i2c-v2: Support transfers with more than 255 bytes

1 files changed, 96 insertions, 89 deletions

diff --git a/embassy-stm32/src/i2c/v2.rs b/embassy-stm32/src/i2c/v2.rs
index 2f70d4263..b7aa84586 100644
--- a/embassy-stm32/src/i2c/v2.rs
+++ b/embassy-stm32/src/i2c/v2.rs
@@ -81,30 +81,40 @@ impl<'d, T: Instance> I2c<'d, T> {
         }
     }
 
-    fn master_read(&mut self, address: u8, length: usize, stop: Stop) {
+    fn master_read(&mut self, address: u8, length: usize, stop: Stop, reload: bool, restart: bool) {
         assert!(length < 256 && length > 0);
 
-        // Wait for any previous address sequence to end
-        // automatically. This could be up to 50% of a bus
-        // cycle (ie. up to 0.5/freq)
-        while unsafe { T::regs().cr2().read().start() == i2c::vals::Start::START } {}
+        if !restart {
+            // Wait for any previous address sequence to end
+            // automatically. This could be up to 50% of a bus
+            // cycle (ie. up to 0.5/freq)
+            while unsafe { T::regs().cr2().read().start() == i2c::vals::Start::START } {}
+        }
 
         // Set START and prepare to receive bytes into
         // `buffer`. The START bit can be set even if the bus
         // is BUSY or I2C is in slave mode.
 
+        let reload = if reload {
+            i2c::vals::Reload::NOTCOMPLETED
+        } else {
+            i2c::vals::Reload::COMPLETED
+        };
+
         unsafe {
             T::regs().cr2().modify(|w| {
                 w.set_sadd((address << 1 | 0) as u16);
+                w.set_add10(i2c::vals::Add::BIT7);
                 w.set_rd_wrn(i2c::vals::RdWrn::READ);
                 w.set_nbytes(length as u8);
                 w.set_start(i2c::vals::Start::START);
                 w.set_autoend(stop.autoend());
+                w.set_reload(reload);
             });
         }
     }
 
-    fn master_write(&mut self, address: u8, length: usize, stop: Stop) {
+    fn master_write(&mut self, address: u8, length: usize, stop: Stop, reload: bool) {
         assert!(length < 256 && length > 0);
 
         // Wait for any previous address sequence to end
@@ -112,6 +122,12 @@ impl<'d, T: Instance> I2c<'d, T> {
         // cycle (ie. up to 0.5/freq)
         while unsafe { T::regs().cr2().read().start() == i2c::vals::Start::START } {}
 
+        let reload = if reload {
+            i2c::vals::Reload::NOTCOMPLETED
+        } else {
+            i2c::vals::Reload::COMPLETED
+        };
+
         // Set START and prepare to send `bytes`. The
         // START bit can be set even if the bus is BUSY or
         // I2C is in slave mode.
@@ -123,21 +139,24 @@ impl<'d, T: Instance> I2c<'d, T> {
                 w.set_nbytes(length as u8);
                 w.set_start(i2c::vals::Start::START);
                 w.set_autoend(stop.autoend());
+                w.set_reload(reload);
             });
         }
     }
 
-    fn master_re_start(&mut self, address: u8, length: usize, stop: Stop) {
+    fn master_continue(&mut self, length: usize, reload: bool) {
         assert!(length < 256 && length > 0);
 
+        let reload = if reload {
+            i2c::vals::Reload::NOTCOMPLETED
+        } else {
+            i2c::vals::Reload::COMPLETED
+        };
+
         unsafe {
             T::regs().cr2().modify(|w| {
-                w.set_sadd((address << 1 | 1) as u16);
-                w.set_add10(i2c::vals::Add::BIT7);
-                w.set_rd_wrn(i2c::vals::RdWrn::READ);
                 w.set_nbytes(length as u8);
-                w.set_start(i2c::vals::Start::START);
-                w.set_autoend(stop.autoend());
+                w.set_reload(reload);
             });
         }
     }
@@ -224,66 +243,93 @@ impl<'d, T: Instance> I2c<'d, T> {
             }
         }
     }
-}
 
-impl<'d, T: Instance> Read for I2c<'d, T> {
-    type Error = Error;
+    fn read(&mut self, address: u8, buffer: &mut [u8], restart: bool) -> Result<(), Error> {
+        let last_chunk = (buffer.len() / 255).saturating_sub(1);
 
-    fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Self::Error> {
-        assert!(buffer.len() < 256 && buffer.len() > 0);
+        self.master_read(
+            address,
+            buffer.len().min(255),
+            Stop::Automatic,
+            last_chunk != 0,
+            restart,
+        );
 
