drivers/char/hvc_lguest.c

   1 /* Simple console for lguest.
   2  *
   3  * Copyright (C) 2006 Rusty Russell, IBM Corporation
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19 #include <linux/err.h>
  20 #include <linux/init.h>
  21 #include <linux/lguest_bus.h>
  22 #include "hvc_console.h"
  23
  24 static char inbuf[256];
  25 static struct lguest_dma cons_input = { .used_len = 0,
  26                                         .addr[0] = __pa(inbuf),
  27                                         .len[0] = sizeof(inbuf),
  28                                         .len[1] = 0 };
  29
  30 static int put_chars(u32 vtermno, const char *buf, int count)
  31 {
  32         struct lguest_dma dma;
  33
  34         /* FIXME: what if it's over a page boundary? */
  35         dma.len[0] = count;
  36         dma.len[1] = 0;
  37         dma.addr[0] = __pa(buf);
  38
  39         lguest_send_dma(LGUEST_CONSOLE_DMA_KEY, &dma);
  40         return count;
  41 }
  42
  43 static int get_chars(u32 vtermno, char *buf, int count)
  44 {
  45         static int cons_offset;
  46
  47         if (!cons_input.used_len)
  48                 return 0;
  49
  50         if (cons_input.used_len - cons_offset < count)
  51                 count = cons_input.used_len - cons_offset;
  52
  53         memcpy(buf, inbuf + cons_offset, count);
  54         cons_offset += count;
  55         if (cons_offset == cons_input.used_len) {
  56                 cons_offset = 0;
  57                 cons_input.used_len = 0;
  58         }
  59         return count;
  60 }
  61
  62 static struct hv_ops lguest_cons = {
  63         .get_chars = get_chars,
  64         .put_chars = put_chars,
  65 };
  66
  67 static int __init cons_init(void)
  68 {
  69         if (strcmp(paravirt_ops.name, "lguest") != 0)
  70                 return 0;
  71
  72         return hvc_instantiate(0, 0, &lguest_cons);
  73 }
  74 console_initcall(cons_init);
  75
  76 static int lguestcons_probe(struct lguest_device *lgdev)
  77 {
  78         int err;
  79
  80         lgdev->private = hvc_alloc(0, lgdev_irq(lgdev), &lguest_cons, 256);
  81         if (IS_ERR(lgdev->private))
  82                 return PTR_ERR(lgdev->private);
  83
  84         err = lguest_bind_dma(LGUEST_CONSOLE_DMA_KEY, &cons_input, 1,
  85                               lgdev_irq(lgdev));
  86         if (err)
  87                 printk("lguest console: failed to bind buffer.\n");
  88         return err;
  89 }
  90
  91 static struct lguest_driver lguestcons_drv = {
  92         .name = "lguestcons",
  93         .owner = THIS_MODULE,
  94         .device_type = LGUEST_DEVICE_T_CONSOLE,
  95         .probe = lguestcons_probe,
  96 };
  97
  98 static int __init hvc_lguest_init(void)
  99 {
 100         return register_lguest_driver(&lguestcons_drv);
 101 }
 102 module_init(hvc_lguest_init);