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bfc0f594 | 1 | #include <linux/kernel.h> |
0ef95533 AK |
2 | #include <linux/sched.h> |
3 | #include <linux/init.h> | |
4 | #include <linux/module.h> | |
5 | #include <linux/timer.h> | |
bfc0f594 | 6 | #include <linux/acpi_pmtmr.h> |
2dbe06fa | 7 | #include <linux/cpufreq.h> |
bfc0f594 AK |
8 | |
9 | #include <asm/hpet.h> | |
0ef95533 AK |
10 | |
11 | unsigned int cpu_khz; /* TSC clocks / usec, not used here */ | |
12 | EXPORT_SYMBOL(cpu_khz); | |
13 | unsigned int tsc_khz; | |
14 | EXPORT_SYMBOL(tsc_khz); | |
15 | ||
16 | /* | |
17 | * TSC can be unstable due to cpufreq or due to unsynced TSCs | |
18 | */ | |
19 | int tsc_unstable; | |
20 | ||
21 | /* native_sched_clock() is called before tsc_init(), so | |
22 | we must start with the TSC soft disabled to prevent | |
23 | erroneous rdtsc usage on !cpu_has_tsc processors */ | |
24 | int tsc_disabled = -1; | |
25 | ||
26 | /* | |
27 | * Scheduler clock - returns current time in nanosec units. | |
28 | */ | |
29 | u64 native_sched_clock(void) | |
30 | { | |
31 | u64 this_offset; | |
32 | ||
33 | /* | |
34 | * Fall back to jiffies if there's no TSC available: | |
35 | * ( But note that we still use it if the TSC is marked | |
36 | * unstable. We do this because unlike Time Of Day, | |
37 | * the scheduler clock tolerates small errors and it's | |
38 | * very important for it to be as fast as the platform | |
39 | * can achive it. ) | |
40 | */ | |
41 | if (unlikely(tsc_disabled)) { | |
42 | /* No locking but a rare wrong value is not a big deal: */ | |
43 | return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); | |
44 | } | |
45 | ||
46 | /* read the Time Stamp Counter: */ | |
47 | rdtscll(this_offset); | |
48 | ||
49 | /* return the value in ns */ | |
50 | return cycles_2_ns(this_offset); | |
51 | } | |
52 | ||
53 | /* We need to define a real function for sched_clock, to override the | |
54 | weak default version */ | |
55 | #ifdef CONFIG_PARAVIRT | |
56 | unsigned long long sched_clock(void) | |
57 | { | |
58 | return paravirt_sched_clock(); | |
59 | } | |
60 | #else | |
61 | unsigned long long | |
62 | sched_clock(void) __attribute__((alias("native_sched_clock"))); | |
63 | #endif | |
64 | ||
65 | int check_tsc_unstable(void) | |
66 | { | |
67 | return tsc_unstable; | |
68 | } | |
69 | EXPORT_SYMBOL_GPL(check_tsc_unstable); | |
70 | ||
71 | #ifdef CONFIG_X86_TSC | |
72 | int __init notsc_setup(char *str) | |
73 | { | |
74 | printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, " | |
75 | "cannot disable TSC completely.\n"); | |
76 | tsc_disabled = 1; | |
77 | return 1; | |
78 | } | |
79 | #else | |
80 | /* | |
81 | * disable flag for tsc. Takes effect by clearing the TSC cpu flag | |
82 | * in cpu/common.c | |
83 | */ | |
84 | int __init notsc_setup(char *str) | |
85 | { | |
86 | setup_clear_cpu_cap(X86_FEATURE_TSC); | |
87 | return 1; | |
88 | } | |
89 | #endif | |
90 | ||
91 | __setup("notsc", notsc_setup); | |
bfc0f594 AK |
92 | |
93 | #define MAX_RETRIES 5 | |
94 | #define SMI_TRESHOLD 50000 | |
95 | ||
96 | /* | |
97 | * Read TSC and the reference counters. Take care of SMI disturbance | |
98 | */ | |
99 | static u64 __init tsc_read_refs(u64 *pm, u64 *hpet) | |
100 | { | |
101 | u64 t1, t2; | |
102 | int i; | |
103 | ||
104 | for (i = 0; i < MAX_RETRIES; i++) { | |
105 | t1 = get_cycles(); | |
106 | if (hpet) | |
107 | *hpet = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF; | |
108 | else | |
109 | *pm = acpi_pm_read_early(); | |
110 | t2 = get_cycles(); | |
