src/spi.rs: add unsafe where required by stm32l4r9 PAC.

To make this implementation also usable by stm32l4+ devices,
some additional use of `unsafe` is necessary because of PAC differences.

Author: jspngh

src/spi.rs

@@ -110,7 +110,7 @@ macro_rules! hal {
                     // SSI: set nss high = master mode
                     // CRCEN: hardware CRC calculation disabled
                     // BIDIMODE: 2 line unidirectional (full duplex)
-                    spi.cr1.write(|w|
+                    spi.cr1.write(|w| unsafe {
                         w.cpha()
                             .bit(mode.phase == Phase::CaptureOnSecondTransition)
                             .cpol()
@@ -131,7 +131,7 @@ macro_rules! hal {
                             .clear_bit()
                             .bidimode()
                             .clear_bit()
-                    );
+                    });
 
                     Spi { spi, pins }
                 }
@@ -193,7 +193,7 @@ macro_rules! hal {
                     where F: Into<Hertz>
                 {
                     self.spi.cr1.modify(|_, w| w.spe().clear_bit());
-                    self.spi.cr1.modify(|_, w| {
+                    self.spi.cr1.modify(|_, w| unsafe {
                         w.br().bits(Self::compute_baud_rate(clocks.$pclkX(), freq.into()));
                         w.spe().set_bit()
                     });