Re: Driver core change request

Dmitry Torokhov
2004-10-21T07:16:16Z

On Tuesday 12 October 2004 01:29 am, Dmitry Torokhov wrote:
> For now I added:
>
> - "driver" default device attribute that produces name of currently bound
> driver uppon read.
> - bus->rebind_handler method that is called when someone writes to "driver"
> attribute and allows to perform bunctions like disconnecting device or
> rebinding it to alternative driver in bus-specific way.
> - "bind_mode" default device and driver attributes that can be "auto" or
> "manual". When device or driver marked as manual bind device_attach()
> and driver_attach() will ignore them. They are expected to be bound by
> bus->rebind_handler (via driver_probe_device()).
>
> I also renamed bus_match to driver_probe_device() and exported it, along
> with device_attach and driver_attach.
>
> Please let me know if its acceptable.
>

Greg,

Sorry for bothering you but cold you tell me if you are staisfied with the
patches or I need to look for some alternative. As an example of usage
please find my working copy of serio.c below.

Thanks!

--
Dmitry

/*
* The Serio abstraction module
*
* Copyright (c) 1999-2004 Vojtech Pavlik
* Copyright (c) 2004 Dmitry Torokhov
* Copyright (c) 2003 Daniele Bellucci
*/

/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Should you need to contact me, the author, you can do so either by
* e-mail - mail your message to <vojtech@ucw.cz>, or by paper mail:
* Vojtech Pavlik, Simunkova 1594, Prague 8, 182 00 Czech Republic
*/

#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/suspend.h>
#include <linux/slab.h>

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
MODULE_DESCRIPTION("Serio abstraction core");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(serio_interrupt);
EXPORT_SYMBOL(__serio_register_port);
EXPORT_SYMBOL(serio_unregister_port);
EXPORT_SYMBOL(__serio_unregister_port_delayed);
EXPORT_SYMBOL(serio_register_driver);
EXPORT_SYMBOL(serio_unregister_driver);
EXPORT_SYMBOL(serio_open);
EXPORT_SYMBOL(serio_close);
EXPORT_SYMBOL(serio_rescan);
EXPORT_SYMBOL(serio_reconnect);

/*
* serio_sem protects entire serio subsystem and is taken every time
* serio port or driver registrered or unregistered.
*/
static DECLARE_MUTEX(serio_sem);

static LIST_HEAD(serio_list);

struct bus_type serio_bus = {
.name = "serio",
};

static void serio_add_port(struct serio *serio);
static void serio_destroy_port(struct serio *serio);
static void serio_reconnect_port(struct serio *serio);
static void serio_disconnect_port(struct serio *serio);

/*
* Basic serio -> driver core mappings
*/

static void serio_bind_driver(struct serio *serio, struct serio_driver *drv)
{
down_write(&serio_bus.subsys.rwsem);
driver_probe_device(&drv->driver, &serio->dev);
up_write(&serio_bus.subsys.rwsem);
}

static void serio_release_driver(struct serio *serio)
{
down_write(&serio_bus.subsys.rwsem);
device_release_driver(&serio->dev);
up_write(&serio_bus.subsys.rwsem);
}

static void serio_find_driver(struct serio *serio)
{
down_write(&serio_bus.subsys.rwsem);
device_attach(&serio->dev);
up_write(&serio_bus.subsys.rwsem);
}

/*
* Serio event processing.
*/

struct serio_event {
int type;
struct serio *serio;
struct module *owner;
struct list_head node;
};

enum serio_event_type {
SERIO_RESCAN,
SERIO_RECONNECT,
SERIO_REGISTER_PORT,
SERIO_UNREGISTER_PORT,
};

static spinlock_t serio_event_lock = SPIN_LOCK_UNLOCKED; /* protects serio_event_list */
static LIST_HEAD(serio_event_list);
static DECLARE_WAIT_QUEUE_HEAD(serio_wait);
static DECLARE_COMPLETION(serio_exited);
static int serio_pid;

static void serio_queue_event(struct serio *serio, struct module *owner, int event_type)
{
unsigned long flags;
struct serio_event *event;

spin_lock_irqsave(&serio_event_lock, flags);

if ((event = kmalloc(sizeof(struct serio_event), GFP_ATOMIC))) {
__module_get(owner);

event->type = event_type;
event->serio = serio;
event->owner = owner;

