1 /*
2  * CPPC (Collaborative Processor Performance Control) driver for
3  * interfacing with the CPUfreq layer and governors. See
4  * cppc_acpi.c for CPPC specific methods.
5  *
6  * (C) Copyright 2014, 2015 Linaro Ltd.
7  * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License
11  * as published by the Free Software Foundation; version 2
12  * of the License.
13  */
14 
15 #define pr_fmt(fmt)	"CPPC Cpufreq:"	fmt
16 
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/delay.h>
20 #include <linux/cpu.h>
21 #include <linux/cpufreq.h>
22 #include <linux/dmi.h>
23 #include <linux/time.h>
24 #include <linux/vmalloc.h>
25 
26 #include <asm/unaligned.h>
27 
28 #include <acpi/cppc_acpi.h>
29 
30 /* Minimum struct length needed for the DMI processor entry we want */
31 #define DMI_ENTRY_PROCESSOR_MIN_LENGTH	48
32 
33 /* Offest in the DMI processor structure for the max frequency */
34 #define DMI_PROCESSOR_MAX_SPEED  0x14
35 
36 /*
37  * These structs contain information parsed from per CPU
38  * ACPI _CPC structures.
39  * e.g. For each CPU the highest, lowest supported
40  * performance capabilities, desired performance level
41  * requested etc.
42  */
43 static struct cppc_cpudata **all_cpu_data;
44 
45 struct cppc_workaround_oem_info {
46 	char oem_id[ACPI_OEM_ID_SIZE +1];
47 	char oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1];
48 	u32 oem_revision;
49 };
50 
51 static bool apply_hisi_workaround;
52 
53 static struct cppc_workaround_oem_info wa_info[] = {
54 	{
55 		.oem_id		= "HISI  ",
56 		.oem_table_id	= "HIP07   ",
57 		.oem_revision	= 0,
58 	}, {
59 		.oem_id		= "HISI  ",
60 		.oem_table_id	= "HIP08   ",
61 		.oem_revision	= 0,
62 	}
63 };
64 
65 static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu,
66 					unsigned int perf);
67 
68 /*
69  * HISI platform does not support delivered performance counter and
70  * reference performance counter. It can calculate the performance using the
71  * platform specific mechanism. We reuse the desired performance register to
72  * store the real performance calculated by the platform.
73  */
74 static unsigned int hisi_cppc_cpufreq_get_rate(unsigned int cpunum)
75 {
76 	struct cppc_cpudata *cpudata = all_cpu_data[cpunum];
77 	u64 desired_perf;
78 	int ret;
79 
80 	ret = cppc_get_desired_perf(cpunum, &desired_perf);
81 	if (ret < 0)
82 		return -EIO;
83 
84 	return cppc_cpufreq_perf_to_khz(cpudata, desired_perf);
85 }
86 
87 static void cppc_check_hisi_workaround(void)
88 {
89 	struct acpi_table_header *tbl;
90 	acpi_status status = AE_OK;
91 	int i;
92 
93 	status = acpi_get_table(ACPI_SIG_PCCT, 0, &tbl);
94 	if (ACPI_FAILURE(status) || !tbl)
95 		return;
96 
97 	for (i = 0; i < ARRAY_SIZE(wa_info); i++) {
98 		if (!memcmp(wa_info[i].oem_id, tbl->oem_id, ACPI_OEM_ID_SIZE) &&
99 		    !memcmp(wa_info[i].oem_table_id, tbl->oem_table_id, ACPI_OEM_TABLE_ID_SIZE) &&
100 		    wa_info[i].oem_revision == tbl->oem_revision)
101 			apply_hisi_workaround = true;
102 	}
103 }
104 
105 /* Callback function used to retrieve the max frequency from DMI */
106 static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
107 {
108 	const u8 *dmi_data = (const u8 *)dm;
109 	u16 *mhz = (u16 *)private;
110 
111 	if (dm->type == DMI_ENTRY_PROCESSOR &&
112 	    dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
113 		u16 val = (u16)get_unaligned((const u16 *)
114 				(dmi_data + DMI_PROCESSOR_MAX_SPEED));
115 		*mhz = val > *mhz ? val : *mhz;
116 	}
117 }
118 
119 /* Look up the max frequency in DMI */
120 static u64 cppc_get_dmi_max_khz(void)
121 {
122 	u16 mhz = 0;
123 
124 	dmi_walk(cppc_find_dmi_mhz, &mhz);
125 
126 	/*
127 	 * Real stupid fallback value, just in case there is no
128 	 * actual value set.
