diff options
Diffstat (limited to 'src/cpu/amd/agesa/family15tn')
| -rw-r--r-- | src/cpu/amd/agesa/family15tn/Makefile.inc | 2 | ||||
| -rw-r--r-- | src/cpu/amd/agesa/family15tn/udelay.c | 45 |
2 files changed, 47 insertions, 0 deletions
diff --git a/src/cpu/amd/agesa/family15tn/Makefile.inc b/src/cpu/amd/agesa/family15tn/Makefile.inc index 19a2f0f298..a8f644d241 100644 --- a/src/cpu/amd/agesa/family15tn/Makefile.inc +++ b/src/cpu/amd/agesa/family15tn/Makefile.inc @@ -20,6 +20,8 @@ ramstage-y += chip_name.c ramstage-y += model_15_init.c +smm-$(CONFIG_HAVE_SMI_HANDLER) += udelay.c + subdirs-y += ../../mtrr subdirs-y += ../../smm subdirs-y += ../../../x86/tsc diff --git a/src/cpu/amd/agesa/family15tn/udelay.c b/src/cpu/amd/agesa/family15tn/udelay.c new file mode 100644 index 0000000000..5873237b0c --- /dev/null +++ b/src/cpu/amd/agesa/family15tn/udelay.c @@ -0,0 +1,45 @@ +/* + * udelay() impementation for SMI handlers + * This is neat in that it never writes to hardware registers, and thus does not + * modify the state of the hardware while servicing SMIs. + * + * Copyright (C) 2014 Alexandru Gagniuc <mr.nuke.me@gmail.com> + * Subject to the GNU GPL v2, or (at your option) any later version. + */ + +#include <cpu/x86/msr.h> +#include <cpu/x86/tsc.h> +#include <delay.h> +#include <stdint.h> + +void udelay(uint32_t us) +{ + uint8_t fid, did, pstate_idx; + uint64_t tsc_clock, tsc_start, tsc_now, tsc_wait_ticks; + msr_t msr; + const uint64_t tsc_base = 100000000; + + /* Get initial timestamp before we do the math */ + tsc_start = rdtscll(); + + /* Get the P-state. This determines which MSR to read */ + msr = rdmsr(0xc0010063); + pstate_idx = msr.lo & 0x07; + + /* Get FID and VID for current P-State */ + msr = rdmsr(0xc0010064 + pstate_idx); + + /* Extract the FID and VID values */ + fid = msr.lo & 0x3f; + did = (msr.lo >> 6) & 0x7; + + /* Calculate the CPU clock (from base freq of 100MHz) */ + tsc_clock = tsc_base * (fid + 0x10) / (1 << did); + + /* Now go on and wait */ + tsc_wait_ticks = (tsc_clock / 1000000) * us; + + do { + tsc_now = rdtscll(); + } while (tsc_now - tsc_wait_ticks < tsc_start); +} |