input/serio/i8042.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  i8042 keyboard and mouse controller driver for Linux
 *
 *  Copyright (c) 1999-2004 Vojtech Pavlik
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/err.h>
#include <linux/rcupdate.h>
#include <linux/platform_device.h>
#include <linux/i8042.h>
#include <linux/slab.h>
#include <linux/suspend.h>
#include <linux/property.h>

#include <asm/io.h>

MODULE_AUTHOR("Vojtech Pavlik <[email protected]>");
MODULE_DESCRIPTION("i8042 keyboard and mouse controller driver");
MODULE_LICENSE("GPL");

static bool i8042_nokbd;
module_param_named(nokbd, i8042_nokbd, bool, 0);
MODULE_PARM_DESC(nokbd, "Do not probe or use KBD port.");

static bool i8042_noaux;
module_param_named(noaux, i8042_noaux, bool, 0);
MODULE_PARM_DESC(noaux, "Do not probe or use AUX (mouse) port.");

static bool i8042_nomux;
module_param_named(nomux, i8042_nomux, bool, 0);
MODULE_PARM_DESC(nomux, "Do not check whether an active multiplexing controller is present.");

static bool i8042_unlock;
module_param_named(unlock, i8042_unlock, bool, 0);
MODULE_PARM_DESC(unlock, "Ignore keyboard lock.");

static bool i8042_probe_defer;
module_param_named(probe_defer, i8042_probe_defer, bool, 0);
MODULE_PARM_DESC(probe_defer, "Allow deferred probing.");

enum i8042_controller_reset_mode {
	I8042_RESET_NEVER,
	I8042_RESET_ALWAYS,
	I8042_RESET_ON_S2RAM,
#define I8042_RESET_DEFAULT	I8042_RESET_ON_S2RAM
};
static enum i8042_controller_reset_mode i8042_reset = I8042_RESET_DEFAULT;
static int i8042_set_reset(const char *val, const struct kernel_param *kp)
{
	enum i8042_controller_reset_mode *arg = kp->arg;
	int error;
	bool reset;

	if (val) {
		error = kstrtobool(val, &reset);
		if (error)
			return error;
	} else {
		reset = true;
	}

	*arg = reset ? I8042_RESET_ALWAYS : I8042_RESET_NEVER;
	return 0;
}

static const struct kernel_param_ops param_ops_reset_param = {
	.flags = KERNEL_PARAM_OPS_FL_NOARG,
	.set = i8042_set_reset,
};
#define param_check_reset_param(name, p)	\
	__param_check(name, p, enum i8042_controller_reset_mode)
module_param_named(reset, i8042_reset, reset_param, 0);
MODULE_PARM_DESC(reset, "Reset controller on resume, cleanup or both");

static bool i8042_direct;
module_param_named(direct, i8042_direct, bool, 0);
MODULE_PARM_DESC(direct, "Put keyboard port into non-translated mode.");

static bool i8042_dumbkbd;
module_param_named(dumbkbd, i8042_dumbkbd, bool, 0);
MODULE_PARM_DESC(dumbkbd, "Pretend that controller can only read data from keyboard");

static bool i8042_noloop;
module_param_named(noloop, i8042_noloop, bool, 0);
MODULE_PARM_DESC(noloop, "Disable the AUX Loopback command while probing for the AUX port");

static bool i8042_notimeout;
module_param_named(notimeout, i8042_notimeout, bool, 0);
MODULE_PARM_DESC(notimeout, "Ignore timeouts signalled by i8042");

static bool i8042_kbdreset;
module_param_named(kbdreset, i8042_kbdreset, bool, 0);
MODULE_PARM_DESC(kbdreset, "Reset device connected to KBD port");

#ifdef CONFIG_X86
static bool i8042_dritek;
module_param_named(dritek, i8042_dritek, bool, 0);
MODULE_PARM_DESC(dritek, "Force enable the Dritek keyboard extension");
#endif

#ifdef CONFIG_PNP
static bool i8042_nopnp;
module_param_named(nopnp, i8042_nopnp, bool, 0);
MODULE_PARM_DESC(nopnp, "Do not use PNP to detect controller settings");
#endif

static bool i8042_forcenorestore;
module_param_named(forcenorestore, i8042_forcenorestore, bool, 0);
MODULE_PARM_DESC(forcenorestore, "Force no restore on s3 resume, copying s2idle behaviour");

#define DEBUG
#ifdef DEBUG
static bool i8042_debug;
module_param_named(debug, i8042_debug, bool, 0600);
MODULE_PARM_DESC(debug, "Turn i8042 debugging mode on and off");

static bool i8042_unmask_kbd_data;
module_param_named(unmask_kbd_data, i8042_unmask_kbd_data, bool, 0600);
MODULE_PARM_DESC(unmask_kbd_data, "Unconditional enable (may reveal sensitive data) of normally sanitize-filtered kbd data traffic debug log [pre-condition: i8042.debug=1 enabled]");
#endif

static bool i8042_present;
static bool i8042_bypass_aux_irq_test;
static char i8042_kbd_firmware_id[128];
static char i8042_aux_firmware_id[128];
static struct fwnode_handle *i8042_kbd_fwnode;

#include "i8042.h"

/*
 * i8042_lock protects serialization between i8042_command and
 * the interrupt handler.
 */
static DEFINE_SPINLOCK(i8042_lock);

/*
 * Writers to AUX and KBD ports as well as users issuing i8042_command
 * directly should acquire i8042_mutex (by means of calling
 * i8042_lock_chip() and i8042_unlock_chip() helpers) to ensure that
 * they do not disturb each other (unfortunately in many i8042
 * implementations write to one of the ports will immediately abort
 * command that is being processed by another port).
 */
static DEFINE_MUTEX(i8042_mutex);

struct i8042_port {
	struct serio *serio;
	int irq;
	bool exists;
	bool driver_bound;
	signed char mux;
};

