From fe211d1b88e0ff883fdb142c3473a169e0d548eb Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Sun, 2 Aug 2015 11:18:51 -0600
Subject: [PATCH] SAMV7 MCAN: remove old AUTOBAUD option; add a local LOOPBACK
 option

---
 arch/arm/src/samv7/Kconfig    |  8 ++--
 arch/arm/src/samv7/sam_mcan.c | 84 -----------------------------------
 2 files changed, 3 insertions(+), 89 deletions(-)

diff --git a/arch/arm/src/samv7/Kconfig b/arch/arm/src/samv7/Kconfig
index 99f963c5fe..2b7ad366a8 100644
--- a/arch/arm/src/samv7/Kconfig
+++ b/arch/arm/src/samv7/Kconfig
@@ -1836,13 +1836,11 @@ config SAMV7_MCAN1_DEDICATED_TXFIFOQ_SIZE
 
 endmenu # MCAN1 device driver options
 
-config SAMV7_MCAN_AUTOBAUD
-	bool "Enable auto-baud"
+config SAMV7_MCAN_LOOPBACK
+	bool "Enable loopback mode"
 	default n
-	depends on EXPERIMENTAL
 	---help---
-		Enable the SAMV7 auto-baud feature.  NOTE:  This feature is not yet
-		fully implemented.
+		Enable the MCAN local loopback mode for testing purposes.
 
 config SAMV7_MCAN_REGDEBUG
 	bool "CAN Register level debug"
diff --git a/arch/arm/src/samv7/sam_mcan.c b/arch/arm/src/samv7/sam_mcan.c
index 7c47d0dd72..6d9b3f94ae 100644
--- a/arch/arm/src/samv7/sam_mcan.c
+++ b/arch/arm/src/samv7/sam_mcan.c
@@ -711,9 +711,6 @@ static int  mcan1_interrupt(int irq, void *context);
 /* Hardware initialization */
 
 static int  mcan_bittiming(FAR struct sam_mcan_s *priv);
-#ifdef CONFIG_SAMV7_MCAN_AUTOBAUD
-static int  mcan_autobaud(FAR struct sam_mcan_s *priv);
-#endif
 static int  mcan_hwinitialize(FAR struct sam_mcan_s *priv);
 
 /****************************************************************************
@@ -2261,76 +2258,6 @@ static int mcan_bittiming(struct sam_mcan_s *priv)
   return OK;
 }
 
-/****************************************************************************
- * Name: mcan_autobaud
- *
- * Description:
- *   Use the SAMV7 auto-baud feature to correct the initial timing
- *
- * Input Parameter:
- *   priv - A pointer to the private data structure for this CAN block
- *
- * Returned Value:
- *   Zero on success; a negated errno value on failure.
- *
- ****************************************************************************/
-
-#ifdef CONFIG_SAMV7_MCAN_AUTOBAUD
-static int mcan_autobaud(struct sam_mcan_s *priv)
-{
-  volatile uint32_t timeout;
-  uint32_t regval;
-  int ret;
-
-  canllvdbg("CAN%d\n", config->port);
-
-  /* The CAN controller can start listening to the network in Autobaud Mode.
-   * In this case, the error counters are locked and a mailbox may be
-   * configured in Receive Mode. By scanning error flags, the CAN_BR
-   * register values synchronized with the network.
-   */
-
-  /* Configure a Mailbox in Reception Mode */
-#warning Missing Logic
-
-  /* Loop, adjusting bit rate parameters until no errors are reported in
-   * either CAR_SR or the CAN_MSRx registers.
-   */
-
-  do
-    {
-      /* Adjust baud rate setting */
-#warning Missing Logic
-
-      /* Autobaud Mode. The autobaud feature is enabled by setting the ABM
-       * field in the CAN_MR register. In this mode, the CAN controller is only
-       * listening to the line without acknowledging the received messages. It
-       * can not send any message. The errors flags are updated. The bit timing
-       * can be adjusted until no error occurs (good configuration found). In
-       * this mode, the error counters are frozen.
-       */
-
-      regval  = mcan_getreg(priv, SAM_CAN_MR_OFFSET);
-      regval |= (CAN_MR_CANEN | CAN_MR_ABM);
-      mcan_putreg(priv, SAM_CAN_MR_OFFSET, regval);
-
-#warning Missing logic
-    }
-  while (no errors reported);
-
-  /* Once no error has been detected, the application disables the Autobaud
-   * Mode, clearing the ABM field in the CAN_MR register.  To go back to the
-   * standard mode, the ABM bit must be cleared in the CAN_MR register.
-   */
-
-  regval  = mcan_getreg(priv, SAM_CAN_MR_OFFSET);
-  regval &= ~(CAN_MR_CANEN | CAN_MR_ABM);
-  mcan_putreg(priv, SAM_CAN_MR_OFFSET, regval);
-
-  return OK;
-}
-#endif
-
 /****************************************************************************
  * Name: mcan_hwinitialize
  *
@@ -2410,17 +2337,6 @@ static int mcan_hwinitialize(struct sam_mcan_s *priv)
       return ret;
     }
 
-#ifdef CONFIG_SAMV7_MCAN_AUTOBAUD
-  /* Optimize/correct bit timing */
-
-  ret = mcan_autobaud(priv);
-  if (ret < 0)
-    {
-      candbg("ERROR: mcan_autobaud failed: %d\n", ret);
-      return ret;
-    }
-#endif
-
   /* The CAN controller is enabled by setting the CANEN flag in the CAN_MR
    * register. At this stage, the internal CAN controller state machine is
    * reset, error counters are reset to 0, error flags are reset to 0.