drivers/cpufreq/powernow-k6.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *  This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
0004  *  (C) 2000-2003  Dave Jones, Arjan van de Ven, Janne Pänkälä,
0005  *                 Dominik Brodowski.
0006  *
0007  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
0008  */
0009
0010 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0011
0012 #include <linux/kernel.h>
0013 #include <linux/module.h>
0014 #include <linux/init.h>
0015 #include <linux/cpufreq.h>
0016 #include <linux/ioport.h>
0017 #include <linux/timex.h>
0018 #include <linux/io.h>
0019
0020 #include <asm/cpu_device_id.h>
0021 #include <asm/msr.h>
0022
0023 #define POWERNOW_IOPORT 0xfff0          /* it doesn't matter where, as long
0024                        as it is unused */
0025
0026 static unsigned int                     busfreq;   /* FSB, in 10 kHz */
0027 static unsigned int                     max_multiplier;
0028
0029 static unsigned int         param_busfreq = 0;
0030 static unsigned int         param_max_multiplier = 0;
0031
0032 module_param_named(max_multiplier, param_max_multiplier, uint, S_IRUGO);
0033 MODULE_PARM_DESC(max_multiplier, "Maximum multiplier (allowed values: 20 30 35 40 45 50 55 60)");
0034
0035 module_param_named(bus_frequency, param_busfreq, uint, S_IRUGO);
0036 MODULE_PARM_DESC(bus_frequency, "Bus frequency in kHz");
0037
0038 /* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
0039 static struct cpufreq_frequency_table clock_ratio[] = {
0040     {0, 60,  /* 110 -> 6.0x */ 0},
0041     {0, 55,  /* 011 -> 5.5x */ 0},
0042     {0, 50,  /* 001 -> 5.0x */ 0},
0043     {0, 45,  /* 000 -> 4.5x */ 0},
0044     {0, 40,  /* 010 -> 4.0x */ 0},
0045     {0, 35,  /* 111 -> 3.5x */ 0},
0046     {0, 30,  /* 101 -> 3.0x */ 0},
0047     {0, 20,  /* 100 -> 2.0x */ 0},
0048     {0, 0, CPUFREQ_TABLE_END}
0049 };
0050
0051 static const u8 index_to_register[8] = { 6, 3, 1, 0, 2, 7, 5, 4 };
0052 static const u8 register_to_index[8] = { 3, 2, 4, 1, 7, 6, 0, 5 };
0053
0054 static const struct {
0055     unsigned freq;
0056     unsigned mult;
0057 } usual_frequency_table[] = {
0058     { 350000, 35 }, // 100   * 3.5
0059     { 400000, 40 }, // 100   * 4
0060     { 450000, 45 }, // 100   * 4.5
0061     { 475000, 50 }, //  95   * 5
0062     { 500000, 50 }, // 100   * 5
0063     { 506250, 45 }, // 112.5 * 4.5
0064     { 533500, 55 }, //  97   * 5.5
0065     { 550000, 55 }, // 100   * 5.5
0066     { 562500, 50 }, // 112.5 * 5
0067     { 570000, 60 }, //  95   * 6
0068     { 600000, 60 }, // 100   * 6
0069     { 618750, 55 }, // 112.5 * 5.5
0070     { 660000, 55 }, // 120   * 5.5
0071     { 675000, 60 }, // 112.5 * 6
0072     { 720000, 60 }, // 120   * 6
0073 };
0074
0075 #define FREQ_RANGE      3000
0076
0077 /**
0078  * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
0079  *
0080  * Returns the current setting of the frequency multiplier. Core clock
0081  * speed is frequency of the Front-Side Bus multiplied with this value.
0082  */
0083 static int powernow_k6_get_cpu_multiplier(void)
0084 {
0085     unsigned long invalue = 0;
0086     u32 msrval;
0087
0088     local_irq_disable();
0089
0090     msrval = POWERNOW_IOPORT + 0x1;
0091     wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
0092     invalue = inl(POWERNOW_IOPORT + 0x8);
0093     msrval = POWERNOW_IOPORT + 0x0;
0094     wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
0095
0096     local_irq_enable();
0097
0098     return clock_ratio[register_to_index[(invalue >> 5)&7]].driver_data;
0099 }
0100
0101 static void powernow_k6_set_cpu_multiplier(unsigned int best_i)
0102 {
0103     unsigned long outvalue, invalue;
0104     unsigned long msrval;
0105     unsigned long cr0;
0106
0107     /* we now need to transform best_i to the BVC format, see AMD#23446 */
0108
0109     /*
0110      * The processor doesn't respond to inquiry cycles while changing the
0111      * frequency, so we must disable cache.
0112      */
0113     local_irq_disable();
0114     cr0 = read_cr0();
0115     write_cr0(cr0 | X86_CR0_CD);
0116     wbinvd();
0117
0118     outvalue = (1<<12) | (1<<10) | (1<<9) | (index_to_register[best_i]<<5);
0119
0120     msrval = POWERNOW_IOPORT + 0x1;
0121     wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
0122     invalue = inl(POWERNOW_IOPORT + 0x8);
0123     invalue = invalue & 0x1f;
0124     outvalue = outvalue | invalue;
0125     outl(outvalue, (POWERNOW_IOPORT + 0x8));
0126     msrval = POWERNOW_IOPORT + 0x0;
0127     wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
0128
0129     write_cr0(cr0);
0130     local_irq_enable();
0131 }
0132
0133 /**
0134  * powernow_k6_target - set the PowerNow! multiplier
0135  * @best_i: clock_ratio[best_i] is the target multiplier
0136  *
0137  *   Tries to change the PowerNow! multiplier
0138  */
0139 static int powernow_k6_target(struct cpufreq_policy *policy,
0140         unsigned int best_i)
0141 {
0142
0143     if (clock_ratio[best_i].driver_data > max_multiplier) {
0144         pr_err("invalid target frequency\n");
0145         return -EINVAL;
0146     }
0147
0148     powernow_k6_set_cpu_multiplier(best_i);
0149
0150     return 0;
0151 }
0152
0153 static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
0154 {
0155     struct cpufreq_frequency_table *pos;
0156     unsigned int i, f;
0157     unsigned khz;
0158
0159     if (policy->cpu != 0)
0160         return -ENODEV;
0161
0162     max_multiplier = 0;
0163     khz = cpu_khz;
0164     for (i = 0; i < ARRAY_SIZE(usual_frequency_table); i++) {
0165         if (khz >= usual_frequency_table[i].freq - FREQ_RANGE &&
0166             khz <= usual_frequency_table[i].freq + FREQ_RANGE) {
0167             khz = usual_frequency_table[i].freq;
0168             max_multiplier = usual_frequency_table[i].mult;
0169             break;
0170         }
0171     }
0172     if (param_max_multiplier) {
0173         cpufreq_for_each_entry(pos, clock_ratio)
0174             if (pos->driver_data == param_max_multiplier) {
0175                 max_multiplier = param_max_multiplier;
0176                 goto have_max_multiplier;
0177             }
0178         pr_err("invalid max_multiplier parameter, valid parameters 20, 30, 35, 40, 45, 50, 55, 60\n");
0179         return -EINVAL;
0180     }
0181
0182     if (!max_multiplier) {
0183         pr_warn("unknown frequency %u, cannot determine current multiplier\n",
0184             khz);
0185         pr_warn("use module parameters max_multiplier and bus_frequency\n");
0186         return -EOPNOTSUPP;
0187     }
0188
0189 have_max_multiplier:
0190     param_max_multiplier = max_multiplier;
0191
0192     if (param_busfreq) {
0193         if (param_busfreq >= 50000 && param_busfreq <= 150000) {
0194             busfreq = param_busfreq / 10;
0195             goto have_busfreq;
0196         }
0197         pr_err("invalid bus_frequency parameter, allowed range 50000 - 150000 kHz\n");
0198         return -EINVAL;
0199     }
0200
0201     busfreq = khz / max_multiplier;
0202 have_busfreq:
0203     param_busfreq = busfreq * 10;
0204
0205     /* table init */
0206     cpufreq_for_each_entry(pos, clock_ratio) {
0207         f = pos->driver_data;
0208         if (f > max_multiplier)
0209             pos->frequency = CPUFREQ_ENTRY_INVALID;
0210         else
0211             pos->frequency = busfreq * f;
0212     }
0213
0214     /* cpuinfo and default policy values */
0215     policy->cpuinfo.transition_latency = 500000;
0216     policy->freq_table = clock_ratio;
0217
0218     return 0;
0219 }
0220
0221
0222 static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
0223 {
0224     unsigned int i;
0225
0226     for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
0227         if (clock_ratio[i].driver_data == max_multiplier) {
0228             struct cpufreq_freqs freqs;
0229
0230             freqs.old = policy->cur;
0231             freqs.new = clock_ratio[i].frequency;
0232             freqs.flags = 0;
0233
0234             cpufreq_freq_transition_begin(policy, &freqs);
0235             powernow_k6_target(policy, i);
0236             cpufreq_freq_transition_end(policy, &freqs, 0);
0237             break;
0238         }
0239     }
0240     return 0;
0241 }
0242
0243 static unsigned int powernow_k6_get(unsigned int cpu)
0244 {
0245     unsigned int ret;
0246     ret = (busfreq * powernow_k6_get_cpu_multiplier());
0247     return ret;
0248 }
0249
0250 static struct cpufreq_driver powernow_k6_driver = {
0251     .verify     = cpufreq_generic_frequency_table_verify,
0252     .target_index   = powernow_k6_target,
0253     .init       = powernow_k6_cpu_init,
0254     .exit       = powernow_k6_cpu_exit,
0255     .get        = powernow_k6_get,
0256     .name       = "powernow-k6",
0257     .attr       = cpufreq_generic_attr,
0258 };
0259
0260 static const struct x86_cpu_id powernow_k6_ids[] = {
0261     X86_MATCH_VENDOR_FAM_MODEL(AMD, 5, 12, NULL),
0262     X86_MATCH_VENDOR_FAM_MODEL(AMD, 5, 13, NULL),
0263     {}
0264 };
0265 MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);
0266
0267 /**
0268  * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
0269  *
0270  *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
0271  * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
0272  * on success.
0273  */
0274 static int __init powernow_k6_init(void)
0275 {
0276     if (!x86_match_cpu(powernow_k6_ids))
0277         return -ENODEV;
0278
0279     if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
0280         pr_info("PowerNow IOPORT region already used\n");
0281         return -EIO;
0282     }
0283
0284     if (cpufreq_register_driver(&powernow_k6_driver)) {
0285         release_region(POWERNOW_IOPORT, 16);
0286         return -EINVAL;
0287     }
0288
0289     return 0;
0290 }
0291
0292
0293 /**
0294  * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
0295  *
0296  *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
0297  */
0298 static void __exit powernow_k6_exit(void)
0299 {
0300     cpufreq_unregister_driver(&powernow_k6_driver);
0301     release_region(POWERNOW_IOPORT, 16);
0302 }
0303
0304
0305 MODULE_AUTHOR("Arjan van de Ven, Dave Jones, "
0306         "Dominik Brodowski <linux@brodo.de>");
0307 MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
0308 MODULE_LICENSE("GPL");
0309
0310 module_init(powernow_k6_init);
0311 module_exit(powernow_k6_exit);