[RFC PATCH v2 1/4] i2c: rust: add smbus_read_byte_data and smbus_read_word_data

[Muchamad Coirul Anwar <muchamadcoirulanwar@gmail.com>]

Signed-off-by: Muchamad Coirul Anwar <muchamadcoirulanwar@gmail.com>
---
 rust/kernel/i2c.rs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index 7b908f0c5a58..6eaea1158fda 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -477,6 +477,30 @@ impl<Ctx: device::DeviceContext> I2cClient<Ctx> {
     fn as_raw(&self) -> *mut bindings::i2c_client {
         self.0.get()
     }
+
+    /// Reads a single byte from a register via SMBus.
+    pub fn smbus_read_byte_data(&self, reg: u8) -> Result<u8> {
+        // SAFETY: `self.as_raw()` is a valid pointer to a `struct i2c_client`
+        // by the type invariant of `I2cClient`.
+        let ret = unsafe { bindings::i2c_smbus_read_byte_data(self.as_raw(), reg) };
+        if ret < 0 {
+            Err(Error::from_errno(ret))
+        } else {
+            Ok(ret as u8)
+        }
+    }
+
+    /// Reads a 16-bit word from a register via SMBus.
+    pub fn smbus_read_word_data(&self, reg: u8) -> Result<u16> {
+        // SAFETY: `self.as_raw()` is a valid pointer to a `struct i2c_client`
+        // by the type invariant of `I2cClient`.
+        let ret = unsafe { bindings::i2c_smbus_read_word_data(self.as_raw(), reg) };
+        if ret < 0 {
+            Err(Error::from_errno(ret))
+        } else {
+            Ok(ret as u16)
+        }
+    }
 }
 
 // SAFETY: `I2cClient` is a transparent wrapper of `struct i2c_client`.
-- 
2.50.0