/****************************************************************************
* arch/mips/src/mips32/up_swint0.c
*
* Copyright (C) 2011-2012 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 ************************************************************/
/* 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_SYSCALL
*/
#ifdef CONFIG_DEBUG_SYSCALL
# define swidbg(format, ...) lldbg(format, ##__VA_ARGS__)
#else
# define swidbg(x...)
#endif
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: up_registerdump
****************************************************************************/
#ifdef CONFIG_DEBUG_SYSCALL
static void up_registerdump(const 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:
* Call the stub function corresponding to the system call.
*
****************************************************************************/
#ifdef CONFIG_BUILD_KERNEL
static void dispatch_syscall(void) naked_function;
static void dispatch_syscall(void)
{
# error "Missing logic"
/* Refer to arch/arm/src/armv7-m/up_svcall.h for how this is done for ARM */
/* __asm__ __volatile__ */
/* ( */
/* Save registers */
/* Get the base of the stub lookup table */
/* Get the offset of the stub for this syscall */
/* Load the entry of the stub for this syscall */
/* Call the stub */
/* Restore regsisters */
/* Return from the syscall */
/* ); */
}
#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 CONFIG_DEBUG_SYSCALL
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) noreturn_function;
*
* 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;
/* R0=SYS_syscall_return: This a switch context command:
*
* void up_sycall_return(void);
*
* At this point, the following values are saved in context:
*
* R0 = SYS_syscall_return
*
* We need to restore the saved return address and return in
* unprivileged thread mode.
*/
#ifdef CONFIG_BUILD_KERNEL
case SYS_syscall_return:
{
struct tcb_s *rtcb = sched_self();
int index = (int)rtcb->xcp.nsyscalls - 1;
/* Make sure that there is a saved syscall return address. */
DEBUGASSERT(index >= 0);
/* Setup to return to the saved syscall return address in
* the original mode.
*/
current_regs[REG_EPC] = rtcb->xcp.syscall[index].sysreturn;
#error "Missing logic -- need to restore the original mode"
rtcb->xcp.nsyscalls = index;
}
break;
#endif
/* 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_BUILD_KERNEL
FAR struct tcb_s *rtcb = sched_self();
int index = rtcb->xcp.nsyscalls;
/* Verify that the SYS call number is within range */
DEBUGASSERT(current_regs[REG_A0] < SYS_maxsyscall);
/* Make sure that we got here that there is a no saved syscall
* return address. We cannot yet handle nested system calls.
*/
DEBUGASSERT(index < CONFIG_SYS_NNEST);
/* Setup to return to dispatch_syscall in privileged mode. */
rtcb->xcpsyscall[index].sysreturn = regs[REG_EPC];
#error "Missing logic -- Need to save mode"
rtcb->xcp.nsyscalls = index + 1;
regs[REG_EPC] = (uint32_t)dispatch_syscall;
#error "Missing logic -- Need to set privileged mode"
/* Offset R0 to account for the reserved values */
current_regs[REG_R0] -= CONFIG_SYS_RESERVED;
#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 CONFIG_DEBUG_SYSCALL
if (regs != current_regs)
{
swidbg("SWInt Return: Context switch!\n");
up_registerdump((const uint32_t*)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;
}
