Gate controller pairing behind BOOTSEL

bootsel_pairing_button.cpp

@@ -0,0 +1,99 @@
+#include "bootsel_pairing_button.h"
+
+#include "hardware/gpio.h"
+#include "hardware/structs/ioqspi.h"
+#include "hardware/structs/sio.h"
+#include "pico/flash.h"
+#include "pico/time.h"
+#if PICO_RP2350
+#include "hardware/regs/sio.h"
+#endif
+
+namespace {
+
+constexpr uint32_t kPollIntervalMs = 100;
+constexpr uint32_t kFlashSafeTimeoutMs = 100;
+constexpr uint32_t kQspiCsPinIndex = 1;
+
+BootselPairingButtonHoldFsm g_hold_fsm;
+uint32_t g_last_sample_ms = 0;
+
+// QSPI CSn sampling adapted from awalol/DS5Dongle's button_functions.cpp:
+// https://github.com/awalol/DS5Dongle/blob/master/src/button_functions.cpp
+// Copyright (c) 2026 awalol; used under the MIT License.
+//
+// This callback and everything it executes while CSn is floated must remain in
+// SRAM or be an inlined hardware-register operation. In particular, do not add
+// logging or ordinary flash-backed data access here.
+void __no_inline_not_in_flash_func(read_bootsel_callback)(void* parameter) {
+    auto* pressed = static_cast<bool*>(parameter);
+
+    hw_write_masked(
+        &ioqspi_hw->io[kQspiCsPinIndex].ctrl,
+        GPIO_OVERRIDE_LOW << IO_QSPI_GPIO_QSPI_SS_CTRL_OEOVER_LSB,
+        IO_QSPI_GPIO_QSPI_SS_CTRL_OEOVER_BITS);
+
+    for (volatile uint32_t delay = 0; delay < 1000; ++delay) {
+    }
+
+#if PICO_RP2350
+    *pressed =
+        (sio_hw->gpio_hi_in & SIO_GPIO_HI_IN_QSPI_CSN_BITS) == 0;
+#else
+    *pressed = (sio_hw->gpio_hi_in & (1u << kQspiCsPinIndex)) == 0;
+#endif
+
+    hw_write_masked(
+        &ioqspi_hw->io[kQspiCsPinIndex].ctrl,
+        GPIO_OVERRIDE_NORMAL << IO_QSPI_GPIO_QSPI_SS_CTRL_OEOVER_LSB,
+        IO_QSPI_GPIO_QSPI_SS_CTRL_OEOVER_BITS);
+}
+
+BootselPairingButtonSample sample_bootsel() {
+    bool pressed = false;
+    const int result = flash_safe_execute(read_bootsel_callback, &pressed,
+                                          kFlashSafeTimeoutMs);
+    if (result != PICO_OK) {
+        return BootselPairingButtonSample::kUnread;
+    }
+    return pressed ? BootselPairingButtonSample::kPressed
+                   : BootselPairingButtonSample::kReleased;
+}
+
+}  // namespace
+
+bool BootselPairingButtonHoldFsm::update(
+    BootselPairingButtonSample sample) {
+    if (sample == BootselPairingButtonSample::kUnread) {
+        return false;
+    }
+
+    if (sample == BootselPairingButtonSample::kReleased) {
+        pressed_samples_ = 0;
+        hold_reported_ = false;
+        return false;
+    }
+
+    if (hold_reported_) {
+        return false;
+    }
+
+    ++pressed_samples_;
+    if (pressed_samples_ < kHoldSamples) {
+        return false;
+    }
+
+    hold_reported_ = true;
+    return true;
+}
+
+bool bootsel_pairing_button_task() {
+    const uint32_t now_ms =
+        static_cast<uint32_t>(to_ms_since_boot(get_absolute_time()));
+    if (now_ms - g_last_sample_ms < kPollIntervalMs) {
+        return false;
+    }
+    g_last_sample_ms = now_ms;
+
+    return g_hold_fsm.update(sample_bootsel());
+}