Furquan Shaikh (furquan@google.com) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/14115
-gerrit
commit 7d5754b2f646e8dbc304e26bd344f2fd499a063e Author: Furquan Shaikh furquan@google.com Date: Wed Mar 16 16:12:06 2016 -0700
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 --- src/cpu/x86/mtrr/earlymtrr.c | 24 ++++++++++++++++++++++++ src/include/cpu/x86/mtrr.h | 1 + 2 files changed, 25 insertions(+)
diff --git a/src/cpu/x86/mtrr/earlymtrr.c b/src/cpu/x86/mtrr/earlymtrr.c index a84ecf8..bc16a29 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) + return i; + } + + /* No free var mtrr. */ + return -1; +} + #ifdef __ROMCC__ static #endif diff --git a/src/include/cpu/x86/mtrr.h b/src/include/cpu/x86/mtrr.h index d158735..4eb4f13 100644 --- a/src/include/cpu/x86/mtrr.h +++ b/src/include/cpu/x86/mtrr.h @@ -81,6 +81,7 @@ void x86_mtrr_check(void);
#if !defined(__ASSEMBLER__) && defined(__PRE_RAM__) && !defined(__ROMCC__) void set_var_mtrr(unsigned reg, unsigned base, unsigned size, unsigned type); +int get_free_var_mtrr(void); #endif
/* Align up to next power of 2, suitable for ROMCC and assembler too.