2 * Cyrix MediaGX and NatSemi Geode Suspend Modulation
3 * (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>
4 * (C) 2002 Hiroshi Miura <miura@da-cha.org>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * version 2 as published by the Free Software Foundation
11 * The author(s) of this software shall not be held liable for damages
12 * of any nature resulting due to the use of this software. This
13 * software is provided AS-IS with no warranties.
17 * (see Geode(tm) CS5530 manual (rev.4.1) page.56)
19 * CPU frequency control on NatSemi Geode GX1/GXLV processor and CS55x0
20 * are based on Suspend Modulation.
22 * Suspend Modulation works by asserting and de-asserting the SUSP# pin
23 * to CPU(GX1/GXLV) for configurable durations. When asserting SUSP#
24 * the CPU enters an idle state. GX1 stops its core clock when SUSP# is
25 * asserted then power consumption is reduced.
27 * Suspend Modulation's OFF/ON duration are configurable
28 * with 'Suspend Modulation OFF Count Register'
29 * and 'Suspend Modulation ON Count Register'.
30 * These registers are 8bit counters that represent the number of
31 * 32us intervals which the SUSP# pin is asserted(ON)/de-asserted(OFF)
34 * These counters define a ratio which is the effective frequency
35 * of operation of the system.
38 * F_eff = Fgx * ----------------------
39 * OFF Count + ON Count
41 * 0 <= On Count, Off Count <= 255
43 * From these limits, we can get register values
45 * off_duration + on_duration <= MAX_DURATION
46 * on_duration = off_duration * (stock_freq - freq) / freq
48 * off_duration = (freq * DURATION) / stock_freq
49 * on_duration = DURATION - off_duration
52 *---------------------------------------------------------------------------
55 * Dec. 12, 2003 Hiroshi Miura <miura@da-cha.org>
56 * - fix on/off register mistake
57 * - fix cpu_khz calc when it stops cpu modulation.
59 * Dec. 11, 2002 Hiroshi Miura <miura@da-cha.org>
60 * - rewrite for Cyrix MediaGX Cx5510/5520 and
61 * NatSemi Geode Cs5530(A).
63 * Jul. ??, 2002 Zwane Mwaikambo <zwane@commfireservices.com>
64 * - cs5530_mod patch for 2.4.19-rc1.
66 *---------------------------------------------------------------------------
69 * Test on machines with 5510, 5530, 5530A
72 /************************************************************************
73 * Suspend Modulation - Definitions *
74 ************************************************************************/
76 #include <linux/kernel.h>
77 #include <linux/module.h>
78 #include <linux/init.h>
79 #include <linux/smp.h>
80 #include <linux/cpufreq.h>
81 #include <linux/pci.h>
82 #include <linux/errno.h>
83 #include <linux/slab.h>
85 #include <asm/processor-cyrix.h>
87 /* PCI config registers, all at F0 */
88 #define PCI_PMER1 0x80 /* power management enable register 1 */
89 #define PCI_PMER2 0x81 /* power management enable register 2 */
90 #define PCI_PMER3 0x82 /* power management enable register 3 */
91 #define PCI_IRQTC 0x8c /* irq speedup timer counter register:typical 2 to 4ms */
92 #define PCI_VIDTC 0x8d /* video speedup timer counter register: typical 50 to 100ms */
93 #define PCI_MODOFF 0x94 /* suspend modulation OFF counter register, 1 = 32us */
94 #define PCI_MODON 0x95 /* suspend modulation ON counter register */
95 #define PCI_SUSCFG 0x96 /* suspend configuration register */
98 #define GPM (1<<0) /* global power management */
99 #define GIT (1<<1) /* globally enable PM device idle timers */
100 #define GTR (1<<2) /* globally enable IO traps */
101 #define IRQ_SPDUP (1<<3) /* disable clock throttle during interrupt handling */
102 #define VID_SPDUP (1<<4) /* disable clock throttle during vga video handling */
105 #define SUSMOD (1<<0) /* enable/disable suspend modulation */
106 /* the below is supported only with cs5530 (after rev.1.2)/cs5530A */
