bootblock.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <arch/bootblock.h>
#include <assert.h>
#include <device/pci_ops.h>
#include <types.h>
 
#include "gm45.h"
 
static uint32_t encode_pciexbar_length(void)
{
        switch (CONFIG_ECAM_MMCONF_BUS_NUMBER) {
                case 256: return 0 << 1;
                case 128: return 1 << 1;
                case  64: return 2 << 1;
                default:  return dead_code_t(uint32_t);
        }
}
 
void bootblock_early_northbridge_init(void)
{
        /*
         * The "io" variant of the config access is explicitly used to
         * setup the PCIEXBAR because CONFIG(ECAM_MMCONF_SUPPORT) is set to
         * true. That way all subsequent non-explicit config accesses use
         * MCFG. This code also assumes that bootblock_northbridge_init() is
         * the first thing called in the non-asm boot block code. The final
         * assumption is that no assembly code is using the
         * CONFIG(ECAM_MMCONF_SUPPORT) option to do PCI config accesses.
         *
         * The PCIEXBAR is assumed to live in the memory mapped IO space under
         * 4GiB.
         */
        const uint32_t reg32 = CONFIG_ECAM_MMCONF_BASE_ADDRESS | encode_pciexbar_length() | 1;
        pci_io_write_config32(PCI_DEV(0, 0, 0), D0F0_PCIEXBAR_HI, 0);
        pci_io_write_config32(PCI_DEV(0, 0, 0), D0F0_PCIEXBAR_LO, reg32);
}