diff options
Diffstat (limited to 'drivers/parport/share.c')
| -rw-r--r-- | drivers/parport/share.c | 1014 |
1 files changed, 1014 insertions, 0 deletions
diff --git a/drivers/parport/share.c b/drivers/parport/share.c new file mode 100644 index 0000000..ae7becf --- /dev/null +++ b/drivers/parport/share.c @@ -0,0 +1,1014 @@ +/* $Id: parport_share.c,v 1.15 1998/01/11 12:06:17 philip Exp $ + * Parallel-port resource manager code. + * + * Authors: David Campbell <campbell@tirian.che.curtin.edu.au> + * Tim Waugh <tim@cyberelk.demon.co.uk> + * Jose Renau <renau@acm.org> + * Philip Blundell <philb@gnu.org> + * Andrea Arcangeli + * + * based on work by Grant Guenther <grant@torque.net> + * and Philip Blundell + * + * Any part of this program may be used in documents licensed under + * the GNU Free Documentation License, Version 1.1 or any later version + * published by the Free Software Foundation. + */ + +#undef PARPORT_DEBUG_SHARING /* undef for production */ + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/string.h> +#include <linux/threads.h> +#include <linux/parport.h> +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/interrupt.h> +#include <linux/ioport.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/sched.h> +#include <linux/kmod.h> + +#include <linux/spinlock.h> +#include <asm/irq.h> + +#undef PARPORT_PARANOID + +#define PARPORT_DEFAULT_TIMESLICE (HZ/5) + +unsigned long parport_default_timeslice = PARPORT_DEFAULT_TIMESLICE; +int parport_default_spintime = DEFAULT_SPIN_TIME; + +static LIST_HEAD(portlist); +static DEFINE_SPINLOCK(parportlist_lock); + +/* list of all allocated ports, sorted by ->number */ +static LIST_HEAD(all_ports); +static DEFINE_SPINLOCK(full_list_lock); + +static LIST_HEAD(drivers); + +static DECLARE_MUTEX(registration_lock); + +/* What you can do to a port that's gone away.. */ +static void dead_write_lines (struct parport *p, unsigned char b){} +static unsigned char dead_read_lines (struct parport *p) { return 0; } +static unsigned char dead_frob_lines (struct parport *p, unsigned char b, + unsigned char c) { return 0; } +static void dead_onearg (struct parport *p){} +static void dead_initstate (struct pardevice *d, struct parport_state *s) { } +static void dead_state (struct parport *p, struct parport_state *s) { } +static size_t dead_write (struct parport *p, const void *b, size_t l, int f) +{ return 0; } +static size_t dead_read (struct parport *p, void *b, size_t l, int f) +{ return 0; } +static struct parport_operations dead_ops = { + .write_data = dead_write_lines, /* data */ + .read_data = dead_read_lines, + + .write_control = dead_write_lines, /* control */ + .read_control = dead_read_lines, + .frob_control = dead_frob_lines, + + .read_status = dead_read_lines, /* status */ + + .enable_irq = dead_onearg, /* enable_irq */ + .disable_irq = dead_onearg, /* disable_irq */ + + .data_forward = dead_onearg, /* data_forward */ + .data_reverse = dead_onearg, /* data_reverse */ + + .init_state = dead_initstate, /* init_state */ + .save_state = dead_state, + .restore_state = dead_state, + + .epp_write_data = dead_write, /* epp */ + .epp_read_data = dead_read, + .epp_write_addr = dead_write, + .epp_read_addr = dead_read, + + .ecp_write_data = dead_write, /* ecp */ + .ecp_read_data = dead_read, + .ecp_write_addr = dead_write, + + .compat_write_data = dead_write, /* compat */ + .nibble_read_data = dead_read, /* nibble */ + .byte_read_data = dead_read, /* byte */ + + .owner = NULL, +}; + +/* Call attach(port) for each registered driver. */ +static void attach_driver_chain(struct parport *port) +{ + /* caller has exclusive registration_lock */ + struct parport_driver *drv; + list_for_each_entry(drv, &drivers, list) + drv->attach(port); +} + +/* Call detach(port) for each registered driver. */ +static void detach_driver_chain(struct parport *port) +{ + struct parport_driver *drv; + /* caller has exclusive registration_lock */ + list_for_each_entry(drv, &drivers, list) + drv->detach (port); +} + +/* Ask kmod for some lowlevel drivers. */ +static void get_lowlevel_driver (void) +{ + /* There is no actual module called this: you should set + * up an alias for modutils. */ + request_module ("parport_lowlevel"); +} + +/** + * parport_register_driver - register a parallel port device driver + * @drv: structure