#define I8042_KBD_PORT_NO	0
#define I8042_AUX_PORT_NO	1
#define I8042_MUX_PORT_NO	2
#define I8042_NUM_PORTS		(I8042_NUM_MUX_PORTS + 2)

static struct i8042_port i8042_ports[I8042_NUM_PORTS];

static unsigned char i8042_initial_ctr;
static unsigned char i8042_ctr;
static bool i8042_mux_present;
static bool i8042_kbd_irq_registered;
static bool i8042_aux_irq_registered;
static unsigned char i8042_suppress_kbd_ack;
static struct platform_device *i8042_platform_device;
static struct notifier_block i8042_kbd_bind_notifier_block;

static bool i8042_handle_data(int irq);
static i8042_filter_t i8042_platform_filter;
static void *i8042_platform_filter_context;

void i8042_lock_chip(void)
{
	mutex_lock(&i8042_mutex);
}
EXPORT_SYMBOL(i8042_lock_chip);

void i8042_unlock_chip(void)
{
	mutex_unlock(&i8042_mutex);
}
EXPORT_SYMBOL(i8042_unlock_chip);

int i8042_install_filter(i8042_filter_t filter, void *context)
{
	guard(spinlock_irqsave)(&i8042_lock);

	if (i8042_platform_filter)
		return -EBUSY;

	i8042_platform_filter = filter;
	i8042_platform_filter_context = context;
	return 0;
}
EXPORT_SYMBOL(i8042_install_filter);

int i8042_remove_filter(i8042_filter_t filter)
{
	guard(spinlock_irqsave)(&i8042_lock);

	if (i8042_platform_filter != filter)
		return -EINVAL;

	i8042_platform_filter = NULL;
	i8042_platform_filter_context = NULL;
	return 0;
}
EXPORT_SYMBOL(i8042_remove_filter);

/*
 * The i8042_wait_read() and i8042_wait_write functions wait for the i8042 to
 * be ready for reading values from it / writing values to it.
 * Called always with i8042_lock held.
 */

static int i8042_wait_read(void)
{
	int i = 0;

	while ((~i8042_read_status() & I8042_STR_OBF) && (i < I8042_CTL_TIMEOUT)) {
		udelay(50);
		i++;
	}
	return -(i == I8042_CTL_TIMEOUT);
}

static int i8042_wait_write(void)
{
	int i = 0;

	while ((i8042_read_status() & I8042_STR_IBF) && (i < I8042_CTL_TIMEOUT)) {
		udelay(50);
		i++;
	}
	return -(i == I8042_CTL_TIMEOUT);
}

/*
 * i8042_flush() flushes all data that may be in the keyboard and mouse buffers
 * of the i8042 down the toilet.
 */

static int i8042_flush(void)
{
	unsigned char data, str;
	int count = 0;

	guard(spinlock_irqsave)(&i8042_lock);

	while ((str = i8042_read_status()) & I8042_STR_OBF) {
		if (count++ >= I8042_BUFFER_SIZE)
			return -EIO;

		udelay(50);
		data = i8042_read_data();
		dbg("%02x <- i8042 (flush, %s)\n",
		    data, str & I8042_STR_AUXDATA ? "aux" : "kbd");
	}

	return 0;
}

/*
 * i8042_command() executes a command on the i8042. It also sends the input
 * parameter(s) of the commands to it, and receives the output value(s). The
 * parameters are to be stored in the param array, and the output is placed
 * into the same array. The number of the parameters and output values is
 * encoded in bits 8-11 of the command number.
 */

static int __i8042_command(unsigned char *param, int command)
{
	int i, error;

	if (i8042_noloop && command == I8042_CMD_AUX_LOOP)
		return -1;

	error = i8042_wait_write();
	if (error)
		return error;

	dbg("%02x -> i8042 (command)\n", command & 0xff);
	i8042_write_command(command & 0xff);

	for (i = 0; i < ((command >> 12) & 0xf); i++) {
		error = i8042_wait_write();
		if (error) {
			dbg("     -- i8042 (wait write timeout)\n");
			return error;
		}
		dbg("%02x -> i8042 (parameter)\n", param[i]);
		i8042_write_data(param[i]);
	}

	for (i = 0; i < ((command >> 8) & 0xf); i++) {
		error = i8042_wait_read();
		if (error) {
			dbg("     -- i8042 (wait read timeout)\n");
			return error;
		}

		if (command == I8042_CMD_AUX_LOOP &&
		    !(i8042_read_status() & I8042_STR_AUXDATA)) {
			dbg("     -- i8042 (auxerr)\n");
			return -1;
		}

		param[i] = i8042_read_data();
		dbg("%02x <- i8042 (return)\n", param[i]);
	}

	return 0;
}

int i8042_command(unsigned char *param, int command)
{
	if (!i8042_present)
		return -1;

	guard(spinlock_irqsave)(&i8042_lock);

	return __i8042_command(param, command);
}
EXPORT_SYMBOL(i8042_command);

/*
 * i8042_kbd_write() sends a byte out through the keyboard interface.
 */

static int i8042_kbd_write(struct serio *port, unsigned char c)
{
	int error;

	guard(spinlock_irqsave)(&i8042_lock);

	error = i8042_wait_write();
	if (error)
		return error;

	dbg("%02x -> i8042 (kbd-data)\n", c);
	i8042_write_data(c);

	return 0;
}

/*
 * i8042_aux_write() sends a byte out through the aux interface.
 */

static int i8042_aux_write(struct serio *serio, unsigned char c)
{
	struct i8042_port *port = serio->port_data;

	return i8042_command(&c, port->mux == -1 ?
					I8042_CMD_AUX_SEND :
					I8042_CMD_MUX_SEND + port->mux);
}


