Commit e558eadf authored by Dave Hansen's avatar Dave Hansen
Browse files

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



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: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarZhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/all/20241213205036.4397658F%40davehans-spike.ostc.intel.com
parent 030c15b5

arch/x86/include/asm/cpuid.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/tsc.c

+6 −6
Original line number Diff line number Diff line
@@ -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;

}