Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2191 insertions, 0 deletions

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
new file mode 100644
index 000000000..400281feb
--- /dev/null
+++ b/drivers/input/mouse/elantech.c
@@ -0,0 +1,2191 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Elantech Touchpad driver (v6)
+ *
+ * Copyright (C) 2007-2009 Arjan Opmeer <arjan@opmeer.net>
+ *
+ * Trademarks are the property of their respective owners.
+ */
+
+#include <linux/delay.h>
+#include <linux/dmi.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/platform_device.h>
+#include <linux/serio.h>
+#include <linux/libps2.h>
+#include <asm/unaligned.h>
+#include "psmouse.h"
+#include "elantech.h"
+#include "elan_i2c.h"
+
+#define elantech_debug(fmt, ...)					\
+	do {								\
+		if (etd->info.debug)					\
+			psmouse_printk(KERN_DEBUG, psmouse,		\
+					fmt, ##__VA_ARGS__);		\
+	} while (0)
+
+/*
+ * Send a Synaptics style sliced query command
+ */
+static int synaptics_send_cmd(struct psmouse *psmouse, unsigned char c,
+				unsigned char *param)
+{
+	if (ps2_sliced_command(&psmouse->ps2dev, c) ||
+	    ps2_command(&psmouse->ps2dev, param, PSMOUSE_CMD_GETINFO)) {
+		psmouse_err(psmouse, "%s query 0x%02x failed.\n", __func__, c);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * V3 and later support this fast command
+ */
+static int elantech_send_cmd(struct psmouse *psmouse, unsigned char c,
+				unsigned char *param)
+{
+	struct ps2dev *ps2dev = &psmouse->ps2dev;
+
+	if (ps2_command(ps2dev, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+	    ps2_command(ps2dev, NULL, c) ||
+	    ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO)) {
+		psmouse_err(psmouse, "%s query 0x%02x failed.\n", __func__, c);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * A retrying version of ps2_command
+ */
+static int elantech_ps2_command(struct psmouse *psmouse,
+				unsigned char *param, int command)
+{
+	struct ps2dev *ps2dev = &psmouse->ps2dev;
+	struct elantech_data *etd = psmouse->private;
+	int rc;
+	int tries = ETP_PS2_COMMAND_TRIES;
+
+	do {
+		rc = ps2_command(ps2dev, param, command);
+		if (rc == 0)
+			break;
+		tries--;
+		elantech_debug("retrying ps2 command 0x%02x (%d).\n",
+				command, tries);
+		msleep(ETP_PS2_COMMAND_DELAY);
+	} while (tries > 0);
+
+	if (rc)
+		psmouse_err(psmouse, "ps2 command 0x%02x failed.\n", command);
+
+	return rc;
+}
+
+/*
+ * Send an Elantech style special command to read 3 bytes from a register
+ */
+static int elantech_read_reg_params(struct psmouse *psmouse, u8 reg, u8 *param)
+{
+	if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+	    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
+	    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+	    elantech_ps2_command(psmouse, NULL, reg) ||
+	    elantech_ps2_command(psmouse, param, PSMOUSE_CMD_GETINFO)) {
+		psmouse_err(psmouse,
+			    "failed to read register %#02x\n", reg);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/*
+ * Send an Elantech style special command to write a register with a parameter
+ */
+static int elantech_write_reg_params(struct psmouse *psmouse, u8 reg, u8 *param)
+{
+	if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+	    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
+	    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+	    elantech_ps2_command(psmouse, NULL, reg) ||
+	    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+	    elantech_ps2_command(psmouse, NULL, param[0]) ||
+	    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+	    elantech_ps2_command(psmouse, NULL, param[1]) ||
+	    elantech_ps2_command(psmouse, NULL, PSMOUSE_CMD_SETSCALE11)) {
+		psmouse_err(psmouse,
+			    "failed to write register %#02x with value %#02x%#02x\n",
+			    reg, param[0], param[1]);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/*
+ * Send an Elantech style special command to read a value from a register
+ */
+static int elantech_read_reg(struct psmouse *psmouse, unsigned char reg,
+				unsigned char *val)
+{
+	struct elantech_data *etd = psmouse->private;
+	unsigned char param[3];
+	int rc = 0;
+
+	if (reg < 0x07 || reg > 0x26)
+		return -1;
+
+	if (reg > 0x11 && reg < 0x20)
+		return -1;
+
+	switch (etd->info.hw_version) {
+	case 1:
+		if (ps2_sliced_command(&psmouse->ps2dev, ETP_REGISTER_READ) ||
+		    ps2_sliced_command(&psmouse->ps2dev, reg) ||
+		    ps2_command(&psmouse->ps2dev, param, PSMOUSE_CMD_GETINFO)) {
+			rc = -1;
+		}
+		break;
+
+	case 2:
+		if (elantech_ps2_command(psmouse,  NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse,  NULL, ETP_REGISTER_READ) ||
+		    elantech_ps2_command(psmouse,  NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse,  NULL, reg) ||
+		    elantech_ps2_command(psmouse, param, PSMOUSE_CMD_GETINFO)) {
+			rc = -1;
+		}
+		break;
+
+	case 3 ... 4:
+		if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, reg) ||
+		    elantech_ps2_command(psmouse, param, PSMOUSE_CMD_GETINFO)) {
+			rc = -1;
+		}
+		break;
+	}
+
+	if (rc)
+		psmouse_err(psmouse, "failed to read register 0x%02x.\n", reg);
+	else if (etd->info.hw_version != 4)
+		*val = param[0];
+	else
+		*val = param[1];
+
+	return rc;
+}
+
+/*
+ * Send an Elantech style special command to write a register with a value
+ */
+static int elantech_write_reg(struct psmouse *psmouse, unsigned char reg,
+				unsigned char val)
+{
+	struct elantech_data *etd = psmouse->private;
+	int rc = 0;
+
+	if (reg < 0x07 || reg > 0x26)
+		return -1;
+
+	if (reg > 0x11 && reg < 0x20)
+		return -1;
+
+	switch (etd->info.hw_version) {
+	case 1:
+		if (ps2_sliced_command(&psmouse->ps2dev, ETP_REGISTER_WRITE) ||
+		    ps2_sliced_command(&psmouse->ps2dev, reg) ||
+		    ps2_sliced_command(&psmouse->ps2dev, val) ||
+		    ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_SETSCALE11)) {
+			rc = -1;
+		}
+		break;
+
+	case 2:
+		if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_WRITE) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, reg) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, val) ||
+		    elantech_ps2_command(psmouse, NULL, PSMOUSE_CMD_SETSCALE11)) {
+			rc = -1;
+		}
+		break;
+
+	case 3:
+		if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, reg) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, val) ||
+		    elantech_ps2_command(psmouse, NULL, PSMOUSE_CMD_SETSCALE11)) {
+			rc = -1;
+		}
+		break;
+
+	case 4:
+		if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, reg) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
+		    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
+		    elantech_ps2_command(psmouse, NULL, val) ||
+		    elantech_ps2_command(psmouse, NULL, PSMOUSE_CMD_SETSCALE11)) {
+			rc = -1;
+		}
+		break;
+	}
+
+	if (rc)
+		psmouse_err(psmouse,
+			    "failed to write register 0x%02x with value 0x%02x.\n",
+			    reg, val);
+
+	return rc;
+}
+
+/*
+ * Dump a complete mouse movement packet to the syslog
+ */
+static void elantech_packet_dump(struct psmouse *psmouse)
+{
+	psmouse_printk(KERN_DEBUG, psmouse, "PS/2 packet [%*ph]\n",
+		       psmouse->pktsize, psmouse->packet);
+}
+
+/*
+ * Advertise INPUT_PROP_BUTTONPAD for clickpads. The testing of bit 12 in
+ * fw_version for this is based on the following fw_version & caps table:
+ *
+ * Laptop-model:           fw_version:     caps:           buttons:
+ * Acer S3                 0x461f00        10, 13, 0e      clickpad
+ * Acer S7-392             0x581f01        50, 17, 0d      clickpad
+ * Acer V5-131             0x461f02        01, 16, 0c      clickpad
+ * Acer V5-551             0x461f00        ?               clickpad
+ * Asus K53SV              0x450f01        78, 15, 0c      2 hw buttons
+ * Asus G46VW              0x460f02        00, 18, 0c      2 hw buttons
+ * Asus G750JX             0x360f00        00, 16, 0c      2 hw buttons
+ * Asus TP500LN            0x381f17        10, 14, 0e      clickpad
+ * Asus X750JN             0x381f17        10, 14, 0e      clickpad
+ * Asus UX31               0x361f00        20, 15, 0e      clickpad
