linux/drivers/tty/hvc/hvc_rtas.c
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   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
  29struct hvc_struct *hvc_rtas_dev;
  30
  31static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
  32static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;
  33
  34static 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
  47static 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
  61static 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
  66static 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}
  92device_initcall(hvc_rtas_init);
  93
  94/* This will happen prior to module init.  There is no tty at this time? */
  95static 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}
 110console_initcall(hvc_rtas_console_init);
 111