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diff --git a/kernel/Documentation/parport-lowlevel.txt b/kernel/Documentation/parport-lowlevel.txt new file mode 100644 index 000000000..120eb20db --- /dev/null +++ b/kernel/Documentation/parport-lowlevel.txt @@ -0,0 +1,1471 @@ +PARPORT interface documentation +------------------------------- + +Time-stamp: <2000-02-24 13:30:20 twaugh> + +Described here are the following functions: + +Global functions: + parport_register_driver + parport_unregister_driver + parport_enumerate + parport_register_device + parport_unregister_device + parport_claim + parport_claim_or_block + parport_release + parport_yield + parport_yield_blocking + parport_wait_peripheral + parport_poll_peripheral + parport_wait_event + parport_negotiate + parport_read + parport_write + parport_open + parport_close + parport_device_id + parport_device_coords + parport_find_class + parport_find_device + parport_set_timeout + +Port functions (can be overridden by low-level drivers): + SPP: + port->ops->read_data + port->ops->write_data + port->ops->read_status + port->ops->read_control + port->ops->write_control + port->ops->frob_control + port->ops->enable_irq + port->ops->disable_irq + port->ops->data_forward + port->ops->data_reverse + + EPP: + port->ops->epp_write_data + port->ops->epp_read_data + port->ops->epp_write_addr + port->ops->epp_read_addr + + ECP: + port->ops->ecp_write_data + port->ops->ecp_read_data + port->ops->ecp_write_addr + + Other: + port->ops->nibble_read_data + port->ops->byte_read_data + port->ops->compat_write_data + +The parport subsystem comprises 'parport' (the core port-sharing +code), and a variety of low-level drivers that actually do the port +accesses. Each low-level driver handles a particular style of port +(PC, Amiga, and so on). + +The parport interface to the device driver author can be broken down +into global functions and port functions. + +The global functions are mostly for communicating between the device +driver and the parport subsystem: acquiring a list of available ports, +claiming a port for exclusive use, and so on. They also include +'generic' functions for doing standard things that will work on any +IEEE 1284-capable architecture. + +The port functions are provided by the low-level drivers, although the +core parport module provides generic 'defaults' for some routines. +The port functions can be split into three groups: SPP, EPP, and ECP. + +SPP (Standard Parallel Port) functions modify so-called 'SPP' +registers: data, status, and control. The hardware may not actually +have registers exactly like that, but the PC does and this interface is +modelled after common PC implementations. Other low-level drivers may +be able to emulate most of the functionality. + +EPP (Enhanced Parallel Port) functions are provided for reading and +writing in IEEE 1284 EPP mode, and ECP (Extended Capabilities Port) +functions are used for IEEE 1284 ECP mode. (What about BECP? Does +anyone care?) + +Hardware assistance for EPP and/or ECP transfers may or may not be +available, and if it is available it may or may not be used. If +hardware is not used, the transfer will be software-driven. In order +to cope with peripherals that only tenuously support IEEE 1284, a +low-level driver specific function is provided, for altering 'fudge +factors'. + +GLOBAL FUNCTIONS +---------------- + +parport_register_driver - register a device driver with parport +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_driver { + const char *name; + void (*attach) (struct parport *); + void (*detach) (struct parport *); + struct parport_driver *next; +}; +int parport_register_driver (struct parport_driver *driver); + +DESCRIPTION + +In order to be notified about parallel ports when they are detected, +parport_register_driver should be called. Your driver will +immediately be notified of all ports that have already been detected, +and of each new port as low-level drivers are loaded. + +A 'struct parport_driver' contains the textual name of your driver, +a pointer to a function to handle new ports, and a pointer to a +function to handle ports going away due to a low-level driver +unloading. Ports will only be detached if they are not being used +(i.e. there are no devices registered on them). + +The visible parts of the 'struct parport *' argument given to +attach/detach are: + +struct parport +{ + struct parport *next; /* next parport in list */ + const char *name; /* port's name */ + unsigned int modes; /* bitfield of hardware modes */ + struct parport_device_info probe_info; + /* IEEE1284 info */ + int number; /* parport index */ + struct parport_operations *ops; + ... +}; + +There are other members of the structure, but they should not be +touched. + +The 'modes' member summarises the capabilities of the underlying +hardware. It consists of flags which may be bitwise-ored together: + + PARPORT_MODE_PCSPP IBM PC registers are available, + i.e. functions that act on data, + control and status registers are + probably writing directly to the + hardware. + PARPORT_MODE_TRISTATE The data drivers may be turned off. + This allows the data lines to be used + for reverse (peripheral to host) + transfers. + PARPORT_MODE_COMPAT The hardware can assist with + compatibility-mode (printer) + transfers, i.e. compat_write_block. + PARPORT_MODE_EPP The hardware can assist with EPP + transfers. + PARPORT_MODE_ECP The hardware can assist with ECP + transfers. + PARPORT_MODE_DMA The hardware can use DMA, so you might + want to pass ISA DMA-able memory + (i.e. memory allocated using the + GFP_DMA flag with kmalloc) to the + low-level driver in order to take + advantage of it. + +There may be other flags in 'modes' as well. + +The contents of 'modes' is advisory only. For example, if the +hardware is capable of DMA, and PARPORT_MODE_DMA is in 'modes', it +doesn't necessarily mean that DMA will always be used when possible. +Similarly, hardware that is capable of assisting ECP transfers won't +necessarily be used. + +RETURN VALUE + +Zero on success, otherwise an error code. + +ERRORS + +None. (Can it fail? Why return int?) + +EXAMPLE + +static void lp_attach (struct parport *port) +{ + ... + private = kmalloc (...); + dev[count++] = parport_register_device (...); + ... +} + +static void lp_detach (struct parport *port) +{ + ... +} + +static struct parport_driver lp_driver = { + "lp", + lp_attach, + lp_detach, + NULL /* always put NULL here */ +}; + +int lp_init (void) +{ + ... + if (parport_register_driver (&lp_driver)) { + /* Failed; nothing we can do. */ + return -EIO; + } + ... +} + +SEE ALSO + +parport_unregister_driver, parport_register_device, parport_enumerate + +parport_unregister_driver - tell parport to forget about this driver +------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_driver { + const char *name; + void (*attach) (struct parport *); + void (*detach) (struct parport *); + struct parport_driver *next; +}; +void parport_unregister_driver (struct parport_driver *driver); + +DESCRIPTION + +This tells parport not to notify the device driver of new ports or of +ports going away. Registered devices belonging to that driver are NOT +unregistered: parport_unregister_device must be used for each one. + +EXAMPLE + +void cleanup_module (void) +{ + ... + /* Stop notifications. */ + parport_unregister_driver (&lp_driver); + + /* Unregister devices. */ + for (i = 0; i < NUM_DEVS; i++) + parport_unregister_device (dev[i]); + ... +} + +SEE ALSO + +parport_register_driver, parport_enumerate + +parport_enumerate - retrieve a list of parallel ports (DEPRECATED) +----------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport *parport_enumerate (void); + +DESCRIPTION + +Retrieve the first of a list of valid parallel ports for this machine. +Successive parallel ports can be found using the 'struct parport +*next' element of the 'struct parport *' that is returned. If 'next' +is NULL, there are no more parallel ports in the list. The number of +ports in the list will not exceed PARPORT_MAX. + +RETURN VALUE + +A 'struct parport *' describing a valid parallel port for the machine, +or NULL if there are none. + +ERRORS + +This function can return NULL to indicate that there are no parallel +ports to use. + +EXAMPLE + +int detect_device (void) +{ + struct parport *port; + + for (port = parport_enumerate (); + port != NULL; + port = port->next) { + /* Try to detect a device on the port... */ + ... + } + } + + ... +} + +NOTES + +parport_enumerate is deprecated; parport_register_driver should be +used instead. + +SEE ALSO + +parport_register_driver, parport_unregister_driver + +parport_register_device - register to use a port +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +typedef int (*preempt_func) (void *handle); +typedef void (*wakeup_func) (void *handle); +typedef int (*irq_func) (int irq, void *handle, struct pt_regs *); + +struct pardevice *parport_register_device(struct parport *port, + const char *name, + preempt_func preempt, + wakeup_func wakeup, + irq_func irq, + int flags, + void *handle); + +DESCRIPTION + +Use this function to register your device driver on a parallel port +('port'). Once you have done that, you will be able to use +parport_claim and parport_release in order to use the port. + +The ('name') argument is the