diff options
| author | Furquan Shaikh <furquan@google.com> | 2016-03-16 16:12:06 -0700 |
|---|---|---|
| committer | Martin Roth <martinroth@google.com> | 2016-03-18 19:14:52 +0100 |
| commit | 331ac1b07896140a14dbb079b3cb907762cec218 (patch) | |
| tree | 8352f21b1d295a9e4a9b0bc801735e584ca324ee /src/cpu/x86 | |
| parent | 39e55209dce7d971c2e5b53706c5124e1ec01bb3 (diff) | |
mtrr: Define a function for obtaining free var mtrr
Instead of hard-coding var mtrr numbers in code, use this function to
identify the first available variable mtrr. If no such mtrr is
available, the function will return -1.
Change-Id: I2a1e02cdb45c0ab7e30609641977471eaa2431fd
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/14115
Tested-by: build bot (Jenkins)
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>
Diffstat (limited to 'src/cpu/x86')
| -rw-r--r-- | src/cpu/x86/mtrr/earlymtrr.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/src/cpu/x86/mtrr/earlymtrr.c b/src/cpu/x86/mtrr/earlymtrr.c index a84ecf8f72..eae6ba67b2 100644 --- a/src/cpu/x86/mtrr/earlymtrr.c +++ b/src/cpu/x86/mtrr/earlymtrr.c @@ -2,6 +2,30 @@ #include <cpu/x86/mtrr.h> #include <cpu/x86/msr.h> +/* Get first available variable MTRR. + * Returns var# if available, else returns -1. + */ +int get_free_var_mtrr(void) +{ + msr_t msr, maskm; + int vcnt; + int i; + + /* Read MTRRCap and get vcnt - variable memory type ranges. */ + msr = rdmsr(MTRR_CAP_MSR); + vcnt = msr.lo & 0xff; + + /* Identify the first var mtrr which is not valid. */ + for (i = 0; i < vcnt; i++) { + maskm = rdmsr(MTRR_PHYS_MASK(i)); + if ((maskm.lo & MTRR_PHYS_MASK_VALID) == 0) + return i; + } + + /* No free var mtrr. */ + return -1; +} + #ifdef __ROMCC__ static #endif |