list_add_tail(&event->node, &serio_event_list);
wake_up(&serio_wait);
} else
printk(KERN_ERR "serio: Not enough memory to queue event %d\n", event_type);

spin_unlock_irqrestore(&serio_event_lock, flags);
}

static struct serio_event *serio_get_event(void)
{
struct serio_event *event = NULL;
struct list_head *node;
unsigned long flags;

spin_lock_irqsave(&serio_event_lock, flags);

if (!list_empty(&serio_event_list)) {
node = serio_event_list.next;
event = container_of(node, struct serio_event, node);
list_del_init(node);
}

spin_unlock_irqrestore(&serio_event_lock, flags);

return event;
}

static void serio_handle_events(void)
{
struct serio_event *event;

down(&serio_sem);

while ((event = serio_get_event())) {

switch (event->type) {
case SERIO_REGISTER_PORT :
serio_add_port(event->serio);
serio_find_driver(event->serio);
break;

case SERIO_UNREGISTER_PORT :
serio_disconnect_port(event->serio);
serio_destroy_port(event->serio);
break;

case SERIO_RECONNECT :
serio_reconnect_port(event->serio);
break;

case SERIO_RESCAN :
serio_disconnect_port(event->serio);
serio_find_driver(event->serio);
break;
default:
break;
}

module_put(event->owner);
kfree(event);
}

up(&serio_sem);
}

/*
* Remove all events that have been submitted for a gicen serio port.
*/
static void serio_remove_pending_events(struct serio *serio)
{
struct list_head *node, *next;
struct serio_event *event;
unsigned long flags;

spin_lock_irqsave(&serio_event_lock, flags);

list_for_each_safe(node, next, &serio_event_list) {
event = list_entry(node, struct serio_event, node);
if (event->serio == serio) {
list_del_init(node);
kfree(event);
}
}

spin_unlock_irqrestore(&serio_event_lock, flags);
}

/*
* Destroy child serio port (if any) that has not been fully registered yet.
*
* Note that we rely on the fact that port can have only one child and therefore
* only one child registration request can be pending. Additionally, children
* are registered by driver's connect() handler so there can't be a grandchild
* pending registration together with a child.
*/
static struct serio *serio_get_pending_child(struct serio *parent)
{
struct serio_event *event;
struct serio *serio = NULL;
unsigned long flags;

spin_lock_irqsave(&serio_event_lock, flags);

list_for_each_entry(event, &serio_event_list, node) {
if (event->type == SERIO_REGISTER_PORT && event->serio->parent == parent) {
serio = event->serio;
break;
}
}

spin_unlock_irqrestore(&serio_event_lock, flags);
return serio;
}

static int serio_thread(void *nothing)
{
lock_kernel();
daemonize("kseriod");
allow_signal(SIGTERM);

do {
serio_handle_events();
wait_event_interruptible(serio_wait, !list_empty(&serio_event_list));
if (current->flags & PF_FREEZE)
refrigerator(PF_FREEZE);
} while (!signal_pending(current));

printk(KERN_DEBUG "serio: kseriod exiting\n");

unlock_kernel();
complete_and_exit(&serio_exited, 0);
}

/*
* Serio port operations
*/

static ssize_t serio_show_description(struct device *dev, char *buf)
{
struct serio *serio = to_serio_port(dev);
return sprintf(buf, "%s\n", serio->name);
}

static struct device_attribute serio_device_attrs[] = {
__ATTR(description, S_IRUGO, serio_show_description, NULL),
__ATTR_NULL
};

static void serio_release_port(struct device *dev)
{
struct serio *serio = to_serio_port(dev);

printk(KERN_INFO "serio: releasing %s\n", serio->name);
kfree(serio);
module_put(THIS_MODULE);
}

/*
* Prepare serio port for registration.
*/
static void serio_init_port(struct serio *serio)
{
static atomic_t serio_no = ATOMIC_INIT(0);

__module_get(THIS_MODULE);

spin_lock_init(&serio->lock);
init_MUTEX(&serio->drv_sem);
device_initialize(&serio->dev);
snprintf(serio->dev.bus_id, sizeof(serio->dev.bus_id),
"serio%d", atomic_inc_return(&serio_no) - 1);
serio->dev.bus = &serio_bus;
serio->dev.release = serio_release_port;
if (serio->parent)
serio->dev.parent = &serio->parent->dev;
}

