mtrr.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <cpu/x86/msr.h>
#include <cpu/x86/mtrr.h>
#include <soc/pci_devs.h>
#include <soc/reg_access.h>
 
asmlinkage void *soc_set_mtrrs(void *top_of_stack)
{
        union {
                uint32_t u32[2];
                uint64_t u64;
                msr_t msr;
        } data;
        uint32_t mtrr_count;
        uint32_t *mtrr_data;
        uint32_t mtrr_reg;
 
        /*
         * The stack contents are initialized in src/soc/intel/common/stack.c
         * to be the following:
         *
         *                              *
         *                              *
         *                              *
         *                 +36: MTRR mask 1 63:32
         *                 +32: MTRR mask 1 31:0
         *                 +28: MTRR base 1 63:32
         *                 +24: MTRR base 1 31:0
         *                 +20: MTRR mask 0 63:32
         *                 +16: MTRR mask 0 31:0
         *                 +12: MTRR base 0 63:32
         *                  +8: MTRR base 0 31:0
         *                  +4: Number of MTRRs to setup (described above)
         * top_of_stack --> +0: Number of variable MTRRs to clear
         *
         * This routine:
         *      * Clears all of the variable MTRRs
         *      * Initializes the variable MTRRs with the data passed in
         *      * Returns the new top of stack after removing all of the
         *        data passed in.
         */
 
        /* Clear all of the variable MTRRs (base and mask). */
        mtrr_reg = MTRR_PHYS_BASE(0);
        mtrr_data = top_of_stack;
        mtrr_count = (*mtrr_data++) * 2;
        data.u64 = 0;
        while (mtrr_count-- > 0)
                soc_msr_write(mtrr_reg++, data.msr);
 
        /* Setup the specified variable MTRRs */
        mtrr_reg = MTRR_PHYS_BASE(0);
        mtrr_count = *mtrr_data++;
        while (mtrr_count-- > 0) {
                data.u32[0] = *mtrr_data++;
                data.u32[1] = *mtrr_data++;
                soc_msr_write(mtrr_reg++, data.msr); /* Base */
                data.u32[0] = *mtrr_data++;
                data.u32[1] = *mtrr_data++;
                soc_msr_write(mtrr_reg++, data.msr); /* Mask */
        }
 
        /* Remove setup_stack_and_mtrrs data and return the new top_of_stack */
        top_of_stack = mtrr_data;
        return top_of_stack;
}
 
asmlinkage void soc_enable_mtrrs(void)
{
        union {
                uint32_t u32[2];
                uint64_t u64;
                msr_t msr;
        } data;
 
        /* Enable MTRR. */
        data.msr = soc_msr_read(MTRR_DEF_TYPE_MSR);
        data.u32[0] |= MTRR_DEF_TYPE_EN;
        soc_msr_write(MTRR_DEF_TYPE_MSR, data.msr);
}