1 files changed, 494 insertions, 0 deletions
diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
new file mode 100644
index 000000000..3e19344ed
--- /dev/null
+++ b/drivers/input/serio/libps2.c
@@ -0,0 +1,494 @@
+// 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"
+
+MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
+MODULE_DESCRIPTION("PS/2 driver library");
+MODULE_LICENSE("GPL");
+
+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 waits for acknowledge.
+ * It 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);
+
+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);
+
+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.
+ */
+
+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.
+ */
+
+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() 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, 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->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];
+
+	/* Signal that we are sending the command byte */
+	ps2dev->flags |= PS2_FLAG_ACK_CMD;
+
+	/*
+	 * Some devices (Synaptics) peform 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;
+
+	/* Now we are sending command parameters, if any */
+	ps2dev->flags &= ~PS2_FLAG_ACK_CMD;
+
+	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);
+
+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 the mouse
+ * 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
+ */
+
+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.
+ */
+
+bool 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.
+		 * 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);
+		ps2dev->flags &= ~PS2_FLAG_WAITID;
+		return ps2dev->flags & PS2_FLAG_ACK_CMD;
+	}
+
+	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 true;
+}
+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.
+ */
+
+bool 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);
+	}
+
+	return true;
+}
+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);