/*
* Complete serio port registration.
* Driver core will attempt to find appropriate driver for the port.
*/
static void serio_add_port(struct serio *serio)
{
if (serio->parent) {
serio_pause_rx(serio->parent);
serio->parent->child = serio;
serio_continue_rx(serio->parent);
}

list_add_tail(&serio->node, &serio_list);
device_add(&serio->dev);
serio->registered = 1;
}

/*
* serio_destroy_port() completes deregistration process and removes
* port from the system.
*/
static void serio_destroy_port(struct serio *serio)
{
struct serio *child;

printk(KERN_INFO "serio: destroying port %s, cnt: %d\n", serio->name, atomic_read(&serio->dev.kobj.kref.refcount));
child = serio_get_pending_child(serio);
if (child) {
serio_remove_pending_events(child);
put_device(&child->dev);
}

if (serio->parent) {
serio_pause_rx(serio->parent);
serio->parent->child = NULL;
serio->parent = NULL;
serio_continue_rx(serio->parent);
}

if (serio->registered) {
printk(KERN_INFO "serio: destroying port %s (device_del)\n", serio->name);
device_del(&serio->dev);
list_del_init(&serio->node);
serio->registered = 0;
}

serio_remove_pending_events(serio);
printk(KERN_INFO "serio: destroying port %s (put_device)\n", serio->name);
put_device(&serio->dev);
}

/*
* Reconnect serio port and all its children (re-initialize attached devices)
*/
static void serio_reconnect_port(struct serio *serio)
{
do {
if (!serio->drv || !serio->drv->reconnect || serio->drv->reconnect(serio)) {
serio_disconnect_port(serio);
serio_find_driver(serio);
/* Ok, old children are now gone, we are done */
break;
}
serio = serio->child;
} while (serio);
}

/*
* serio_disconnect_port() unbinds a port from its driver. As a side effect
* all child ports are unbound and destroyed.
*/
static void serio_disconnect_port(struct serio *serio)
{
struct serio *s, *parent;

printk(KERN_INFO "serio: disconnecting port %s\n", serio->name);

if (serio->child) {
/*
* Children ports should be disconnected and destroyed
* first, staring with the leaf one, since we don't want
* to do recursion
*/
for (s = serio; s->child; s = s->child)
/* empty */;

do {
parent = s->parent;

printk(KERN_INFO "serio: releasing driver on child port %s\n", s->name);
serio_release_driver(s);
printk(KERN_INFO "serio: destroying port %s\n", s->name);
serio_destroy_port(s);
} while ((s = parent) != serio);
}

/*
* Ok, no children left, now disconnect this port
*/
printk(KERN_INFO "serio: releasing driver on port %s\n", serio->name);
serio_release_driver(serio);
}

void serio_rescan(struct serio *serio)
{
serio_queue_event(serio, NULL, SERIO_RESCAN);
}

void serio_reconnect(struct serio *serio)
{
serio_queue_event(serio, NULL, SERIO_RECONNECT);
}

/*
* Submits register request to kseriod for subsequent execution.
* Note that port registration is always asynchronous.
*/
void __serio_register_port(struct serio *serio, struct module *owner)
{
serio_init_port(serio);
serio_queue_event(serio, owner, SERIO_REGISTER_PORT);
}

/*
* Synchronously unregisters serio port.
*/
void serio_unregister_port(struct serio *serio)
{
down(&serio_sem);
serio_disconnect_port(serio);
serio_destroy_port(serio);
up(&serio_sem);
}

/*
* Submits unregister request to kseriod for subsequent execution.
* Can be used when it is not obvious whether the serio_sem is
* taken or not and when delayed execution is feasible.
*/
void __serio_unregister_port_delayed(struct serio *serio, struct module *owner)
{
serio_queue_event(serio, owner, SERIO_UNREGISTER_PORT);
}

