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363f66fe06
Recent changes to tighten the check for UARTs that don't correctly
re-assert THRE (01c194d927: "serial 8250:
tighten test for using backup timer") caused problems when such a UART was
opened for the second time - the bug could only successfully be detected
at first initialization. For users of this version of this particular
UART IP it is fatal.
This patch stores the information about the bug in the bugs field of the
port structure when the port is first started up so subsequent opens can
check this bit even if the test for the bug fails.
David Brownell: "My own exposure to this is that the UART on DaVinci
hardware, which TI allegedly derived from its original 16550 logic, has
periodically gone from working to unusable with the mainline 8250.c ...
and back and forth a bunch. Currently it's "unusable", a regression from
some previous versions. With this patch from Will, it's usable."
Signed-off-by: Will Newton <will.newton@gmail.com>
Acked-by: Alex Williamson <alex.williamson@hp.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Brownell <david-b@pacbell.net>
Cc: <stable@kernel.org> [2.6.26.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
80 lines
2.4 KiB
C
80 lines
2.4 KiB
C
/*
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* linux/drivers/char/8250.h
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*
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* Driver for 8250/16550-type serial ports
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*
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* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
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*
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* Copyright (C) 2001 Russell King.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/serial_8250.h>
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struct old_serial_port {
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unsigned int uart;
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unsigned int baud_base;
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unsigned int port;
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unsigned int irq;
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unsigned int flags;
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unsigned char hub6;
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unsigned char io_type;
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unsigned char *iomem_base;
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unsigned short iomem_reg_shift;
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};
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/*
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* This replaces serial_uart_config in include/linux/serial.h
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*/
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struct serial8250_config {
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const char *name;
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unsigned short fifo_size;
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unsigned short tx_loadsz;
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unsigned char fcr;
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unsigned int flags;
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};
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#define UART_CAP_FIFO (1 << 8) /* UART has FIFO */
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#define UART_CAP_EFR (1 << 9) /* UART has EFR */
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#define UART_CAP_SLEEP (1 << 10) /* UART has IER sleep */
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#define UART_CAP_AFE (1 << 11) /* MCR-based hw flow control */
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#define UART_CAP_UUE (1 << 12) /* UART needs IER bit 6 set (Xscale) */
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#define UART_BUG_QUOT (1 << 0) /* UART has buggy quot LSB */
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#define UART_BUG_TXEN (1 << 1) /* UART has buggy TX IIR status */
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#define UART_BUG_NOMSR (1 << 2) /* UART has buggy MSR status bits (Au1x00) */
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#define UART_BUG_THRE (1 << 3) /* UART has buggy THRE reassertion */
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#define PROBE_RSA (1 << 0)
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#define PROBE_ANY (~0)
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#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)
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#ifdef CONFIG_SERIAL_8250_SHARE_IRQ
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#define SERIAL8250_SHARE_IRQS 1
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#else
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#define SERIAL8250_SHARE_IRQS 0
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#endif
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#if defined(__alpha__) && !defined(CONFIG_PCI)
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/*
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* Digital did something really horribly wrong with the OUT1 and OUT2
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* lines on at least some ALPHA's. The failure mode is that if either
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* is cleared, the machine locks up with endless interrupts.
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*/
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#define ALPHA_KLUDGE_MCR (UART_MCR_OUT2 | UART_MCR_OUT1)
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#elif defined(CONFIG_SBC8560)
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/*
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* WindRiver did something similarly broken on their SBC8560 board. The
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* UART tristates its IRQ output while OUT2 is clear, but they pulled
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* the interrupt line _up_ instead of down, so if we register the IRQ
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* while the UART is in that state, we die in an IRQ storm. */
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#define ALPHA_KLUDGE_MCR (UART_MCR_OUT2)
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#else
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#define ALPHA_KLUDGE_MCR 0
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#endif
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