From 563ec45c6e69080b06446a1461d277564f47cac3 Mon Sep 17 00:00:00 2001
From: Pavel Kirienko <pavel.kirienko@gmail.com>
Date: Mon, 12 Oct 2015 04:07:13 +0300
Subject: [PATCH] LPC11C24 auto bit rate detection is sort of working

---
 .../lpc11c24/driver/src/c_can.hpp             |  2 +-
 libuavcan_drivers/lpc11c24/driver/src/can.cpp | 58 +++++++++++--------
 2 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/libuavcan_drivers/lpc11c24/driver/src/c_can.hpp b/libuavcan_drivers/lpc11c24/driver/src/c_can.hpp
index fe2ef1ccf2..cbeb035ea5 100644
--- a/libuavcan_drivers/lpc11c24/driver/src/c_can.hpp
+++ b/libuavcan_drivers/lpc11c24/driver/src/c_can.hpp
@@ -101,7 +101,7 @@ static_assert(offsetof(Type, IF[0].DB2) == 0x048, "C_CAN offset");
 static_assert(offsetof(Type, IF[1].DB2) == 0x0A8, "C_CAN offset");
 
 
-Type& CAN = *reinterpret_cast<Type*>(0x40050000);
+volatile Type& CAN = *reinterpret_cast<volatile Type*>(0x40050000);
 
 
 /*
diff --git a/libuavcan_drivers/lpc11c24/driver/src/can.cpp b/libuavcan_drivers/lpc11c24/driver/src/can.cpp
index cc8aadd53d..0ab31fc3d6 100644
--- a/libuavcan_drivers/lpc11c24/driver/src/can.cpp
+++ b/libuavcan_drivers/lpc11c24/driver/src/can.cpp
@@ -156,9 +156,6 @@ BitTimingSettings computeBitTimings(std::uint32_t bitrate)
 
 CanDriver CanDriver::self;
 
-#if __GNUC__
-__attribute__((optimize(1)))
-#endif
 uavcan::uint32_t CanDriver::detectBitRate(void (*idle_callback)())
 {
     static constexpr uavcan::uint32_t BitRatesToTry[] =
@@ -172,7 +169,6 @@ uavcan::uint32_t CanDriver::detectBitRate(void (*idle_callback)())
     const auto ListeningDuration = uavcan::MonotonicDuration::fromMSec(1050);
 
     NVIC_DisableIRQ(CAN_IRQn);
-    LPC_SYSCTL->PRESETCTRL |= (1 << RESET_CAN0);
     Chip_Clock_EnablePeriphClock(SYSCTL_CLOCK_CAN);
 
     for (auto bitrate : BitRatesToTry)
@@ -188,24 +184,35 @@ uavcan::uint32_t CanDriver::detectBitRate(void (*idle_callback)())
         {
             CriticalSectionLocker locker;
 
-            c_can::CAN.CNTL = c_can::CNTL_INIT | c_can::CNTL_CCE | c_can::CNTL_TEST;
+            LPC_SYSCTL->PRESETCTRL |= (1U << RESET_CAN0);
 
+            // Entering initialization mode
+            c_can::CAN.CNTL = c_can::CNTL_INIT | c_can::CNTL_CCE;
+
+            while ((c_can::CAN.CNTL & c_can::CNTL_INIT) == 0)
+            {
+                ; // Nothing to do
+            }
+
+            // Configuring bit rate
             c_can::CAN.CLKDIV = bit_timings.canclkdiv;
+            c_can::CAN.BT     = bit_timings.canbtr;
+            c_can::CAN.BRPE   = 0;
 
-            c_can::CAN.BRPE = 0;
-            c_can::CAN.BT   = bit_timings.canbtr;
-
+            // Configuring silent mode
+            c_can::CAN.CNTL |= c_can::CNTL_TEST;
             c_can::CAN.TEST = c_can::TEST_SILENT;
 
+            // Configuring status monitor
             c_can::CAN.STAT = (unsigned(c_can::StatLec::Unused) << c_can::STAT_LEC_SHIFT);
 
-            c_can::CAN.CNTL = c_can::CNTL_TEST;
-        }
+            // Leaving initialization mode
+            c_can::CAN.CNTL &= ~(c_can::CNTL_INIT | c_can::CNTL_CCE);
 
-        // TODO THIS IS TEMPORARY, REMOVE LATER
-        if (c_can::CAN.BT != bit_timings.canbtr)
-        {
-            Chip_UART_SendBlocking(LPC_USART, "BT\r\n", 4);
+            while ((c_can::CAN.CNTL & c_can::CNTL_INIT) != 0)
+            {
+                ; // Nothing to do
+            }
         }
 
         // Listening
@@ -220,16 +227,6 @@ uavcan::uint32_t CanDriver::detectBitRate(void (*idle_callback)())
 
             const auto LastErrorCode = (c_can::CAN.STAT >> c_can::STAT_LEC_SHIFT) & c_can::STAT_LEC_MASK;
 
-            // TODO THIS IS TEMPORARY, REMOVE LATER
-            if (LastErrorCode != unsigned(c_can::StatLec::Unused) &&
-                LastErrorCode != unsigned(c_can::StatLec::NoError))
-            {
-                const char txt[] = { 'E', char('0' + LastErrorCode), ' ',
-                                     'R', (((c_can::CAN.STAT & c_can::STAT_RXOK) != 0) ? '1' : '0'),
-                                     '\r', '\n' };
-                Chip_UART_SendBlocking(LPC_USART, txt, sizeof(txt));
-            }
-
             if (LastErrorCode == unsigned(c_can::StatLec::NoError))
             {
                 match_detected = true;
@@ -238,7 +235,18 @@ uavcan::uint32_t CanDriver::detectBitRate(void (*idle_callback)())
         }
 
         // De-configuring the CAN controller back to reset state
-        c_can::CAN.CNTL = c_can::CNTL_INIT;
+        {
+            CriticalSectionLocker locker;
+
+            c_can::CAN.CNTL = c_can::CNTL_INIT;
+
+            while ((c_can::CAN.CNTL & c_can::CNTL_INIT) == 0)
+            {
+                ; // Nothing to do
+            }
+
+            LPC_SYSCTL->PRESETCTRL &= ~(1U << RESET_CAN0);
+        }
 
         // Termination condition
         if (match_detected)