+ * Asus UX32VD             0x361f02        00, 15, 0e      clickpad
+ * Avatar AVIU-145A2       0x361f00        ?               clickpad
+ * Fujitsu CELSIUS H760    0x570f02        40, 14, 0c      3 hw buttons (**)
+ * Fujitsu CELSIUS H780    0x5d0f02        41, 16, 0d      3 hw buttons (**)
+ * Fujitsu LIFEBOOK E544   0x470f00        d0, 12, 09      2 hw buttons
+ * Fujitsu LIFEBOOK E546   0x470f00        50, 12, 09      2 hw buttons
+ * Fujitsu LIFEBOOK E547   0x470f00        50, 12, 09      2 hw buttons
+ * Fujitsu LIFEBOOK E554   0x570f01        40, 14, 0c      2 hw buttons
+ * Fujitsu LIFEBOOK E557   0x570f01        40, 14, 0c      2 hw buttons
+ * Fujitsu T725            0x470f01        05, 12, 09      2 hw buttons
+ * Fujitsu H730            0x570f00        c0, 14, 0c      3 hw buttons (**)
+ * Gigabyte U2442          0x450f01        58, 17, 0c      2 hw buttons
+ * Lenovo L430             0x350f02        b9, 15, 0c      2 hw buttons (*)
+ * Lenovo L530             0x350f02        b9, 15, 0c      2 hw buttons (*)
+ * Samsung NF210           0x150b00        78, 14, 0a      2 hw buttons
+ * Samsung NP770Z5E        0x575f01        10, 15, 0f      clickpad
+ * Samsung NP700Z5B        0x361f06        21, 15, 0f      clickpad
+ * Samsung NP900X3E-A02    0x575f03        ?               clickpad
+ * Samsung NP-QX410        0x851b00        19, 14, 0c      clickpad
+ * Samsung RC512           0x450f00        08, 15, 0c      2 hw buttons
+ * Samsung RF710           0x450f00        ?               2 hw buttons
+ * System76 Pangolin       0x250f01        ?               2 hw buttons
+ * (*) + 3 trackpoint buttons
+ * (**) + 0 trackpoint buttons
+ * Note: Lenovo L430 and Lenovo L530 have the same fw_version/caps
+ */
+static inline int elantech_is_buttonpad(struct elantech_device_info *info)
+{
+	return info->fw_version & 0x001000;
+}
+
+/*
+ * Interpret complete data packets and report absolute mode input events for
+ * hardware version 1. (4 byte packets)
+ */
+static void elantech_report_absolute_v1(struct psmouse *psmouse)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+	int fingers;
+
+	if (etd->info.fw_version < 0x020000) {
+		/*
+		 * byte 0:  D   U  p1  p2   1  p3   R   L
+		 * byte 1:  f   0  th  tw  x9  x8  y9  y8
+		 */
+		fingers = ((packet[1] & 0x80) >> 7) +
+				((packet[1] & 0x30) >> 4);
+	} else {
+		/*
+		 * byte 0: n1  n0  p2  p1   1  p3   R   L
+		 * byte 1:  0   0   0   0  x9  x8  y9  y8
+		 */
+		fingers = (packet[0] & 0xc0) >> 6;
+	}
+
+	if (etd->info.jumpy_cursor) {
+		if (fingers != 1) {
+			etd->single_finger_reports = 0;
+		} else if (etd->single_finger_reports < 2) {
+			/* Discard first 2 reports of one finger, bogus */
+			etd->single_finger_reports++;
+			elantech_debug("discarding packet\n");
+			return;
+		}
+	}
+
+	input_report_key(dev, BTN_TOUCH, fingers != 0);
+
+	/*
+	 * byte 2: x7  x6  x5  x4  x3  x2  x1  x0
+	 * byte 3: y7  y6  y5  y4  y3  y2  y1  y0
+	 */
+	if (fingers) {
+		input_report_abs(dev, ABS_X,
+			((packet[1] & 0x0c) << 6) | packet[2]);
+		input_report_abs(dev, ABS_Y,
+			etd->y_max - (((packet[1] & 0x03) << 8) | packet[3]));
+	}
+
+	input_report_key(dev, BTN_TOOL_FINGER, fingers == 1);
+	input_report_key(dev, BTN_TOOL_DOUBLETAP, fingers == 2);
+	input_report_key(dev, BTN_TOOL_TRIPLETAP, fingers == 3);
+
+	psmouse_report_standard_buttons(dev, packet[0]);
+
+	if (etd->info.fw_version < 0x020000 &&
+	    (etd->info.capabilities[0] & ETP_CAP_HAS_ROCKER)) {
+		/* rocker up */
+		input_report_key(dev, BTN_FORWARD, packet[0] & 0x40);
+		/* rocker down */
+		input_report_key(dev, BTN_BACK, packet[0] & 0x80);
+	}
+
+	input_sync(dev);
+}
+
+static void elantech_set_slot(struct input_dev *dev, int slot, bool active,
+			      unsigned int x, unsigned int y)
+{
+	input_mt_slot(dev, slot);
+	input_mt_report_slot_state(dev, MT_TOOL_FINGER, active);
+	if (active) {
+		input_report_abs(dev, ABS_MT_POSITION_X, x);
+		input_report_abs(dev, ABS_MT_POSITION_Y, y);
+	}
+}
+
+/* x1 < x2 and y1 < y2 when two fingers, x = y = 0 when not pressed */
+static void elantech_report_semi_mt_data(struct input_dev *dev,
+					 unsigned int num_fingers,
+					 unsigned int x1, unsigned int y1,
+					 unsigned int x2, unsigned int y2)
+{
+	elantech_set_slot(dev, 0, num_fingers != 0, x1, y1);
+	elantech_set_slot(dev, 1, num_fingers >= 2, x2, y2);
+}
+
+/*
+ * Interpret complete data packets and report absolute mode input events for
+ * hardware version 2. (6 byte packets)
+ */
+static void elantech_report_absolute_v2(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	struct input_dev *dev = psmouse->dev;
+	unsigned char *packet = psmouse->packet;
+	unsigned int fingers, x1 = 0, y1 = 0, x2 = 0, y2 = 0;
+	unsigned int width = 0, pres = 0;
+
+	/* byte 0: n1  n0   .   .   .   .   R   L */
+	fingers = (packet[0] & 0xc0) >> 6;
+
+	switch (fingers) {
+	case 3:
+		/*
+		 * Same as one finger, except report of more than 3 fingers:
+		 * byte 3:  n4  .   w1  w0   .   .   .   .
+		 */
+		if (packet[3] & 0x80)
+			fingers = 4;
+		fallthrough;
+	case 1:
+		/*
+		 * byte 1:  .   .   .   .  x11 x10 x9  x8
+		 * byte 2: x7  x6  x5  x4  x4  x2  x1  x0
+		 */
+		x1 = ((packet[1] & 0x0f) << 8) | packet[2];
+		/*
+		 * byte 4:  .   .   .   .  y11 y10 y9  y8
+		 * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
+		 */
+		y1 = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);
+
+		pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
+		width = ((packet[0] & 0x30) >> 2) | ((packet[3] & 0x30) >> 4);
+		break;
+
+	case 2:
+		/*
+		 * The coordinate of each finger is reported separately
+		 * with a lower resolution for two finger touches:
+		 * byte 0:  .   .  ay8 ax8  .   .   .   .
+		 * byte 1: ax7 ax6 ax5 ax4 ax3 ax2 ax1 ax0
+		 */
+		x1 = (((packet[0] & 0x10) << 4) | packet[1]) << 2;
+		/* byte 2: ay7 ay6 ay5 ay4 ay3 ay2 ay1 ay0 */
+		y1 = etd->y_max -
+			((((packet[0] & 0x20) << 3) | packet[2]) << 2);
+		/*
+		 * byte 3:  .   .  by8 bx8  .   .   .   .
+		 * byte 4: bx7 bx6 bx5 bx4 bx3 bx2 bx1 bx0
+		 */
+		x2 = (((packet[3] & 0x10) << 4) | packet[4]) << 2;
+		/* byte 5: by7 by8 by5 by4 by3 by2 by1 by0 */
+		y2 = etd->y_max -
+			((((packet[3] & 0x20) << 3) | packet[5]) << 2);
+
+		/* Unknown so just report sensible values */
+		pres = 127;
+		width = 7;
+		break;
+	}
+
+	input_report_key(dev, BTN_TOUCH, fingers != 0);
+	if (fingers != 0) {
+		input_report_abs(dev, ABS_X, x1);
+		input_report_abs(dev, ABS_Y, y1);
+	}
+	elantech_report_semi_mt_data(dev, fingers, x1, y1, x2, y2);
+	input_report_key(dev, BTN_TOOL_FINGER, fingers == 1);
+	input_report_key(dev, BTN_TOOL_DOUBLETAP, fingers == 2);
+	input_report_key(dev, BTN_TOOL_TRIPLETAP, fingers == 3);
+	input_report_key(dev, BTN_TOOL_QUADTAP, fingers == 4);
+	psmouse_report_standard_buttons(dev, packet[0]);
+	if (etd->info.reports_pressure) {
+		input_report_abs(dev, ABS_PRESSURE, pres);
+		input_report_abs(dev, ABS_TOOL_WIDTH, width);
+	}
+
+	input_sync(dev);
+}
+
+static void elantech_report_trackpoint(struct psmouse *psmouse,
+				       int packet_type)
+{
+	/*
+	 * byte 0:  0   0  sx  sy   0   M   R   L
+	 * byte 1:~sx   0   0   0   0   0   0   0
+	 * byte 2:~sy   0   0   0   0   0   0   0
+	 * byte 3:  0   0 ~sy ~sx   0   1   1   0
+	 * byte 4: x7  x6  x5  x4  x3  x2  x1  x0
+	 * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
+	 *
+	 * x and y are written in two's complement spread
+	 * over 9 bits with sx/sy the relative top bit and
+	 * x7..x0 and y7..y0 the lower bits.
+	 * The sign of y is opposite to what the input driver
+	 * expects for a relative movement
+	 */
+
+	struct elantech_data *etd = psmouse->private;
+	struct input_dev *tp_dev = etd->tp_dev;
+	unsigned char *packet = psmouse->packet;
+	int x, y;
+	u32 t;
+
+	t = get_unaligned_le32(&packet[0]);
+
+	switch (t & ~7U) {
+	case 0x06000030U:
+	case 0x16008020U:
+	case 0x26800010U:
+	case 0x36808000U:
+
+		/*
+		 * This firmware misreport coordinates for trackpoint
+		 * occasionally. Discard packets outside of [-127, 127] range
+		 * to prevent cursor jumps.
