX "PowerNow IOPORT region already used.\n");
 183                 return -EIO;
 184         }
 185
 186         if (cpufreq_register_driver(&powernow_k6_driver)) {
 187                 release_region(POWERNOW_IOPORT, 16);
 188                 return -EINVAL;
 189         }
 190
 191         return 0;
 192 }
 193
 194
 195 /**
 196  * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
 197  *
 198  *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
 199  */
 200 static void __exit powernow_k6_exit(void)
 201 {
 202         cpufreq_unregister_driver(&powernow_k6_driver);
 203         release_region(POWERNOW_IOPORT, 16);
 204 }
 205
 206
 207 MODULE_AUTHOR("Arjan van de Ven, Dave Jones <davej@redhat.com>, "
 208                 "Dominik Brodowski <linux@brodo.de>");
 209 MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
 210 MODULE_LICENSE("GPL");
 211
 212 module_init(powernow_k6_init);
 213 module_exit(powernow_k6_exit);