129 	 */
130 	mhz = mhz ? mhz : 1;
131 
132 	return (1000 * mhz);
133 }
134 
135 /*
136  * If CPPC lowest_freq and nominal_freq registers are exposed then we can
137  * use them to convert perf to freq and vice versa
138  *
139  * If the perf/freq point lies between Nominal and Lowest, we can treat
140  * (Low perf, Low freq) and (Nom Perf, Nom freq) as 2D co-ordinates of a line
141  * and extrapolate the rest
142  * For perf/freq > Nominal, we use the ratio perf:freq at Nominal for conversion
143  */
144 static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu,
145 					unsigned int perf)
146 {
147 	static u64 max_khz;
148 	struct cppc_perf_caps *caps = &cpu->perf_caps;
149 	u64 mul, div;
150 
151 	if (caps->lowest_freq && caps->nominal_freq) {
152 		if (perf >= caps->nominal_perf) {
153 			mul = caps->nominal_freq;
154 			div = caps->nominal_perf;
155 		} else {
156 			mul = caps->nominal_freq - caps->lowest_freq;
157 			div = caps->nominal_perf - caps->lowest_perf;
158 		}
159 	} else {
160 		if (!max_khz)
161 			max_khz = cppc_get_dmi_max_khz();
162 		mul = max_khz;
163 		div = cpu->perf_caps.highest_perf;
164 	}
165 	return (u64)perf * mul / div;
166 }
167 
168 static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu,
169 					unsigned int freq)
170 {
171 	static u64 max_khz;
172 	struct cppc_perf_caps *caps = &cpu->perf_caps;
173 	u64  mul, div;
174 
175 	if (caps->lowest_freq && caps->nominal_freq) {
176 		if (freq >= caps->nominal_freq) {
177 			mul = caps->nominal_perf;
178 			div = caps->nominal_freq;
179 		} else {
180 			mul = caps->lowest_perf;
181 			div = caps->lowest_freq;
182 		}
183 	} else {
184 		if (!max_khz)
185 			max_khz = cppc_get_dmi_max_khz();
186 		mul = cpu->perf_caps.highest_perf;
187 		div = max_khz;
188 	}
189 
190 	return (u64)freq * mul / div;
191 }
192 
193 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
194 		unsigned int target_freq,
195 		unsigned int relation)
196 {
197 	struct cppc_cpudata *cpu;
198 	struct cpufreq_freqs freqs;
199 	u32 desired_perf;
200 	int ret = 0;
201 
202 	cpu = all_cpu_data[policy->cpu];
203 
204 	desired_perf = cppc_cpufreq_khz_to_perf(cpu, target_freq);
205 	/* Return if it is exactly the same perf */
206 	if (desired_perf == cpu->perf_ctrls.desired_perf)
207 		return ret;
208 
209 	cpu->perf_ctrls.desired_perf = desired_perf;
210 	freqs.old = policy->cur;
211 	freqs.new = target_freq;
212 
213 	cpufreq_freq_transition_begin(policy, &freqs);
214 	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
215 	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
216 
217 	if (ret)
218 		pr_debug("Failed to set target on CPU:%d. ret:%d\n",
219 				cpu->cpu, ret);
220 
221 	return ret;
222 }
223 
224 static int cppc_verify_policy(struct cpufreq_policy *policy)
225 {
226 	cpufreq_verify_within_cpu_limits(policy);
227 	return 0;
228 }
229 
230 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
231 {
232 	int cpu_num = policy->cpu;
233 	struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
234 	int ret;
235 
236 	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
237 
238 	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
239 	if (ret)
240 		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
241 				cpu->perf_caps.lowest_perf, cpu_num, ret);
242 }
243 
244 /*
245  * The PCC subspace describes the rate at which platform can accept commands
246  * on the shared PCC channel (including READs which do not count towards freq
247  * trasition requests), so ideally we need to use the PCC values as a fallback
