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d74d5d1b72
While comparing the OMAP-serial and the 8250 part of this I noticed that the latter does not use run time-pm. Here are the pieces. It is basically a get before first register access and a last_busy + put after last access. This has to be enabled from userland _and_ UART_CAP_RPM is required for this. The runtime PM can usually work transparently in the background however there is one exception to this: After serial8250_tx_chars() completes there still may be unsent bytes in the FIFO (depending on CPU speed vs baud rate + flow control). Even if the TTY-buffer is empty we do not want RPM to disable the device because it won't send the remaining bytes. Instead we leave serial8250_tx_chars() with RPM enabled and wait for the FIFO empty interrupt. Once we enter serial8250_tx_chars() with an empty buffer we know that the FIFO is empty and since we are not going to send anything, we can disable the device. That xchg() is to ensure that serial8250_tx_chars() can be called multiple times and only the first invocation will actually invoke the runtime PM function. So that the last invocation of __stop_tx() will disable runtime pm. NOTE: do not enable RPM on the device unless you know what you do! If the device goes idle, it won't be woken up by incomming RX data _unless_ there is a wakeup irq configured which is usually the RX pin configure for wakeup via the reset module. The RX activity will then wake up the device from idle. However the first character is garbage and lost. The following bytes will be received once the device is up in time. On the beagle board xm (omap3) it takes approx 13ms from the first wakeup byte until the first byte that is received properly if the device was in core-off. v5…v8: - drop RPM from serial8250_set_mctrl() it will be used in restore path which already has RPM active and holds dev->power.lock v4…v5: - add a wrapper around rpm function and introduce UART_CAP_RPM to ensure RPM put is invoked after the TX FIFO is empty. v3…v4: - added runtime to the console code - removed device_may_wakeup() from serial8250_set_sleep() Cc: mika.westerberg@linux.intel.com Reviewed-by: Tony Lindgren <tony@atomide.com> Tested-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
143 lines
4.7 KiB
C
143 lines
4.7 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 char rpm_tx_active;
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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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struct serial_rs485 rs485;
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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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int (*rs485_config)(struct uart_8250_port *,
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struct serial_rs485 *rs485);
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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 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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