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x86/tsc: Remove CPUID "frequency" leaf magic numbers.

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All the code that reads the CPUID frequency information leaf hard-codes
a magic number.  Give it a symbolic name and use it.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/all/20241213205036.4397658F%40davehans-spike.ostc.intel.com
This commit is contained in:
Dave Hansen 2024-12-13 12:50:36 -08:00
parent 030c15b561
commit e558eadf6b
2 changed files with 7 additions and 6 deletions
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1
arch/x86/include/asm/cpuid.h
View File

@ -24,6 +24,7 @@ enum cpuid_regs_idx {
#define CPUID_MWAIT_LEAF 0x5
#define CPUID_DCA_LEAF 0x9
#define CPUID_TSC_LEAF 0x15
#define CPUID_FREQ_LEAF 0x16
#ifdef CONFIG_X86_32
bool have_cpuid_p(void);

12
arch/x86/kernel/tsc.c
View File

@ -681,8 +681,8 @@ unsigned long native_calibrate_tsc(void)
/*
* Denverton SoCs don't report crystal clock, and also don't support
* CPUID.0x16 for the calculation below, so hardcode the 25MHz crystal
* clock.
* CPUID_FREQ_LEAF for the calculation below, so hardcode the 25MHz
* crystal clock.
*/
if (crystal_khz == 0 &&
boot_cpu_data.x86_vfm == INTEL_ATOM_GOLDMONT_D)
@ -701,10 +701,10 @@ unsigned long native_calibrate_tsc(void)
* clock, but we can easily calculate it to a high degree of accuracy
* by considering the crystal ratio and the CPU speed.
*/
if (crystal_khz == 0 && boot_cpu_data.cpuid_level >= 0x16) {
if (crystal_khz == 0 && boot_cpu_data.cpuid_level >= CPUID_FREQ_LEAF) {
unsigned int eax_base_mhz, ebx, ecx, edx;
cpuid(0x16, &eax_base_mhz, &ebx, &ecx, &edx);
cpuid(CPUID_FREQ_LEAF, &eax_base_mhz, &ebx, &ecx, &edx);
crystal_khz = eax_base_mhz * 1000 *
eax_denominator / ebx_numerator;
}
@ -739,12 +739,12 @@ static unsigned long cpu_khz_from_cpuid(void)
if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
return 0;
if (boot_cpu_data.cpuid_level < 0x16)
if (boot_cpu_data.cpuid_level < CPUID_FREQ_LEAF)
return 0;
eax_base_mhz = ebx_max_mhz = ecx_bus_mhz = edx = 0;
cpuid(0x16, &eax_base_mhz, &ebx_max_mhz, &ecx_bus_mhz, &edx);
cpuid(CPUID_FREQ_LEAF, &eax_base_mhz, &ebx_max_mhz, &ecx_bus_mhz, &edx);
return eax_base_mhz * 1000;
}