drivers/char/hvc_xen.c

   1 /*
   2  * xen console driver interface to hvc_console.c
   3  *
   4  * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19  */
  20
  21 #include <linux/console.h>
  22 #include <linux/delay.h>
  23 #include <linux/err.h>
  24 #include <linux/init.h>
  25 #include <linux/types.h>
  26
  27 #include <asm/xen/hypervisor.h>
  28 #include <xen/page.h>
  29 #include <xen/events.h>
  30 #include <xen/interface/io/console.h>
  31 #include <xen/hvc-console.h>
  32
  33 #include "hvc_console.h"
  34
  35 #define HVC_COOKIE   0x58656e /* "Xen" in hex */
  36
  37 static struct hvc_struct *hvc;
  38 static int xencons_irq;
  39
  40 /* ------------------------------------------------------------------ */
  41
  42 static unsigned long console_pfn = ~0ul;
  43
  44 static inline struct xencons_interface *xencons_interface(void)
  45 {
  46         if (console_pfn == ~0ul)
  47                 return mfn_to_virt(xen_start_info->console.domU.mfn);
  48         else
  49                 return __va(console_pfn << PAGE_SHIFT);
  50 }
  51
  52 static inline void notify_daemon(void)
  53 {
  54         /* Use evtchn: this is called early, before irq is set up. */
  55         notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
  56 }
  57
  58 static int __write_console(const char *data, int len)
  59 {
  60         struct xencons_interface *intf = xencons_interface();
  61         XENCONS_RING_IDX cons, prod;
  62         int sent = 0;
  63
  64         cons = intf->out_cons;
  65         prod = intf->out_prod;
  66         mb();                   /* update queue values before going on */
  67         BUG_ON((prod - cons) > sizeof(intf->out));
  68
  69         while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
  70                 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
  71
  72         wmb();                  /* write ring before updating pointer */
  73         intf->out_prod = prod;
  74
  75         notify_daemon();
  76         return sent;
  77 }
  78
  79 static int write_console(uint32_t vtermno, const char *data, int len)
  80 {
  81         int ret = len;
  82
  83         /*
  84          * Make sure the whole buffer is emitted, polling if
  85          * necessary.  We don't ever want to rely on the hvc daemon
  86          * because the most interesting console output is when the
  87          * kernel is crippled.
  88          */
  89         while (len) {
  90                 int sent = __write_console(data, len);
  91
  92                 data += sent;
  93                 len -= sent;
  94
  95                 if (unlikely(len))
  96                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
  97         }
  98
  99         return ret;
 100 }
 101
 102 static int read_console(uint32_t vtermno, char *buf, int len)
 103 {
 104         struct xencons_interface *intf = xencons_interface();
 105         XENCONS_RING_IDX cons, prod;
 106         int recv = 0;
 107
 108         cons = intf->in_cons;
 109         prod = intf->in_prod;
 110         mb();                   /* get pointers before reading ring */
 111         BUG_ON((prod - cons) > sizeof(intf->in));
 112
 113         while (cons != prod && recv < len)
 114                 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
 115
 116         mb();                   /* read ring before consuming */
 117         intf->in_cons = cons;
 118
 119         notify_daemon();
 120         return recv;
 121 }
 122
 123 static struct hv_ops hvc_ops = {
 124         .get_chars = read_console,
 125         .put_chars = write_console,
 126         .notifier_add = notifier_add_irq,
 127         .notifier_del = notifier_del_irq,
 128         .notifier_hangup = notifier_hangup_irq,
 129 };
 130
 131 static int __init xen_init(void)
 132 {
 133         struct hvc_struct *hp;
 134
 135         if (!xen_pv_domain() ||
 136             xen_initial_domain() ||
 137             !xen_start_info->console.domU.evtchn)
 138                 return -ENODEV;
 139
 140         xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
 141         if (xencons_irq < 0)
 142                 xencons_irq = 0; /* NO_IRQ */
 143
 144         hp = hvc_alloc(HVC_COOKIE, xencons_irq, &hvc_ops, 256);
 145         if (IS_ERR(hp))
 146                 return PTR_ERR(hp);
 147
 148         hvc = hp;
 149
 150         console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
 151
 152         return 0;
 153 }
 154
 155 void xen_console_resume(void)
 156 {
 157         if (xencons_irq)
 158                 rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
 159 }
 160
 161 static void __exit xen_fini(void)
 162 {
 163         if (hvc)
 164                 hvc_remove(hvc);
 165 }
 166
 167 static int xen_cons_init(void)
 168 {
 169         if (!xen_pv_domain())
 170                 return 0;
 171
 172         hvc_instantiate(HVC_COOKIE, 0, &hvc_ops);
 173         return 0;
 174 }
 175
 176 module_init(xen_init);
 177 module_exit(xen_fini);
 178 console_initcall(xen_cons_init);
 179
 180 static void raw_console_write(const char *str, int len)
 181 {
 182         while(len > 0) {
 183                 int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
 184                 if (rc <= 0)
 185                         break;
 186
 187                 str += rc;
 188                 len -= rc;
 189         }
 190 }
 191
 192 #ifdef CONFIG_EARLY_PRINTK
 193 static void xenboot_write_console(struct console *console, const char *string,
 194                                   unsigned len)
 195 {
 196         unsigned int linelen, off = 0;
 197         const char *pos;
 198
 199         raw_console_write(string, len);
 200
 201         write_console(0, "(early) ", 8);
 202         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 203                 linelen = pos-string+off;
 204                 if (off + linelen > len)
 205                         break;
 206                 write_console(0, string+off, linelen);
 207                 write_console(0, "\r\n", 2);
 208                 off += linelen + 1;
 209         }
 210         if (off < len)
 211                 write_console(0, string+off, len-off);
 212 }
 213
 214 struct console xenboot_console = {
 215         .name           = "xenboot",
 216         .write          = xenboot_write_console,
 217         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 218 };
 219 #endif  /* CONFIG_EARLY_PRINTK */
 220
 221 void xen_raw_console_write(const char *str)
 222 {
 223         raw_console_write(str, strlen(str));
 224 }
 225
 226 void xen_raw_printk(const char *fmt, ...)
 227 {
 228         static char buf[512];
 229         va_list ap;
 230
 231         va_start(ap, fmt);
 232         vsnprintf(buf, sizeof(buf), fmt, ap);
 233         va_end(ap);
 234
 235         xen_raw_console_write(buf);
 236 }