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2874c5fd28
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
100 lines
2.1 KiB
C
100 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* A udbg backend which logs messages and reads input from in memory
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* buffers.
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*
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* The console output can be read from memcons_output which is a
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* circular buffer whose next write position is stored in memcons.output_pos.
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*
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* Input may be passed by writing into the memcons_input buffer when it is
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* empty. The input buffer is empty when both input_pos == input_start and
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* *input_start == '\0'.
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*
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* Copyright (C) 2003-2005 Anton Blanchard and Milton Miller, IBM Corp
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* Copyright (C) 2013 Alistair Popple, IBM Corp
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*/
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#include <linux/kernel.h>
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#include <asm/barrier.h>
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#include <asm/page.h>
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#include <asm/processor.h>
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#include <asm/udbg.h>
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struct memcons {
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char *output_start;
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char *output_pos;
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char *output_end;
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char *input_start;
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char *input_pos;
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char *input_end;
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};
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static char memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE];
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static char memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE];
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struct memcons memcons = {
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.output_start = memcons_output,
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.output_pos = memcons_output,
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.output_end = &memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE],
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.input_start = memcons_input,
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.input_pos = memcons_input,
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.input_end = &memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE],
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};
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void memcons_putc(char c)
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{
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char *new_output_pos;
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*memcons.output_pos = c;
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wmb();
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new_output_pos = memcons.output_pos + 1;
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if (new_output_pos >= memcons.output_end)
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new_output_pos = memcons.output_start;
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memcons.output_pos = new_output_pos;
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}
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int memcons_getc_poll(void)
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{
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char c;
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char *new_input_pos;
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if (*memcons.input_pos) {
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c = *memcons.input_pos;
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new_input_pos = memcons.input_pos + 1;
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if (new_input_pos >= memcons.input_end)
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new_input_pos = memcons.input_start;
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else if (*new_input_pos == '\0')
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new_input_pos = memcons.input_start;
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*memcons.input_pos = '\0';
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wmb();
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memcons.input_pos = new_input_pos;
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return c;
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}
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return -1;
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}
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int memcons_getc(void)
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{
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int c;
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while (1) {
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c = memcons_getc_poll();
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if (c == -1)
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cpu_relax();
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else
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break;
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}
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return c;
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}
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void udbg_init_memcons(void)
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{
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udbg_putc = memcons_putc;
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udbg_getc = memcons_getc;
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udbg_getc_poll = memcons_getc_poll;
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}
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