linux/drivers/cpufreq/powernow-k6.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
   4 *  (C) 2000-2003  Dave Jones, Arjan van de Ven, Janne P\xC3\xA4nk\xC3\xA4l\xC3\xA4,
   5 *                 Dominik Brodowski.
   6 *
   7 *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   8 */
   9
  10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12#include <linux/kernel.h>
  13#include <linux/module.h>
  14#include <linux/init.h>
  15#include <linux/cpufreq.h>
  16#include <linux/ioport.h>
  17#include <linux/timex.h>
  18#include <linux/io.h>
  19
  20#include <asm/cpu_device_id.h>
  21#include <asm/msr.h>
  22
  23#define POWERNOW_IOPORT 0xfff0          /* it doesn't matter where, as long
  24                                           as it is unused */
  25
  26static unsigned int                     busfreq;   /* FSB, in 10 kHz */
  27static unsigned int                     max_multiplier;
  28
  29static unsigned int                     param_busfreq = 0;
  30static unsigned int                     param_max_multiplier = 0;
  31
  32module_param_named(max_multiplier, param_max_multiplier, uint, S_IRUGO);
  33MODULE_PARM_DESC(max_multiplier, "Maximum multiplier (allowed values: 20 30 35 40 45 50 55 60)");
  34
  35module_param_named(bus_frequency, param_busfreq, uint, S_IRUGO);
  36MODULE_PARM_DESC(bus_frequency, "Bus frequency in kHz");
  37
  38/* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
  39static struct cpufreq_frequency_table clock_ratio[] = {
  40        {0, 60,  /* 110 -> 6.0x */ 0},
  41        {0, 55,  /* 011 -> 5.5x */ 0},
  42        {0, 50,  /* 001 -> 5.0x */ 0},
  43        {0, 45,  /* 000 -> 4.5x */ 0},
  44        {0, 40,  /* 010 -> 4.0x */ 0},
  45        {0, 35,  /* 111 -> 3.5x */ 0},
  46        {0, 30,  /* 101 -> 3.0x */ 0},
  47        {0, 20,  /* 100 -> 2.0x */ 0},
  48        {0, 0, CPUFREQ_TABLE_END}
  49};
  50
  51static const u8 index_to_register[8] = { 6, 3, 1, 0, 2, 7, 5, 4 };
  52static const u8 register_to_index[8] = { 3, 2, 4, 1, 7, 6, 0, 5 };
  53
  54static const struct {
  55        unsigned freq;
  56        unsigned mult;
  57} usual_frequency_table[] = {
  58        { 350000, 35 }, // 100   * 3.5
  59        { 400000, 40 }, // 100   * 4
  60        { 450000, 45 }, // 100   * 4.5
  61        { 475000, 50 }, //  95   * 5
  62        { 500000, 50 }, // 100   * 5
  63        { 506250, 45 }, // 112.5 * 4.5
  64        { 533500, 55 }, //  97   * 5.5
  65        { 550000, 55 }, // 100   * 5.5
  66        { 562500, 50 }, // 112.5 * 5
  67        { 570000, 60 }, //  95   * 6
  68        { 600000, 60 }, // 100   * 6
  69        { 618750, 55 }, // 112.5 * 5.5
  70        { 660000, 55 }, // 120   * 5.5
  71        { 675000, 60 }, // 112.5 * 6
  72        { 720000, 60 }, // 120   * 6
  73};
  74
  75#define FREQ_RANGE              3000
  76
  77/**
  78 * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
  79 *
  80 * Returns the current setting of the frequency multiplier. Core clock
  81 * speed is frequency of the Front-Side Bus multiplied with this value.
  82 */
  83static int powernow_k6_get_cpu_multiplier(void)
  84{
  85        unsigned long invalue = 0;
  86        u32 msrval;
  87
  88        local_irq_disable();
  89
  90        msrval = POWERNOW_IOPORT + 0x1;
  91        wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  92        invalue = inl(POWERNOW_IOPORT + 0x8);
  93        msrval = POWERNOW_IOPORT + 0x0;
  94        wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
  95
  96        local_irq_enable();
  97
  98        return clock_ratio[register_to_index[(invalue >> 5)&7]].driver_data;
  99}
 100
 101static void powernow_k6_set_cpu_multiplier(unsigned int best_i)
 102{
 103        unsigned long outvalue, invalue;
 104        unsigned long msrval;
 105        unsigned long cr0;
 106
 107        /* we now need to transform best_i to the BVC format, see AMD#23446 */
 108
 109        /*
 110         * The processor doesn't respond to inquiry cycles while changing the
 111         * frequency, so we must disable cache.
