pc-bios/s390-ccw/netmain.c

   1 /*
   2  * S390 virtio-ccw network boot loading program
   3  *
   4  * Copyright 2017 Thomas Huth, Red Hat Inc.
   5  *
   6  * Based on the S390 virtio-ccw loading program (main.c)
   7  * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
   8  *
   9  * This code is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the
  11  * Free Software Foundation; either version 2 of the License, or (at your
  12  * option) any later version.
  13  */
  14
  15 #include <stdint.h>
  16 #include <stdbool.h>
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <unistd.h>
  21 #include <time.h>
  22
  23 #include "s390-ccw.h"
  24 #include "virtio.h"
  25
  26 extern char _start[];
  27
  28 char stack[PAGE_SIZE * 8] __attribute__((aligned(PAGE_SIZE)));
  29 IplParameterBlock iplb __attribute__((aligned(PAGE_SIZE)));
  30
  31 static SubChannelId net_schid = { .one = 1 };
  32 static uint64_t dest_timer;
  33
  34 static uint64_t get_timer_ms(void)
  35 {
  36     uint64_t clk;
  37
  38     asm volatile(" stck %0 " : : "Q"(clk) : "memory");
  39
  40     /* Bit 51 is incremented each microsecond */
  41     return (clk >> (63 - 51)) / 1000;
  42 }
  43
  44 void set_timer(int val)
  45 {
  46     dest_timer = get_timer_ms() + val;
  47 }
  48
  49 int get_timer(void)
  50 {
  51     return dest_timer - get_timer_ms();
  52 }
  53
  54 int get_sec_ticks(void)
  55 {
  56     return 1000;    /* number of ticks in 1 second */
  57 }
  58
  59 void panic(const char *string)
  60 {
  61     sclp_print(string);
  62     for (;;) {
  63         disabled_wait();
  64     }
  65 }
  66
  67 static bool find_net_dev(Schib *schib, int dev_no)
  68 {
  69     int i, r;
  70
  71     for (i = 0; i < 0x10000; i++) {
  72         net_schid.sch_no = i;
  73         r = stsch_err(net_schid, schib);
  74         if (r == 3 || r == -EIO) {
  75             break;
  76         }
  77         if (!schib->pmcw.dnv) {
  78             continue;
  79         }
  80         if (!virtio_is_supported(net_schid)) {
  81             continue;
  82         }
  83         if (virtio_get_device_type() != VIRTIO_ID_NET) {
  84             continue;
  85         }
  86         if (dev_no < 0 || schib->pmcw.dev == dev_no) {
  87             return true;
  88         }
  89     }
  90
  91     return false;
  92 }
  93
  94 static void virtio_setup(void)
  95 {
  96     Schib schib;
  97     int ssid;
  98     bool found = false;
  99     uint16_t dev_no;
 100
 101     /*
 102      * We unconditionally enable mss support. In every sane configuration,
 103      * this will succeed; and even if it doesn't, stsch_err() can deal
 104      * with the consequences.
 105      */
 106     enable_mss_facility();
 107
 108     if (store_iplb(&iplb)) {
 109         IPL_assert(iplb.pbt == S390_IPL_TYPE_CCW, "IPL_TYPE_CCW expected");
 110         dev_no = iplb.ccw.devno;
 111         debug_print_int("device no. ", dev_no);
 112         net_schid.ssid = iplb.ccw.ssid & 0x3;
 113         debug_print_int("ssid ", net_schid.ssid);
 114         found = find_net_dev(&schib, dev_no);
 115     } else {
 116         for (ssid = 0; ssid < 0x3; ssid++) {
 117             net_schid.ssid = ssid;
 118             found = find_net_dev(&schib, -1);
 119             if (found) {
 120                 break;
 121             }
 122         }
 123     }
 124
 125     IPL_assert(found, "No virtio net device found");
 126 }
 127
 128 void main(void)
 129 {
 130     sclp_setup();
 131     sclp_print("Network boot starting...\n");
 132
 133     virtio_setup();
 134
 135     panic("Failed to load OS from network\n");
 136 }