/*
 * i8042_port_close attempts to clear AUX or KBD port state by disabling
 * and then re-enabling it.
 */

static void i8042_port_close(struct serio *serio)
{
	int irq_bit;
	int disable_bit;
	const char *port_name;

	if (serio == i8042_ports[I8042_AUX_PORT_NO].serio) {
		irq_bit = I8042_CTR_AUXINT;
		disable_bit = I8042_CTR_AUXDIS;
		port_name = "AUX";
	} else {
		irq_bit = I8042_CTR_KBDINT;
		disable_bit = I8042_CTR_KBDDIS;
		port_name = "KBD";
	}

	i8042_ctr &= ~irq_bit;
	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
		pr_warn("Can't write CTR while closing %s port\n", port_name);

	udelay(50);

	i8042_ctr &= ~disable_bit;
	i8042_ctr |= irq_bit;
	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
		pr_err("Can't reactivate %s port\n", port_name);

	/*
	 * See if there is any data appeared while we were messing with
	 * port state.
	 */
	i8042_handle_data(0);
}

/*
 * i8042_start() is called by serio core when port is about to finish
 * registering. It will mark port as existing so i8042_interrupt can
 * start sending data through it.
 */
static int i8042_start(struct serio *serio)
{
	struct i8042_port *port = serio->port_data;

	device_set_wakeup_capable(&serio->dev, true);

	/*
	 * On platforms using suspend-to-idle, allow the keyboard to
	 * wake up the system from sleep by enabling keyboard wakeups
	 * by default.  This is consistent with keyboard wakeup
	 * behavior on many platforms using suspend-to-RAM (ACPI S3)
	 * by default.
	 */
	if (pm_suspend_default_s2idle() &&
	    serio == i8042_ports[I8042_KBD_PORT_NO].serio) {
		device_set_wakeup_enable(&serio->dev, true);
	}

	guard(spinlock_irq)(&i8042_lock);
	port->exists = true;

	return 0;
}

/*
 * i8042_stop() marks serio port as non-existing so i8042_interrupt
 * will not try to send data to the port that is about to go away.
 * The function is called by serio core as part of unregister procedure.
 */
static void i8042_stop(struct serio *serio)
{
	struct i8042_port *port = serio->port_data;

	scoped_guard(spinlock_irq, &i8042_lock) {
		port->exists = false;
		port->serio = NULL;
	}

	/*
	 * We need to make sure that interrupt handler finishes using
	 * our serio port before we return from this function.
	 * We synchronize with both AUX and KBD IRQs because there is
	 * a (very unlikely) chance that AUX IRQ is raised for KBD port
	 * and vice versa.
	 */
	synchronize_irq(I8042_AUX_IRQ);
	synchronize_irq(I8042_KBD_IRQ);
}

/*
 * i8042_filter() filters out unwanted bytes from the input data stream.
 * It is called from i8042_interrupt and thus is running with interrupts
 * off and i8042_lock held.
 */
static bool i8042_filter(unsigned char data, unsigned char str,
			 struct serio *serio)
{
	if (unlikely(i8042_suppress_kbd_ack)) {
		if ((~str & I8042_STR_AUXDATA) &&
		    (data == 0xfa || data == 0xfe)) {
			i8042_suppress_kbd_ack--;
			dbg("Extra keyboard ACK - filtered out\n");
			return true;
		}
	}

	if (!i8042_platform_filter)
		return false;

	if (i8042_platform_filter(data, str, serio, i8042_platform_filter_context)) {
		dbg("Filtered out by platform filter\n");
		return true;
	}

	return false;
}

/*
 * i8042_handle_mux() handles case when data is coming from one of
 * the multiplexed ports. It would be simple if not for quirks with
 * handling errors:
 *
 * When MUXERR condition is signalled the data register can only contain
 * 0xfd, 0xfe or 0xff if implementation follows the spec. Unfortunately
 * it is not always the case. Some KBCs also report 0xfc when there is
 * nothing connected to the port while others sometimes get confused which
 * port the data came from and signal error leaving the data intact. They
 * _do not_ revert to legacy mode (actually I've never seen KBC reverting
 * to legacy mode yet, when we see one we'll add proper handling).
 * Anyway, we process 0xfc, 0xfd, 0xfe and 0xff as timeouts, and for the
 * rest assume that the data came from the same serio last byte
 * was transmitted (if transmission happened not too long ago).
 */
static int i8042_handle_mux(u8 str, u8 *data, unsigned int *dfl)
{
	static unsigned long last_transmit;
	static unsigned long last_port;
	unsigned int mux_port;

	mux_port = (str >> 6) & 3;
	*dfl = 0;

	if (str & I8042_STR_MUXERR) {
		dbg("MUX error, status is %02x, data is %02x\n",
		    str, *data);

		switch (*data) {
		default:
			if (time_before(jiffies, last_transmit + HZ/10)) {
				mux_port = last_port;
				break;
			}
			fallthrough;	/* report timeout */
		case 0xfc:
		case 0xfd:
		case 0xfe:
			*dfl = SERIO_TIMEOUT;
			*data = 0xfe;
			break;
		case 0xff:
			*dfl = SERIO_PARITY;
			*data = 0xfe;
			break;
		}
	}

	last_port = mux_port;
	last_transmit = jiffies;

	return I8042_MUX_PORT_NO + mux_port;
}

/*
 * i8042_handle_data() is the most important function in this driver -
 * it reads the data from the i8042, determines its destination serio
 * port, and sends received byte to the upper layers.
 *
 * Returns true if there was data waiting, false otherwise.
 */
static bool i8042_handle_data(int irq)
{
	struct i8042_port *port;
	struct serio *serio;
	unsigned char str, data;
	unsigned int dfl;
	unsigned int port_no;
	bool filtered;

	scoped_guard(spinlock_irqsave, &i8042_lock) {
		str = i8042_read_status();
		if (unlikely(~str & I8042_STR_OBF))
			return false;

		data = i8042_read_data();

		if (i8042_mux_present && (str & I8042_STR_AUXDATA)) {
			port_no = i8042_handle_mux(str, &data, &dfl);
		} else {

