1/*
2 * arch/arm64/kernel/topology.c
3 *
4 * Copyright (C) 2011,2013,2014 Linaro Limited.
5 *
6 * Based on the arm32 version written by Vincent Guittot in turn based on
7 * arch/sh/kernel/topology.c
8 *
9 * This file is subject to the terms and conditions of the GNU General Public
10 * License. See the file "COPYING" in the main directory of this archive
11 * for more details.
12 */
13
14#include <linux/acpi.h>
15#include <linux/arch_topology.h>
16#include <linux/cacheinfo.h>
17#include <linux/cpufreq.h>
18#include <linux/init.h>
19#include <linux/percpu.h>
20
21#include <asm/cpu.h>
22#include <asm/cputype.h>
23#include <asm/topology.h>
24
25#ifdef CONFIG_ACPI
26static bool __init acpi_cpu_is_threaded(int cpu)
27{
28 int is_threaded = acpi_pptt_cpu_is_thread(cpu);
29
30 /*
31 * if the PPTT doesn't have thread information, assume a homogeneous
32 * machine and return the current CPU's thread state.
33 */
34 if (is_threaded < 0)
35 is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
36
37 return !!is_threaded;
38}
39
40/*
41 * Propagate the topology information of the processor_topology_node tree to the
42 * cpu_topology array.
43 */
44int __init parse_acpi_topology(void)
45{
46 int cpu, topology_id;
47
48 if (acpi_disabled)
49 return 0;
50
51 for_each_possible_cpu(cpu) {
52 topology_id = find_acpi_cpu_topology(cpu, level: 0);
53 if (topology_id < 0)
54 return topology_id;
55
56 if (acpi_cpu_is_threaded(cpu)) {
57 cpu_topology[cpu].thread_id = topology_id;
58 topology_id = find_acpi_cpu_topology(cpu, level: 1);
59 cpu_topology[cpu].core_id = topology_id;
60 } else {
61 cpu_topology[cpu].thread_id = -1;
62 cpu_topology[cpu].core_id = topology_id;
63 }
64 topology_id = find_acpi_cpu_topology_cluster(cpu);
65 cpu_topology[cpu].cluster_id = topology_id;
66 topology_id = find_acpi_cpu_topology_package(cpu);
67 cpu_topology[cpu].package_id = topology_id;
68 }
69
70 return 0;
71}
72#endif
73
74#ifdef CONFIG_ARM64_AMU_EXTN
75#define read_corecnt() read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0)
76#define read_constcnt() read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0)
77#else
78#define read_corecnt() (0UL)
79#define read_constcnt() (0UL)
80#endif
81
82#undef pr_fmt
83#define pr_fmt(fmt) "AMU: " fmt
84
85/*
86 * Ensure that amu_scale_freq_tick() will return SCHED_CAPACITY_SCALE until
87 * the CPU capacity and its associated frequency have been correctly
88 * initialized.
89 */
90static DEFINE_PER_CPU_READ_MOSTLY(unsigned long, arch_max_freq_scale) = 1UL << (2 * SCHED_CAPACITY_SHIFT);
91static DEFINE_PER_CPU(u64, arch_const_cycles_prev);
92static DEFINE_PER_CPU(u64, arch_core_cycles_prev);
93static cpumask_var_t amu_fie_cpus;
94
95void update_freq_counters_refs(void)
96{
97 this_cpu_write(arch_core_cycles_prev, read_corecnt());
98 this_cpu_write(arch_const_cycles_prev, read_constcnt());
99}
100
101static inline bool freq_counters_valid(int cpu)
102{
103 if ((cpu >= nr_cpu_ids) || !cpumask_test_cpu(cpu, cpu_present_mask))
104 return false;
105
106 if (!cpu_has_amu_feat(cpu)) {
107 pr_debug("CPU%d: counters are not supported.\n", cpu);
108 return false;
109 }
110
111 if (unlikely(!per_cpu(arch_const_cycles_prev, cpu) ||
112 !per_cpu(arch_core_cycles_prev, cpu))) {
113 pr_debug("CPU%d: cycle counters are not enabled.\n", cpu);
114 return false;
115 }
116
117 return true;
118}
119
120void freq_inv_set_max_ratio(int cpu, u64 max_rate)
121{
122 u64 ratio, ref_rate = arch_timer_get_rate();
123
124 if (unlikely(!max_rate || !ref_rate)) {
125 WARN_ONCE(1, "CPU%d: invalid maximum or reference frequency.\n",
126 cpu);
127 return;
128 }
129
130 /*
131 * Pre-compute the fixed ratio between the frequency of the constant
132 * reference counter and the maximum frequency of the CPU.
