Normally U-Boot handles MTRRs through an add/commit process which overwrites all MTRRs. But in very early boot it is not desirable to clear the existing MTRRs since they may be in use and it can cause a hang.
Add a new mtrr_set_next_var() function which sets up the next available MTRR to the required region.
Signed-off-by: Simon Glass sjg@chromium.org ---
arch/x86/cpu/mtrr.c | 38 +++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/mtrr.h | 12 ++++++++++++ 2 files changed, 50 insertions(+)
diff --git a/arch/x86/cpu/mtrr.c b/arch/x86/cpu/mtrr.c index 6218d149e30..1a7c292fa8b 100644 --- a/arch/x86/cpu/mtrr.c +++ b/arch/x86/cpu/mtrr.c @@ -112,3 +112,41 @@ int mtrr_add_request(int type, uint64_t start, uint64_t size)
return 0; } + +static int get_var_mtrr_count(void) +{ + return msr_read(MSR_MTRR_CAP_MSR).lo & MSR_MTRR_CAP_VCNT; +} + +static int get_free_var_mtrr(void) +{ + struct msr_t maskm; + int vcnt; + int i; + + vcnt = get_var_mtrr_count(); + + /* Identify the first var mtrr which is not valid */ + for (i = 0; i < vcnt; i++) { + maskm = msr_read(MTRR_PHYS_MASK_MSR(i)); + if ((maskm.lo & MTRR_PHYS_MASK_VALID) == 0) + return i; + } + + /* No free var mtrr */ + return -ENOSPC; +} + +int mtrr_set_next_var(uint type, uint64_t start, uint64_t size) +{ + int mtrr; + + mtrr = get_free_var_mtrr(); + if (mtrr < 0) + return mtrr; + + set_var_mtrr(mtrr, MTRR_TYPE_WRPROT, start, size); + debug("MTRR %x: start=%x, size=%x\n", mtrr, (uint)start, (uint)size); + + return 0; +} diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h index 6f29e75ce65..672617256e9 100644 --- a/arch/x86/include/asm/mtrr.h +++ b/arch/x86/include/asm/mtrr.h @@ -117,6 +117,18 @@ int mtrr_add_request(int type, uint64_t start, uint64_t size); */ int mtrr_commit(bool do_caches);
+/** + * mtrr_set_next_var() - set up a variable MTRR + * + * This finds the first free variable MTRR and sets to the given area + * + * @type: Requested type (MTRR_TYPE_) + * @start: Start address + * @size: Size + * @return 0 on success, -ENOSPC if there are no more MTRRs + */ +int mtrr_set_next_var(uint type, uint64_t base, uint64_t size); + #endif
#if ((CONFIG_XIP_ROM_SIZE & (CONFIG_XIP_ROM_SIZE - 1)) != 0)