linux/drivers/input/serio/libps2.c
Dmitry Torokhov f219050af0 Input: libps2 - do not discard non-ack bytes when controlling LEDs
Upon receiving a PS/2 command the device and controller are supposed to
stop sending normal data (scancodes or movement packets) and instead
immediately start delivering ACK/NAK and command response. Unfortunately
often EC has an output buffer which may contain latched data by the time
the EC receives a command from the host. The kernel used to ignore such
data, but that may cause "stuck" keys if the data dropped happens to be a
break code or a part of a break code. This occasionally happens, for
example, on Chromebooks when the kernel tries to toggle CapsLock LED on
a keyboard while user releases Alt+Search keyboard shortcut.

Fix this by passing the first non-ACK byte to the normal handler for a
handful of PS/2 commands that are expected to be used during normal device
operation (as opposed to probe/configuration time).

Reviewed-by: Raul E Rangel <rrangel@chromium.org>
Link: https://lore.kernel.org/r/20230511185252.386941-8-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
2023-05-18 11:40:32 -07:00

624 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* PS/2 driver library
*
* Copyright (c) 1999-2002 Vojtech Pavlik
* Copyright (c) 2004 Dmitry Torokhov
*/
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/kmsan-checks.h>
#include <linux/serio.h>
#include <linux/i8042.h>
#include <linux/libps2.h>
#define DRIVER_DESC "PS/2 driver library"
#define PS2_CMD_SETSCALE11 0x00e6
#define PS2_CMD_SETRES 0x10e8
#define PS2_CMD_EX_SETLEDS 0x20eb
#define PS2_CMD_SETLEDS 0x10ed
#define PS2_CMD_GETID 0x02f2
#define PS2_CMD_SETREP 0x10f3 /* Set repeat rate/set report rate */
#define PS2_CMD_RESET_BAT 0x02ff
#define PS2_RET_BAT 0xaa
#define PS2_RET_ID 0x00
#define PS2_RET_ACK 0xfa
#define PS2_RET_NAK 0xfe
#define PS2_RET_ERR 0xfc
#define PS2_FLAG_ACK BIT(0) /* Waiting for ACK/NAK */
#define PS2_FLAG_CMD BIT(1) /* Waiting for a command to finish */
#define PS2_FLAG_CMD1 BIT(2) /* Waiting for the first byte of command response */
#define PS2_FLAG_WAITID BIT(3) /* Command executing is GET ID */
#define PS2_FLAG_NAK BIT(4) /* Last transmission was NAKed */
#define PS2_FLAG_PASS_NOACK BIT(5) /* Pass non-ACK byte to receive handler */
static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
unsigned int timeout, unsigned int max_attempts)
__releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
{
int attempt = 0;
int error;
lockdep_assert_held(&ps2dev->serio->lock);
do {
ps2dev->nak = 1;
ps2dev->flags |= PS2_FLAG_ACK;
serio_continue_rx(ps2dev->serio);
error = serio_write(ps2dev->serio, byte);
if (error)
dev_dbg(&ps2dev->serio->dev,
"failed to write %#02x: %d\n", byte, error);
else
wait_event_timeout(ps2dev->wait,
!(ps2dev->flags & PS2_FLAG_ACK),
msecs_to_jiffies(timeout));
serio_pause_rx(ps2dev->serio);
} while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);
ps2dev->flags &= ~PS2_FLAG_ACK;
if (!error) {
switch (ps2dev->nak) {
case 0:
break;
case PS2_RET_NAK:
error = -EAGAIN;
break;
case PS2_RET_ERR:
error = -EPROTO;
break;
default:
error = -EIO;
break;
}
}
if (error || attempt > 1)
dev_dbg(&ps2dev->serio->dev,
"%02x - %d (%x), attempt %d\n",
byte, error, ps2dev->nak, attempt);
return error;
}
/**
* ps2_sendbyte - sends a byte to the device and wait for acknowledgement
* @ps2dev: a PS/2 device to send the data to
* @byte: data to be sent to the device
* @timeout: timeout for sending the data and receiving an acknowledge
*
* The function doesn't handle retransmission, the caller is expected to handle
* it when needed.
*
* ps2_sendbyte() can only be called from a process context.
*/
int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
{
int retval;
serio_pause_rx(ps2dev->serio);
retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);
serio_continue_rx(ps2dev->serio);
return retval;
}
EXPORT_SYMBOL(ps2_sendbyte);
/**
* ps2_begin_command - mark beginning of execution of a complex command
* @ps2dev: a PS/2 device executing the command
*
* Serializes a complex/compound command. Once command is finished
* ps2_end_command() should be called.
