/******************************************************************************
 * kernel.c
 * 
 * Assorted crap goes here, including the initial C entry point, jumped at
 * from head.S.
 * 
 * Copyright (c) 2002-2003, K A Fraser & R Neugebauer
 * Copyright (c) 2005, Grzegorz Milos, Intel Research Cambridge
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
 * DEALINGS IN THE SOFTWARE.
 */

#include <os.h>
#include <hypervisor.h>
#include <mm.h>
#include <events.h>
#include <time.h>
#include <types.h>
#include <lib.h>
#include <sched.h>
#include <xenbus.h>
#include <xen/features.h>
#include <xen/version.h>

/*
 * Shared page for communicating with the hypervisor.
 * Events flags go here, for example.
 */
shared_info_t *HYPERVISOR_shared_info;

/*
 * This structure contains start-of-day info, such as pagetable base pointer,
 * address of the shared_info structure, and things like that.
 */
union start_info_union start_info_union;

/*
 * Just allocate the kernel stack here. SS:ESP is set up to point here
 * in head.S.
 */
char stack[8192];


/* Assembler interface fns in entry.S. */
void hypervisor_callback(void);
void failsafe_callback(void);

extern char shared_info[PAGE_SIZE];

#if !defined(CONFIG_X86_PAE)
#define __pte(x) ((pte_t) { (x) } )
#else
#define __pte(x) ({ unsigned long long _x = (x);        \
    ((pte_t) {(unsigned long)(_x), (unsigned long)(_x>>32)}); })
#endif

static shared_info_t *map_shared_info(unsigned long pa)
{
    if ( HYPERVISOR_update_va_mapping(
        (unsigned long)shared_info, __pte(pa | 7), UVMF_INVLPG) )
    {
        printk("Failed to map shared_info!!\n");
        do_exit();
    }
    return (shared_info_t *)shared_info;
}


void test_xenbus(void);

/* Do initialisation from a thread once the scheduler's available */
static void init_xs(void *ign)
{
    init_xenbus();

    test_xenbus();
}


u8 xen_features[XENFEAT_NR_SUBMAPS * 32];

void setup_xen_features(void)
{
    xen_feature_info_t fi;
    int i, j;

    for (i = 0; i < XENFEAT_NR_SUBMAPS; i++) 
    {
        fi.submap_idx = i;
        if (HYPERVISOR_xen_version(XENVER_get_features, &fi) < 0)
            break;
        
        for (j=0; j<32; j++)
            xen_features[i*32+j] = !!(fi.submap & 1<<j);
    }
}

/* This should be overridden by the application we are linked against. */
__attribute__((weak)) int app_main(start_info_t *si)
{
    printk("Dummy main: start_info=%p\n", si);
    return 0;
}

/*
 * INITIAL C ENTRY POINT.
 */
void start_kernel(start_info_t *si)
{
    static char hello[] = "Bootstrapping...\n";

    (void)HYPERVISOR_console_io(CONSOLEIO_write, strlen(hello), hello);

    /* Copy the start_info struct to a globally-accessible area. */
    /* WARN: don't do printk before here, it uses information from
       shared_info. Use xprintk instead. */
    memcpy(&start_info, si, sizeof(*si));
    
    /* set up minimal memory infos */
    phys_to_machine_mapping = (unsigned long *)start_info.mfn_list;

    /* Grab the shared_info pointer and put it in a safe place. */
    HYPERVISOR_shared_info = map_shared_info(start_info.shared_info);

    /* Set up event and failsafe callback addresses. */
#ifdef __i386__
    HYPERVISOR_set_callbacks(
        __KERNEL_CS, (unsigned long)hypervisor_callback,
        __KERNEL_CS, (unsigned long)failsafe_callback);
#else
    HYPERVISOR_set_callbacks(
        (unsigned long)hypervisor_callback,
        (unsigned long)failsafe_callback, 0);
#endif
    trap_init();

    /* ENABLE EVENT DELIVERY. This is disabled at start of day. */
    __sti();
    
    /* print out some useful information  */
    printk("Xen Minimal OS!\n");
    printk("start_info:   %p\n",    si);
    printk("  nr_pages:   %lu",     si->nr_pages);
    printk("  shared_inf: %08lx\n", si->shared_info);
    printk("  pt_base:    %p",      (void *)si->pt_base); 
    printk("  mod_start:  0x%lx\n", si->mod_start);
    printk("  mod_len:    %lu\n",   si->mod_len); 
    printk("  flags:      0x%x\n",  (unsigned int)si->flags);
    printk("  cmd_line:   %s\n",  
           si->cmd_line ? (const char *)si->cmd_line : "NULL");
    printk("  stack:      %p-%p\n", stack, stack + 8192);

    setup_xen_features();

    /* Init memory management. */
    init_mm();

    /* Set up events. */
    init_events();
    
    /* Init time and timers. */
    init_time();

    /* Init the console driver. */
    init_console();
 
    /* Init scheduler. */
    init_sched();
 
    /* Init XenBus from a separate thread */
    create_thread("init_xs", init_xs, NULL);

    /* Call (possibly overridden) app_main() */
    app_main(&start_info);

    /* Everything initialised, start idle thread */
    run_idle_thread();
}


/*
 * do_exit: This is called whenever an IRET fails in entry.S.
 * This will generally be because an application has got itself into
 * a really bad state (probably a bad CS or SS). It must be killed.
 * Of course, minimal OS doesn't have applications :-)
 */

void do_exit(void)
{
    printk("Do_exit called!\n");
    for ( ;; ) HYPERVISOR_sched_op(SCHEDOP_shutdown, SHUTDOWN_crash);
}