Support IRQ disabled SPI transactions (#1714)

Fixes #1147

When SPI.beginTransaction() is called, disable all GPIO IRQs that were
registered using SPI.usingInterrupt().  On SPI.endTransaction(), restore
all the IRQs to their prior state.

Author: earlephilhower

libraries/SPI/keywords.txt

@@ -14,6 +14,9 @@ SPI1	KEYWORD1
 #######################################
 begin	KEYWORD2
 end	KEYWORD2
+beginTransaction	KEYWORD2
+endTransaction	KEYWORD2
+SPISettings	KEYWORD2
 transfer	KEYWORD2
 setBitOrder	KEYWORD2
 setDataMode	KEYWORD2

libraries/SPI/src/SPI.cpp

@@ -21,6 +21,8 @@
 #include "SPI.h"
 #include <hardware/spi.h>
 #include <hardware/gpio.h>
+#include <hardware/structs/iobank0.h>
+#include <hardware/irq.h>
 
 #ifdef USE_TINYUSB
 // For Serial when selecting TinyUSB.  Can't include in the core because Arduino IDE
@@ -191,10 +193,33 @@ void SPIClassRP2040::beginTransaction(SPISettings settings) {
         DEBUGSPI("SPI: actual baudrate=%u\n", spi_get_baudrate(_spi));
         _initted = true;
     }
+    // Disable any IRQs that are being used for SPI
+    io_irq_ctrl_hw_t *irq_ctrl_base = get_core_num() ? &iobank0_hw->proc1_irq_ctrl : &iobank0_hw->proc0_irq_ctrl;
+    DEBUGSPI("SPI: IRQ masks before = %08x %08x %08x %08x\n", (unsigned)irq_ctrl_base->inte[0], (unsigned)irq_ctrl_base->inte[1], (unsigned)irq_ctrl_base->inte[2], (unsigned)irq_ctrl_base->inte[3]);
+    for (auto entry : _usingIRQs) {
+        int gpio = entry.first;
+
+        // There is no gpio_get_irq, so manually twiddle the register
+        io_rw_32 *en_reg = &irq_ctrl_base->inte[gpio / 8];
+        uint32_t val = ((*en_reg) >> (4 * (gpio % 8))) & 0xf;
+        _usingIRQs.insert_or_assign(gpio, val);
+        DEBUGSPI("SPI: GPIO %d = %d\n", gpio, val);
+        (*en_reg) ^= val << (4 * (gpio % 8));
+    }
+    DEBUGSPI("SPI: IRQ masks after = %08x %08x %08x %08x\n", (unsigned)irq_ctrl_base->inte[0], (unsigned)irq_ctrl_base->inte[1], (unsigned)irq_ctrl_base->inte[2], (unsigned)irq_ctrl_base->inte[3]);
 }
 
 void SPIClassRP2040::endTransaction(void) {
     DEBUGSPI("SPI::endTransaction()\n");
+    // Re-enablke IRQs
+    for (auto entry : _usingIRQs) {
+        int gpio = entry.first;
+        int mode = entry.second;
+        gpio_set_irq_enabled(gpio, mode, true);
+    }
+    io_irq_ctrl_hw_t *irq_ctrl_base = get_core_num() ? &iobank0_hw->proc1_irq_ctrl : &iobank0_hw->proc0_irq_ctrl;
+    (void) irq_ctrl_base;
+    DEBUGSPI("SPI: IRQ masks = %08x %08x %08x %08x\n", (unsigned)irq_ctrl_base->inte[0], (unsigned)irq_ctrl_base->inte[1], (unsigned)irq_ctrl_base->inte[2], (unsigned)irq_ctrl_base->inte[3]);
 }
 
 bool SPIClassRP2040::setRX(pin_size_t pin) {
@@ -292,6 +317,7 @@ void SPIClassRP2040::begin(bool hwCS) {
     gpio_set_function(_TX, GPIO_FUNC_SPI);
     // Give a default config in case user doesn't use beginTransaction
     beginTransaction(_spis);
+    endTransaction();
 }
 
 void SPIClassRP2040::end() {
@@ -312,11 +338,13 @@ void SPIClassRP2040::end() {
 void SPIClassRP2040::setBitOrder(BitOrder order) {
     _spis = SPISettings(_spis.getClockFreq(), order, _spis.getDataMode());
     beginTransaction(_spis);
+    endTransaction();
 }
 
 void SPIClassRP2040::setDataMode(uint8_t uc_mode) {
     _spis = SPISettings(_spis.getClockFreq(), _spis.getBitOrder(), uc_mode);
     beginTransaction(_spis);
+    endTransaction();
 }
 
 void SPIClassRP2040::setClockDivider(uint8_t uc_div) {

libraries/SPI/src/SPI.h

@@ -23,6 +23,7 @@
 #include <Arduino.h>
 #include <api/HardwareSPI.h>
 #include <hardware/spi.h>
+#include <map>
 
 class SPIClassRP2040 : public arduino::HardwareSPI {
 public:
@@ -62,10 +63,10 @@ class SPIClassRP2040 : public arduino::HardwareSPI {
 
     // Unimplemented
     virtual void usingInterrupt(int interruptNumber) override {
-        (void) interruptNumber;
+        _usingIRQs.insert({interruptNumber, 0});
     }
     virtual void notUsingInterrupt(int interruptNumber) override {
-        (void) interruptNumber;
+        _usingIRQs.erase(interruptNumber);
     }
     virtual void attachInterrupt() override { /* noop */ }
     virtual void detachInterrupt() override { /* noop */ }
@@ -83,6 +84,8 @@ class SPIClassRP2040 : public arduino::HardwareSPI {
     bool _hwCS;
     bool _running; // SPI port active
     bool _initted; // Transaction begun
+
+    std::map<int, int> _usingIRQs;
 };
 
 extern SPIClassRP2040 SPI;