107 #define SMISPDUP (1<<1) /* select how SMI re-enable suspend modulation: */
108 /* IRQTC timer or read SMI speedup disable reg.(F1BAR[08-09h]) */
109 #define SUSCFG (1<<2) /* enable powering down a GXLV processor. "Special 3Volt Suspend" mode */
110 /* the below is supported only with cs5530A */
111 #define PWRSVE_ISA (1<<3) /* stop ISA clock */
112 #define PWRSVE (1<<4) /* active idle */
114 struct gxfreq_params {
120 struct pci_dev *cs55x0;
123 static struct gxfreq_params *gx_params;
124 static int stock_freq;
126 /* PCI bus clock - defaults to 30.000 if cpu_khz is not available */
127 static int pci_busclk;
128 module_param(pci_busclk, int, 0444);
130 /* maximum duration for which the cpu may be suspended
131 * (32us * MAX_DURATION). If no parameter is given, this defaults
133 * Note that this leads to a maximum of 8 ms(!) where the CPU clock
134 * is suspended -- processing power is just 0.39% of what it used to be,
135 * though. 781.25 kHz(!) for a 200 MHz processor -- wow. */
136 static int max_duration = 255;
137 module_param(max_duration, int, 0444);
139 /* For the default policy, we want at least some processing power
140 * - let's say 5%. (min = maxfreq / POLICY_MIN_DIV)
142 #define POLICY_MIN_DIV 20
145 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \
149 * we can detect a core multipiler from dir0_lsb
150 * from GX1 datasheet p.56,
152 * 0000 = SYSCLK multiplied by 4 (test only)
153 * 0001 = SYSCLK multiplied by 10
154 * 0010 = SYSCLK multiplied by 4
155 * 0011 = SYSCLK multiplied by 6
156 * 0100 = SYSCLK multiplied by 9
157 * 0101 = SYSCLK multiplied by 5
158 * 0110 = SYSCLK multiplied by 7
159 * 0111 = SYSCLK multiplied by 8
162 static int gx_freq_mult[16] = {
163 4, 10, 4, 6, 9, 5, 7, 8,
164 0, 0, 0, 0, 0, 0, 0, 0
168 /****************************************************************
169 * Low Level chipset interface *
170 ****************************************************************/
171 static struct pci_device_id gx_chipset_tbl[] __initdata = {
172 { PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY,
173 PCI_ANY_ID, PCI_ANY_ID },
174 { PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5520,
175 PCI_ANY_ID, PCI_ANY_ID },
176 { PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5510,
177 PCI_ANY_ID, PCI_ANY_ID },
181 static void gx_write_byte(int reg, int value)
183 pci_write_config_byte(gx_params->cs55x0, reg, value);
190 static __init struct pci_dev *gx_detect_chipset(void)
192 struct pci_dev *gx_pci = NULL;
194 /* check if CPU is a MediaGX or a Geode. */
195 if ((boot_cpu_data.x86_vendor != X86_VENDOR_NSC) &&
196 (boot_cpu_data.x86_vendor != X86_VENDOR_CYRIX)) {
197 dprintk("error: no MediaGX/Geode processor found!\n");
201 /* detect which companion chip is used */
202 while ((gx_pci = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, gx_pci)) != NULL) {
203 if ((pci_match_id(gx_chipset_tbl, gx_pci)) != NULL)
207 dprintk("error: no supported chipset found!\n");
214 * Finds out at which efficient frequency the Cyrix MediaGX/NatSemi
217 static unsigned int gx_get_cpuspeed(unsigned int cpu)
219 if ((gx_params->pci_suscfg & SUSMOD) == 0)
222 return (stock_freq * gx_params->off_duration)
223 / (gx_params->on_duration + gx_params->off_duration);
228 * determine current cpu speed
232 static unsigned int gx_validate_speed(unsigned int khz, u8 *on_duration,
237 int old_tmp_freq = stock_freq;
243 for (i = max_duration; i > 0; i--) {
244 tmp_off = ((khz * i) / stock_freq) & 0xff;
245 tmp_on = i - tmp_off;
246 tmp_freq = (stock_freq * tmp_off) / i;
247 /* if this relation is closer to khz, use this. If it's equal,
248 * prefer it, too - lower latency */
249 if (abs(tmp_freq - khz) <= abs(old_tmp_freq - khz)) {
250 *on_duration = tmp_on;
251 *off_duration = tmp_off;
252 old_tmp_freq = tmp_freq;
262 * set cpu speed in khz.