*/
void ps2_begin_command(struct ps2dev *ps2dev)
{
struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
mutex_lock(m);
}
EXPORT_SYMBOL(ps2_begin_command);
/**
* ps2_end_command - mark end of execution of a complex command
* @ps2dev: a PS/2 device executing the command
*/
void ps2_end_command(struct ps2dev *ps2dev)
{
struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
mutex_unlock(m);
}
EXPORT_SYMBOL(ps2_end_command);
/**
* ps2_drain - waits for device to transmit requested number of bytes
* and discards them
* @ps2dev: the PS/2 device that should be drained
* @maxbytes: maximum number of bytes to be drained
* @timeout: time to drain the device
*/
void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout)
{
if (maxbytes > sizeof(ps2dev->cmdbuf)) {
WARN_ON(1);
maxbytes = sizeof(ps2dev->cmdbuf);
}
ps2_begin_command(ps2dev);
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));
ps2_end_command(ps2dev);
}
EXPORT_SYMBOL(ps2_drain);
/**
* ps2_is_keyboard_id - checks received ID byte against the list of
* known keyboard IDs
* @id_byte: data byte that should be checked
*/
bool ps2_is_keyboard_id(u8 id_byte)
{
static const u8 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,
unsigned int command, unsigned 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 - send a command to PS/2 device
* @ps2dev: the PS/2 device that should execute the command
* @param: a buffer containing parameters to be sent along with the command,
* or place where the results of the command execution will be deposited,
* or both
* @command: command word that encodes the command itself, as well as number of
* additional parameter bytes that should be sent to the device and expected
* length of the command response
*
* Not serialized. Callers should use ps2_begin_command() and ps2_end_command()
* to ensure proper serialization for complex commands.
*/
int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
{
unsigned int timeout;
unsigned int send = (command >> 12) & 0xf;
unsigned int receive = (command >> 8) & 0xf;
int rc;
int i;
u8 send_param[16];
if (receive > sizeof(ps2dev->cmdbuf)) {
WARN_ON(1);
return -EINVAL;
}
if (send && !param) {
WARN_ON(1);
return -EINVAL;
}
memcpy(send_param, param, send);
serio_pause_rx(ps2dev->serio);
ps2dev->cmdcnt = receive;
switch (command) {
case PS2_CMD_GETID:
/*
* Some mice do not ACK the "get ID" command, prepare to
* handle this.
*/
ps2dev->flags = PS2_FLAG_WAITID;
break;
case PS2_CMD_SETLEDS:
case PS2_CMD_EX_SETLEDS:
case PS2_CMD_SETREP:
ps2dev->flags = PS2_FLAG_PASS_NOACK;
break;
default:
ps2dev->flags = 0;
break;
}
if (receive) {
/* Indicate that we expect response to the command. */
ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
if (param)
for (i = 0; i < receive; i++)
ps2dev->cmdbuf[(receive - 1) - i] = param[i];
}
/*
* Some devices (Synaptics) perform the reset before
* ACKing the reset command, and so it can take a long
* time before the ACK arrives.
*/
timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
if (rc)
goto out_reset_flags;
/* Send command parameters, if any. */
for (i = 0; i < send; i++) {
rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
if (rc)
goto out_reset_flags;
}
serio_continue_rx(ps2dev->serio);
/*
* 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);
}
serio_pause_rx(ps2dev->serio);
if (param) {
for (i = 0; i < receive; i++)
param[i] = ps2dev->cmdbuf[(receive - 1) - i];
kmsan_unpoison_memory(param, receive);
}
if (ps2dev->cmdcnt &&
(command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
rc = -EPROTO;
goto out_reset_flags;
}
rc = 0;
out_reset_flags:
ps2dev->flags = 0;
serio_continue_rx(ps2dev->serio);
dev_dbg(&ps2dev->serio->dev,
"%02x [%*ph] - %x/%08lx [%*ph]\n",
command & 0xff, send, send_param,
ps2dev->nak, ps2dev->flags,
receive, param ?: send_param);
/*
* ps_command() handles resends itself, so do not leak -EAGAIN
* to the callers.
*/
return rc != -EAGAIN ? rc : -EPROTO;
}
EXPORT_SYMBOL(__ps2_command);
/**
* ps2_command - send a command to PS/2 device
* @ps2dev: the PS/2 device that should execute the command
* @param: a buffer containing parameters to be sent along with the command,
* or place where the results of the command execution will be deposited,
* or both
* @command: command word that encodes the command itself, as well as number of
* additional parameter bytes that should be sent to the device and expected
* length of the command response
*
* Note: ps2_command() serializes the command execution so that only one
* command can be executed at a time for either individual port or the entire
* 8042 controller.
*/
int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
{
int rc;
ps2_begin_command(ps2dev);
rc = __ps2_command(ps2dev, param, command);
ps2_end_command(ps2dev);
return rc;
}
EXPORT_SYMBOL(ps2_command);
/**
* ps2_sliced_command - sends an extended PS/2 command to a mouse
* @ps2dev: the PS/2 device that should execute the command
* @command: command byte
*
* The command is sent using "sliced" syntax understood by advanced devices,
* such as Logitech or Synaptics touchpads. The command is encoded as:
* 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
* is the command.
