1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Cyrix MediaGX and NatSemi Geode Suspend Modulation
4 * (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>
5 * (C) 2002 Hiroshi Miura <miura@da-cha.org>
6 * All Rights Reserved
7 *
8 * The author(s) of this software shall not be held liable for damages
9 * of any nature resulting due to the use of this software. This
10 * software is provided AS-IS with no warranties.
11 *
12 * Theoretical note:
13 *
14 * (see Geode(tm) CS5530 manual (rev.4.1) page.56)
15 *
16 * CPU frequency control on NatSemi Geode GX1/GXLV processor and CS55x0
17 * are based on Suspend Modulation.
18 *
19 * Suspend Modulation works by asserting and de-asserting the SUSP# pin
20 * to CPU(GX1/GXLV) for configurable durations. When asserting SUSP#
21 * the CPU enters an idle state. GX1 stops its core clock when SUSP# is
22 * asserted then power consumption is reduced.
23 *
24 * Suspend Modulation's OFF/ON duration are configurable
25 * with 'Suspend Modulation OFF Count Register'
26 * and 'Suspend Modulation ON Count Register'.
27 * These registers are 8bit counters that represent the number of
28 * 32us intervals which the SUSP# pin is asserted(ON)/de-asserted(OFF)
29 * to the processor.
30 *
31 * These counters define a ratio which is the effective frequency
32 * of operation of the system.
33 *
34 * OFF Count
35 * F_eff = Fgx * ----------------------
36 * OFF Count + ON Count
37 *
38 * 0 <= On Count, Off Count <= 255
39 *
40 * From these limits, we can get register values
41 *
42 * off_duration + on_duration <= MAX_DURATION
43 * on_duration = off_duration * (stock_freq - freq) / freq
44 *
45 * off_duration = (freq * DURATION) / stock_freq
46 * on_duration = DURATION - off_duration
47 *
48 *---------------------------------------------------------------------------
49 *
50 * ChangeLog:
51 * Dec. 12, 2003 Hiroshi Miura <miura@da-cha.org>
52 * - fix on/off register mistake
53 * - fix cpu_khz calc when it stops cpu modulation.
54 *
55 * Dec. 11, 2002 Hiroshi Miura <miura@da-cha.org>
56 * - rewrite for Cyrix MediaGX Cx5510/5520 and
57 * NatSemi Geode Cs5530(A).
58 *
59 * Jul. ??, 2002 Zwane Mwaikambo <zwane@commfireservices.com>
60 * - cs5530_mod patch for 2.4.19-rc1.
61 *
62 *---------------------------------------------------------------------------
63 *
64 * Todo
65 * Test on machines with 5510, 5530, 5530A
66 */
67
68 /************************************************************************
69 * Suspend Modulation - Definitions *
70 ************************************************************************/
71
72 #include <linux/kernel.h>
73 #include <linux/module.h>
74 #include <linux/init.h>
75 #include <linux/smp.h>
76 #include <linux/cpufreq.h>
77 #include <linux/pci.h>
78 #include <linux/errno.h>
79 #include <linux/slab.h>
80
81 #include <asm/cpu_device_id.h>
82 #include <asm/processor-cyrix.h>
83
84 /* PCI config registers, all at F0 */
85 #define PCI_PMER1 0x80 /* power management enable register 1 */
86 #define PCI_PMER2 0x81 /* power management enable register 2 */
87 #define PCI_PMER3 0x82 /* power management enable register 3 */
88 #define PCI_IRQTC 0x8c /* irq speedup timer counter register:typical 2 to 4ms */
89 #define PCI_VIDTC 0x8d /* video speedup timer counter register: typical 50 to 100ms */
90 #define PCI_MODOFF 0x94 /* suspend modulation OFF counter register, 1 = 32us */
91 #define PCI_MODON 0x95 /* suspend modulation ON counter register */
92 #define PCI_SUSCFG 0x96 /* suspend configuration register */
93
94 /* PMER1 bits */
95 #define GPM (1<<0) /* global power management */
96 #define GIT (1<<1) /* globally enable PM device idle timers */
97 #define GTR (1<<2) /* globally enable IO traps */
98 #define IRQ_SPDUP (1<<3) /* disable clock throttle during interrupt handling */
99 #define VID_SPDUP (1<<4) /* disable clock throttle during vga video handling */
100
101 /* SUSCFG bits */
102 #define SUSMOD (1<<0) /* enable/disable suspend modulation */
103 /* the below is supported only with cs5530 (after rev.1.2)/cs5530A */
104 #define SMISPDUP (1<<1) /* select how SMI re-enable suspend modulation: */
105 /* IRQTC timer or read SMI speedup disable reg.(F1BAR[08-09h]) */
106 #define SUSCFG (1<<2) /* enable powering down a GXLV processor. "Special 3Volt Suspend" mode */
107 /* the below is supported only with cs5530A */
108 #define PWRSVE_ISA (1<<3) /* stop ISA clock */
109 #define PWRSVE (1<<4) /* active idle */
110
111 struct gxfreq_params {
112 u8 on_duration;
113 u8 off_duration;
114 u8 pci_suscfg;
115 u8 pci_pmer1;
116 u8 pci_pmer2;
117 struct pci_dev *cs55x0;
118 };
119
120 static struct gxfreq_params *gx_params;
121 static int stock_freq;
122
123 /* PCI bus clock - defaults to 30.000 if cpu_khz is not available */
124 static int pci_busclk;
125 module_param(pci_busclk, int, 0444);
126
127 /* maximum duration for which the cpu may be suspended
128 * (32us * MAX_DURATION). If no parameter is given, this defaults
129 * to 255.
