forked from Minki/linux
hvc: dcc: Add earlycon support
Add DCC earlycon support for early printks. The patch is useful for SoC bringup where HW serial console is broken. Signed-off-by: Michal Simek <michal.simek@xilinx.com> Link: https://lore.kernel.org/r/41e2920a6348e65b2e986b0e65b66531e87cd756.1570543923.git.michal.simek@xilinx.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1,7 +1,10 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved. */
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#include <linux/console.h>
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#include <linux/init.h>
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#include <linux/serial.h>
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#include <linux/serial_core.h>
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#include <asm/dcc.h>
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#include <asm/processor.h>
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@ -12,6 +15,31 @@
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#define DCC_STATUS_RX (1 << 30)
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#define DCC_STATUS_TX (1 << 29)
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static void dcc_uart_console_putchar(struct uart_port *port, int ch)
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{
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while (__dcc_getstatus() & DCC_STATUS_TX)
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cpu_relax();
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__dcc_putchar(ch);
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}
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static void dcc_early_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, dcc_uart_console_putchar);
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}
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static int __init dcc_early_console_setup(struct earlycon_device *device,
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const char *opt)
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{
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device->con->write = dcc_early_write;
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return 0;
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}
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EARLYCON_DECLARE(dcc, dcc_early_console_setup);
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static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
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{
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int i;
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