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 static 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 ssize_t hvc_rtas_write_console(uint32_t vtermno, const u8 *buf,
  35                                       size_t count)
  36 {
  37         size_t 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 ssize_t hvc_rtas_read_console(uint32_t vtermno, u8 *buf, size_t count)
  48 {
  49         size_t i;
  50         int c;
  51
  52         for (i = 0; i < count; i++) {
  53                 if (rtas_call(rtascons_get_char_token, 0, 2, &c))
  54                         break;
  55
  56                 buf[i] = c;
  57         }
  58
  59         return i;
  60 }
  61
  62 static const struct hv_ops hvc_rtas_get_put_ops = {
  63         .get_chars = hvc_rtas_read_console,
  64         .put_chars = hvc_rtas_write_console,
  65 };
  66
  67 static int __init hvc_rtas_init(void)
  68 {
  69         struct hvc_struct *hp;
  70
  71         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  72                 rtascons_put_char_token = rtas_token("put-term-char");
  73         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
  74                 return -EIO;
  75
  76         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
  77                 rtascons_get_char_token = rtas_token("get-term-char");
  78         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
  79                 return -EIO;
  80
  81         BUG_ON(hvc_rtas_dev);
  82
  83         /* Allocate an hvc_struct for the console device we instantiated
  84          * earlier.  Save off hp so that we can return it on exit */
  85         hp = hvc_alloc(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops, 16);
  86         if (IS_ERR(hp))
  87                 return PTR_ERR(hp);
  88
  89         hvc_rtas_dev = hp;
  90
  91         return 0;
  92 }
  93 device_initcall(hvc_rtas_init);
  94
  95 /* This will happen prior to module init.  There is no tty at this time? */
  96 static int __init hvc_rtas_console_init(void)
  97 {
  98         rtascons_put_char_token = rtas_token("put-term-char");
  99         if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
 100                 return -EIO;
 101
 102         rtascons_get_char_token = rtas_token("get-term-char");
 103         if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
 104                 return -EIO;
 105
 106         hvc_instantiate(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops);
 107         add_preferred_console("hvc", 0, NULL);
 108
 109         return 0;
 110 }
 111 console_initcall(hvc_rtas_console_init);