130 * Note that this leads to a maximum of 8 ms(!) where the CPU clock
131 * is suspended -- processing power is just 0.39% of what it used to be,
132 * though. 781.25 kHz(!) for a 200 MHz processor -- wow. */
133 static int max_duration = 255;
134 module_param(max_duration, int, 0444);
135
136 /* For the default policy, we want at least some processing power
137 * - let's say 5%. (min = maxfreq / POLICY_MIN_DIV)
138 */
139 #define POLICY_MIN_DIV 20
140
141
142 /**
143 * we can detect a core multiplier from dir0_lsb
144 * from GX1 datasheet p.56,
145 * MULT[3:0]:
146 * 0000 = SYSCLK multiplied by 4 (test only)
147 * 0001 = SYSCLK multiplied by 10
148 * 0010 = SYSCLK multiplied by 4
149 * 0011 = SYSCLK multiplied by 6
150 * 0100 = SYSCLK multiplied by 9
151 * 0101 = SYSCLK multiplied by 5
152 * 0110 = SYSCLK multiplied by 7
153 * 0111 = SYSCLK multiplied by 8
154 * of 33.3MHz
155 **/
156 static int gx_freq_mult[16] = {
157 4, 10, 4, 6, 9, 5, 7, 8,
158 0, 0, 0, 0, 0, 0, 0, 0
159 };
160
161
162 /****************************************************************
163 * Low Level chipset interface *
164 ****************************************************************/
165 static struct pci_device_id gx_chipset_tbl[] __initdata = {
166 { PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY), },
167 { PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5520), },
168 { PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5510), },
169 { 0, },
170 };
171 MODULE_DEVICE_TABLE(pci, gx_chipset_tbl);
172
173 static void gx_write_byte(int reg, int value)
174 {
175 pci_write_config_byte(gx_params->cs55x0, reg, value);
176 }
177
178 /**
179 * gx_detect_chipset:
180 *
181 **/
182 static struct pci_dev * __init gx_detect_chipset(void)
183 {
184 struct pci_dev *gx_pci = NULL;
185
186 /* detect which companion chip is used */
187 for_each_pci_dev(gx_pci) {
188 if ((pci_match_id(gx_chipset_tbl, gx_pci)) != NULL)
189 return gx_pci;
190 }
191
192 pr_debug("error: no supported chipset found!\n");
193 return NULL;
194 }
195
196 /**
197 * gx_get_cpuspeed:
198 *
199 * Finds out at which efficient frequency the Cyrix MediaGX/NatSemi
200 * Geode CPU runs.
201 */
202 static unsigned int gx_get_cpuspeed(unsigned int cpu)
203 {
204 if ((gx_params->pci_suscfg & SUSMOD) == 0)
205 return stock_freq;
206
207 return (stock_freq * gx_params->off_duration)
208 / (gx_params->on_duration + gx_params->off_duration);
209 }
210
211 /**
212 * gx_validate_speed:
213 * determine current cpu speed
214 *
215 **/
216
217 static unsigned int gx_validate_speed(unsigned int khz, u8 *on_duration,
218 u8 *off_duration)
219 {
220 unsigned int i;
221 u8 tmp_on, tmp_off;
222 int old_tmp_freq = stock_freq;
223 int tmp_freq;
224
225 *off_duration = 1;
226 *on_duration = 0;
227
228 for (i = max_duration; i > 0; i--) {
229 tmp_off = ((khz * i) / stock_freq) & 0xff;
230 tmp_on = i - tmp_off;
231 tmp_freq = (stock_freq * tmp_off) / i;
232 /* if this relation is closer to khz, use this. If it's equal,
233 * prefer it, too - lower latency */
234 if (abs(tmp_freq - khz) <= abs(old_tmp_freq - khz)) {
235 *on_duration = tmp_on;
236 *off_duration = tmp_off;
237 old_tmp_freq = tmp_freq;
238 }
239 }
240
241 return old_tmp_freq;
242 }
243
244
245 /**
246 * gx_set_cpuspeed:
247 * set cpu speed in khz.
