From bc659336257788ea1ceb787b5512dc40374e9e76 Mon Sep 17 00:00:00 2001 From: Glenn Anderson Date: Mon, 14 Mar 2022 12:43:57 -0700 Subject: [PATCH] Optimize handling of reset interrupt. --- src/BlueSCSI.cpp | 117 ++++++++++++++++++++++++++++++++--------------- 1 file changed, 80 insertions(+), 37 deletions(-) diff --git a/src/BlueSCSI.cpp b/src/BlueSCSI.cpp index af13c9c..321e342 100644 --- a/src/BlueSCSI.cpp +++ b/src/BlueSCSI.cpp @@ -37,6 +37,7 @@ #include // For Platform.IO #include +#include #ifdef USE_STM32_DMA #warning "warning USE_STM32_DMA" @@ -187,6 +188,8 @@ HDDIMG img[NUM_SCSIID][NUM_SCSILUN]; // Maximum number uint8_t m_senseKey = 0; // Sense key unsigned m_addition_sense = 0; // Additional sense information volatile bool m_isBusReset = false; // Bus reset +volatile bool m_resetJmp = false; // Call longjmp on reset +jmp_buf m_resetJmpBuf; byte scsi_id_mask; // Mask list of responding SCSI IDs byte m_id; // Currently responding SCSI-ID @@ -416,7 +419,7 @@ void setup() SCSI_TARGET_INACTIVE() //Occurs when the RST pin state changes from HIGH to LOW - //attachInterrupt(PIN_MAP[RST].gpio_bit, onBusReset, FALLING); + //attachInterrupt(RST, onBusReset, FALLING); LED_ON(); @@ -519,7 +522,7 @@ void setup() finalizeFileLog(); LED_OFF(); //Occurs when the RST pin state changes from HIGH to LOW - attachInterrupt(PIN_MAP[RST].gpio_bit, onBusReset, FALLING); + attachInterrupt(RST, onBusReset, FALLING); } /* @@ -612,6 +615,36 @@ void noSDCardFound(void) } } +/* + * Return from exception and call longjmp + */ +void __attribute__ ((noinline)) longjmpFromInterrupt(jmp_buf jmpb, int retval) __attribute__ ((noreturn)); +void longjmpFromInterrupt(jmp_buf jmpb, int retval) { + // Address of longjmp with the thumb bit cleared + const uint32_t longjmpaddr = ((uint32_t)longjmp) & 0xfffffffe; + const uint32_t zero = 0; + // Default PSR value, function calls don't require any particular value + const uint32_t PSR = 0x01000000; + // For documentation on what this is doing, see: + // https://developer.arm.com/documentation/dui0552/a/the-cortex-m3-processor/exception-model/exception-entry-and-return + // Stack frame needs to have R0-R3, R12, LR, PC, PSR (from bottom to top) + // This is being set up to have R0 and R1 contain the parameters passed to longjmp, and PC is the address of the longjmp function. + // This is using existing stack space, rather than allocating more, as longjmp is just going to unroll the stack even further. + // 0xfffffff9 is the EXC_RETURN value to return to thread mode. + asm ( + "str %0, [sp];\ + str %1, [sp, #4];\ + str %2, [sp, #8];\ + str %2, [sp, #12];\ + str %2, [sp, #16];\ + str %2, [sp, #20];\ + str %3, [sp, #24];\ + str %4, [sp, #28];\ + ldr lr, =0xfffffff9" + :: "r"(jmpb),"r"(retval),"r"(zero), "r"(longjmpaddr), "r"(PSR) + ); +} + /* * Bus reset interrupt. */ @@ -635,10 +668,28 @@ void