[PATCH v3] HID: Wiimote: Treat the d-pad as an analogue stick

The controllers from the Super Nintendo Classic Edition (AKA the SNES
Mini) appear as a Classic Controller Pro when connected to a Wii
Remote. All the buttons work as the same, with the d-pad being mapped
the same as the d-pad on the Classic Controller Pro. This differs from
the behaviour of most controllers with d-pads and no analogue sticks,
where the d-pad maps to ABS_HAT1X for left and right, and ABS_HAT1Y
for up and down. This patch adds an option to the hid-wiimote module
to make the Super Nintendo Classic Controller behave this way.

The patch has been tested with a Super Nintendo Classic Controller
plugged into a Wii Remote in both with the option both enabled and
disabled. When enabled the d-pad acts as the analogue control, and
when disabled it acts as it did before the patch was applied. This
patch has not been tested with e Wii Classic Controller (either the
original or the pro version) as I do not have one of these
controllers.

Although I have not tested it with these controllers, I think it is
likely this patch will also work with the NES Classic Edition
Controllers.

Changes from V1 to V2
* 3 if statements to control the behaviour, one to make the d-pad
register as button presses when the behaviour is disabled, and 2 to
make it act as an analog stick when enabled (once for each of the
motion plus states)
* the values for lx and ly are calculated and then passed to
input_report_abs() in one place, rather then calling
input_report_abs() from different places depending on how the values
are determined.
* using an array to map from button presses to analog value.
* reduced the values used to indicate the position of the analog stick

Changes from V3 to V3
* Moved the definition of dpad_as_analog in hid-wiimote.h
* Renamed the dpad_as_analog vaiable to wiimote_dpad_as_analog
* changed digital_to_analog from an __s8 to static const s8
* Removed the unnecessary braces when getting values from digital_to_analog

Note: I have also attached a patch file to this final version in
addition to the code in the body because gmail web client keeps
turning the tabs into spaces.

Signed-off-by: Daniel G. Morse <redacted>
Reviewed-by: David Rheinsberg <redacted>

From 8909feec10fda919d1ec46c95418d63ac52ee41f Mon Sep 17 00:00:00 2001
From: Speedfox <redacted>
Date: Tue, 26 May 2020 02:55:50 +0100
Subject: [PATCH] Added option to make d-pad analog

Updates from code review
---
 drivers/hid/hid-wiimote-core.c    |  5 +++
 drivers/hid/hid-wiimote-modules.c | 67 ++++++++++++++++++++-----------
 drivers/hid/hid-wiimote.h         |  2 +
 3 files changed, 50 insertions(+), 24 deletions(-)

diff --git a/drivers/hid/hid-wiimote-core.c b/drivers/hid/hid-wiimote-core.c
index 92874dbe4d4a..679e142fc850 100644
--- a/drivers/hid/hid-wiimote-core.c
+++ b/drivers/hid/hid-wiimote-core.c

@@ -1870,6 +1870,11 @@ static const struct hid_device_id

wiimote_hid_devices[] = {
                 USB_DEVICE_ID_NINTENDO_WIIMOTE2) },
     { }
 };
+
+bool wiimote_dpad_as_analog = false;
+module_param_named(dpad_as_analog, wiimote_dpad_as_analog, bool, 0644);
+MODULE_PARM_DESC(dpad_as_analog, "Use D-Pad as main analog input");
+
 MODULE_DEVICE_TABLE(hid, wiimote_hid_devices);