			dfl = (str & I8042_STR_PARITY) ? SERIO_PARITY : 0;
			if ((str & I8042_STR_TIMEOUT) && !i8042_notimeout)
				dfl |= SERIO_TIMEOUT;

			port_no = (str & I8042_STR_AUXDATA) ?
					I8042_AUX_PORT_NO : I8042_KBD_PORT_NO;
		}

		port = &i8042_ports[port_no];
		serio = port->exists ? port->serio : NULL;

		filter_dbg(port->driver_bound,
			   data, "<- i8042 (interrupt, %d, %d%s%s)\n",
			   port_no, irq,
			   dfl & SERIO_PARITY ? ", bad parity" : "",
			   dfl & SERIO_TIMEOUT ? ", timeout" : "");

		filtered = i8042_filter(data, str, serio);
	}

	if (likely(serio && !filtered))
		serio_interrupt(serio, data, dfl);

	return true;
}

static irqreturn_t i8042_interrupt(int irq, void *dev_id)
{
	if (unlikely(!i8042_handle_data(irq))) {
		dbg("Interrupt %d, without any data\n", irq);
		return IRQ_NONE;
	}

	return IRQ_HANDLED;
}

/*
 * i8042_enable_kbd_port enables keyboard port on chip
 */

static int i8042_enable_kbd_port(void)
{
	i8042_ctr &= ~I8042_CTR_KBDDIS;
	i8042_ctr |= I8042_CTR_KBDINT;

	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) {
		i8042_ctr &= ~I8042_CTR_KBDINT;
		i8042_ctr |= I8042_CTR_KBDDIS;
		pr_err("Failed to enable KBD port\n");
		return -EIO;
	}

	return 0;
}

/*
 * i8042_enable_aux_port enables AUX (mouse) port on chip
 */

static int i8042_enable_aux_port(void)
{
	i8042_ctr &= ~I8042_CTR_AUXDIS;
	i8042_ctr |= I8042_CTR_AUXINT;

	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) {
		i8042_ctr &= ~I8042_CTR_AUXINT;
		i8042_ctr |= I8042_CTR_AUXDIS;
		pr_err("Failed to enable AUX port\n");
		return -EIO;
	}

	return 0;
}

/*
 * i8042_enable_mux_ports enables 4 individual AUX ports after
 * the controller has been switched into Multiplexed mode
 */

static int i8042_enable_mux_ports(void)
{
	unsigned char param;
	int i;

	for (i = 0; i < I8042_NUM_MUX_PORTS; i++) {
		i8042_command(&param, I8042_CMD_MUX_PFX + i);
		i8042_command(&param, I8042_CMD_AUX_ENABLE);
	}

	return i8042_enable_aux_port();
}

/*
 * i8042_set_mux_mode checks whether the controller has an
 * active multiplexor and puts the chip into Multiplexed (true)
 * or Legacy (false) mode.
 */

static int i8042_set_mux_mode(bool multiplex, unsigned char *mux_version)
{

	unsigned char param, val;
/*
 * Get rid of bytes in the queue.
 */

	i8042_flush();

/*
 * Internal loopback test - send three bytes, they should come back from the
 * mouse interface, the last should be version.
 */

	param = val = 0xf0;
	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != val)
		return -1;
	param = val = multiplex ? 0x56 : 0xf6;
	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != val)
		return -1;
	param = val = multiplex ? 0xa4 : 0xa5;
	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param == val)
		return -1;

/*
 * Workaround for interference with USB Legacy emulation
 * that causes a v10.12 MUX to be found.
 */
	if (param == 0xac)
		return -1;

	if (mux_version)
		*mux_version = param;

	return 0;
}

/*
 * i8042_check_mux() checks whether the controller supports the PS/2 Active
 * Multiplexing specification by Synaptics, Phoenix, Insyde and
 * LCS/Telegraphics.
 */

static int i8042_check_mux(void)
{
	unsigned char mux_version;

	if (i8042_set_mux_mode(true, &mux_version))
		return -1;

	pr_info("Detected active multiplexing controller, rev %d.%d\n",
		(mux_version >> 4) & 0xf, mux_version & 0xf);

/*
 * Disable all muxed ports by disabling AUX.
 */
	i8042_ctr |= I8042_CTR_AUXDIS;
	i8042_ctr &= ~I8042_CTR_AUXINT;

	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) {
		pr_err("Failed to disable AUX port, can't use MUX\n");
		return -EIO;
	}

	i8042_mux_present = true;

	return 0;
}

/*
 * The following is used to test AUX IRQ delivery.
 */
static struct completion i8042_aux_irq_delivered;
static bool i8042_irq_being_tested;

static irqreturn_t i8042_aux_test_irq(int irq, void *dev_id)
{
	unsigned char str, data;

	guard(spinlock_irqsave)(&i8042_lock);

	str = i8042_read_status();
	if (!(str & I8042_STR_OBF))
		return IRQ_NONE;

	data = i8042_read_data();
	dbg("%02x <- i8042 (aux_test_irq, %s)\n",
	    data, str & I8042_STR_AUXDATA ? "aux" : "kbd");

	if (i8042_irq_being_tested && data == 0xa5 && (str & I8042_STR_AUXDATA))
		complete(&i8042_aux_irq_delivered);

	return IRQ_HANDLED;
}

/*
 * i8042_toggle_aux - enables or disables AUX port on i8042 via command and
 * verifies success by readinng CTR. Used when testing for presence of AUX
 * port.
 */
static int i8042_toggle_aux(bool on)
{
	unsigned char param;
	int i;

	if (i8042_command(&param,
			on ? I8042_CMD_AUX_ENABLE : I8042_CMD_AUX_DISABLE))
		return -1;

