diff options
Diffstat (limited to 'Documentation/serial')
| -rw-r--r-- | Documentation/serial/00-INDEX | 16 | ||||
| -rw-r--r-- | Documentation/serial/README.cycladesZ | 8 | ||||
| -rw-r--r-- | Documentation/serial/driver | 486 | ||||
| -rw-r--r-- | Documentation/serial/moxa-smartio | 523 | ||||
| -rw-r--r-- | Documentation/serial/n_gsm.txt | 96 | ||||
| -rw-r--r-- | Documentation/serial/rocket.txt | 189 | ||||
| -rw-r--r-- | Documentation/serial/serial-rs485.txt | 95 | ||||
| -rw-r--r-- | Documentation/serial/tty.txt | 313 |
8 files changed, 1726 insertions, 0 deletions
diff --git a/Documentation/serial/00-INDEX b/Documentation/serial/00-INDEX new file mode 100644 index 000000000..8021a9f29 --- /dev/null +++ b/Documentation/serial/00-INDEX @@ -0,0 +1,16 @@ +00-INDEX + - this file. +README.cycladesZ + - info on Cyclades-Z firmware loading. +driver + - intro to the low level serial driver. +moxa-smartio + - file with info on installing/using Moxa multiport serial driver. +n_gsm.txt + - GSM 0710 tty multiplexer howto. +rocket.txt + - info on the Comtrol RocketPort multiport serial driver. +serial-rs485.txt + - info about RS485 structures and support in the kernel. +tty.txt + - guide to the locking policies of the tty layer. diff --git a/Documentation/serial/README.cycladesZ b/Documentation/serial/README.cycladesZ new file mode 100644 index 000000000..024a69443 --- /dev/null +++ b/Documentation/serial/README.cycladesZ @@ -0,0 +1,8 @@ + +The Cyclades-Z must have firmware loaded onto the card before it will +operate. This operation should be performed during system startup, + +The firmware, loader program and the latest device driver code are +available from Cyclades at + ftp://ftp.cyclades.com/pub/cyclades/cyclades-z/linux/ + diff --git a/Documentation/serial/driver b/Documentation/serial/driver new file mode 100644 index 000000000..da193e092 --- /dev/null +++ b/Documentation/serial/driver @@ -0,0 +1,486 @@ + + Low Level Serial API + -------------------- + + +This document is meant as a brief overview of some aspects of the new serial +driver. It is not complete, any questions you have should be directed to +<rmk@arm.linux.org.uk> + +The reference implementation is contained within amba_pl011.c. + + + +Low Level Serial Hardware Driver +-------------------------------- + +The low level serial hardware driver is responsible for supplying port +information (defined by uart_port) and a set of control methods (defined +by uart_ops) to the core serial driver. The low level driver is also +responsible for handling interrupts for the port, and providing any +console support. + + +Console Support +--------------- + +The serial core provides a few helper functions. This includes identifing +the correct port structure (via uart_get_console) and decoding command line +arguments (uart_parse_options). + +There is also a helper function (uart_console_write) which performs a +character by character write, translating newlines to CRLF sequences. +Driver writers are recommended to use this function rather than implementing +their own version. + + +Locking +------- + +It is the responsibility of the low level hardware driver to perform the +necessary locking using port->lock. There are some exceptions (which +are described in the uart_ops listing below.) + +There are two locks. A per-port spinlock, and an overall semaphore. + +From the core driver perspective, the port->lock locks the following +data: + + port->mctrl + port->icount + port->state->xmit.head (circ_buf->head) + port->state->xmit.tail (circ_buf->tail) + +The low level driver is free to use this lock to provide any additional +locking. + +The port_sem semaphore is used to protect against ports being added/ +removed or reconfigured at inappropriate times. Since v2.6.27, this +semaphore has been the 'mutex' member of the tty_port struct, and +commonly referred to as the port mutex. + + +uart_ops +-------- + +The uart_ops structure is the main interface between serial_core and the +hardware specific driver. It contains all the methods to control the +hardware. + + tx_empty(port) + This function tests whether the transmitter fifo and shifter + for the port described by 'port' is empty. If it is empty, + this function should return TIOCSER_TEMT, otherwise return 0. + If the port does not support this operation, then it should + return TIOCSER_TEMT. + + Locking: none. + Interrupts: caller dependent. + This call must not sleep + + set_mctrl(port, mctrl) + This function sets the modem control lines for port described + by 'port' to the state described by mctrl. The relevant bits + of mctrl are: + - TIOCM_RTS RTS signal. + - TIOCM_DTR DTR signal. + - TIOCM_OUT1 OUT1 signal. + - TIOCM_OUT2 OUT2 signal. + - TIOCM_LOOP Set the port into loopback mode. + If the appropriate bit is set, the signal should be driven + active. If the bit is clear, the signal should be driven + inactive. + + Locking: port->lock taken. + Interrupts: locally disabled. + This call must not sleep + + get_mctrl(port) + Returns the current state of modem control inputs. The state + of the outputs should not be returned, since the core keeps + track of their state. The state information should include: + - TIOCM_CAR state of DCD signal + - TIOCM_CTS state of CTS signal + - TIOCM_DSR state of DSR signal + - TIOCM_RI state of RI signal + The bit is set if the signal is currently driven active. If + the port does not support CTS, DCD or DSR, the driver should + indicate that the signal is permanently active. If RI is + not available, the signal should not be indicated as active. + + Locking: port->lock taken. + Interrupts: locally disabled. + This call must not sleep + + stop_tx(port) + Stop transmitting characters. This might be due to the CTS + line becoming inactive or the tty layer indicating we want + to stop transmission due to an XOFF character. + + The driver should stop transmitting characters as soon as + possible. + + Locking: port->lock taken. + Interrupts: locally disabled. + This call must not sleep + + start_tx(port) + Start transmitting characters. + + Locking: port->lock taken. + Interrupts: locally disabled. + This call must not sleep + + throttle(port) + Notify the serial driver that input buffers for the line discipline are + close to full, and it should somehow signal that no more characters + should be sent to the serial port. + This will be called only if hardware assisted flow control is enabled. + + Locking: serialized with .unthrottle() and termios modification by the + tty layer. + + unthrottle(port) + Notify the serial driver that characters can now be sent to the serial + port without fear of overrunning the input buffers of the line + disciplines. + This will be called only if hardware assisted flow control is enabled. + + Locking: serialized with .throttle() and termios modification by the + tty layer. + + send_xchar(port,ch) + Transmit a high priority character, even if the port is stopped. + This is used to implement XON/XOFF flow control and tcflow(). If + the serial driver does not implement this function, the tty core + will append the character to the circular buffer and then call + start_tx() / stop_tx() to flush the data out. + + Do not transmit if ch == '\0' (__DISABLED_CHAR). + + Locking: none. + Interrupts: caller dependent. + + stop_rx(port) + Stop receiving characters; the port is in the process of + being closed. + + Locking: port->lock taken. + Interrupts: locally disabled. + This call must not sleep + + enable_ms(port) + Enable the modem status interrupts. + + This method may be called multiple times. Modem status + interrupts should be disabled when the shutdown method is + called. + + Locking: port->lock taken. + Interrupts: locally disabled. + This call must not sleep + + break_ctl(port,ctl) + Control the transmission of a break signal. If ctl is + nonzero, the break signal should be transmitted. The signal + should be terminated when another call is made with a zero + ctl. + + Locking: caller holds tty_port->mutex + + startup(port) + Grab any interrupt resources and initialise any low level driver + state. Enable the port for reception. It should not activate + RTS nor DTR; this will be done via a separate call to set_mctrl. + + This method will only be called when the port is initially opened. + + Locking: port_sem taken. + Interrupts: globally disabled. + + shutdown(port) + Disable the port, disable any break condition that may be in + effect, and free any interrupt resources. It should not disable + RTS nor DTR; this will have already been done via a separate + call to set_mctrl. + + Drivers must not access port->state once this call has completed. + + This method will only be called when there are no more users of + this port. + + Locking: port_sem taken. + Interrupts: caller dependent. + + flush_buffer(port) + Flush any write buffers, reset any DMA state and stop any + ongoing DMA transfers. + + This will be called whenever the port->state->xmit circular + buffer is cleared. + + Locking: port->lock taken. + Interrupts: locally disabled. + This call must not sleep + + set_termios(port,termios,oldtermios) + Change the port parameters, including word length, parity, stop + bits. Update read_status_mask and ignore_status_mask to indicate + the types of events we are interested in receiving. Relevant + termios->c_cflag bits are: + CSIZE - word size + CSTOPB - 2 stop bits + PARENB - parity enable + PARODD - odd parity (when PARENB is in force) + CREAD - enable reception of characters (if not set, + still receive characters from the port, but + throw them away. + CRTSCTS - if set, enable CTS status change reporting + CLOCAL - if not set, enable modem status change + reporting. + Relevant termios->c_iflag bits are: + INPCK - enable frame and parity error events to be + passed to the TTY layer. + BRKINT + PARMRK - both of these enable break events to be + passed to the TTY layer. + + IGNPAR - ignore parity and framing errors + IGNBRK - ignore break errors, If IGNPAR is also + set, ignore overrun errors as well. + The interaction of the iflag bits is as follows (parity error + given as an example): + Parity error INPCK IGNPAR + n/a 0 n/a character received, marked as + TTY_NORMAL + None 1 n/a character received, marked as + TTY_NORMAL + Yes 1 0 character received, marked as + TTY_PARITY + Yes 1 1 character discarded + + Other flags may be used (eg, xon/xoff characters) if your + hardware supports hardware "soft" flow control. + + Locking: caller holds tty_port->mutex + Interrupts: caller dependent. + This call must not sleep + + set_ldisc(port,termios) + Notifier for discipline change. See Documentation/serial/tty.txt. + + Locking: caller holds tty_port->mutex + + pm(port,state,oldstate) + Perform any power management related activities on the specified + port. State indicates the new state (defined by + enum uart_pm_state), oldstate indicates the previous state. + + This function should not be used to grab any resources. + + This will be called when the port is initially opened and finally + closed, except when the port is also the system console. This + will occur even if CONFIG_PM is not set. + + Locking: none. + Interrupts: caller dependent. + + type(port) + Return a pointer to a string constant describing the specified + port, or return NULL, in which case the string 'unknown' is + substituted. + + Locking: none. + Interrupts: caller dependent. + + release_port(port) + Release any memory and IO region resources currently in use by + the port. + + Locking: none. + Interrupts: caller dependent. + + request_port(port) + Request any memory and IO region resources required by the port. + If any fail, no resources should be registered when this function + returns, and it should return -EBUSY on failure. + + Locking: none. + Interrupts: caller dependent. + + config_port(port,type) + Perform any autoconfiguration steps required for the port. `type` + contains a bit mask of the required configuration. UART_CONFIG_TYPE + indicates that the port requires detection and identification. + port->type should be set to the type found, or PORT_UNKNOWN if + no port was detected. + + UART_CONFIG_IRQ indicates autoconfiguration of the interrupt signal, + which should be probed using standard kernel autoprobing techniques. + This is not necessary on platforms where ports have interrupts + internally hard wired (eg, system on a chip implementations). + + Locking: none. + Interrupts: caller dependent. + + verify_port(port,serinfo) + Verify the new serial port information contained within serinfo is + suitable for this port type. + + Locking: none. + Interrupts: caller dependent. + + ioctl(port,cmd,arg) + Perform any port specific IOCTLs. IOCTL commands must be defined + using the standard numbering system found in <asm/ioctl.h> + + Locking: none. + Interrupts: caller dependent. + + poll_init(port) + Called by kgdb to perform the minimal hardware initialization needed + to support poll_put_char() and poll_get_char(). Unlike ->startup() + this should not request interrupts. + + Locking: tty_mutex and tty_port->mutex taken. + Interrupts: n/a. + + poll_put_char(port,ch) + Called by kgdb to write a single character directly to the serial + port. It can and should block until there is space in the TX FIFO. + + Locking: none. + Interrupts: caller dependent. + This call must not sleep + + poll_get_char(port) + Called by kgdb to read a single character directly from the serial + port. If data is available, it should be returned; otherwise + the function should return NO_POLL_CHAR immediately. + + Locking: none. + Interrupts: caller dependent. + This call must not sleep + +Other functions +--------------- + +uart_update_timeout(port,cflag,baud) + Update the FIFO drain timeout, port->timeout, according to the + number of bits, parity, stop bits and baud rate. + + Locking: caller is expected to take port->lock + Interrupts: n/a + +uart_get_baud_rate(port,termios,old,min,max) + Return the numeric baud rate for the specified termios, taking + account of the special 38400 baud "kludge". The B0 baud rate + is mapped to 9600 baud. + + If the baud rate is not within min..max, then if old is non-NULL, + the original baud rate will be tried. If that exceeds the + min..max constraint, 9600 baud will be returned. termios will + be updated to the baud rate in use. + + Note: min..max must always allow 9600 baud to be selected. + + Locking: caller dependent. + Interrupts: n/a + +uart_get_divisor(port,baud) + Return the divisor (baud_base / baud) for the specified baud + rate, appropriately rounded. + + If 38400 baud and custom divisor is selected, return the + custom divisor instead. + + Locking: caller dependent. + Interrupts: n/a + +uart_match_port(port1,port2) + This utility function can be used to determine whether two + uart_port structures describe the same port. + + Locking: n/a + Interrupts: n/a + +uart_write_wakeup(port) + A driver is expected to call this function when the number of + characters in the transmit buffer have dropped below a threshold. + + Locking: port->lock should be held. + Interrupts: n/a + +uart_register_driver(drv) + Register a uart driver with the core driver. We in turn register + with the tty layer, and initialise the core driver per-port state. + + drv->port should be NULL, and the per-port structures should be + registered using uart_add_one_port after this call has succeeded. + + Locking: none + Interrupts: enabled + +uart_unregister_driver() + Remove all references to a driver from the core driver. The low + level driver must have removed all its ports via the + uart_remove_one_port() if it registered them with uart_add_one_port(). + + Locking: none + Interrupts: enabled + +uart_suspend_port() + +uart_resume_port() + +uart_add_one_port() + +uart_remove_one_port() + +Other notes +----------- + +It is intended some day to drop the 'unused' entries from uart_port, and +allow low level drivers to register their own individual uart_port's with +the core. This will allow drivers to use uart_port as a pointer to a +structure containing both the uart_port entry with their own extensions, +thus: + + struct my_port { + struct uart_port port; + int my_stuff; + }; + +Modem control lines via GPIO +---------------------------- + +Some helpers are provided in order to set/get modem control lines via GPIO. + +mctrl_gpio_init(port, idx): + This will get the {cts,rts,...