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/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/types.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 inline u32 __dcc_getstatus(void)
{
u32 __ret;
asm volatile("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg"
: "=r" (__ret) : : "cc");
return __ret;
}
static inline char __dcc_getchar(void)
{
char __c;
asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg"
: "=r" (__c));
isb();
return __c;
}
static inline void __dcc_putchar(char c)
{
asm volatile("mcr p14, 0, %0, c0, c5, 0 @ write a char"
: /* no output register */
: "r" (c));
isb();
}
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)
{
if (!hvc_dcc_check())
return -ENODEV;
hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
return 0;
}
console_initcall(hvc_dcc_console_init);
static int __init hvc_dcc_init(void)
{
if (!hvc_dcc_check())
return -ENODEV;
hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
return 0;
}
device_initcall(hvc_dcc_init);
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