111 | if ((t2 - t1) < SMI_TRESHOLD) | |
112 | return t2; | |
113 | } | |
114 | return ULLONG_MAX; | |
115 | } | |
116 | ||
117 | /** | |
118 | * tsc_calibrate - calibrate the tsc on boot | |
119 | */ | |
120 | static unsigned int __init tsc_calibrate(void) | |
121 | { | |
122 | unsigned long flags; | |
123 | u64 tsc1, tsc2, tr1, tr2, delta, pm1, pm2, hpet1, hpet2; | |
124 | int hpet = is_hpet_enabled(); | |
125 | unsigned int tsc_khz_val = 0; | |
126 | ||
127 | local_irq_save(flags); | |
128 | ||
129 | tsc1 = tsc_read_refs(&pm1, hpet ? &hpet1 : NULL); | |
130 | ||
131 | outb((inb(0x61) & ~0x02) | 0x01, 0x61); | |
132 | ||
133 | outb(0xb0, 0x43); | |
134 | outb((CLOCK_TICK_RATE / (1000 / 50)) & 0xff, 0x42); | |
135 | outb((CLOCK_TICK_RATE / (1000 / 50)) >> 8, 0x42); | |
136 | tr1 = get_cycles(); | |
137 | while ((inb(0x61) & 0x20) == 0); | |
138 | tr2 = get_cycles(); | |
139 | ||
140 | tsc2 = tsc_read_refs(&pm2, hpet ? &hpet2 : NULL); | |
141 | ||
142 | local_irq_restore(flags); | |
143 | ||
144 | /* | |
145 | * Preset the result with the raw and inaccurate PIT | |
146 | * calibration value | |
147 | */ | |
148 | delta = (tr2 - tr1); | |
149 | do_div(delta, 50); | |
150 | tsc_khz_val = delta; | |
151 | ||
152 | /* hpet or pmtimer available ? */ | |
153 | if (!hpet && !pm1 && !pm2) { | |
154 | printk(KERN_INFO "TSC calibrated against PIT\n"); | |
155 | goto out; | |
156 | } | |
157 | ||
158 | /* Check, whether the sampling was disturbed by an SMI */ | |
159 | if (tsc1 == ULLONG_MAX || tsc2 == ULLONG_MAX) { | |
160 | printk(KERN_WARNING "TSC calibration disturbed by SMI, " | |
161 | "using PIT calibration result\n"); | |
162 | goto out; | |
163 | } | |
164 | ||
165 | tsc2 = (tsc2 - tsc1) * 1000000LL; | |
166 | ||
167 | if (hpet) { | |
168 | printk(KERN_INFO "TSC calibrated against HPET\n"); | |
169 | if (hpet2 < hpet1) | |
170 | hpet2 += 0x100000000ULL; | |
171 | hpet2 -= hpet1; | |
172 | tsc1 = ((u64)hpet2 * hpet_readl(HPET_PERIOD)); | |
173 | do_div(tsc1, 1000000); | |
174 | } else { | |
175 | printk(KERN_INFO "TSC calibrated against PM_TIMER\n"); | |
176 | if (pm2 < pm1) | |
177 | pm2 += (u64)ACPI_PM_OVRRUN; | |
178 | pm2 -= pm1; | |
179 | tsc1 = pm2 * 1000000000LL; | |
180 | do_div(tsc1, PMTMR_TICKS_PER_SEC); | |
181 | } | |
182 | ||
183 | do_div(tsc2, tsc1); | |
184 | tsc_khz_val = tsc2; | |
185 | ||
186 | out: | |
187 | return tsc_khz_val; | |
188 | } | |
189 | ||
190 | unsigned long native_calculate_cpu_khz(void) | |
191 | { | |
192 | return tsc_calibrate(); | |
193 | } | |
194 | ||
195 | #ifdef CONFIG_X86_32 | |
196 | /* Only called from the Powernow K7 cpu freq driver */ | |
197 | int recalibrate_cpu_khz(void) | |
198 | { | |
199 | #ifndef CONFIG_SMP | |
200 | unsigned long cpu_khz_old = cpu_khz; | |
201 | ||
202 | if (cpu_has_tsc) { | |
203 | cpu_khz = calculate_cpu_khz(); | |
204 | tsc_khz = cpu_khz; | |
205 | cpu_data(0).loops_per_jiffy = | |
206 | cpufreq_scale(cpu_data(0).loops_per_jiffy, | |
207 | cpu_khz_old, cpu_khz); | |
208 | return 0; | |
209 | } else | |
210 | return -ENODEV; | |
211 | #else | |
212 | return -ENODEV; | |
213 | #endif | |
214 | } | |
215 | ||
216 | EXPORT_SYMBOL(recalibrate_cpu_khz); | |
217 | ||
218 | #endif /* CONFIG_X86_32 */ | |
2dbe06fa AK |
219 | |
220 | /* Accelerators for sched_clock() | |
221 | * convert from cycles(64bits) => nanoseconds (64bits) | |
222 | * basic equation: | |
223 | * ns = cycles / (freq / ns_per_sec) | |
224 | * ns = cycles * (ns_per_sec / freq) | |
225 | * ns = cycles * (10^9 / (cpu_khz * 10^3)) | |
226 | * ns = cycles * (10^6 / cpu_khz) | |
227 | * | |