+		 */
+		if (packet[4] == 0x80 || packet[5] == 0x80 ||
+		    packet[1] >> 7 == packet[4] >> 7 ||
+		    packet[2] >> 7 == packet[5] >> 7) {
+			elantech_debug("discarding packet [%6ph]\n", packet);
+			break;
+
+		}
+		x = packet[4] - (int)((packet[1]^0x80) << 1);
+		y = (int)((packet[2]^0x80) << 1) - packet[5];
+
+		psmouse_report_standard_buttons(tp_dev, packet[0]);
+
+		input_report_rel(tp_dev, REL_X, x);
+		input_report_rel(tp_dev, REL_Y, y);
+
+		input_sync(tp_dev);
+
+		break;
+
+	default:
+		/* Dump unexpected packet sequences if debug=1 (default) */
+		if (etd->info.debug == 1)
+			elantech_packet_dump(psmouse);
+
+		break;
+	}
+}
+
+/*
+ * Interpret complete data packets and report absolute mode input events for
+ * hardware version 3. (12 byte packets for two fingers)
+ */
+static void elantech_report_absolute_v3(struct psmouse *psmouse,
+					int packet_type)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+	unsigned int fingers = 0, x1 = 0, y1 = 0, x2 = 0, y2 = 0;
+	unsigned int width = 0, pres = 0;
+
+	/* byte 0: n1  n0   .   .   .   .   R   L */
+	fingers = (packet[0] & 0xc0) >> 6;
+
+	switch (fingers) {
+	case 3:
+	case 1:
+		/*
+		 * byte 1:  .   .   .   .  x11 x10 x9  x8
+		 * byte 2: x7  x6  x5  x4  x4  x2  x1  x0
+		 */
+		x1 = ((packet[1] & 0x0f) << 8) | packet[2];
+		/*
+		 * byte 4:  .   .   .   .  y11 y10 y9  y8
+		 * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
+		 */
+		y1 = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);
+		break;
+
+	case 2:
+		if (packet_type == PACKET_V3_HEAD) {
+			/*
+			 * byte 1:   .    .    .    .  ax11 ax10 ax9  ax8
+			 * byte 2: ax7  ax6  ax5  ax4  ax3  ax2  ax1  ax0
+			 */
+			etd->mt[0].x = ((packet[1] & 0x0f) << 8) | packet[2];
+			/*
+			 * byte 4:   .    .    .    .  ay11 ay10 ay9  ay8
+			 * byte 5: ay7  ay6  ay5  ay4  ay3  ay2  ay1  ay0
+			 */
+			etd->mt[0].y = etd->y_max -
+				(((packet[4] & 0x0f) << 8) | packet[5]);
+			/*
+			 * wait for next packet
+			 */
+			return;
+		}
+
+		/* packet_type == PACKET_V3_TAIL */
+		x1 = etd->mt[0].x;
+		y1 = etd->mt[0].y;
+		x2 = ((packet[1] & 0x0f) << 8) | packet[2];
+		y2 = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);
+		break;
+	}
+
+	pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
+	width = ((packet[0] & 0x30) >> 2) | ((packet[3] & 0x30) >> 4);
+
+	input_report_key(dev, BTN_TOUCH, fingers != 0);
+	if (fingers != 0) {
+		input_report_abs(dev, ABS_X, x1);
+		input_report_abs(dev, ABS_Y, y1);
+	}
+	elantech_report_semi_mt_data(dev, fingers, x1, y1, x2, y2);
+	input_report_key(dev, BTN_TOOL_FINGER, fingers == 1);
+	input_report_key(dev, BTN_TOOL_DOUBLETAP, fingers == 2);
+	input_report_key(dev, BTN_TOOL_TRIPLETAP, fingers == 3);
+
+	/* For clickpads map both buttons to BTN_LEFT */
+	if (elantech_is_buttonpad(&etd->info))
+		input_report_key(dev, BTN_LEFT, packet[0] & 0x03);
+	else
+		psmouse_report_standard_buttons(dev, packet[0]);
+
+	input_report_abs(dev, ABS_PRESSURE, pres);
+	input_report_abs(dev, ABS_TOOL_WIDTH, width);
+
+	input_sync(dev);
+}
+
+static void elantech_input_sync_v4(struct psmouse *psmouse)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+
+	/* For clickpads map both buttons to BTN_LEFT */
+	if (elantech_is_buttonpad(&etd->info))
+		input_report_key(dev, BTN_LEFT, packet[0] & 0x03);
+	else
+		psmouse_report_standard_buttons(dev, packet[0]);
+
+	input_mt_report_pointer_emulation(dev, true);
+	input_sync(dev);
+}
+
+static void process_packet_status_v4(struct psmouse *psmouse)
+{
+	struct input_dev *dev = psmouse->dev;
+	unsigned char *packet = psmouse->packet;
+	unsigned fingers;
+	int i;
+
+	/* notify finger state change */
+	fingers = packet[1] & 0x1f;
+	for (i = 0; i < ETP_MAX_FINGERS; i++) {
+		if ((fingers & (1 << i)) == 0) {
+			input_mt_slot(dev, i);
+			input_mt_report_slot_state(dev, MT_TOOL_FINGER, false);
+		}
+	}
+
+	elantech_input_sync_v4(psmouse);
+}
+
+static void process_packet_head_v4(struct psmouse *psmouse)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+	int id;
+	int pres, traces;
+
+	id = ((packet[3] & 0xe0) >> 5) - 1;
+	if (id < 0 || id >= ETP_MAX_FINGERS)
+		return;
+
+	etd->mt[id].x = ((packet[1] & 0x0f) << 8) | packet[2];
+	etd->mt[id].y = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);
+	pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
+	traces = (packet[0] & 0xf0) >> 4;
+
+	input_mt_slot(dev, id);
+	input_mt_report_slot_state(dev, MT_TOOL_FINGER, true);
+
+	input_report_abs(dev, ABS_MT_POSITION_X, etd->mt[id].x);
+	input_report_abs(dev, ABS_MT_POSITION_Y, etd->mt[id].y);
+	input_report_abs(dev, ABS_MT_PRESSURE, pres);
+	input_report_abs(dev, ABS_MT_TOUCH_MAJOR, traces * etd->width);
+	/* report this for backwards compatibility */
+	input_report_abs(dev, ABS_TOOL_WIDTH, traces);
+
+	elantech_input_sync_v4(psmouse);
+}
+
+static void process_packet_motion_v4(struct psmouse *psmouse)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+	int weight, delta_x1 = 0, delta_y1 = 0, delta_x2 = 0, delta_y2 = 0;
+	int id, sid;
+
+	id = ((packet[0] & 0xe0) >> 5) - 1;
+	if (id < 0 || id >= ETP_MAX_FINGERS)
+		return;
+
+	sid = ((packet[3] & 0xe0) >> 5) - 1;
+	weight = (packet[0] & 0x10) ? ETP_WEIGHT_VALUE : 1;
+	/*
+	 * Motion packets give us the delta of x, y values of specific fingers,
+	 * but in two's complement. Let the compiler do the conversion for us.
+	 * Also _enlarge_ the numbers to int, in case of overflow.
+	 */
+	delta_x1 = (signed char)packet[1];
+	delta_y1 = (signed char)packet[2];
+	delta_x2 = (signed char)packet[4];
+	delta_y2 = (signed char)packet[5];
+
+	etd->mt[id].x += delta_x1 * weight;
+	etd->mt[id].y -= delta_y1 * weight;
+	input_mt_slot(dev, id);
+	input_report_abs(dev, ABS_MT_POSITION_X, etd->mt[id].x);
+	input_report_abs(dev, ABS_MT_POSITION_Y, etd->mt[id].y);
+
+	if (sid >= 0 && sid < ETP_MAX_FINGERS) {
+		etd->mt[sid].x += delta_x2 * weight;
+		etd->mt[sid].y -= delta_y2 * weight;
+		input_mt_slot(dev, sid);
+		input_report_abs(dev, ABS_MT_POSITION_X, etd->mt[sid].x);
+		input_report_abs(dev, ABS_MT_POSITION_Y, etd->mt[sid].y);
+	}
+
+	elantech_input_sync_v4(psmouse);
+}
+
+static void elantech_report_absolute_v4(struct psmouse *psmouse,
+					int packet_type)
+{
+	switch (packet_type) {
+	case PACKET_V4_STATUS:
+		process_packet_status_v4(psmouse);
+		break;
+
+	case PACKET_V4_HEAD:
+		process_packet_head_v4(psmouse);
+		break;
+
+	case PACKET_V4_MOTION:
+		process_packet_motion_v4(psmouse);
+		break;
+
+	case PACKET_UNKNOWN:
+	default:
+		/* impossible to get here */
+		break;
+	}
+}
+
+static int elantech_packet_check_v1(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+	unsigned char p1, p2, p3;
+
+	/* Parity bits are placed differently */
+	if (etd->info.fw_version < 0x020000) {
+		/* byte 0:  D   U  p1  p2   1  p3   R   L */
+		p1 = (packet[0] & 0x20) >> 5;
+		p2 = (packet[0] & 0x10) >> 4;
+	} else {
+		/* byte 0: n1  n0  p2  p1   1  p3   R   L */
+		p1 = (packet[0] & 0x10) >> 4;
+		p2 = (packet[0] & 0x20) >> 5;
+	}
+
+	p3 = (packet[0] & 0x04) >> 2;
+
+	return etd->parity[packet[1]] == p1 &&
+	       etd->parity[packet[2]] == p2 &&
+	       etd->parity[packet[3]] == p3;
+}
+
+static int elantech_debounce_check_v2(struct psmouse *psmouse)
+{
+        /*
+         * When we encounter packet that matches this exactly, it means the
+         * hardware is in debounce status. Just ignore the whole packet.