133 *
134 * ref_rate
135 * arch_max_freq_scale = ---------- * SCHED_CAPACITY_SCALE²
136 * max_rate
137 *
138 * We use a factor of 2 * SCHED_CAPACITY_SHIFT -> SCHED_CAPACITY_SCALE²
139 * in order to ensure a good resolution for arch_max_freq_scale for
140 * very low reference frequencies (down to the KHz range which should
141 * be unlikely).
142 */
143 ratio = ref_rate << (2 * SCHED_CAPACITY_SHIFT);
144 ratio = div64_u64(dividend: ratio, divisor: max_rate);
145 if (!ratio) {
146 WARN_ONCE(1, "Reference frequency too low.\n");
147 return;
148 }
149
150 WRITE_ONCE(per_cpu(arch_max_freq_scale, cpu), (unsigned long)ratio);
151}
152
153static void amu_scale_freq_tick(void)
154{
155 u64 prev_core_cnt, prev_const_cnt;
156 u64 core_cnt, const_cnt, scale;
157
158 prev_const_cnt = this_cpu_read(arch_const_cycles_prev);
159 prev_core_cnt = this_cpu_read(arch_core_cycles_prev);
160
161 update_freq_counters_refs();
162
163 const_cnt = this_cpu_read(arch_const_cycles_prev);
164 core_cnt = this_cpu_read(arch_core_cycles_prev);
165
166 if (unlikely(core_cnt <= prev_core_cnt ||
167 const_cnt <= prev_const_cnt))
168 return;
169
170 /*
171 * /\core arch_max_freq_scale
172 * scale = ------- * --------------------
173 * /\const SCHED_CAPACITY_SCALE
174 *
175 * See validate_cpu_freq_invariance_counters() for details on
176 * arch_max_freq_scale and the use of SCHED_CAPACITY_SHIFT.
177 */
178 scale = core_cnt - prev_core_cnt;
179 scale *= this_cpu_read(arch_max_freq_scale);
180 scale = div64_u64(dividend: scale >> SCHED_CAPACITY_SHIFT,
181 divisor: const_cnt - prev_const_cnt);
182
183 scale = min_t(unsigned long, scale, SCHED_CAPACITY_SCALE);
184 this_cpu_write(arch_freq_scale, (unsigned long)scale);
185}
186
187static struct scale_freq_data amu_sfd = {
188 .source = SCALE_FREQ_SOURCE_ARCH,
189 .set_freq_scale = amu_scale_freq_tick,
190};
191
192static void amu_fie_setup(const struct cpumask *cpus)
193{
194 int cpu;
195
196 /* We are already set since the last insmod of cpufreq driver */
197 if (unlikely(cpumask_subset(cpus, amu_fie_cpus)))
198 return;
199
200 for_each_cpu(cpu, cpus) {
201 if (!freq_counters_valid(cpu))
202 return;
203 }
204
205 cpumask_or(dstp: amu_fie_cpus, src1p: amu_fie_cpus, src2p: cpus);
206
207 topology_set_scale_freq_source(data: &amu_sfd, cpus: amu_fie_cpus);
208
209 pr_debug("CPUs[%*pbl]: counters will be used for FIE.",
210 cpumask_pr_args(cpus));
211}
212
213static int init_amu_fie_callback(struct notifier_block *nb, unsigned long val,
214 void *data)
215{
216 struct cpufreq_policy *policy = data;
217
218 if (val == CPUFREQ_CREATE_POLICY)
219 amu_fie_setup(cpus: policy->related_cpus);
220
221 /*
222 * We don't need to handle CPUFREQ_REMOVE_POLICY event as the AMU
223 * counters don't have any dependency on cpufreq driver once we have
224 * initialized AMU support and enabled invariance. The AMU counters will
225 * keep on working just fine in the absence of the cpufreq driver, and
226 * for the CPUs for which there are no counters available, the last set
227 * value of arch_freq_scale will remain valid as that is the frequency
228 * those CPUs are running at.
