// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <stdlib.h>

#include <xtensa/config/core.h>

#include "rom/rtc.h"

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/xtensa_api.h"

#include "soc/uart_reg.h"
#include "soc/io_mux_reg.h"
#include "soc/dport_reg.h"
#include "soc/rtc_cntl_reg.h"
#include "soc/timer_group_struct.h"
#include "soc/timer_group_reg.h"

#include "esp_gdbstub.h"
#include "esp_panic.h"


/*
Panic handlers; these get called when an unhandled exception occurs or the assembly-level
task switching / interrupt code runs into an unrecoverable error. The default task stack
overflow handler also is in here.
*/

#if !CONFIG_FREERTOS_PANIC_SILENT_REBOOT
//printf may be broken, so we fix our own printing fns...
inline static void panicPutchar(char c) {
	while (((READ_PERI_REG(UART_STATUS_REG(0))>>UART_TXFIFO_CNT_S)&UART_TXFIFO_CNT)>=126) ;
	WRITE_PERI_REG(UART_FIFO_REG(0), c);
}

inline static void panicPutStr(const char *c) {
	int x=0;
	while (c[x]!=0) {
		panicPutchar(c[x]);
		x++;
	}
}

inline static void panicPutHex(int a) {
	int x;
	int c;
	panicPutchar(' ');
	for (x=0; x<8; x++) {
		c=(a>>28)&0xf;
		if (c<10) panicPutchar('0'+c); else panicPutchar('a'+c-10);
		a<<=4;
	}
}

inline static void panicPutDec(int a) {
	int n1, n2;
	n1=a%10;
	n2=a/10;
	panicPutchar(' ');
	if (n2==0) panicPutchar(' '); else panicPutchar(n2+'0');
	panicPutchar(n1+'0');
}
#else
//No printing wanted. Stub out these functions.
inline static void panicPutchar(char c) { }
inline static void panicPutStr(const char *c) { }
inline static void panicPutHex(int a) { }
inline static void panicPutDec(int a) { }
#endif


void  __attribute__((weak)) vApplicationStackOverflowHook( TaskHandle_t xTask, signed char *pcTaskName ) {
	panicPutStr("***ERROR*** A stack overflow in task ");
	panicPutStr((char*)pcTaskName);
	panicPutStr(" has been detected.\r\n");
}

static const char *edesc[]={
		"IllegalInstruction", "Syscall", "InstructionFetchError", "LoadStoreError",
		"Level1Interrupt", "Alloca", "IntegerDivideByZero", "PCValue",
		"Privileged", "LoadStoreAlignment", "res", "res",
		"InstrPDAddrError", "LoadStorePIFDataError", "InstrPIFAddrError", "LoadStorePIFAddrError",
		"InstTLBMiss", "InstTLBMultiHit", "InstFetchPrivilege", "res",
		"InstrFetchProhibited", "res", "res", "res",
		"LoadStoreTLBMiss", "LoadStoreTLBMultihit", "LoadStorePrivilege", "res",
		"LoadProhibited", "StoreProhibited", "res", "res",
		"Cp0Dis", "Cp1Dis", "Cp2Dis", "Cp3Dis",
		"Cp4Dis", "Cp5Dis", "Cp6Dis", "Cp7Dis"
	};


void commonErrorHandler(XtExcFrame *frame);

//The fact that we've panic'ed probably means the other CPU is now running wild, possibly
//messing up the serial output, so we kill it here.
static void haltOtherCore() {
	if (xPortGetCoreID()==0) {
		//Kill app cpu
		CLEAR_PERI_REG_MASK(RTC_CNTL_SW_CPU_STALL_REG, RTC_CNTL_SW_STALL_APPCPU_C1_M);
		SET_PERI_REG_MASK(RTC_CNTL_SW_CPU_STALL_REG, 0x21<<RTC_CNTL_SW_STALL_APPCPU_C1_S);
		CLEAR_PERI_REG_MASK(RTC_CNTL_OPTIONS0_REG, RTC_CNTL_SW_STALL_APPCPU_C0_M);
		SET_PERI_REG_MASK(RTC_CNTL_OPTIONS0_REG, 2<<RTC_CNTL_SW_STALL_APPCPU_C0_S);
	} else {
		//Kill pro cpu
		CLEAR_PERI_REG_MASK(RTC_CNTL_SW_CPU_STALL_REG, RTC_CNTL_SW_STALL_PROCPU_C1_M);
		SET_PERI_REG_MASK(RTC_CNTL_SW_CPU_STALL_REG, 0x21<<RTC_CNTL_SW_STALL_PROCPU_C1_S);
		CLEAR_PERI_REG_MASK(RTC_CNTL_OPTIONS0_REG, RTC_CNTL_SW_STALL_PROCPU_C0_M);
		SET_PERI_REG_MASK(RTC_CNTL_OPTIONS0_REG, 2<<RTC_CNTL_SW_STALL_PROCPU_C0_S);
	}
}

