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 domU_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 domU_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 struct hv_ops domU_hvc_ops = {
 127         .get_chars = domU_read_console,
 128         .put_chars = domU_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 dom0_read_console(uint32_t vtermno, char *buf, int len)
 135 {
 136         return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
 137 }
 138
 139 /*
 140  * Either for a dom0 to write to the system console, or a domU with a
 141  * debug version of Xen
 142  */
 143 static int dom0_write_console(uint32_t vtermno, const char *str, int len)
 144 {
 145         int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
 146         if (rc < 0)
 147                 return 0;
 148
 149         return len;
 150 }
 151
 152 static struct hv_ops dom0_hvc_ops = {
 153         .get_chars = dom0_read_console,
 154         .put_chars = dom0_write_console,
 155         .notifier_add = notifier_add_irq,
 156         .notifier_del = notifier_del_irq,
 157         .notifier_hangup = notifier_hangup_irq,
 158 };
 159
 160 static int __init xen_hvc_init(void)
 161 {
 162         struct hvc_struct *hp;
 163         struct hv_ops *ops;
 164
 165         if (!xen_pv_domain())
 166                 return -ENODEV;
 167
 168         if (xen_initial_domain()) {
 169                 ops = &dom0_hvc_ops;
 170                 xencons_irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
 171         } else {
 172                 if (!xen_start_info->console.domU.evtchn)
 173                         return -ENODEV;
 174
 175                 ops = &domU_hvc_ops;
 176                 xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
 177         }
 178         if (xencons_irq < 0)
 179                 xencons_irq = 0; /* NO_IRQ */
 180
 181         hp = hvc_alloc(HVC_COOKIE, xencons_irq, ops, 256);
 182         if (IS_ERR(hp))
 183                 return PTR_ERR(hp);
 184
 185         hvc = hp;
 186
 187         console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
 188
 189         return 0;
 190 }
 191
 192 void xen_console_resume(void)
 193 {
 194         if (xencons_irq)
 195                 rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
 196 }
 197
 198 static void __exit xen_hvc_fini(void)
 199 {
 200         if (hvc)
 201                 hvc_remove(hvc);
 202 }
 203
 204 static int xen_cons_init(void)
 205 {
 206         struct hv_ops *ops;
 207
 208         if (!xen_pv_domain())
 209                 return 0;
 210
 211         if (xen_initial_domain())
 212                 ops = &dom0_hvc_ops;
 213         else
 214                 ops = &domU_hvc_ops;
 215
 216         hvc_instantiate(HVC_COOKIE, 0, ops);
 217         return 0;
 218 }
 219
 220 module_init(xen_hvc_init);
 221 module_exit(xen_hvc_fini);
 222 console_initcall(xen_cons_init);
 223
 224 #ifdef CONFIG_EARLY_PRINTK
 225 static void xenboot_write_console(struct console *console, const char *string,
 226                                   unsigned len)
 227 {
 228         unsigned int linelen, off = 0;
 229         const char *pos;
 230
 231         dom0_write_console(0, string, len);
 232
 233         if (xen_initial_domain())
 234                 return;
 235
 236         domU_write_console(0, "(early) ", 8);
 237         while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 238                 linelen = pos-string+off;
 239                 if (off + linelen > len)
 240                         break;
 241                 domU_write_console(0, string+off, linelen);
 242                 domU_write_console(0, "\r\n", 2);
 243                 off += linelen + 1;
 244         }
 245         if (off < len)
 246                 domU_write_console(0, string+off, len-off);
 247 }
 248
 249 struct console xenboot_console = {
 250         .name           = "xenboot",
 251         .write          = xenboot_write_console,
 252         .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
 253 };
 254 #endif  /* CONFIG_EARLY_PRINTK */
 255
 256 void xen_raw_console_write(const char *str)
 257 {
 258         dom0_write_console(0, str, strlen(str));
 259 }
 260
 261 void xen_raw_printk(const char *fmt, ...)
 262 {
 263         static char buf[512];
 264         va_list ap;
 265
 266         va_start(ap, fmt);
 267         vsnprintf(buf, sizeof(buf), fmt, ap);
 268         va_end(ap);
 269
 270         xen_raw_console_write(buf);
 271 }