265 static void gx_set_cpuspeed(unsigned int khz)
268 unsigned int new_khz;
270 struct cpufreq_freqs freqs;
273 freqs.old = gx_get_cpuspeed(0);
275 new_khz = gx_validate_speed(khz, &gx_params->on_duration,
276 &gx_params->off_duration);
280 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
281 local_irq_save(flags);
285 if (new_khz != stock_freq) {
286 /* if new khz == 100% of CPU speed, it is special case */
287 switch (gx_params->cs55x0->device) {
288 case PCI_DEVICE_ID_CYRIX_5530_LEGACY:
289 pmer1 = gx_params->pci_pmer1 | IRQ_SPDUP | VID_SPDUP;
290 /* FIXME: need to test other values -- Zwane,Miura */
291 /* typical 2 to 4ms */
292 gx_write_byte(PCI_IRQTC, 4);
293 /* typical 50 to 100ms */
294 gx_write_byte(PCI_VIDTC, 100);
295 gx_write_byte(PCI_PMER1, pmer1);
297 if (gx_params->cs55x0->revision < 0x10) {
298 /* CS5530(rev 1.2, 1.3) */
299 suscfg = gx_params->pci_suscfg|SUSMOD;
302 suscfg = gx_params->pci_suscfg|SUSMOD|PWRSVE;
305 case PCI_DEVICE_ID_CYRIX_5520:
306 case PCI_DEVICE_ID_CYRIX_5510:
307 suscfg = gx_params->pci_suscfg | SUSMOD;
310 local_irq_restore(flags);
311 dprintk("fatal: try to set unknown chipset.\n");
315 suscfg = gx_params->pci_suscfg & ~(SUSMOD);
316 gx_params->off_duration = 0;
317 gx_params->on_duration = 0;
318 dprintk("suspend modulation disabled: cpu runs 100%% speed.\n");
321 gx_write_byte(PCI_MODOFF, gx_params->off_duration);
322 gx_write_byte(PCI_MODON, gx_params->on_duration);
324 gx_write_byte(PCI_SUSCFG, suscfg);
325 pci_read_config_byte(gx_params->cs55x0, PCI_SUSCFG, &suscfg);
327 local_irq_restore(flags);
329 gx_params->pci_suscfg = suscfg;
331 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
333 dprintk("suspend modulation w/ duration of ON:%d us, OFF:%d us\n",
334 gx_params->on_duration * 32, gx_params->off_duration * 32);
335 dprintk("suspend modulation w/ clock speed: %d kHz.\n", freqs.new);
338 /****************************************************************
339 * High level functions *
340 ****************************************************************/
343 * cpufreq_gx_verify: test if frequency range is valid
345 * This function checks if a given frequency range in kHz is valid
346 * for the hardware supported by the driver.
349 static int cpufreq_gx_verify(struct cpufreq_policy *policy)
351 unsigned int tmp_freq = 0;
354 if (!stock_freq || !policy)
358 cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
361 /* it needs to be assured that at least one supported frequency is
362 * within policy->min and policy->max. If it is not, policy->max
363 * needs to be increased until one freuqency is supported.
364 * policy->min may not be decreased, though. This way we guarantee a
365 * specific processing capacity.