*/
int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
{
int i;
int retval;
ps2_begin_command(ps2dev);
retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
if (retval)
goto out;
for (i = 6; i >= 0; i -= 2) {
u8 d = (command >> i) & 3;
retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
if (retval)
break;
}
out:
dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
ps2_end_command(ps2dev);
return retval;
}
EXPORT_SYMBOL(ps2_sliced_command);
/**
* ps2_init - initializes ps2dev structure
* @ps2dev: structure to be initialized
* @serio: serio port associated with the PS/2 device
* @pre_receive_handler: validation handler to check basic communication state
* @receive_handler: main protocol handler
*
* Prepares ps2dev structure for use in drivers for PS/2 devices.
*/
void ps2_init(struct ps2dev *ps2dev, struct serio *serio,
ps2_pre_receive_handler_t pre_receive_handler,
ps2_receive_handler_t receive_handler)
{
ps2dev->pre_receive_handler = pre_receive_handler;
ps2dev->receive_handler = receive_handler;
mutex_init(&ps2dev->cmd_mutex);
lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
init_waitqueue_head(&ps2dev->wait);
ps2dev->serio = serio;
serio_set_drvdata(serio, ps2dev);
}
EXPORT_SYMBOL(ps2_init);
/*
* ps2_handle_response() stores device's response to a command and notifies
* the process waiting for completion of the command. Note that there is a
* distinction between waiting for the first byte of the response, and
* waiting for subsequent bytes. It is done so that callers could shorten
* timeouts once first byte of response is received.
*/
static void ps2_handle_response(struct ps2dev *ps2dev, u8 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);
}
}
/*
* ps2_handle_ack() processes ACK/NAK of a command from a PS/2 device,
* possibly applying workarounds for mice not acknowledging the "get ID"
* command.
*/
static void ps2_handle_ack(struct ps2dev *ps2dev, u8 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;
}
fallthrough;
/*
* 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;
}
fallthrough;
default:
/*
* Do not signal errors if we get unexpected reply while
* waiting for an ACK to the initial (first) command byte:
* the device might not be quiesced yet and continue
* delivering data. For certain commands (such as set leds and
* set repeat rate) that can be used during normal device
* operation, we even pass this data byte to the normal receive
* handler.
* Note that we reset PS2_FLAG_WAITID flag, so the workaround
* for mice not acknowledging the Get ID command only triggers
* on the 1st byte; if device spews data we really want to see
* a real ACK from it.
*/
dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
if (ps2dev->flags & PS2_FLAG_PASS_NOACK)
ps2dev->receive_handler(ps2dev, data);
ps2dev->flags &= ~(PS2_FLAG_WAITID | PS2_FLAG_PASS_NOACK);
return;
}
if (!ps2dev->nak)
ps2dev->flags &= ~PS2_FLAG_NAK;
ps2dev->flags &= ~PS2_FLAG_ACK;
if (!ps2dev->nak && data != PS2_RET_ACK)
ps2_handle_response(ps2dev, data);
else
wake_up(&ps2dev->wait);
}
/*
* Clears state of PS/2 device after communication error by resetting majority
* of flags and waking up waiters, if any.
*/
static void ps2_cleanup(struct ps2dev *ps2dev)
{
unsigned long old_flags = ps2dev->flags;
/* reset all flags except last nak */
ps2dev->flags &= PS2_FLAG_NAK;
if (old_flags & PS2_FLAG_ACK)
ps2dev->nak = 1;
if (old_flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
wake_up(&ps2dev->wait);
}
/**
* ps2_interrupt - common interrupt handler for PS/2 devices
* @serio: serio port for the device
* @data: a data byte received from the device
* @flags: flags such as %SERIO_PARITY or %SERIO_TIMEOUT indicating state of
* the data transfer
*
* ps2_interrupt() invokes pre-receive handler, optionally handles command
* acknowledgement and response from the device, and finally passes the data
* to the main protocol handler for future processing.
*/
irqreturn_t ps2_interrupt(struct serio *serio, u8 data, unsigned int flags) {
struct ps2dev *ps2dev = serio_get_drvdata(serio);
enum ps2_disposition rc;
rc = ps2dev->pre_receive_handler(ps2dev, data, flags);
switch (rc) {
case PS2_ERROR:
ps2_cleanup(ps2dev);
break;
case PS2_IGNORE:
break;
case PS2_PROCESS:
if (ps2dev->flags & PS2_FLAG_ACK)
ps2_handle_ack(ps2dev, data);
else if (ps2dev->flags & PS2_FLAG_CMD)
ps2_handle_response(ps2dev, data);
else
ps2dev->receive_handler(ps2dev, data);
break;
}
return IRQ_HANDLED;
}
EXPORT_SYMBOL(ps2_interrupt);
MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
MODULE_DESCRIPTION("PS/2 driver library");
MODULE_LICENSE("GPL");