libhw: Add rp2040_gpioirq, use it

7 files changed, 141 insertions, 40 deletions

diff --git a/build-aux/lint-bin b/build-aux/lint-bin
index 0b955de..c487f36 100755
--- a/build-aux/lint-bin
+++ b/build-aux/lint-bin
@@ -25,7 +25,7 @@ RESET=$(tput sgr0)
 
 err() {
 	printf "${RED}%s${RESET}: %s\n" "$1" "$2" >&2
-	#r=1
+	r=1
 }
 
 # Input is `ld --print-map` format.
@@ -107,6 +107,21 @@ lint_stack() {
 		     <(readelf_funcs "$in_elffile" | sed 's/\.part\.[0-9]*$//' | sort -u))
 }
 
+lint_func_blocklist() {
+	local in_elffile
+	in_elffile=$1
+
+	local blocklist=(
+		gpio_default_irq_handler
+	)
+
+	while read -r func; do
+		err "$in_elffile" "Contains blocklisted function: ${func}"
+	done < <(readelf --syms --wide -- "$in_elffile" |
+			 awk '$4 == "FUNC" { print $8 }' |
+			 grep -Fx "${blocklist[@]/#/-e}")
+}
+
 main() {
 	r=0
 
@@ -116,7 +131,8 @@ main() {
 			echo 'Global variables:'
 			lint_globals "${elf}.map" | sed 's/^/  /'
 		} > "${elf%.elf}.lint.globals"
-		lint_stack "$elf" &> "${elf%.elf}.lint.stack"
+		(lint_stack "$elf") &> "${elf%.elf}.lint.stack"
+		lint_func_blocklist "$elf"
 	done
 
 	return $r
diff --git a/build-aux/stack.c.gen b/build-aux/stack.c.gen
index c73a8bb..66d837a 100755
--- a/build-aux/stack.c.gen
+++ b/build-aux/stack.c.gen
@@ -504,6 +504,7 @@ class LibHWPlugin:
             "rp2040_hwtimer_intrhandler",
             "hostclock_handle_sig_alarm",
             "hostnet_handle_sig_io",
+            "gpioirq_handler",
         ]
 
     def extra_nodes(self) -> typing.Collection[Node]:
@@ -522,6 +523,10 @@ class LibHWPlugin:
                     "w5500_udp_alarm_handler",
                 ]
             return ret, False
+        if "/rp2040_gpioirq.c:" in loc and "handler->fn" in line:
+            return [
+                "w5500_intrhandler",
+            ], False
         return None
 
     def skip_call(self, chain: list[str], call: str) -> bool:
@@ -711,17 +716,14 @@ class LibMiscPlugin:
 
 
 class PicoSDKPlugin:
-    app_gpio_handlers: typing.Collection[str]
     app_init_array: typing.Collection[str]
     app_preinit_array: typing.Collection[str]
 
     def __init__(
         self,
         *,
-        app_gpio_handlers: typing.Collection[str],
         app_init_array: typing.Collection[str],
     ) -> None:
-        self.app_gpio_handlers = app_gpio_handlers
         self.app_init_array = app_init_array
 
         # git grep '^PICO_RUNTIME_INIT_FUNC\S*('
@@ -754,7 +756,6 @@ class PicoSDKPlugin:
 
     def is_intrhandler(self, name: str) -> bool:
         return name in [
-            "gpio_default_irq_handler",
             "isr_invalid",
             "isr_nmi",
             "isr_hardfault",
@@ -783,8 +784,6 @@ class PicoSDKPlugin:
                 return ["rom_hword_as_ptr(BOOTROM_TABLE_LOOKUP_OFFSET)"], False
         if "/flash.c:" in loc and "boot2_copyout" in line:
             return ["_stage2_boot"], False
-        if "/gpio.c:" in loc and call == "callback":
-            return sorted(self.app_gpio_handlers), False
         if "/printf.c:" in loc:
             if call == "out":
                 return [
@@ -1137,10 +1136,6 @@ def main(
 
     lib9p_plugin = Lib9PPlugin(arg_base_dir, arg_c_fnames)
 
-    sbc_gpio_handlers = [
-        "w5500_intrhandler",
-    ]
-
     def sbc_is_thread(name: str) -> int:
         if name.endswith("_cr") and name != "lib9p_srv_read_cr":
             if "9p" in name:
@@ -1165,7 +1160,6 @@ def main(
     if arg_pico_platform == "rp2040":
         plugins += [
             PicoSDKPlugin(
-                app_gpio_handlers=sbc_gpio_handlers,
                 app_init_array=["register_fini"],
             ),
             TinyUSBDevicePlugin(arg_c_fnames),
diff --git a/cmd/sbc_harness/config/config.h b/cmd/sbc_harness/config/config.h
index b569cd5..f9c7df2 100644
--- a/cmd/sbc_harness/config/config.h
+++ b/cmd/sbc_harness/config/config.h
@@ -12,11 +12,6 @@
 /* W5500 **********************************************************************/
 
