[PATCH v8 1/3] rust: helpers: add SPI helpers

[Shuai Liu <847807867@qq.com>]

Add C helpers for the SPI functions that are `static inline` in C and
therefore cannot be accessed from Rust directly: spi_unregister_driver(),
spi_write() and spi_read().

The helpers are guarded by CONFIG_SPI, since the SPI core functions they
call are not available when SPI support is disabled.

Also include <linux/spi/spi.h> in the bindgen bindings helper, so that
the Rust side can access the SPI data types.

Signed-off-by: Shuai Liu <847807867@qq.com>
---
 rust/bindings/bindings_helper.h |  1 +
 rust/helpers/helpers.c          |  1 +
 rust/helpers/spi.c              | 26 ++++++++++++++++++++++++++
 3 files changed, 28 insertions(+)
 create mode 100644 rust/helpers/spi.c

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index cc41dc9467577..faa4149682fc2 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -89,6 +89,7 @@
 #include <linux/security.h>
 #include <linux/serdev.h>
 #include <linux/slab.h>
+#include <linux/spi/spi.h>
 #include <linux/sys_soc.h>
 #include <linux/task_work.h>
 #include <linux/tracepoint.h>
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 787dd8ff8c6c8..0f854e051415a 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -96,6 +96,7 @@
 #include "serdev.c"
 #include "signal.c"
 #include "slab.c"
+#include "spi.c"
 #include "spinlock.c"
 #include "string.c"
 #include "srcu.c"
diff --git a/rust/helpers/spi.c b/rust/helpers/spi.c
new file mode 100644
index 0000000000000..179a90e014e04
--- /dev/null
+++ b/rust/helpers/spi.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/spi/spi.h>
+
+#ifdef CONFIG_SPI
+
+__rust_helper
+void rust_helper_spi_unregister_driver(struct spi_driver *sdrv)
+{
+	spi_unregister_driver(sdrv);
+}
+
+__rust_helper
+void rust_helper_spi_message_init(struct spi_message *msg)
+{
+	spi_message_init(msg);
+}
+
+__rust_helper
+void rust_helper_spi_message_add_tail(struct spi_transfer *t,
+				      struct spi_message *msg)
+{
+	spi_message_add_tail(t, msg);
+}
+
+#endif
-- 
2.43.0