[PATCH v3 RESEND 3/3] rust: hid: Glorious PC Gaming Race Model O and O- mice reference driver

[Rahul Rameshbabu <sergeantsagara@protonmail.com>]

Demonstrate how to perform a report fixup from a Rust HID driver. The mice
specify the const flag incorrectly in the consumer input report descriptor,
which leads to inputs being ignored. Correctly patch the report descriptor
for the Model O and O- mice.

Portions of the HID report post-fixup:
device 0:0
...
0x81, 0x06,                    //  Input (Data,Var,Rel)               84
...
0x81, 0x06,                    //  Input (Data,Var,Rel)               112
...
0x81, 0x06,                    //  Input (Data,Var,Rel)               140

Signed-off-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>
---

Notes:
    Changelog:
    
        v2->v3:
          * Fixed docstring formatting
          * Updated MAINTAINERS file based on v1 and v2 discussion
        v1->v2:
          * Use vendor id and device id from drivers/hid/hid-ids.h bindings
          * Make use for dev_err! as appropriate

 MAINTAINERS                      |  7 ++++
 drivers/hid/Kconfig              |  8 +++++
 drivers/hid/Makefile             |  1 +
 drivers/hid/hid-glorious.c       |  2 ++
 drivers/hid/hid_glorious_rust.rs | 60 ++++++++++++++++++++++++++++++++
 5 files changed, 78 insertions(+)
 create mode 100644 drivers/hid/hid_glorious_rust.rs

diff --git a/MAINTAINERS b/MAINTAINERS
index 6c60765f2aaa..eee9a33914ef 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10200,6 +10200,13 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	drivers/platform/x86/gigabyte-wmi.c
 
+GLORIOUS RUST DRIVER [RUST]
+M:	Rahul Rameshbabu <sergeantsagara@protonmail.com>
+L:	linux-input@vger.kernel.org
+S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git rust
+F:	drivers/hid/hid_glorious_rust.rs
+
 GNSS SUBSYSTEM
 M:	Johan Hovold <johan@kernel.org>
 S:	Maintained
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 922e76e18af2..b8ef750fb8b6 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -406,6 +406,14 @@ config HID_GLORIOUS
 	  Support for Glorious PC Gaming Race mice such as
 	  the Glorious Model O, O- and D.
 
+config HID_GLORIOUS_RUST
+	tristate "Glorious O and O- mice Rust reference driver"
+	depends on USB_HID
+	depends on RUST_HID_ABSTRACTIONS
+	help
+	  Support for Glorious PC Gaming Race O and O- mice
+	  in Rust.
+
 config HID_HOLTEK
 	tristate "Holtek HID devices"
 	depends on USB_HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 10ae5dedbd84..bd86b3db5d88 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -55,6 +55,7 @@ obj-$(CONFIG_HID_FT260)		+= hid-ft260.o
 obj-$(CONFIG_HID_GEMBIRD)	+= hid-gembird.o
 obj-$(CONFIG_HID_GFRM)		+= hid-gfrm.o
 obj-$(CONFIG_HID_GLORIOUS)  += hid-glorious.o
+obj-$(CONFIG_HID_GLORIOUS_RUST)	+= hid_glorious_rust.o
 obj-$(CONFIG_HID_VIVALDI_COMMON) += hid-vivaldi-common.o
 obj-$(CONFIG_HID_GOODIX_SPI)	+= hid-goodix-spi.o
 obj-$(CONFIG_HID_GOOGLE_HAMMER)	+= hid-google-hammer.o
diff --git a/drivers/hid/hid-glorious.c b/drivers/hid/hid-glorious.c
index 5bbd81248053..d7362852c20f 100644
--- a/drivers/hid/hid-glorious.c
+++ b/drivers/hid/hid-glorious.c
@@ -76,8 +76,10 @@ static int glorious_probe(struct hid_device *hdev,
 }
 
 static const struct hid_device_id glorious_devices[] = {
+#if !IS_ENABLED(CONFIG_HID_GLORIOUS_RUST)
 	{ HID_USB_DEVICE(USB_VENDOR_ID_SINOWEALTH,
 		USB_DEVICE_ID_GLORIOUS_MODEL_O) },
+#endif
 	{ HID_USB_DEVICE(USB_VENDOR_ID_SINOWEALTH,
 		USB_DEVICE_ID_GLORIOUS_MODEL_D) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_LAVIEW,
diff --git a/drivers/hid/hid_glorious_rust.rs b/drivers/hid/hid_glorious_rust.rs
new file mode 100644
index 000000000000..8cffc1c605dd
--- /dev/null
+++ b/drivers/hid/hid_glorious_rust.rs
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2025 Rahul Rameshbabu <sergeantsagara@protonmail.com>
+
+//! Rust reference HID driver for Glorious Model O and O- mice.
+
+use kernel::{self, bindings, device, hid, prelude::*};
+
+struct GloriousRust;
+
+kernel::hid_device_table!(
+    HID_TABLE,
+    MODULE_HID_TABLE,
+    <GloriousRust as hid::Driver>::IdInfo,
+    [(
+        hid::DeviceId::new_usb(
+            hid::Group::Generic,
+            bindings::USB_VENDOR_ID_SINOWEALTH,
+            bindings::USB_DEVICE_ID_GLORIOUS_MODEL_O,
+        ),
+        (),
+    )]
+);
+
+#[vtable]
+impl hid::Driver for GloriousRust {
+    type IdInfo = ();
+    const ID_TABLE: hid::IdTable<Self::IdInfo> = &HID_TABLE;
+
+    /// Fix the Glorious Model O and O- consumer input report descriptor to use
+    /// the variable and relative flag, while clearing the const flag.
+    ///
+    /// Without this fixup, inputs from the mice will be ignored.
+    fn report_fixup<'a, 'b: 'a>(hdev: &hid::Device<device::Core>, rdesc: &'b mut [u8]) -> &'a [u8] {
+        if rdesc.len() == 213
+            && (rdesc[84] == 129 && rdesc[85] == 3)
+            && (rdesc[112] == 129 && rdesc[113] == 3)
+            && (rdesc[140] == 129 && rdesc[141] == 3)
+        {
+            dev_info!(
+                hdev.as_ref(),
+                "patching Glorious Model O consumer control report descriptor\n"
+            );
+
+            rdesc[85] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+            rdesc[113] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+            rdesc[141] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+        }
+
+        rdesc
+    }
+}
+
+kernel::module_hid_driver! {
+    type: GloriousRust,
+    name: "GloriousRust",
+    authors: ["Rahul Rameshbabu <sergeantsagara@protonmail.com>"],
+    description: "Rust reference HID driver for Glorious Model O and O- mice",
+    license: "GPL",
+}
-- 
2.47.2