onBusReset(void) SCSI_DB_INPUT() LOGN("BusReset!"); - m_isBusReset = true; + if (m_resetJmp) { + m_resetJmp = false; + // Jumping out of the interrupt handler, so need to clear the interupt source. + uint8 exti = PIN_MAP[RST].gpio_bit; + EXTI_BASE->PR = (1U << exti); + longjmpFromInterrupt(m_resetJmpBuf, 1); + } else { + m_isBusReset = true; + } } } } + +/* + * Enable the reset longjmp, and check if reset fired while it was disabled. + */ +void enableResetJmp(void) { + m_resetJmp = true; + if (m_isBusReset) { + longjmp(m_resetJmpBuf, 1); + } +} /* * Read by handshake. @@ -647,10 +698,10 @@ inline byte readHandshake(void) { SCSI_OUT(vREQ,active) //SCSI_DB_INPUT() - while( ! SCSI_IN(vACK)) { if(m_isBusReset) return 0; } + while( ! SCSI_IN(vACK)); byte r = readIO(); SCSI_OUT(vREQ,inactive) - while( SCSI_IN(vACK)) { if(m_isBusReset) return 0; } + while( SCSI_IN(vACK)); return r; } @@ -667,12 +718,12 @@ inline void writeHandshake(byte d) SCSI_OUT(vREQ,inactive) // setup wait (30ns) SCSI_OUT(vREQ,active) // (30ns) //while(!SCSI_IN(vACK)) { if(m_isBusReset){ SCSI_DB_INPUT() return; }} - while(!m_isBusReset && !SCSI_IN(vACK)); + while(!SCSI_IN(vACK)); // ACK.Fall to REQ.Raise delay 500ns(typ.) (DTC-510B) GPIOB->regs->BSRR = DBP(0xff); // DB=0xFF , SCSI_OUT(vREQ,inactive) // REQ.Raise to DB hold time 0ns SCSI_DB_INPUT() // (150ns) - while( SCSI_IN(vACK)) { if(m_isBusReset) return; } + while( SCSI_IN(vACK)); } /* @@ -686,9 +737,6 @@ void writeDataPhase(int len, const byte* p) SCSI_OUT(vCD ,inactive) // gpio_write(CD, low); SCSI_OUT(vIO , active) // gpio_write(IO, high); for (int i = 0; i < len; i++) { - if(m_isBusReset) { - return; - } writeHandshake(p[i]); } } @@ -709,7 +757,9 @@ void writeDataPhaseSD(uint32_t adds, uint32_t len) for(uint32_t i = 0; i < len; i++) { // Asynchronous reads will make it faster ... + m_resetJmp = false; m_img->m_file.read(m_buf, m_img->m_blocksize); + enableResetJmp(); #if READ_SPEED_OPTIMIZE @@ -718,8 +768,8 @@ void writeDataPhaseSD(uint32_t adds, uint32_t len) #define FETCH_SRC() (src_byte = *srcptr++) #define FETCH_BSRR_DB() (bsrr_val = bsrr_tbl[src_byte]) #define REQ_OFF_DB_SET(BSRR_VAL) *db_dst = BSRR_VAL -#define WAIT_ACK_ACTIVE() while(!m_isBusReset && !SCSI_IN(vACK)) -#define WAIT_ACK_INACTIVE() do{ if(m_isBusReset) return; }while(SCSI_IN(vACK)) +#define WAIT_ACK_ACTIVE() while(!SCSI_IN(vACK)) +#define WAIT_ACK_INACTIVE() while(SCSI_IN(vACK)) SCSI_DB_OUTPUT() register byte *srcptr= m_buf; // Source buffer @@ -799,9 +849,6 @@ void writeDataPhaseSD(uint32_t adds, uint32_t len) SCSI_DB_INPUT() #else for(int j = 0; j < m_img->m_blocksize; j++) { - if(m_isBusReset) { - return; - } writeHandshake(m_buf[j]); } #endif @@ -835,6 +882,7 @@ void readDataPhaseSD(uint32_t adds, uint32_t len) SCSI_OUT(vCD ,inactive) // gpio_write(CD, low); SCSI_OUT(vIO ,inactive) // gpio_write(IO, low); for(uint32_t