name of the device that appears in /proc +filesystem. The string must be valid for the whole lifetime of the +device (until parport_unregister_device is called). + +This function will register three callbacks into your driver: +'preempt', 'wakeup' and 'irq'. Each of these may be NULL in order to +indicate that you do not want a callback. + +When the 'preempt' function is called, it is because another driver +wishes to use the parallel port. The 'preempt' function should return +non-zero if the parallel port cannot be released yet -- if zero is +returned, the port is lost to another driver and the port must be +re-claimed before use. + +The 'wakeup' function is called once another driver has released the +port and no other driver has yet claimed it. You can claim the +parallel port from within the 'wakeup' function (in which case the +claim is guaranteed to succeed), or choose not to if you don't need it +now. + +If an interrupt occurs on the parallel port your driver has claimed, +the 'irq' function will be called. (Write something about shared +interrupts here.) + +The 'handle' is a pointer to driver-specific data, and is passed to +the callback functions. + +'flags' may be a bitwise combination of the following flags: + + Flag Meaning + PARPORT_DEV_EXCL The device cannot share the parallel port at all. + Use this only when absolutely necessary. + +The typedefs are not actually defined -- they are only shown in order +to make the function prototype more readable. + +The visible parts of the returned 'struct pardevice' are: + +struct pardevice { + struct parport *port; /* Associated port */ + void *private; /* Device driver's 'handle' */ + ... +}; + +RETURN VALUE + +A 'struct pardevice *': a handle to the registered parallel port +device that can be used for parport_claim, parport_release, etc. + +ERRORS + +A return value of NULL indicates that there was a problem registering +a device on that port. + +EXAMPLE + +static int preempt (void *handle) +{ + if (busy_right_now) + return 1; + + must_reclaim_port = 1; + return 0; +} + +static void wakeup (void *handle) +{ + struct toaster *private = handle; + struct pardevice *dev = private->dev; + if (!dev) return; /* avoid races */ + + if (want_port) + parport_claim (dev); +} + +static int toaster_detect (struct toaster *private, struct parport *port) +{ + private->dev = parport_register_device (port, "toaster", preempt, + wakeup, NULL, 0, + private); + if (!private->dev) + /* Couldn't register with parport. */ + return -EIO; + + must_reclaim_port = 0; + busy_right_now = 1; + parport_claim_or_block (private->dev); + ... + /* Don't need the port while the toaster warms up. */ + busy_right_now = 0; + ... + busy_right_now = 1; + if (must_reclaim_port) { + parport_claim_or_block (private->dev); + must_reclaim_port = 0; + } + ... +} + +SEE ALSO + +parport_unregister_device, parport_claim + +parport_unregister_device - finish using a port +------------------------- + +SYNPOPSIS + +#include <linux/parport.h> + +void parport_unregister_device (struct pardevice *dev); + +DESCRIPTION + +This function is the opposite of parport_register_device. After using +parport_unregister_device, 'dev' is no longer a valid device handle. + +You should not unregister a device that is currently claimed, although +if you do it will be released automatically. + +EXAMPLE + + ... + kfree (dev->private); /* before we lose the pointer */ + parport_unregister_device (dev); + ... + +SEE ALSO + +parport_unregister_driver + +parport_claim, parport_claim_or_block - claim the parallel port for a device +------------------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +int parport_claim (struct pardevice *dev); +int parport_claim_or_block (struct pardevice *dev); + +DESCRIPTION + +These functions attempt to gain control of the parallel port on which +'dev' is registered. 'parport_claim' does not block, but +'parport_claim_or_block' may do. (Put something here about blocking +interruptibly or non-interruptibly.) + +You should not try to claim a port that you have already claimed. + +RETURN VALUE + +A return value of zero indicates that the port was successfully +claimed, and the caller now has possession of the parallel port. + +If 'parport_claim_or_block' blocks before returning successfully, the +return value is positive. + +ERRORS + + -EAGAIN The port is unavailable at the moment, but another attempt + to claim it may succeed. + +SEE ALSO + +parport_release + +parport_release - release the parallel port +--------------- + +SYNOPSIS + +#include <linux/parport.h> + +void parport_release (struct pardevice *dev); + +DESCRIPTION + +Once a parallel port device has been