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 char ring_area[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
  16 uint64_t boot_value;
  17 static struct subchannel_id blk_schid = { .one = 1 };
  18
  19 /*
  20  * Priniciples of Operations (SA22-7832-09) chapter 17 requires that
  21  * a subsystem-identification is at 184-187 and bytes 188-191 are zero
  22  * after list-directed-IPL and ccw-IPL.
  23  */
  24 void write_subsystem_identification(void)
  25 {
  26     struct subchannel_id *schid = (struct subchannel_id *) 184;
  27     uint32_t *zeroes = (uint32_t *) 188;
  28
  29     *schid = blk_schid;
  30     *zeroes = 0;
  31 }
  32
  33
  34 void virtio_panic(const char *string)
  35 {
  36     sclp_print(string);
  37     disabled_wait();
  38     while (1) { }
  39 }
  40
  41 static bool find_dev(struct schib *schib, int dev_no)
  42 {
  43     int i, r;
  44
  45     for (i = 0; i < 0x10000; i++) {
  46         blk_schid.sch_no = i;
  47         r = stsch_err(blk_schid, schib);
  48         if ((r == 3) || (r == -EIO)) {
  49             break;
  50         }
  51         if (!schib->pmcw.dnv) {
  52             continue;
  53         }
  54         if (!virtio_is_blk(blk_schid)) {
  55             continue;
  56         }
  57         if ((dev_no < 0) || (schib->pmcw.dev == dev_no)) {
  58             return true;
  59         }
  60     }
  61
  62     return false;
  63 }
  64
  65 static void virtio_setup(uint64_t dev_info)
  66 {
  67     struct schib schib;
  68     int ssid;
  69     bool found = false;
  70     uint16_t dev_no;
  71
  72     /*
  73      * We unconditionally enable mss support. In every sane configuration,
  74      * this will succeed; and even if it doesn't, stsch_err() can deal
  75      * with the consequences.
  76      */
  77     enable_mss_facility();
  78
  79     if (dev_info != -1) {
  80         dev_no = dev_info & 0xffff;
  81         debug_print_int("device no. ", dev_no);
  82         blk_schid.ssid = (dev_info >> 16) & 0x3;
  83         debug_print_int("ssid ", blk_schid.ssid);
  84         found = find_dev(&schib, dev_no);
  85     } else {
  86         for (ssid = 0; ssid < 0x3; ssid++) {
  87             blk_schid.ssid = ssid;
  88             found = find_dev(&schib, -1);
  89             if (found) {
  90                 break;
  91             }
  92         }
  93     }
  94
  95     if (!found) {
  96         virtio_panic("No virtio-blk device found!\n");
  97     }
  98
  99     virtio_setup_block(blk_schid);
 100
 101     if (!virtio_ipl_disk_is_valid()) {
 102         virtio_panic("No valid hard disk detected.\n");
 103     }
 104 }
 105
 106 int main(void)
 107 {
 108     sclp_setup();
 109     debug_print_int("boot reg[7] ", boot_value);
 110     virtio_setup(boot_value);
 111
 112     zipl_load(); /* no return */
 113
 114     virtio_panic("Failed to load OS from hard disk\n");
 115     return 0; /* make compiler happy */
 116 }