xref: /openbmc/linux/arch/x86/kernel/acpi/cppc.c (revision fa797951)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * cppc.c: CPPC Interface for x86
4  * Copyright (c) 2016, Intel Corporation.
5  */
6 
7 #include <acpi/cppc_acpi.h>
8 #include <asm/msr.h>
9 #include <asm/processor.h>
10 #include <asm/topology.h>
11 
12 /* Refer to drivers/acpi/cppc_acpi.c for the description of functions */
13 
cpc_supported_by_cpu(void)14 bool cpc_supported_by_cpu(void)
15 {
16 	switch (boot_cpu_data.x86_vendor) {
17 	case X86_VENDOR_AMD:
18 	case X86_VENDOR_HYGON:
19 		if (boot_cpu_data.x86 == 0x19 && ((boot_cpu_data.x86_model <= 0x0f) ||
20 		    (boot_cpu_data.x86_model >= 0x20 && boot_cpu_data.x86_model <= 0x2f)))
21 			return true;
22 		else if (boot_cpu_data.x86 == 0x17 &&
23 			 boot_cpu_data.x86_model >= 0x30 && boot_cpu_data.x86_model <= 0x7f)
24 			return true;
25 		return boot_cpu_has(X86_FEATURE_CPPC);
26 	}
27 	return false;
28 }
29 
cpc_ffh_supported(void)30 bool cpc_ffh_supported(void)
31 {
32 	return true;
33 }
34 
cpc_read_ffh(int cpunum,struct cpc_reg * reg,u64 * val)35 int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
36 {
37 	int err;
38 
39 	err = rdmsrl_safe_on_cpu(cpunum, reg->address, val);
40 	if (!err) {
41 		u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
42 				       reg->bit_offset);
43 
44 		*val &= mask;
45 		*val >>= reg->bit_offset;
46 	}
47 	return err;
48 }
49 
cpc_write_ffh(int cpunum,struct cpc_reg * reg,u64 val)50 int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
51 {
52 	u64 rd_val;
53 	int err;
54 
55 	err = rdmsrl_safe_on_cpu(cpunum, reg->address, &rd_val);
56 	if (!err) {
57 		u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
58 				       reg->bit_offset);
59 
60 		val <<= reg->bit_offset;
61 		val &= mask;
62 		rd_val &= ~mask;
63 		rd_val |= val;
64 		err = wrmsrl_safe_on_cpu(cpunum, reg->address, rd_val);
65 	}
66 	return err;
67 }
68 
amd_set_max_freq_ratio(void)69 static void amd_set_max_freq_ratio(void)
70 {
71 	struct cppc_perf_caps perf_caps;
72 	u64 highest_perf, nominal_perf;
73 	u64 perf_ratio;
74 	int rc;
75 
76 	rc = cppc_get_perf_caps(0, &perf_caps);
77 	if (rc) {
78 		pr_debug("Could not retrieve perf counters (%d)\n", rc);
79 		return;
80 	}
81 
82 	highest_perf = amd_get_highest_perf();
83 	nominal_perf = perf_caps.nominal_perf;
84 
85 	if (!highest_perf || !nominal_perf) {
86 		pr_debug("Could not retrieve highest or nominal performance\n");
87 		return;
88 	}
89 
90 	perf_ratio = div_u64(highest_perf * SCHED_CAPACITY_SCALE, nominal_perf);
91 	/* midpoint between max_boost and max_P */
92 	perf_ratio = (perf_ratio + SCHED_CAPACITY_SCALE) >> 1;
93 	if (!perf_ratio) {
94 		pr_debug("Non-zero highest/nominal perf values led to a 0 ratio\n");
95 		return;
96 	}
97 
98 	freq_invariance_set_perf_ratio(perf_ratio, false);
99 }
100 
101 static DEFINE_MUTEX(freq_invariance_lock);
102 
init_freq_invariance_cppc(void)103 void init_freq_invariance_cppc(void)
104 {
105 	static bool init_done;
106 
107 	if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
108 		return;
109 
110 	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
111 		return;
112 
113 	mutex_lock(&freq_invariance_lock);
114 	if (!init_done)
115 		amd_set_max_freq_ratio();
116 	init_done = true;
117 	mutex_unlock(&freq_invariance_lock);
118 }
119