228 | * Then we use scaling math (suggested by george@mvista.com) to get: | |
229 | * ns = cycles * (10^6 * SC / cpu_khz) / SC | |
230 | * ns = cycles * cyc2ns_scale / SC | |
231 | * | |
232 | * And since SC is a constant power of two, we can convert the div | |
233 | * into a shift. | |
234 | * | |
235 | * We can use khz divisor instead of mhz to keep a better precision, since | |
236 | * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. | |
237 | * (mathieu.desnoyers@polymtl.ca) | |
238 | * | |
239 | * -johnstul@us.ibm.com "math is hard, lets go shopping!" | |
240 | */ | |
241 | ||
242 | DEFINE_PER_CPU(unsigned long, cyc2ns); | |
243 | ||
244 | void set_cyc2ns_scale(unsigned long cpu_khz, int cpu) | |
245 | { | |
246 | unsigned long long tsc_now, ns_now; | |
247 | unsigned long flags, *scale; | |
248 | ||
249 | local_irq_save(flags); | |
250 | sched_clock_idle_sleep_event(); | |
251 | ||
252 | scale = &per_cpu(cyc2ns, cpu); | |
253 | ||
254 | rdtscll(tsc_now); | |
255 | ns_now = __cycles_2_ns(tsc_now); | |
256 | ||
257 | if (cpu_khz) | |
258 | *scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz; | |
259 | ||
260 | sched_clock_idle_wakeup_event(0); | |
261 | local_irq_restore(flags); | |
262 | } | |
263 | ||
264 | #ifdef CONFIG_CPU_FREQ | |
265 | ||
266 | /* Frequency scaling support. Adjust the TSC based timer when the cpu frequency | |
267 | * changes. | |
268 | * | |
269 | * RED-PEN: On SMP we assume all CPUs run with the same frequency. It's | |
270 | * not that important because current Opteron setups do not support | |
271 | * scaling on SMP anyroads. | |
272 | * | |
273 | * Should fix up last_tsc too. Currently gettimeofday in the | |
274 | * first tick after the change will be slightly wrong. | |
275 | */ | |
276 | ||
277 | static unsigned int ref_freq; | |
278 | static unsigned long loops_per_jiffy_ref; | |
279 | static unsigned long tsc_khz_ref; | |
280 | ||
281 | static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, | |
282 | void *data) | |
283 | { | |
284 | struct cpufreq_freqs *freq = data; | |
285 | unsigned long *lpj, dummy; | |
286 | ||
287 | if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC)) | |
288 | return 0; | |
289 | ||
290 | lpj = &dummy; | |
291 | if (!(freq->flags & CPUFREQ_CONST_LOOPS)) | |
292 | #ifdef CONFIG_SMP | |
293 | lpj = &cpu_data(freq->cpu).loops_per_jiffy; | |
294 | #else | |
295 | lpj = &boot_cpu_data.loops_per_jiffy; | |
296 | #endif | |
297 | ||
298 | if (!ref_freq) { | |
299 | ref_freq = freq->old; | |
300 | loops_per_jiffy_ref = *lpj; | |
301 | tsc_khz_ref = tsc_khz; | |
302 | } | |
303 | if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || | |
304 | (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) || | |
305 | (val == CPUFREQ_RESUMECHANGE)) { | |
306 | *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); | |
307 | ||
308 | tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); | |
309 | if (!(freq->flags & CPUFREQ_CONST_LOOPS)) | |
310 | mark_tsc_unstable("cpufreq changes"); | |
311 | } | |
312 | ||
313 | set_cyc2ns_scale(tsc_khz_ref, freq->cpu); | |
314 | ||
315 | return 0; | |
316 | } | |
317 | ||
318 | static struct notifier_block time_cpufreq_notifier_block = { | |
319 | .notifier_call = time_cpufreq_notifier | |
320 | }; | |
321 | ||
322 | static int __init cpufreq_tsc(void) | |
323 | { | |
324 | cpufreq_register_notifier(&time_cpufreq_notifier_block, | |
325 | CPUFREQ_TRANSITION_NOTIFIER); | |
326 | return 0; | |
327 | } | |
328 | ||
329 | core_initcall(cpufreq_tsc); | |
330 | ||
331 | #endif /* CONFIG_CPU_FREQ */ |