drivers/tty/hvc/hvc_udbg.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * udbg interface to hvc_console.c
   4  *
   5  * (C) Copyright David Gibson, IBM Corporation 2008.
   6  */
   7
   8 #include <linux/console.h>
   9 #include <linux/delay.h>
  10 #include <linux/err.h>
  11 #include <linux/init.h>
  12 #include <linux/moduleparam.h>
  13 #include <linux/types.h>
  14 #include <linux/irq.h>
  15
  16 #include <asm/udbg.h>
  17
  18 #include "hvc_console.h"
  19
  20 struct hvc_struct *hvc_udbg_dev;
  21
  22 static int hvc_udbg_put(uint32_t vtermno, const char *buf, int count)
  23 {
  24         int i;
  25
  26         for (i = 0; i < count && udbg_putc; i++)
  27                 udbg_putc(buf[i]);
  28
  29         return i;
  30 }
  31
  32 static int hvc_udbg_get(uint32_t vtermno, char *buf, int count)
  33 {
  34         int i, c;
  35
  36         if (!udbg_getc_poll)
  37                 return 0;
  38
  39         for (i = 0; i < count; i++) {
  40                 if ((c = udbg_getc_poll()) == -1)
  41                         break;
  42                 buf[i] = c;
  43         }
  44
  45         return i;
  46 }
  47
  48 static const struct hv_ops hvc_udbg_ops = {
  49         .get_chars = hvc_udbg_get,
  50         .put_chars = hvc_udbg_put,
  51 };
  52
  53 static int __init hvc_udbg_init(void)
  54 {
  55         struct hvc_struct *hp;
  56
  57         if (!udbg_putc)
  58                 return -ENODEV;
  59
  60         BUG_ON(hvc_udbg_dev);
  61
  62         hp = hvc_alloc(0, 0, &hvc_udbg_ops, 16);
  63         if (IS_ERR(hp))
  64                 return PTR_ERR(hp);
  65
  66         hvc_udbg_dev = hp;
  67
  68         return 0;
  69 }
  70 device_initcall(hvc_udbg_init);
  71
  72 static int __init hvc_udbg_console_init(void)
  73 {
  74         if (!udbg_putc)
  75                 return -ENODEV;
  76
  77         hvc_instantiate(0, 0, &hvc_udbg_ops);
  78         add_preferred_console("hvc", 0, NULL);
  79
  80         return 0;
  81 }
  82 console_initcall(hvc_udbg_console_init);