drivers/cpufreq/sc520_freq.c

   1 /*
   2  *      sc520_freq.c: cpufreq driver for the AMD Elan sc520
   3  *
   4  *      Copyright (C) 2005 Sean Young <sean@mess.org>
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  *
  11  *      Based on elanfreq.c
  12  *
  13  *      2005-03-30: - initial revision
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/init.h>
  19
  20 #include <linux/delay.h>
  21 #include <linux/cpufreq.h>
  22 #include <linux/timex.h>
  23 #include <linux/io.h>
  24
  25 #include <asm/cpu_device_id.h>
  26 #include <asm/msr.h>
  27
  28 #define MMCR_BASE       0xfffef000      /* The default base address */
  29 #define OFFS_CPUCTL     0x2   /* CPU Control Register */
  30
  31 static __u8 __iomem *cpuctl;
  32
  33 #define PFX "sc520_freq: "
  34
  35 static struct cpufreq_frequency_table sc520_freq_table[] = {
  36         {0x01,  100000},
  37         {0x02,  133000},
  38         {0,     CPUFREQ_TABLE_END},
  39 };
  40
  41 static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu)
  42 {
  43         u8 clockspeed_reg = *cpuctl;
  44
  45         switch (clockspeed_reg & 0x03) {
  46         default:
  47                 printk(KERN_ERR PFX "error: cpuctl register has unexpected "
  48                                 "value %02x\n", clockspeed_reg);
  49         case 0x01:
  50                 return 100000;
  51         case 0x02:
  52                 return 133000;
  53         }
  54 }
  55
  56 static void sc520_freq_set_cpu_state(struct cpufreq_policy *policy,
  57                 unsigned int state)
  58 {
  59
  60         struct cpufreq_freqs    freqs;
  61         u8 clockspeed_reg;
  62
  63         freqs.old = sc520_freq_get_cpu_frequency(0);
  64         freqs.new = sc520_freq_table[state].frequency;
  65
  66         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  67
  68         pr_debug("attempting to set frequency to %i kHz\n",
  69                         sc520_freq_table[state].frequency);
  70
  71         local_irq_disable();
  72
  73         clockspeed_reg = *cpuctl & ~0x03;
  74         *cpuctl = clockspeed_reg | sc520_freq_table[state].driver_data;
  75
  76         local_irq_enable();
  77
  78         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  79 };
  80
  81 static int sc520_freq_verify(struct cpufreq_policy *policy)
  82 {
  83         return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]);
  84 }
  85
  86 static int sc520_freq_target(struct cpufreq_policy *policy,
  87                             unsigned int target_freq,
  88                             unsigned int relation)
  89 {
  90         unsigned int newstate = 0;
  91
  92         if (cpufreq_frequency_table_target(policy, sc520_freq_table,
  93                                 target_freq, relation, &newstate))
  94                 return -EINVAL;
  95
  96         sc520_freq_set_cpu_state(policy, newstate);
  97
  98         return 0;
  99 }
 100
 101
 102 /*
 103  *      Module init and exit code
 104  */
 105
 106 static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
 107 {
 108         struct cpuinfo_x86 *c = &cpu_data(0);
 109         int result;
 110
 111         /* capability check */
 112         if (c->x86_vendor != X86_VENDOR_AMD ||
 113             c->x86 != 4 || c->x86_model != 9)
 114                 return -ENODEV;
 115
 116         /* cpuinfo and default policy values */
 117         policy->cpuinfo.transition_latency = 1000000; /* 1ms */
 118         policy->cur = sc520_freq_get_cpu_frequency(0);
 119
 120         result = cpufreq_frequency_table_cpuinfo(policy, sc520_freq_table);
 121         if (result)
 122                 return result;
 123
 124         cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu);
 125
 126         return 0;
 127 }
 128
 129
 130 static int sc520_freq_cpu_exit(struct cpufreq_policy *policy)
 131 {
 132         cpufreq_frequency_table_put_attr(policy->cpu);
 133         return 0;
 134 }
 135
 136
 137 static struct freq_attr *sc520_freq_attr[] = {
 138         &cpufreq_freq_attr_scaling_available_freqs,
 139         NULL,
 140 };
 141
 142
 143 static struct cpufreq_driver sc520_freq_driver = {
 144         .get    = sc520_freq_get_cpu_frequency,
 145         .verify = sc520_freq_verify,
 146         .target = sc520_freq_target,
 147         .init   = sc520_freq_cpu_init,
 148         .exit   = sc520_freq_cpu_exit,
 149         .name   = "sc520_freq",
 150         .attr   = sc520_freq_attr,
 151 };
 152
 153 static const struct x86_cpu_id sc520_ids[] = {
 154         { X86_VENDOR_AMD, 4, 9 },
 155         {}
 156 };
 157 MODULE_DEVICE_TABLE(x86cpu, sc520_ids);
 158
 159 static int __init sc520_freq_init(void)
 160 {
 161         int err;
 162
 163         if (!x86_match_cpu(sc520_ids))
 164                 return -ENODEV;
 165
 166         cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
 167         if (!cpuctl) {
 168                 printk(KERN_ERR "sc520_freq: error: failed to remap memory\n");
 169                 return -ENOMEM;
 170         }
 171
 172         err = cpufreq_register_driver(&sc520_freq_driver);
 173         if (err)
 174                 iounmap(cpuctl);
 175
 176         return err;
 177 }
 178
 179
 180 static void __exit sc520_freq_exit(void)
 181 {
 182         cpufreq_unregister_driver(&sc520_freq_driver);
 183         iounmap(cpuctl);
 184 }
 185
 186
 187 MODULE_LICENSE("GPL");
 188 MODULE_AUTHOR("Sean Young <sean@mess.org>");
 189 MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU");
 190
 191 module_init(sc520_freq_init);
 192 module_exit(sc520_freq_exit);
 193