 /**
- * How many W5500 chips we have.
- */
-#define CONFIG_W5500_NUM                1
-
-/**
  * When allocating an arbitrary local port, what range should it be
  * allocated from?
  *
@@ -106,7 +101,7 @@ extern const size_t CONFIG_COROUTINE_STACK_SIZE_w5500_irq_cr;
 #define CONFIG_COROUTINE_NUM                   (                                 \
 	1                                             /* usb_common         */ + \
 	1                                             /* usb_keyboard       */ + \
-	CONFIG_W5500_NUM                              /* irq handler        */ + \
+	1                                             /* W5500 irq handler  */ + \
 	_CONFIG_9P_NUM_SOCKS                          /* 9P accept()+read() */ + \
 	(CONFIG_9P_SRV_MAX_REQS*_CONFIG_9P_NUM_SOCKS) /* 9P work+write()    */ )
 
diff --git a/libhw/CMakeLists.txt b/libhw/CMakeLists.txt
index d1767da..bd92e04 100644
--- a/libhw/CMakeLists.txt
+++ b/libhw/CMakeLists.txt
@@ -1,6 +1,6 @@
 # libhw/CMakeLists.txt - Device drivers
 #
-# Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 add_library(libhw INTERFACE)
@@ -14,8 +14,9 @@ if (PICO_PLATFORM STREQUAL "rp2040")
 		libcr_ipc
 	)
 	target_sources(libhw INTERFACE
-		rp2040_hwtimer.c
+		rp2040_gpioirq.c
 		rp2040_hwspi.c
+		rp2040_hwtimer.c
 		w5500.c
 	)
 	target_link_libraries(libhw INTERFACE
diff --git a/libhw/rp2040_gpioirq.c b/libhw/rp2040_gpioirq.c
new file mode 100644
index 0000000..2f0ceac
--- /dev/null
+++ b/libhw/rp2040_gpioirq.c
@@ -0,0 +1,75 @@
+/* libhw/rp2040_gpioirq.c - Utilities for sharing the GPIO IRQ (IO_IRQ_BANK0)
+ *
+ * Copyright (C) 2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#include <hardware/structs/io_bank0.h> /* for io_bank0_hw */
+#include <hardware/irq.h> /* for irq_set_exclusive_handler() */
+
+#include <libmisc/macro.h>
+
+#include "rp2040_gpioirq.h"
+
+struct gpioirq_handler_entry {
+	gpioirq_handler_t        fn;
+	void                    *arg;
+};
+struct gpioirq_handler_entry gpioirq_handlers[NUM_BANK0_GPIOS][4] = {0};
+
+int gpioirq_core = -1;
+
+static void gpioirq_handler(void) {
+	uint core = get_core_num();
+	io_bank0_irq_ctrl_hw_t *irq_ctrl_base;
+	switch (core) {
+	case 0: irq_ctrl_base = &io_bank0_hw->proc0_irq_ctrl; break;
+	case 1: irq_ctrl_base = &io_bank0_hw->proc1_irq_ctrl; break;
+	default: assert_notreached("invalid core number");
+	}
+	for (uint regnum = 0; regnum < LM_ARRAY_LEN(irq_ctrl_base->ints); regnum++) {
+		uint32_t regval = irq_ctrl_base->ints[regnum];
+		for (uint bit = 0; bit < 32 && (regnum*8)+(bit/4) < NUM_BANK0_GPIOS; bit++) {
+			if (regval & 1u<<bit) {
+				uint gpio = (regnum*8)+(bit/4);
+				uint event_idx = bit%4;
+				struct gpioirq_handler_entry *handler = &gpioirq_handlers[gpio][event_idx];
+				if (handler->fn)
+					handler->fn(handler->arg, gpio, 1u<<event_idx);
+			}
+		}
+		/* acknowledge irq */
+		io_bank0_hw->intr[regnum] = regval;
+	}
+}
+
+void gpioirq_set_and_enable_exclusive_handler(uint gpio, enum gpio_irq_level event, gpioirq_handler_t fn, void *arg) {
+	assert(gpio < NUM_BANK0_GPIOS);
+	assert(event == GPIO_IRQ_LEVEL_LOW ||
+	       event == GPIO_IRQ_LEVEL_HIGH ||
+	       event == GPIO_IRQ_EDGE_FALL ||
+	       event == GPIO_IRQ_EDGE_RISE);
+	assert(fn);
+
+	uint event_idx = LM_FLOORLOG2(event);
+	assert(gpioirq_handlers[gpio][event_idx].fn == NULL);
+
+	uint core = get_core_num();
+	assert(gpioirq_core == -1 || gpioirq_core == (int)core);
+
+	io_bank0_irq_ctrl_hw_t *irq_ctrl_base;
+	switch (core) {
+	case 0: irq_ctrl_base = &io_bank0_hw->proc0_irq_ctrl; break;
+	case 1: irq_ctrl_base = &io_bank0_hw->proc1_irq_ctrl; break;
+	default: assert_notreached("invalid core number");
+	}
+
+	gpioirq_handlers[gpio][event_idx].fn = fn;
+	gpioirq_handlers[gpio][event_idx].arg = arg;
+	hw_set_bits(&irq_ctrl_base->inte[gpio/8], 1u<<((4*(gpio%8))+event_idx));
+	if (gpioirq_core == -1) {
+		irq_set_exclusive_handler(IO_IRQ_BANK0, gpioirq_handler);
+		irq_set_enabled(IO_IRQ_BANK0, true);
+		gpioirq_core = core;
+	}
+}
diff --git a/libhw/rp2040_gpioirq.h b/libhw/rp2040_gpioirq.h
new file mode 100644
index 0000000..06041c9
--- /dev/null
+++ b/libhw/rp2040_gpioirq.h
@@ -0,0 +1,33 @@
+/* libhw/rp2040_gpioirq.h - Utilities for sharing the GPIO IRQ (IO_IRQ_BANK0)
+ *
+ * Copyright (C) 2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIBHW_RP2040_GPIOIRQ_H_
+#define _LIBHW_RP2040_GPIOIRQ_H_
+
+#include <hardware/gpio.h> /* for enum gpio_irq_level */
+
+typedef void (*gpioirq_handler_t)(void *arg, uint gpio, enum gpio_irq_level event);
+
+/**
+ * Register `fn(arg, ...)` to be called when `event` fires on GPIO pin
+ * `gpio`.
+ *
+ * If multiple events happen close together, the handlers will not
+ * necessarily be called in-order.
+ *
+ * Your handler does not need to acknowledge the IRQ; that will be
+ * done for you after your handler is called.
+ *
+ * It is illegal to call gpioirq_set_and_enable_exclusive_handler()
+ * on multiple cores.
+ *
+ * This is better than the Pico-SDK <hardware/gpio.h> IRQ functions
+ * because their functions call the handlers for every event, and it
+ * is up to you to de-mux them in your handler.
+ */
+void gpioirq_set_and_enable_exclusive_handler(uint gpio, enum gpio_irq_level event, gpioirq_handler_t fn, void *arg);
+
+#endif /* _LIBHW_RP2040_GPIOIRQ_H_ */
diff --git a/libhw/w5500.c b/libhw/w5500.c
index 64b373b..b4ad86b 100644
--- a/libhw/w5500.c
+++ b/libhw/w5500.c
@@ -72,6 +72,7 @@
 /* TODO: Write a <libhw/generic/gpio.h> to avoid w5500.c being
  * pico-sdk-specific.  */
 #include <hardware/gpio.h> /* pico-sdk:hardware_gpio */
+#include "rp2040_gpioirq.h"
 