claimed, it can be released using +'parport_release'. It cannot fail, but you should not release a +device that you do not have possession of. + +EXAMPLE + +static size_t write (struct pardevice *dev, const void *buf, + size_t len) +{ + ... + written = dev->port->ops->write_ecp_data (dev->port, buf, + len); + parport_release (dev); + ... +} + + +SEE ALSO + +change_mode, parport_claim, parport_claim_or_block, parport_yield + +parport_yield, parport_yield_blocking - temporarily release a parallel port +------------------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +int parport_yield (struct pardevice *dev) +int parport_yield_blocking (struct pardevice *dev); + +DESCRIPTION + +When a driver has control of a parallel port, it may allow another +driver to temporarily 'borrow' it. 'parport_yield' does not block; +'parport_yield_blocking' may do. + +RETURN VALUE + +A return value of zero indicates that the caller still owns the port +and the call did not block. + +A positive return value from 'parport_yield_blocking' indicates that +the caller still owns the port and the call blocked. + +A return value of -EAGAIN indicates that the caller no longer owns the +port, and it must be re-claimed before use. + +ERRORS + + -EAGAIN Ownership of the parallel port was given away. + +SEE ALSO + +parport_release + +parport_wait_peripheral - wait for status lines, up to 35ms +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +int parport_wait_peripheral (struct parport *port, + unsigned char mask, + unsigned char val); + +DESCRIPTION + +Wait for the status lines in mask to match the values in val. + +RETURN VALUE + + -EINTR a signal is pending + 0 the status lines in mask have values in val + 1 timed out while waiting (35ms elapsed) + +SEE ALSO + +parport_poll_peripheral + +parport_poll_peripheral - wait for status lines, in usec +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +int parport_poll_peripheral (struct parport *port, + unsigned char mask, + unsigned char val, + int usec); + +DESCRIPTION + +Wait for the status lines in mask to match the values in val. + +RETURN VALUE + + -EINTR a signal is pending + 0 the status lines in mask have values in val + 1 timed out while waiting (usec microseconds have elapsed) + +SEE ALSO + +parport_wait_peripheral + +parport_wait_event - wait for an event on a port +------------------ + +SYNOPSIS + +#include <linux/parport.h> + +int parport_wait_event (struct parport *port, signed long timeout) + +DESCRIPTION + +Wait for an event (e.g. interrupt) on a port. The timeout is in +jiffies. + +RETURN VALUE + + 0 success + <0 error (exit as soon as possible) + >0 timed out + +parport_negotiate - perform IEEE 1284 negotiation +----------------- + +SYNOPSIS + +#include <linux/parport.h> + +int parport_negotiate (struct parport *, int mode); + +DESCRIPTION + +Perform IEEE 1284 negotiation. + +RETURN VALUE + + 0 handshake OK; IEEE 1284 peripheral and mode available + -1 handshake failed; peripheral not compliant (or none present) + 1 handshake OK; IEEE 1284 peripheral present but mode not + available + +SEE ALSO + +parport_read, parport_write + +parport_read - read data from device +------------ + +SYNOPSIS + +#include <linux/parport.h> + +ssize_t parport_read (struct parport *, void *buf, size_t len); + +DESCRIPTION + +Read data from device in current IEEE 1284 transfer mode. This only +works for modes that support reverse data transfer. + +RETURN VALUE + +If negative, an error code; otherwise the number of bytes transferred. + +SEE ALSO + +parport_write, parport_negotiate + +parport_write - write data to device +------------- + +SYNOPSIS + +#include <linux/parport.h> + +ssize_t parport_write (struct parport *, const void *buf, size_t len); + +DESCRIPTION + +Write data to device in current IEEE 1284 transfer mode. This only +works for modes that support forward data transfer. + +RETURN VALUE + +If negative, an error code; otherwise the number of bytes transferred. + +SEE ALSO + +parport_read, parport_negotiate + +parport_open - register device for particular device number +------------ + +SYNOPSIS + +#include <linux/parport.h> + +struct pardevice *parport_open (int devnum, const char *name, + int (*pf) (void *), + void (*kf) (void *), + void (*irqf) (int, void *, + struct pt_regs *), + int flags, void *handle); + +DESCRIPTION + +This is like parport_register_device but takes a device number instead +of a pointer to a struct parport. + +RETURN VALUE + +See parport_register_device. If no device is associated with devnum, +NULL is returned. + +SEE ALSO + +parport_register_device + +parport_close - unregister device for particular device number +------------- + +SYNOPSIS + +#include <linux/parport.h> + +void parport_close (struct pardevice *dev); + +DESCRIPTION + +This is the equivalent of parport_unregister_device for parport_open. + +SEE ALSO + +parport_unregister_device, parport_open + +parport_device_id - obtain IEEE 1284 Device ID +----------------- + +SYNOPSIS + +#include <linux/parport.h> + +ssize_t parport_device_id (int devnum, char *buffer, size_t len); + +DESCRIPTION + +Obtains the IEEE 1284 Device ID associated with a given device. + +RETURN VALUE + +If negative, an error code; otherwise, the number of bytes of buffer +that contain the device ID. The format of the device ID is as +follows: + +[length][ID] + +The first two bytes indicate the inclusive length of the entire Device +ID, and are in big-endian order. The ID is a sequence of pairs of the +form: + +key:value; + +NOTES + +Many devices have ill-formed IEEE 1284 Device IDs. + +SEE ALSO + +parport_find_class, parport_find_device + +parport_device_coords - convert device number to device coordinates +------------------ + +SYNOPSIS + +#include <linux/parport.h> + +int parport_device_coords (int devnum, int *parport, int *mux, + int *daisy); + +DESCRIPTION + +Convert between device number (zero-based) and device coordinates +(port, multiplexor, daisy chain address). + +RETURN VALUE + +Zero on success, in which case the coordinates are (*parport, *mux, +*daisy). + +SEE ALSO + +parport_open, parport_device_id + +parport_find_class - find a device by its class +------------------ + +SYNOPSIS + +#include <linux/parport.h> + +typedef enum { + PARPORT_CLASS_LEGACY = 0, /* Non-IEEE1284 device */ + PARPORT_CLASS_PRINTER, + PARPORT_CLASS_MODEM, + PARPORT_CLASS_NET, + PARPORT_CLASS_HDC, /* Hard disk controller */ + PARPORT_CLASS_PCMCIA, + PARPORT_CLASS_MEDIA, /* Multimedia device */ + PARPORT_CLASS_FDC, /* Floppy disk controller */ + PARPORT_CLASS_PORTS, + PARPORT_CLASS_SCANNER, + PARPORT_CLASS_DIGCAM, + PARPORT_CLASS_OTHER, /* Anything else */ + PARPORT_CLASS_UNSPEC, /* No CLS field in ID */ + PARPORT_CLASS_SCSIADAPTER +} parport_device_class; + +int parport_find_class (parport_device_class cls, int from); + +DESCRIPTION + +Find a device by class. The search starts from device number from+1. + +RETURN VALUE + +The device number of the next device in that class, or -1 if no such +device exists. + +NOTES + +Example usage: + +int devnum = -1; +while ((devnum = parport_find_class (PARPORT_CLASS_DIGCAM, devnum)) != -1) { + struct pardevice *dev = parport_open (devnum, ...); + ... +} + +SEE ALSO + +parport_find_device, parport_open, parport_device_id + +parport_find_device - find a device by its class +------------------ + +SYNOPSIS + +#include <linux/parport.h> + +int parport_find_device (const char *mfg, const char *mdl, int from); + +DESCRIPTION + +Find a device by vendor and model. The search starts from device +number from+1. + +RETURN VALUE + +The device number of the next device matching the specifications, or +-1 if no such device exists. + +NOTES + +Example usage: + +int devnum = -1; +while ((devnum = parport_find_device ("IOMEGA", "ZIP+", devnum)) != -1) { + struct pardevice *dev = parport_open (devnum, ...); + ... +} + +SEE ALSO + +parport_find_class, parport_open, parport_device_id + +parport_set_timeout - set the inactivity timeout +------------------- + +SYNOPSIS + +#include <linux/parport.h> + +long parport_set_timeout (struct pardevice *dev, long inactivity); + +DESCRIPTION + +Set the inactivity timeout, in jiffies, for a registered device. The +previous timeout is returned. + +RETURN VALUE + +The previous timeout, in jiffies. + +NOTES + +Some of the port->ops functions for a parport may take time, owing to +delays at the peripheral. After the peripheral has not responded for +'inactivity' jiffies, a timeout will occur and the blocking function +will return. + +A timeout of 0 jiffies is a special case: the function must do as much +as it can without blocking or leaving the hardware in an unknown +state. If port operations are performed from within an interrupt +handler, for instance, a timeout of 0 jiffies should be used. + +Once set for a registered device, the timeout will remain at the set +value until set again. + +SEE ALSO + +port->ops->xxx_read/write_yyy + +PORT FUNCTIONS +-------------- + +The functions in the port->ops structure (struct parport_operations) +are provided by the low-level driver responsible for that port. + +port->ops->read_data - read the data register +-------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + unsigned char (*read_data) (struct parport *port); + ... +}; + +DESCRIPTION + +If port->modes contains the PARPORT_MODE_TRISTATE