LinuxLists.cc - [RFC PATCH v2 0/2] rust: crates in other kernel directories

2023-10-27 00:35:27

Subject: [RFC PATCH v2 0/2] rust: crates in other kernel directories

This RFC provides makes possible to have bindings for kernel subsystems
that are compiled as modules.

Previously, if you wanted to have Rust bindings for a subsystem, like
AMBA for example, you had to put it under `rust/kernel/` so it came
part of the `kernel` crate, but this came with many downsides. Namely
if you compiled said subsystem as a module you've a dependency on it
from `kernel`, which is linked directly on `vmlinux`.

So instead of overpopulating `kernel` with a gazillion modules that
throws you into dire straits you should rather have the bindings in the
same directory as the subsystem you want to bind with and link it to
it.

With this patch Rust sources can be compiled into libraries for them to
be consumed. These libraries are ar archives that follow the `.rlib`
structure, namely a libfoo.rlib thin archive with a foo.foo.o object
and a libfoo.rmeta rustc metadata as members. Such Rust crates get
their symbols exposed and the `bindings` crate is made available for
them.

Also included there's a sample usage of this in another patch, but it
is not meant to be merged as it remains as an example.

If you want to use a crate with your Rust module just add a `rust-libs`
variable in your Makefile with a value of the relative directory of
said crate plus its name, e.g.

# Link with the foo crate
rust-libs += ../path/to/foo

Martin Rodriguez Reboredo (2):
kbuild: Build Rust crates as libraries
samples: rust: Add USB sample bindings

.gitignore | 2 ++
Makefile | 4 +--
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 +++++++++++++++
scripts/Makefile.build | 49 ++++++++++++++++++++++++++++++---
scripts/Makefile.lib | 18 ++++++++++--
scripts/Makefile.modfinal | 7 ++++-
11 files changed, 128 insertions(+), 10 deletions(-)
create mode 100644 drivers/usb/core/usb.rs
create mode 100644 samples/rust/rust_usb_simple.rs

--
2.42.0

2023-10-27 00:35:41

by Martin Rodriguez Reboredo

[permalink] [raw]

Subject: [RFC PATCH v2 1/2] kbuild: Build Rust crates as libraries

Enables compiling Rust crates as dependencies of kernel modules. These
are also meant to be used as libraries for other parts of the kernel.

For these crates `bindings` is also exposed to them and they get their
symbols exported for them to be used by other code.

When a composite object depends on an `.rlib` file, which by the way is
a current ar archive, Kbuild will compile it from its base Rust source
and archive it.

This makes possible to have Rust bindings for a subsystem that is
compiled either built-in or as a module. They can also be made into
modules by themselves too.

Signed-off-by: Martin Rodriguez Reboredo <[email protected]>
---
v1 -> v2:
- Fixed kernel compilation.
- Added support for building crates as modules.

.gitignore | 2 ++
Makefile | 4 ++--
scripts/Makefile.build | 49 +++++++++++++++++++++++++++++++++++----
scripts/Makefile.lib | 18 +++++++++++---
scripts/Makefile.modfinal | 7 +++++-
5 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/.gitignore b/.gitignore
index 0bbae167bf93..8353b01e2915 100644
--- a/.gitignore
+++ b/.gitignore
@@ -38,6 +38,7 @@
*.o
*.o.*
*.patch
+*.rlib
*.rmeta
*.rpm
*.rsi
@@ -53,6 +54,7 @@
*.zst
Module.symvers
modules.order
+exports_*_generated.c

#
# Top-level generic files
diff --git a/Makefile b/Makefile
index 8a40530868ff..4113a5b93ddc 100644
--- a/Makefile
+++ b/Makefile
@@ -283,7 +283,7 @@ no-compiler-targets := $(no-dot-config-targets) install dtbs_install \
headers_install modules_install modules_sign kernelrelease image_name
no-sync-config-targets := $(no-dot-config-targets) %install modules_sign kernelrelease \
image_name
-single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.rsi %.s %.symtypes %/
+single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.rlib %.rsi %.s %.symtypes %/

config-build :=
mixed-build :=
@@ -1919,7 +1919,7 @@ $(clean-dirs):
clean: $(clean-dirs)
$(call cmd,rmfiles)
@find $(or $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
- \( -name '*.[aios]' -o -name '*.rsi' -o -name '*.ko' -o -name '.*.cmd' \
+ \( -name '*.[aios]' -o -name '*.rlib' -o -name '*.rsi' -o -name '*.ko' -o -name '.*.cmd' \
-o -name '*.ko.*' \
-o -name '*.dtb' -o -name '*.dtbo' \
-o -name '*.dtb.S' -o -name '*.dtbo.S' \
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index da37bfa97211..11045ddba1a9 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -20,6 +20,7 @@ always-m :=
targets :=
subdir-y :=
subdir-m :=
+rust-libs :=
EXTRA_AFLAGS :=
EXTRA_CFLAGS :=
EXTRA_CPPFLAGS :=
@@ -243,9 +244,13 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
$(call if_changed_rule,cc_o_c)
$(call cmd,force_checksrc)

