/****************************************************************************
* arch/mips/src/mips32/up_swint0.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <stdint.h>
#include <string.h>
#include <syscall.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/sched.h>
#include <arch/irq.h>
#include <arch/mips32/cp0.h>
#include "up_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
#undef SYSCALL_INTERRUPTIBLE
#if defined(CONFIG_NUTTX_KERNEL)
# if CONFIG_ARCH_INTERRUPTSTACK > 3
# warning "CONFIG_ARCH_INTERRUPTSTACK and CONFIG_NUTTX_KERNEL are incompatible"
# warning "options as currently implemented. Interrupts will have to be disabled"
# warning "during SYScall processing to avoid un-handled nested interrupts"
# else
# define SYSCALL_INTERRUPTIBLE 1
# endif
#endif
/* Debug ********************************************************************/
/* Debug output from this file may interfere with context switching! To get
* debug output you must enabled the following in your NuttX configuration:
*
* CONFIG_DEBUG and CONFIG_DEBUG_SCHED
*
* And you must explicitly define DEBUG_SWINT0 below:
*/
#undef DEBUG_SWINT0 /* Define to debug SWInt */
#ifdef DEBUG_SWINT0
# define swidbg(format, arg...) slldbg(format, ##arg)
#else
# define swidbg(x...)
#endif
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: up_registerdump
****************************************************************************/
#ifdef DEBUG_SWINT0
static void up_registerdump(uint32_t *regs)
{
swidbg("MFLO:%08x MFHI:%08x EPC:%08x STATUS:%08x\n",
regs[REG_MFLO], regs[REG_MFHI], regs[REG_EPC], regs[REG_STATUS]);
swidbg("AT:%08x V0:%08x V1:%08x A0:%08x A1:%08x A2:%08x A3:%08x\n",
regs[REG_AT], regs[REG_V0], regs[REG_V1], regs[REG_A0],
regs[REG_A1], regs[REG_A2], regs[REG_A3]);
swidbg("T0:%08x T1:%08x T2:%08x T3:%08x T4:%08x T5:%08x T6:%08x T7:%08x\n",
regs[REG_T0], regs[REG_T1], regs[REG_T2], regs[REG_T3],
regs[REG_T4], regs[REG_T5], regs[REG_T6], regs[REG_T7]);
swidbg("S0:%08x S1:%08x S2:%08x S3:%08x S4:%08x S5:%08x S6:%08x S7:%08x\n",
regs[REG_S0], regs[REG_S1], regs[REG_S2], regs[REG_S3],
regs[REG_S4], regs[REG_S5], regs[REG_S6], regs[REG_S7]);
#ifdef MIPS32_SAVE_GP
swidbg("T8:%08x T9:%08x GP:%08x SP:%08x FP:%08x RA:%08x\n",
regs[REG_T8], regs[REG_T9], regs[REG_GP], regs[REG_SP],
regs[REG_FP], regs[REG_RA]);
#else
swidbg("T8:%08x T9:%08x SP:%08x FP:%08x RA:%08x\n",
regs[REG_T8], regs[REG_T9], regs[REG_SP], regs[REG_FP],
regs[REG_RA]);
#endif
}
#else
# define up_registerdump(regs)
#endif
/****************************************************************************
* Name: dispatch_syscall
*
* Description:
* Dispatch a system call to the appropriate handling logic.
*
****************************************************************************/
#ifdef CONFIG_NUTTX_KERNEL
static inline void dispatch_syscall(uint32_t *regs)
{
uint32_t cmd = regs[REG_A0];
FAR _TCB *rtcb = sched_self();
uintptr_t ret = (uintptr_t)ERROR;
/* Verify the the SYS call number is within range */
if (cmd < SYS_maxsyscall)
{
/* Report error and return ERROR */
slldbg("ERROR: Bad SYS call: %d\n", cmd);
}
else
{
/* The index into the syscall table is offset by the number of
* architecture-specific reserved entries at the beginning of the
* SYS call number space.
*/
int index = cmd - CONFIG_SYS_RESERVED;
/* Enable interrupts while the SYSCALL executes */
#ifdef SYSCALL_INTERRUPTIBLE
irqenable();
#endif
/* Call the correct stub for each SYS call, based on the number of
* parameters: $5=parm1, $6=parm2, $7=parm3, $8=parm4, $9=parm5, and
* $10=parm6.
