drivers/tty/hvc/hvc_rtas.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * IBM RTAS driver interface to hvc_console.c
   4  *
   5  * (C) Copyright IBM Corporation 2001-2005
   6  * (C) Copyright Red Hat, Inc. 2005
   7  *
   8  * Author(s): Maximino Augilar <IBM STI Design Center>
   9  *          : Ryan S. Arnold <rsa@us.ibm.com>
  10  *          : Utz Bacher <utz.bacher@de.ibm.com>
  11  *          : David Woodhouse <dwmw2@infradead.org>
  12  *
  13  *    inspired by drivers/char/hvc_console.c
  14  *    written by Anton Blanchard and Paul Mackerras
  15  */
  16
  17 #include <linux/console.h>
  18 #include <linux/delay.h>
  19 #include <linux/err.h>
  20 #include <linux/init.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/types.h>
  23
  24 #include <asm/irq.h>
  25 #include <asm/rtas.h>
  26 #include "hvc_console.h"
  27
  28 #define hvc_rtas_cookie 0x67781e15
  29 struct hvc_struct *hvc_rtas_dev;
  30
  31 static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
  32 static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;
  33
  34 static inline int hvc_rtas_write_console(uint32_t vtermno, const char *buf,
  35                 int count)
  36 {
  37         int i;
  38
  39         for (i = 0; i < count; i++) {
  40                 if (rtas_call(rtascons_put_char_token, 1, 1, NULL, buf[i]))
  41                         break;
  42         }
  43
  44         return i;
  45 }
  46
  47 static int hvc_rtas_read_console(uint32_t vtermno, char *buf, int count)
  48 {
  49         int i, c;
  50
  51         for (i = 0; i < count; i++) {
  52                 if (rtas_call(rtascons_get_char_token, 0, 2, &c))
  53                         break;
  54
  55                 buf[i] = c;
  56         }
  57
  58         return i;
  59 }
  60
  61 static const struct hv_ops hvc_rtas_get_put_ops = {
  62         .get_chars = hvc_rtas_read_console,
  63         .put_chars = hvc_rtas_write_console,
  64 };
  65
  66 static int __init hvc_rtas_init(void)
  67 {
  68         struct hvc_struct *hp;
  69
  70         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  71                 rtascons_put_char_token = rtas_token("put-term-char");
  72         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  73                 return -EIO;
  74
  75         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
  76                 rtascons_get_char_token = rtas_token("get-term-char");
  77         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
  78                 return -EIO;
  79
  80         BUG_ON(hvc_rtas_dev);
  81
  82         /* Allocate an hvc_struct for the console device we instantiated
  83          * earlier.  Save off hp so that we can return it on exit */
  84         hp = hvc_alloc(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops, 16);
  85         if (IS_ERR(hp))
  86                 return PTR_ERR(hp);
  87
  88         hvc_rtas_dev = hp;
  89
  90         return 0;
  91 }
  92 device_initcall(hvc_rtas_init);
  93
  94 /* This will happen prior to module init.  There is no tty at this time? */
  95 static int __init hvc_rtas_console_init(void)
  96 {
  97         rtascons_put_char_token = rtas_token("put-term-char");
  98         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  99                 return -EIO;
 100
 101         rtascons_get_char_token = rtas_token("get-term-char");
 102         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
 103                 return -EIO;
 104
 105         hvc_instantiate(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops);
 106         add_preferred_console("hvc", 0, NULL);
 107
 108         return 0;
 109 }
 110 console_initcall(hvc_rtas_console_init);