+mod_objs = $(call real-search, $*.o, .o, -objs -y -m)
+exports_objs = $(foreach m, $(sort $(basename \
+ $(filter $(notdir $(rlib-m)), $(mod_objs)))), exports_$m_generated.o)
+
# To make this rule robust against "Argument list too long" error,
# ensure to add $(obj)/ prefix by a shell command.
-cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) | \
+cmd_mod = printf '%s\n' $(mod_objs) $(exports_objs) | \
$(AWK) '!x[$$0]++ { print("$(obj)/"$$0) }' > $@

$(obj)/%.mod: FORCE
@@ -274,7 +279,7 @@ rust_common_cmd = \
-Zcrate-attr='feature($(rust_allowed_features))' \
--extern alloc --extern kernel \
--crate-type rlib -L $(objtree)/rust/ \
- --crate-name $(basename $(notdir $@)) \
+ --crate-name $(basename $(notdir $<)) \
--out-dir $(dir $@) --emit=dep-info=$(depfile)

# `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
@@ -285,11 +290,42 @@ rust_common_cmd = \
# i.e. the outputs we would get for the different single targets (e.g. `.ll`)
# would not match each other.

+rlib_obj = $(dir $@)$*.$*.o
+rlib_meta = $(dir $@)$(patsubst %.rlib,%.rmeta,$(notdir $@))
+
quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<

+quiet_cmd_ln_rlib_o = SYMLINK $@
+ cmd_ln_rlib_o = ln -s -f $*.$*.o $@
+
$(obj)/%.o: $(src)/%.rs FORCE
- $(call if_changed_dep,rustc_o_rs)
+ $(if $(findstring $@, $(rlib-y) $(rlib-m)), \
+ $(call if_changed,ln_rlib_o), $(call if_changed_dep,rustc_o_rs))
+
+quiet_cmd_rustc_rlib_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
+ cmd_rustc_rlib_rs = $(rust_common_cmd) --extern bindings \
+ --emit=obj=$(rlib_obj) --emit=metadata=$(rlib_meta) $<; \
+ rm -f $@; $(AR) cDPrST $@ $(rlib_obj) $(rlib_meta)
+
+quiet_cmd_rlib_exports = EXPORTS $@
+ cmd_rlib_exports = \
+ echo "\#include <linux/module.h>" > $@; \
+ $(NM) -p --defined-only $(rlib_obj) \
+ | grep -P ' (T|R|D) (?!(init|cleanup)_module)' | cut -d ' ' -f 3 \
+ | xargs -Isymbol \
+ echo 'extern int symbol; EXPORT_SYMBOL_GPL(symbol);' >> $@
+
+$(rlib-m): $(obj)/%.o: $(obj)/exports_%_generated.o $(obj)/lib%.rlib $(src)/%.rs FORCE
+
+$(obj)/lib%.rlib: $(src)/%.rs FORCE
+ $(call if_changed_dep,rustc_rlib_rs)
+
+$(obj)/exports_%_generated.c: $(obj)/lib%.rlib FORCE
+ $(call if_changed,rlib_exports)
+
+$(obj)/exports_%_generated.o: $(obj)/exports_%_generated.c FORCE
+ $(call if_changed,cc_o_c)

quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
cmd_rustc_rsi_rs = \
@@ -394,9 +430,14 @@ $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
# To make this rule robust against "Argument list too long" error,
# remove $(obj)/ prefix, and restore it by a shell command.

+# If we have a .rlib for the archive change it for its object member
+crate-obj = $(foreach m, $1, $(if $(findstring .rlib, $m), \
+ $(basename $(m:lib%=%)).$(m:lib%.rlib=%.o),$m))
+
quiet_cmd_ar_builtin = AR $@
cmd_ar_builtin = rm -f $@; \
- $(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) | xargs) \
+ $(if $(real-prereqs), printf "$(obj)/%s " \
+ $(call crate-obj, $(patsubst $(obj)/%,%,$(real-prereqs))) | xargs) \
$(AR) cDPrST $@

$(obj)/built-in.a: $(real-obj-y) FORCE
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 68d0134bdbf9..3454b05dbbdc 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -45,12 +45,17 @@ else
obj-y := $(filter-out %/, $(obj-y))
endif

+rlib-y := $(foreach m, $(filter lib%.rlib, $(obj-y)), $(m:lib%.rlib=%.o))
+rlib-m := $(foreach m, $(filter lib%.rlib, $(obj-m)), $(m:lib%.rlib=%.o))
+
# Expand $(foo-objs) $(foo-y) etc. by replacing their individuals
suffix-search = $(strip $(foreach s, $3, $($(1:%$(strip $2)=%$s))))
# List composite targets that are constructed by combining other targets
multi-search = $(sort $(foreach m, $1, $(if $(call suffix-search, $m, $2, $3 -), $m)))
# List primitive targets that are compiled from source files
real-search = $(foreach m, $1, $(if $(call suffix-search, $m, $2, $3 -), $(call suffix-search, $m, $2, $3), $m))
+# List exported symbols from .rlib targets
+rlib-exports = $(foreach m, $1, $(if $(findstring .rlib, $m),$(m:lib%.rlib=exports_%_generated.o)) $m)

