linux/drivers/input/serio/libps2.c
Dmitry Torokhov a3ce6ea46c Input: libps2 - better handle bad scheduler decisions
Sometimes devices send us their responses in time but due to
unfortunate scheduling decisions the receiving thread does not
get scheduled till much later and we erroneously decide that
device timed out. Work around this problem by checking whether we
received the data we needed instead of checking timeout
condition.

Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2009-05-28 10:34:02 -07:00

346 lines
7.9 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/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");
/*
* 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)
{
static const 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 && !(ps2dev->flags & PS2_FLAG_CMD1)) {
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_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->flags |= PS2_FLAG_NAK;
ps2dev->nak = PS2_RET_NAK;
break;
case PS2_RET_ERR:
if (ps2dev->flags & PS2_FLAG_NAK) {
ps2dev->flags &= ~PS2_FLAG_NAK;
ps2dev->nak = PS2_RET_ERR;
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->flags &= ~PS2_FLAG_NAK;
if (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);
/* reset all flags except last nack */
ps2dev->flags &= PS2_FLAG_NAK;
}
EXPORT_SYMBOL(ps2_cmd_aborted);