[PATCH 2/8] x86/amd: Rename amd_get_highest_perf() to amd_get_boost_ratio_numerator()

[Mario Limonciello <superm1@kernel.org>]

From: Mario Limonciello <mario.limonciello@amd.com>

The function name is ambiguous because it returns an intermediate value
for calculating maximum frequency rather than the CPPC 'Highest Perf'
register.

Rename the function to clarify its use and allow the function to return
errors. Adjust the consumer in acpi-cpufreq to catch errors.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 arch/x86/include/asm/processor.h |  3 ---
 arch/x86/kernel/acpi/cppc.c      | 38 +++++++++++++++++++++++---------
 drivers/cpufreq/acpi-cpufreq.c   | 12 +++++++---
 include/acpi/cppc_acpi.h         |  6 +++++
 4 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index a75a07f4931fd..775acbdea1a96 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -691,8 +691,6 @@ static inline u32 per_cpu_l2c_id(unsigned int cpu)
 }
 
 #ifdef CONFIG_CPU_SUP_AMD
-extern u32 amd_get_highest_perf(void);
-
 /*
  * Issue a DIV 0/1 insn to clear any division data from previous DIV
  * operations.
@@ -705,7 +703,6 @@ static __always_inline void amd_clear_divider(void)
 
 extern void amd_check_microcode(void);
 #else
-static inline u32 amd_get_highest_perf(void)		{ return 0; }
 static inline void amd_clear_divider(void)		{ }
 static inline void amd_check_microcode(void)		{ }
 #endif
diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
index 7ec8f2ce859c8..1d631ac5ec328 100644
--- a/arch/x86/kernel/acpi/cppc.c
+++ b/arch/x86/kernel/acpi/cppc.c
@@ -79,11 +79,13 @@ static void amd_set_max_freq_ratio(void)
 		return;
 	}
 
-	highest_perf = amd_get_highest_perf();
+	rc = amd_get_boost_ratio_numerator(0, &highest_perf);
+	if (rc)
+		pr_debug("Could not retrieve highest performance\n");
 	nominal_perf = perf_caps.nominal_perf;
 
-	if (!highest_perf || !nominal_perf) {
-		pr_debug("Could not retrieve highest or nominal performance\n");
+	if (!nominal_perf) {
+		pr_debug("Could not retrieve nominal performance\n");
 		return;
 	}
 
@@ -117,18 +119,34 @@ void init_freq_invariance_cppc(void)
 	mutex_unlock(&freq_invariance_lock);
 }
 
-u32 amd_get_highest_perf(void)
+/**
+ * amd_get_boost_ratio_numerator: Get the numerator to use for boost ratio calculation
+ * @cpu: CPU to get numerator for.
+ * @numerator: Output variable for numerator.
+ *
+ * Determine the numerator to use for calculating the boost ratio on
+ * a CPU. On systems that support preferred cores, this will be a hardcoded
+ * value. On other systems this will the highest performance register value.
+ *
+ * Return: 0 for success, negative error code otherwise.
+ */
+int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
 {
 	struct cpuinfo_x86 *c = &boot_cpu_data;
 
 	if (c->x86 == 0x17 && ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||
-			       (c->x86_model >= 0x70 && c->x86_model < 0x80)))
-		return 166;
+			       (c->x86_model >= 0x70 && c->x86_model < 0x80))) {
+		*numerator = 166;
+		return 0;
+	}
 
 	if (c->x86 == 0x19 && ((c->x86_model >= 0x20 && c->x86_model < 0x30) ||
-			       (c->x86_model >= 0x40 && c->x86_model < 0x70)))
-		return 166;
+			       (c->x86_model >= 0x40 && c->x86_model < 0x70))) {
+		*numerator = 166;
+		return 0;
+	}
+	*numerator = 255;
 
-	return 255;
+	return 0;
 }
-EXPORT_SYMBOL_GPL(amd_get_highest_perf);
+EXPORT_SYMBOL_GPL(amd_get_boost_ratio_numerator);
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index a8ca625a98b89..0f04feb6cafaf 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -642,10 +642,16 @@ static u64 get_max_boost_ratio(unsigned int cpu)
 		return 0;
 	}
 
-	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
-		highest_perf = amd_get_highest_perf();
-	else
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+		ret = amd_get_boost_ratio_numerator(cpu, &highest_perf);
+		if (ret) {
+			pr_debug("CPU%d: Unable to get boost ratio numerator (%d)\n",
+				 cpu, ret);
+			return 0;
+		}
+	} else {
 		highest_perf = perf_caps.highest_perf;
+	}
 
 	nominal_perf = perf_caps.nominal_perf;
 
diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index 930b6afba6f4d..f25a881cd46dd 100644
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -136,6 +136,12 @@ struct cppc_cpudata {
 	cpumask_var_t shared_cpu_map;
 };
 
+#ifdef CONFIG_CPU_SUP_AMD
+extern int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator);
+#else /* !CONFIG_CPU_SUP_AMD */
+static inline int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) { return -ENODEV; }
+#endif /* !CONFIG_CPU_SUP_AMD */
+
 #ifdef CONFIG_ACPI_CPPC_LIB
 extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
 extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf);
-- 
2.43.0