	/* some chips need some time to set the I8042_CTR_AUXDIS bit */
	for (i = 0; i < 100; i++) {
		udelay(50);

		if (i8042_command(&param, I8042_CMD_CTL_RCTR))
			return -1;

		if (!(param & I8042_CTR_AUXDIS) == on)
			return 0;
	}

	return -1;
}

/*
 * i8042_check_aux() applies as much paranoia as it can at detecting
 * the presence of an AUX interface.
 */

static int i8042_check_aux(void)
{
	int retval = -1;
	bool irq_registered = false;
	bool aux_loop_broken = false;
	unsigned char param;

/*
 * Get rid of bytes in the queue.
 */

	i8042_flush();

/*
 * Internal loopback test - filters out AT-type i8042's. Unfortunately
 * SiS screwed up and their 5597 doesn't support the LOOP command even
 * though it has an AUX port.
 */

	param = 0x5a;
	retval = i8042_command(&param, I8042_CMD_AUX_LOOP);
	if (retval || param != 0x5a) {

/*
 * External connection test - filters out AT-soldered PS/2 i8042's
 * 0x00 - no error, 0x01-0x03 - clock/data stuck, 0xff - general error
 * 0xfa - no error on some notebooks which ignore the spec
 * Because it's common for chipsets to return error on perfectly functioning
 * AUX ports, we test for this only when the LOOP command failed.
 */

		if (i8042_command(&param, I8042_CMD_AUX_TEST) ||
		    (param && param != 0xfa && param != 0xff))
			return -1;

/*
 * If AUX_LOOP completed without error but returned unexpected data
 * mark it as broken
 */
		if (!retval)
			aux_loop_broken = true;
	}

/*
 * Bit assignment test - filters out PS/2 i8042's in AT mode
 */

	if (i8042_toggle_aux(false)) {
		pr_warn("Failed to disable AUX port, but continuing anyway... Is this a SiS?\n");
		pr_warn("If AUX port is really absent please use the 'i8042.noaux' option\n");
	}

	if (i8042_toggle_aux(true))
		return -1;

/*
 * Reset keyboard (needed on some laptops to successfully detect
 * touchpad, e.g., some Gigabyte laptop models with Elantech
 * touchpads).
 */
	if (i8042_kbdreset) {
		pr_warn("Attempting to reset device connected to KBD port\n");
		i8042_kbd_write(NULL, (unsigned char) 0xff);
	}

/*
 * Test AUX IRQ delivery to make sure BIOS did not grab the IRQ and
 * used it for a PCI card or somethig else.
 */

	if (i8042_noloop || i8042_bypass_aux_irq_test || aux_loop_broken) {
/*
 * Without LOOP command we can't test AUX IRQ delivery. Assume the port
 * is working and hope we are right.
 */
		retval = 0;
		goto out;
	}

	if (request_irq(I8042_AUX_IRQ, i8042_aux_test_irq, IRQF_SHARED,
			"i8042", i8042_platform_device))
		goto out;

	irq_registered = true;

	if (i8042_enable_aux_port())
		goto out;

	scoped_guard(spinlock_irqsave, &i8042_lock) {
		init_completion(&i8042_aux_irq_delivered);
		i8042_irq_being_tested = true;

		param = 0xa5;
		retval = __i8042_command(&param, I8042_CMD_AUX_LOOP & 0xf0ff);
		if (retval)
			goto out;
	}

	if (wait_for_completion_timeout(&i8042_aux_irq_delivered,
					msecs_to_jiffies(250)) == 0) {
/*
 * AUX IRQ was never delivered so we need to flush the controller to
 * get rid of the byte we put there; otherwise keyboard may not work.
 */
		dbg("     -- i8042 (aux irq test timeout)\n");
		i8042_flush();
		retval = -1;
	}

 out:

/*
 * Disable the interface.
 */

	i8042_ctr |= I8042_CTR_AUXDIS;
	i8042_ctr &= ~I8042_CTR_AUXINT;

	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
		retval = -1;

	if (irq_registered)
		free_irq(I8042_AUX_IRQ, i8042_platform_device);

	return retval;
}

static int i8042_controller_check(void)
{
	if (i8042_flush()) {
		pr_info("No controller found\n");
		return -ENODEV;
	}

	return 0;
}

static int i8042_controller_selftest(void)
{
	unsigned char param;
	int i = 0;

	/*
	 * We try this 5 times; on some really fragile systems this does not
	 * take the first time...
	 */
	do {

		if (i8042_command(&param, I8042_CMD_CTL_TEST)) {
			pr_err("i8042 controller selftest timeout\n");
			return -ENODEV;
		}

		if (param == I8042_RET_CTL_TEST)
			return 0;

		dbg("i8042 controller selftest: %#x != %#x\n",
		    param, I8042_RET_CTL_TEST);
		msleep(50);
	} while (i++ < 5);

#ifdef CONFIG_X86
	/*
	 * On x86, we don't fail entire i8042 initialization if controller
	 * reset fails in hopes that keyboard port will still be functional
	 * and user will still get a working keyboard. This is especially
	 * important on netbooks. On other arches we trust hardware more.
	 */
	pr_info("giving up on controller selftest, continuing anyway...\n");
	return 0;
#else
	pr_err("i8042 controller selftest failed\n");
	return -EIO;
#endif
}

/*
 * i8042_controller_init initializes the i8042 controller, and,
 * most importantly, sets it into non-xlated mode if that's
 * desired.
 */

static int i8042_controller_init(void)
{
	int n = 0;
	unsigned char ctr[2];

/*
 * Save the CTR for restore on unload / reboot.
 */

	do {
		if (n >= 10) {
			pr_err("Unable to get stable CTR read\n");
			return -EIO;
		}

		if (n != 0)
			udelay(50);

		if (i8042_command(&ctr[n++ % 2], I8042_CMD_CTL_RCTR)) {
			pr_err("Can't read CTR while initializing i8042\n");
			return i8042_probe_defer ? -EPROBE_DEFER : -EIO;
		}

	} while (n < 2 || ctr[0] != ctr[1]);

	i8042_initial_ctr = i8042_ctr = ctr[0];

