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Diffstat (limited to 'Documentation/parport-lowlevel.txt')
| -rw-r--r-- | Documentation/parport-lowlevel.txt | 1321 |
1 files changed, 841 insertions, 480 deletions
diff --git a/Documentation/parport-lowlevel.txt b/Documentation/parport-lowlevel.txt index 120eb20dbb09..0633d70ffda7 100644 --- a/Documentation/parport-lowlevel.txt +++ b/Documentation/parport-lowlevel.txt @@ -1,11 +1,12 @@ +=============================== PARPORT interface documentation -------------------------------- +=============================== -Time-stamp: <2000-02-24 13:30:20 twaugh> +:Time-stamp: <2000-02-24 13:30:20 twaugh> Described here are the following functions: -Global functions: +Global functions:: parport_register_driver parport_unregister_driver parport_enumerate @@ -31,7 +32,8 @@ Global functions: parport_set_timeout Port functions (can be overridden by low-level drivers): - SPP: + + SPP:: port->ops->read_data port->ops->write_data port->ops->read_status @@ -43,23 +45,23 @@ Port functions (can be overridden by low-level drivers): port->ops->data_forward port->ops->data_reverse - EPP: + EPP:: port->ops->epp_write_data port->ops->epp_read_data port->ops->epp_write_addr port->ops->epp_read_addr - ECP: + ECP:: port->ops->ecp_write_data port->ops->ecp_read_data port->ops->ecp_write_addr - Other: + 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 +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). @@ -70,14 +72,14 @@ 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 +``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. +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' +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 @@ -95,58 +97,63 @@ to cope with peripherals that only tenuously support IEEE 1284, a low-level driver specific function is provided, for altering 'fudge factors'. -GLOBAL FUNCTIONS ----------------- +Global functions +================ parport_register_driver - register a device driver with parport ------------------------ +--------------------------------------------------------------- SYNOPSIS +^^^^^^^^ + +:: -#include <linux/parport.h> + #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); + 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 ``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; - ... -}; +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 +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 @@ -169,297 +176,351 @@ hardware. It consists of flags which may be bitwise-ored together: 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. +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 +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 void lp_attach (struct parport *port) + { + ... + private = kmalloc (...); + dev[count++] = parport_register_device (...); + ... + } -static struct parport_driver lp_driver = { - "lp", - lp_attach, - lp_detach, - NULL /* always put NULL here */ -}; + static void lp_detach (struct parport *port) + { + ... + } -int lp_init (void) -{ - ... - if (parport_register_driver (&lp_driver)) { - /* Failed; nothing we can do. */ - return -EIO; + 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); + #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]); - ... -} + 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); + #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' +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, +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; + int detect_device (void) + { + struct parport *port; + + for (port = parport_enumerate (); + port != NULL; + port = port->next) { + /* Try to detect a device on the 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 *); + #include <linux/parport.h> -struct pardevice *parport_register_device(struct parport *port, - const char *name, - preempt_func preempt, - wakeup_func wakeup, - irq_func irq, - int flags, - void *handle); + 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 +(``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 +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 +``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 +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 +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 +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 +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 ``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: +``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: +The visible parts of the returned ``struct pardevice`` are:: -struct pardevice { - struct parport *port; /* Associated port */ - void *private; /* Device driver's 'handle' */ - ... -}; + 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 +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; -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; + 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> +:: + + #include <linux/parport.h> -void parport_unregister_device (struct pardevice *dev); + 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. +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 */ @@ -467,460 +528,602 @@ EXAMPLE ... SEE ALSO +^^^^^^^^ + parport_unregister_driver parport_claim, parport_claim_or_block - claim the parallel port for a device -------------------------------------- +---------------------------------------------------------------------------- SYNOPSIS +^^^^^^^^ + +:: -#include <linux/parport.h> + #include <linux/parport.h> -int parport_claim (struct pardevice *dev); -int parport_claim_or_block (struct pardevice *dev); + 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 +``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 +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> + #include <linux/parport.h> -void parport_release (struct pardevice *dev); + 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 +``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); - ... -} +:: + + 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> + #include <linux/parport.h> -int parport_yield (struct pardevice *dev) -int parport_yield_blocking (struct pardevice *dev); + 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. +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 +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> + #include <linux/parport.h> -int parport_wait_peripheral (struct parport *port, - unsigned char mask, - unsigned char val); + 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> + #include <linux/parport.h> -int parport_poll_peripheral (struct parport *port, - unsigned char mask, - unsigned char val, - int usec); + 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) + #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> + #include <linux/parport.h> -int parport_negotiate (struct parport *, int mode); + 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> + #include <linux/parport.h> -ssize_t parport_read (struct parport *, void *buf, size_t len); + 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> + #include <linux/parport.h> -ssize_t parport_write (struct parport *, const void *buf, size_t len); + 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); + #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> + #include <linux/parport.h> -void parport_close (struct pardevice *dev); + 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> + #include <linux/parport.h> -ssize_t parport_device_id (int devnum, char *buffer, size_t len); + 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: +follows:: -[length][ID] + [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: +form:: -key:value; + 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> + #include <linux/parport.h> -int parport_device_coords (int devnum, int *parport, int *mux, - int *daisy); + 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). +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); +^^^^^^^^ + +:: + + #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: +Example usage:: -int devnum = -1; -while ((devnum = parport_find_class (PARPORT_CLASS_DIGCAM, devnum)) != -1) { - struct pardevice *dev = parport_open (devnum, ...); - ... -} + 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); + #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: +Example usage:: -int devnum = -1; -while ((devnum = parport_find_device ("IOMEGA", "ZIP+", devnum)) != -1) { - struct pardevice *dev = parport_open (devnum, ...); - ... -} + 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> + #include <linux/parport.h> -long parport_set_timeout (struct pardevice *dev, long inactivity); + 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 +``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 @@ -932,29 +1135,37 @@ 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); - ... -}; + #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 @@ -964,45 +1175,59 @@ 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); - ... -}; + #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); - ... -}; + #include <linux/parport.h> + + struct parport_operations { + ... + unsigned char (*read_status) (struct parport *port); + ... + }; DESCRIPTION +^^^^^^^^^^^ Reads from the status register. This is a bitmask: @@ -1015,76 +1240,98 @@ Reads from the status register. This is a bitmask: 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); - ... -}; + #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); - ... -}; + #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) +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); - ... -}; + #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 @@ -1095,23 +1342,30 @@ 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); - ... -}; + #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 @@ -1119,353 +1373,460 @@ 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); - ... -}; + #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); - ... -}; + #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); - ... -}; + #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); - ... -}; + #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, +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); - ... -}; + #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, +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); - ... -}; + #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, +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); - ... -}; + #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, +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); - ... -}; + #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. +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); - ... -}; + #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. +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); - ... -}; + #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. +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); - ... -}; + #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. +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); - ... -}; + #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. +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); - ... -}; + #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 +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 |