}-gpios from device tree if they are + present and request them, set direction etc, and return an + allocated structure. devm_* functions are used, so there's no need + to call mctrl_gpio_free(). + As this sets up the irq handling make sure to not handle changes to the + gpio input lines in your driver, too. + +mctrl_gpio_free(dev, gpios): + This will free the requested gpios in mctrl_gpio_init(). + As devm_* functions are used, there's generally no need to call + this function. + +mctrl_gpio_to_gpiod(gpios, gidx) + This returns the gpio_desc structure associated to the modem line + index. + +mctrl_gpio_set(gpios, mctrl): + This will sets the gpios according to the mctrl state. + +mctrl_gpio_get(gpios, mctrl): + This will update mctrl with the gpios values. + +mctrl_gpio_enable_ms(gpios): + Enables irqs and handling of changes to the ms lines. + +mctrl_gpio_disable_ms(gpios): + Disables irqs and handling of changes to the ms lines. diff --git a/Documentation/serial/moxa-smartio b/Documentation/serial/moxa-smartio new file mode 100644 index 000000000..5d2a33be0 --- /dev/null +++ b/Documentation/serial/moxa-smartio @@ -0,0 +1,523 @@ +============================================================================= + MOXA Smartio/Industio Family Device Driver Installation Guide + for Linux Kernel 2.4.x, 2.6.x + Copyright (C) 2008, Moxa Inc. +============================================================================= +Date: 01/21/2008 + +Content + +1. Introduction +2. System Requirement +3. Installation + 3.1 Hardware installation + 3.2 Driver files + 3.3 Device naming convention + 3.4 Module driver configuration + 3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x. + 3.6 Custom configuration + 3.7 Verify driver installation +4. Utilities +5. Setserial +6. Troubleshooting + +----------------------------------------------------------------------------- +1. Introduction + + The Smartio/Industio/UPCI family Linux driver supports following multiport + boards. + + - 2 ports multiport board + CP-102U, CP-102UL, CP-102UF + CP-132U-I, CP-132UL, + CP-132, CP-132I, CP132S, CP-132IS, + CI-132, CI-132I, CI-132IS, + (C102H, C102HI, C102HIS, C102P, CP-102, CP-102S) + + - 4 ports multiport board + CP-104EL, + CP-104UL, CP-104JU, + CP-134U, CP-134U-I, + C104H/PCI, C104HS/PCI, + CP-114, CP-114I, CP-114S, CP-114IS, CP-114UL, + C104H, C104HS, + CI-104J, CI-104JS, + CI-134, CI-134I, CI-134IS, + (C114HI, CT-114I, C104P) + POS-104UL, + CB-114, + CB-134I + + - 8 ports multiport board + CP-118EL, CP-168EL, + CP-118U, CP-168U, + C168H/PCI, + C168H, C168HS, + (C168P), + CB-108 + + This driver and installation procedure have been developed upon Linux Kernel + 2.4.x and 2.6.x. This driver supports Intel x86 hardware platform. In order + to maintain compatibility, this version has also been properly tested with + RedHat, Mandrake, Fedora and S.u.S.E Linux. However, if compatibility problem + occurs, please contact Moxa at support@moxa.com.tw. + + In addition to device driver, useful utilities are also provided in this + version. They are + - msdiag Diagnostic program for displaying installed Moxa + Smartio/Industio boards. + - msmon Monitor program to observe data count and line status signals. + - msterm A simple terminal program which is useful in testing serial + ports. + - io-irq.exe Configuration program to setup ISA boards. Please note that + this program can only be executed under DOS. + + All the drivers and utilities are published in form of source code under + GNU General Public License in this version. Please refer to GNU General + Public License announcement in each source code file for more detail. + + In Moxa's Web sites, you may always find latest driver at http://www.moxa.com/. + + This version of driver can be installed as Loadable Module (Module driver) + or built-in into kernel (Static driver). You may refer to following + installation procedure for suitable one. Before you install the driver, + please refer to hardware installation procedure in the User's Manual. + + We assume the user should be familiar with following documents. + - Serial-HOWTO + - Kernel-HOWTO + +----------------------------------------------------------------------------- +2. System Requirement + - Hardware platform: Intel x86 machine + - Kernel version: 2.4.x or 2.6.x + - gcc version 2.72 or later + - Maximum 4 boards can be installed in combination + +----------------------------------------------------------------------------- +3. Installation + + 3.1 Hardware installation + 3.2 Driver files + 3.3 Device naming convention + 3.4 Module driver configuration + 3.5 Static driver configuration for Linux kernel 2.4.x, 2.6.x. + 3.6 Custom configuration + 3.7 Verify driver installation + + + 3.1 Hardware installation + + There are two types of buses, ISA and PCI, for Smartio/Industio + family multiport board. + + ISA board + --------- + You'll have to configure CAP address, I/O address, Interrupt Vector + as well as IRQ before installing this driver. Please refer to hardware + installation procedure in User's Manual before proceed any further. + Please make sure the JP1 is open after the ISA board is set properly. + + PCI/UPCI board + -------------- + You may need to adjust IRQ usage in BIOS to avoid from IRQ conflict + with other ISA devices. Please refer to hardware installation + procedure in User's Manual in advance. + + PCI IRQ Sharing + ----------- + Each port within the same multiport board shares the same IRQ. Up to + 4 Moxa Smartio/Industio PCI Family multiport boards can be installed + together on one system and they can share the same IRQ. + + + 3.2 Driver files + + The driver file may be obtained from ftp, CD-ROM or floppy disk. The + first step, anyway, is to copy driver file "mxser.tgz" into specified + directory. e.g. /moxa. The execute commands as below. + + # cd / + # mkdir moxa + # cd /moxa + # tar xvf /dev/fd0 + + or + + # cd / + # mkdir moxa + # cd /moxa + # cp /mnt/cdrom/<driver directory>/mxser.tgz . + # tar xvfz mxser.tgz + + + 3.3 Device naming convention + + You may find all the driver and utilities files in /moxa/mxser. + Following installation procedure depends on the model you'd like to + run the driver. If you prefer module driver, please refer to 3.4. + If static driver is required, please refer to 3.5. + + Dialin and callout port + ----------------------- + This driver remains traditional serial device properties. There are + two special file name for each serial port. One is dial-in port + which is named "ttyMxx". For callout port, the naming convention + is "cumxx". + + Device naming when more than 2 boards installed + ----------------------------------------------- + Naming convention for each Smartio/Industio multiport board is + pre-defined as below. + + Board Num. Dial-in Port Callout port + 1st board ttyM0 - ttyM7 cum0 - cum7 + 2nd board ttyM8 - ttyM15 cum8 - cum15 + 3rd board ttyM16 - ttyM23 cum16 - cum23 + 4th board ttyM24 - ttym31 cum24 - cum31 + + + !!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + Under Kernel 2.6 the cum Device is Obsolete. So use ttyM* + device instead. + !!