52 lines
1.1 KiB
C
52 lines
1.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2012 ARM Ltd.
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* Author: Marc Zyngier <marc.zyngier@arm.com>
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*
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* Adapted for ARM and earlycon:
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* Copyright (C) 2014 Linaro Ltd.
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* Author: Rob Herring <robh@kernel.org>
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*/
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#include <linux/kernel.h>
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#include <linux/console.h>
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#include <linux/init.h>
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#include <linux/serial_core.h>
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#ifdef CONFIG_THUMB2_KERNEL
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#define SEMIHOST_SWI "0xab"
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#else
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#define SEMIHOST_SWI "0x123456"
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#endif
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/*
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* Semihosting-based debug console
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*/
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static void smh_putc(struct uart_port *port, int c)
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{
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#ifdef CONFIG_ARM64
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asm volatile("mov x1, %0\n"
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"mov x0, #3\n"
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"hlt 0xf000\n"
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: : "r" (&c) : "x0", "x1", "memory");
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#else
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asm volatile("mov r1, %0\n"
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"mov r0, #3\n"
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"svc " SEMIHOST_SWI "\n"
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: : "r" (&c) : "r0", "r1", "memory");
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#endif
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}
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static void smh_write(struct console *con, const char *s, unsigned n)
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{
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struct earlycon_device *dev = con->data;
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uart_console_write(&dev->port, s, n, smh_putc);
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}
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static int
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__init early_smh_setup(struct earlycon_device *device, const char *opt)
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{
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device->con->write = smh_write;
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return 0;
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}
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EARLYCON_DECLARE(smh, early_smh_setup);
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