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         if (sent)
  78                 notify_daemon();
  79         return sent;
  80 }
  81
  82 static int write_console(uint32_t vtermno, const char *data, int len)
  83 {
  84         int ret = len;
  85
  86         /*
  87          * Make sure the whole buffer is emitted, polling if
  88          * necessary.  We don't ever want to rely on the hvc daemon
  89          * because the most interesting console output is when the
  90          * kernel is crippled.
  91          */
  92         while (len) {
  93                 int sent = __write_console(data, len);
  94
  95                 data += sent;
  96                 len -= sent;
  97
  98                 if (unlikely(len))
  99                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
 100         }
 101
 102         return ret;
 103 }
 104
 105 static int read_console(uint32_t vtermno, char *buf, int len)
 106 {
 107         struct xencons_interface *intf = xencons_interface();
 108         XENCONS_RING_IDX cons, prod;
 109         int recv = 0;
 110
 111         cons = intf->in_cons;
 112         prod = intf->in_prod;
 113         mb();                   /* get pointers before reading ring */
 114         BUG_ON((prod - cons) > sizeof(intf->in));
 115
 116         while (cons != prod && recv < len)
 117                 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
 118
 119         mb();                   /* read ring before consuming */
 120         intf->in_cons = cons;
 121
 122         notify_daemon();
 123         return recv;
 124 }
 125
 126 static const struct hv_ops hvc_ops = {
 127         .get_chars = read_console,
 128         .put_chars = write_console,
 129         .notifier_add = notifier_add_irq,
 130         .notifier_del = notifier_del_irq,
 131         .notifier_hangup = notifier_hangup_irq,
 132 };
 133
 134 static int __init xen_init(void)
 135 {
 136         struct hvc_struct *hp;
 137
 138         if (!xen_pv_domain() ||
 139             xen_initial_domain() ||
 140             !xen_start_info->console.domU.evtchn)
 141                 return -ENODEV;
 142
 143         xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
 144         if (xencons_irq < 0)
 145                 xencons_irq = 0; /* NO_IRQ */
 146
 147         hp = hvc_alloc(HVC_COOKIE, xencons_irq, &hvc_ops, 256);
 148         if (IS_ERR(hp))
 149                 return PTR_ERR(hp);
 150
 151         hvc = hp;
 152
 153         console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
 154
 155         return 0;
 156 }
 157
 158 void xen_console_resume(void)
 159 {
 160         if (xencons_irq)
 161                 rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
 162 }
 163
 164 static void __exit xen_fini(void)
 165 {
 166         if (hvc)
 167                 hvc_remove(hvc);
 168 }
 169
 170 static int xen_cons_init(void)
 171 {
 172         if (!xen_pv_domain())
 173                 return 0;
 174
 175         hvc_instantiate(HVC_COOKIE, 0, &hvc_ops);
 176         return 0;
 177 }
 178
 179 module_init(xen_init);
 180 module_exit(xen_fini);
 181 console_initcall(xen_cons_init);
 182
 183 static void raw_console_write(const char *str, int len)
 184 {
 185         while(len > 0) {
 186                 int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
 187                 if (rc <= 0)
 188                         break;
 189
 190                 str += rc;
 191                 len -= rc;
 192         }
 193 }
 194
 195 #ifdef CONFIG_EARLY_PRINTK
 196 static void xenboot_write_console(struct console *console, const char *string,
 197                                   unsigned len)
 198 {
 199         unsigned int linelen, off = 0;
 200         const char *pos;
 201
 202         raw_console_write(string, len);
 203
 204         write_console(0, "(early) ", 8);
 205         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 206                 linelen = pos-string+off;
 207                 if (off + linelen > len)
 208                         break;
 209                 write_console(0, string+off, linelen);
 210                 write_console(0, "\r\n", 2);
 211                 off += linelen + 1;
 212         }
 213         if (off < len)
 214                 write_console(0, string+off, len-off);
 215 }
 216
 217 struct console xenboot_console = {
 218         .name           = "xenboot",
 219         .write          = xenboot_write_console,
 220         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 221 };
 222 #endif  /* CONFIG_EARLY_PRINTK */
 223
 224 void xen_raw_console_write(const char *str)
 225 {
 226         raw_console_write(str, strlen(str));
 227 }
 228
 229 void xen_raw_printk(const char *fmt, ...)
 230 {
 231         static char buf[512];
 232         va_list ap;
 233
 234         va_start(ap, fmt);
 235         vsnprintf(buf, sizeof(buf), fmt, ap);
 236         va_end(ap);
 237
 238         xen_raw_console_write(buf);
 239 }