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + + Board sequence + -------------- + This driver will activate ISA boards according to the parameter set + in the driver. After all specified ISA board activated, PCI board + will be installed in the system automatically driven. + Therefore the board number is sorted by the CAP address of ISA boards. + For PCI boards, their sequence will be after ISA boards and C168H/PCI + has higher priority than C104H/PCI boards. + + 3.4 Module driver configuration + Module driver is easiest way to install. If you prefer static driver + installation, please skip this paragraph. + + + ------------- Prepare to use the MOXA driver-------------------- + 3.4.1 Create tty device with correct major number + Before using MOXA driver, your system must have the tty devices + which are created with driver's major number. We offer one shell + script "msmknod" to simplify the procedure. + This step is only needed to be executed once. But you still + need to do this procedure when: + a. You change the driver's major number. Please refer the "3.7" + section. + b. Your total installed MOXA boards number is changed. Maybe you + add/delete one MOXA board. + c. You want to change the tty name. This needs to modify the + shell script "msmknod" + + The procedure is: + # cd /moxa/mxser/driver + # ./msmknod + + This shell script will require the major number for dial-in + device and callout device to create tty device. You also need + to specify the total installed MOXA board number. Default major + numbers for dial-in device and callout device are 30, 35. If + you need to change to other number, please refer section "3.7" + for more detailed procedure. + Msmknod will delete any special files occupying the same device + naming. + + 3.4.2 Build the MOXA driver and utilities + Before using the MOXA driver and utilities, you need compile the + all the source code. This step is only need to be executed once. + But you still re-compile the source code if you modify the source + code. For example, if you change the driver's major number (see + "3.7" section), then you need to do this step again. + + Find "Makefile" in /moxa/mxser, then run + + # make clean; make install + + !!!!!!!!!! NOTE !!!!!!!!!!!!!!!!! + For Red Hat 9, Red Hat Enterprise Linux AS3/ES3/WS3 & Fedora Core1: + # make clean; make installsp1 + + For Red Hat Enterprise Linux AS4/ES4/WS4: + # make clean; make installsp2 + !!!!!!!!!! NOTE !!!!!!!!!!!!!!!!! + + The driver files "mxser.o" and utilities will be properly compiled + and copied to system directories respectively. + + ------------- Load MOXA driver-------------------- + 3.4.3 Load the MOXA driver + + # modprobe mxser <argument> + + will activate the module driver. You may run "lsmod" to check + if "mxser" is activated. If the MOXA board is ISA board, the + <argument> is needed. Please refer to section "3.4.5" for more + information. + + + ------------- Load MOXA driver on boot -------------------- + 3.4.4 For the above description, you may manually execute + "modprobe mxser" to activate this driver and run + "rmmod mxser" to remove it. + However, it's better to have a boot time configuration to + eliminate manual operation. Boot time configuration can be + achieved by rc file. We offer one "rc.mxser" file to simplify + the procedure under "moxa/mxser/driver". + + But if you use ISA board, please modify the "modprobe ..." command + to add the argument (see "3.4.5" section). After modifying the + rc.mxser, please try to execute "/moxa/mxser/driver/rc.mxser" + manually to make sure the modification is ok. If any error + encountered, please try to modify again. If the modification is + completed, follow the below step. + + Run following command for setting rc files. + + # cd /moxa/mxser/driver + # cp ./rc.mxser /etc/rc.d + # cd /etc/rc.d + + Check "rc.serial" is existed or not. If "rc.serial" doesn't exist, + create it by vi, run "chmod 755 rc.serial" to change the permission. + Add "/etc/rc.d/rc.mxser" in last line, + + Reboot and check if moxa.o activated by "lsmod" command. + + 3.4.5. If you'd like to drive Smartio/Industio ISA boards in the system, + you'll have to add parameter to specify CAP address of given + board while activating "mxser.o". The format for parameters are + as follows. + + modprobe mxser ioaddr=0x???,0x???,0x???,0x??? + | | | | + | | | +- 4th ISA board + | | +------ 3rd ISA board + | +------------ 2nd ISA board + +------------------- 1st ISA board + + 3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x + + Note: To use static driver, you must install the linux kernel + source package. + + 3.5.1 Backup the built-in driver in the kernel. + # cd /usr/src/linux/drivers/char + # mv mxser.c mxser.c.old + + For Red Hat 7.x user, you need to create link: + # cd /usr/src + # ln -s linux-2.4 linux + + 3.5.2 Create link + # cd /usr/src/linux/drivers/char + # ln -s /moxa/mxser/driver/mxser.c mxser.c + + 3.5.3 Add CAP address list for ISA boards. For PCI boards user, + please skip this step. + + In module mode, the CAP address for ISA board is given by + parameter. In static driver configuration, you'll have to + assign it within driver's source code. If you will not + install any ISA boards, you may skip to next portion. + The instructions to modify driver source code are as + below. + a. # cd /moxa/mxser/driver + # vi mxser.c + b. Find the array mxserBoardCAP[] as below. + + static int mxserBoardCAP[] + = {0x00, 0x00, 0x00, 0x00}; + + c. Change the address within this array using vi. For + example, to driver 2 ISA boards with CAP address + 0x280 and 0x180 as 1st and 2nd board. Just to change + the source code as follows. + + static int mxserBoardCAP[] + = {0x280, 0x180, 0x00, 0x00}; + + 3.5.4 Setup kernel configuration + + Configure the kernel: + + # cd /usr/src/linux + # make menuconfig + + You will go into a menu-driven system. Please select [Character + devices][Non-standard serial port support], enable the [Moxa + SmartIO support] driver with "[*]" for built-in (not "[M]"), then + select [Exit] to exit this program. + + 3.5.5 Rebuild kernel + The following are for Linux kernel rebuilding, for your + reference only. + For appropriate details, please refer to the Linux document. + + a. cd /usr/src/linux + b. make clean /* take a few minutes */ + c. make dep /* take a few minutes */ + d. make bzImage /* take probably 10-20 minutes */ + e. make install /* copy boot image to correct position */ + f. Please make sure the boot kernel (vmlinuz) is in the + correct position. + g. If you use 'lilo' utility, you should check /etc/lilo.conf + 'image' item specified the path which is the 'vmlinuz' path, + or you will load wrong (or old) boot kernel image (vmlinuz). + After checking /etc/lilo.conf, please run "lilo". + + Note that if the result of "make bzImage" is ERROR, then you have to + go back to Linux configuration Setup. Type "make menuconfig" in + directory /usr/src/linux. + + + 3.5.6 Make tty device and special file + # cd /moxa/mxser/driver + # ./msmknod + + 3.5.7 Make utility + # cd /moxa/mxser/utility + # make clean; make install + + 3.5.8 Reboot + + + + 3.6 Custom configuration + Although this driver already provides you default configuration, you + still can change the device name and major number. The instruction to + change these parameters are shown as below. + + Change Device name + ------------------ + If you'd like to use other device names instead of default naming + convention, all you have to do is to modify the internal code + within the shell script "msmknod". First, you have to open "msmknod" + by vi. Locate each line contains "ttyM" and "cum" and change them + to the device name you desired. "msmknod" creates the device names + you need next time executed. + + Change Major number + ------------------- + If major number 30 and 35 had been occupied, you may have to select + 2 free major numbers for this driver. There are 3 steps to change + major numbers. + + 3.6.1 Find free major numbers + In /proc/devices, you may find all the major numbers occupied + in the system. Please select 2 major numbers that are available. + e.g. 40, 45. + 3.6.2 Create special files + Run /moxa/mxser/driver/msmknod to create special files with + specified major numbers. + 3.6.3 Modify driver with new major number + Run vi to open /moxa/mxser/driver/mxser.c. Locate