/*
 * Disable the keyboard interface and interrupt.
 */

	i8042_ctr |= I8042_CTR_KBDDIS;
	i8042_ctr &= ~I8042_CTR_KBDINT;

/*
 * Handle keylock.
 */

	scoped_guard(spinlock_irqsave, &i8042_lock) {
		if (~i8042_read_status() & I8042_STR_KEYLOCK) {
			if (i8042_unlock)
				i8042_ctr |= I8042_CTR_IGNKEYLOCK;
			else
				pr_warn("Warning: Keylock active\n");
		}
	}

/*
 * If the chip is configured into nontranslated mode by the BIOS, don't
 * bother enabling translating and be happy.
 */

	if (~i8042_ctr & I8042_CTR_XLATE)
		i8042_direct = true;

/*
 * Set nontranslated mode for the kbd interface if requested by an option.
 * After this the kbd interface becomes a simple serial in/out, like the aux
 * interface is. We don't do this by default, since it can confuse notebook
 * BIOSes.
 */

	if (i8042_direct)
		i8042_ctr &= ~I8042_CTR_XLATE;

/*
 * Write CTR back.
 */

	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) {
		pr_err("Can't write CTR while initializing i8042\n");
		return -EIO;
	}

/*
 * Flush whatever accumulated while we were disabling keyboard port.
 */

	i8042_flush();

	return 0;
}


/*
 * Reset the controller and reset CRT to the original value set by BIOS.
 */

static void i8042_controller_reset(bool s2r_wants_reset)
{
	i8042_flush();

/*
 * Disable both KBD and AUX interfaces so they don't get in the way
 */

	i8042_ctr |= I8042_CTR_KBDDIS | I8042_CTR_AUXDIS;
	i8042_ctr &= ~(I8042_CTR_KBDINT | I8042_CTR_AUXINT);

	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
		pr_warn("Can't write CTR while resetting\n");

/*
 * Disable MUX mode if present.
 */

	if (i8042_mux_present)
		i8042_set_mux_mode(false, NULL);

/*
 * Reset the controller if requested.
 */

	if (i8042_reset == I8042_RESET_ALWAYS ||
	    (i8042_reset == I8042_RESET_ON_S2RAM && s2r_wants_reset)) {
		i8042_controller_selftest();
	}

/*
 * Restore the original control register setting.
 */

	if (i8042_command(&i8042_initial_ctr, I8042_CMD_CTL_WCTR))
		pr_warn("Can't restore CTR\n");
}


/*
 * i8042_panic_blink() will turn the keyboard LEDs on or off and is called
 * when kernel panics. Flashing LEDs is useful for users running X who may
 * not see the console and will help distinguishing panics from "real"
 * lockups.
 *
 * Note that DELAY has a limit of 10ms so we will not get stuck here
 * waiting for KBC to free up even if KBD interrupt is off
 */

#define DELAY do { mdelay(1); if (++delay > 10) return delay; } while(0)

static long i8042_panic_blink(int state)
{
	long delay = 0;
	char led;

	led = (state) ? 0x01 | 0x04 : 0;
	while (i8042_read_status() & I8042_STR_IBF)
		DELAY;
	dbg("%02x -> i8042 (panic blink)\n", 0xed);
	i8042_suppress_kbd_ack = 2;
	i8042_write_data(0xed); /* set leds */
	DELAY;
	while (i8042_read_status() & I8042_STR_IBF)
		DELAY;
	DELAY;
	dbg("%02x -> i8042 (panic blink)\n", led);
	i8042_write_data(led);
	DELAY;
	return delay;
}

#undef DELAY

#ifdef CONFIG_X86
static void i8042_dritek_enable(void)
{
	unsigned char param = 0x90;
	int error;

	error = i8042_command(&param, 0x1059);
	if (error)
		pr_warn("Failed to enable DRITEK extension: %d\n", error);
}
#endif

#ifdef CONFIG_PM

/*
 * Here we try to reset everything back to a state we had
 * before suspending.
 */

static int i8042_controller_resume(bool s2r_wants_reset)
{
	int error;

	error = i8042_controller_check();
	if (error)
		return error;

	if (i8042_reset == I8042_RESET_ALWAYS ||
	    (i8042_reset == I8042_RESET_ON_S2RAM && s2r_wants_reset)) {
		error = i8042_controller_selftest();
		if (error)
			return error;
	}

/*
 * Restore original CTR value and disable all ports
 */

	i8042_ctr = i8042_initial_ctr;
	if (i8042_direct)
		i8042_ctr &= ~I8042_CTR_XLATE;
	i8042_ctr |= I8042_CTR_AUXDIS | I8042_CTR_KBDDIS;
	i8042_ctr &= ~(I8042_CTR_AUXINT | I8042_CTR_KBDINT);
	if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) {
		pr_warn("Can't write CTR to resume, retrying...\n");
		msleep(50);
		if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) {
			pr_err("CTR write retry failed\n");
			return -EIO;
		}
	}


#ifdef CONFIG_X86
	if (i8042_dritek)
		i8042_dritek_enable();
#endif

	if (i8042_mux_present) {
		if (i8042_set_mux_mode(true, NULL) || i8042_enable_mux_ports())
			pr_warn("failed to resume active multiplexor, mouse won't work\n");
	} else if (i8042_ports[I8042_AUX_PORT_NO].serio) {
		i8042_enable_aux_port();
	}

	if (i8042_ports[I8042_KBD_PORT_NO].serio)
		i8042_enable_kbd_port();

	i8042_handle_data(0);

	return 0;
}

/*
 * Here we try to restore the original BIOS settings to avoid
 * upsetting it.
 */

static int i8042_pm_suspend(struct device *dev)
{
	int i;

	if (!i8042_forcenorestore && pm_suspend_via_firmware())
		i8042_controller_reset(true);

