From a2e445cf243e2ba444395776a9efd73ca4d769bb Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Fri, 9 Dec 2016 12:58:34 +1100
Subject: [PATCH] HAL_Linux: implement set_split_transfers() API for I2C

---
 libraries/AP_HAL_Linux/I2CDevice.cpp | 10 ++++++++++
 libraries/AP_HAL_Linux/I2CDevice.h   |  6 ++++++
 2 files changed, 16 insertions(+)

diff --git a/libraries/AP_HAL_Linux/I2CDevice.cpp b/libraries/AP_HAL_Linux/I2CDevice.cpp
index c11fffac66..891074e8d0 100644
--- a/libraries/AP_HAL_Linux/I2CDevice.cpp
+++ b/libraries/AP_HAL_Linux/I2CDevice.cpp
@@ -154,6 +154,16 @@ I2CDevice::~I2CDevice()
 bool I2CDevice::transfer(const uint8_t *send, uint32_t send_len,
                          uint8_t *recv, uint32_t recv_len)
 {
+    if (send_len > 0 && recv_len > 0 && _split_transfers) {
+        /*
+          optionally split all I2C transfers. This is needed for some
+          devices (such as LidarLite) that require that STOP only
+          happen with SCL high
+         */
+        return transfer(send, send_len, nullptr, 0) &&
+            transfer(nullptr, 0, recv, recv_len);
+    }
+    
     struct i2c_msg msgs[2] = { };
     unsigned nmsgs = 0;
 
diff --git a/libraries/AP_HAL_Linux/I2CDevice.h b/libraries/AP_HAL_Linux/I2CDevice.h
index cede381460..0cb5ba829a 100644
--- a/libraries/AP_HAL_Linux/I2CDevice.h
+++ b/libraries/AP_HAL_Linux/I2CDevice.h
@@ -71,10 +71,16 @@ public:
     bool adjust_periodic_callback(
         AP_HAL::Device::PeriodicHandle h, uint32_t period_usec) override;
 
+    /* set split transfers flag */
+    void set_split_transfers(bool set) override {
+        _split_transfers = set;
+    }
+    
 protected:
     I2CBus &_bus;
     uint8_t _address;
     uint8_t _retries = 0;
+    bool _split_transfers = false;
 };
 
 class I2CDeviceManager : public AP_HAL::I2CDeviceManager {