367 tmp_freq = gx_validate_speed(policy->min, &tmp1, &tmp2);
368 if (tmp_freq < policy->min)
369 tmp_freq += stock_freq / max_duration;
370 policy->min = tmp_freq;
371 if (policy->min > policy->max)
372 policy->max = tmp_freq;
373 tmp_freq = gx_validate_speed(policy->max, &tmp1, &tmp2);
374 if (tmp_freq > policy->max)
375 tmp_freq -= stock_freq / max_duration;
376 policy->max = tmp_freq;
377 if (policy->max < policy->min)
378 policy->max = policy->min;
379 cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
389 static int cpufreq_gx_target(struct cpufreq_policy *policy,
390 unsigned int target_freq,
391 unsigned int relation)
394 unsigned int tmp_freq;
396 if (!stock_freq || !policy)
401 tmp_freq = gx_validate_speed(target_freq, &tmp1, &tmp2);
402 while (tmp_freq < policy->min) {
403 tmp_freq += stock_freq / max_duration;
404 tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
406 while (tmp_freq > policy->max) {
407 tmp_freq -= stock_freq / max_duration;
408 tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
411 gx_set_cpuspeed(tmp_freq);
416 static int cpufreq_gx_cpu_init(struct cpufreq_policy *policy)
418 unsigned int maxfreq, curfreq;
420 if (!policy || policy->cpu != 0)
423 /* determine maximum frequency */
425 maxfreq = pci_busclk * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
429 maxfreq = 30000 * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
431 stock_freq = maxfreq;
432 curfreq = gx_get_cpuspeed(0);
434 dprintk("cpu max frequency is %d.\n", maxfreq);
435 dprintk("cpu current frequency is %dkHz.\n", curfreq);
437 /* setup basic struct for cpufreq API */
440 if (max_duration < POLICY_MIN_DIV)
441 policy->min = maxfreq / max_duration;
443 policy->min = maxfreq / POLICY_MIN_DIV;
444 policy->max = maxfreq;
445 policy->cur = curfreq;
446 policy->cpuinfo.min_freq = maxfreq / max_duration;
447 policy->cpuinfo.max_freq = maxfreq;
448 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
455 * MediaGX/Geode GX initialize cpufreq driver
457 static struct cpufreq_driver gx_suspmod_driver = {
458 .get = gx_get_cpuspeed,
459 .verify = cpufreq_gx_verify,
460 .target = cpufreq_gx_target,
461 .init = cpufreq_gx_cpu_init,
462 .name = "gx-suspmod",
463 .owner = THIS_MODULE,
466 static int __init cpufreq_gx_init(void)
469 struct gxfreq_params *params;
470 struct pci_dev *gx_pci;
472 /* Test if we have the right hardware */
473 gx_pci = gx_detect_chipset();
477 /* check whether module parameters are sane */
478 if (max_duration > 0xff)
481 dprintk("geode suspend modulation available.\n");
483 params = kzalloc(sizeof(struct gxfreq_params), GFP_KERNEL);
487 params->cs55x0 = gx_pci;
490 /* keep cs55x0 configurations */
491 pci_read_config_byte(params->cs55x0, PCI_SUSCFG, &(params->pci_suscfg));
492 pci_read_config_byte(params->cs55x0, PCI_PMER1, &(params->pci_pmer1));
493 pci_read_config_byte(params->cs55x0, PCI_PMER2, &(params->pci_pmer2));
494 pci_read_config_byte(params->cs55x0, PCI_MODON, &(params->on_duration));
495 pci_read_config_byte(params->cs55x0, PCI_MODOFF,
496 &(params->off_duration));
498 ret = cpufreq_register_driver(&gx_suspmod_driver);
501 return ret; /* register error! */
507 static void __exit cpufreq_gx_exit(void)
509 cpufreq_unregister_driver(&gx_suspmod_driver);
510 pci_dev_put(gx_params->cs55x0);
514 MODULE_AUTHOR("Hiroshi Miura <miura@da-cha.org>");
515 MODULE_DESCRIPTION("Cpufreq driver for Cyrix MediaGX and NatSemi Geode");
516 MODULE_LICENSE("GPL");
518 module_init(cpufreq_gx_init);
519 module_exit(cpufreq_gx_exit);