kernel-ark/drivers/input/serio/libps2.c
David Howells 65f27f3844 WorkStruct: Pass the work_struct pointer instead of context data
Pass the work_struct pointer to the work function rather than context data.
The work function can use container_of() to work out the data.

For the cases where the container of the work_struct may go away the moment the
pending bit is cleared, it is made possible to defer the release of the
structure by deferring the clearing of the pending bit.

To make this work, an extra flag is introduced into the management side of the
work_struct.  This governs auto-release of the structure upon execution.

Ordinarily, the work queue executor would release the work_struct for further
scheduling or deallocation by clearing the pending bit prior to jumping to the
work function.  This means that, unless the driver makes some guarantee itself
that the work_struct won't go away, the work function may not access anything
else in the work_struct or its container lest they be deallocated..  This is a
problem if the auxiliary data is taken away (as done by the last patch).

However, if the pending bit is *not* cleared before jumping to the work
function, then the work function *may* access the work_struct and its container
with no problems.  But then the work function must itself release the
work_struct by calling work_release().

In most cases, automatic release is fine, so this is the default.  Special
initiators exist for the non-auto-release case (ending in _NAR).


Signed-Off-By: David Howells <dhowells@redhat.com>
2006-11-22 14:55:48 +00:00

388 lines
8.9 KiB
C

/*
* PS/2 driver library
*
* Copyright (c) 1999-2002 Vojtech Pavlik
* Copyright (c) 2004 Dmitry Torokhov
*/
/*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/init.h>
#include <linux/libps2.h>
#define DRIVER_DESC "PS/2 driver library"
MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
MODULE_DESCRIPTION("PS/2 driver library");
MODULE_LICENSE("GPL");
/* Work structure to schedule execution of a command */
struct ps2work {
struct work_struct work;
struct ps2dev *ps2dev;
int command;
unsigned char param[0];
};
/*
* ps2_sendbyte() sends a byte to the device and waits for acknowledge.
* It doesn't handle retransmission, though it could - because if there
* is a need for retransmissions device has to be replaced anyway.
*
* ps2_sendbyte() can only be called from a process context.
*/
int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout)
{
serio_pause_rx(ps2dev->serio);
ps2dev->nak = 1;
ps2dev->flags |= PS2_FLAG_ACK;
serio_continue_rx(ps2dev->serio);
if (serio_write(ps2dev->serio, byte) == 0)
wait_event_timeout(ps2dev->wait,
!(ps2dev->flags & PS2_FLAG_ACK),
msecs_to_jiffies(timeout));
serio_pause_rx(ps2dev->serio);
ps2dev->flags &= ~PS2_FLAG_ACK;
serio_continue_rx(ps2dev->serio);
return -ps2dev->nak;
}
EXPORT_SYMBOL(ps2_sendbyte);
/*
* ps2_drain() waits for device to transmit requested number of bytes
* and discards them.
*/
void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
{
if (maxbytes > sizeof(ps2dev->cmdbuf)) {
WARN_ON(1);
maxbytes = sizeof(ps2dev->cmdbuf);
}
mutex_lock(&ps2dev->cmd_mutex);
serio_pause_rx(ps2dev->serio);
ps2dev->flags = PS2_FLAG_CMD;
ps2dev->cmdcnt = maxbytes;
serio_continue_rx(ps2dev->serio);
wait_event_timeout(ps2dev->wait,
!(ps2dev->flags & PS2_FLAG_CMD),
msecs_to_jiffies(timeout));
mutex_unlock(&ps2dev->cmd_mutex);
}
EXPORT_SYMBOL(ps2_drain);
/*
* ps2_is_keyboard_id() checks received ID byte against the list of
* known keyboard IDs.
*/
int ps2_is_keyboard_id(char id_byte)
{
const static char keyboard_ids[] = {
0xab, /* Regular keyboards */
0xac, /* NCD Sun keyboard */
0x2b, /* Trust keyboard, translated */
0x5d, /* Trust keyboard */
0x60, /* NMB SGI keyboard, translated */
0x47, /* NMB SGI keyboard */
};
return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
}
EXPORT_SYMBOL(ps2_is_keyboard_id);
/*
* ps2_adjust_timeout() is called after receiving 1st byte of command
* response and tries to reduce remaining timeout to speed up command
* completion.
*/
static int ps2_adjust_timeout(struct ps2dev *ps2dev, int command, int timeout)
{
switch (command) {
case PS2_CMD_RESET_BAT:
/*
* Device has sent the first response byte after
* reset command, reset is thus done, so we can
* shorten the timeout.
* The next byte will come soon (keyboard) or not
* at all (mouse).
*/
if (timeout > msecs_to_jiffies(100))
timeout = msecs_to_jiffies(100);
break;
case PS2_CMD_GETID:
/*
* Microsoft Natural Elite keyboard responds to
* the GET ID command as it were a mouse, with
* a single byte. Fail the command so atkbd will
* use alternative probe to detect it.
*/
if (ps2dev->cmdbuf[1] == 0xaa) {
serio_pause_rx(ps2dev->serio);
ps2dev->flags = 0;
serio_continue_rx(ps2dev->serio);
timeout = 0;
}
/*
* If device behind the port is not a keyboard there
* won't be 2nd byte of ID response.
*/
if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
