drivers/char/hvc_rtas.c

   1 /*
   2  * IBM RTAS driver interface to hvc_console.c
   3  *
   4  * (C) Copyright IBM Corporation 2001-2005
   5  * (C) Copyright Red Hat, Inc. 2005
   6  *
   7  * Author(s): Maximino Augilar <IBM STI Design Center>
   8  *          : Ryan S. Arnold <rsa@us.ibm.com>
   9  *          : Utz Bacher <utz.bacher@de.ibm.com>
  10  *          : David Woodhouse <dwmw2@infradead.org>
  11  *
  12  *    inspired by drivers/char/hvc_console.c
  13  *    written by Anton Blanchard and Paul Mackerras
  14  *
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  28  */
  29
  30 #include <linux/console.h>
  31 #include <linux/delay.h>
  32 #include <linux/err.h>
  33 #include <linux/init.h>
  34 #include <linux/moduleparam.h>
  35 #include <linux/types.h>
  36
  37 #include <asm/irq.h>
  38 #include <asm/rtas.h>
  39 #include "hvc_console.h"
  40
  41 #define hvc_rtas_cookie 0x67781e15
  42 struct hvc_struct *hvc_rtas_dev;
  43
  44 static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
  45 static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;
  46
  47 static inline int hvc_rtas_write_console(uint32_t vtermno, const char *buf,
  48                 int count)
  49 {
  50         int i;
  51
  52         for (i = 0; i < count; i++) {
  53                 if (rtas_call(rtascons_put_char_token, 1, 1, NULL, buf[i]))
  54                         break;
  55         }
  56
  57         return i;
  58 }
  59
  60 static int hvc_rtas_read_console(uint32_t vtermno, char *buf, int count)
  61 {
  62         int i, c;
  63
  64         for (i = 0; i < count; i++) {
  65                 if (rtas_call(rtascons_get_char_token, 0, 2, &c))
  66                         break;
  67
  68                 buf[i] = c;
  69         }
  70
  71         return i;
  72 }
  73
  74 static struct hv_ops hvc_rtas_get_put_ops = {
  75         .get_chars = hvc_rtas_read_console,
  76         .put_chars = hvc_rtas_write_console,
  77 };
  78
  79 static int hvc_rtas_init(void)
  80 {
  81         struct hvc_struct *hp;
  82
  83         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  84                 rtascons_put_char_token = rtas_token("put-term-char");
  85         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  86                 return -EIO;
  87
  88         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
  89                 rtascons_get_char_token = rtas_token("get-term-char");
  90         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
  91                 return -EIO;
  92
  93         BUG_ON(hvc_rtas_dev);
  94
  95         /* Allocate an hvc_struct for the console device we instantiated
  96          * earlier.  Save off hp so that we can return it on exit */
  97         hp = hvc_alloc(hvc_rtas_cookie, NO_IRQ, &hvc_rtas_get_put_ops, 16);
  98         if (IS_ERR(hp))
  99                 return PTR_ERR(hp);
 100
 101         hvc_rtas_dev = hp;
 102
 103         return 0;
 104 }
 105 module_init(hvc_rtas_init);
 106
 107 /* This will tear down the tty portion of the driver */
 108 static void __exit hvc_rtas_exit(void)
 109 {
 110         /* Really the fun isn't over until the worker thread breaks down and
 111          * the tty cleans up */
 112         if (hvc_rtas_dev)
 113                 hvc_remove(hvc_rtas_dev);
 114 }
 115 module_exit(hvc_rtas_exit);
 116
 117 /* This will happen prior to module init.  There is no tty at this time? */
 118 static int hvc_rtas_console_init(void)
 119 {
 120         rtascons_put_char_token = rtas_token("put-term-char");
 121         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
 122                 return -EIO;
 123
 124         rtascons_get_char_token = rtas_token("get-term-char");
 125         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
 126                 return -EIO;
 127
 128         hvc_instantiate(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops);
 129         add_preferred_console("hvc", 0, NULL);
 130
 131         return 0;
 132 }
 133 console_initcall(hvc_rtas_console_init);