/*
* Serio driver operations
*/

static ssize_t serio_driver_show_description(struct device_driver *drv, char *buf)
{
struct serio_driver *driver = to_serio_driver(drv);
return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
}

static struct driver_attribute serio_driver_attrs[] = {
__ATTR(description, S_IRUGO, serio_driver_show_description, NULL),
__ATTR_NULL
};

static int serio_driver_probe(struct device *dev)
{
struct serio *serio = to_serio_port(dev);
struct serio_driver *drv = to_serio_driver(dev->driver);

printk(KERN_INFO "serio: driver probe for %s and %s\n", drv->driver.name, serio->name);
drv->connect(serio, drv);
return serio->drv ? 0 : -ENODEV;
}

static int serio_driver_remove(struct device *dev)
{
struct serio *serio = to_serio_port(dev);
struct serio_driver *drv = to_serio_driver(dev->driver);

printk(KERN_INFO "serio: driver remove for %s and %s\n", drv->driver.name, serio->name);
drv->disconnect(serio);
return 0;
}

void serio_register_driver(struct serio_driver *drv)
{
down(&serio_sem);

drv->driver.bus = &serio_bus;
drv->driver.probe = serio_driver_probe;
drv->driver.remove = serio_driver_remove;
driver_register(&drv->driver);

up(&serio_sem);
}

void serio_unregister_driver(struct serio_driver *drv)
{
struct serio *serio;

down(&serio_sem);
drv->driver.manual_bind = 1; /* so serio_find_driver ignores it */

start_over:
list_for_each_entry(serio, &serio_list, node) {
if (serio->drv == drv) {
serio_disconnect_port(serio);
serio_find_driver(serio);
/* we could've deleted some ports, restart */
goto start_over;
}
}

driver_unregister(&drv->driver);
up(&serio_sem);
}

static int serio_rebind_driver(struct device *dev, const char *buf, size_t count)
{
struct serio *serio = to_serio_port(dev);
struct device_driver *drv;
int retval;

retval = down_interruptible(&serio_sem);
if (retval)
return retval;

if (!strncmp(buf, "none", count)) {
serio_disconnect_port(serio);
} else if (!strncmp(buf, "reconnect", count)) {
serio_reconnect_port(serio);
} else if (!strncmp(buf, "rescan", count)) {
serio_disconnect_port(serio);
serio_find_driver(serio);
} else if ((drv = driver_find(buf, &serio_bus)) != NULL) {
serio_disconnect_port(serio);
serio_bind_driver(serio, to_serio_driver(drv));
put_driver(drv);
} else {
retval = -EINVAL;
}

up(&serio_sem);

return retval;
}

static int serio_bus_match(struct device *dev, struct device_driver *drv)
{
/*
* For now we match everything as real checks are done in
* connect methods.
*/
return 1;
}

static void serio_set_drv(struct serio *serio, struct serio_driver *drv)
{
down(&serio->drv_sem);
serio_pause_rx(serio);
serio->drv = drv;
serio_continue_rx(serio);
up(&serio->drv_sem);
}

/* called from serio_driver->connect/disconnect methods under serio_sem */
int serio_open(struct serio *serio, struct serio_driver *drv)
{
serio_set_drv(serio, drv);

if (serio->open && serio->open(serio)) {
serio_set_drv(serio, NULL);
return -1;
}
return 0;
}

/* called from serio_driver->connect/disconnect methods under serio_sem */
void serio_close(struct serio *serio)
{
if (serio->close)
serio->close(serio);

serio_set_drv(serio, NULL);
}

irqreturn_t serio_interrupt(struct serio *serio,
unsigned char data, unsigned int dfl, struct pt_regs *regs)
{
unsigned long flags;
irqreturn_t ret = IRQ_NONE;

spin_lock_irqsave(&serio->lock, flags);

if (likely(serio->drv)) {
ret = serio->drv->interrupt(serio, data, dfl, regs);
} else {
if (!dfl) {
if ((serio->type != SERIO_8042 &&
serio->type != SERIO_8042_XL) || (data == 0xaa)) {
serio_rescan(serio);
ret = IRQ_HANDLED;
}
}
}

spin_unlock_irqrestore(&serio->lock, flags);

return ret;
}

static int __init serio_init(void)
{
if (!(serio_pid = kernel_thread(serio_thread, NULL, CLONE_KERNEL))) {
printk(KERN_ERR "serio: Failed to start kseriod\n");
return -1;
}

serio_bus.dev_attrs = serio_device_attrs;
serio_bus.drv_attrs = serio_driver_attrs;
serio_bus.match = serio_bus_match;
serio_bus.rebind_helper = serio_rebind_driver;
bus_register(&serio_bus);

return 0;
}

static void __exit serio_exit(void)
{
bus_unregister(&serio_bus);
kill_proc(serio_pid, SIGTERM, 1);
wait_for_completion(&serio_exited);
}

module_init(serio_init);
module_exit(serio_exit);