flag and the +PARPORT_CONTROL_DIRECTION bit in the control register is set, this +returns the value on the data pins. If port->modes contains the +PARPORT_MODE_TRISTATE flag and the PARPORT_CONTROL_DIRECTION bit is +not set, the return value _may_ be the last value written to the data +register. Otherwise the return value is undefined. + +SEE ALSO + +write_data, read_status, write_control + +port->ops->write_data - write the data register +--------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + void (*write_data) (struct parport *port, unsigned char d); + ... +}; + +DESCRIPTION + +Writes to the data register. May have side-effects (a STROBE pulse, +for instance). + +SEE ALSO + +read_data, read_status, write_control + +port->ops->read_status - read the status register +---------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + unsigned char (*read_status) (struct parport *port); + ... +}; + +DESCRIPTION + +Reads from the status register. This is a bitmask: + +- PARPORT_STATUS_ERROR (printer fault, "nFault") +- PARPORT_STATUS_SELECT (on-line, "Select") +- PARPORT_STATUS_PAPEROUT (no paper, "PError") +- PARPORT_STATUS_ACK (handshake, "nAck") +- PARPORT_STATUS_BUSY (busy, "Busy") + +There may be other bits set. + +SEE ALSO + +read_data, write_data, write_control + +port->ops->read_control - read the control register +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + unsigned char (*read_control) (struct parport *port); + ... +}; + +DESCRIPTION + +Returns the last value written to the control register (either from +write_control or frob_control). No port access is performed. + +SEE ALSO + +read_data, write_data, read_status, write_control + +port->ops->write_control - write the control register +------------------------ + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + void (*write_control) (struct parport *port, unsigned char s); + ... +}; + +DESCRIPTION + +Writes to the control register. This is a bitmask: + _______ +- PARPORT_CONTROL_STROBE (nStrobe) + _______ +- PARPORT_CONTROL_AUTOFD (nAutoFd) + _____ +- PARPORT_CONTROL_INIT (nInit) + _________ +- PARPORT_CONTROL_SELECT (nSelectIn) + +SEE ALSO + +read_data, write_data, read_status, frob_control + +port->ops->frob_control - write control register bits +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + unsigned char (*frob_control) (struct parport *port, + unsigned char mask, + unsigned char val); + ... +}; + +DESCRIPTION + +This is equivalent to reading from the control register, masking out +the bits in mask, exclusive-or'ing with the bits in val, and writing +the result to the control register. + +As some ports don't allow reads from the control port, a software copy +of its contents is maintained, so frob_control is in fact only one +port access. + +SEE ALSO + +read_data, write_data, read_status, write_control + +port->ops->enable_irq - enable interrupt generation +--------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + void (*enable_irq) (struct parport *port); + ... +}; + +DESCRIPTION + +The parallel port hardware is instructed to generate interrupts at +appropriate moments, although those moments are +architecture-specific. For the PC architecture, interrupts are +commonly generated on the rising edge of nAck. + +SEE ALSO + +disable_irq + +port->ops->disable_irq - disable interrupt generation +---------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + void (*disable_irq) (struct parport *port); + ... +}; + +DESCRIPTION + +The parallel port hardware is instructed not to generate interrupts. +The interrupt itself is not masked. + +SEE ALSO + +enable_irq + +port->ops->data_forward - enable data drivers +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + void (*data_forward) (struct parport *port); + ... +}; + +DESCRIPTION + +Enables the data line drivers, for 8-bit host-to-peripheral +communications. + +SEE ALSO + +data_reverse + +port->ops->data_reverse - tristate the buffer +----------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + void (*data_reverse) (struct parport *port); + ... +}; + +DESCRIPTION + +Places the data bus in a high impedance state, if port->modes has the +PARPORT_MODE_TRISTATE bit set. + +SEE ALSO + +data_forward + +port->ops->epp_write_data - write EPP data +------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*epp_write_data) (struct parport *port, const void *buf, + size_t len, int flags); + ... +}; + +DESCRIPTION + +Writes data in EPP mode, and returns the number of bytes written. + +The 'flags' parameter may be one or more of the following, +bitwise-or'ed together: + +PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and + 32-bit registers. However, if