Add basic context switching logic

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1777 42af7a65-404d-4744-a932-0658087f49c3

arch/arm/src/lm3s/Make.defs

@@ -45,9 +45,9 @@ CMN_CSRCS	= up_allocateheap.c up_assert.c up_blocktask.c up_copystate.c \
 		  up_sigdeliver.c up_syscall.c up_unblocktask.c \
 		  up_undefinedinsn.c up_usestack.c
 
-CHIP_ASRCS	= 
+CHIP_ASRCS	= lm3s_context.S
-CHIP_CSRCS	= lm3s_start.c lm3s_syscontrol.c lm3s_irq.c lm3s_timerisr.c \
+CHIP_CSRCS	= lm3s_start.c lm3s_syscontrol.c lm3s_irq.c lm3s_pendsv.c \
-		  lm3s_lowputc.c lm3s_serial.c
+		  lm3s_timerisr.c lm3s_lowputc.c lm3s_serial.c
 
 ifdef CONFIG_NET
 CHIP_CSRCS	+= lm3s_ethernet.c

arch/arm/src/lm3s/lm3s_context.S

@@ -0,0 +1,145 @@
+/************************************************************************************
+ * arch/arm/src/lm3s/lm3s_context.S
+ * arch/arm/src/chip/lm3s_context.S
+ *
+ *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************************************/
+
+/************************************************************************************
+ * Included Files
+ ************************************************************************************/
+
+#include <nuttx/config.h>
+#include <arch/irq.h>
+#include "cortexm3_nvic.h"
+
+/************************************************************************************
+ * Preprocessor Definitions
+ ************************************************************************************/
+
+/************************************************************************************
+ * Global Symbols
+ ************************************************************************************/
+
+	.syntax		unified
+	.thumb
+	.file		"lm3s_context.S"
+
+/************************************************************************************
+ * Macros
+ ************************************************************************************/
+
+/************************************************************************************
+ * Public Functions
+ ************************************************************************************/
+
+/**************************************************************************
+ * Name: up_saveusercontext
+ *
+ * Description:
+ *   Save the current thread context.  Full prototype is:
+ *
+ *   int  up_saveusercontext(uint32 *regs);
+ *
+ * Return:
+ *   0: Normal return
+ *   1: Context switch return
+ *
+ **************************************************************************/
+
+	.text
+	.thumb_func
+	.globl		up_saveusercontext
+	.type		up_saveusercontext, function
+up_saveusercontext:
+
+	/* Perform the System call with R0=0 and R1=regs */
+
+	ldr	r2, nvic_intctrl	/* R2: Address NVIC INTCTRL registers */
+	ldr	r3, [r2, #0]		/* R3: Contentx of NVIC INCTRL */
+	orr	r3, r3, #NVIC_INTCTRL_PENDSVSET
+	mov	r1, r0			/* R1: regs */
+	mov	r0, #0			/* R0: 0 means save context (also return value) */
+	str     r3, [r2, #0]		/* Force Pend SV */
+
+	/* There are two return conditions.  On the first return, R0 (the
+	 * return value will be zero.  On the second return we need to
+	 * force R0 to be 1.
+	 */
+
+	add	r2, r1, #(4*REG_R0)
+	mov	r3, #1
+	str	r3, [r2, #0]
+	bx	lr			/* "normal" return with r0=0 or
+					 * context switch with r0=1 */
+	.size		up_saveusercontext, .-up_saveusercontext
+
+
+/**************************************************************************
+ * Name: up_fullcontextrestore
+ *
+ * Description:
+ *   Restore the current thread context.  Full prototype is:
+ *
+ *   void up_fullcontextrestore(uint32 *regs) __attribute__ ((noreturn));
+ *
+ * Return:
+ *   None
+ *
+ **************************************************************************/
+
+	.thumb_func
+	.globl		up_fullcontextrestore
+	.type		up_fullcontextrestore, function
+up_fullcontextrestore:
+
+	/* Perform the System call with R0=1 and R1=regs */
+
+	ldr	r2, nvic_intctrl	/* R2: Address NVIC INTCTRL registers */
+	ldr	r3, [r2, #0]		/* R3: Contentx of NVIC INCTRL */
+	orr	r3, r3, #NVIC_INTCTRL_PENDSVSET
+	mov	r1, r0			/* R1: regs */
+	mov	r0, #1			/* R0: 1 means restore context */
+	str     r3, [r2, #0]		/* Force Pend SV */
+
+	/* These call should not return */
+
+	bx	lr			/* Unnecessary ... will not return */
+	.size		up_fullcontextrestore, .-up_fullcontextrestore
+
+        .align  2
+	.type		nvic_intctrl, object
+nvic_intctrl:
+        .word   NVIC_INTCTRL
+	.size		nvic_intctrl, .-nvic_intctrl
+        .end
+

arch/arm/src/lm3s/lm3s_internal.h

@@ -43,6 +43,10 @@
 #include <nuttx/config.h>
 #include <sys/types.h>
 
+#include "up_internal.h"
+#include "lm3s_memorymap.h"
+#include "lm3s_gpio.h"
+
 /************************************************************************************
  * Definitions
  ************************************************************************************/
@@ -247,6 +251,15 @@ EXTERN void up_clockconfig(void);
 