	/* Set up serio interrupts for system wakeup. */
	for (i = 0; i < I8042_NUM_PORTS; i++) {
		struct serio *serio = i8042_ports[i].serio;

		if (serio && device_may_wakeup(&serio->dev))
			enable_irq_wake(i8042_ports[i].irq);
	}

	return 0;
}

static int i8042_pm_resume_noirq(struct device *dev)
{
	if (i8042_forcenorestore || !pm_resume_via_firmware())
		i8042_handle_data(0);

	return 0;
}

static int i8042_pm_resume(struct device *dev)
{
	bool want_reset;
	int i;

	for (i = 0; i < I8042_NUM_PORTS; i++) {
		struct serio *serio = i8042_ports[i].serio;

		if (serio && device_may_wakeup(&serio->dev))
			disable_irq_wake(i8042_ports[i].irq);
	}

	/*
	 * If platform firmware was not going to be involved in suspend, we did
	 * not restore the controller state to whatever it had been at boot
	 * time, so we do not need to do anything.
	 */
	if (i8042_forcenorestore || !pm_suspend_via_firmware())
		return 0;

	/*
	 * We only need to reset the controller if we are resuming after handing
	 * off control to the platform firmware, otherwise we can simply restore
	 * the mode.
	 */
	want_reset = pm_resume_via_firmware();

	return i8042_controller_resume(want_reset);
}

static int i8042_pm_thaw(struct device *dev)
{
	i8042_handle_data(0);

	return 0;
}

static int i8042_pm_reset(struct device *dev)
{
	i8042_controller_reset(false);

	return 0;
}

static int i8042_pm_restore(struct device *dev)
{
	return i8042_controller_resume(false);
}

static const struct dev_pm_ops i8042_pm_ops = {
	.suspend	= i8042_pm_suspend,
	.resume_noirq	= i8042_pm_resume_noirq,
	.resume		= i8042_pm_resume,
	.thaw		= i8042_pm_thaw,
	.poweroff	= i8042_pm_reset,
	.restore	= i8042_pm_restore,
};

#endif /* CONFIG_PM */

/*
 * We need to reset the 8042 back to original mode on system shutdown,
 * because otherwise BIOSes will be confused.
 */

static void i8042_shutdown(struct platform_device *dev)
{
	i8042_controller_reset(false);
}

static int i8042_create_kbd_port(void)
{
	struct serio *serio;
	struct i8042_port *port = &i8042_ports[I8042_KBD_PORT_NO];

	serio = kzalloc(sizeof(*serio), GFP_KERNEL);
	if (!serio)
		return -ENOMEM;

	serio->id.type		= i8042_direct ? SERIO_8042 : SERIO_8042_XL;
	serio->write		= i8042_dumbkbd ? NULL : i8042_kbd_write;
	serio->start		= i8042_start;
	serio->stop		= i8042_stop;
	serio->close		= i8042_port_close;
	serio->ps2_cmd_mutex	= &i8042_mutex;
	serio->port_data	= port;
	serio->dev.parent	= &i8042_platform_device->dev;
	strscpy(serio->name, "i8042 KBD port", sizeof(serio->name));
	strscpy(serio->phys, I8042_KBD_PHYS_DESC, sizeof(serio->phys));
	strscpy(serio->firmware_id, i8042_kbd_firmware_id,
		sizeof(serio->firmware_id));
	set_primary_fwnode(&serio->dev, i8042_kbd_fwnode);

	port->serio = serio;
	port->irq = I8042_KBD_IRQ;

	return 0;
}

static int i8042_create_aux_port(int idx)
{
	struct serio *serio;
	int port_no = idx < 0 ? I8042_AUX_PORT_NO : I8042_MUX_PORT_NO + idx;
	struct i8042_port *port = &i8042_ports[port_no];

	serio = kzalloc(sizeof(*serio), GFP_KERNEL);
	if (!serio)
		return -ENOMEM;

	serio->id.type		= SERIO_8042;
	serio->write		= i8042_aux_write;
	serio->start		= i8042_start;
	serio->stop		= i8042_stop;
	serio->ps2_cmd_mutex	= &i8042_mutex;
	serio->port_data	= port;
	serio->dev.parent	= &i8042_platform_device->dev;
	if (idx < 0) {
		strscpy(serio->name, "i8042 AUX port", sizeof(serio->name));
		strscpy(serio->phys, I8042_AUX_PHYS_DESC, sizeof(serio->phys));
		strscpy(serio->firmware_id, i8042_aux_firmware_id,
			sizeof(serio->firmware_id));
		serio->close = i8042_port_close;
	} else {
		snprintf(serio->name, sizeof(serio->name), "i8042 AUX%d port", idx);
		snprintf(serio->phys, sizeof(serio->phys), I8042_MUX_PHYS_DESC, idx + 1);
		strscpy(serio->firmware_id, i8042_aux_firmware_id,
			sizeof(serio->firmware_id));
	}

	port->serio = serio;
	port->mux = idx;
	port->irq = I8042_AUX_IRQ;

	return 0;
}

static void i8042_free_kbd_port(void)
{
	kfree(i8042_ports[I8042_KBD_PORT_NO].serio);
	i8042_ports[I8042_KBD_PORT_NO].serio = NULL;
}

static void i8042_free_aux_ports(void)
{
	int i;

	for (i = I8042_AUX_PORT_NO; i < I8042_NUM_PORTS; i++) {
		kfree(i8042_ports[i].serio);
		i8042_ports[i].serio = NULL;
	}
}

static void i8042_register_ports(void)
{
	int i;

	for (i = 0; i < I8042_NUM_PORTS; i++) {
		struct serio *serio = i8042_ports[i].serio;

		if (!serio)
			continue;

		printk(KERN_INFO "serio: %s at %#lx,%#lx irq %d\n",
			serio->name,
			(unsigned long) I8042_DATA_REG,
			(unsigned long) I8042_COMMAND_REG,
			i8042_ports[i].irq);
		serio_register_port(serio);
	}
}