248  * if we don't have a platform specific transition_delay_us
249  */
250 #ifdef CONFIG_ARM64
251 #include <asm/cputype.h>
252 
253 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
254 {
255 	unsigned long implementor = read_cpuid_implementor();
256 	unsigned long part_num = read_cpuid_part_number();
257 	unsigned int delay_us = 0;
258 
259 	switch (implementor) {
260 	case ARM_CPU_IMP_QCOM:
261 		switch (part_num) {
262 		case QCOM_CPU_PART_FALKOR_V1:
263 		case QCOM_CPU_PART_FALKOR:
264 			delay_us = 10000;
265 			break;
266 		default:
267 			delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
268 			break;
269 		}
270 		break;
271 	default:
272 		delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
273 		break;
274 	}
275 
276 	return delay_us;
277 }
278 
279 #else
280 
281 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
282 {
283 	return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
284 }
285 #endif
286 
287 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
288 {
289 	struct cppc_cpudata *cpu;
290 	unsigned int cpu_num = policy->cpu;
291 	int ret = 0;
292 
293 	cpu = all_cpu_data[policy->cpu];
294 
295 	cpu->cpu = cpu_num;
296 	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
297 
298 	if (ret) {
299 		pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
300 				cpu_num, ret);
301 		return ret;
302 	}
303 
304 	/* Convert the lowest and nominal freq from MHz to KHz */
305 	cpu->perf_caps.lowest_freq *= 1000;
306 	cpu->perf_caps.nominal_freq *= 1000;
307 
308 	/*
309 	 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
310 	 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
311 	 */
312 	policy->min = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_nonlinear_perf);
313 	policy->max = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
314 
315 	/*
316 	 * Set cpuinfo.min_freq to Lowest to make the full range of performance
317 	 * available if userspace wants to use any perf between lowest & lowest
318 	 * nonlinear perf
319 	 */
320 	policy->cpuinfo.min_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_perf);
321 	policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
322 
323 	policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
324 	policy->shared_type = cpu->shared_type;
325 
326 	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
327 		int i;
328 
329 		cpumask_copy(policy->cpus, cpu->shared_cpu_map);
330 
331 		for_each_cpu(i, policy->cpus) {
332 			if (unlikely(i == policy->cpu))
333 				continue;
334 
335 			memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
336 			       sizeof(cpu->perf_caps));
337 		}
338 	} else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
339 		/* Support only SW_ANY for now. */
340 		pr_debug("Unsupported CPU co-ord type\n");
341 		return -EFAULT;
342 	}
343 
344 	cpu->cur_policy = policy;
345 
346 	/* Set policy->cur to max now. The governors will adjust later. */
347 	policy->cur = cppc_cpufreq_perf_to_khz(cpu,
348 					cpu->perf_caps.highest_perf);
349 	cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
350 
351 	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
352 	if (ret)
353 		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
354 				cpu->perf_caps.highest_perf, cpu_num, ret);
355 
356 	return ret;
357 }
358 
359 static inline u64 get_delta(u64 t1, u64 t0)
360 {
361 	if (t1 > t0 || t0 > ~(u32)0)
362 		return t1 - t0;
363 
364 	return (u32)t1 - (u32)t0;
365 }
366 
367 static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu,
