From 3ba6a0f4f6a2381ad32930df6277930a3de577bc Mon Sep 17 00:00:00 2001 From: Bin Meng Date: Tue, 6 Jan 2015 22:14:14 +0800 Subject: x86: Allow a hardcoded TSC frequency provided by Kconfig 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 Acked-by: Simon Glass --- arch/x86/lib/tsc_timer.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'arch/x86/lib/tsc_timer.c') diff --git a/arch/x86/lib/tsc_timer.c b/arch/x86/lib/tsc_timer.c index fb9afed18f..7f5ba2ca6f 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; -- cgit