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 Pänkälä,
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
26 static unsigned int busfreq; /* FSB, in 10 kHz */
27 static unsigned int max_multiplier;
28
29 static unsigned int param_busfreq = 0;
30 static unsigned int param_max_multiplier = 0;
31
32 module_param_named(max_multiplier, param_max_multiplier, uint, S_IRUGO);
33 MODULE_PARM_DESC(max_multiplier, "Maximum multiplier (allowed values: 20 30 35 40 45 50 55 60)");
34
35 module_param_named(bus_frequency, param_busfreq, uint, S_IRUGO);
36 MODULE_PARM_DESC(bus_frequency, "Bus frequency in kHz");
37
38 /* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
39 static 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
51 static const u8 index_to_register[8] = { 6, 3, 1, 0, 2, 7, 5, 4 };
52 static const u8 register_to_index[8] = { 3, 2, 4, 1, 7, 6, 0, 5 };
53
54 static 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 */
powernow_k6_get_cpu_multiplier(void)83 static 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
powernow_k6_set_cpu_multiplier(unsigned int best_i)101 static 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 */
powernow_k6_target(struct cpufreq_policy * policy,unsigned int best_i)139 static 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
powernow_k6_cpu_init(struct cpufreq_policy * policy)153 static 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
189 have_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;
202 have_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
powernow_k6_cpu_exit(struct cpufreq_policy * policy)222 static 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
powernow_k6_get(unsigned int cpu)243 static 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
250 static 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
260 static 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 };
265 MODULE_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 */
powernow_k6_init(void)274 static 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 */
powernow_k6_exit(void)298 static void __exit powernow_k6_exit(void)
299 {
300 cpufreq_unregister_driver(&powernow_k6_driver);
301 release_region(POWERNOW_IOPORT, 16);
302 }
303
304
305 MODULE_AUTHOR("Arjan van de Ven, Dave Jones, "
306 "Dominik Brodowski <linux@brodo.de>");
307 MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
308 MODULE_LICENSE("GPL");
309
310 module_init(powernow_k6_init);
311 module_exit(powernow_k6_exit);
312