From 4f201a63c9d7de8e1d19eea0a51e130aa875ef0a Mon Sep 17 00:00:00 2001
From: iamkroot <kroot.patel@gmail.com>
Date: Mon, 15 Nov 2021 21:31:51 +0530
Subject: [PATCH 1/2] Allow forcefully setting slave address

Closes #59
---
 CHANGELOG.md |  1 +
 src/ffi.rs   | 10 +++++++++-
 src/linux.rs | 31 +++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ac56172..d2fd5dff 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 - Updated nix to allow both version `0.22` or `0.23`.
 - Add PEC support for SMBus compatible adapters
+- Add `LinuxI2CDevice::force_new()` to open the device without checking if it is bound to a driver.
 
 ## [v0.5.0] - 2021-09-21
 
diff --git a/src/ffi.rs b/src/ffi.rs
index 6d5b0fac..61a44a7e 100644
--- a/src/ffi.rs
+++ b/src/ffi.rs
@@ -153,9 +153,10 @@ pub struct i2c_rdwr_ioctl_data {
 mod ioctl {
     pub use super::i2c_rdwr_ioctl_data;
     pub use super::i2c_smbus_ioctl_data;
-    use super::{I2C_PEC, I2C_RDWR, I2C_SLAVE, I2C_SMBUS};
+    use super::{I2C_PEC, I2C_RDWR, I2C_SLAVE, I2C_SLAVE_FORCE, I2C_SMBUS};
 
     ioctl_write_int_bad!(set_i2c_slave_address, I2C_SLAVE);
+    ioctl_write_int_bad!(set_i2c_slave_address_force, I2C_SLAVE_FORCE);
     ioctl_write_int_bad!(set_smbus_pec, I2C_PEC);
     ioctl_write_ptr_bad!(i2c_smbus, I2C_SMBUS, i2c_smbus_ioctl_data);
     ioctl_write_ptr_bad!(i2c_rdwr, I2C_RDWR, i2c_rdwr_ioctl_data);
@@ -168,6 +169,13 @@ pub fn i2c_set_slave_address(fd: RawFd, slave_address: u16) -> Result<(), nix::E
     Ok(())
 }
 
+pub fn i2c_set_slave_address_force(fd: RawFd, slave_address: u16) -> Result<(), nix::Error> {
+    unsafe {
+        ioctl::set_i2c_slave_address_force(fd, i32::from(slave_address))?;
+    }
+    Ok(())
+}
+
 pub fn i2c_set_smbus_pec(fd: RawFd, enable: bool) -> Result<(), nix::Error> {
     unsafe {
         ioctl::set_smbus_pec(fd, i32::from(enable))?;
diff --git a/src/linux.rs b/src/linux.rs
index e46b03a0..67d09ff3 100644
--- a/src/linux.rs
+++ b/src/linux.rs
@@ -110,6 +110,27 @@ impl LinuxI2CDevice {
         Ok(device)
     }
 
+    /// Create a new I2CDevice for the specified path, without checking if the
+    /// device is bound to a driver
+    ///
+    /// # Safety
+    /// Using this can seriously confuse the original driver, and may cause all
+    /// future communication to perform the wrong operations and/or return wrong results.
+    pub unsafe fn force_new<P: AsRef<Path>>(
+        path: P,
+        slave_address: u16,
+    ) -> Result<LinuxI2CDevice, LinuxI2CError> {
+        let file = OpenOptions::new().read(true).write(true).open(path)?;
+        let mut device = LinuxI2CDevice {
+            devfile: file,
+            slave_address: 0, // will be set later
+            pec: false,
+        };
+        device.force_set_slave_address(slave_address)?;
+        device.set_smbus_pec(false)?;
+        Ok(device)
+    }
+
     /// Set the slave address for this device
     ///
     /// Typically the address is expected to be 7-bits but 10-bit addresses
@@ -127,6 +148,16 @@ impl LinuxI2CDevice {
         Ok(())
     }
 
+    /// Set the slave address for this device, even if it is already in use
+    /// by a driver
+    ///
+    /// This is private; use `force_new` instead.
+    unsafe fn force_set_slave_address(&mut self, slave_address: u16) -> Result<(), LinuxI2CError> {
+        ffi::i2c_set_slave_address_force(self.as_raw_fd(), slave_address)?;
+        self.slave_address = slave_address;
+        Ok(())
+    }
+
     /// Enable/Disable PEC support for this device
     ///
     /// Used only for SMBus transactions.  This request only has an effect if the

From c70d87a73c62707dc69f2b15905f1a115bb29fac Mon Sep 17 00:00:00 2001
From: Diego Barrios Romero <eldruin@gmail.com>
Date: Tue, 16 Nov 2021 13:18:10 +0100
Subject: [PATCH 2/2] Update CHANGELOG.md

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2fd5dff..b71da4ba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,7 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 - Updated nix to allow both version `0.22` or `0.23`.
 - Add PEC support for SMBus compatible adapters
-- Add `LinuxI2CDevice::force_new()` to open the device without checking if it is bound to a driver.
+- Add `LinuxI2CDevice::force_new()` to open the device without checking if the address is bound to a driver.
 
 ## [v0.5.0] - 2021-09-21