sched: Introduce sched_wake_tasks() function to wake up tasks

Add function to indicate when tasks need to be run.  This will allow
the scheduler code to know if there are any tasks that need to be
processed.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

lib/README

@@ -3,7 +3,9 @@ This directory contains external library code.
 The pjrc_usb_serial directory contains code from:
   http://www.pjrc.com/teensy/usb_serial.html
 version 1.7 (extracted on 20160605). It has been modified to compile
-on recent versions of gcc. See usb_serial.patch for the modifications.
+on recent versions of gcc, to support asynchronous notification of
+incoming data, and to not use SOF interrupts. See usb_serial.patch for
+the modifications.
 
 The cmsis-sam3x8e directory contains code from the Arduino project:
   https://www.arduino.cc/

lib/pjrc_usb_serial/usb_serial.c

@@ -325,7 +325,7 @@ void usb_init(void)
         UDCON = 0;				// enable attach resistor
 	usb_configuration = 0;
 	cdc_line_rtsdtr = 0;
-        UDIEN = (1<<EORSTE)|(1<<SOFE);
+        UDIEN = (1<<EORSTE);
 	sei();
 }
 
@@ -359,6 +359,7 @@ int16_t usb_serial_getchar(void)
 			UEINTX = 0x6B;
 			goto retry;
 		}	
+		UEIENX = (1<<RXOUTE);
 		SREG = intr_state;
 		return -1;
 	}
@@ -775,7 +776,14 @@ static inline void usb_ack_out(void)
 //
 ISR(USB_COM_vect)
 {
-        uint8_t intbits;
+        uint8_t intbits = UEINT;
+        if (intbits & (1<<CDC_RX_ENDPOINT)) {
+                UENUM = CDC_RX_ENDPOINT;
+                UEIENX = 0;
+                extern void sched_wake_tasks(void);
+                sched_wake_tasks();
+                return;
+        }
 	const uint8_t *list;
         const uint8_t *cfg;
 	uint8_t i, n, len, en;

lib/pjrc_usb_serial/usb_serial.patch

@@ -1,5 +1,5 @@
---- usb_serial.c	2011-04-19 05:54:12.000000000 -0400
-+++ usb_serial.c	2016-06-04 23:48:52.590001697 -0400
+--- ../../../lib/pjrc/usb_serial/usb_serial.c	2011-04-19 05:54:12.000000000 -0400
++++ usb_serial.c	2017-08-07 11:32:47.106357362 -0400
 @@ -30,6 +30,7 @@
  // Version 1.6: fix zero length packet bug
  // Version 1.7: fix usb_serial_set_control
@@ -62,7 +62,24 @@
  	uint16_t	wValue;
  	uint16_t	wIndex;
  	const uint8_t	*addr;
-@@ -646,7 +647,9 @@
+@@ -324,7 +325,7 @@
+         UDCON = 0;				// enable attach resistor
+ 	usb_configuration = 0;
+ 	cdc_line_rtsdtr = 0;
+-        UDIEN = (1<<EORSTE)|(1<<SOFE);
++        UDIEN = (1<<EORSTE);
+ 	sei();
+ }
+ 
+@@ -358,6 +359,7 @@
+ 			UEINTX = 0x6B;
+ 			goto retry;
+ 		}	
++		UEIENX = (1<<RXOUTE);
+ 		SREG = intr_state;
+ 		return -1;
+ 	}
+@@ -646,7 +648,9 @@
  // communication
  uint32_t usb_serial_get_baud(void)
  {
@@ -73,3 +90,19 @@
  }
  uint8_t usb_serial_get_stopbits(void)
  {
+@@ -772,7 +776,14 @@
+ //
+ ISR(USB_COM_vect)
+ {
+-        uint8_t intbits;
++        uint8_t intbits = UEINT;
++        if (intbits & (1<<CDC_RX_ENDPOINT)) {
++                UENUM = CDC_RX_ENDPOINT;
++                UEIENX = 0;
++                extern void sched_wake_tasks(void);
++                sched_wake_tasks();
++                return;
++        }
+ 	const uint8_t *list;
+         const uint8_t *cfg;
+ 	uint8_t i, n, len, en;