the line + contains "MXSERMAJOR". Change the content as below. + #define MXSERMAJOR 40 + #define MXSERCUMAJOR 45 + 3.6.4 Run "make clean; make install" in /moxa/mxser/driver. + + 3.7 Verify driver installation + You may refer to /var/log/messages to check the latest status + log reported by this driver whenever it's activated. + +----------------------------------------------------------------------------- +4. Utilities + There are 3 utilities contained in this driver. They are msdiag, msmon and + msterm. These 3 utilities are released in form of source code. They should + be compiled into executable file and copied into /usr/bin. + + Before using these utilities, please load driver (refer 3.4 & 3.5) and + make sure you had run the "msmknod" utility. + + msdiag - Diagnostic + -------------------- + This utility provides the function to display what Moxa Smartio/Industio + board found by driver in the system. + + msmon - Port Monitoring + ----------------------- + This utility gives the user a quick view about all the MOXA ports' + activities. One can easily learn each port's total received/transmitted + (Rx/Tx) character count since the time when the monitoring is started. + Rx/Tx throughputs per second are also reported in interval basis (e.g. + the last 5 seconds) and in average basis (since the time the monitoring + is started). You can reset all ports' count by <HOME> key. <+> <-> + (plus/minus) keys to change the displaying time interval. Press <ENTER> + on the port, that cursor stay, to view the port's communication + parameters, signal status, and input/output queue. + + msterm - Terminal Emulation + --------------------------- + This utility provides data sending and receiving ability of all tty ports, + especially for MOXA ports. It is quite useful for testing simple + application, for example, sending AT command to a modem connected to the + port or used as a terminal for login purpose. Note that this is only a + dumb terminal emulation without handling full screen operation. + +----------------------------------------------------------------------------- +5. Setserial + + Supported Setserial parameters are listed as below. + + uart set UART type(16450-->disable FIFO, 16550A-->enable FIFO) + close_delay set the amount of time(in 1/100 of a second) that DTR + should be kept low while being closed. + closing_wait set the amount of time(in 1/100 of a second) that the + serial port should wait for data to be drained while + being closed, before the receiver is disable. + spd_hi Use 57.6kb when the application requests 38.4kb. + spd_vhi Use 115.2kb when the application requests 38.4kb. + spd_shi Use 230.4kb when the application requests 38.4kb. + spd_warp Use 460.8kb when the application requests 38.4kb. + spd_normal Use 38.4kb when the application requests 38.4kb. + spd_cust Use the custom divisor to set the speed when the + application requests 38.4kb. + divisor This option set the custom division. + baud_base This option set the base baud rate. + +----------------------------------------------------------------------------- +6. Troubleshooting + + The boot time error messages and solutions are stated as clearly as + possible. If all the possible solutions fail, please contact our technical + support team to get more help. + + + Error msg: More than 4 Moxa Smartio/Industio family boards found. Fifth board + and after are ignored. + Solution: + To avoid this problem, please unplug fifth and after board, because Moxa + driver supports up to 4 boards. + + Error msg: Request_irq fail, IRQ(?) may be conflict with another device. + Solution: + Other PCI or ISA devices occupy the assigned IRQ. If you are not sure + which device causes the situation, please check /proc/interrupts to find + free IRQ and simply change another free IRQ for Moxa board. + + Error msg: Board #: C1xx Series(CAP=xxx) interrupt number invalid. + Solution: + Each port within the same multiport board shares the same IRQ. Please set + one IRQ (IRQ doesn't equal to zero) for one Moxa board. + + Error msg: No interrupt vector be set for Moxa ISA board(CAP=xxx). + Solution: + Moxa ISA board needs an interrupt vector.Please refer to user's manual + "Hardware Installation" chapter to set interrupt vector. + + Error msg: Couldn't install MOXA Smartio/Industio family driver! + Solution: + Load Moxa driver fail, the major number may conflict with other devices. + Please refer to previous section 3.7 to change a free major number for + Moxa driver. + + Error msg: Couldn't install MOXA Smartio/Industio family callout driver! + Solution: + Load Moxa callout driver fail, the callout device major number may + conflict with other devices. Please refer to previous section 3.7 to + change a free callout device major number for Moxa driver. + + +----------------------------------------------------------------------------- + diff --git a/Documentation/serial/n_gsm.txt b/Documentation/serial/n_gsm.txt new file mode 100644 index 000000000..875361bb7 --- /dev/null +++ b/Documentation/serial/n_gsm.txt @@ -0,0 +1,96 @@ +n_gsm.c GSM 0710 tty multiplexor HOWTO +=================================================== + +This line discipline implements the GSM 07.10 multiplexing protocol +detailed in the following 3GPP document : +http://www.3gpp.org/ftp/Specs/archive/07_series/07.10/0710-720.zip + +This document give some hints on how to use this driver with GPRS and 3G +modems connected to a physical serial port. + +How to use it +------------- +1- initialize the modem in 0710 mux mode (usually AT+CMUX= command) through +its serial port. Depending on the modem used, you can pass more or less +parameters to this command, +2- switch the serial line to using the n_gsm line discipline by using +TIOCSETD ioctl, +3- configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl, + +Major parts of the initialization program : +(a good starting point is util-linux-ng/sys-utils/ldattach.c) +#include <linux/gsmmux.h> +#define N_GSM0710 21 /* GSM 0710 Mux */ +#define DEFAULT_SPEED B115200 +#define SERIAL_PORT /dev/ttyS0 + + int ldisc = N_GSM0710; + struct gsm_config c; + struct termios configuration; + + /* open the serial port connected to the modem */ + fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY); + + /* configure the serial port : speed, flow control ... */ + + /* send the AT commands to switch the modem to CMUX mode + and check that it's successful (should return OK) */ + write(fd, "AT+CMUX=0\r", 10); + + /* experience showed that some modems need some time before + being able to answer to the first MUX packet so a delay + may be needed here in some case */ + sleep(3); + + /* use n_gsm line discipline */ + ioctl(fd, TIOCSETD, &ldisc); + + /* get n_gsm configuration */ + ioctl(fd, GSMIOC_GETCONF, &c); + /* we are initiator and need encoding 0 (basic) */ + c.initiator = 1; + c.encapsulation = 0; + /* our modem defaults to a maximum size of 127 bytes */ + c.mru = 127; + c.mtu = 127; + /* set the new configuration */ + ioctl(fd, GSMIOC_SETCONF, &c); + + /* and wait for ever to keep the line discipline enabled */ + daemon(0,0); + pause(); + +4- create the devices corresponding to the "virtual" serial ports (take care, +each modem has its configuration and some DLC have dedicated functions, +for example GPS), starting with minor 1 (DLC0 is reserved for the management +of the mux) + +MAJOR=`cat /proc/devices |grep gsmtty | awk '{print $1}` +for i in `seq 1 4`; do + mknod /dev/ttygsm$i c $MAJOR $i +done + +5- use these devices as plain serial ports. +for example, it's possible : +- and to use gnokii to send / receive SMS on ttygsm1 +- to use ppp to establish a datalink on ttygsm2 + +6- first close all virtual ports before closing the physical port. + +Note that after closing the physical port the modem is still in multiplexing +mode. This may prevent a successful re-opening of the port later. To avoid +this situation either reset the modem if your hardware allows that or