i = 0; i < len; i++) { + m_resetJmp = true; #if WRITE_SPEED_OPTIMIZE register byte *dstptr= m_buf; register byte *endptr= m_buf + m_img->m_blocksize; @@ -848,21 +896,21 @@ void readDataPhaseSD(uint32_t adds, uint32_t len) dstptr[5] = readHandshake(); dstptr[6] = readHandshake(); dstptr[7] = readHandshake(); - if(m_isBusReset) { - return; - } } #else for(int j = 0; j < m_img->m_blocksize; j++) { - if(m_isBusReset) { - return; - } m_buf[j] = readHandshake(); } #endif + m_resetJmp = false; m_img->m_file.write(m_buf, m_img->m_blocksize); + // If a reset happened while writing, break and let the flush happen before it is handled. + if (m_isBusReset) { + break; + } } m_img->m_file.flush(); + enableResetJmp(); } /* @@ -1235,6 +1283,11 @@ void loop() } LOGN("Selection"); m_isBusReset = false; + if (setjmp(m_resetJmpBuf) == 1) { + LOGN("Reset, going to BusFree"); + goto BusFree; + } + enableResetJmp(); // Set BSY to-when selected SCSI_BSY_ACTIVE(); // Turn only BSY output ON, ACTIVE @@ -1243,9 +1296,6 @@ void loop() // Wait until SEL becomes inactive while(isHigh(gpio_read(SEL)) && isLow(gpio_read(BSY))) { - if(m_isBusReset) { - goto BusFree; - } } SCSI_TARGET_ACTIVE() // (BSY), REQ, MSG, CD, IO output turned on // @@ -1308,22 +1358,21 @@ void loop() int len; byte cmd[12]; - cmd[0] = readHandshake(); if(m_isBusReset) goto BusFree; + cmd[0] = readHandshake(); LOGHEX(cmd[0]); // Command length selection, reception static const int cmd_class_len[8]={6,10,10,6,6,12,6,6}; len = cmd_class_len[cmd[0] >> 5]; - cmd[1] = readHandshake(); LOG(":");LOGHEX(cmd[1]); if(m_isBusReset) goto BusFree; - cmd[2] = readHandshake(); LOG(":");LOGHEX(cmd[2]); if(m_isBusReset) goto BusFree; - cmd[3] = readHandshake(); LOG(":");LOGHEX(cmd[3]); if(m_isBusReset) goto BusFree; - cmd[4] = readHandshake(); LOG(":");LOGHEX(cmd[4]); if(m_isBusReset) goto BusFree; - cmd[5] = readHandshake(); LOG(":");LOGHEX(cmd[5]); if(m_isBusReset) goto BusFree; + cmd[1] = readHandshake(); LOG(":");LOGHEX(cmd[1]); + cmd[2] = readHandshake(); LOG(":");LOGHEX(cmd[2]); + cmd[3] = readHandshake(); LOG(":");LOGHEX(cmd[3]); + cmd[4] = readHandshake(); LOG(":");LOGHEX(cmd[4]); + cmd[5] = readHandshake(); LOG(":");LOGHEX(cmd[5]); // Receive the remaining commands for(int i = 6; i < len; i++ ) { cmd[i] = readHandshake(); LOG(":"); LOGHEX(cmd[i]); - if(m_isBusReset) goto BusFree; } // LUN confirmation m_sts = cmd[1]&0xe0; // Preset LUN in status byte @@ -1422,18 +1471,12 @@ void loop() m_addition_sense = 0x2000; // Invalid Command Operation Code break; } - if(m_isBusReset) { - goto BusFree; - } LOGN("Sts"); SCSI_OUT(vMSG,inactive) // gpio_write(MSG, low); SCSI_OUT(vCD , active) // gpio_write(CD, high); SCSI_OUT(vIO , active) // gpio_write(IO, high); writeHandshake(m_sts); - if(m_isBusReset) { - goto BusFree; - } LOGN("MsgIn"); SCSI_OUT(vMSG, active) // gpio_write(MSG, high);