368 				     struct cppc_perf_fb_ctrs fb_ctrs_t0,
369 				     struct cppc_perf_fb_ctrs fb_ctrs_t1)
370 {
371 	u64 delta_reference, delta_delivered;
372 	u64 reference_perf, delivered_perf;
373 
374 	reference_perf = fb_ctrs_t0.reference_perf;
375 
376 	delta_reference = get_delta(fb_ctrs_t1.reference,
377 				    fb_ctrs_t0.reference);
378 	delta_delivered = get_delta(fb_ctrs_t1.delivered,
379 				    fb_ctrs_t0.delivered);
380 
381 	/* Check to avoid divide-by zero */
382 	if (delta_reference || delta_delivered)
383 		delivered_perf = (reference_perf * delta_delivered) /
384 					delta_reference;
385 	else
386 		delivered_perf = cpu->perf_ctrls.desired_perf;
387 
388 	return cppc_cpufreq_perf_to_khz(cpu, delivered_perf);
389 }
390 
391 static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)
392 {
393 	struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
394 	struct cppc_cpudata *cpu = all_cpu_data[cpunum];
395 	int ret;
396 
397 	if (apply_hisi_workaround)
398 		return hisi_cppc_cpufreq_get_rate(cpunum);
399 
400 	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t0);
401 	if (ret)
402 		return ret;
403 
404 	udelay(2); /* 2usec delay between sampling */
405 
406 	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t1);
407 	if (ret)
408 		return ret;
409 
410 	return cppc_get_rate_from_fbctrs(cpu, fb_ctrs_t0, fb_ctrs_t1);
411 }
412 
413 static struct cpufreq_driver cppc_cpufreq_driver = {
414 	.flags = CPUFREQ_CONST_LOOPS,
415 	.verify = cppc_verify_policy,
416 	.target = cppc_cpufreq_set_target,
417 	.get = cppc_cpufreq_get_rate,
418 	.init = cppc_cpufreq_cpu_init,
419 	.stop_cpu = cppc_cpufreq_stop_cpu,
420 	.name = "cppc_cpufreq",
421 };
422 
423 static int __init cppc_cpufreq_init(void)
424 {
425 	int i, ret = 0;
426 	struct cppc_cpudata *cpu;
427 
428 	if (acpi_disabled)
429 		return -ENODEV;
430 
431 	all_cpu_data = kcalloc(num_possible_cpus(), sizeof(void *),
432 			       GFP_KERNEL);
433 	if (!all_cpu_data)
434 		return -ENOMEM;
435 
436 	for_each_possible_cpu(i) {
437 		all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
438 		if (!all_cpu_data[i])
439 			goto out;
440 
441 		cpu = all_cpu_data[i];
442 		if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
443 			goto out;
444 	}
445 
446 	ret = acpi_get_psd_map(all_cpu_data);
447 	if (ret) {
448 		pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
449 		goto out;
450 	}
451 
452 	cppc_check_hisi_workaround();
453 
454 	ret = cpufreq_register_driver(&cppc_cpufreq_driver);
455 	if (ret)
456 		goto out;
457 
458 	return ret;
459 
460 out:
461 	for_each_possible_cpu(i) {
462 		cpu = all_cpu_data[i];
463 		if (!cpu)
464 			break;
465 		free_cpumask_var(cpu->shared_cpu_map);
466 		kfree(cpu);
467 	}
468 
469 	kfree(all_cpu_data);
470 	return -ENODEV;
471 }
472 
473 static void __exit cppc_cpufreq_exit(void)
474 {
475 	struct cppc_cpudata *cpu;
476 	int i;
477 
478 	cpufreq_unregister_driver(&cppc_cpufreq_driver);
479 
480 	for_each_possible_cpu(i) {
481 		cpu = all_cpu_data[i];
482 		free_cpumask_var(cpu->shared_cpu_map);
483 		kfree(cpu);
484 	}
485 
486 	kfree(all_cpu_data);
487 }
488 
489 module_exit(cppc_cpufreq_exit);
490 MODULE_AUTHOR("Ashwin Chaugule");
491 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
492 MODULE_LICENSE("GPL");
493 
494 late_initcall(cppc_cpufreq_init);
495 
496 static const struct acpi_device_id cppc_acpi_ids[] __used = {
497 	{ACPI_PROCESSOR_DEVICE_HID, },
498 	{}
499 };
500 
501 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);
502