229 */
230
231 return 0;
232}
233
234static struct notifier_block init_amu_fie_notifier = {
235 .notifier_call = init_amu_fie_callback,
236};
237
238static int __init init_amu_fie(void)
239{
240 int ret;
241
242 if (!zalloc_cpumask_var(mask: &amu_fie_cpus, GFP_KERNEL))
243 return -ENOMEM;
244
245 ret = cpufreq_register_notifier(nb: &init_amu_fie_notifier,
246 CPUFREQ_POLICY_NOTIFIER);
247 if (ret)
248 free_cpumask_var(mask: amu_fie_cpus);
249
250 return ret;
251}
252core_initcall(init_amu_fie);
253
254#ifdef CONFIG_ACPI_CPPC_LIB
255#include <acpi/cppc_acpi.h>
256
257static void cpu_read_corecnt(void *val)
258{
259 /*
260 * A value of 0 can be returned if the current CPU does not support AMUs
261 * or if the counter is disabled for this CPU. A return value of 0 at
262 * counter read is properly handled as an error case by the users of the
263 * counter.
264 */
265 *(u64 *)val = read_corecnt();
266}
267
268static void cpu_read_constcnt(void *val)
269{
270 /*
271 * Return 0 if the current CPU is affected by erratum 2457168. A value
272 * of 0 is also returned if the current CPU does not support AMUs or if
273 * the counter is disabled. A return value of 0 at counter read is
274 * properly handled as an error case by the users of the counter.
275 */
276 *(u64 *)val = this_cpu_has_cap(ARM64_WORKAROUND_2457168) ?
277 0UL : read_constcnt();
278}
279
280static inline
281int counters_read_on_cpu(int cpu, smp_call_func_t func, u64 *val)
282{
283 /*
284 * Abort call on counterless CPU or when interrupts are
285 * disabled - can lead to deadlock in smp sync call.
286 */
287 if (!cpu_has_amu_feat(cpu))
288 return -EOPNOTSUPP;
289
290 if (WARN_ON_ONCE(irqs_disabled()))
291 return -EPERM;
292
293 smp_call_function_single(cpuid: cpu, func, info: val, wait: 1);
294
295 return 0;
296}
297
298/*
299 * Refer to drivers/acpi/cppc_acpi.c for the description of the functions
300 * below.
301 */
302bool cpc_ffh_supported(void)
303{
304 int cpu = get_cpu_with_amu_feat();
305
306 /*
307 * FFH is considered supported if there is at least one present CPU that
308 * supports AMUs. Using FFH to read core and reference counters for CPUs
309 * that do not support AMUs, have counters disabled or that are affected
310 * by errata, will result in a return value of 0.
311 *
312 * This is done to allow any enabled and valid counters to be read
313 * through FFH, knowing that potentially returning 0 as counter value is
314 * properly handled by the users of these counters.
315 */
316 if ((cpu >= nr_cpu_ids) || !cpumask_test_cpu(cpu, cpu_present_mask))
317 return false;
318
319 return true;
320}
321
322int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val)
323{
324 int ret = -EOPNOTSUPP;
325
326 switch ((u64)reg->address) {
327 case 0x0:
328 ret = counters_read_on_cpu(cpu, func: cpu_read_corecnt, val);
329 break;
330 case 0x1:
331 ret = counters_read_on_cpu(cpu, func: cpu_read_constcnt, val);
332 break;
333 }
334
335 if (!ret) {
336 *val &= GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
337 reg->bit_offset);
338 *val >>= reg->bit_offset;
339 }
340
341 return ret;
342}
343
344int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
345{
346 return -EOPNOTSUPP;
347}
348#endif /* CONFIG_ACPI_CPPC_LIB */
349

source code of linux/arch/arm64/kernel/topology.c