static void i8042_unregister_ports(void)
{
	int i;

	for (i = 0; i < I8042_NUM_PORTS; i++) {
		if (i8042_ports[i].serio) {
			serio_unregister_port(i8042_ports[i].serio);
			i8042_ports[i].serio = NULL;
		}
	}
}

static void i8042_free_irqs(void)
{
	if (i8042_aux_irq_registered)
		free_irq(I8042_AUX_IRQ, i8042_platform_device);
	if (i8042_kbd_irq_registered)
		free_irq(I8042_KBD_IRQ, i8042_platform_device);

	i8042_aux_irq_registered = i8042_kbd_irq_registered = false;
}

static int i8042_setup_aux(void)
{
	int (*aux_enable)(void);
	int error;
	int i;

	if (i8042_check_aux())
		return -ENODEV;

	if (i8042_nomux || i8042_check_mux()) {
		error = i8042_create_aux_port(-1);
		if (error)
			goto err_free_ports;
		aux_enable = i8042_enable_aux_port;
	} else {
		for (i = 0; i < I8042_NUM_MUX_PORTS; i++) {
			error = i8042_create_aux_port(i);
			if (error)
				goto err_free_ports;
		}
		aux_enable = i8042_enable_mux_ports;
	}

	error = request_irq(I8042_AUX_IRQ, i8042_interrupt, IRQF_SHARED,
			    "i8042", i8042_platform_device);
	if (error)
		goto err_free_ports;

	error = aux_enable();
	if (error)
		goto err_free_irq;

	i8042_aux_irq_registered = true;
	return 0;

 err_free_irq:
	free_irq(I8042_AUX_IRQ, i8042_platform_device);
 err_free_ports:
	i8042_free_aux_ports();
	return error;
}

static int i8042_setup_kbd(void)
{
	int error;

	error = i8042_create_kbd_port();
	if (error)
		return error;

	error = request_irq(I8042_KBD_IRQ, i8042_interrupt, IRQF_SHARED,
			    "i8042", i8042_platform_device);
	if (error)
		goto err_free_port;

	error = i8042_enable_kbd_port();
	if (error)
		goto err_free_irq;

	i8042_kbd_irq_registered = true;
	return 0;

 err_free_irq:
	free_irq(I8042_KBD_IRQ, i8042_platform_device);
 err_free_port:
	i8042_free_kbd_port();
	return error;
}

static int i8042_kbd_bind_notifier(struct notifier_block *nb,
				   unsigned long action, void *data)
{
	struct device *dev = data;
	struct serio *serio = to_serio_port(dev);
	struct i8042_port *port = serio->port_data;

	if (serio != i8042_ports[I8042_KBD_PORT_NO].serio)
		return 0;

	switch (action) {
	case BUS_NOTIFY_BOUND_DRIVER:
		port->driver_bound = true;
		break;

	case BUS_NOTIFY_UNBIND_DRIVER:
		port->driver_bound = false;
		break;
	}

	return 0;
}

static int i8042_probe(struct platform_device *dev)
{
	int error;

	if (i8042_reset == I8042_RESET_ALWAYS) {
		error = i8042_controller_selftest();
		if (error)
			return error;
	}

	error = i8042_controller_init();
	if (error)
		return error;

#ifdef CONFIG_X86
	if (i8042_dritek)
		i8042_dritek_enable();
#endif

	if (!i8042_noaux) {
		error = i8042_setup_aux();
		if (error && error != -ENODEV && error != -EBUSY)
			goto out_fail;
	}

	if (!i8042_nokbd) {
		error = i8042_setup_kbd();
		if (error)
			goto out_fail;
	}
/*
 * Ok, everything is ready, let's register all serio ports
 */
	i8042_register_ports();

	return 0;

 out_fail:
	i8042_free_aux_ports();	/* in case KBD failed but AUX not */
	i8042_free_irqs();
	i8042_controller_reset(false);

	return error;
}

static void i8042_remove(struct platform_device *dev)
{
	i8042_unregister_ports();
	i8042_free_irqs();
	i8042_controller_reset(false);
}

static struct platform_driver i8042_driver = {
	.driver		= {
		.name	= "i8042",
#ifdef CONFIG_PM
		.pm	= &i8042_pm_ops,
#endif
	},
	.probe		= i8042_probe,
	.remove		= i8042_remove,
	.shutdown	= i8042_shutdown,
};

static struct notifier_block i8042_kbd_bind_notifier_block = {
	.notifier_call = i8042_kbd_bind_notifier,
};

static int __init i8042_init(void)
{
	int err;

	dbg_init();

	err = i8042_platform_init();
	if (err)
		return (err == -ENODEV) ? 0 : err;

	err = i8042_controller_check();
	if (err)
		goto err_platform_exit;

	/* Set this before creating the dev to allow i8042_command to work right away */
	i8042_present = true;

	err = platform_driver_register(&i8042_driver);
	if (err)
		goto err_platform_exit;

	i8042_platform_device = platform_device_alloc("i8042", -1);
	if (!i8042_platform_device) {
		err = -ENOMEM;
		goto err_unregister_driver;
	}

	err = platform_device_add(i8042_platform_device);
	if (err)
		goto err_free_device;

	bus_register_notifier(&serio_bus, &i8042_kbd_bind_notifier_block);
	panic_blink = i8042_panic_blink;

	return 0;

err_free_device:
	platform_device_put(i8042_platform_device);
err_unregister_driver:
	platform_driver_unregister(&i8042_driver);
 err_platform_exit:
	i8042_platform_exit();
	return err;
}

static void __exit i8042_exit(void)
{
	if (!i8042_present)
		return;

	platform_device_unregister(i8042_platform_device);
	platform_driver_unregister(&i8042_driver);
	i8042_platform_exit();

	bus_unregister_notifier(&serio_bus, &i8042_kbd_bind_notifier_block);
	panic_blink = NULL;
}

module_init(i8042_init);
module_exit(i8042_exit);