Input: elantech - detect new ICs and setup Host Notify for them

New ICs are using a different scheme for the alternate bus parameter.
Given that they are new and are only using either PS2 only or PS2 + SMBus
Host Notify, we force those new ICs to use the SMBus solution for enhanced
reporting.

This allows the touchpad found on the Lenovo T480s to report 5 fingers
every 8 ms, instead of having a limit of 2 every 8 ms.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 510e7c0..07e40a5 100644 (file)
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -1793,11 +1793,11 @@ static int elantech_setup_smbus(struct psmouse *psmouse,
 
        if (elantech_smbus == ELANTECH_SMBUS_NOT_SET) {
                /*
-                * FIXME:
-                * constraint the I2C capable devices by using FW version,
-                * board version, or by using DMI matching
+                * New ICs are enabled by default.
+                * Old ICs are up to the user to decide.
                 */
-               return -ENXIO;
+               if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
+                       return -ENXIO;
        }
 
        psmouse_info(psmouse, "Trying to set up SMBus access\n");
@@ -1818,6 +1818,9 @@ static int elantech_setup_smbus(struct psmouse *psmouse,
 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 */

diff --git a/drivers/input/mouse/elantech.h b/drivers/input/mouse/elantech.h
index f9b1c48..1197270 100644 (file)
--- a/drivers/input/mouse/elantech.h
+++ b/drivers/input/mouse/elantech.h
@@ -116,6 +116,21 @@
 #define ETP_BUS_PS2_SMB_HST_NTFY       4
 
 /*
+ * New ICs are either using SMBus Host Notify or just plain PS2.
+ *
+ * ETP_FW_VERSION_QUERY is:
+ * Byte 1:
+ *  - bit 0..3: IC BODY
+ * Byte 2:
+ *  - bit 4: HiddenButton
+ *  - bit 5: PS2_SMBUS_NOTIFY
+ *  - bit 6: PS2CRCCheck
+ */
+#define ETP_NEW_IC_SMBUS_HOST_NOTIFY(fw_version)       \
+               ((((fw_version) & 0x0f2000) == 0x0f2000) && \
+                ((fw_version) & 0x0000ff) > 0)
+
+/*
  * The base position for one finger, v4 hardware
  */
 struct finger_pos {