describing the driver + * + * This can be called by a parallel port device driver in order + * to receive notifications about ports being found in the + * system, as well as ports no longer available. + * + * The @drv structure is allocated by the caller and must not be + * deallocated until after calling parport_unregister_driver(). + * + * The driver's attach() function may block. The port that + * attach() is given will be valid for the duration of the + * callback, but if the driver wants to take a copy of the + * pointer it must call parport_get_port() to do so. Calling + * parport_register_device() on that port will do this for you. + * + * The driver's detach() function may block. The port that + * detach() is given will be valid for the duration of the + * callback, but if the driver wants to take a copy of the + * pointer it must call parport_get_port() to do so. + * + * Returns 0 on success. Currently it always succeeds. + **/ + +int parport_register_driver (struct parport_driver *drv) +{ + struct parport *port; + + if (list_empty(&portlist)) + get_lowlevel_driver (); + + down(®istration_lock); + list_for_each_entry(port, &portlist, list) + drv->attach(port); + list_add(&drv->list, &drivers); + up(®istration_lock); + + return 0; +} + +/** + * parport_unregister_driver - deregister a parallel port device driver + * @drv: structure describing the driver that was given to + * parport_register_driver() + * + * This should be called by a parallel port device driver that + * has registered itself using parport_register_driver() when it + * is about to be unloaded. + * + * When it returns, the driver's attach() routine will no longer + * be called, and for each port that attach() was called for, the + * detach() routine will have been called. + * + * All the driver's attach() and detach() calls are guaranteed to have + * finished by the time this function returns. + **/ + +void parport_unregister_driver (struct parport_driver *drv) +{ + struct parport *port; + + down(®istration_lock); + list_del_init(&drv->list); + list_for_each_entry(port, &portlist, list) + drv->detach(port); + up(®istration_lock); +} + +static void free_port (struct parport *port) +{ + int d; + spin_lock(&full_list_lock); + list_del(&port->full_list); + spin_unlock(&full_list_lock); + for (d = 0; d < 5; d++) { + if (port->probe_info[d].class_name) + kfree (port->probe_info[d].class_name); + if (port->probe_info[d].mfr) + kfree (port->probe_info[d].mfr); + if (port->probe_info[d].model) + kfree (port->probe_info[d].model); + if (port->probe_info[d].cmdset) + kfree (port->probe_info[d].cmdset); + if (port->probe_info[d].description) + kfree (port->probe_info[d].description); + } + + kfree(port->name); + kfree(port); +} + +/** + * parport_get_port - increment a port's reference count + * @port: the port + * + * This ensure's that a struct parport pointer remains valid + * until the matching parport_put_port() call. + **/ + +struct parport *parport_get_port (struct parport *port) +{ + atomic_inc (&port->ref_count); + return port; +} + +/** + * parport_put_port - decrement a port's reference count + * @port: the port + * + * This should be called once for each call to parport_get_port(), + * once the port is no longer needed. + **/ + +void parport_put_port (struct parport *port) +{ + if (atomic_dec_and_test (&port->ref_count)) + /* Can destroy it now. */ + free_port (port); + + return; +} + +/** + * parport_register_port - register a parallel port + * @base: base I/O address + * @irq: IRQ line + * @dma: DMA channel + * @ops: pointer to the port driver's port operations structure + * + * When a parallel port (lowlevel) driver finds a port that + * should be made available to parallel port device drivers, it + * should call parport_register_port(). The @base, @irq, and + * @dma parameters are for the convenience of port drivers, and + * for ports where they aren't meaningful needn't be set to + * anything special. They can be altered afterwards by adjusting + * the relevant members of the parport structure that is returned + * and represents the port. They should not be tampered with + * after calling parport_announce_port, however. + * + * If there are parallel port device drivers in the system that + * have registered themselves using parport_register_driver(), + * they