Adds drain ioctl. (#539)

* Adds an IOCTL to the CC32xx UART driver that allows getting a notification when transmission has completed. * Adds comment. * removes unnecessary volatile tag
bakerstu · May 8, 2021 · 3ccdbb7 · 3ccdbb7
1 parent f3f1882
commit 3ccdbb7
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Showing 3 changed files with 40 additions and 0 deletions.
diff --git a/include/freertos/tc_ioctl.h b/include/freertos/tc_ioctl.h
@@ -47,5 +47,10 @@
 #define TCPARONE    IO(TERMIOS_IOC_MAGIC, 0xF3)
 #define TCPARZERO   IO(TERMIOS_IOC_MAGIC, 0xF4)
 
+/// Argument is a Notifiable* pointer. This notifiable will be invoked when all
+/// bytes have completed transferring and the transmit engine is idle.
+#define TCDRAINNOTIFY   IOW(TERMIOS_IOC_MAGIC, 0xE0, 4)
+
+
 #endif // _FREERTOS_TC_IOCTL_H_
 
diff --git a/src/freertos_drivers/ti/CC32xxUart.cxx b/src/freertos_drivers/ti/CC32xxUart.cxx
@@ -43,11 +43,14 @@
 #include "driverlib/prcm.h"
 #include "driverlib/utils.h"
 #include "freertos/tc_ioctl.h"
+#include "executor/Notifiable.hxx"
 
 #include "CC32xxUart.hxx"
 
 /** Instance pointers help us get context from the interrupt handler(s) */
 static CC32xxUart *instances[2] = {NULL};
+/** Critical section lock between ISR and ioctl */
+static Atomic isr_lock;
 
 /** Constructor.
  * @param name name of this device instance in the file system
@@ -155,6 +158,27 @@ int CC32xxUart::ioctl(File *file, unsigned long int key, unsigned long data)
         case TCPARZERO:
             MAP_UARTParityModeSet(base, UART_CONFIG_PAR_ZERO);
             break;
+        case TCDRAINNOTIFY:
+        {
+            Notifiable* arg = (Notifiable*)data;
+            {
+                AtomicHolder h(&isr_lock);
+                if (txComplete != nullptr)
+                {
+                    return -EBUSY;
+                }
+                if (txPending)
+                {
+                    txComplete = arg;
+                    arg = nullptr;
+                }
+            }
+            if (arg)
+            {
+                arg->notify();
+            }
+            break;
+        }
     }
 
     return 0;
@@ -254,6 +278,12 @@ void CC32xxUart::interrupt_handler()
                 txEnableDeassert();
             }
             txPending = false;
+            if (txComplete)
+            {
+                Notifiable *t = txComplete;
+                txComplete = nullptr;
+                t->notify_from_isr();
+            }
             MAP_UARTIntDisable(base, UART_INT_TX);
         }
     }

diff --git a/src/freertos_drivers/ti/CC32xxUart.hxx b/src/freertos_drivers/ti/CC32xxUart.hxx
@@ -44,6 +44,8 @@
 
 #include "driverlib/uart.h"
 
+class Notifiable;
+
 /** Specialization of Serial driver for CC32xx UART.
  */
 class CC32xxUart : public Serial
@@ -110,6 +112,9 @@ private:
     /** function pointer to a method that deasserts the transmit enable. */
     TxEnableMethod txEnableDeassert;
 
+    /** Notifiable to invoke when the transmit engine has finished operation. */
+    Notifiable* txComplete{nullptr};
+
     unsigned long base; /**< base address of this device */
     unsigned long interrupt; /**< interrupt of this device */
     bool txPending; /**< transmission currently pending */