serio_pause_rx(ps2dev->serio);
ps2dev->flags = ps2dev->cmdcnt = 0;
serio_continue_rx(ps2dev->serio);
timeout = 0;
}
break;
default:
break;
}
return timeout;
}
/*
* ps2_command() sends a command and its parameters to the mouse,
* then waits for the response and puts it in the param array.
*
* ps2_command() can only be called from a process context
*/
int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
{
int timeout;
int send = (command >> 12) & 0xf;
int receive = (command >> 8) & 0xf;
int rc = -1;
int i;
if (receive > sizeof(ps2dev->cmdbuf)) {
WARN_ON(1);
return -1;
}
if (send && !param) {
WARN_ON(1);
return -1;
}
mutex_lock(&ps2dev->cmd_mutex);
serio_pause_rx(ps2dev->serio);
ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
ps2dev->cmdcnt = receive;
if (receive && param)
for (i = 0; i < receive; i++)
ps2dev->cmdbuf[(receive - 1) - i] = param[i];
serio_continue_rx(ps2dev->serio);
/*
* Some devices (Synaptics) peform the reset before
* ACKing the reset command, and so it can take a long
* time before the ACK arrrives.
*/
if (ps2_sendbyte(ps2dev, command & 0xff,
command == PS2_CMD_RESET_BAT ? 1000 : 200))
goto out;
for (i = 0; i < send; i++)
if (ps2_sendbyte(ps2dev, param[i], 200))
goto out;
/*
* The reset command takes a long time to execute.
*/
timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
timeout = wait_event_timeout(ps2dev->wait,
!(ps2dev->flags & PS2_FLAG_CMD1), timeout);
if (ps2dev->cmdcnt && timeout > 0) {
timeout = ps2_adjust_timeout(ps2dev, command, timeout);
wait_event_timeout(ps2dev->wait,
!(ps2dev->flags & PS2_FLAG_CMD), timeout);
}
if (param)
for (i = 0; i < receive; i++)
param[i] = ps2dev->cmdbuf[(receive - 1) - i];
if (ps2dev->cmdcnt && (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1))
goto out;
rc = 0;
out:
serio_pause_rx(ps2dev->serio);
ps2dev->flags = 0;
serio_continue_rx(ps2dev->serio);
mutex_unlock(&ps2dev->cmd_mutex);
return rc;
}
EXPORT_SYMBOL(ps2_command);
/*
* ps2_execute_scheduled_command() sends a command, previously scheduled by
* ps2_schedule_command(), to a PS/2 device (keyboard, mouse, etc.)
*/
static void ps2_execute_scheduled_command(struct work_struct *work)
{
struct ps2work *ps2work = container_of(work, struct ps2work, work);
ps2_command(ps2work->ps2dev, ps2work->param, ps2work->command);
kfree(ps2work);
}
/*
* ps2_schedule_command() allows to schedule delayed execution of a PS/2
* command and can be used to issue a command from an interrupt or softirq
* context.
*/
int ps2_schedule_command(struct ps2dev *ps2dev, unsigned char *param, int command)
{
struct ps2work *ps2work;
int send = (command >> 12) & 0xf;
int receive = (command >> 8) & 0xf;
if (!(ps2work = kmalloc(sizeof(struct ps2work) + max(send, receive), GFP_ATOMIC)))
return -1;
memset(ps2work, 0, sizeof(struct ps2work));
ps2work->ps2dev = ps2dev;
ps2work->command = command;
memcpy(ps2work->param, param, send);
INIT_WORK(&ps2work->work, ps2_execute_scheduled_command);
if (!schedule_work(&ps2work->work)) {
kfree(ps2work);
return -1;
}
return 0;
}
EXPORT_SYMBOL(ps2_schedule_command);
/*
* ps2_init() initializes ps2dev structure
*/
void ps2_init(struct ps2dev *ps2dev, struct serio *serio)
{
mutex_init(&ps2dev->cmd_mutex);
lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
init_waitqueue_head(&ps2dev->wait);
ps2dev->serio = serio;
}
EXPORT_SYMBOL(ps2_init);
/*
* ps2_handle_ack() is supposed to be used in interrupt handler
* to properly process ACK/NAK of a command from a PS/2 device.
*/
int ps2_handle_ack(struct ps2dev *ps2dev, unsigned char data)
{
switch (data) {
case PS2_RET_ACK:
ps2dev->nak = 0;
break;
case PS2_RET_NAK:
ps2dev->nak = 1;
break;
/*
* Workaround for mice which don't ACK the Get ID command.
* These are valid mouse IDs that we recognize.
*/
case 0x00:
case 0x03:
case 0x04:
if (ps2dev->flags & PS2_FLAG_WAITID) {
ps2dev->nak = 0;
break;
}
/* Fall through */
default:
return 0;
}
if (!ps2dev->nak && ps2dev->cmdcnt)
ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
ps2dev->flags &= ~PS2_FLAG_ACK;
wake_up(&ps2dev->wait);
if (data != PS2_RET_ACK)
ps2_handle_response(ps2dev, data);
return 1;
}
EXPORT_SYMBOL(ps2_handle_ack);
/*
* ps2_handle_response() is supposed to be used in interrupt handler
* to properly store device's response to a command and notify process
* waiting for completion of the command.
*/
int ps2_handle_response(struct ps2dev *ps2dev, unsigned char data)
{
if (ps2dev->cmdcnt)
ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
if (ps2dev->flags & PS2_FLAG_CMD1) {
ps2dev->flags &= ~PS2_FLAG_CMD1;
if (ps2dev->cmdcnt)
wake_up(&ps2dev->wait);
}
if (!ps2dev->cmdcnt) {
ps2dev->flags &= ~PS2_FLAG_CMD;
wake_up(&ps2dev->wait);
}
return 1;
}
EXPORT_SYMBOL(ps2_handle_response);
void ps2_cmd_aborted(struct ps2dev *ps2dev)
{
if (ps2dev->flags & PS2_FLAG_ACK)
ps2dev->nak = 1;
if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
wake_up(&ps2dev->wait);
ps2dev->flags = 0;
}
EXPORT_SYMBOL(ps2_cmd_aborted);