248 **/
249
250 static void gx_set_cpuspeed(struct cpufreq_policy *policy, unsigned int khz)
251 {
252 u8 suscfg, pmer1;
253 unsigned int new_khz;
254 unsigned long flags;
255 struct cpufreq_freqs freqs;
256
257 freqs.old = gx_get_cpuspeed(0);
258
259 new_khz = gx_validate_speed(khz, &gx_params->on_duration,
260 &gx_params->off_duration);
261
262 freqs.new = new_khz;
263
264 cpufreq_freq_transition_begin(policy, &freqs);
265 local_irq_save(flags);
266
267 if (new_khz != stock_freq) {
268 /* if new khz == 100% of CPU speed, it is special case */
269 switch (gx_params->cs55x0->device) {
270 case PCI_DEVICE_ID_CYRIX_5530_LEGACY:
271 pmer1 = gx_params->pci_pmer1 | IRQ_SPDUP | VID_SPDUP;
272 /* FIXME: need to test other values -- Zwane,Miura */
273 /* typical 2 to 4ms */
274 gx_write_byte(PCI_IRQTC, 4);
275 /* typical 50 to 100ms */
276 gx_write_byte(PCI_VIDTC, 100);
277 gx_write_byte(PCI_PMER1, pmer1);
278
279 if (gx_params->cs55x0->revision < 0x10) {
280 /* CS5530(rev 1.2, 1.3) */
281 suscfg = gx_params->pci_suscfg|SUSMOD;
282 } else {
283 /* CS5530A,B.. */
284 suscfg = gx_params->pci_suscfg|SUSMOD|PWRSVE;
285 }
286 break;
287 case PCI_DEVICE_ID_CYRIX_5520:
288 case PCI_DEVICE_ID_CYRIX_5510:
289 suscfg = gx_params->pci_suscfg | SUSMOD;
290 break;
291 default:
292 local_irq_restore(flags);
293 pr_debug("fatal: try to set unknown chipset.\n");
294 return;
295 }
296 } else {
297 suscfg = gx_params->pci_suscfg & ~(SUSMOD);
298 gx_params->off_duration = 0;
299 gx_params->on_duration = 0;
300 pr_debug("suspend modulation disabled: cpu runs 100%% speed.\n");
301 }
302
303 gx_write_byte(PCI_MODOFF, gx_params->off_duration);
304 gx_write_byte(PCI_MODON, gx_params->on_duration);
305
306 gx_write_byte(PCI_SUSCFG, suscfg);
307 pci_read_config_byte(gx_params->cs55x0, PCI_SUSCFG, &suscfg);
308
309 local_irq_restore(flags);
310
311 gx_params->pci_suscfg = suscfg;
312
313 cpufreq_freq_transition_end(policy, &freqs, 0);
314
315 pr_debug("suspend modulation w/ duration of ON:%d us, OFF:%d us\n",
316 gx_params->on_duration * 32, gx_params->off_duration * 32);
317 pr_debug("suspend modulation w/ clock speed: %d kHz.\n", freqs.new);
318 }
319
320 /****************************************************************
321 * High level functions *
322 ****************************************************************/
323
324 /*
325 * cpufreq_gx_verify: test if frequency range is valid
326 *
327 * This function checks if a given frequency range in kHz is valid
328 * for the hardware supported by the driver.
329 */
330
331 static int cpufreq_gx_verify(struct cpufreq_policy_data *policy)
332 {
333 unsigned int tmp_freq = 0;
334 u8 tmp1, tmp2;
335
336 if (!stock_freq || !policy)
337 return -EINVAL;
338
339 policy->cpu = 0;
340 cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
341 stock_freq);
342
343 /* it needs to be assured that at least one supported frequency is
344 * within policy->min and policy->max. If it is not, policy->max
345 * needs to be increased until one frequency is supported.
346 * policy->min may not be decreased, though. This way we guarantee a
347 * specific processing capacity.
