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 /* Callback function used to retrieve the max frequency from DMI */
46 static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
47 {
48 	const u8 *dmi_data = (const u8 *)dm;
49 	u16 *mhz = (u16 *)private;
50 
51 	if (dm->type == DMI_ENTRY_PROCESSOR &&
52 	    dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
53 		u16 val = (u16)get_unaligned((const u16 *)
54 				(dmi_data + DMI_PROCESSOR_MAX_SPEED));
55 		*mhz = val > *mhz ? val : *mhz;
56 	}
57 }
58 
59 /* Look up the max frequency in DMI */
60 static u64 cppc_get_dmi_max_khz(void)
61 {
62 	u16 mhz = 0;
63 
64 	dmi_walk(cppc_find_dmi_mhz, &mhz);
65 
66 	/*
67 	 * Real stupid fallback value, just in case there is no
68 	 * actual value set.
69 	 */
70 	mhz = mhz ? mhz : 1;
71 
72 	return (1000 * mhz);
73 }
74 
75 /*
76  * If CPPC lowest_freq and nominal_freq registers are exposed then we can
77  * use them to convert perf to freq and vice versa
78  *
79  * If the perf/freq point lies between Nominal and Lowest, we can treat
80  * (Low perf, Low freq) and (Nom Perf, Nom freq) as 2D co-ordinates of a line
81  * and extrapolate the rest
82  * For perf/freq > Nominal, we use the ratio perf:freq at Nominal for conversion
83  */
84 static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu,
85 					unsigned int perf)
86 {
87 	static u64 max_khz;
88 	struct cppc_perf_caps *caps = &cpu->perf_caps;
89 	u64 mul, div;
90 
91 	if (caps->lowest_freq && caps->nominal_freq) {
92 		if (perf >= caps->nominal_perf) {
93 			mul = caps->nominal_freq;
94 			div = caps->nominal_perf;
95 		} else {
96 			mul = caps->nominal_freq - caps->lowest_freq;
97 			div = caps->nominal_perf - caps->lowest_perf;
98 		}
99 	} else {
100 		if (!max_khz)
101 			max_khz = cppc_get_dmi_max_khz();
102 		mul = max_khz;
103 		div = cpu->perf_caps.highest_perf;
104 	}
105 	return (u64)perf * mul / div;
106 }
107 
108 static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu,
109 					unsigned int freq)
110 {
111 	static u64 max_khz;
112 	struct cppc_perf_caps *caps = &cpu->perf_caps;
113 	u64  mul, div;
114 
115 	if (caps->lowest_freq && caps->nominal_freq) {
116 		if (freq >= caps->nominal_freq) {
117 			mul = caps->nominal_perf;
118 			div = caps->nominal_freq;
119 		} else {
120 			mul = caps->lowest_perf;
121 			div = caps->lowest_freq;
122 		}
123 	} else {
124 		if (!max_khz)
125 			max_khz = cppc_get_dmi_max_khz();
126 		mul = cpu->perf_caps.highest_perf;
127 		div = max_khz;
128 	}
129 
130 	return (u64)freq * mul / div;
131 }
132 
133 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
134 		unsigned int target_freq,
135 		unsigned int relation)
136 {
137 	struct cppc_cpudata *cpu;
138 	struct cpufreq_freqs freqs;
139 	u32 desired_perf;
140 	int ret = 0;
141 
142 	cpu = all_cpu_data[policy->cpu];
143 
144 	desired_perf = cppc_cpufreq_khz_to_perf(cpu, target_freq);
145 	/* Return if it is exactly the same perf */
146 	if (desired_perf == cpu->perf_ctrls.desired_perf)
147 		return ret;
148 
149 	cpu->perf_ctrls.desired_perf = desired_perf;
150 	freqs.old = policy->cur;
151 	freqs.new = target_freq;
152 
153 	cpufreq_freq_transition_begin(policy, &freqs);
154 	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
155 	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
156 
157 	if (ret)
158 		pr_debug("Failed to set target on CPU:%d. ret:%d\n",
159 				cpu->cpu, ret);
160 
161 	return ret;
162 }
163 
164 static int cppc_verify_policy(struct cpufreq_policy *policy)
165 {
166 	cpufreq_verify_within_cpu_limits(policy);
167 	return 0;
168 }
169 
170 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
171 {
172 	int cpu_num = policy->cpu;
173 	struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
