Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * A udbg backend which logs messages and reads input from in memory
 * buffers.
 *
 * The console output can be read from memcons_output which is a
 * circular buffer whose next write position is stored in memcons.output_pos.
 *
 * Input may be passed by writing into the memcons_input buffer when it is
 * empty. The input buffer is empty when both input_pos == input_start and
 * *input_start == '\0'.
 *
 * Copyright (C) 2003-2005 Anton Blanchard and Milton Miller, IBM Corp
 * Copyright (C) 2013 Alistair Popple, IBM Corp
 */
 
#include <linux/kernel.h>
#include <asm/barrier.h>
#include <asm/page.h>
#include <asm/processor.h>
#include <asm/udbg.h>
 
struct memcons {
<------>char *output_start;
<------>char *output_pos;
<------>char *output_end;
<------>char *input_start;
<------>char *input_pos;
<------>char *input_end;
};
 
static char memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE];
static char memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE];
 
struct memcons memcons = {
<------>.output_start = memcons_output,
<------>.output_pos = memcons_output,
<------>.output_end = &memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE],
<------>.input_start = memcons_input,
<------>.input_pos = memcons_input,
<------>.input_end = &memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE],
};
 
void memcons_putc(char c)
{
<------>char *new_output_pos;
 
<------>*memcons.output_pos = c;
<------>wmb();
<------>new_output_pos = memcons.output_pos + 1;
<------>if (new_output_pos >= memcons.output_end)
<------><------>new_output_pos = memcons.output_start;
 
<------>memcons.output_pos = new_output_pos;
}
 
int memcons_getc_poll(void)
{
<------>char c;
<------>char *new_input_pos;
 
<------>if (*memcons.input_pos) {
<------><------>c = *memcons.input_pos;
 
<------><------>new_input_pos = memcons.input_pos + 1;
<------><------>if (new_input_pos >= memcons.input_end)
<------><------><------>new_input_pos = memcons.input_start;
<------><------>else if (*new_input_pos == '\0')
<------><------><------>new_input_pos = memcons.input_start;
 
<------><------>*memcons.input_pos = '\0';
<------><------>wmb();
<------><------>memcons.input_pos = new_input_pos;
<------><------>return c;
<------>}
 
<------>return -1;
}
 
int memcons_getc(void)
{
<------>int c;
 
<------>while (1) {
<------><------>c = memcons_getc_poll();
<------><------>if (c == -1)
<------><------><------>cpu_relax();
<------><------>else
<------><------><------>break;
<------>}
 
<------>return c;
}
 
void udbg_init_memcons(void)
{
<------>udbg_putc = memcons_putc;
<------>udbg_getc = memcons_getc;
<------>udbg_getc_poll = memcons_getc_poll;
}