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aef9a7bd9b
Add tunable RX interrupt trigger I/F of FIFO buffers.
Serial devices are used as not only message communication devices but control
or sending communication devices. For the latter uses, normally small data
will be exchanged, so user applications want to receive data unit as soon as
possible for real-time tendency. If we have a sensor which sends a 1 byte data
each time and must control a device based on the sensor feedback, the RX
interrupt should be triggered for each data.
According to HW specification of serial UART devices, RX interrupt trigger
can be changed, but the trigger is hard-coded. For example, RX interrupt trigger
in 16550A can be set to 1, 4, 8, or 14 bytes for HW, but current driver sets
the trigger to only 8bytes.
This patch makes some devices change RX interrupt trigger from userland.
<How to use>
- Read current setting
# cat /sys/class/tty/ttyS0/rx_trig_bytes
8
- Write user setting
# echo 1 > /sys/class/tty/ttyS0/rx_trig_bytes
# cat /sys/class/tty/ttyS0/rx_trig_bytes
1
<Support uart devices>
- 16550A and Tegra (1, 4, 8, or 14 bytes)
- 16650V2 (8, 16, 24, or 28 bytes)
- 16654 (8, 16, 56, or 60 bytes)
- 16750 (1, 16, 32, or 56 bytes)
<Change log>
Changes in V9:
- Use attr_group instead of dev_spec_attr_group of uart_port structure
Changes in V8:
- Divide this patch from V7's patch based on Greg's comment
Changes in V7:
- Add Documentation
- Change I/F name from rx_int_trig to rx_trig_bytes because the name
rx_int_trig is hard to understand how users specify the value
Changes in V6:
- Move FCR_RX_TRIG_* definition in 8250.h to include/uapi/linux/serial_reg.h,
rename those to UART_FCR_R_TRIG_*, and use UART_FCR_TRIGGER_MASK to
UART_FCR_R_TRIG_BITS()
- Change following function names:
convert_fcr2val() => fcr_get_rxtrig_bytes()
convert_val2rxtrig() => bytes_to_fcr_rxtrig()
- Fix typo in serial8250_do_set_termios()
- Delete the verbose error message pr_info() in bytes_to_fcr_rxtrig()
- Rename *rx_int_trig/rx_trig* to *rxtrig* for several functions or variables
(but UI remains rx_int_trig)
- Change the meaningless variable name 'val' to 'bytes' following functions:
fcr_get_rxtrig_bytes(), bytes_to_fcr_rxtrig(), do_set_rxtrig(),
do_serial8250_set_rxtrig(), and serial8250_set_attr_rxtrig()
- Use up->fcr in order to get rxtrig_bytes instead of rx_trig_raw in
fcr_get_rxtrig_bytes()
- Use conf_type->rxtrig_bytes[0] instead of switch statement for support check
in register_dev_spec_attr_grp()
- Delete the checking whether a user changed FCR or not when minimum buffer
is needed in serial8250_do_set_termios()
Changes in V5.1:
- Fix FCR_RX_TRIG_MAX_STATE definition
Changes in V5:
- Support Tegra, 16650V2, 16654, and 16750
- Store default FCR value to up->fcr when the port is first created
- Add rx_trig_byte[] in uart_config[] for each device and use rx_trig_byte[]
in convert_fcr2val() and convert_val2rxtrig()
Changes in V4:
- Introduce fifo_bug flag in uart_8250_port structure
This is enabled only when parity is enabled and UART_BUG_PARITY is enabled
for up->bugs. If this flag is enabled, user cannot set RX trigger.
- Return -EOPNOTSUPP when it does not support device at convert_fcr2val() and
at convert_val2rxtrig()
- Set the nearest lower RX trigger when users input a meaningless value at
convert_val2rxtrig()
- Check whether p->fcr is existing at serial8250_clear_and_reinit_fifos()
- Set fcr = up->fcr in the begging of serial8250_do_set_termios()
Changes in V3:
- Change I/F from ioctl(2) to sysfs(rx_int_trig)
Changed in V2:
- Use _IOW for TIOCSFIFORTRIG definition
- Pass the interrupt trigger value itself
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
137 lines
4.4 KiB
C
137 lines
4.4 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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/*
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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 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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