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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved. */
#include <linux/init.h>
#include <asm/dcc.h>
#include <asm/processor.h>
#include "hvc_console.h"
/* DCC Status Bits */
#define DCC_STATUS_RX (1 << 30)
#define DCC_STATUS_TX (1 << 29)
static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
{
int i;
for (i = 0; i < count; i++) {
while (__dcc_getstatus() & DCC_STATUS_TX)
cpu_relax();
__dcc_putchar(buf[i]);
}
return count;
}
static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
{
int i;
for (i = 0; i < count; ++i)
if (__dcc_getstatus() & DCC_STATUS_RX)
buf[i] = __dcc_getchar();
else
break;
return i;
}
static bool hvc_dcc_check(void)
{
unsigned long time = jiffies + (HZ / 10);
/* Write a test character to check if it is handled */
__dcc_putchar('\n');
while (time_is_after_jiffies(time)) {
if (!(__dcc_getstatus() & DCC_STATUS_TX))
return true;
}
return false;
}
static const struct hv_ops hvc_dcc_get_put_ops = {
.get_chars = hvc_dcc_get_chars,
.put_chars = hvc_dcc_put_chars,
};
static int __init hvc_dcc_console_init(void)
{
int ret;
if (!hvc_dcc_check())
return -ENODEV;
/* Returns -1 if error */
ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
return ret < 0 ? -ENODEV : 0;
}
console_initcall(hvc_dcc_console_init);
static int __init hvc_dcc_init(void)
{
struct hvc_struct *p;
if (!hvc_dcc_check())
return -ENODEV;
p = hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
return PTR_ERR_OR_ZERO(p);
}
device_initcall(hvc_dcc_init);
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