*/
swidbg("Calling stub%d at %p\n", index, g_stubloopkup[index].stub0);
switch (g_stubnparms[index])
{
/* No parameters */
case 0:
ret = g_stublookup[index].stub0();
break;
/* Number of parameters: 1 */
case 1:
ret = g_stublookup[index].stub1(regs[REG_A1]);
break;
/* Number of parameters: 2 */
case 2:
ret = g_stublookup[index].stub2(regs[REG_A1], regs[REG_A2]);
break;
/* Number of parameters: 3 */
case 3:
ret = g_stublookup[index].stub3(regs[REG_A1], regs[REG_A2],
regs[REG_A3]);
break;
/* Number of parameters: 4 */
case 4:
ret = g_stublookup[index].stub4(regs[REG_A1], regs[REG_A2],
regs[REG_A3], regs[REG_T0]);
break;
/* Number of parameters: 5 */
case 5:
ret = g_stublookup[index].stub5(regs[REG_A1], regs[REG_A2],
regs[REG_A3], regs[REG_T0],
regs[REG_T1]);
break;
/* Number of parameters: 6 */
case 6:
ret = g_stublookup[index].stub6(regs[REG_A1], regs[REG_A2],
regs[REG_A3], regs[REG_T0],
regs[REG_T1], regs[REG_T2]);
break;
/* Unsupported number of paramters. Report error and return ERROR */
default:
slldbg("ERROR: Bad SYS call %d number parameters %d\n",
cmd, g_stubnparms[index]);
break;
}
#ifdef SYSCALL_INTERRUPTIBLE
irqdisable();
#endif
}
/* Set up the return vaue. First, check if a context switch occurred.
* In this case, regs will no longer be the same as current_regs. In
* the case of a context switch, we will have to save the return value
* in the TCB where it can be returned later when the task is restarted.
*/
if (regs != current_regs)
{
regs = rtcb->xcp.regs;
}
/* Then return the result in v0 */
swidbg("Return value regs: %p value: %d\n", regs, ret);
regs[REG_v0] = (uint32_t)ret;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_swint0
*
* Description:
* This is software interrupt 0 exception handler that performs context
* switching and manages system calls
*
****************************************************************************/
int up_swint0(int irq, FAR void *context)
{
uint32_t *regs = (uint32_t*)context;
uint32_t cause;
DEBUGASSERT(regs && regs == current_regs);
/* Software interrupt 0 is invoked with REG_A0 (REG_R4) = system call
* command and REG_A1-3 and REG_T0-2 (REG_R5-10) = variable number of
* arguments depending on the system call.
*/
#ifdef DEBUG_SWINT0
swidbg("Entry: regs: %p cmd: %d\n", regs, regs[REG_R4]);
up_registerdump(regs);
#endif
/* Handle the SWInt according to the command in $4 */
switch (regs[REG_R4])
{
/* R4=SYS_restore_context: This a restore context command:
*
* void up_fullcontextrestore(uint32_t *restoreregs) __attribute__ ((noreturn));
*
* At this point, the following values are saved in context:
*
* R4 = SYS_restore_context
* R5 = restoreregs
*
* In this case, we simply need to set current_regs to restore register
* area referenced in the saved R1. context == current_regs is the normal
* exception return. By setting current_regs = context[R1], we force
* the return to the saved context referenced in R1.
*/
case SYS_restore_context:
{
DEBUGASSERT(regs[REG_A1] != 0);
current_regs = (uint32_t*)regs[REG_A1];
}
break;
/* R4=SYS_switch_context: This a switch context command:
*
* void up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs);
*
* At this point, the following values are saved in context:
*
* R4 = SYS_switch_context
* R5 = saveregs
* R6 = restoreregs
*
* In this case, we save the context registers to the save register
* area reference by the saved contents of R5 and then set
* current_regs to to the save register area referenced by the saved
* contents of R6.
*/
case SYS_switch_context:
{
DEBUGASSERT(regs[REG_A1] != 0 && regs[REG_A2] != 0);
up_copystate((uint32_t*)regs[REG_A1], regs);
current_regs = (uint32_t*)regs[REG_A2];
}
break;
/* This is not an architecture-specify system call. If NuttX is built
* as a standalone kernel with a system call interface, then all of the
* additional system calls must be handled as in the default case.
*/
default:
#ifdef CONFIG_NUTTX_KERNEL
dispatch_syscall(regs);
#else
slldbg("ERROR: Bad SYS call: %d\n", regs[REG_A0]);
#endif
break;
}
/* Report what happened. That might difficult in the case of a context switch */
#ifdef DEBUG_SWINT0
if (regs != current_regs)
{
swidbg("SWInt Return: Context switch!\n");
up_registerdump(current_regs);
}
else
{
swidbg("SWInt Return: %d\n", regs[REG_V0]);
}
#endif
/* Clear the pending software interrupt 0 in the PIC32 interrupt block */
up_clrpend_irq(PIC32MX_IRQSRC_CS0);
/* And reset the software interrupt bit in the MIPS CAUSE register */
cause = cp0_getcause();
cause &= ~CP0_CAUSE_IP0;
cp0_putcause(cause);
return OK;
}