are not told about the port at this time; that is done by + * parport_announce_port(). + * + * The @ops structure is allocated by the caller, and must not be + * deallocated before calling parport_remove_port(). + * + * If there is no memory to allocate a new parport structure, + * this function will return %NULL. + **/ + +struct parport *parport_register_port(unsigned long base, int irq, int dma, + struct parport_operations *ops) +{ + struct list_head *l; + struct parport *tmp; + int num; + int device; + char *name; + + tmp = kmalloc(sizeof(struct parport), GFP_KERNEL); + if (!tmp) { + printk(KERN_WARNING "parport: memory squeeze\n"); + return NULL; + } + + /* Init our structure */ + memset(tmp, 0, sizeof(struct parport)); + tmp->base = base; + tmp->irq = irq; + tmp->dma = dma; + tmp->muxport = tmp->daisy = tmp->muxsel = -1; + tmp->modes = 0; + INIT_LIST_HEAD(&tmp->list); + tmp->devices = tmp->cad = NULL; + tmp->flags = 0; + tmp->ops = ops; + tmp->physport = tmp; + memset (tmp->probe_info, 0, 5 * sizeof (struct parport_device_info)); + rwlock_init(&tmp->cad_lock); + spin_lock_init(&tmp->waitlist_lock); + spin_lock_init(&tmp->pardevice_lock); + tmp->ieee1284.mode = IEEE1284_MODE_COMPAT; + tmp->ieee1284.phase = IEEE1284_PH_FWD_IDLE; + init_MUTEX_LOCKED (&tmp->ieee1284.irq); /* actually a semaphore at 0 */ + tmp->spintime = parport_default_spintime; + atomic_set (&tmp->ref_count, 1); + INIT_LIST_HEAD(&tmp->full_list); + + name = kmalloc(15, GFP_KERNEL); + if (!name) { + printk(KERN_ERR "parport: memory squeeze\n"); + kfree(tmp); + return NULL; + } + /* Search for the lowest free parport number. */ + + spin_lock(&full_list_lock); + for (l = all_ports.next, num = 0; l != &all_ports; l = l->next, num++) { + struct parport *p = list_entry(l, struct parport, full_list); + if (p->number != num) + break; + } + tmp->portnum = tmp->number = num; + list_add_tail(&tmp->full_list, l); + spin_unlock(&full_list_lock); + + /* + * Now that the portnum is known finish doing the Init. + */ + sprintf(name, "parport%d", tmp->portnum = tmp->number); + tmp->name = name; + + for (device = 0; device < 5; device++) + /* assume the worst */ + tmp->probe_info[device].class = PARPORT_CLASS_LEGACY; + + tmp->waithead = tmp->waittail = NULL; + + return tmp; +} + +/** + * parport_announce_port - tell device drivers about a parallel port + * @port: parallel port to announce + * + * After a port driver has registered a parallel port with + * parport_register_port, and performed any necessary + * initialisation or adjustments, it should call + * parport_announce_port() in order to notify all device drivers + * that have called parport_register_driver(). Their attach() + * functions will be called, with @port as the parameter. + **/ + +void parport_announce_port (struct parport *port) +{ + int i; + +#ifdef CONFIG_PARPORT_1284 + /* Analyse the IEEE1284.3 topology of the port. */ + parport_daisy_init(port); +#endif + + parport_proc_register(port); + down(®istration_lock); + spin_lock_irq(&parportlist_lock); + list_add_tail(&port->list, &portlist); + for (i = 1; i < 3; i++) { + struct parport *slave = port->slaves[i-1]; + if (slave) + list_add_tail(&slave->list, &portlist); + } + spin_unlock_irq(&parportlist_lock); + + /* Let drivers know that new port(s) has arrived. */ + attach_driver_chain (port); + for (i = 1; i < 3; i++) { + struct parport *slave = port->slaves[i-1]; + if (slave) + attach_driver_chain(slave); + } + up(®istration_lock); +} + +/** + * parport_remove_port - deregister a parallel port + * @port: parallel port to deregister + * + * When a parallel port driver is forcibly unloaded, or a + * parallel port becomes inaccessible, the port driver must call + * this function in order to deal with device drivers that still + * want to use it. + * + * The parport structure associated with the port has its + * operations structure replaced with one containing 'null' + * operations that return errors or just don't do anything. + * + * Any drivers that have registered themselves using + * parport_register_driver() are notified that the port is no + * longer accessible by having their detach() routines called + * with @port as the parameter. + **/ + +void parport_remove_port(struct parport *port) +{ + int i; + + down(®istration_lock); + + /* Spread the word. */ + detach_driver_chain (port); + +#ifdef CONFIG_PARPORT_1284 + /* Forget the IEEE1284.3 topology of the port. */ + parport_daisy_fini(port); + for (i = 1; i < 3; i++) { + struct parport *slave = port->slaves[i-1]; + if (!slave) + continue; + detach_driver_chain(slave); + parport_daisy_fini(slave); + } +#endif + + port->ops = &dead_ops; + spin_lock(&parportlist_lock); + list_del_init(&port->list); + for (i = 1; i < 3; i++) { + struct parport *slave = port->slaves[i-1]; + if (slave) + list_del_init(&slave->list); + } + spin_unlock(&parportlist_lock); + + up(®istration_lock); + + parport_proc_unregister(port); + + for (i = 1; i < 3; i++) { + struct parport *slave = port->slaves[i-1]; + if (slave) + parport_put_port(slave); + } +} + +/** + * parport_register_device - register a device on a parallel port + * @port: port to which the device is attached + * @name: a name to refer to the device + * @pf: preemption callback + * @kf: kick callback (wake-up) + * @irq_func: interrupt handler + * @flags: registration flags + * @handle: data for callback functions + * + * This function, called by parallel port device drivers, + * declares that a device is connected to a port, and tells the + * system all it needs to know. + * + * The @name is allocated by the caller and must not be + * deallocated until the caller calls @parport_unregister_device + * for that device. + * + * The preemption callback function, @pf, is called when this + * device driver has claimed access to the port but another + * device driver wants to use it. It is given @handle as its + * parameter, and should return zero if it is willing for the + * system to release the port to another driver on its behalf. + * If it wants to keep control of the port it should return + * non-zero, and no action will be taken. It is good manners for + * the driver to try to release the port at the earliest + * opportunity after its preemption callback rejects a preemption + * attempt. Note that if a preemption callback is happy for + * preemption to go ahead, there is no need to release the port; + * it is done automatically. This function may not block, as it + * may be called from interrupt context. If the device driver + * does not support preemption, @pf can be %NULL. + * + * The wake-up ("kick") callback function, @kf, is called when + * the port is available to be claimed for exclusive access; that + * is, parport_claim() is guaranteed to succeed when called from + * inside the wake-up callback function. If the driver wants to + * claim the port it should do so; otherwise, it need not take + * any action. This function may not block, as it may be called + * from interrupt context. If the device driver does not want to + * be explicitly invited to claim the port in this way, @kf can + * be %NULL. + * + * The interrupt handler, @irq_func, is called when an interrupt + * arrives from the parallel port. Note that if a device driver + * wants to use interrupts it should use parport_enable_irq(), + * and can also check the irq member of the parport structure + * representing the port. + * + * The parallel port (lowlevel) driver is the one that has called + * request_irq() and whose interrupt handler is called first. + * This handler does whatever needs to be done to the hardware to + * acknowledge the interrupt (for PC-style ports there is nothing + * special to be done). It then tells the IEEE 1284 code about + * the interrupt, which may involve reacting to an IEEE 1284 + * event depending on the current IEEE 1284 phase. After this, + * it calls @irq_func. Needless to say, @irq_func will be called + * from interrupt context, and may not block. + * + * The %PARPORT_DEV_EXCL flag is for preventing port sharing, and + * so should only be used when sharing the port with other device + * drivers is impossible and would lead to incorrect behaviour. + * Use it sparingly! Normally, @flags will be zero. + * + * This function returns a pointer to a structure that represents + * the device on the port, or %NULL if there is not enough memory + * to allocate space for that structure. + **/ + +struct pardevice * +parport_register_device(struct parport *port, const char *name, + int (*pf)(void *), void (*kf)(void *), + void (*irq_func)(int, void *, struct pt_regs *), + int flags, void *handle) +{ + struct pardevice *tmp; + + if (port->physport->flags & PARPORT_FLAG_EXCL) { + /* An exclusive device is registered. */ + printk (KERN_DEBUG "%s: no more devices allowed\n", + port->name); + return NULL; + } + + if (flags & PARPORT_DEV_LURK) { + if (!pf || !kf) { + printk(KERN_INFO "%s: refused to register lurking device (%s) without callbacks\n", port->name, name); + return NULL; + } + } + + /* We up our own module reference count, and that of the port + on which a device is to be registered, to ensure that + neither of us gets unloaded while we sleep in (e.g.) + kmalloc. + */ + if (!try_module_get(port->ops->owner)) { + return NULL; + } + + parport_get_port (port); + + tmp = kmalloc(sizeof(struct pardevice), GFP_KERNEL); + if (tmp == NULL) { + printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name); + goto out; + } + + tmp->state = kmalloc(sizeof(struct parport_state), GFP_KERNEL); + if (tmp->state == NULL) { + printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name); + goto out_free_pardevice; + } + + tmp->name = name; + tmp->port = port; + tmp->daisy = -1; + tmp->preempt = pf; + tmp->wakeup = kf; + tmp->private = handle; + tmp->flags = flags; + tmp->irq_func = irq_func; + tmp->waiting = 0; + tmp->timeout = 5 * HZ; + + /* Chain this onto the list */ + tmp->prev = NULL; + /* + * This function must not run from an irq handler so we don' t need + * to clear irq on the local CPU. -arca + */ + spin_lock(&port->physport->pardevice_lock); + + if (flags & PARPORT_DEV_EXCL) { + if (port->physport->devices) { + spin_unlock (&port->physport->pardevice_lock); + printk (KERN_DEBUG + "%s: cannot grant exclusive access for " + "device %s\n", port->name, name); + goto out_free_all; + } + port->flags |= PARPORT_FLAG_EXCL; + } + + tmp->next = port->physport->devices; + wmb(); /* Make sure that tmp->next is written before it's + added to the list; see comments marked 'no locking + required' */ + if (port->physport->devices) + port->physport->devices->prev = tmp; + port->physport->devices = tmp; + spin_unlock(&port->physport->pardevice_lock); + + init_waitqueue_head(&tmp->wait_q); + tmp->timeslice = parport_default_timeslice; + tmp->waitnext = tmp->waitprev = NULL; + + /* + * This has to be run as last thing since init_state may need other + * pardevice fields. -arca + */ + port->ops->init_state(tmp, tmp->state); + parport_device_proc_register(tmp); + return tmp; + + out_free_all: + kfree (tmp->state); + out_free_pardevice: + kfree (tmp); + out: + parport_put_port (port); + module_put(port->ops->owner); + + return NULL; +} + +/** + * parport_unregister_device - deregister a device on a parallel port + * @dev: pointer to structure representing device + * + * This undoes the effect of parport_register_device(). + **/ + +void parport_unregister_device(struct pardevice *dev) +{ + struct parport *port; + +#ifdef PARPORT_PARANOID + if (dev == NULL) { + printk(KERN_ERR "parport_unregister_device: passed NULL\n"); + return; + } +#endif + + parport_device_proc_unregister(dev); + + port = dev->port->physport; + + if (port->cad == dev) { + printk(KERN_DEBUG "%s: %s forgot to release port\n", + port->name, dev->name); + parport_release (dev); + } + + spin_lock(&port->pardevice_lock); + if (dev->next) + dev->next->prev = dev->prev; + if (dev->prev) + dev->prev->next = dev->next; + else + port->devices = dev->next; + + if (dev->flags & PARPORT_DEV_EXCL) + port->flags &= ~PARPORT_FLAG_EXCL; + + spin_unlock(&port->pardevice_lock); + + /* Make sure we haven't left any pointers around in the wait + * list. */ + spin_lock (&port->waitlist_lock); + if (dev->waitprev || dev->waitnext || port->waithead == dev) { + if (dev->waitprev) + dev->waitprev->waitnext = dev->waitnext; + else + port->waithead = dev->waitnext; + if (dev->waitnext) + dev->waitnext->waitprev = dev->waitprev; + else + port->waittail = dev->waitprev; + } + spin_unlock (&port->waitlist_lock); + + kfree(dev->state); + kfree(dev); + + module_put(port->ops->owner); + parport_put_port (port); +} + +/** + * parport_find_number - find a parallel port by number + * @number: parallel port number + * + * This returns the parallel port with the specified number, or + * %NULL if there is none. + * + * There is an implicit parport_get_port() done already; to throw + * away the reference to the port that parport_find_number() + * gives