+         */
+	static const u8 debounce_packet[] = {
+		0x84, 0xff, 0xff, 0x02, 0xff, 0xff
+	};
+        unsigned char *packet = psmouse->packet;
+
+        return !memcmp(packet, debounce_packet, sizeof(debounce_packet));
+}
+
+static int elantech_packet_check_v2(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+
+	/*
+	 * V2 hardware has two flavors. Older ones that do not report pressure,
+	 * and newer ones that reports pressure and width. With newer ones, all
+	 * packets (1, 2, 3 finger touch) have the same constant bits. With
+	 * older ones, 1/3 finger touch packets and 2 finger touch packets
+	 * have different constant bits.
+	 * With all three cases, if the constant bits are not exactly what I
+	 * expected, I consider them invalid.
+	 */
+	if (etd->info.reports_pressure)
+		return (packet[0] & 0x0c) == 0x04 &&
+		       (packet[3] & 0x0f) == 0x02;
+
+	if ((packet[0] & 0xc0) == 0x80)
+		return (packet[0] & 0x0c) == 0x0c &&
+		       (packet[3] & 0x0e) == 0x08;
+
+	return (packet[0] & 0x3c) == 0x3c &&
+	       (packet[1] & 0xf0) == 0x00 &&
+	       (packet[3] & 0x3e) == 0x38 &&
+	       (packet[4] & 0xf0) == 0x00;
+}
+
+/*
+ * We check the constant bits to determine what packet type we get,
+ * so packet checking is mandatory for v3 and later hardware.
+ */
+static int elantech_packet_check_v3(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	static const u8 debounce_packet[] = {
+		0xc4, 0xff, 0xff, 0x02, 0xff, 0xff
+	};
+	unsigned char *packet = psmouse->packet;
+
+	/*
+	 * check debounce first, it has the same signature in byte 0
+	 * and byte 3 as PACKET_V3_HEAD.
+	 */
+	if (!memcmp(packet, debounce_packet, sizeof(debounce_packet)))
+		return PACKET_DEBOUNCE;
+
+	/*
+	 * If the hardware flag 'crc_enabled' is set the packets have
+	 * different signatures.
+	 */
+	if (etd->info.crc_enabled) {
+		if ((packet[3] & 0x09) == 0x08)
+			return PACKET_V3_HEAD;
+
+		if ((packet[3] & 0x09) == 0x09)
+			return PACKET_V3_TAIL;
+	} else {
+		if ((packet[0] & 0x0c) == 0x04 && (packet[3] & 0xcf) == 0x02)
+			return PACKET_V3_HEAD;
+
+		if ((packet[0] & 0x0c) == 0x0c && (packet[3] & 0xce) == 0x0c)
+			return PACKET_V3_TAIL;
+		if ((packet[3] & 0x0f) == 0x06)
+			return PACKET_TRACKPOINT;
+	}
+
+	return PACKET_UNKNOWN;
+}
+
+static int elantech_packet_check_v4(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+	unsigned char packet_type = packet[3] & 0x03;
+	unsigned int ic_version;
+	bool sanity_check;
+
+	if (etd->tp_dev && (packet[3] & 0x0f) == 0x06)
+		return PACKET_TRACKPOINT;
+
+	/* This represents the version of IC body. */
+	ic_version = (etd->info.fw_version & 0x0f0000) >> 16;
+
+	/*
+	 * Sanity check based on the constant bits of a packet.
+	 * The constant bits change depending on the value of
+	 * the hardware flag 'crc_enabled' and the version of
+	 * the IC body, but are the same for every packet,
+	 * regardless of the type.
+	 */
+	if (etd->info.crc_enabled)
+		sanity_check = ((packet[3] & 0x08) == 0x00);
+	else if (ic_version == 7 && etd->info.samples[1] == 0x2A)
+		sanity_check = ((packet[3] & 0x1c) == 0x10);
+	else
+		sanity_check = ((packet[0] & 0x08) == 0x00 &&
+				(packet[3] & 0x1c) == 0x10);
+
+	if (!sanity_check)
+		return PACKET_UNKNOWN;
+
+	switch (packet_type) {
+	case 0:
+		return PACKET_V4_STATUS;
+
+	case 1:
+		return PACKET_V4_HEAD;
+
+	case 2:
+		return PACKET_V4_MOTION;
+	}
+
+	return PACKET_UNKNOWN;
+}
+
+/*
+ * Process byte stream from mouse and handle complete packets
+ */
+static psmouse_ret_t elantech_process_byte(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	int packet_type;
+
+	if (psmouse->pktcnt < psmouse->pktsize)
+		return PSMOUSE_GOOD_DATA;
+
+	if (etd->info.debug > 1)
+		elantech_packet_dump(psmouse);
+
+	switch (etd->info.hw_version) {
+	case 1:
+		if (etd->info.paritycheck && !elantech_packet_check_v1(psmouse))
+			return PSMOUSE_BAD_DATA;
+
+		elantech_report_absolute_v1(psmouse);
+		break;
+
+	case 2:
+		/* ignore debounce */
+		if (elantech_debounce_check_v2(psmouse))
+			return PSMOUSE_FULL_PACKET;
+
+		if (etd->info.paritycheck && !elantech_packet_check_v2(psmouse))
+			return PSMOUSE_BAD_DATA;
+
+		elantech_report_absolute_v2(psmouse);
+		break;
+
+	case 3:
+		packet_type = elantech_packet_check_v3(psmouse);
+		switch (packet_type) {
+		case PACKET_UNKNOWN:
+			return PSMOUSE_BAD_DATA;
+
+		case PACKET_DEBOUNCE:
+			/* ignore debounce */
+			break;
+
+		case PACKET_TRACKPOINT:
+			elantech_report_trackpoint(psmouse, packet_type);
+			break;
+
+		default:
+			elantech_report_absolute_v3(psmouse, packet_type);
+			break;
+		}
+
+		break;
+
+	case 4:
+		packet_type = elantech_packet_check_v4(psmouse);
+		switch (packet_type) {
+		case PACKET_UNKNOWN:
+			return PSMOUSE_BAD_DATA;
+
+		case PACKET_TRACKPOINT:
+			elantech_report_trackpoint(psmouse, packet_type);
+			break;
+
+		default:
+			elantech_report_absolute_v4(psmouse, packet_type);
+			break;
+		}
+
+		break;
+	}
+
+	return PSMOUSE_FULL_PACKET;
+}
+
+/*
+ * This writes the reg_07 value again to the hardware at the end of every
+ * set_rate call because the register loses its value. reg_07 allows setting
+ * absolute mode on v4 hardware
+ */
+static void elantech_set_rate_restore_reg_07(struct psmouse *psmouse,
+		unsigned int rate)
+{
+	struct elantech_data *etd = psmouse->private;
+
+	etd->original_set_rate(psmouse, rate);
+	if (elantech_write_reg(psmouse, 0x07, etd->reg_07))
+		psmouse_err(psmouse, "restoring reg_07 failed\n");
+}
+
+/*
+ * Put the touchpad into absolute mode
+ */
+static int elantech_set_absolute_mode(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	unsigned char val;
+	int tries = ETP_READ_BACK_TRIES;
+	int rc = 0;
+
+	switch (etd->info.hw_version) {
+	case 1:
+		etd->reg_10 = 0x16;
+		etd->reg_11 = 0x8f;
+		if (elantech_write_reg(psmouse, 0x10, etd->reg_10) ||
+		    elantech_write_reg(psmouse, 0x11, etd->reg_11)) {
+			rc = -1;
+		}
+		break;
+
+	case 2:
+					/* Windows driver values */
+		etd->reg_10 = 0x54;
+		etd->reg_11 = 0x88;	/* 0x8a */
+		etd->reg_21 = 0x60;	/* 0x00 */
+		if (elantech_write_reg(psmouse, 0x10, etd->reg_10) ||
+		    elantech_write_reg(psmouse, 0x11, etd->reg_11) ||
+		    elantech_write_reg(psmouse, 0x21, etd->reg_21)) {
+			rc = -1;
+		}
+		break;
+
+	case 3:
+		if (etd->info.set_hw_resolution)
+			etd->reg_10 = 0x0b;
+		else
+			etd->reg_10 = 0x01;
+
+		if (elantech_write_reg(psmouse, 0x10, etd->reg_10))
+			rc = -1;
+
+		break;
+
+	case 4:
+		etd->reg_07 = 0x01;
+		if (elantech_write_reg(psmouse, 0x07, etd->reg_07))
+			rc = -1;
+
+		goto skip_readback_reg_10; /* v4 has no reg 0x10 to read */
+	}
+
+	if (rc == 0) {
+		/*
+		 * Read back reg 0x10. For hardware version 1 we must make
+		 * sure the absolute mode bit is set. For hardware version 2
+		 * the touchpad is probably initializing and not ready until
+		 * we read back the value we just wrote.