 #include <libcr/coroutine.h> /* for cr_yield() */
 
@@ -95,9 +96,6 @@
 #ifndef CONFIG_W5500_LOCAL_PORT_MAX
 	#error config.h must define CONFIG_W5500_LOCAL_PORT_MAX
 #endif
-#ifndef CONFIG_W5500_NUM
-	#error config.h must define CONFIG_W5500_NUM
-#endif
 #ifndef CONFIG_W5500_DEBUG
 	#error config.h must define CONFIG_W5500_DEBUG
 #endif
@@ -280,13 +278,10 @@ static inline void w5500_socket_close(struct _w5500_socket *socket) {
 
 /* init() *********************************************************************/
 
-static struct w5500 *w5500_chips[CONFIG_W5500_NUM] = {0};
-
-static void w5500_intrhandler(uint gpio, uint32_t LM_UNUSED(event_mask)) {
-	debugf("w5500_intrhandler(): interrupt on pin %u", gpio);
-	for (size_t i = 0; i < LM_ARRAY_LEN(w5500_chips); i++)
-		if (w5500_chips[i] && w5500_chips[i]->pin_intr == gpio)
-			cr_sema_signal_from_intrhandler(&w5500_chips[i]->intr);
+static void w5500_intrhandler(void *_chip, uint LM_UNUSED(gpio), enum gpio_irq_level LM_UNUSED(event)) {
+	struct w5500 *chip = _chip;
+	debugf("w5500_intrhandler()");
+	cr_sema_signal_from_intrhandler(&chip->intr);
 }
 
 void _w5500_init(struct w5500 *chip,
@@ -318,19 +313,11 @@ void _w5500_init(struct w5500 *chip,
 	}
 
 	/* Initialize the hardware.  */
-	gpio_set_irq_enabled_with_callback(pin_intr, GPIO_IRQ_EDGE_FALL, true, w5500_intrhandler);
+	gpioirq_set_and_enable_exclusive_handler(pin_intr, GPIO_IRQ_EDGE_FALL, w5500_intrhandler, chip);
 	gpio_set_dir(chip->pin_reset, GPIO_OUT);
 	w5500_hard_reset(chip);
 
 	/* Finally, wire in the interrupt handler.  */
-	bool saved = cr_save_and_disable_interrupts();
-	for (size_t i = 0; i < LM_ARRAY_LEN(w5500_chips); i++) {
-		if (w5500_chips[i] == NULL) {
-			w5500_chips[i] = chip;
-			break;
-		}
-	}
-	cr_restore_interrupts(saved);
 	coroutine_add("w5500_irq", w5500_irq_cr, chip);
 }