arch/powerpc/platforms/pseries/hvconsole.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * hvconsole.c
 * Copyright (C) 2004 Hollis Blanchard, IBM Corporation
 * Copyright (C) 2004 IBM Corporation
 *
 * Additional Author(s):
 *  Ryan S. Arnold <rsa@us.ibm.com>
 *
 * LPAR console support.
 */

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/errno.h>
#include <asm/hvcall.h>
#include <asm/hvconsole.h>
#include <asm/plpar_wrappers.h>

/**
 * hvc_get_chars - retrieve characters from firmware for denoted vterm adapter
 * @vtermno: The vtermno or unit_address of the adapter from which to fetch the
 *	data.
 * @buf: The character buffer into which to put the character data fetched from
 *	firmware.
 * @count: not used?
 */
ssize_t hvc_get_chars(uint32_t vtermno, u8 *buf, size_t count)
{
	long ret;
	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
	unsigned long *lbuf = (unsigned long *)buf;

	ret = plpar_hcall(H_GET_TERM_CHAR, retbuf, vtermno);
	lbuf[0] = be64_to_cpu(retbuf[1]);
	lbuf[1] = be64_to_cpu(retbuf[2]);

	if (ret == H_SUCCESS)
		return retbuf[0];

	return 0;
}

EXPORT_SYMBOL(hvc_get_chars);


/**
 * hvc_put_chars: send characters to firmware for denoted vterm adapter
 * @vtermno: The vtermno or unit_address of the adapter from which the data
 *	originated.
 * @buf: The character buffer that contains the character data to send to
 *	firmware. Must be at least 16 bytes, even if count is less than 16.
 * @count: Send this number of characters.
 */
ssize_t hvc_put_chars(uint32_t vtermno, const u8 *buf, size_t count)
{
	unsigned long *lbuf = (unsigned long *) buf;
	long ret;


	/* hcall will ret H_PARAMETER if 'count' exceeds firmware max.*/
	if (count > MAX_VIO_PUT_CHARS)
		count = MAX_VIO_PUT_CHARS;

	ret = plpar_hcall_norets(H_PUT_TERM_CHAR, vtermno, count,
				 cpu_to_be64(lbuf[0]),
				 cpu_to_be64(lbuf[1]));
	if (ret == H_SUCCESS)
		return count;
	if (ret == H_BUSY)
		return -EAGAIN;
	return -EIO;
}

EXPORT_SYMBOL(hvc_put_chars);