rust: iomem: add readx/writex relaxed family of functions

This patch adds a set of functions for the `IoMem<T>` type
by reusing existing macros used for generating read/write
methods for that type. The handling of arch-specific cross-compilation
is done entirely on the C's side.

Signed-off-by: Maciej Falkowski <m.falkowski@samsung.com>

Author: Maciej Falkowski

rust/helpers.c

@@ -95,6 +95,57 @@ void rust_helper_writeq(u64 value, volatile void __iomem *addr)
 EXPORT_SYMBOL_GPL(rust_helper_writeq);
 #endif
 
+u8 rust_helper_readb_relaxed(const volatile void __iomem *addr)
+{
+	return readb_relaxed(addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_readb_relaxed);
+
+u16 rust_helper_readw_relaxed(const volatile void __iomem *addr)
+{
+	return readw_relaxed(addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_readw_relaxed);
+
+u32 rust_helper_readl_relaxed(const volatile void __iomem *addr)
+{
+	return readl_relaxed(addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_readl_relaxed);
+
+#ifdef CONFIG_64BIT
+u64 rust_helper_readq_relaxed(const volatile void __iomem *addr)
+{
+	return readq_relaxed(addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_readq_relaxed);
+#endif
+
+void rust_helper_writeb_relaxed(u8 value, volatile void __iomem *addr)
+{
+        writeb_relaxed(value, addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_writeb_relaxed);
+
+void rust_helper_writew_relaxed(u16 value, volatile void __iomem *addr)
+{
+        writew_relaxed(value, addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_writew_relaxed);
+
+void rust_helper_writel_relaxed(u32 value, volatile void __iomem *addr)
+{
+        writel_relaxed(value, addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_writel_relaxed);
+
+#ifdef CONFIG_64BIT
+void rust_helper_writeq_relaxed(u64 value, volatile void __iomem *addr)
+{
+        writeq_relaxed(value, addr);
+}
+EXPORT_SYMBOL_GPL(rust_helper_writeq_relaxed);
+#endif
 void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
 				  struct lock_class_key *key)
 {

rust/kernel/io_mem.rs

@@ -187,6 +187,16 @@ impl<const SIZE: usize> IoMem<SIZE> {
         u64
     );
 
+    define_read!(readb_relaxed, try_readb_relaxed, u8);
+    define_read!(readw_relaxed, try_readw_relaxed, u16);
+    define_read!(readl_relaxed, try_readl_relaxed, u32);
+    define_read!(
+        #[cfg(CONFIG_64BIT)]
+        readq_relaxed,
+        try_readq_relaxed,
+        u64
+    );
+
     define_write!(writeb, try_writeb, u8);
     define_write!(writew, try_writew, u16);
     define_write!(writel, try_writel, u32);
@@ -196,6 +206,16 @@ impl<const SIZE: usize> IoMem<SIZE> {
         try_writeq,
         u64
     );
+
+    define_write!(writeb_relaxed, try_writeb_relaxed, u8);
+    define_write!(writew_relaxed, try_writew_relaxed, u16);
+    define_write!(writel_relaxed, try_writel_relaxed, u32);
+    define_write!(
+        #[cfg(CONFIG_64BIT)]
+        writeq_relaxed,
+        try_writeq_relaxed,
+        u64
+    );
 }
 
 impl<const SIZE: usize> Drop for IoMem<SIZE> {