1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2005 Intel Corporation
4 * Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
5 * - Added _PDC for SMP C-states on Intel CPUs
6 */
7
8#include <linux/kernel.h>
9#include <linux/export.h>
10#include <linux/init.h>
11#include <linux/acpi.h>
12#include <linux/cpu.h>
13#include <linux/sched.h>
14
15#include <acpi/processor.h>
16#include <asm/cpu_device_id.h>
17#include <asm/cpuid/api.h>
18#include <asm/mwait.h>
19#include <asm/special_insns.h>
20#include <asm/smp.h>
21
22/*
23 * Initialize bm_flags based on the CPU cache properties
24 * On SMP it depends on cache configuration
25 * - When cache is not shared among all CPUs, we flush cache
26 * before entering C3.
27 * - When cache is shared among all CPUs, we use bm_check
28 * mechanism as in UP case
29 *
30 * This routine is called only after all the CPUs are online
31 */
32void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
33 unsigned int cpu)
34{
35 struct cpuinfo_x86 *c = &cpu_data(cpu);
36
37 flags->bm_check = 0;
38 if (num_online_cpus() == 1)
39 flags->bm_check = 1;
40 else if (c->x86_vendor == X86_VENDOR_INTEL) {
41 /*
42 * Today all MP CPUs that support C3 share cache.
43 * And caches should not be flushed by software while
44 * entering C3 type state.
45 */
46 flags->bm_check = 1;
47 }
48
49 /*
50 * On all recent Intel platforms, ARB_DISABLE is a nop.
51 * So, set bm_control to zero to indicate that ARB_DISABLE
52 * is not required while entering C3 type state.
53 */
54 if (c->x86_vendor == X86_VENDOR_INTEL &&
55 (c->x86 > 15 || (c->x86_vfm >= INTEL_CORE2_MEROM && c->x86_vfm <= INTEL_FAM6_LAST)))
56 flags->bm_control = 0;
57
58 if (c->x86_vendor == X86_VENDOR_CENTAUR) {
59 if (c->x86 > 6 || (c->x86 == 6 && c->x86_model == 0x0f &&
60 c->x86_stepping >= 0x0e)) {
61 /*
62 * For all recent Centaur CPUs, the ucode will make sure that each
63 * core can keep cache coherence with each other while entering C3
64 * type state. So, set bm_check to 1 to indicate that the kernel
65 * doesn't need to execute a cache flush operation (WBINVD) when
66 * entering C3 type state.
67 */
68 flags->bm_check = 1;
69 /*
70 * For all recent Centaur platforms, ARB_DISABLE is a nop.
71 * Set bm_control to zero to indicate that ARB_DISABLE is
72 * not required while entering C3 type state.
73 */
74 flags->bm_control = 0;
75 }
76 }
77
78 if (c->x86_vendor == X86_VENDOR_ZHAOXIN) {
79 /*
80 * All Zhaoxin CPUs that support C3 share cache.
81 * And caches should not be flushed by software while
82 * entering C3 type state.
83 */
84 flags->bm_check = 1;
85 /*
86 * On all recent Zhaoxin platforms, ARB_DISABLE is a nop.
87 * So, set bm_control to zero to indicate that ARB_DISABLE
88 * is not required while entering C3 type state.
89 */
90 flags->bm_control = 0;
91 }
92 if (cpu_feature_enabled(X86_FEATURE_ZEN)) {
93 /*
94 * For all AMD Zen or newer CPUs that support C3, caches
95 * should not be flushed by software while entering C3
96 * type state. Set bm->check to 1 so that kernel doesn't
97 * need to execute cache flush operation.
98 */
99 flags->bm_check = 1;
100 /*
101 * In current AMD C state implementation ARB_DIS is no longer
102 * used. So set bm_control to zero to indicate ARB_DIS is not
103 * required while entering C3 type state.