348 */
349 tmp_freq = gx_validate_speed(policy->min, &tmp1, &tmp2);
350 if (tmp_freq < policy->min)
351 tmp_freq += stock_freq / max_duration;
352 policy->min = tmp_freq;
353 if (policy->min > policy->max)
354 policy->max = tmp_freq;
355 tmp_freq = gx_validate_speed(policy->max, &tmp1, &tmp2);
356 if (tmp_freq > policy->max)
357 tmp_freq -= stock_freq / max_duration;
358 policy->max = tmp_freq;
359 if (policy->max < policy->min)
360 policy->max = policy->min;
361 cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
362 stock_freq);
363
364 return 0;
365 }
366
367 /*
368 * cpufreq_gx_target:
369 *
370 */
371 static int cpufreq_gx_target(struct cpufreq_policy *policy,
372 unsigned int target_freq,
373 unsigned int relation)
374 {
375 u8 tmp1, tmp2;
376 unsigned int tmp_freq;
377
378 if (!stock_freq || !policy)
379 return -EINVAL;
380
381 policy->cpu = 0;
382
383 tmp_freq = gx_validate_speed(target_freq, &tmp1, &tmp2);
384 while (tmp_freq < policy->min) {
385 tmp_freq += stock_freq / max_duration;
386 tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
387 }
388 while (tmp_freq > policy->max) {
389 tmp_freq -= stock_freq / max_duration;
390 tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
391 }
392
393 gx_set_cpuspeed(policy, tmp_freq);
394
395 return 0;
396 }
397
398 static int cpufreq_gx_cpu_init(struct cpufreq_policy *policy)
399 {
400 unsigned int maxfreq;
401
402 if (!policy || policy->cpu != 0)
403 return -ENODEV;
404
405 /* determine maximum frequency */
406 if (pci_busclk)
407 maxfreq = pci_busclk * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
408 else if (cpu_khz)
409 maxfreq = cpu_khz;
410 else
411 maxfreq = 30000 * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
412
413 stock_freq = maxfreq;
414
415 pr_debug("cpu max frequency is %d.\n", maxfreq);
416
417 /* setup basic struct for cpufreq API */
418 policy->cpu = 0;
419
420 if (max_duration < POLICY_MIN_DIV)
421 policy->min = maxfreq / max_duration;
422 else
423 policy->min = maxfreq / POLICY_MIN_DIV;
424 policy->max = maxfreq;
425 policy->cpuinfo.min_freq = maxfreq / max_duration;
426 policy->cpuinfo.max_freq = maxfreq;
427
428 return 0;
429 }
430
431 /*
432 * cpufreq_gx_init:
433 * MediaGX/Geode GX initialize cpufreq driver
434 */
435 static struct cpufreq_driver gx_suspmod_driver = {
436 .flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
437 .get = gx_get_cpuspeed,
438 .verify = cpufreq_gx_verify,
439 .target = cpufreq_gx_target,
440 .init = cpufreq_gx_cpu_init,
441 .name = "gx-suspmod",
442 };
443
444 static int __init cpufreq_gx_init(void)
445 {
446 int ret;
447 struct gxfreq_params *params;
448 struct pci_dev *gx_pci;
449
450 /* Test if we have the right hardware */
451 gx_pci = gx_detect_chipset();
452 if (gx_pci == NULL)
453 return -ENODEV;
454
455 /* check whether module parameters are sane */
456 if (max_duration > 0xff)
457 max_duration = 0xff;
458
459 pr_debug("geode suspend modulation available.\n");
460
461 params = kzalloc(sizeof(*params), GFP_KERNEL);
462 if (params == NULL)
463 return -ENOMEM;
464
465 params->cs55x0 = gx_pci;
466 gx_params = params;
467
468 /* keep cs55x0 configurations */
469 pci_read_config_byte(params->cs55x0, PCI_SUSCFG, &(params->pci_suscfg));
470 pci_read_config_byte(params->cs55x0, PCI_PMER1, &(params->pci_pmer1));
471 pci_read_config_byte(params->cs55x0, PCI_PMER2, &(params->pci_pmer2));
472 pci_read_config_byte(params->cs55x0, PCI_MODON, &(params->on_duration));
473 pci_read_config_byte(params->cs55x0, PCI_MODOFF,
474 &(params->off_duration));
475
476 ret = cpufreq_register_driver(&gx_suspmod_driver);
477 if (ret) {
478 kfree(params);
479 return ret; /* register error! */
480 }
481
482 return 0;
483 }
484
485 static void __exit cpufreq_gx_exit(void)
486 {
487 cpufreq_unregister_driver(&gx_suspmod_driver);
488 pci_dev_put(gx_params->cs55x0);
489 kfree(gx_params);
490 }
491
492 MODULE_AUTHOR("Hiroshi Miura <miura@da-cha.org>");
493 MODULE_DESCRIPTION("Cpufreq driver for Cyrix MediaGX and NatSemi Geode");
494 MODULE_LICENSE("GPL");
495
496 module_init(cpufreq_gx_init);
497 module_exit(cpufreq_gx_exit);
498