send +a disconnect command frame manually before initializing the multiplexing mode +for the second time. The byte sequence for the disconnect command frame is: +0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9. + +Additional Documentation +------------------------ +More practical details on the protocol and how it's supported by industrial +modems can be found in the following documents : +http://www.telit.com/module/infopool/download.php?id=616 +http://www.u-blox.com/images/downloads/Product_Docs/LEON-G100-G200-MuxImplementation_ApplicationNote_%28GSM%20G1-CS-10002%29.pdf +http://www.sierrawireless.com/Support/Downloads/AirPrime/WMP_Series/~/media/Support_Downloads/AirPrime/Application_notes/CMUX_Feature_Application_Note-Rev004.ashx +http://wm.sim.com/sim/News/photo/2010721161442.pdf + +11-03-08 - Eric Bénard - <eric@eukrea.com> diff --git a/Documentation/serial/rocket.txt b/Documentation/serial/rocket.txt new file mode 100644 index 000000000..60b039891 --- /dev/null +++ b/Documentation/serial/rocket.txt @@ -0,0 +1,189 @@ +Comtrol(tm) RocketPort(R)/RocketModem(TM) Series +Device Driver for the Linux Operating System + +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- + +PRODUCT OVERVIEW +---------------- + +This driver provides a loadable kernel driver for the Comtrol RocketPort +and RocketModem PCI boards. These boards provide, 2, 4, 8, 16, or 32 +high-speed serial ports or modems. This driver supports up to a combination +of four RocketPort or RocketModems boards in one machine simultaneously. +This file assumes that you are using the RocketPort driver which is +integrated into the kernel sources. + +The driver can also be installed as an external module using the usual +"make;make install" routine. This external module driver, obtainable +from the Comtrol website listed below, is useful for updating the driver +or installing it into kernels which do not have the driver configured +into them. Installations instructions for the external module +are in the included README and HW_INSTALL files. + +RocketPort ISA and RocketModem II PCI boards currently are only supported by +this driver in module form. + +The RocketPort ISA board requires I/O ports to be configured by the DIP +switches on the board. See the section "ISA Rocketport Boards" below for +information on how to set the DIP switches. + +You pass the I/O port to the driver using the following module parameters: + +board1 : I/O port for the first ISA board +board2 : I/O port for the second ISA board +board3 : I/O port for the third ISA board +board4 : I/O port for the fourth ISA board + +There is a set of utilities and scripts provided with the external driver +( downloadable from http://www.comtrol.com ) that ease the configuration and +setup of the ISA cards. + +The RocketModem II PCI boards require firmware to be loaded into the card +before it will function. The driver has only been tested as a module for this +board. + +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- + +INSTALLATION PROCEDURES +----------------------- + +RocketPort/RocketModem PCI cards require no driver configuration, they are +automatically detected and configured. + +The RocketPort driver can be installed as a module (recommended) or built +into the kernel. This is selected, as for other drivers, through the `make config` +command from the root of the Linux source tree during the kernel build process. + +The RocketPort/RocketModem serial ports installed by this driver are assigned +device major number 46, and will be named /dev/ttyRx, where x is the port number +starting at zero (ex. /dev/ttyR0, /devttyR1, ...). If you have multiple cards +installed in the system, the mapping of port names to serial ports is displayed +in the system log at /var/log/messages. + +If installed as a module, the module must be loaded. This can be done +manually by entering "modprobe rocket". To have the module loaded automatically +upon system boot, edit a /etc/modprobe.d/*.conf file and add the line +"alias char-major-46 rocket". + +In order to use the ports, their device names (nodes) must be created with mknod. +This is only required once, the system will retain the names once created. To +create the RocketPort/RocketModem device names, use the command +"mknod /dev/ttyRx c 46 x" where x is the port number starting at zero. For example: + +>mknod /dev/ttyR0 c 46 0 +>mknod /dev/ttyR1 c 46 1 +>mknod /dev/ttyR2 c 46 2 + +The Linux script MAKEDEV will create the first 16 ttyRx device names (nodes) +for you: + +>/dev/MAKEDEV ttyR + +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- + +ISA Rocketport Boards +--------------------- + +You must assign and configure the I/O addresses used by the ISA Rocketport +card before installing and using it. This is done by setting a set of DIP +switches on the Rocketport board. + + +SETTING THE I/O ADDRESS +----------------------- + +Before installing RocketPort(R) or RocketPort RA boards, you must find +a range of I/O addresses for it to use. The first RocketPort card +requires a 68-byte contiguous block of I/O addresses, starting at one +of the following: 0x100h, 0x140h, 0x180h, 0x200h, 0x240h, 0x280h, +0x300h, 0x340h, 0x380h. This I/O address must be reflected in the DIP +switches of *all* of the Rocketport cards. + +The second, third, and fourth RocketPort cards require a 64-byte +contiguous block of I/O addresses, starting at one of the following +I/O addresses: 0x100h, 0x140h, 0x180h, 0x1C0h, 0x200h, 0x240h, 0x280h, +0x2C0h, 0x300h, 0x340h, 0x380h, 0x3C0h. The I/O address used by the +second, third, and fourth Rocketport cards (if present) are set via +software control. The DIP switch settings for the I/O address must be +set to the value of the first Rocketport cards. + +In order to distinguish each of the card from the others, each card +must have a unique board ID set on the dip switches. The first +Rocketport board must be set with the DIP switches corresponding to +the first board, the second board must be set with the DIP switches +corresponding to the second board, etc. IMPORTANT: The board ID is +the only place where the DIP switch settings should differ between the +various Rocketport boards in a system. + +The I/O address range used by any of the RocketPort cards must not +conflict with any other cards in the system, including other +RocketPort cards. Below, you will find a list of commonly used I/O +address ranges which may be in use by other devices in your system. +On a Linux system, "cat /proc/ioports" will also be helpful in +identifying what I/O addresses are being used by devices on your +system. + +Remember, the FIRST RocketPort uses 68 I/O addresses. So, if you set it +for 0x100, it will occupy 0x100 to 0x143. This would mean that you +CAN NOT set the second, third or fourth board for address 0x140 since +the first 4 bytes of that range are used by the first board. You would +need to set the second, third, or fourth board to one of the next available +blocks such as 0x180. + +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- + +RocketPort and RocketPort RA SW1 Settings: + + +-------------------------------+ + | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | + +-------+-------+---------------+ + | Unused| Card | I/O Port Block| + +-------------------------------+ + +DIP Switches DIP Switches +7 8 6 5 +=================== =================== +On On UNUSED, MUST BE ON. On On First Card <==== Default + On Off Second Card + Off On Third Card + Off Off Fourth Card + +DIP Switches I/O Address Range +4 3 2 1 Used by the First Card +===================================== +On Off On Off 100-143 +On Off Off On 140-183 +On Off Off Off 180-1C3 <==== Default +Off On On Off 200-243 +Off On Off On 240-283 +Off On Off Off 280-2C3 +Off Off On Off 300-343 +Off Off Off On 340-383 +Off Off Off Off 380-3C3 + +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- + +REPORTING BUGS +-------------- + +For technical support, please provide