104 */
105 flags->bm_control = 0;
106 }
107}
108EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
109
110/* The code below handles cstate entry with monitor-mwait pair on Intel*/
111
112struct cstate_entry {
113 struct {
114 unsigned int eax;
115 unsigned int ecx;
116 } states[ACPI_PROCESSOR_MAX_POWER];
117};
118static struct cstate_entry __percpu *cpu_cstate_entry; /* per CPU ptr */
119
120static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
121
122#define NATIVE_CSTATE_BEYOND_HALT (2)
123
124static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
125{
126 struct acpi_processor_cx *cx = _cx;
127 long retval;
128 unsigned int eax, ebx, ecx, edx;
129 unsigned int edx_part;
130 unsigned int cstate_type; /* C-state type and not ACPI C-state type */
131 unsigned int num_cstate_subtype;
132
133 cpuid(CPUID_LEAF_MWAIT, eax: &eax, ebx: &ebx, ecx: &ecx, edx: &edx);
134
135 /* Check whether this particular cx_type (in CST) is supported or not */
136 cstate_type = (((cx->address >> MWAIT_SUBSTATE_SIZE) &
137 MWAIT_CSTATE_MASK) + 1) & MWAIT_CSTATE_MASK;
138 edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
139 num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
140
141 retval = 0;
142 /* If the HW does not support any sub-states in this C-state */
143 if (num_cstate_subtype == 0) {
144 pr_warn(FW_BUG "ACPI MWAIT C-state 0x%x not supported by HW (0x%x)\n",
145 cx->address, edx_part);
146 retval = -1;
147 goto out;
148 }
149
150 /* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
151 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
152 !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
153 retval = -1;
154 goto out;
155 }
156
157 if (!mwait_supported[cstate_type]) {
158 mwait_supported[cstate_type] = 1;
159 printk(KERN_DEBUG
160 "Monitor-Mwait will be used to enter C-%d state\n",
161 cx->type);
162 }
163 snprintf(buf: cx->desc,
164 ACPI_CX_DESC_LEN, fmt: "ACPI FFH MWAIT 0x%x",
165 cx->address);
166out:
167 return retval;
168}
169
170int acpi_processor_ffh_cstate_probe(unsigned int cpu,
171 struct acpi_processor_cx *cx, struct acpi_power_register *reg)
172{
173 struct cstate_entry *percpu_entry;
174 struct cpuinfo_x86 *c = &cpu_data(cpu);
175 long retval;
176
177 if (!cpu_cstate_entry || c->cpuid_level < CPUID_LEAF_MWAIT)
178 return -1;
179
180 if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
181 return -1;
182
183 percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
184 percpu_entry->states[cx->index].eax = 0;
185 percpu_entry->states[cx->index].ecx = 0;
186
187 /* Make sure we are running on right CPU */
188
189 retval = call_on_cpu(cpu, fn: acpi_processor_ffh_cstate_probe_cpu, arg: cx,
190 direct: false);
191 if (retval == 0) {
192 /* Use the hint in CST */
193 percpu_entry->states[cx->index].eax = cx->address;
194 percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
195 }
196
197 /*
198 * For _CST FFH on Intel, if GAS.access_size bit 1 is cleared,
199 * then we should skip checking BM_STS for this C-state.
200 * ref: "Intel Processor Vendor-Specific ACPI Interface Specification"
201 */
202 if ((c->x86_vendor == X86_VENDOR_INTEL) && !(reg->access_size & 0x2))
203 cx->bm_sts_skip = 1;
204
205 return retval;
206}
207EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
208
209void __noreturn acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
210{
211 unsigned int cpu = smp_processor_id();
212 struct cstate_entry *percpu_entry;
213
214 percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
215 mwait_play_dead(eax_hint: percpu_entry->states[cx->index].eax);
216}
217EXPORT_SYMBOL_GPL(acpi_processor_ffh_play_dead);
218
219void __cpuidle acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
220{
221 unsigned int cpu = smp_processor_id();
222 struct cstate_entry *percpu_entry;
223
224 percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
225 mwait_idle_with_hints(eax: percpu_entry->states[cx->index].eax,
226 ecx: percpu_entry->states[cx->index].ecx);
227}
228EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);
229
230static int __init ffh_cstate_init(void)
231{
232 struct cpuinfo_x86 *c = &boot_cpu_data;
233
234 if (c->x86_vendor != X86_VENDOR_INTEL &&
235 c->x86_vendor != X86_VENDOR_AMD &&
236 c->x86_vendor != X86_VENDOR_HYGON)
237 return -1;
238
239 cpu_cstate_entry = alloc_percpu(struct cstate_entry);
240 return 0;
241}
242
243static void __exit ffh_cstate_exit(void)
244{
245 free_percpu(pdata: cpu_cstate_entry);
246 cpu_cstate_entry = NULL;
247}
248
249arch_initcall(ffh_cstate_init);
250__exitcall(ffh_cstate_exit);
251

source code of linux/arch/x86/kernel/acpi/cstate.c