// SPDX-License-Identifier: GPL-2.0
/*
 * arch/alpha/boot/main.c
 *
 * Copyright (C) 1994, 1995 Linus Torvalds
 *
 * This file is the bootloader for the Linux/AXP kernel
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <generated/utsrelease.h>
#include <linux/mm.h>

#include <asm/console.h>
#include <asm/hwrpb.h>

#include <linux/stdarg.h>

#include "ksize.h"

extern unsigned long switch_to_osf_pal(unsigned long nr,
        struct pcb_struct * pcb_va, struct pcb_struct * pcb_pa,
        unsigned long *vptb);
struct hwrpb_struct *hwrpb = INIT_HWRPB;
static struct pcb_struct pcb_va[1];

/*
 * Find a physical address of a virtual object..
 *
 * This is easy using the virtual page table address.
 */

static inline void *
find_pa(unsigned long *vptb, void *ptr)
{
        unsigned long address = (unsigned long) ptr;
        unsigned long result;

        result = vptb[address >> 13];
        result >>= 32;
        result <<= 13;
        result |= address & 0x1fff;
        return (void *) result;
}       

/*
 * This function moves into OSF/1 pal-code, and has a temporary
 * PCB for that. The kernel proper should replace this PCB with
 * the real one as soon as possible.
 *
 * The page table muckery in here depends on the fact that the boot
 * code has the L1 page table identity-map itself in the second PTE
 * in the L1 page table. Thus the L1-page is virtually addressable
 * itself (through three levels) at virtual address 0x200802000.
 */

#define VPTB    ((unsigned long *) 0x200000000)
#define L1      ((unsigned long *) 0x200802000)

void
pal_init(void)
{
        unsigned long i, rev;
        struct percpu_struct * percpu;
        struct pcb_struct * pcb_pa;

        /* Create the dummy PCB.  */
        pcb_va->ksp = 0;
        pcb_va->usp = 0;
        pcb_va->ptbr = L1[1] >> 32;
        pcb_va->asn = 0;
        pcb_va->pcc = 0;
        pcb_va->unique = 0;
        pcb_va->flags = 1;
        pcb_va->res1 = 0;
        pcb_va->res2 = 0;
        pcb_pa = find_pa(VPTB, pcb_va);

        /*
         * a0 = 2 (OSF)
         * a1 = return address, but we give the asm the vaddr of the PCB
         * a2 = physical addr of PCB
         * a3 = new virtual page table pointer
         * a4 = KSP (but the asm sets it)
         */
        srm_printk("Switching to OSF PAL-code .. ");

        i = switch_to_osf_pal(2, pcb_va, pcb_pa, VPTB);
        if (i) {
                srm_printk("failed, code %ld\n", i);
                __halt();
        }

        percpu = (struct percpu_struct *)
                (INIT_HWRPB->processor_offset + (unsigned long) INIT_HWRPB);
        rev = percpu->pal_revision = percpu->palcode_avail[2];

        srm_printk("Ok (rev %lx)\n", rev);

        tbia(); /* do it directly in case we are SMP */
}

static inline long openboot(void)
{
        char bootdev[256];
        long result;

        result = callback_getenv(ENV_BOOTED_DEV, bootdev, 255);
        if (result < 0)
                return result;
        return callback_open(bootdev, result & 255);
}

static inline long close(long dev)
{
        return callback_close(dev);
}

static inline long load(long dev, unsigned long addr, unsigned long count)
{
        char bootfile[256];
        extern char _end;
        long result, boot_size = &_end - (char *) BOOT_ADDR;

        result = callback_getenv(ENV_BOOTED_FILE, bootfile, 255);
        if (result < 0)
                return result;
        result &= 255;
        bootfile[result] = '\0';
        if (result)
                srm_printk("Boot file specification (%s) not implemented\n",
                       bootfile);
        return callback_read(dev, count, (void *)addr, boot_size/512 + 1);
}

/*
 * Start the kernel.
 */
static void runkernel(void)
{
        __asm__ __volatile__(
                "bis %1,%1,$30\n\t"
                "bis %0,%0,$26\n\t"
                "ret ($26)"
                : /* no outputs: it doesn't even return */
                : "r" (START_ADDR),
                  "r" (PAGE_SIZE + INIT_STACK));
}

void start_kernel(void)
{
        long i;
        long dev;
        int nbytes;
        char envval[256];

        srm_printk("Linux/AXP bootloader for Linux " UTS_RELEASE "\n");
        if (INIT_HWRPB->pagesize != 8192) {
                srm_printk("Expected 8kB pages, got %ldkB\n", INIT_HWRPB->pagesize >> 10);
                return;
        }
        pal_init();
        dev = openboot();
        if (dev < 0) {
                srm_printk("Unable to open boot device: %016lx\n", dev);
                return;
        }
        dev &= 0xffffffff;
        srm_printk("Loading vmlinux ...");
        i = load(dev, START_ADDR, KERNEL_SIZE);
        close(dev);
        if (i != KERNEL_SIZE) {
                srm_printk("Failed (%lx)\n", i);
                return;
        }

        nbytes = callback_getenv(ENV_BOOTED_OSFLAGS, envval, sizeof(envval));
        if (nbytes < 0) {
                nbytes = 0;
        }
        envval[nbytes] = '\0';
        strcpy((char*)ZERO_PGE, envval);

        srm_printk(" Ok\nNow booting the kernel\n");
        runkernel();
        for (i = 0 ; i < 0x100000000 ; i++)
                /* nothing */;
        __halt();
}