+		 */
+		do {
+			rc = elantech_read_reg(psmouse, 0x10, &val);
+			if (rc == 0)
+				break;
+			tries--;
+			elantech_debug("retrying read (%d).\n", tries);
+			msleep(ETP_READ_BACK_DELAY);
+		} while (tries > 0);
+
+		if (rc) {
+			psmouse_err(psmouse,
+				    "failed to read back register 0x10.\n");
+		} else if (etd->info.hw_version == 1 &&
+			   !(val & ETP_R10_ABSOLUTE_MODE)) {
+			psmouse_err(psmouse,
+				    "touchpad refuses to switch to absolute mode.\n");
+			rc = -1;
+		}
+	}
+
+ skip_readback_reg_10:
+	if (rc)
+		psmouse_err(psmouse, "failed to initialise registers.\n");
+
+	return rc;
+}
+
+/*
+ * (value from firmware) * 10 + 790 = dpi
+ * we also have to convert dpi to dots/mm (*10/254 to avoid floating point)
+ */
+static unsigned int elantech_convert_res(unsigned int val)
+{
+	return (val * 10 + 790) * 10 / 254;
+}
+
+static int elantech_get_resolution_v4(struct psmouse *psmouse,
+				      unsigned int *x_res,
+				      unsigned int *y_res,
+				      unsigned int *bus)
+{
+	unsigned char param[3];
+
+	if (elantech_send_cmd(psmouse, ETP_RESOLUTION_QUERY, param))
+		return -1;
+
+	*x_res = elantech_convert_res(param[1] & 0x0f);
+	*y_res = elantech_convert_res((param[1] & 0xf0) >> 4);
+	*bus = param[2];
+
+	return 0;
+}
+
+static void elantech_set_buttonpad_prop(struct psmouse *psmouse)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct elantech_data *etd = psmouse->private;
+
+	if (elantech_is_buttonpad(&etd->info)) {
+		__set_bit(INPUT_PROP_BUTTONPAD, dev->propbit);
+		__clear_bit(BTN_RIGHT, dev->keybit);
+	}
+}
+
+/*
+ * Some hw_version 4 models do have a middle button
+ */
+static const struct dmi_system_id elantech_dmi_has_middle_button[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+	{
+		/* Fujitsu H730 has a middle button */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CELSIUS H730"),
+		},
+	},
+	{
+		/* Fujitsu H760 also has a middle button */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CELSIUS H760"),
+		},
+	},
+	{
+		/* Fujitsu H780 also has a middle button */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CELSIUS H780"),
+		},
+	},
+#endif
+	{ }
+};
+
+/*
+ * Set the appropriate event bits for the input subsystem
+ */
+static int elantech_set_input_params(struct psmouse *psmouse)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct elantech_data *etd = psmouse->private;
+	struct elantech_device_info *info = &etd->info;
+	unsigned int x_min = info->x_min, y_min = info->y_min,
+		     x_max = info->x_max, y_max = info->y_max,
+		     width = info->width;
+
+	__set_bit(INPUT_PROP_POINTER, dev->propbit);
+	__set_bit(EV_KEY, dev->evbit);
+	__set_bit(EV_ABS, dev->evbit);
+	__clear_bit(EV_REL, dev->evbit);
+
+	__set_bit(BTN_LEFT, dev->keybit);
+	if (info->has_middle_button)
+		__set_bit(BTN_MIDDLE, dev->keybit);
+	__set_bit(BTN_RIGHT, dev->keybit);
+
+	__set_bit(BTN_TOUCH, dev->keybit);
+	__set_bit(BTN_TOOL_FINGER, dev->keybit);
+	__set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
+	__set_bit(BTN_TOOL_TRIPLETAP, dev->keybit);
+
+	switch (info->hw_version) {
+	case 1:
+		/* Rocker button */
+		if (info->fw_version < 0x020000 &&
+		    (info->capabilities[0] & ETP_CAP_HAS_ROCKER)) {
+			__set_bit(BTN_FORWARD, dev->keybit);
+			__set_bit(BTN_BACK, dev->keybit);
+		}
+		input_set_abs_params(dev, ABS_X, x_min, x_max, 0, 0);
+		input_set_abs_params(dev, ABS_Y, y_min, y_max, 0, 0);
+		break;
+
+	case 2:
+		__set_bit(BTN_TOOL_QUADTAP, dev->keybit);
+		__set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
+		fallthrough;
+	case 3:
+		if (info->hw_version == 3)
+			elantech_set_buttonpad_prop(psmouse);
+		input_set_abs_params(dev, ABS_X, x_min, x_max, 0, 0);
+		input_set_abs_params(dev, ABS_Y, y_min, y_max, 0, 0);
+		if (info->reports_pressure) {
+			input_set_abs_params(dev, ABS_PRESSURE, ETP_PMIN_V2,
+					     ETP_PMAX_V2, 0, 0);
+			input_set_abs_params(dev, ABS_TOOL_WIDTH, ETP_WMIN_V2,
+					     ETP_WMAX_V2, 0, 0);
+		}
+		input_mt_init_slots(dev, 2, INPUT_MT_SEMI_MT);
+		input_set_abs_params(dev, ABS_MT_POSITION_X, x_min, x_max, 0, 0);
+		input_set_abs_params(dev, ABS_MT_POSITION_Y, y_min, y_max, 0, 0);
+		break;
+
+	case 4:
+		elantech_set_buttonpad_prop(psmouse);
+		__set_bit(BTN_TOOL_QUADTAP, dev->keybit);
+		/* For X to recognize me as touchpad. */
+		input_set_abs_params(dev, ABS_X, x_min, x_max, 0, 0);
+		input_set_abs_params(dev, ABS_Y, y_min, y_max, 0, 0);
+		/*
+		 * range of pressure and width is the same as v2,
+		 * report ABS_PRESSURE, ABS_TOOL_WIDTH for compatibility.
+		 */
+		input_set_abs_params(dev, ABS_PRESSURE, ETP_PMIN_V2,
+				     ETP_PMAX_V2, 0, 0);
+		input_set_abs_params(dev, ABS_TOOL_WIDTH, ETP_WMIN_V2,
+				     ETP_WMAX_V2, 0, 0);
+		/* Multitouch capable pad, up to 5 fingers. */
+		input_mt_init_slots(dev, ETP_MAX_FINGERS, 0);
+		input_set_abs_params(dev, ABS_MT_POSITION_X, x_min, x_max, 0, 0);
+		input_set_abs_params(dev, ABS_MT_POSITION_Y, y_min, y_max, 0, 0);
+		input_set_abs_params(dev, ABS_MT_PRESSURE, ETP_PMIN_V2,
+				     ETP_PMAX_V2, 0, 0);
+		/*
+		 * The firmware reports how many trace lines the finger spans,
+		 * convert to surface unit as Protocol-B requires.
+		 */
+		input_set_abs_params(dev, ABS_MT_TOUCH_MAJOR, 0,
+				     ETP_WMAX_V2 * width, 0, 0);
+		break;
+	}
+
+	input_abs_set_res(dev, ABS_X, info->x_res);
+	input_abs_set_res(dev, ABS_Y, info->y_res);
+	if (info->hw_version > 1) {
+		input_abs_set_res(dev, ABS_MT_POSITION_X, info->x_res);
+		input_abs_set_res(dev, ABS_MT_POSITION_Y, info->y_res);
+	}
+
+	etd->y_max = y_max;
+	etd->width = width;
+
+	return 0;
+}
+
+struct elantech_attr_data {
+	size_t		field_offset;
+	unsigned char	reg;
+};
+
+/*
+ * Display a register value by reading a sysfs entry
+ */
+static ssize_t elantech_show_int_attr(struct psmouse *psmouse, void *data,
+					char *buf)
+{
+	struct elantech_data *etd = psmouse->private;
+	struct elantech_attr_data *attr = data;
+	unsigned char *reg = (unsigned char *) etd + attr->field_offset;
+	int rc = 0;
+
+	if (attr->reg)
+		rc = elantech_read_reg(psmouse, attr->reg, reg);
+
+	return sprintf(buf, "0x%02x\n", (attr->reg && rc) ? -1 : *reg);
+}
+
+/*
+ * Write a register value by writing a sysfs entry
+ */
+static ssize_t elantech_set_int_attr(struct psmouse *psmouse,
+				     void *data, const char *buf, size_t count)
+{
+	struct elantech_data *etd = psmouse->private;
+	struct elantech_attr_data *attr = data;
+	unsigned char *reg = (unsigned char *) etd + attr->field_offset;
+	unsigned char value;
+	int err;
+
+	err = kstrtou8(buf, 16, &value);
+	if (err)
+		return err;
+
+	/* Do we need to preserve some bits for version 2 hardware too? */
+	if (etd->info.hw_version == 1) {
+		if (attr->reg == 0x10)
+			/* Force absolute mode always on */
+			value |= ETP_R10_ABSOLUTE_MODE;
+		else if (attr->reg == 0x11)
+			/* Force 4 byte mode always on */
+			value |= ETP_R11_4_BYTE_MODE;
+	}
+
+	if (!attr->reg || elantech_write_reg(psmouse, attr->reg, value) == 0)
+		*reg = value;
+
+	return count;
+}
+
+#define ELANTECH_INT_ATTR(_name, _register)				\
+	static struct elantech_attr_data elantech_attr_##_name = {	\
+		.field_offset = offsetof(struct elantech_data, _name),	\
+		.reg = _register,					\
+	};								\
+	PSMOUSE_DEFINE_ATTR(_name, 0644,				\
+			    &elantech_attr_##_name,			\
+			    elantech_show_int_attr,			\
+			    elantech_set_int_attr)
+
+#define ELANTECH_INFO_ATTR(_name)					       \
+	static struct elantech_attr_data elantech_attr_##_name = {	       \
+		.field_offset = offsetof(struct elantech_data, info) +	       \
+				offsetof(struct elantech_device_info, _name),  \
+		.reg = 0,						       \
+	};								       \
+	PSMOUSE_DEFINE_ATTR(_name, 0644,				       \
+			    &elantech_attr_##_name,			       \
+			    elantech_show_int_attr,			       \
+			    elantech_set_int_attr)
+
+ELANTECH_INT_ATTR(reg_07, 0x07);
+ELANTECH_INT_ATTR(reg_10, 0x10);
+ELANTECH_INT_ATTR(reg_11, 0x11);
+ELANTECH_INT_ATTR(reg_20, 0x20);
+ELANTECH_INT_ATTR(reg_21, 0x21);
+ELANTECH_INT_ATTR(reg_22, 0x22);
+ELANTECH_INT_ATTR(reg_23, 0x23);
+ELANTECH_INT_ATTR(reg_24, 0x24);
+ELANTECH_INT_ATTR(reg_25, 0x25);
+ELANTECH_INT_ATTR(reg_26, 0x26);
+ELANTECH_INFO_ATTR(debug);
+ELANTECH_INFO_ATTR(paritycheck);
+ELANTECH_INFO_ATTR(crc_enabled);
+
+static struct attribute *elantech_attrs[] = {
+	&psmouse_attr_reg_07.dattr.attr,
+	&psmouse_attr_reg_10.dattr.attr,
+	&psmouse_attr_reg_11.dattr.attr,
+	&psmouse_attr_reg_20.dattr.attr,
+	&psmouse_attr_reg_21.dattr.attr,
+	&psmouse_attr_reg_22.dattr.attr,
+	&psmouse_attr_reg_23.dattr.attr,
+	&psmouse_attr_reg_24.dattr.attr,
+	&psmouse_attr_reg_25.dattr.attr,
+	&psmouse_attr_reg_26.dattr.attr,
+	&psmouse_attr_debug.dattr.attr,
+	&psmouse_attr_paritycheck.dattr.attr,
+	&psmouse_attr_crc_enabled.dattr.attr,
+	NULL
+};
+
+static const struct attribute_group elantech_attr_group = {
+	.attrs = elantech_attrs,
+};
+
+static bool elantech_is_signature_valid(const unsigned char *param)
+{
+	static const unsigned char rates[] = { 200, 100, 80, 60, 40, 20, 10 };
+	int i;
+
+	if (param[0] == 0)
+		return false;
+
+	if (param[1] == 0)
+		return true;
+
+	/*
+	 * Some hw_version >= 4 models have a revision higher then 20. Meaning
+	 * that param[2] may be 10 or 20, skip the rates check for these.