174 	int ret;
175 
176 	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
177 
178 	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
179 	if (ret)
180 		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
181 				cpu->perf_caps.lowest_perf, cpu_num, ret);
182 }
183 
184 /*
185  * The PCC subspace describes the rate at which platform can accept commands
186  * on the shared PCC channel (including READs which do not count towards freq
187  * trasition requests), so ideally we need to use the PCC values as a fallback
188  * if we don't have a platform specific transition_delay_us
189  */
190 #ifdef CONFIG_ARM64
191 #include <asm/cputype.h>
192 
193 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
194 {
195 	unsigned long implementor = read_cpuid_implementor();
196 	unsigned long part_num = read_cpuid_part_number();
197 	unsigned int delay_us = 0;
198 
199 	switch (implementor) {
200 	case ARM_CPU_IMP_QCOM:
201 		switch (part_num) {
202 		case QCOM_CPU_PART_FALKOR_V1:
203 		case QCOM_CPU_PART_FALKOR:
204 			delay_us = 10000;
205 			break;
206 		default:
207 			delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
208 			break;
209 		}
210 		break;
211 	default:
212 		delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
213 		break;
214 	}
215 
216 	return delay_us;
217 }
218 
219 #else
220 
221 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
222 {
223 	return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
224 }
225 #endif
226 
227 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
228 {
229 	struct cppc_cpudata *cpu;
230 	unsigned int cpu_num = policy->cpu;
231 	int ret = 0;
232 
233 	cpu = all_cpu_data[policy->cpu];
234 
235 	cpu->cpu = cpu_num;
236 	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
237 
238 	if (ret) {
239 		pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
240 				cpu_num, ret);
241 		return ret;
242 	}
243 
244 	/* Convert the lowest and nominal freq from MHz to KHz */
245 	cpu->perf_caps.lowest_freq *= 1000;
246 	cpu->perf_caps.nominal_freq *= 1000;
247 
248 	/*
249 	 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
250 	 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
251 	 */
252 	policy->min = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_nonlinear_perf);
253 	policy->max = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
254 
255 	/*
256 	 * Set cpuinfo.min_freq to Lowest to make the full range of performance
257 	 * available if userspace wants to use any perf between lowest & lowest
258 	 * nonlinear perf
259 	 */
260 	policy->cpuinfo.min_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_perf);
261 	policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
262 
263 	policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
264 	policy->shared_type = cpu->shared_type;
265 
266 	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
267 		int i;
268 
269 		cpumask_copy(policy->cpus, cpu->shared_cpu_map);
270 
271 		for_each_cpu(i, policy->cpus) {
272 			if (unlikely(i == policy->cpu))
273 				continue;
274 
275 			memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
276 			       sizeof(cpu->perf_caps));
277 		}
278 	} else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
279 		/* Support only SW_ANY for now. */
280 		pr_debug("Unsupported CPU co-ord type\n");
281 		return -EFAULT;
282 	}
283 
284 	cpu->cur_policy = policy;
285 
286 	/* Set policy->cur to max now. The governors will adjust later. */
287 	policy->cur = cppc_cpufreq_perf_to_khz(cpu,
288 					cpu->perf_caps.highest_perf);
289 	cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
290 
291 	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
292 	if (ret)
