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); 498 499