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
  29 #include <xen/xen.h>
  30 #include <xen/page.h>
  31 #include <xen/events.h>
  32 #include <xen/interface/io/console.h>
  33 #include <xen/hvc-console.h>
  34
  35 #include "hvc_console.h"
  36
  37 #define HVC_COOKIE   0x58656e /* "Xen" in hex */
  38
  39 static struct hvc_struct *hvc;
  40 static int xencons_irq;
  41
  42 /* ------------------------------------------------------------------ */
  43
  44 static unsigned long console_pfn = ~0ul;
  45
  46 static inline struct xencons_interface *xencons_interface(void)
  47 {
  48         if (console_pfn == ~0ul)
  49                 return mfn_to_virt(xen_start_info->console.domU.mfn);
  50         else
  51                 return __va(console_pfn << PAGE_SHIFT);
  52 }
  53
  54 static inline void notify_daemon(void)
  55 {
  56         /* Use evtchn: this is called early, before irq is set up. */
  57         notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
  58 }
  59
  60 static int __write_console(const char *data, int len)
  61 {
  62         struct xencons_interface *intf = xencons_interface();
  63         XENCONS_RING_IDX cons, prod;
  64         int sent = 0;
  65
  66         cons = intf->out_cons;
  67         prod = intf->out_prod;
  68         mb();                   /* update queue values before going on */
  69         BUG_ON((prod - cons) > sizeof(intf->out));
  70
  71         while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
  72                 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
  73
  74         wmb();                  /* write ring before updating pointer */
  75         intf->out_prod = prod;
  76
  77         notify_daemon();
  78         return sent;
  79 }
  80
  81 static int write_console(uint32_t vtermno, const char *data, int len)
  82 {
  83         int ret = len;
  84
  85         /*
  86          * Make sure the whole buffer is emitted, polling if
  87          * necessary.  We don't ever want to rely on the hvc daemon
  88          * because the most interesting console output is when the
  89          * kernel is crippled.
  90          */
  91         while (len) {
  92                 int sent = __write_console(data, len);
  93
  94                 data += sent;
  95                 len -= sent;
  96
  97                 if (unlikely(len))
  98                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
  99         }
 100
 101         return ret;
 102 }
 103
 104 static int read_console(uint32_t vtermno, char *buf, int len)
 105 {
 106         struct xencons_interface *intf = xencons_interface();
 107         XENCONS_RING_IDX cons, prod;
 108         int recv = 0;
 109
 110         cons = intf->in_cons;
 111         prod = intf->in_prod;
 112         mb();                   /* get pointers before reading ring */
 113         BUG_ON((prod - cons) > sizeof(intf->in));
 114
 115         while (cons != prod && recv < len)
 116                 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
 117
 118         mb();                   /* read ring before consuming */
 119         intf->in_cons = cons;
 120
 121         notify_daemon();
 122         return recv;
 123 }
 124
 125 static const struct hv_ops hvc_ops = {
 126         .get_chars = read_console,
 127         .put_chars = write_console,
 128         .notifier_add = notifier_add_irq,
 129         .notifier_del = notifier_del_irq,
 130         .notifier_hangup = notifier_hangup_irq,
 131 };
 132
 133 static int __init xen_init(void)
 134 {
 135         struct hvc_struct *hp;
 136
 137         if (!xen_pv_domain() ||
 138             xen_initial_domain() ||
 139             !xen_start_info->console.domU.evtchn)
 140                 return -ENODEV;
 141
 142         xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
 143         if (xencons_irq < 0)
 144                 xencons_irq = 0; /* NO_IRQ */
 145
 146         hp = hvc_alloc(HVC_COOKIE, xencons_irq, &hvc_ops, 256);
 147         if (IS_ERR(hp))
 148                 return PTR_ERR(hp);
 149
 150         hvc = hp;
 151
 152         console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
 153
 154         return 0;
 155 }
 156
 157 void xen_console_resume(void)
 158 {
 159         if (xencons_irq)
 160                 rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
 161 }
 162
 163 static void __exit xen_fini(void)
 164 {
 165         if (hvc)
 166                 hvc_remove(hvc);
 167 }
 168
 169 static int xen_cons_init(void)
 170 {
 171         if (!xen_pv_domain())
 172                 return 0;
 173
 174         hvc_instantiate(HVC_COOKIE, 0, &hvc_ops);
 175         return 0;
 176 }
 177
 178 module_init(xen_init);
 179 module_exit(xen_fini);
 180 console_initcall(xen_cons_init);
 181
 182 static void raw_console_write(const char *str, int len)
 183 {
 184         while(len > 0) {
 185                 int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
 186                 if (rc <= 0)
 187                         break;
 188
 189                 str += rc;
 190                 len -= rc;
 191         }
 192 }
 193
 194 #ifdef CONFIG_EARLY_PRINTK
 195 static void xenboot_write_console(struct console *console, const char *string,
 196                                   unsigned len)
 197 {
 198         unsigned int linelen, off = 0;
 199         const char *pos;
 200
 201         raw_console_write(string, len);
 202
 203         write_console(0, "(early) ", 8);
 204         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 205                 linelen = pos-string+off;
 206                 if (off + linelen > len)
 207                         break;
 208                 write_console(0, string+off, linelen);
 209                 write_console(0, "\r\n", 2);
 210                 off += linelen + 1;
 211         }
 212         if (off < len)
 213                 write_console(0, string+off, len-off);
 214 }
 215
 216 struct console xenboot_console = {
 217         .name           = "xenboot",
 218         .write          = xenboot_write_console,
 219         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 220 };
 221 #endif  /* CONFIG_EARLY_PRINTK */
 222
 223 void xen_raw_console_write(const char *str)
 224 {
 225         raw_console_write(str, strlen(str));
 226 }
 227
 228 void xen_raw_printk(const char *fmt, ...)
 229 {
 230         static char buf[512];
 231         va_list ap;
 232
 233         va_start(ap, fmt);
 234         vsnprintf(buf, sizeof(buf), fmt, ap);
 235         va_end(ap);
 236
 237         xen_raw_console_write(buf);
 238 }