//Returns true when a debugger is attached using JTAG.
static int inOCDMode() {
#if CONFIG_FREERTOS_DEBUG_OCDAWARE
	int dcr;
	int reg=0x10200C; //DSRSET register
	asm("rer %0,%1":"=r"(dcr):"r"(reg));
	return (dcr&0x1);
#else
	return 0; //Always return no debugger is attached.
#endif
}

void panicHandler(XtExcFrame *frame) {
	int *regs=(int*)frame;
	//Please keep in sync with PANIC_RSN_* defines
	const char *reasons[]={
			"Unknown reason",
			"Unhandled debug exception",
			"Double exception",
			"Unhandled kernel exception",
			"Coprocessor exception",
			"Interrupt wdt timeout on CPU0",
			"Interrupt wdt timeout on CPU1",
		};
	const char *reason=reasons[0];
	//The panic reason is stored in the EXCCAUSE register.
	if (regs[20]<=PANIC_RSN_MAX) reason=reasons[regs[20]];
	haltOtherCore();
	panicPutStr("Guru Meditation Error: Core ");
	panicPutDec(xPortGetCoreID());
	panicPutStr(" panic'ed (");
	panicPutStr(reason);
	panicPutStr(")\r\n");

	if (inOCDMode()) {
		asm("break.n 1");
	}
	commonErrorHandler(frame);
}

static void setFirstBreakpoint(uint32_t pc) {
	asm(
		"wsr.ibreaka0 %0\n" \
		"rsr.ibreakenable a3\n" \
		"movi a4,1\n" \
		"or a4, a4, a3\n" \
		"wsr.ibreakenable a4\n" \
		::"r"(pc):"a3","a4");
}

void xt_unhandled_exception(XtExcFrame *frame) {
	int *regs=(int*)frame;
	int x;

	haltOtherCore();
	panicPutStr("Guru Meditation Error of type ");
	x=regs[20];
	if (x<40) panicPutStr(edesc[x]); else panicPutStr("Unknown");
	panicPutStr(" occurred on core ");
	panicPutDec(xPortGetCoreID());
	if (inOCDMode()) {
		panicPutStr(" at pc=");
		panicPutHex(regs[1]);
		panicPutStr(". Setting bp and returning..\r\n");
		//Stick a hardware breakpoint on the address the handler returns to. This way, the OCD debugger
		//will kick in exactly at the context the error happened.
		setFirstBreakpoint(regs[1]);
		return;
	}
	panicPutStr(". Exception was unhandled.\r\n");
	commonErrorHandler(frame);
}


/*
If watchdogs are enabled, the panic handler runs the risk of getting aborted pre-emptively because
an overzealous watchdog decides to reset it. On the other hand, if we disable all watchdogs, we run
the risk of somehow halting in the panic handler and not resetting. That is why this routine kills 
all watchdogs except the timer group 0 watchdog, and it reconfigures that to reset the chip after
one second.
*/
static void reconfigureAllWdts() {
	TIMERG0.wdt_wprotect=WDT_WRITE_KEY;
	TIMERG0.wdt_feed=1;
	TIMERG0.wdt_config0.sys_reset_length=7;				//3.2uS
	TIMERG0.wdt_config0.cpu_reset_length=7;				//3.2uS
	TIMERG0.wdt_config0.stg0=3;							//1st stage timeout: reset system
	TIMERG0.wdt_config1.clk_prescale=80*500;			//Prescaler: wdt counts in ticks of 0.5mS
	TIMERG0.wdt_config2=2000;							//1 second before reset
	TIMERG0.wdt_config0.en=1;
	TIMERG0.wdt_wprotect=0;
	//Disable wdt 1
	TIMERG1.wdt_wprotect=WDT_WRITE_KEY;
	TIMERG1.wdt_config0.en=0;
	TIMERG1.wdt_wprotect=0;
}

/*
This disables all the watchdogs for when we call the gdbstub.
*/
static void disableAllWdts() {
	TIMERG0.wdt_wprotect=WDT_WRITE_KEY;
	TIMERG0.wdt_config0.en=0;
	TIMERG0.wdt_wprotect=0;
	TIMERG1.wdt_wprotect=WDT_WRITE_KEY;
	TIMERG1.wdt_config0.en=0;
	TIMERG0.wdt_wprotect=0;
}


/*
We arrive here after a panic or unhandled exception, when no OCD is detected. Dump the registers to the
serial port and either jump to the gdb stub, halt the CPU or reboot.
*/
void commonErrorHandler(XtExcFrame *frame) {
	int *regs=(int*)frame;
	int x, y;
	const char *sdesc[]={
		"PC      ","PS      ","A0      ","A1      ","A2      ","A3      ","A4      ","A5      ",
		"A6      ","A7      ","A8      ","A9      ","A10     ","A11     ","A12     ","A13     ",
		"A14     ","A15     ","SAR     ","EXCCAUSE","EXCVADDR","LBEG    ","LEND    ","LCOUNT  "};

	//Feed the watchdogs, so they will give us time to print out debug info
	reconfigureAllWdts();

	panicPutStr("Register dump:\r\n");

	for (x=0; x<24; x+=4) {
		for (y=0; y<4; y++) {
			if (sdesc[x+y][0]!=0) {
				panicPutStr(sdesc[x+y]);
				panicPutStr(": ");
				panicPutHex(regs[x+y+1]);
				panicPutStr("  ");
			}
		}
		panicPutStr("\r\n");
	}
#if CONFIG_FREERTOS_PANIC_GDBSTUB
	disableAllWdts();
	panicPutStr("Entering gdb stub now.\r\n");
	esp_gdbstub_panic_handler(frame);
#elif CONFIG_FREERTOS_PANIC_PRINT_REBOOT || CONFIG_FREERTOS_PANIC_SILENT_REBOOT
	panicPutStr("Rebooting...\r\n");
	for (x=0; x<100; x++) ets_delay_us(1000);
	software_reset();
#else
	disableAllWdts();
	panicPutStr("CPU halted.\r\n");
	while(1);
#endif
}


void esp_set_breakpoint_if_jtag(void *fn) {
	if (!inOCDMode()) return;
	setFirstBreakpoint((uint32_t)fn);
}