1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved. */
4 #include <linux/init.h>
7 #include <asm/processor.h>
9 #include "hvc_console.h"
12 #define DCC_STATUS_RX (1 << 30)
13 #define DCC_STATUS_TX (1 << 29)
15 static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
19 for (i = 0; i < count; i++) {
20 while (__dcc_getstatus() & DCC_STATUS_TX)
23 __dcc_putchar(buf[i]);
29 static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
33 for (i = 0; i < count; ++i)
34 if (__dcc_getstatus() & DCC_STATUS_RX)
35 buf[i] = __dcc_getchar();
42 static bool hvc_dcc_check(void)
44 unsigned long time = jiffies + (HZ / 10);
46 /* Write a test character to check if it is handled */
49 while (time_is_after_jiffies(time)) {
50 if (!(__dcc_getstatus() & DCC_STATUS_TX))
57 static const struct hv_ops hvc_dcc_get_put_ops = {
58 .get_chars = hvc_dcc_get_chars,
59 .put_chars = hvc_dcc_put_chars,
62 static int __init hvc_dcc_console_init(void)
69 /* Returns -1 if error */
70 ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
72 return ret < 0 ? -ENODEV : 0;
74 console_initcall(hvc_dcc_console_init);
76 static int __init hvc_dcc_init(void)
83 p = hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
85 return PTR_ERR_OR_ZERO(p);
87 device_initcall(hvc_dcc_init);