+	 */
+	if ((param[0] & 0x0f) >= 0x06 && (param[1] & 0xaf) == 0x0f &&
+	    param[2] < 40)
+		return true;
+
+	for (i = 0; i < ARRAY_SIZE(rates); i++)
+		if (param[2] == rates[i])
+			return false;
+
+	return true;
+}
+
+/*
+ * Use magic knock to detect Elantech touchpad
+ */
+int elantech_detect(struct psmouse *psmouse, bool set_properties)
+{
+	struct ps2dev *ps2dev = &psmouse->ps2dev;
+	unsigned char param[3];
+
+	ps2_command(ps2dev, NULL, PSMOUSE_CMD_RESET_DIS);
+
+	if (ps2_command(ps2dev,  NULL, PSMOUSE_CMD_DISABLE) ||
+	    ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11) ||
+	    ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11) ||
+	    ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11) ||
+	    ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO)) {
+		psmouse_dbg(psmouse, "sending Elantech magic knock failed.\n");
+		return -1;
+	}
+
+	/*
+	 * Report this in case there are Elantech models that use a different
+	 * set of magic numbers
+	 */
+	if (param[0] != 0x3c || param[1] != 0x03 ||
+	    (param[2] != 0xc8 && param[2] != 0x00)) {
+		psmouse_dbg(psmouse,
+			    "unexpected magic knock result 0x%02x, 0x%02x, 0x%02x.\n",
+			    param[0], param[1], param[2]);
+		return -1;
+	}
+
+	/*
+	 * Query touchpad's firmware version and see if it reports known
+	 * value to avoid mis-detection. Logitech mice are known to respond
+	 * to Elantech magic knock and there might be more.
+	 */
+	if (synaptics_send_cmd(psmouse, ETP_FW_VERSION_QUERY, param)) {
+		psmouse_dbg(psmouse, "failed to query firmware version.\n");
+		return -1;
+	}
+
+	psmouse_dbg(psmouse,
+		    "Elantech version query result 0x%02x, 0x%02x, 0x%02x.\n",
+		    param[0], param[1], param[2]);
+
+	if (!elantech_is_signature_valid(param)) {
+		psmouse_dbg(psmouse,
+			    "Probably not a real Elantech touchpad. Aborting.\n");
+		return -1;
+	}
+
+	if (set_properties) {
+		psmouse->vendor = "Elantech";
+		psmouse->name = "Touchpad";
+	}
+
+	return 0;
+}
+
+/*
+ * Clean up sysfs entries when disconnecting
+ */
+static void elantech_disconnect(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+
+	/*
+	 * We might have left a breadcrumb when trying to
+	 * set up SMbus companion.
+	 */
+	psmouse_smbus_cleanup(psmouse);
+
+	if (etd->tp_dev)
+		input_unregister_device(etd->tp_dev);
+	sysfs_remove_group(&psmouse->ps2dev.serio->dev.kobj,
+			   &elantech_attr_group);
+	kfree(psmouse->private);
+	psmouse->private = NULL;
+}
+
+/*
+ * Put the touchpad back into absolute mode when reconnecting
+ */
+static int elantech_reconnect(struct psmouse *psmouse)
+{
+	psmouse_reset(psmouse);
+
+	if (elantech_detect(psmouse, 0))
+		return -1;
+
+	if (elantech_set_absolute_mode(psmouse)) {
+		psmouse_err(psmouse,
+			    "failed to put touchpad back into absolute mode.\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Some hw_version 4 models do not work with crc_disabled
+ */
+static const struct dmi_system_id elantech_dmi_force_crc_enabled[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+	{
+		/* Fujitsu H730 does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CELSIUS H730"),
+		},
+	},
+	{
+		/* Fujitsu H760 does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CELSIUS H760"),
+		},
+	},
+	{
+		/* Fujitsu LIFEBOOK E544  does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK E544"),
+		},
+	},
+	{
+		/* Fujitsu LIFEBOOK E546  does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK E546"),
+		},
+	},
+	{
+		/* Fujitsu LIFEBOOK E547 does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK E547"),
+		},
+	},
+	{
+		/* Fujitsu LIFEBOOK E554  does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK E554"),
+		},
+	},
+	{
+		/* Fujitsu LIFEBOOK E556 does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK E556"),
+		},
+	},
+	{
+		/* Fujitsu LIFEBOOK E557 does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK E557"),
+		},
+	},
+	{
+		/* Fujitsu LIFEBOOK U745 does not work with crc_enabled == 0 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK U745"),
+		},
+	},
+#endif
+	{ }
+};
+
+/*
+ * Some hw_version 3 models go into error state when we try to set
+ * bit 3 and/or bit 1 of r10.
+ */
+static const struct dmi_system_id no_hw_res_dmi_table[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+	{
+		/* Gigabyte U2442 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "GIGABYTE"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "U2442"),
+		},
+	},
+#endif
+	{ }
+};
+
+/*
+ * Change Report id 0x5E to 0x5F.
+ */
+static int elantech_change_report_id(struct psmouse *psmouse)
+{
+	/*
+	 * NOTE: the code is expecting to receive param[] as an array of 3
+	 * items (see __ps2_command()), even if in this case only 2 are
+	 * actually needed. Make sure the array size is 3 to avoid potential
+	 * stack out-of-bound accesses.
+	 */
+	unsigned char param[3] = { 0x10, 0x03 };
+
+	if (elantech_write_reg_params(psmouse, 0x7, param) ||
+	    elantech_read_reg_params(psmouse, 0x7, param) ||
+	    param[0] != 0x10 || param[1] != 0x03) {
+		psmouse_err(psmouse, "Unable to change report ID to 0x5f.\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+/*
+ * determine hardware version and set some properties according to it.
+ */
+static int elantech_set_properties(struct elantech_device_info *info)
+{
+	/* This represents the version of IC body. */
+	info->ic_version = (info->fw_version & 0x0f0000) >> 16;
+
+	/* Early version of Elan touchpads doesn't obey the rule. */
+	if (info->fw_version < 0x020030 || info->fw_version == 0x020600)
+		info->hw_version = 1;
+	else {
+		switch (info->ic_version) {
+		case 2:
+		case 4:
+			info->hw_version = 2;
+			break;
+		case 5:
+			info->hw_version = 3;
+			break;
+		case 6 ... 15:
+			info->hw_version = 4;
+			break;
+		default:
+			return -1;
+		}
+	}
+
+	/* Get information pattern for hw_version 4 */
+	info->pattern = 0x00;
+	if (info->ic_version == 0x0f && (info->fw_version & 0xff) <= 0x02)
+		info->pattern = info->fw_version & 0xff;
+
+	/* decide which send_cmd we're gonna use early */
+	info->send_cmd = info->hw_version >= 3 ? elantech_send_cmd :
+						 synaptics_send_cmd;
+
+	/* Turn on packet checking by default */
+	info->paritycheck = 1;
+
+	/*
+	 * This firmware suffers from misreporting coordinates when
+	 * a touch action starts causing the mouse cursor or scrolled page
+	 * to jump. Enable a workaround.
+	 */
+	info->jumpy_cursor =
+		(info->fw_version == 0x020022 || info->fw_version == 0x020600);
+
+	if (info->hw_version > 1) {
+		/* For now show extra debug information */
+		info->debug = 1;
+
+		if (info->fw_version >= 0x020800)
+			info->reports_pressure = true;
+	}
+
+	/*
+	 * The signatures of v3 and v4 packets change depending on the
+	 * value of this hardware flag.
