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 #define RTASCONS_PUT_ATTEMPTS  16
  45
  46 static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
  47 static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;
  48 static int rtascons_put_delay = 100;
  49 module_param_named(put_delay, rtascons_put_delay, int, 0644);
  50
  51 static inline int hvc_rtas_write_console(uint32_t vtermno, const char *buf, int count)
  52 {
  53         int done;
  54
  55         /* if there is more than one character to be displayed, wait a bit */
  56         for (done = 0; done < count; done++) {
  57                 int result;
  58                 result = rtas_call(rtascons_put_char_token, 1, 1, NULL, buf[done]);
  59                 if (result)
  60                         break;
  61         }
  62         /* the calling routine expects to receive the number of bytes sent */
  63         return done;
  64 }
  65
  66 static int hvc_rtas_read_console(uint32_t vtermno, char *buf, int count)
  67 {
  68         int i;
  69
  70         for (i = 0; i < count; i++) {
  71                 int c, err;
  72
  73                 err = rtas_call(rtascons_get_char_token, 0, 2, &c);
  74                 if (err)
  75                         break;
  76
  77                 buf[i] = c;
  78         }
  79
  80         return i;
  81 }
  82
  83 static struct hv_ops hvc_rtas_get_put_ops = {
  84         .get_chars = hvc_rtas_read_console,
  85         .put_chars = hvc_rtas_write_console,
  86 };
  87
  88 static int hvc_rtas_init(void)
  89 {
  90         struct hvc_struct *hp;
  91
  92         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  93                 rtascons_put_char_token = rtas_token("put-term-char");
  94         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  95                 return -EIO;
  96
  97         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
  98                 rtascons_get_char_token = rtas_token("get-term-char");
  99         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
 100                 return -EIO;
 101
 102         BUG_ON(hvc_rtas_dev);
 103
 104         /* Allocate an hvc_struct for the console device we instantiated
 105          * earlier.  Save off hp so that we can return it on exit */
 106         hp = hvc_alloc(hvc_rtas_cookie, NO_IRQ, &hvc_rtas_get_put_ops);
 107         if (IS_ERR(hp))
 108                 return PTR_ERR(hp);
 109         hvc_rtas_dev = hp;
 110         return 0;
 111 }
 112 module_init(hvc_rtas_init);
 113
 114 /* This will tear down the tty portion of the driver */
 115 static void __exit hvc_rtas_exit(void)
 116 {
 117         /* Really the fun isn't over until the worker thread breaks down and the
 118          * tty cleans up */
 119         if (hvc_rtas_dev)
 120                 hvc_remove(hvc_rtas_dev);
 121 }
 122 module_exit(hvc_rtas_exit);
 123
 124 /* This will happen prior to module init.  There is no tty at this time? */
 125 static int hvc_rtas_console_init(void)
 126 {
 127         rtascons_put_char_token = rtas_token("put-term-char");
 128         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
 129                 return -EIO;
 130         rtascons_get_char_token = rtas_token("get-term-char");
 131         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
 132                 return -EIO;
 133
 134         hvc_instantiate(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops );
 135         add_preferred_console("hvc", 0, NULL);
 136         return 0;
 137 }
 138 console_initcall(hvc_rtas_console_init);