a transfer + times out, the return value may be unreliable. + +SEE ALSO + +epp_read_data, epp_write_addr, epp_read_addr + +port->ops->epp_read_data - read EPP data +------------------------ + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*epp_read_data) (struct parport *port, void *buf, + size_t len, int flags); + ... +}; + +DESCRIPTION + +Reads data in EPP mode, and returns the number of bytes read. + +The 'flags' parameter may be one or more of the following, +bitwise-or'ed together: + +PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and + 32-bit registers. However, if a transfer + times out, the return value may be unreliable. + +SEE ALSO + +epp_write_data, epp_write_addr, epp_read_addr + +port->ops->epp_write_addr - write EPP address +------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*epp_write_addr) (struct parport *port, + const void *buf, size_t len, int flags); + ... +}; + +DESCRIPTION + +Writes EPP addresses (8 bits each), and returns the number written. + +The 'flags' parameter may be one or more of the following, +bitwise-or'ed together: + +PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and + 32-bit registers. However, if a transfer + times out, the return value may be unreliable. + +(Does PARPORT_EPP_FAST make sense for this function?) + +SEE ALSO + +epp_write_data, epp_read_data, epp_read_addr + +port->ops->epp_read_addr - read EPP address +------------------------ + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*epp_read_addr) (struct parport *port, void *buf, + size_t len, int flags); + ... +}; + +DESCRIPTION + +Reads EPP addresses (8 bits each), and returns the number read. + +The 'flags' parameter may be one or more of the following, +bitwise-or'ed together: + +PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and + 32-bit registers. However, if a transfer + times out, the return value may be unreliable. + +(Does PARPORT_EPP_FAST make sense for this function?) + +SEE ALSO + +epp_write_data, epp_read_data, epp_write_addr + +port->ops->ecp_write_data - write a block of ECP data +------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*ecp_write_data) (struct parport *port, + const void *buf, size_t len, int flags); + ... +}; + +DESCRIPTION + +Writes a block of ECP data. The 'flags' parameter is ignored. + +RETURN VALUE + +The number of bytes written. + +SEE ALSO + +ecp_read_data, ecp_write_addr + +port->ops->ecp_read_data - read a block of ECP data +------------------------ + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*ecp_read_data) (struct parport *port, + void *buf, size_t len, int flags); + ... +}; + +DESCRIPTION + +Reads a block of ECP data. The 'flags' parameter is ignored. + +RETURN VALUE + +The number of bytes read. NB. There may be more unread data in a +FIFO. Is there a way of stunning the FIFO to prevent this? + +SEE ALSO + +ecp_write_block, ecp_write_addr + +port->ops->ecp_write_addr - write a block of ECP addresses +------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*ecp_write_addr) (struct parport *port, + const void *buf, size_t len, int flags); + ... +}; + +DESCRIPTION + +Writes a block of ECP addresses. The 'flags' parameter is ignored. + +RETURN VALUE + +The number of bytes written. + +NOTES + +This may use a FIFO, and if so shall not return until the FIFO is empty. + +SEE ALSO + +ecp_read_data, ecp_write_data + +port->ops->nibble_read_data - read a block of data in nibble mode +--------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*nibble_read_data) (struct parport *port, + void *buf, size_t len, int flags); + ... +}; + +DESCRIPTION + +Reads a block of data in nibble mode. The 'flags' parameter is ignored. + +RETURN VALUE + +The number of whole bytes read. + +SEE ALSO + +byte_read_data, compat_write_data + +port->ops->byte_read_data - read a block of data in byte mode +------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*byte_read_data) (struct parport *port, + void *buf, size_t len, int flags); + ... +}; + +DESCRIPTION + +Reads a block of data in byte mode. The 'flags' parameter is ignored. + +RETURN VALUE + +The number of bytes read. + +SEE ALSO + +nibble_read_data, compat_write_data + +port->ops->compat_write_data - write a block of data in compatibility mode +---------------------------- + +SYNOPSIS + +#include <linux/parport.h> + +struct parport_operations { + ... + size_t (*compat_write_data) (struct parport *port, + const void *buf, size_t len, int flags); + ... +}; + +DESCRIPTION + +Writes a block of data in compatibility mode. The 'flags' parameter +is ignored. + +RETURN VALUE + +The number of bytes written. + +SEE ALSO + +nibble_read_data, byte_read_data |