+	 */
+	info->crc_enabled = (info->fw_version & 0x4000) == 0x4000 ||
+			     dmi_check_system(elantech_dmi_force_crc_enabled);
+
+	/* Enable real hardware resolution on hw_version 3 ? */
+	info->set_hw_resolution = !dmi_check_system(no_hw_res_dmi_table);
+
+	return 0;
+}
+
+static int elantech_query_info(struct psmouse *psmouse,
+			       struct elantech_device_info *info)
+{
+	unsigned char param[3];
+	unsigned char traces;
+	unsigned char ic_body[3];
+
+	memset(info, 0, sizeof(*info));
+
+	/*
+	 * Do the version query again so we can store the result
+	 */
+	if (synaptics_send_cmd(psmouse, ETP_FW_VERSION_QUERY, param)) {
+		psmouse_err(psmouse, "failed to query firmware version.\n");
+		return -EINVAL;
+	}
+	info->fw_version = (param[0] << 16) | (param[1] << 8) | param[2];
+
+	if (elantech_set_properties(info)) {
+		psmouse_err(psmouse, "unknown hardware version, aborting...\n");
+		return -EINVAL;
+	}
+	psmouse_info(psmouse,
+		     "assuming hardware version %d (with firmware version 0x%02x%02x%02x)\n",
+		     info->hw_version, param[0], param[1], param[2]);
+
+	if (info->send_cmd(psmouse, ETP_CAPABILITIES_QUERY,
+	    info->capabilities)) {
+		psmouse_err(psmouse, "failed to query capabilities.\n");
+		return -EINVAL;
+	}
+	psmouse_info(psmouse,
+		     "Synaptics capabilities query result 0x%02x, 0x%02x, 0x%02x.\n",
+		     info->capabilities[0], info->capabilities[1],
+		     info->capabilities[2]);
+
+	if (info->hw_version != 1) {
+		if (info->send_cmd(psmouse, ETP_SAMPLE_QUERY, info->samples)) {
+			psmouse_err(psmouse, "failed to query sample data\n");
+			return -EINVAL;
+		}
+		psmouse_info(psmouse,
+			     "Elan sample query result %02x, %02x, %02x\n",
+			     info->samples[0],
+			     info->samples[1],
+			     info->samples[2]);
+	}
+
+	if (info->pattern > 0x00 && info->ic_version == 0xf) {
+		if (info->send_cmd(psmouse, ETP_ICBODY_QUERY, ic_body)) {
+			psmouse_err(psmouse, "failed to query ic body\n");
+			return -EINVAL;
+		}
+		info->ic_version = be16_to_cpup((__be16 *)ic_body);
+		psmouse_info(psmouse,
+			     "Elan ic body: %#04x, current fw version: %#02x\n",
+			     info->ic_version, ic_body[2]);
+	}
+
+	info->product_id = be16_to_cpup((__be16 *)info->samples);
+	if (info->pattern == 0x00)
+		info->product_id &= 0xff;
+
+	if (info->samples[1] == 0x74 && info->hw_version == 0x03) {
+		/*
+		 * This module has a bug which makes absolute mode
+		 * unusable, so let's abort so we'll be using standard
+		 * PS/2 protocol.
+		 */
+		psmouse_info(psmouse,
+			     "absolute mode broken, forcing standard PS/2 protocol\n");
+		return -ENODEV;
+	}
+
+	/* The MSB indicates the presence of the trackpoint */
+	info->has_trackpoint = (info->capabilities[0] & 0x80) == 0x80;
+
+	if (info->has_trackpoint && info->ic_version == 0x0011 &&
+	    (info->product_id == 0x08 || info->product_id == 0x09 ||
+	     info->product_id == 0x0d || info->product_id == 0x0e)) {
+		/*
+		 * This module has a bug which makes trackpoint in SMBus
+		 * mode return invalid data unless trackpoint is switched
+		 * from using 0x5e reports to 0x5f. If we are not able to
+		 * make the switch, let's abort initialization so we'll be
+		 * using standard PS/2 protocol.
+		 */
+		if (elantech_change_report_id(psmouse)) {
+			psmouse_info(psmouse,
+				     "Trackpoint report is broken, forcing standard PS/2 protocol\n");
+			return -ENODEV;
+		}
+	}
+
+	info->x_res = 31;
+	info->y_res = 31;
+	if (info->hw_version == 4) {
+		if (elantech_get_resolution_v4(psmouse,
+					       &info->x_res,
+					       &info->y_res,
+					       &info->bus)) {
+			psmouse_warn(psmouse,
+				     "failed to query resolution data.\n");
+		}
+	}
+
+	/* query range information */
+	switch (info->hw_version) {
+	case 1:
+		info->x_min = ETP_XMIN_V1;
+		info->y_min = ETP_YMIN_V1;
+		info->x_max = ETP_XMAX_V1;
+		info->y_max = ETP_YMAX_V1;
+		break;
+
+	case 2:
+		if (info->fw_version == 0x020800 ||
+		    info->fw_version == 0x020b00 ||
+		    info->fw_version == 0x020030) {
+			info->x_min = ETP_XMIN_V2;
+			info->y_min = ETP_YMIN_V2;
+			info->x_max = ETP_XMAX_V2;
+			info->y_max = ETP_YMAX_V2;
+		} else {
+			int i;
+			int fixed_dpi;
+
+			i = (info->fw_version > 0x020800 &&
+			     info->fw_version < 0x020900) ? 1 : 2;
+
+			if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
+				return -EINVAL;
+
+			fixed_dpi = param[1] & 0x10;
+
+			if (((info->fw_version >> 16) == 0x14) && fixed_dpi) {
+				if (info->send_cmd(psmouse, ETP_SAMPLE_QUERY, param))
+					return -EINVAL;
+
+				info->x_max = (info->capabilities[1] - i) * param[1] / 2;
+				info->y_max = (info->capabilities[2] - i) * param[2] / 2;
+			} else if (info->fw_version == 0x040216) {
+				info->x_max = 819;
+				info->y_max = 405;
+			} else if (info->fw_version == 0x040219 || info->fw_version == 0x040215) {
+				info->x_max = 900;
+				info->y_max = 500;
+			} else {
+				info->x_max = (info->capabilities[1] - i) * 64;
+				info->y_max = (info->capabilities[2] - i) * 64;
+			}
+		}
+		break;
+
+	case 3:
+		if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
+			return -EINVAL;
+
+		info->x_max = (0x0f & param[0]) << 8 | param[1];
+		info->y_max = (0xf0 & param[0]) << 4 | param[2];
+		break;
+
+	case 4:
+		if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
+			return -EINVAL;
+
+		info->x_max = (0x0f & param[0]) << 8 | param[1];
+		info->y_max = (0xf0 & param[0]) << 4 | param[2];
+		traces = info->capabilities[1];
+		if ((traces < 2) || (traces > info->x_max))
+			return -EINVAL;
+
+		info->width = info->x_max / (traces - 1);
+
+		/* column number of traces */
+		info->x_traces = traces;
+
+		/* row number of traces */
+		traces = info->capabilities[2];
+		if ((traces >= 2) && (traces <= info->y_max))
+			info->y_traces = traces;
+
+		break;
+	}
+
+	/* check for the middle button: DMI matching or new v4 firmwares */
+	info->has_middle_button = dmi_check_system(elantech_dmi_has_middle_button) ||
+				  (ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version) &&
+				   !elantech_is_buttonpad(info));
+
+	return 0;
+}
+
+#if defined(CONFIG_MOUSE_PS2_ELANTECH_SMBUS)
+
+/*
+ * The newest Elantech device can use a secondary bus (over SMBus) which
+ * provides a better bandwidth and allow a better control of the touchpads.
+ * This is used to decide if we need to use this bus or not.
+ */
+enum {
+	ELANTECH_SMBUS_NOT_SET = -1,
+	ELANTECH_SMBUS_OFF,
+	ELANTECH_SMBUS_ON,
+};
+
+static int elantech_smbus = IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_SMBUS) ?
+		ELANTECH_SMBUS_NOT_SET : ELANTECH_SMBUS_OFF;
+module_param_named(elantech_smbus, elantech_smbus, int, 0644);
+MODULE_PARM_DESC(elantech_smbus, "Use a secondary bus for the Elantech device.");
+
+static const char * const i2c_blacklist_pnp_ids[] = {
+	/*
+	 * These are known to not be working properly as bits are missing
+	 * in elan_i2c.