 static struct hid_driver wiimote_hid_driver = {

diff --git a/drivers/hid/hid-wiimote-modules.c

b/drivers/hid/hid-wiimote-modules.c
index 2c3925357857..213c58bf2495 100644

--- a/drivers/hid/hid-wiimote-modules.c
+++ b/drivers/hid/hid-wiimote-modules.c

@@ -1088,12 +1088,28 @@ static void wiimod_classic_in_ext(struct

wiimote_data *wdata, const __u8 *ext)
      * is the same as before.
      */

+    static const s8 digital_to_analog[3] = {0x20, 0, -0x20};
+
     if (wdata->state.flags & WIIPROTO_FLAG_MP_ACTIVE) {
-        lx = ext[0] & 0x3e;
-        ly = ext[1] & 0x3e;
+        if (wiimote_dpad_as_analog) {
+            lx = digital_to_analog[1 - !(ext[4] & 0x80)
+                + !(ext[1] & 0x01)];
+            ly = digital_to_analog[1 - !(ext[4] & 0x40)
+                + !(ext[0] & 0x01)];
+        } else {
+            lx = (ext[0] & 0x3e) - 0x20;
+            ly = (ext[1] & 0x3e) - 0x20;
+        }
     } else {
-        lx = ext[0] & 0x3f;
-        ly = ext[1] & 0x3f;
+        if (wiimote_dpad_as_analog) {
+            lx = digital_to_analog[1 - !(ext[4] & 0x80)
+                + !(ext[5] & 0x02)];
+            ly = digital_to_analog[1 - !(ext[4] & 0x40)
+                + !(ext[5] & 0x01)];
+        } else {
+            lx = (ext[0] & 0x3f) - 0x20;
+            ly = (ext[1] & 0x3f) - 0x20;
+        }
     }

     rx = (ext[0] >> 3) & 0x18;

@@ -1110,19 +1126,13 @@ static void wiimod_classic_in_ext(struct

wiimote_data *wdata, const __u8 *ext)
     rt <<= 1;
     lt <<= 1;

-    input_report_abs(wdata->extension.input, ABS_HAT1X, lx - 0x20);
-    input_report_abs(wdata->extension.input, ABS_HAT1Y, ly - 0x20);
+    input_report_abs(wdata->extension.input, ABS_HAT1X, lx);
+    input_report_abs(wdata->extension.input, ABS_HAT1Y, ly);
     input_report_abs(wdata->extension.input, ABS_HAT2X, rx - 0x20);
     input_report_abs(wdata->extension.input, ABS_HAT2Y, ry - 0x20);
     input_report_abs(wdata->extension.input, ABS_HAT3X, rt);
     input_report_abs(wdata->extension.input, ABS_HAT3Y, lt);

-    input_report_key(wdata->extension.input,
-             wiimod_classic_map[WIIMOD_CLASSIC_KEY_RIGHT],
-             !(ext[4] & 0x80));
-    input_report_key(wdata->extension.input,
-             wiimod_classic_map[WIIMOD_CLASSIC_KEY_DOWN],
-             !(ext[4] & 0x40));
     input_report_key(wdata->extension.input,
              wiimod_classic_map[WIIMOD_CLASSIC_KEY_LT],
              !(ext[4] & 0x20));

@@ -1157,20 +1167,29 @@ static void wiimod_classic_in_ext(struct

wiimote_data *wdata, const __u8 *ext)
              wiimod_classic_map[WIIMOD_CLASSIC_KEY_ZR],
              !(ext[5] & 0x04));

-    if (wdata->state.flags & WIIPROTO_FLAG_MP_ACTIVE) {
-        input_report_key(wdata->extension.input,
-             wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
-             !(ext[1] & 0x01));
-        input_report_key(wdata->extension.input,
-             wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
-             !(ext[0] & 0x01));
-    } else {
+    if (!wiimote_dpad_as_analog) {
         input_report_key(wdata->extension.input,
-             wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
-             !(ext[5] & 0x02));
+                 wiimod_classic_map[WIIMOD_CLASSIC_KEY_RIGHT],
+                 !(ext[4] & 0x80));
         input_report_key(wdata->extension.input,
-             wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
-             !(ext[5] & 0x01));
+                 wiimod_classic_map[WIIMOD_CLASSIC_KEY_DOWN],
+                 !(ext[4] & 0x40));
+
+        if (wdata->state.flags & WIIPROTO_FLAG_MP_ACTIVE) {
+            input_report_key(wdata->extension.input,
+                 wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
+                 !(ext[1] & 0x01));
+            input_report_key(wdata->extension.input,
+                 wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
+                 !(ext[0] & 0x01));
+        } else {
+            input_report_key(wdata->extension.input,
+                 wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
+                 !(ext[5] & 0x02));
+            input_report_key(wdata->extension.input,
+                 wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
+                 !(ext[5] & 0x01));
+        }
     }

     input_sync(wdata->extension.input);

diff --git a/drivers/hid/hid-wiimote.h b/drivers/hid/hid-wiimote.h
index b2a26a0a8f12..ad4ff837f43e 100644
--- a/drivers/hid/hid-wiimote.h
+++ b/drivers/hid/hid-wiimote.h

@@ -162,6 +162,8 @@ struct wiimote_data {
     struct work_struct init_worker;
 };

+extern bool wiimote_dpad_as_analog;
+
 /* wiimote modules */

 enum wiimod_module {

-- 
2.25.1