293 		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
294 				cpu->perf_caps.highest_perf, cpu_num, ret);
295 
296 	return ret;
297 }
298 
299 static inline u64 get_delta(u64 t1, u64 t0)
300 {
301 	if (t1 > t0 || t0 > ~(u32)0)
302 		return t1 - t0;
303 
304 	return (u32)t1 - (u32)t0;
305 }
306 
307 static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu,
308 				     struct cppc_perf_fb_ctrs fb_ctrs_t0,
309 				     struct cppc_perf_fb_ctrs fb_ctrs_t1)
310 {
311 	u64 delta_reference, delta_delivered;
312 	u64 reference_perf, delivered_perf;
313 
314 	reference_perf = fb_ctrs_t0.reference_perf;
315 
316 	delta_reference = get_delta(fb_ctrs_t1.reference,
317 				    fb_ctrs_t0.reference);
318 	delta_delivered = get_delta(fb_ctrs_t1.delivered,
319 				    fb_ctrs_t0.delivered);
320 
321 	/* Check to avoid divide-by zero */
322 	if (delta_reference || delta_delivered)
323 		delivered_perf = (reference_perf * delta_delivered) /
324 					delta_reference;
325 	else
326 		delivered_perf = cpu->perf_ctrls.desired_perf;
327 
328 	return cppc_cpufreq_perf_to_khz(cpu, delivered_perf);
329 }
330 
331 static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)
332 {
333 	struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
334 	struct cppc_cpudata *cpu = all_cpu_data[cpunum];
335 	int ret;
336 
337 	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t0);
338 	if (ret)
339 		return ret;
340 
341 	udelay(2); /* 2usec delay between sampling */
342 
343 	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t1);
344 	if (ret)
345 		return ret;
346 
347 	return cppc_get_rate_from_fbctrs(cpu, fb_ctrs_t0, fb_ctrs_t1);
348 }
349 
350 static struct cpufreq_driver cppc_cpufreq_driver = {
351 	.flags = CPUFREQ_CONST_LOOPS,
352 	.verify = cppc_verify_policy,
353 	.target = cppc_cpufreq_set_target,
354 	.get = cppc_cpufreq_get_rate,
355 	.init = cppc_cpufreq_cpu_init,
356 	.stop_cpu = cppc_cpufreq_stop_cpu,
357 	.name = "cppc_cpufreq",
358 };
359 
360 static int __init cppc_cpufreq_init(void)
361 {
362 	int i, ret = 0;
363 	struct cppc_cpudata *cpu;
364 
365 	if (acpi_disabled)
366 		return -ENODEV;
367 
368 	all_cpu_data = kcalloc(num_possible_cpus(), sizeof(void *),
369 			       GFP_KERNEL);
370 	if (!all_cpu_data)
371 		return -ENOMEM;
372 
373 	for_each_possible_cpu(i) {
374 		all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
375 		if (!all_cpu_data[i])
376 			goto out;
377 
378 		cpu = all_cpu_data[i];
379 		if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
380 			goto out;
381 	}
382 
383 	ret = acpi_get_psd_map(all_cpu_data);
384 	if (ret) {
385 		pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
386 		goto out;
387 	}
388 
389 	ret = cpufreq_register_driver(&cppc_cpufreq_driver);
390 	if (ret)
391 		goto out;
392 
393 	return ret;
394 
395 out:
396 	for_each_possible_cpu(i) {
397 		cpu = all_cpu_data[i];
398 		if (!cpu)
399 			break;
400 		free_cpumask_var(cpu->shared_cpu_map);
401 		kfree(cpu);
402 	}
403 
404 	kfree(all_cpu_data);
405 	return -ENODEV;
406 }
407 
408 static void __exit cppc_cpufreq_exit(void)
409 {
410 	struct cppc_cpudata *cpu;
411 	int i;
412 
413 	cpufreq_unregister_driver(&cppc_cpufreq_driver);
414 
415 	for_each_possible_cpu(i) {
416 		cpu = all_cpu_data[i];
417 		free_cpumask_var(cpu->shared_cpu_map);
418 		kfree(cpu);
419 	}
420 
421 	kfree(all_cpu_data);
422 }
423 
424 module_exit(cppc_cpufreq_exit);
425 MODULE_AUTHOR("Ashwin Chaugule");
426 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
427 MODULE_LICENSE("GPL");
428 
429 late_initcall(cppc_cpufreq_init);
430 
431 static const struct acpi_device_id cppc_acpi_ids[] __used = {
432 	{ACPI_PROCESSOR_DEVICE_HID, },
433 	{}
434 };
435 
436 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);
437