diff options
| -rw-r--r-- | src/soc/intel/apollolake/bootblock/bootblock.c | 9 | ||||
| -rw-r--r-- | src/soc/intel/apollolake/include/soc/cpu.h | 3 |
2 files changed, 10 insertions, 2 deletions
diff --git a/src/soc/intel/apollolake/bootblock/bootblock.c b/src/soc/intel/apollolake/bootblock/bootblock.c index cd23f5984b..77d98d98be 100644 --- a/src/soc/intel/apollolake/bootblock/bootblock.c +++ b/src/soc/intel/apollolake/bootblock/bootblock.c @@ -41,8 +41,13 @@ static void enable_pm_timer(void) { /* ACPI PM timer emulation */ msr_t msr; - /* Multiplier value that somehow 3.579545MHz freq */ - msr.hi = 0x2FBA2E25; + /* + * The derived frequency is calculated as follows: + * (CTC_FREQ * msr[63:32]) >> 32 = target frequency. + * Back solve the multiplier so the 3.579545MHz ACPI timer + * frequency is used. + */ + msr.hi = (3579545ULL << 32) / CTC_FREQ; /* Set PM1 timer IO port and enable*/ msr.lo = EMULATE_PM_TMR_EN | (ACPI_PMIO_BASE + R_ACPI_PM1_TMR); wrmsr(MSR_EMULATE_PM_TMR, msr); diff --git a/src/soc/intel/apollolake/include/soc/cpu.h b/src/soc/intel/apollolake/include/soc/cpu.h index b731d4f539..78fc0b0df6 100644 --- a/src/soc/intel/apollolake/include/soc/cpu.h +++ b/src/soc/intel/apollolake/include/soc/cpu.h @@ -37,4 +37,7 @@ void apollolake_init_cpus(struct device *dev); #define BASE_CLOCK_MHZ 100 +/* Common Timer Copy (CTC) frequency - 19.2MHz. */ +#define CTC_FREQ 19200000 + #endif /* _SOC_APOLLOLAKE_CPU_H_ */ |