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When using no_console_suspend, the serial console may be powered off anyway during system sleep. Upon resume, the port may be in its default power-on state, but is expected to continue console i/o before the device has received its pm callback. The resultant garbage i/o can cause all kinds of havoc on the remote end. Use the scratch register as a canary to discover if the console has been powered-off. Write a non-zero value to the scratch register at port suspend and reprogram the port before any console i/o if the scratch register != canary before port resume. This workaround is disabled for omap_8250 (which uses different divisor programming). Credit to Doug Anderson <dianders@chromium.org> for the idea of using the scratch register canary to discover port power-down. Cc: Doug Anderson <dianders@chromium.org> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
144 lines
4.8 KiB
C
144 lines
4.8 KiB
C
/*
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* linux/include/linux/serial_8250.h
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*
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* Copyright (C) 2004 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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#ifndef _LINUX_SERIAL_8250_H
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#define _LINUX_SERIAL_8250_H
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#include <linux/serial_core.h>
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#include <linux/platform_device.h>
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/*
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* This is the platform device platform_data structure
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*/
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struct plat_serial8250_port {
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unsigned long iobase; /* io base address */
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void __iomem *membase; /* ioremap cookie or NULL */
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resource_size_t mapbase; /* resource base */
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unsigned int irq; /* interrupt number */
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unsigned long irqflags; /* request_irq flags */
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unsigned int uartclk; /* UART clock rate */
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void *private_data;
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unsigned char regshift; /* register shift */
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unsigned char iotype; /* UPIO_* */
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unsigned char hub6;
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upf_t flags; /* UPF_* flags */
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unsigned int type; /* If UPF_FIXED_TYPE */
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unsigned int (*serial_in)(struct uart_port *, int);
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void (*serial_out)(struct uart_port *, int, int);
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void (*set_termios)(struct uart_port *,
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struct ktermios *new,
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struct ktermios *old);
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int (*handle_irq)(struct uart_port *);
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void (*pm)(struct uart_port *, unsigned int state,
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unsigned old);
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void (*handle_break)(struct uart_port *);
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};
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/*
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* Allocate 8250 platform device IDs. Nothing is implied by
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* the numbering here, except for the legacy entry being -1.
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*/
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enum {
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PLAT8250_DEV_LEGACY = -1,
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PLAT8250_DEV_PLATFORM,
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PLAT8250_DEV_PLATFORM1,
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PLAT8250_DEV_PLATFORM2,
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PLAT8250_DEV_FOURPORT,
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PLAT8250_DEV_ACCENT,
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PLAT8250_DEV_BOCA,
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PLAT8250_DEV_EXAR_ST16C554,
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PLAT8250_DEV_HUB6,
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PLAT8250_DEV_AU1X00,
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PLAT8250_DEV_SM501,
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};
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struct uart_8250_dma;
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/*
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* This should be used by drivers which want to register
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* their own 8250 ports without registering their own
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* platform device. Using these will make your driver
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* dependent on the 8250 driver.
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*/
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struct uart_8250_port {
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struct uart_port port;
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struct timer_list timer; /* "no irq" timer */
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struct list_head list; /* ports on this IRQ */
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unsigned short capabilities; /* port capabilities */
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unsigned short bugs; /* port bugs */
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bool fifo_bug; /* min RX trigger if enabled */
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unsigned int tx_loadsz; /* transmit fifo load size */
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unsigned char acr;
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unsigned char fcr;
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unsigned char ier;
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unsigned char lcr;
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unsigned char mcr;
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unsigned char mcr_mask; /* mask of user bits */
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unsigned char mcr_force; /* mask of forced bits */
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unsigned char cur_iotype; /* Running I/O type */
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unsigned int rpm_tx_active;
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unsigned char canary; /* non-zero during system sleep
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* if no_console_suspend
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*/
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/*
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* Some bits in registers are cleared on a read, so they must
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* be saved whenever the register is read but the bits will not
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* be immediately processed.
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*/
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#define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
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unsigned char lsr_saved_flags;
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#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
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unsigned char msr_saved_flags;
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struct uart_8250_dma *dma;
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/* 8250 specific callbacks */
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int (*dl_read)(struct uart_8250_port *);
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void (*dl_write)(struct uart_8250_port *, int);
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};
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static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
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{
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return container_of(up, struct uart_8250_port, port);
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}
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int serial8250_register_8250_port(struct uart_8250_port *);
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void serial8250_unregister_port(int line);
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void serial8250_suspend_port(int line);
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void serial8250_resume_port(int line);
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extern int early_serial_setup(struct uart_port *port);
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extern int serial8250_find_port(struct uart_port *p);
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extern int serial8250_find_port_for_earlycon(void);
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extern unsigned int serial8250_early_in(struct uart_port *port, int offset);
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extern void serial8250_early_out(struct uart_port *port, int offset, int value);
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extern int setup_early_serial8250_console(char *cmdline);
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extern void serial8250_do_set_termios(struct uart_port *port,
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struct ktermios *termios, struct ktermios *old);
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extern int serial8250_do_startup(struct uart_port *port);
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extern void serial8250_do_shutdown(struct uart_port *port);
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extern void serial8250_do_pm(struct uart_port *port, unsigned int state,
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unsigned int oldstate);
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extern void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl);
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extern int fsl8250_handle_irq(struct uart_port *port);
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int serial8250_handle_irq(struct uart_port *port, unsigned int iir);
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unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr);
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void serial8250_tx_chars(struct uart_8250_port *up);
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unsigned int serial8250_modem_status(struct uart_8250_port *up);
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extern void serial8250_set_isa_configurator(void (*v)
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(int port, struct uart_port *up,
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unsigned short *capabilities));
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#endif
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