you, use parport_put_port(). + */ + +struct parport *parport_find_number (int number) +{ + struct parport *port, *result = NULL; + + if (list_empty(&portlist)) + get_lowlevel_driver (); + + spin_lock (&parportlist_lock); + list_for_each_entry(port, &portlist, list) { + if (port->number == number) { + result = parport_get_port (port); + break; + } + } + spin_unlock (&parportlist_lock); + return result; +} + +/** + * parport_find_base - find a parallel port by base address + * @base: base I/O address + * + * This returns the parallel port with the specified base + * address, or %NULL if there is none. + * + * There is an implicit parport_get_port() done already; to throw + * away the reference to the port that parport_find_base() + * gives you, use parport_put_port(). + */ + +struct parport *parport_find_base (unsigned long base) +{ + struct parport *port, *result = NULL; + + if (list_empty(&portlist)) + get_lowlevel_driver (); + + spin_lock (&parportlist_lock); + list_for_each_entry(port, &portlist, list) { + if (port->base == base) { + result = parport_get_port (port); + break; + } + } + spin_unlock (&parportlist_lock); + return result; +} + +/** + * parport_claim - claim access to a parallel port device + * @dev: pointer to structure representing a device on the port + * + * This function will not block and so can be used from interrupt + * context. If parport_claim() succeeds in claiming access to + * the port it returns zero and the port is available to use. It + * may fail (returning non-zero) if the port is in use by another + * driver and that driver is not willing to relinquish control of + * the port. + **/ + +int parport_claim(struct pardevice *dev) +{ + struct pardevice *oldcad; + struct parport *port = dev->port->physport; + unsigned long flags; + + if (port->cad == dev) { + printk(KERN_INFO "%s: %s already owner\n", + dev->port->name,dev->name); + return 0; + } + + /* Preempt any current device */ + write_lock_irqsave (&port->cad_lock, flags); + if ((oldcad = port->cad) != NULL) { + if (oldcad->preempt) { + if (oldcad->preempt(oldcad->private)) + goto blocked; + port->ops->save_state(port, dev->state); + } else + goto blocked; + + if (port->cad != oldcad) { + /* I think we'll actually deadlock rather than + get here, but just in case.. */ + printk(KERN_WARNING + "%s: %s released port when preempted!\n", + port->name, oldcad->name); + if (port->cad) + goto blocked; + } + } + + /* Can't fail from now on, so mark ourselves as no longer waiting. */ + if (dev->waiting & 1) { + dev->waiting = 0; + + /* Take ourselves out of the wait list again. */ + spin_lock_irq (&port->waitlist_lock); + if (dev->waitprev) + dev->waitprev->waitnext = dev->waitnext; + else + port->waithead = dev->waitnext; + if (dev->waitnext) + dev->waitnext->waitprev = dev->waitprev; + else + port->waittail = dev->waitprev; + spin_unlock_irq (&port->waitlist_lock); + dev->waitprev = dev->waitnext = NULL; + } + + /* Now we do the change of devices */ + port->cad = dev; + +#ifdef CONFIG_PARPORT_1284 + /* If it's a mux port, select it. */ + if (dev->port->muxport >= 0) { + /* FIXME */ + port->muxsel = dev->port->muxport; + } + + /* If it's a daisy chain device, select it. */ + if (dev->daisy >= 0) { + /* This could be lazier. */ + if (!parport_daisy_select (port, dev->daisy, + IEEE1284_MODE_COMPAT)) + port->daisy = dev->daisy; + } +#endif /* IEEE1284.3 support */ + + /* Restore control registers */ + port->ops->restore_state(port, dev->state); + write_unlock_irqrestore(&port->cad_lock, flags); + dev->time = jiffies; + return 0; + +blocked: + /* If this is the first time we tried to claim the port, register an + interest. This is only allowed for devices sleeping in + parport_claim_or_block(), or those with a wakeup function. */ + + /* The cad_lock is still held for writing here */ + if (dev->waiting & 2 || dev->wakeup) { + spin_lock (&port->waitlist_lock); + if (test_and_set_bit(0, &dev->waiting) == 0) { + /* First add ourselves to the end of the wait list. */ + dev->waitnext = NULL; + dev->waitprev = port->waittail; + if (port->waittail) { + port->waittail->waitnext = dev; + port->waittail = dev; + } else + port->waithead = port->waittail = dev; + } + spin_unlock (&port->waitlist_lock); + } + write_unlock_irqrestore (&port->cad_lock, flags); + return -EAGAIN; +} + +/** + * parport_claim_or_block - claim access to a parallel port device + * @dev: pointer to structure representing a device on the port + * + * This behaves like parport_claim(), but will block if necessary + * to wait for the port to be free. A return value of 1 + * indicates that it slept; 0 means that it succeeded without + * needing to sleep. A negative error code indicates failure. + **/ + +int parport_claim_or_block(struct pardevice *dev) +{ + int r; + + /* Signal to parport_claim() that we can wait even without a + wakeup function. */ + dev->waiting = 2; + + /* Try to claim the port. If this fails, we need to sleep. */ + r = parport_claim(dev); + if (r == -EAGAIN) { +#ifdef PARPORT_DEBUG_SHARING + printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n", dev->name); +#endif + /* + * FIXME!!! Use the proper locking for dev->waiting, + * and make this use the "wait_event_interruptible()" + * interfaces. The cli/sti that used to be here + * did nothing. + * + * See also parport_release() + */ + + /* If dev->waiting is clear now, an interrupt + gave us the port and we would deadlock if we slept. */ + if (dev->waiting) { + interruptible_sleep_on (&dev->wait_q); + if (signal_pending (current)) { + return -EINTR; + } + r = 1; + } else { + r = 0; +#ifdef PARPORT_DEBUG_SHARING + printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n", + dev->name); +#endif + } + +#ifdef PARPORT_DEBUG_SHARING + if (dev->port->physport->cad != dev) + printk(KERN_DEBUG "%s: exiting parport_claim_or_block " + "but %s owns port!\n", dev->name, + dev->port->physport->cad ? + dev->port->physport->cad->name:"nobody"); +#endif + } + dev->waiting = 0; + return r; +} + +/** + * parport_release - give up access to a parallel port device + * @dev: pointer to structure representing parallel port device + * + * This function cannot fail, but it should not be called without + * the port claimed. Similarly, if the port is already claimed + * you should not try claiming it again. + **/ + +void parport_release(struct pardevice *dev) +{ + struct parport *port = dev->port->physport; + struct pardevice *pd; + unsigned long flags; + + /* Make sure that dev is the current device */ + write_lock_irqsave(&port->cad_lock, flags); + if (port->cad != dev) { + write_unlock_irqrestore (&port->cad_lock, flags); + printk(KERN_WARNING "%s: %s tried to release parport " + "when not owner\n", port->name, dev->name); + return; + } + +#ifdef CONFIG_PARPORT_1284 + /* If this is on a mux port, deselect it. */ + if (dev->port->muxport >= 0) { + /* FIXME */ + port->muxsel = -1; + } + + /* If this is a daisy device, deselect it. */ + if (dev->daisy >= 0) { + parport_daisy_deselect_all (port); + port->daisy = -1; + } +#endif + + port->cad = NULL; + write_unlock_irqrestore(&port->cad_lock, flags); + + /* Save control registers */ + port->ops->save_state(port, dev->state); + + /* If anybody is waiting, find out who's been there longest and + then wake them up. (Note: no locking required) */ + /* !!! LOCKING IS NEEDED HERE */ + for (pd = port->waithead; pd; pd = pd->waitnext) { + if (pd->waiting & 2) { /* sleeping in claim_or_block */ + parport_claim(pd); + if (waitqueue_active(&pd->wait_q)) + wake_up_interruptible(&pd->wait_q); + return; + } else if (pd->wakeup) { + pd->wakeup(pd->private); + if (dev->port->cad) /* racy but no matter */ + return; + } else { + printk(KERN_ERR "%s: don't know how to wake %s\n", port->name, pd->name); + } + } + + /* Nobody was waiting, so walk the list to see if anyone is + interested in being woken up. (Note: no locking required) */ + /* !!! LOCKING IS NEEDED HERE */ + for (pd = port->devices; (port->cad == NULL) && pd; pd = pd->next) { + if (pd->wakeup && pd != dev) + pd->wakeup(pd->private); + } +} + +/* Exported symbols for modules. */ + +EXPORT_SYMBOL(parport_claim); +EXPORT_SYMBOL(parport_claim_or_block); +EXPORT_SYMBOL(parport_release); +EXPORT_SYMBOL(parport_register_port); +EXPORT_SYMBOL(parport_announce_port); +EXPORT_SYMBOL(parport_remove_port); +EXPORT_SYMBOL(parport_register_driver); +EXPORT_SYMBOL(parport_unregister_driver); +EXPORT_SYMBOL(parport_register_device); +EXPORT_SYMBOL(parport_unregister_device); +EXPORT_SYMBOL(parport_put_port); +EXPORT_SYMBOL(parport_find_number); +EXPORT_SYMBOL(parport_find_base); + +MODULE_LICENSE("GPL"); |