Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / input / serio / libps2.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;

        guard(serio_pause_rx)(ps2dev->serio);

        retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
        dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);

        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);

        scoped_guard(serio_pause_rx, ps2dev->serio) {
                ps2dev->flags = PS2_FLAG_CMD;
                ps2dev->cmdcnt = maxbytes;
        }

        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) {
                        scoped_guard(serio_pause_rx, ps2dev->serio)
                                ps2dev->flags = 0;

                        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])) {
                        scoped_guard(serio_pause_rx, ps2dev->serio)
                                ps2dev->flags = ps2dev->cmdcnt = 0;

                        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);

        /*
         * Not using guard notation because we need to break critical
         * section below while waiting for the response.
         */
        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");