[RFC PATCH v2 2/2] samples: rust: Add USB sample bindings

[Martin Rodriguez Reboredo <yakoyoku@gmail.com>]

This is a demonstration of the capabilities of doing bindings with
subsystems that may or may not be statically linked.

Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
---
 drivers/usb/core/Kconfig        |  7 +++++++
 drivers/usb/core/Makefile       |  3 +++
 drivers/usb/core/usb.rs         | 13 +++++++++++++
 samples/rust/Kconfig            | 10 ++++++++++
 samples/rust/Makefile           |  3 +++
 samples/rust/rust_usb_simple.rs | 22 ++++++++++++++++++++++
 6 files changed, 58 insertions(+)
 create mode 100644 drivers/usb/core/usb.rs
 create mode 100644 samples/rust/rust_usb_simple.rs

diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index 351ede4b5de2..4b5604282129 100644
--- a/drivers/usb/core/Kconfig
+++ b/drivers/usb/core/Kconfig
@@ -116,3 +116,10 @@ config USB_AUTOSUSPEND_DELAY
 	  The default value Linux has always had is 2 seconds.  Change
 	  this value if you want a different delay and cannot modify
 	  the command line or module parameter.
+
+config USB_RUST
+	bool "Rust USB bindings"
+	depends on USB && RUST
+	default n
+	help
+	  Enables Rust bindings for USB.
diff --git a/drivers/usb/core/Makefile b/drivers/usb/core/Makefile
index 7d338e9c0657..00e116913591 100644
--- a/drivers/usb/core/Makefile
+++ b/drivers/usb/core/Makefile
@@ -11,6 +11,7 @@ usbcore-y += phy.o port.o
 usbcore-$(CONFIG_OF)		+= of.o
 usbcore-$(CONFIG_USB_PCI)		+= hcd-pci.o
 usbcore-$(CONFIG_ACPI)		+= usb-acpi.o
+usbcore-$(CONFIG_USB_RUST)		+= libusb.rlib
 
 ifdef CONFIG_USB_ONBOARD_HUB
 usbcore-y			+= ../misc/onboard_usb_hub_pdevs.o
@@ -18,4 +19,6 @@ endif
 
 obj-$(CONFIG_USB)		+= usbcore.o
 
+rust-libs			:= ./usb
+
 obj-$(CONFIG_USB_LEDS_TRIGGER_USBPORT)	+= ledtrig-usbport.o
diff --git a/drivers/usb/core/usb.rs b/drivers/usb/core/usb.rs
new file mode 100644
index 000000000000..3f7ad02153f5
--- /dev/null
+++ b/drivers/usb/core/usb.rs
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! USB devices and drivers.
+//!
+//! C header: [`include/linux/usb.h`](../../../../include/linux/usb.h)
+
+use kernel::bindings;
+
+/// Check if USB is disabled.
+pub fn disabled() -> bool {
+    // SAFETY: FFI call.
+    unsafe { bindings::usb_disabled() != 0 }
+}
diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index b0f74a81c8f9..12116f6fb526 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -30,6 +30,16 @@ config SAMPLE_RUST_PRINT
 
 	  If unsure, say N.
 
+config SAMPLE_RUST_USB_SIMPLE
+	tristate "USB simple device driver"
+	help
+	  This option builds the Rust USB simple driver sample.
+
+	  To compile this as a module, choose M here:
+	  the module will be called rust_usb_simple.
+
+	  If unsure, say N.
+
 config SAMPLE_RUST_HOSTPROGS
 	bool "Host programs"
 	help
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index 03086dabbea4..f1ab58a9ecdd 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -2,5 +2,8 @@
 
 obj-$(CONFIG_SAMPLE_RUST_MINIMAL)		+= rust_minimal.o
 obj-$(CONFIG_SAMPLE_RUST_PRINT)			+= rust_print.o
+obj-$(CONFIG_SAMPLE_RUST_USB_SIMPLE)		+= rust_usb_simple.o
+
+rust-libs					:= ../../drivers/usb/core/usb
 
 subdir-$(CONFIG_SAMPLE_RUST_HOSTPROGS)		+= hostprogs
diff --git a/samples/rust/rust_usb_simple.rs b/samples/rust/rust_usb_simple.rs
new file mode 100644
index 000000000000..3523f81d5eb8
--- /dev/null
+++ b/samples/rust/rust_usb_simple.rs
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust USB sample.
+
+use kernel::prelude::*;
+
+module! {
+    type: UsbSimple,
+    name: "rust_usb_simple",
+    author: "Martin Rodriguez Reboredo",
+    description: "Rust USB sample",
+    license: "GPL v2",
+}
+
+struct UsbSimple;
+
+impl kernel::Module for UsbSimple {
+    fn init(_module: &'static ThisModule) -> Result<Self> {
+        pr_info!("usb enabled: {}", !usb::disabled());
+        Ok(UsbSimple)
+    }
+}
-- 
2.42.0