By default U-Boot automatically calibrates TSC running frequency via MSR and PIT. The calibration may not work on every x86 processor, so a new Kconfig option CONFIG_TSC_CALIBRATION_BYPASS is introduced to allow bypassing the calibration and assign a hardcoded TSC frequency CONFIG_TSC_FREQ_IN_MHZ.
Normally the bypass should be turned on in a simulation environment like qemu. Signed-off-by: Bin Meng <bmeng...@gmail.com> --- arch/x86/Kconfig | 18 ++++++++++++++++++ arch/x86/lib/tsc_timer.c | 8 ++++++-- 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ebf72b3..9c11f0e 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -317,6 +317,24 @@ config FRAMEBUFFER_VESA_MODE endmenu +config TSC_CALIBRATION_BYPASS + bool "Bypass TSC calibration" + default n + help + By default U-Boot automatically calibrates TSC running frequency via + MSR and PIT. If the calibration does not work on your board, select + this option and provide a hardcoded TSC running frequency below. + + Normally this option should be turned on in a simulation environment + like qemu. + +config TSC_FREQ_IN_MHZ + int "TSC running frequency in MHz" + depends on TSC_CALIBRATION_BYPASS + default 1000 + help + The running frequency in MHz of TSC + source "arch/x86/cpu/ivybridge/Kconfig" source "arch/x86/cpu/queensbay/Kconfig" diff --git a/arch/x86/lib/tsc_timer.c b/arch/x86/lib/tsc_timer.c index fb9afed..7f5ba2c 100644 --- a/arch/x86/lib/tsc_timer.c +++ b/arch/x86/lib/tsc_timer.c @@ -78,7 +78,7 @@ static int match_cpu(u8 family, u8 model) * * Returns the calibration value or 0 if MSR calibration failed. */ -static unsigned long try_msr_calibrate_tsc(void) +static unsigned long __maybe_unused try_msr_calibrate_tsc(void) { u32 lo, hi, ratio, freq_id, freq; unsigned long res; @@ -199,7 +199,7 @@ static inline int pit_expect_msb(unsigned char val, u64 *tscp, #define MAX_QUICK_PIT_MS 50 #define MAX_QUICK_PIT_ITERATIONS (MAX_QUICK_PIT_MS * PIT_TICK_RATE / 1000 / 256) -static unsigned long quick_pit_calibrate(void) +static unsigned long __maybe_unused quick_pit_calibrate(void) { int i; u64 tsc, delta; @@ -306,6 +306,9 @@ unsigned __attribute__((no_instrument_function)) long get_tbclk_mhz(void) if (gd->arch.tsc_mhz) return gd->arch.tsc_mhz; +#ifdef CONFIG_TSC_CALIBRATION_BYPASS + fast_calibrate = CONFIG_TSC_FREQ_IN_MHZ; +#else fast_calibrate = try_msr_calibrate_tsc(); if (!fast_calibrate) { @@ -313,6 +316,7 @@ unsigned __attribute__((no_instrument_function)) long get_tbclk_mhz(void) if (!fast_calibrate) panic("TSC frequency is ZERO"); } +#endif gd->arch.tsc_mhz = fast_calibrate; return fast_calibrate; -- 1.8.2.1 _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot