From 3e5514653fd13a27b3be504513478503e8b9de2d Mon Sep 17 00:00:00 2001
From: Tom Dohrmann <erbse.13@gmx.de>
Date: Sun, 26 Jan 2025 17:34:33 +0100
Subject: [PATCH] remove checks for reserved I2c addresses

There are some non-compliant devices that respond to reserved I2c
addresses. rp2040 behaves sanely for these addresses, so let's just
allow using them.
---
 embassy-rp/src/i2c.rs       | 13 ++++---------
 embassy-rp/src/i2c_slave.rs |  5 +----
 2 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/embassy-rp/src/i2c.rs b/embassy-rp/src/i2c.rs
index 32778215f..3a2ee666c 100644
--- a/embassy-rp/src/i2c.rs
+++ b/embassy-rp/src/i2c.rs
@@ -1,3 +1,5 @@
+#![cfg_attr(feature = "defmt", allow(deprecated))] // Suppress warnings for defmt::Format using Error::AddressReserved
+
 //! I2C driver.
 use core::future;
 use core::marker::PhantomData;
@@ -40,6 +42,7 @@ pub enum Error {
     /// Target i2c address is out of range
     AddressOutOfRange(u16),
     /// Target i2c address is reserved
+    #[deprecated = "embassy_rp no longer prevents accesses to reserved addresses."]
     AddressReserved(u16),
 }
 
@@ -470,10 +473,6 @@ impl<'d, T: Instance + 'd, M: Mode> I2c<'d, T, M> {
             return Err(Error::AddressOutOfRange(addr));
         }
 
-        if i2c_reserved_addr(addr) {
-            return Err(Error::AddressReserved(addr));
-        }
-
         let p = T::regs();
         p.ic_enable().write(|w| w.set_enable(false));
         p.ic_tar().write(|w| w.set_ic_tar(addr));
@@ -680,6 +679,7 @@ impl embedded_hal_1::i2c::Error for Error {
             Self::InvalidReadBufferLength => embedded_hal_1::i2c::ErrorKind::Other,
             Self::InvalidWriteBufferLength => embedded_hal_1::i2c::ErrorKind::Other,
             Self::AddressOutOfRange(_) => embedded_hal_1::i2c::ErrorKind::Other,
+            #[allow(deprecated)]
             Self::AddressReserved(_) => embedded_hal_1::i2c::ErrorKind::Other,
         }
     }
@@ -775,11 +775,6 @@ impl<'d, T: Instance, M: Mode> embassy_embedded_hal::SetConfig for I2c<'d, T, M>
     }
 }
 
-/// Check if address is reserved.
-pub fn i2c_reserved_addr(addr: u16) -> bool {
-    ((addr & 0x78) == 0 || (addr & 0x78) == 0x78) && addr != 0
-}
-
 pub(crate) trait SealedInstance {
     fn regs() -> crate::pac::i2c::I2c;
     fn reset() -> crate::pac::resets::regs::Peripherals;
diff --git a/embassy-rp/src/i2c_slave.rs b/embassy-rp/src/i2c_slave.rs
index c46a55d2e..d17b11d14 100644
--- a/embassy-rp/src/i2c_slave.rs
+++ b/embassy-rp/src/i2c_slave.rs
@@ -6,9 +6,7 @@ use core::task::Poll;
 use embassy_hal_internal::into_ref;
 use pac::i2c;
 
-use crate::i2c::{
-    i2c_reserved_addr, set_up_i2c_pin, AbortReason, Instance, InterruptHandler, SclPin, SdaPin, FIFO_SIZE,
-};
+use crate::i2c::{set_up_i2c_pin, AbortReason, Instance, InterruptHandler, SclPin, SdaPin, FIFO_SIZE};
 use crate::interrupt::typelevel::{Binding, Interrupt};
 use crate::{pac, Peripheral};
 
@@ -97,7 +95,6 @@ impl<'d, T: Instance> I2cSlave<'d, T> {
     ) -> Self {
         into_ref!(_peri, scl, sda);
 
-        assert!(!i2c_reserved_addr(config.addr));
         assert!(config.addr != 0);
 
         // Configure SCL & SDA pins