/*
 * Copyright (c) 2014 Google, Inc
 * Copyright (C) 2000 Ronald G. Minnich
 *
 * Microcode update for Intel PIII and later CPUs
 *
 * SPDX-License-Identifier:     GPL-2.0
 */

#include <common.h>
#include <errno.h>
#include <fdtdec.h>
#include <libfdt.h>
#include <asm/cpu.h>
#include <asm/microcode.h>
#include <asm/msr.h>
#include <asm/msr-index.h>
#include <asm/processor.h>

DECLARE_GLOBAL_DATA_PTR;

/**
 * struct microcode_update - standard microcode header from Intel
 *
 * We read this information out of the device tree and use it to determine
 * whether the update is applicable or not. We also use the same structure
 * to read information from the CPU.
 */
struct microcode_update {
        uint header_version;
        uint update_revision;
        uint date_code;
        uint processor_signature;
        uint checksum;
        uint loader_revision;
        uint processor_flags;
        const void *data;
        int size;
};

static int microcode_decode_node(const void *blob, int node,
                                 struct microcode_update *update)
{
        update->data = fdt_getprop(blob, node, "data", &update->size);
        if (!update->data)
                return -ENOENT;
        update->data += UCODE_HEADER_LEN;
        update->size -= UCODE_HEADER_LEN;

        update->header_version = fdtdec_get_int(blob, node,
                                                "intel,header-version", 0);
        update->update_revision = fdtdec_get_int(blob, node,
                                                 "intel,update-revision", 0);
        update->date_code = fdtdec_get_int(blob, node,
                                           "intel,date-code", 0);
        update->processor_signature = fdtdec_get_int(blob, node,
                                        "intel,processor-signature", 0);
        update->checksum = fdtdec_get_int(blob, node, "intel,checksum", 0);
        update->loader_revision = fdtdec_get_int(blob, node,
                                                 "intel,loader-revision", 0);
        update->processor_flags = fdtdec_get_int(blob, node,
                                                 "intel,processor-flags", 0);

        return 0;
}

int microcode_read_rev(void)
{
        /* Quark does not have microcode MSRs */
#ifdef CONFIG_INTEL_QUARK
        return 0;
#else
        /*
         * Some Intel CPUs can be very finicky about the CPUID sequence used.
         * So this is implemented in assembly so that it works reliably.
         */
        uint32_t low, high;

        asm volatile (
                "xorl %%eax, %%eax\n"
                "xorl %%edx, %%edx\n"
                "movl %2, %%ecx\n"
                "wrmsr\n"
                "movl $0x01, %%eax\n"
                "cpuid\n"
                "movl %2, %%ecx\n"
                "rdmsr\n"
                : /* outputs */
                "=a" (low), "=d" (high)
                : /* inputs */
                "i" (MSR_IA32_UCODE_REV)
                : /* clobbers */
                 "ebx", "ecx"
        );

        return high;
#endif
}

static void microcode_read_cpu(struct microcode_update *cpu)
{
        /* CPUID sets MSR 0x8B iff a microcode update has been loaded. */
        unsigned int x86_model, x86_family;
        struct cpuid_result result;
        uint32_t low, high;

        wrmsr(MSR_IA32_UCODE_REV, 0, 0);
        result = cpuid(1);
        rdmsr(MSR_IA32_UCODE_REV, low, cpu->update_revision);
        x86_model = (result.eax >> 4) & 0x0f;
        x86_family = (result.eax >> 8) & 0x0f;
        cpu->processor_signature = result.eax;

        cpu->processor_flags = 0;
        if ((x86_model >= 5) || (x86_family > 6)) {
                rdmsr(0x17, low, high);
                cpu->processor_flags = 1 << ((high >> 18) & 7);
        }
        debug("microcode: sig=%#x pf=%#x revision=%#x\n",
              cpu->processor_signature, cpu->processor_flags,
              cpu->update_revision);
}

/* Get a microcode update from the device tree and apply it */
int microcode_update_intel(void)
{
        struct microcode_update cpu, update;
        const void *blob = gd->fdt_blob;
        int skipped;
        int count;
        int node;
        int ret;
        int rev;

        microcode_read_cpu(&cpu);
        node = 0;
        count = 0;
        skipped = 0;
        do {
                node = fdtdec_next_compatible(blob, node,
                                              COMPAT_INTEL_MICROCODE);
                if (node < 0) {
                        debug("%s: Found %d updates\n", __func__, count);
                        return count ? 0 : skipped ? -EEXIST : -ENOENT;
                }

                ret = microcode_decode_node(blob, node, &update);
                if (ret == -ENOENT && ucode_base) {
                        /*
                         * The microcode has been removed from the device tree
                         * in the build system. In that case it will have
                         * already been updated in car_init().
                         */
                        debug("%s: Microcode data not available\n", __func__);
                        skipped++;
                        continue;
                }
                if (ret) {
                        debug("%s: Unable to decode update: %d\n", __func__,
                              ret);
                        return ret;
                }
                if (!(update.processor_signature == cpu.processor_signature &&
                      (update.processor_flags & cpu.processor_flags))) {
                        debug("%s: Skipping non-matching update, sig=%x, pf=%x\n",
                              __func__, update.processor_signature,
                              update.processor_flags);
                        skipped++;
                        continue;
                }
                wrmsr(MSR_IA32_UCODE_WRITE, (ulong)update.data, 0);
                rev = microcode_read_rev();
                debug("microcode: updated to revision 0x%x date=%04x-%02x-%02x\n",
                      rev, update.date_code & 0xffff,
                      (update.date_code >> 24) & 0xff,
                      (update.date_code >> 16) & 0xff);
                if (update.update_revision != rev) {
                        printf("Microcode update failed\n");
                        return -EFAULT;
                }
                count++;
        } while (1);
}