pc-bios/s390-ccw/main.c

   1 /*
   2  * S390 virtio-ccw loading program
   3  *
   4  * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2 or (at
   7  * your option) any later version. See the COPYING file in the top-level
   8  * directory.
   9  */
  10
  11 #include "s390-ccw.h"
  12 #include "virtio.h"
  13
  14 char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
  15 uint64_t boot_value;
  16 static SubChannelId blk_schid = { .one = 1 };
  17
  18 /*
  19  * Priniciples of Operations (SA22-7832-09) chapter 17 requires that
  20  * a subsystem-identification is at 184-187 and bytes 188-191 are zero
  21  * after list-directed-IPL and ccw-IPL.
  22  */
  23 void write_subsystem_identification(void)
  24 {
  25     SubChannelId *schid = (SubChannelId *) 184;
  26     uint32_t *zeroes = (uint32_t *) 188;
  27
  28     *schid = blk_schid;
  29     *zeroes = 0;
  30 }
  31
  32
  33 void panic(const char *string)
  34 {
  35     sclp_print(string);
  36     disabled_wait();
  37     while (1) { }
  38 }
  39
  40 static bool find_dev(Schib *schib, int dev_no)
  41 {
  42     int i, r;
  43
  44     for (i = 0; i < 0x10000; i++) {
  45         blk_schid.sch_no = i;
  46         r = stsch_err(blk_schid, schib);
  47         if ((r == 3) || (r == -EIO)) {
  48             break;
  49         }
  50         if (!schib->pmcw.dnv) {
  51             continue;
  52         }
  53         if (!virtio_is_supported(blk_schid)) {
  54             continue;
  55         }
  56         if ((dev_no < 0) || (schib->pmcw.dev == dev_no)) {
  57             return true;
  58         }
  59     }
  60
  61     return false;
  62 }
  63
  64 static void virtio_setup(uint64_t dev_info)
  65 {
  66     Schib schib;
  67     int ssid;
  68     bool found = false;
  69     uint16_t dev_no;
  70
  71     /*
  72      * We unconditionally enable mss support. In every sane configuration,
  73      * this will succeed; and even if it doesn't, stsch_err() can deal
  74      * with the consequences.
  75      */
  76     enable_mss_facility();
  77
  78     if (dev_info != -1) {
  79         dev_no = dev_info & 0xffff;
  80         debug_print_int("device no. ", dev_no);
  81         blk_schid.ssid = (dev_info >> 16) & 0x3;
  82         debug_print_int("ssid ", blk_schid.ssid);
  83         found = find_dev(&schib, dev_no);
  84     } else {
  85         for (ssid = 0; ssid < 0x3; ssid++) {
  86             blk_schid.ssid = ssid;
  87             found = find_dev(&schib, -1);
  88             if (found) {
  89                 break;
  90             }
  91         }
  92     }
  93
  94     IPL_assert(found, "No virtio device found");
  95
  96     virtio_setup_device(blk_schid);
  97
  98     IPL_assert(virtio_ipl_disk_is_valid(), "No valid IPL device detected");
  99 }
 100
 101 int main(void)
 102 {
 103     sclp_setup();
 104     debug_print_int("boot reg[7] ", boot_value);
 105     virtio_setup(boot_value);
 106
 107     zipl_load(); /* no return */
 108
 109     panic("Failed to load OS from hard disk\n");
 110     return 0; /* make compiler happy */
 111 }