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

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Oct 26, 2023 at 09:34:51PM -0300, Martin Rodriguez Reboredo wrote:
> 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

Nit, "n" is the default, this line is not needed.

Also, if you want to get really picky, _which_ USB is this for, the
"host" apis (you plug a USB device into a Linux maching), or the
"gadget" apis (i.e. Linux is running in the device that you plug into a
USB host)?  Linux supports both :)

> +	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;

"USBSimple" please.

> +
> +impl kernel::Module for UsbSimple {
> +    fn init(_module: &'static ThisModule) -> Result<Self> {
> +        pr_info!("usb enabled: {}", !usb::disabled());
> +        Ok(UsbSimple)
> +    }
> +}

I know this is just a fake patch to test the bindings logic, so sorry
for the noise, just wanted to get terminology right :)

thanks,

greg k-h