1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * hvconsole.c
4 * Copyright (C) 2004 Hollis Blanchard, IBM Corporation
5 * Copyright (C) 2004 IBM Corporation
6 *
7 * Additional Author(s):
8 *  Ryan S. Arnold <rsa@us.ibm.com>
9 *
10 * LPAR console support.
11 */
12
13#include <linux/kernel.h>
14#include <linux/export.h>
15#include <linux/errno.h>
16#include <asm/hvcall.h>
17#include <asm/hvconsole.h>
18#include <asm/plpar_wrappers.h>
19
20/**
21 * hvc_get_chars - retrieve characters from firmware for denoted vterm adapter
22 * @vtermno: The vtermno or unit_address of the adapter from which to fetch the
23 *	data.
24 * @buf: The character buffer into which to put the character data fetched from
25 *	firmware.
26 * @count: not used?
27 */
28ssize_t hvc_get_chars(uint32_t vtermno, u8 *buf, size_t count)
29{
30	long ret;
31	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
32	unsigned long *lbuf = (unsigned long *)buf;
33
34	ret = plpar_hcall(H_GET_TERM_CHAR, retbuf, vtermno);
35	lbuf[0] = be64_to_cpu(retbuf[1]);
36	lbuf[1] = be64_to_cpu(retbuf[2]);
37
38	if (ret == H_SUCCESS)
39		return retbuf[0];
40
41	return 0;
42}
43
44EXPORT_SYMBOL(hvc_get_chars);
45
46
47/**
48 * hvc_put_chars: send characters to firmware for denoted vterm adapter
49 * @vtermno: The vtermno or unit_address of the adapter from which the data
50 *	originated.
51 * @buf: The character buffer that contains the character data to send to
52 *	firmware. Must be at least 16 bytes, even if count is less than 16.
53 * @count: Send this number of characters.
54 */
55ssize_t hvc_put_chars(uint32_t vtermno, const u8 *buf, size_t count)
56{
57	unsigned long *lbuf = (unsigned long *) buf;
58	long ret;
59
60
61	/* hcall will ret H_PARAMETER if 'count' exceeds firmware max.*/
62	if (count > MAX_VIO_PUT_CHARS)
63		count = MAX_VIO_PUT_CHARS;
64
65	ret = plpar_hcall_norets(H_PUT_TERM_CHAR, vtermno, count,
66				 cpu_to_be64(lbuf[0]),
67				 cpu_to_be64(lbuf[1]));
68	if (ret == H_SUCCESS)
69		return count;
70	if (ret == H_BUSY)
71		return -EAGAIN;
72	return -EIO;
73}
74
75EXPORT_SYMBOL(hvc_put_chars);
76