+	 */
+	NULL
+};
+
+static int elantech_create_smbus(struct psmouse *psmouse,
+				 struct elantech_device_info *info,
+				 bool leave_breadcrumbs)
+{
+	struct property_entry i2c_props[11] = {};
+	struct i2c_board_info smbus_board = {
+		I2C_BOARD_INFO("elan_i2c", 0x15),
+		.flags = I2C_CLIENT_HOST_NOTIFY,
+	};
+	unsigned int idx = 0;
+
+	smbus_board.properties = i2c_props;
+
+	i2c_props[idx++] = PROPERTY_ENTRY_U32("touchscreen-size-x",
+						   info->x_max + 1);
+	i2c_props[idx++] = PROPERTY_ENTRY_U32("touchscreen-size-y",
+						   info->y_max + 1);
+	i2c_props[idx++] = PROPERTY_ENTRY_U32("touchscreen-min-x",
+						   info->x_min);
+	i2c_props[idx++] = PROPERTY_ENTRY_U32("touchscreen-min-y",
+						   info->y_min);
+	if (info->x_res)
+		i2c_props[idx++] = PROPERTY_ENTRY_U32("touchscreen-x-mm",
+						      (info->x_max + 1) / info->x_res);
+	if (info->y_res)
+		i2c_props[idx++] = PROPERTY_ENTRY_U32("touchscreen-y-mm",
+						      (info->y_max + 1) / info->y_res);
+
+	if (info->has_trackpoint)
+		i2c_props[idx++] = PROPERTY_ENTRY_BOOL("elan,trackpoint");
+
+	if (info->has_middle_button)
+		i2c_props[idx++] = PROPERTY_ENTRY_BOOL("elan,middle-button");
+
+	if (info->x_traces)
+		i2c_props[idx++] = PROPERTY_ENTRY_U32("elan,x_traces",
+						      info->x_traces);
+	if (info->y_traces)
+		i2c_props[idx++] = PROPERTY_ENTRY_U32("elan,y_traces",
+						      info->y_traces);
+
+	if (elantech_is_buttonpad(info))
+		i2c_props[idx++] = PROPERTY_ENTRY_BOOL("elan,clickpad");
+
+	return psmouse_smbus_init(psmouse, &smbus_board, NULL, 0, false,
+				  leave_breadcrumbs);
+}
+
+/**
+ * elantech_setup_smbus - called once the PS/2 devices are enumerated
+ * and decides to instantiate a SMBus InterTouch device.
+ */
+static int elantech_setup_smbus(struct psmouse *psmouse,
+				struct elantech_device_info *info,
+				bool leave_breadcrumbs)
+{
+	int error;
+
+	if (elantech_smbus == ELANTECH_SMBUS_OFF)
+		return -ENXIO;
+
+	if (elantech_smbus == ELANTECH_SMBUS_NOT_SET) {
+		/*
+		 * New ICs are enabled by default, unless mentioned in
+		 * i2c_blacklist_pnp_ids.
+		 * Old ICs are up to the user to decide.
+		 */
+		if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version) ||
+		    psmouse_matches_pnp_id(psmouse, i2c_blacklist_pnp_ids))
+			return -ENXIO;
+	}
+
+	psmouse_info(psmouse, "Trying to set up SMBus access\n");
+
+	error = elantech_create_smbus(psmouse, info, leave_breadcrumbs);
+	if (error) {
+		if (error == -EAGAIN)
+			psmouse_info(psmouse, "SMbus companion is not ready yet\n");
+		else
+			psmouse_err(psmouse, "unable to create intertouch device\n");
+
+		return error;
+	}
+
+	return 0;
+}
+
+static bool elantech_use_host_notify(struct psmouse *psmouse,
+				     struct elantech_device_info *info)
+{
+	if (ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
+		return true;
+
+	switch (info->bus) {
+	case ETP_BUS_PS2_ONLY:
+		/* expected case */
+		break;
+	case ETP_BUS_SMB_ALERT_ONLY:
+	case ETP_BUS_PS2_SMB_ALERT:
+		psmouse_dbg(psmouse, "Ignoring SMBus provider through alert protocol.\n");
+		break;
+	case ETP_BUS_SMB_HST_NTFY_ONLY:
+	case ETP_BUS_PS2_SMB_HST_NTFY:
+		return true;
+	default:
+		psmouse_dbg(psmouse,
+			    "Ignoring SMBus bus provider %d.\n",
+			    info->bus);
+	}
+
+	return false;
+}
+
+int elantech_init_smbus(struct psmouse *psmouse)
+{
+	struct elantech_device_info info;
+	int error;
+
+	psmouse_reset(psmouse);
+
+	error = elantech_query_info(psmouse, &info);
+	if (error)
+		goto init_fail;
+
+	if (info.hw_version < 4) {
+		error = -ENXIO;
+		goto init_fail;
+	}
+
+	return elantech_create_smbus(psmouse, &info, false);
+ init_fail:
+	psmouse_reset(psmouse);
+	return error;
+}
+#endif /* CONFIG_MOUSE_PS2_ELANTECH_SMBUS */
+
+/*
+ * Initialize the touchpad and create sysfs entries
+ */
+static int elantech_setup_ps2(struct psmouse *psmouse,
+			      struct elantech_device_info *info)
+{
+	struct elantech_data *etd;
+	int i;
+	int error = -EINVAL;
+	struct input_dev *tp_dev;
+
+	psmouse->private = etd = kzalloc(sizeof(*etd), GFP_KERNEL);
+	if (!etd)
+		return -ENOMEM;
+
+	etd->info = *info;
+
+	etd->parity[0] = 1;
+	for (i = 1; i < 256; i++)
+		etd->parity[i] = etd->parity[i & (i - 1)] ^ 1;
+
+	if (elantech_set_absolute_mode(psmouse)) {
+		psmouse_err(psmouse,
+			    "failed to put touchpad into absolute mode.\n");
+		goto init_fail;
+	}
+
+	if (info->fw_version == 0x381f17) {
+		etd->original_set_rate = psmouse->set_rate;
+		psmouse->set_rate = elantech_set_rate_restore_reg_07;
+	}
+
+	if (elantech_set_input_params(psmouse)) {
+		psmouse_err(psmouse, "failed to query touchpad range.\n");
+		goto init_fail;
+	}
+
+	error = sysfs_create_group(&psmouse->ps2dev.serio->dev.kobj,
+				   &elantech_attr_group);
+	if (error) {
+		psmouse_err(psmouse,
+			    "failed to create sysfs attributes, error: %d.\n",
+			    error);
+		goto init_fail;
+	}
+
+	if (info->has_trackpoint) {
+		tp_dev = input_allocate_device();
+
+		if (!tp_dev) {
+			error = -ENOMEM;
+			goto init_fail_tp_alloc;
+		}
+
+		etd->tp_dev = tp_dev;
+		snprintf(etd->tp_phys, sizeof(etd->tp_phys), "%s/input1",
+			psmouse->ps2dev.serio->phys);
+		tp_dev->phys = etd->tp_phys;
+		tp_dev->name = "ETPS/2 Elantech TrackPoint";
+		tp_dev->id.bustype = BUS_I8042;
+		tp_dev->id.vendor  = 0x0002;
+		tp_dev->id.product = PSMOUSE_ELANTECH;
+		tp_dev->id.version = 0x0000;
+		tp_dev->dev.parent = &psmouse->ps2dev.serio->dev;
+		tp_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
+		tp_dev->relbit[BIT_WORD(REL_X)] =
+			BIT_MASK(REL_X) | BIT_MASK(REL_Y);
+		tp_dev->keybit[BIT_WORD(BTN_LEFT)] =
+			BIT_MASK(BTN_LEFT) | BIT_MASK(BTN_MIDDLE) |
+			BIT_MASK(BTN_RIGHT);
+
+		__set_bit(INPUT_PROP_POINTER, tp_dev->propbit);
+		__set_bit(INPUT_PROP_POINTING_STICK, tp_dev->propbit);
+
+		error = input_register_device(etd->tp_dev);
+		if (error < 0)
+			goto init_fail_tp_reg;
+	}
+
+	psmouse->protocol_handler = elantech_process_byte;
+	psmouse->disconnect = elantech_disconnect;
+	psmouse->reconnect = elantech_reconnect;
+	psmouse->fast_reconnect = NULL;
+	psmouse->pktsize = info->hw_version > 1 ? 6 : 4;
+
+	return 0;
+ init_fail_tp_reg:
+	input_free_device(tp_dev);
+ init_fail_tp_alloc:
+	sysfs_remove_group(&psmouse->ps2dev.serio->dev.kobj,
+			   &elantech_attr_group);
+ init_fail:
+	kfree(etd);
+	return error;
+}
+
+int elantech_init_ps2(struct psmouse *psmouse)
+{
+	struct elantech_device_info info;
+	int error;
+
+	psmouse_reset(psmouse);
+
+	error = elantech_query_info(psmouse, &info);
+	if (error)
+		goto init_fail;
+
+	error = elantech_setup_ps2(psmouse, &info);
+	if (error)
+		goto init_fail;
+
+	return 0;
+ init_fail:
+	psmouse_reset(psmouse);
+	return error;
+}
+
+int elantech_init(struct psmouse *psmouse)
+{
+	struct elantech_device_info info;
+	int error;
+
+	psmouse_reset(psmouse);
+
+	error = elantech_query_info(psmouse, &info);
+	if (error)
+		goto init_fail;
+
+#if defined(CONFIG_MOUSE_PS2_ELANTECH_SMBUS)
+
+	if (elantech_use_host_notify(psmouse, &info)) {
+		if (!IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_SMBUS) ||
+		    !IS_ENABLED(CONFIG_MOUSE_PS2_ELANTECH_SMBUS)) {
+			psmouse_warn(psmouse,
+				     "The touchpad can support a better bus than the too old PS/2 protocol. "
+				     "Make sure MOUSE_PS2_ELANTECH_SMBUS and MOUSE_ELAN_I2C_SMBUS are enabled to get a better touchpad experience.\n");
+		}
+		error = elantech_setup_smbus(psmouse, &info, true);
+		if (!error)
+			return PSMOUSE_ELANTECH_SMBUS;
+	}
+
+#endif /* CONFIG_MOUSE_PS2_ELANTECH_SMBUS */
+
+	error = elantech_setup_ps2(psmouse, &info);
+	if (error < 0) {
+		/*
+		 * Not using any flavor of Elantech support, so clean up
+		 * SMbus breadcrumbs, if any.
+		 */
+		psmouse_smbus_cleanup(psmouse);
+		goto init_fail;
+	}
+
+	return PSMOUSE_ELANTECH;
+ init_fail:
+	psmouse_reset(psmouse);
+	return error;
+}