src/avr/serial.c

@@ -65,6 +65,8 @@ DECL_INIT(serial_init);
 ISR(USART0_RX_vect)
 {
     uint8_t data = UDR0;
+    if (data == MESSAGE_SYNC)
+        sched_wake_tasks();
     if (receive_pos >= sizeof(receive_buf))
         // Serial overflow - ignore it as crc error will force retransmit
         return;
@@ -104,6 +106,7 @@ console_pop_input(uint8_t len)
             memmove(&receive_buf[copied], &receive_buf[copied + len]
                     , needcopy - copied);
             copied = needcopy;
+            sched_wake_tasks();
         }
         irqstatus_t flag = irq_save();
         if (rpos != readb(&receive_pos)) {

src/avr/usbserial.c

@@ -42,8 +42,10 @@ static void
 console_pop_input(uint8_t len)
 {
     uint8_t needcopy = receive_pos - len;
-    if (needcopy)
+    if (needcopy) {
         memmove(receive_buf, &receive_buf[len], needcopy);
+        sched_wake_tasks();
+    }
     receive_pos = needcopy;
 }
 

src/command.c

@@ -11,7 +11,7 @@
 #include "board/misc.h" // crc16_ccitt
 #include "board/pgm.h" // READP
 #include "command.h" // output_P
-#include "sched.h" // DECL_TASK
+#include "sched.h" // sched_is_shutdown
 
 static uint8_t next_sequence = MESSAGE_DEST;
 

src/pru/main.c

@@ -85,7 +85,10 @@ timer_kick(void)
 static void
 _irq_poll(void)
 {
-    if (CT_INTC.SECR0 & (1 << IEP_EVENT)) {
+    uint32_t secr0 = CT_INTC.SECR0;
+    if (secr0 & (1 << KICK_PRU1_EVENT))
+        sched_wake_tasks();
+    if (secr0 & (1 << IEP_EVENT)) {
         CT_IEP.TMR_CMP_STS = 0xff;
         uint32_t next = timer_dispatch_many();
         timer_set(next);
@@ -121,7 +124,6 @@ console_task(void)
     const struct command_parser *cp = SHARED_MEM->next_command;
     if (!cp)
         return;
-    barrier();
 
     if (sched_is_shutdown() && !(cp->flags & HF_IN_SHUTDOWN)) {
         sched_report_shutdown();

src/sam3x8e/serial.c

@@ -56,6 +56,8 @@ UART_Handler(void)
     uint32_t status = UART->UART_SR;
     if (status & UART_SR_RXRDY) {
         uint8_t data = UART->UART_RHR;
+        if (data == MESSAGE_SYNC)
+            sched_wake_tasks();
         if (receive_pos >= sizeof(receive_buf))
             // Serial overflow - ignore it as crc error will force retransmit
             return;
@@ -94,6 +96,7 @@ console_pop_input(uint32_t len)
             memmove(&receive_buf[copied], &receive_buf[copied + len]
                     , needcopy - copied);
             copied = needcopy;
+            sched_wake_tasks();
         }
         irqstatus_t flag = irq_save();
         if (rpos != readl(&receive_pos)) {

src/sched.c

@@ -28,6 +28,9 @@ static struct timer sentinel_timer, deleted_timer;
 static uint_fast8_t
 periodic_event(struct timer *t)
 {
+    // Make sure the stats task runs periodically
+    sched_wake_tasks();
+    // Reschedule timer
     periodic_timer.waketime += timer_from_us(100000);
     sentinel_timer.waketime = periodic_timer.waketime + 0x80000000;
     return SF_RESCHEDULE;
@@ -177,10 +180,17 @@ sched_timer_reset(void)
  * Task waking
  ****************************************************************/
 
+// Note that at least one task is ready to run
+void
+sched_wake_tasks(void)
+{
+}
+
 // Note that a task is ready to run
 void
 sched_wake_task(struct task_wake *w)
 {
+    sched_wake_tasks();
     writeb(&w->wake, 1);
 }
 

src/sched.h

@@ -29,6 +29,7 @@ struct task_wake {
 void sched_add_timer(struct timer*);
 void sched_del_timer(struct timer *del);
 unsigned int sched_timer_dispatch(void);
+void sched_wake_tasks(void);
 void sched_wake_task(struct task_wake *w);
 uint8_t sched_check_wake(struct task_wake *w);
 uint8_t sched_is_shutdown(void);