# If $(foo-objs), $(foo-y), $(foo-m), or $(foo-) exists, foo.o is a composite object
multi-obj-y := $(call multi-search, $(obj-y), .o, -objs -y)
@@ -59,7 +64,7 @@ multi-obj-ym := $(multi-obj-y) $(multi-obj-m)

# Replace multi-part objects by their individual parts,
# including built-in.a from subdirectories
-real-obj-y := $(call real-search, $(obj-y), .o, -objs -y)
+real-obj-y := $(call rlib-exports, $(call real-search, $(obj-y), .o, -objs -y))
real-obj-m := $(call real-search, $(obj-m), .o, -objs -y -m)

always-y += $(always-m)
@@ -95,6 +100,8 @@ extra-y := $(addprefix $(obj)/,$(extra-y))
always-y := $(addprefix $(obj)/,$(always-y))
targets := $(addprefix $(obj)/,$(targets))
obj-m := $(addprefix $(obj)/,$(obj-m))
+rlib-y := $(addprefix $(obj)/,$(rlib-y))
+rlib-m := $(addprefix $(obj)/,$(rlib-m))
lib-y := $(addprefix $(obj)/,$(lib-y))
real-obj-y := $(addprefix $(obj)/,$(real-obj-y))
real-obj-m := $(addprefix $(obj)/,$(real-obj-m))
@@ -210,7 +217,11 @@ _cpp_flags += -I $(srctree)/$(src) -I $(objtree)/$(obj)
endif
endif

-part-of-module = $(if $(filter $(basename $@).o, $(real-obj-m)),y)
+_rust_libs = $(foreach l, $(rust-libs), -L $(obj)/$(dir $l) --extern $(notdir $(basename $l)))
+
+part-of-module = \
+ $(if $(or $(filter $(basename $@).o, $(real-obj-m)), \
+ $(filter $(basename $@).rlib, $(real-obj-m))),y)
quiet_modtag = $(if $(part-of-module),[M], )

modkern_cflags = \
@@ -232,7 +243,8 @@ c_flags = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \
$(_c_flags) $(modkern_cflags) \
$(basename_flags) $(modname_flags)

-rust_flags = $(_rust_flags) $(modkern_rustflags) @$(objtree)/include/generated/rustc_cfg
+rust_flags = $(_rust_flags) $(modkern_rustflags) $(_rust_libs) \
+ @$(objtree)/include/generated/rustc_cfg

a_flags = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \
$(_a_flags) $(modkern_aflags)
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index b3a6aa8fbe8c..e05749a5ca0a 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -30,11 +30,16 @@ quiet_cmd_cc_o_c = CC [M] $@

ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)

+# Symlinks of foo.o that point to foo.foo.o are members of a .rlib archives,
+# so their exports should be added to the module
+ko_objs = $(foreach o, $(filter %.o, $^),$(if \
+ $(filter-out %$o,$(realpath $o)),$(dir $o)exports_$(notdir $*)_generated.o) $o)
+
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o += \
$(LD) -r $(KBUILD_LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
- -T scripts/module.lds -o $@ $(filter %.o, $^); \
+ -T scripts/module.lds -o $@ $(ko_objs); \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)

quiet_cmd_btf_ko = BTF [M] $@
--
2.42.0

2023-10-27 00:35:47

by Martin Rodriguez Reboredo

[permalink] [raw]

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

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 <[email protected]>
---
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

2023-10-27 03:21:23

by Martin Rodriguez Reboredo

[permalink] [raw]

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

This was missing in the patch, but you get the point...

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index c41eaab4ddb2..845cdd856981 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -10,6 +10,7 @@
#include <linux/errname.h>
#include <linux/slab.h>
#include <linux/refcount.h>
+#include <linux/usb.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/workqueue.h>

2023-10-27 07:17:25

by Greg Kroah-Hartman

[permalink] [raw]

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

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 <[email protected]>
> ---
> 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

2023-10-27 13:07:30

by Martin Rodriguez Reboredo

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

On 10/27/23 04:15, Greg Kroah-Hartman wrote:
> On Thu, Oct 26, 2023 at 09:34:51PM -0300, Martin Rodriguez Reboredo wrote:
>> [...]
>> +
>> +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 :)

Nice one! I'll probably target host APIs as of now due to what I have in
my hands.

>> + help
>> + Enables Rust bindings for USB.
>> [...]
>> +//! 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

No, you are right. Because Rust uses upper camel case for struct names
there's the tendency of lowering initialisms, so you can either leave it
as `USBSimple` or as `UsbSimple`. When I publish my USB host bindings
I'll take your comment into account for sure.

2023-10-27 13:08:35

by Greg Kroah-Hartman

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