the following +information: Driver version, kernel release, distribution of +kernel, and type of board you are using. Error messages and log +printouts port configuration details are especially helpful. + +USA + Phone: (612) 494-4100 + FAX: (612) 494-4199 + email: support@comtrol.com + +Comtrol Europe + Phone: +44 (0) 1 869 323-220 + FAX: +44 (0) 1 869 323-211 + email: support@comtrol.co.uk + +Web: http://www.comtrol.com +FTP: ftp.comtrol.com + +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- + + diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt new file mode 100644 index 000000000..389fcd475 --- /dev/null +++ b/Documentation/serial/serial-rs485.txt @@ -0,0 +1,95 @@ + RS485 SERIAL COMMUNICATIONS + +1. INTRODUCTION + + EIA-485, also known as TIA/EIA-485 or RS-485, is a standard defining the + electrical characteristics of drivers and receivers for use in balanced + digital multipoint systems. + This standard is widely used for communications in industrial automation + because it can be used effectively over long distances and in electrically + noisy environments. + +2. HARDWARE-RELATED CONSIDERATIONS + + Some CPUs/UARTs (e.g., Atmel AT91 or 16C950 UART) contain a built-in + half-duplex mode capable of automatically controlling line direction by + toggling RTS or DTR signals. That can be used to control external + half-duplex hardware like an RS485 transceiver or any RS232-connected + half-duplex devices like some modems. + + For these microcontrollers, the Linux driver should be made capable of + working in both modes, and proper ioctls (see later) should be made + available at user-level to allow switching from one mode to the other, and + vice versa. + +3. DATA STRUCTURES ALREADY AVAILABLE IN THE KERNEL + + The Linux kernel provides the serial_rs485 structure (see [1]) to handle + RS485 communications. This data structure is used to set and configure RS485 + parameters in the platform data and in ioctls. + + The device tree can also provide RS485 boot time parameters (see [2] + for bindings). The driver is in charge of filling this data structure from + the values given by the device tree. + + Any driver for devices capable of working both as RS232 and RS485 should + implement the rs485_config callback in the uart_port structure. The + serial_core calls rs485_config to do the device specific part in response + to TIOCSRS485 and TIOCGRS485 ioctls (see below). The rs485_config callback + receives a pointer to struct serial_rs485. + +4. USAGE FROM USER-LEVEL + + From user-level, RS485 configuration can be get/set using the previous + ioctls. For instance, to set RS485 you can use the following code: + + #include <linux/serial.h> + + /* Include definition for RS485 ioctls: TIOCGRS485 and TIOCSRS485 */ + #include <sys/ioctl.h> + + /* Open your specific device (e.g., /dev/mydevice): */ + int fd = open ("/dev/mydevice", O_RDWR); + if (fd < 0) { + /* Error handling. See errno. */ + } + + struct serial_rs485 rs485conf; + + /* Enable RS485 mode: */ + rs485conf.flags |= SER_RS485_ENABLED; + + /* Set logical level for RTS pin equal to 1 when sending: */ + rs485conf.flags |= SER_RS485_RTS_ON_SEND; + /* or, set logical level for RTS pin equal to 0 when sending: */ + rs485conf.flags &= ~(SER_RS485_RTS_ON_SEND); + + /* Set logical level for RTS pin equal to 1 after sending: */ + rs485conf.flags |= SER_RS485_RTS_AFTER_SEND; + /* or, set logical level for RTS pin equal to 0 after sending: */ + rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND); + + /* Set rts delay before send, if needed: */ + rs485conf.delay_rts_before_send = ...; + + /* Set rts delay after send, if needed: */ + rs485conf.delay_rts_after_send = ...; + + /* Set this flag if you want to receive data even whilst sending data */ + rs485conf.flags |= SER_RS485_RX_DURING_TX; + + if (ioctl (fd, TIOCSRS485, &rs485conf) < 0) { + /* Error handling. See errno. */ + } + + /* Use read() and write() syscalls here... */ + + /* Close the device when finished: */ + if (close (fd) < 0) { + /* Error handling. See errno. */ + } + +5. REFERENCES + + [1] include/uapi/linux/serial.h + [2] Documentation/devicetree/bindings/serial/rs485.txt diff --git a/Documentation/serial/tty.txt b/Documentation/serial/tty.txt new file mode 100644 index 000000000..b48780977 --- /dev/null +++ b/Documentation/serial/tty.txt @@ -0,0 +1,313 @@ + + The Lockronomicon + +Your guide to the ancient and twisted locking policies of the tty layer and +the warped logic behind them. Beware all ye who read on. + + +Line Discipline +--------------- + +Line disciplines are registered with tty_register_ldisc() passing the +discipline number and the ldisc structure. At the point of registration the +discipline must be ready to use and it is possible it will get used before +the call returns success. If the call returns an error then it won't get +called. Do not re-use ldisc numbers as they are part of the userspace ABI +and writing over an existing ldisc will cause demons to eat your computer. +After the return the ldisc data has been copied so you may free your own +copy of the structure. You must not re-register over the top of the line +discipline even with the same data or your computer again will be eaten by +demons. + +In order to remove a line discipline call tty_unregister_ldisc(). +In ancient times this always worked. In modern times the function will +return -EBUSY if the ldisc is currently in use. Since the ldisc referencing +code manages the module counts this should not usually be a concern. + +Heed this warning: the reference count field of the registered copies of the +tty_ldisc structure in the ldisc table counts the number of lines using this +discipline. The reference count of the tty_ldisc structure within a tty +counts the number of active users of the ldisc at this instant. In effect it +counts the number of threads of execution within an ldisc method (plus those +about to enter and exit although this detail matters not). + +Line Discipline Methods +----------------------- + +TTY side interfaces: + +open() - Called when the line discipline is attached to + the terminal. No other call into the line + discipline for this tty will occur until it + completes successfully. Should initialize any + state needed by the ldisc, and set receive_room + in the tty_struct to the maximum amount of data + the line discipline is willing to accept from the + driver with a single call to receive_buf(). + Returning an error will prevent the ldisc from + being attached. Can sleep. + +close() - This is called on a terminal when the line + discipline is being unplugged. At the point of + execution no further users will enter the + ldisc code for this tty. Can sleep. + +hangup() - Called when the tty line is hung up. + The line discipline should cease I/O to the tty. + No further calls into the ldisc code will occur. + The return value is ignored. Can sleep. + +read() - (optional) A process requests reading data from + the line. Multiple read calls may occur in parallel + and the ldisc must deal with serialization issues. + If not defined, the process will receive an EIO + error. May sleep. + +write() - (optional) A process requests writing data to the + line. Multiple write calls are serialized by the + tty layer for the ldisc. If not defined, the + process will receive an EIO error. May sleep. + +flush_buffer() - (optional) May be called at any point between + open and close, and instructs the line discipline + to empty its input buffer. + +set_termios() - (optional) Called on termios structure changes. + The caller passes the old termios data and the + current data is in the tty. Called under the + termios semaphore so allowed to sleep. Serialized + against itself only. + +poll() - (optional) Check the status for the poll/select + calls. Multiple poll calls may occur in parallel. + May sleep. + +ioctl() - (optional) Called when an ioctl is handed to the + tty layer that might be for the ldisc. Multiple + ioctl calls may occur in parallel. May sleep. + +compat_ioctl() - (optional) Called when a 32 bit ioctl is handed + to the tty layer that might be for the ldisc. + Multiple ioctl calls may occur in parallel. + May sleep. + +Driver Side Interfaces: + +receive_buf() - (optional) Called by the low-level driver to hand + a buffer of received bytes to the ldisc for + processing. The number of bytes is guaranteed not + to exceed the current value of tty->receive_room. + All bytes must be processed. + +receive_buf2() - (optional) Called by the low-level driver to hand + a buffer of received bytes to the ldisc for + processing. Returns the number of bytes processed. + + If both receive_buf() and receive_buf2() are + defined, receive_buf2() should be preferred. + +write_wakeup() - May be called at any point between open and close. + The TTY_DO_WRITE_WAKEUP flag indicates if a call + is needed but always races versus calls. Thus the + ldisc must be careful about setting order and to + handle unexpected calls. Must not sleep. + + The driver is forbidden from calling this directly + from the ->write call from the ldisc as the ldisc + is permitted to call the driver write method from + this function. In such a situation defer it. + +dcd_change() - Report to the tty line the current DCD pin status + changes and the relative timestamp. The timestamp + cannot be NULL. + + +Driver Access + +Line discipline methods can call the following methods of the underlying +hardware driver through the function pointers within the tty->driver +structure: + +write() Write a block of characters to the tty device. + Returns the number of characters accepted. The + character buffer passed to this method is already + in kernel space. + +put_char() Queues a character for writing to the tty device. + If there is no room in the queue, the character is + ignored. + +flush_chars() (Optional) If defined, must be called after + queueing characters with put_char() in order to + start transmission. + +write_room() Returns the numbers of characters the tty driver + will accept for queueing to be written. + +ioctl() Invoke device specific ioctl. + Expects data pointers to refer to userspace. + Returns ENOIOCTLCMD for unrecognized ioctl numbers. + +set_termios() Notify the tty driver that the device's termios + settings have changed. New settings are in + tty->termios. Previous settings should be passed in + the "old" argument. + + The API is defined such that the driver should return + the actual modes selected. This means that the + driver function is responsible for modifying any + bits in the request it cannot fulfill to indicate + the actual modes being used. A device with no + hardware capability for change (e.g. a USB dongle or + virtual port) can provide NULL for this method. + +throttle() Notify the tty driver that input buffers for the + line discipline are close to full, and it should + somehow signal that no more characters should be + sent to the tty. + +unthrottle() Notify the tty driver that characters can now be + sent to the tty without fear of overrunning the + input buffers of the line disciplines. + +stop() Ask the tty driver to stop outputting characters + to the tty device. + +start() Ask the tty driver to resume sending characters + to the tty device. + +hangup() Ask the tty driver to hang up the tty device. + +break_ctl() (Optional) Ask the tty driver to turn on or off + BREAK status on the RS-232 port. If state is -1, + then the BREAK status should be turned on; if + state is 0, then BREAK should be turned off. + If this routine is not implemented, use ioctls + TIOCSBRK / TIOCCBRK instead. + +wait_until_sent() Waits until the device has written out all of the + characters in its transmitter FIFO. + +send_xchar() Send a high-priority XON/XOFF character to the device. + + +Flags + +Line discipline methods have access to tty->flags field containing the +following interesting flags: + +TTY_THROTTLED Driver input is throttled. The ldisc should call + tty->driver->unthrottle() in order to resume + reception when it is ready to process more data. + +TTY_DO_WRITE_WAKEUP If set, causes the driver to call the ldisc's + write_wakeup() method in order to resume + transmission when it can accept more data + to transmit. + +TTY_IO_ERROR If set, causes all subsequent userspace read/write + calls on the tty to fail, returning -EIO. + +TTY_OTHER_CLOSED Device is a pty and the other side has closed. + +TTY_NO_WRITE_SPLIT Prevent driver from splitting up writes into + smaller chunks. + + +Locking + +Callers to the line discipline functions from the tty layer are required to +take line discipline locks. The same is true of calls from the driver side +but not yet enforced. + +Three calls are now provided + + ldisc = tty_ldisc_ref(tty); + +takes a handle to the line discipline in the tty and returns it. If no ldisc +is currently attached or the ldisc is being closed and re-opened at this +point then NULL is returned. While this handle is held the ldisc will not +change or go away. + + tty_ldisc_deref(ldisc) + +Returns the ldisc reference and allows the ldisc to be closed. Returning the +reference takes away your right to call the ldisc functions until you take +a new reference. + + ldisc = tty_ldisc_ref_wait(tty); + +Performs the same function as tty_ldisc_ref except that it will wait for an +ldisc change to complete and then return a reference to the new ldisc. + +While these functions are slightly slower than the old code they should have +minimal impact as most receive logic uses the flip buffers and they only +need to take a reference when they push bits up through the driver. + +A caution: The ldisc->open(), ldisc->close() and driver->set_ldisc +functions are called with the ldisc unavailable. Thus tty_ldisc_ref will +fail in this situation if used within these functions. Ldisc and driver +code calling its own functions must be careful in this case. + + +Driver Interface +---------------- + +open() - Called when a device is opened. May sleep + +close() - Called when a device is closed. At the point of + return from this call the driver must make no + further ldisc calls of any kind. May sleep + +write() - Called to write bytes to the device. May not + sleep. May occur in parallel in special cases. + Because this includes panic paths drivers generally + shouldn't try and do clever locking here. + +put_char() - Stuff a single character onto the queue. The + driver is guaranteed following up calls to + flush_chars. + +flush_chars() - Ask the kernel to write put_char queue + +write_room() - Return the number of characters that can be stuffed + into the port buffers without overflow (or less). + The ldisc is responsible for being intelligent + about multi-threading of write_room/write calls + +ioctl() - Called when an ioctl may be for the driver + +set_termios() - Called on termios change, serialized against + itself by a semaphore. May sleep. + +set_ldisc() - Notifier for discipline change. At the point this + is done the discipline is not yet usable. Can now + sleep (I think) + +throttle() - Called by the ldisc to ask the driver to do flow + control. Serialization including with unthrottle + is the job of the ldisc layer. + +unthrottle() - Called by the ldisc to ask the driver to stop flow + control. + +stop() - Ldisc notifier to the driver to stop output. As with + throttle the serializations with start() are down + to the ldisc layer. + +start() - Ldisc notifier to the driver to start output. + +hangup() - Ask the tty driver to cause a hangup initiated + from the host side. [Can sleep ??] + +break_ctl() - Send RS232 break. Can sleep. Can get called in + parallel, driver must serialize (for now), and + with write calls. + +wait_until_sent() - Wait for characters to exit the hardware queue + of the driver. Can sleep + +send_xchar() - Send XON/XOFF and if possible jump the queue with + it in order to get fast flow control responses. + Cannot sleep ?? + |