 112         */
 113        local_irq_disable();
 114        cr0 = read_cr0();
 115        write_cr0(cr0 | X86_CR0_CD);
 116        wbinvd();
 117
 118        outvalue = (1<<12) | (1<<10) | (1<<9) | (index_to_register[best_i]<<5);
 119
 120        msrval = POWERNOW_IOPORT + 0x1;
 121        wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
 122        invalue = inl(POWERNOW_IOPORT + 0x8);
 123        invalue = invalue & 0x1f;
 124        outvalue = outvalue | invalue;
 125        outl(outvalue, (POWERNOW_IOPORT + 0x8));
 126        msrval = POWERNOW_IOPORT + 0x0;
 127        wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
 128
 129        write_cr0(cr0);
 130        local_irq_enable();
 131}
 132
 133/**
 134 * powernow_k6_target - set the PowerNow! multiplier
 135 * @best_i: clock_ratio[best_i] is the target multiplier
 136 *
 137 *   Tries to change the PowerNow! multiplier
 138 */
 139static int powernow_k6_target(struct cpufreq_policy *policy,
 140                unsigned int best_i)
 141{
 142
 143        if (clock_ratio[best_i].driver_data > max_multiplier) {
 144                pr_err("invalid target frequency\n");
 145                return -EINVAL;
 146        }
 147
 148        powernow_k6_set_cpu_multiplier(best_i);
 149
 150        return 0;
 151}
 152
 153static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
 154{
 155        struct cpufreq_frequency_table *pos;
 156        unsigned int i, f;
 157        unsigned khz;
 158
 159        if (policy->cpu != 0)
 160                return -ENODEV;
 161
 162        max_multiplier = 0;
 163        khz = cpu_khz;
 164        for (i = 0; i < ARRAY_SIZE(usual_frequency_table); i++) {
 165                if (khz >= usual_frequency_table[i].freq - FREQ_RANGE &&
 166                    khz <= usual_frequency_table[i].freq + FREQ_RANGE) {
 167                        khz = usual_frequency_table[i].freq;
 168                        max_multiplier = usual_frequency_table[i].mult;
 169                        break;
 170                }
 171        }
 172        if (param_max_multiplier) {
 173                cpufreq_for_each_entry(pos, clock_ratio)
 174                        if (pos->driver_data == param_max_multiplier) {
 175                                max_multiplier = param_max_multiplier;
 176                                goto have_max_multiplier;
 177                        }
 178                pr_err("invalid max_multiplier parameter, valid parameters 20, 30, 35, 40, 45, 50, 55, 60\n");
 179                return -EINVAL;
 180        }
 181
 182        if (!max_multiplier) {
 183                pr_warn("unknown frequency %u, cannot determine current multiplier\n",
 184                        khz);
 185                pr_warn("use module parameters max_multiplier and bus_frequency\n");
 186                return -EOPNOTSUPP;
 187        }
 188
 189have_max_multiplier:
 190        param_max_multiplier = max_multiplier;
 191
 192        if (param_busfreq) {
 193                if (param_busfreq >= 50000 && param_busfreq <= 150000) {
 194                        busfreq = param_busfreq / 10;
 195                        goto have_busfreq;
 196                }
 197                pr_err("invalid bus_frequency parameter, allowed range 50000 - 150000 kHz\n");
 198                return -EINVAL;
 199        }
 200
 201        busfreq = khz / max_multiplier;
 202have_busfreq:
 203        param_busfreq = busfreq * 10;
 204
 205        /* table init */
 206        cpufreq_for_each_entry(pos, clock_ratio) {
 207                f = pos->driver_data;
 208                if (f > max_multiplier)
 209                        pos->frequency = CPUFREQ_ENTRY_INVALID;
 210                else
 211                        pos->frequency = busfreq * f;
 212        }
 213
 214        /* cpuinfo and default policy values */
 215        policy->cpuinfo.transition_latency = 500000;
 216        policy->freq_table = clock_ratio;
 217
 218        return 0;
 219}
 220
 221
 222static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
 223{
 224        unsigned int i;
 225
 226        for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
 227                if (clock_ratio[i].driver_data == max_multiplier) {
 228                        struct cpufreq_freqs freqs;
 229
 230                        freqs.old = policy->cur;
 231                        freqs.new = clock_ratio[i].frequency;
 232                        freqs.flags = 0;
 233
 234                        cpufreq_freq_transition_begin(policy, &freqs);
 235                        powernow_k6_target(policy, i);
 236                        cpufreq_freq_transition_end(policy, &freqs, 0);
 237                        break;
 238                }
 239        }
 240        return 0;
 241}
 242
 243static unsigned int powernow_k6_get(unsigned int cpu)
 244{
 245        unsigned int ret;
 246        ret = (busfreq * powernow_k6_get_cpu_multiplier());
 247        return ret;
 248}
 249
 250static struct cpufreq_driver powernow_k6_driver = {
 251        .verify         = cpufreq_generic_frequency_table_verify,
 252        .target_index   = powernow_k6_target,
 253        .init           = powernow_k6_cpu_init,
 254        .exit           = powernow_k6_cpu_exit,
 255        .get            = powernow_k6_get,
 256        .name           = "powernow-k6",
 257        .attr           = cpufreq_generic_attr,
 258};
 259
 260static const struct x86_cpu_id powernow_k6_ids[] = {
 261        X86_MATCH_VENDOR_FAM_MODEL(AMD, 5, 12, NULL),
 262        X86_MATCH_VENDOR_FAM_MODEL(AMD, 5, 13, NULL),
 263        {}
 264};
 265MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);
 266
 267/**
 268 * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
 269 *
 270 *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
 271 * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
 272 * on success.
 273 */
 274static int __init powernow_k6_init(void)
 275{
 276        if (!x86_match_cpu(powernow_k6_ids))
 277                return -ENODEV;
 278
 279        if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
 280                pr_info("PowerNow IOPORT region already used\n");
 281                return -EIO;
 282        }
 283
 284        if (cpufreq_register_driver(&powernow_k6_driver)) {
 285                release_region(POWERNOW_IOPORT, 16);
 286                return -EINVAL;
 287        }
 288
 289        return 0;
 290}
 291
 292
 293/**
 294 * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
 295 *
 296 *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
 297 */
 298static void __exit powernow_k6_exit(void)
 299{
 300        cpufreq_unregister_driver(&powernow_k6_driver);
 301        release_region(POWERNOW_IOPORT, 16);
 302}
 303
 304
 305MODULE_AUTHOR("Arjan van de Ven, Dave Jones, "
 306                "Dominik Brodowski <linux@brodo.de>");
 307MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
 308MODULE_LICENSE("GPL");
 309
 310module_init(powernow_k6_init);
 311module_exit(powernow_k6_exit);
 312