 EXTERN int lm3s_configgpio(uint32 bitset);
 
+/****************************************************************************
+ * Name: lm3s_pendsv
+ *
+ * Description:
+ *   This is PendSV exception handler that performs context switching
+ *
+ ****************************************************************************/
+
+EXTERN int lm3s_pendsv(int irq, FAR void *context);
 
 #undef EXTERN
 #if defined(__cplusplus)

arch/arm/src/lm3s/lm3s_irq.c

@@ -173,6 +173,12 @@ void up_irqinitialize(void)
 
   current_regs = NULL;
 
+  /* Attach the PendSV exception handler.  This is used for performing
+   * context switches.
+   */
+
+  irq_attach(LMSB_IRQ_PENDSV, lm3s_pendsv);
+
   /* Attach all processor exceptions (except reset and sys tick) */
 
 #ifdef CONFIG_DEBUG
@@ -183,7 +189,6 @@ void up_irqinitialize(void)
   irq_attach(LMSB_IRQ_USAGEFAULT, lm3s_usagefault);
   irq_attach(LMSB_IRQ_SVCALL, lm3s_svcall);
   irq_attach(LMSB_IRQ_DBGMONITOR, lm3s_dbgmonitor);
-  irq_attach(LMSB_IRQ_PENDSV, lm3s_pendsv);
   irq_attach(LMSB_IRQ_RESERVED, lm3s_reserved);
 #endif
 
@@ -368,14 +373,6 @@ int lm3s_dbgmonitor(int irq, FAR void *context)
   return 0;
 }
 
-int lm3s_pendsv(int irq, FAR void *context)
-{
-  (void)irqsave();
-  dbg("PANIC!!! PendSV received\n");
-  PANIC(OSERR_UNEXPECTEDISR);
-  return 0;
-}
-
 int lm3s_reserved(int irq, FAR void *context)
 {
   (void)irqsave();

arch/arm/src/lm3s/lm3s_pendsv.c

@@ -0,0 +1,118 @@
+/****************************************************************************
+ * arch/arm/src/lm3s/lm3s_pendsv.c
+ * arch/arm/src/chip/lm3s_pendsv.c
+ *
+ *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+
+#include <string.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <arch/irq.h>
+
+#include "os_internal.h"
+#include "lm3s_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lm3xs_pendxv
+ *
+ * Description:
+ *   This is PendSV exception handler that performs context switching
+ *
+ ****************************************************************************/
+
+int lm3s_pendsv(int irq, FAR void *context)
+{
+  uint32 *svregs  = (uint32*)context;
+  uint32 *tcbregs = (uint32*)svregs[REG_R1];
+
+  DEBUGASSERT(svregs && svregs == current_regs && tcbregs);
+
+  /* The PendSV software interrupt is called with R0 = PendSV command and R1 = 
+   * the TCB register save area.
+   */
+
+  switch (svregs[REG_R0])
+    {
+      /* R0=0:  This is a save context command.  In this case, we simply need
+       * to copy the svregs to the tdbregs and return.
+       */
+
+      case 0:
+        memcpy(tcbregs, svregs, XCPTCONTEXT_SIZE);
+        break;
+
+      /* R1=1: This a restore context command.  In this case, we simply need to
+       * set current_regs to tcbrgs.  svregs == current_regs is the normal exception
+       * turn.  By setting current_regs = tcbregs, we force the return through
+       * the saved context.
+       */
+
+      case 1:
+        current_regs = tcbregs;
+        break;
+
+      default:
+        PANIC(OSERR_INTERNAL);
+        break;
+    }
+
+  return OK;
+}

arch/arm/src/lm3s/lm3s_vectors.S

@@ -1,5 +1,6 @@
 /************************************************************************************
- * arch/arm/src/lm3s/lm3slm3s_vectors.S
+ * arch/arm/src/lm3s/lm3s_vectors.S
+ * arch/arm/src/chip/lm3s_vectors.S
  *
  *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>