-        self.master_read(address, buffer.len(), Stop::Automatic);
+        for (number, chunk) in buffer.chunks_mut(255).enumerate() {
+            if number != 0 {
+                self.master_continue(chunk.len(), number != last_chunk);
+            }
 
-        for byte in buffer {
-            // Wait until we have received something
-            self.wait_rxne()?;
+            for byte in chunk {
+                // Wait until we have received something
+                self.wait_rxne()?;
 
-            //*byte = self.i2c.rxdr.read().rxdata().bits();
-            unsafe {
-                *byte = T::regs().rxdr().read().rxdata();
+                unsafe {
+                    *byte = T::regs().rxdr().read().rxdata();
+                }
             }
         }
-
-        // automatic STOP
         Ok(())
     }
-}
 
-impl<'d, T: Instance> Write for I2c<'d, T> {
-    type Error = Error;
-
-    fn write(&mut self, address: u8, bytes: &[u8]) -> Result<(), Self::Error> {
-        // TODO support transfers of more than 255 bytes
-        assert!(bytes.len() < 256 && bytes.len() > 0);
+    fn write(&mut self, address: u8, bytes: &[u8], send_stop: bool) -> Result<(), Error> {
+        let last_chunk = (bytes.len() / 255).saturating_sub(1);
 
         // I2C start
         //
         // ST SAD+W
-        self.master_write(address, bytes.len(), Stop::Software);
+        self.master_write(
+            address,
+            bytes.len().min(255),
+            Stop::Software,
+            last_chunk != 0,
+        );
 
-        for byte in bytes {
-            // Wait until we are allowed to send data
-            // (START has been ACKed or last byte when
-            // through)
-            self.wait_txe()?;
+        for (number, chunk) in bytes.chunks(255).enumerate() {
+            if number != 0 {
+                self.master_continue(chunk.len(), number != last_chunk);
+            }
 
-            // Put byte on the wire
-            //self.i2c.txdr.write(|w| w.txdata().bits(*byte));
-            unsafe {
-                T::regs().txdr().write(|w| w.set_txdata(*byte));
+            for byte in chunk {
+                // Wait until we are allowed to send data
+                // (START has been ACKed or last byte when
+                // through)
+                self.wait_txe()?;
+
+                // Put byte on the wire
+                //self.i2c.txdr.write(|w| w.txdata().bits(*byte));
+                unsafe {
+                    T::regs().txdr().write(|w| w.set_txdata(*byte));
+                }
             }
         }
-
         // Wait until the write finishes
         self.wait_tc()?;
 
-        // Stop
-        self.master_stop();
-
+        if send_stop {
+            self.master_stop();
+        }
         Ok(())
     }
 }
 
+impl<'d, T: Instance> Read for I2c<'d, T> {
+    type Error = Error;
+
+    fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Self::Error> {
+        self.read(address, buffer, false)
+        // Automatic Stop
+    }
+}
+
+impl<'d, T: Instance> Write for I2c<'d, T> {
+    type Error = Error;
+
+    fn write(&mut self, address: u8, bytes: &[u8]) -> Result<(), Self::Error> {
+        self.write(address, bytes, true)
+    }
+}
+
 impl<'d, T: Instance> WriteRead for I2c<'d, T> {
     type Error = Error;
 
@@ -293,48 +339,9 @@ impl<'d, T: Instance> WriteRead for I2c<'d, T> {
         bytes: &[u8],
         buffer: &mut [u8],
     ) -> Result<(), Self::Error> {
-        // TODO support transfers of more than 255 bytes
-        assert!(bytes.len() < 256 && bytes.len() > 0);
-        assert!(buffer.len() < 256 && buffer.len() > 0);
-
-        // I2C start
-        //
-        // ST SAD+W
-        self.master_write(address, bytes.len(), Stop::Software);
-
-        for byte in bytes {
-            // Wait until we are allowed to send data
-            // (START has been ACKed or last byte went through)
-            self.wait_txe()?;
-
-            // Put byte on the wire
-            //self.i2c.txdr.write(|w| w.txdata().bits(*byte));
-            unsafe {
-                T::regs().txdr().write(|w| w.set_txdata(*byte));
-            }
-        }
-
-        // Wait until the write finishes before beginning to read.
-        self.wait_tc()?;
-
-        // I2C re-start
-        //
-        // SR  SAD+R
-        self.master_re_start(address, buffer.len(), Stop::Automatic);
-
-        for byte in buffer {
-            // Wait until we have received something
-            self.wait_rxne()?;
-
-            //*byte = self.i2c.rxdr.read().rxdata().bits();
-            unsafe {
-                *byte = T::regs().rxdr().read().rxdata();
-            }
-        }
-
-        // automatic STOP
-
-        Ok(())
+        self.write(address, bytes, false)?;
+        self.read(address, buffer, true)
+        // Automatic Stop
     }
 }