nfc: Introduce Zero Latency IRQ

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -719,6 +719,7 @@ Libraries for NFC
 -----------------
 
 * Fixed an issue with handling zero size data (when receiving empty I-blocks from poller) in the :file:`platform_internal_thread` file.
+* Added support for zero-latency interrupts for all NFC libraries.
 
 nRF Security
 ------------

subsys/nfc/lib/CMakeLists.txt

@@ -6,6 +6,7 @@
 zephyr_library()
 if(CONFIG_NFC_PLATFORM)
   zephyr_library_sources(platform.c)
+  zephyr_library_sources(platform_internal_hfclk.c)
   zephyr_library_sources_ifdef(CONFIG_NFC_THREAD_CALLBACK platform_internal_thread.c)
   zephyr_library_sources_ifndef(CONFIG_NFC_THREAD_CALLBACK platform_internal_irq.c)
 endif()

subsys/nfc/lib/Kconfig

@@ -81,14 +81,16 @@ config NFC_THREAD_PRIORITY
 
 endif# NFC_OWN_THREAD
 
-config NFC_LOW_LATENCY_IRQ
-	bool "Use low latency IRQ for NFC"
-	default y
+config NFC_ZERO_LATENCY_IRQ
+	bool "Use zero latency IRQ for NFC"
+	default n
+	select ZERO_LATENCY_IRQS
+	select EXPERIMENTAL
 	help
-	  Using this option ensures fast NFC interrupt
+	  Using this option ensures zero latency NFC interrupt
 	  execution on the cost of using additional interrupt (SWI).
 
-if NFC_LOW_LATENCY_IRQ
+if NFC_ZERO_LATENCY_IRQ
 
 config NFC_SWI_NUMBER
 	int

subsys/nfc/lib/platform.c

@@ -4,8 +4,6 @@
  * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
  */
 #include <zephyr/kernel.h>
-#include <zephyr/drivers/clock_control.h>
-#include <zephyr/drivers/clock_control/nrf_clock_control.h>
 #include <nrfx_nfct.h>
 #include <nrfx_timer.h>
 #include <nfc_platform.h>
@@ -28,8 +26,11 @@ LOG_MODULE_REGISTER(nfc_platform, CONFIG_NFC_PLATFORM_LOG_LEVEL);
 
 #define DT_DRV_COMPAT nordic_nrf_clock
 
-static struct onoff_manager *hf_mgr;
-static struct onoff_client cli;
+#ifdef CONFIG_NFC_ZERO_LATENCY_IRQ
+#define NFCT_IRQ_FLAGS IRQ_ZERO_LATENCY
+#else
+#define NFCT_IRQ_FLAGS 0
+#endif /* CONFIG_NFC_ZERO_LATENCY_IRQ */
 
 ISR_DIRECT_DECLARE(nfc_isr_wrapper)
 {
@@ -43,21 +44,16 @@ ISR_DIRECT_DECLARE(nfc_isr_wrapper)
 	return 1;
 }
 
-static void clock_handler(struct onoff_manager *mgr, int res)
-{
-	/* Activate NFCT only when HFXO is running */
-	nrfx_nfct_state_force(NRFX_NFCT_STATE_ACTIVATED);
-}
-
 nrfx_err_t nfc_platform_setup(nfc_lib_cb_resolve_t nfc_lib_cb_resolve)
 {
 	int err;
 
-	hf_mgr = z_nrf_clock_control_get_onoff(CLOCK_CONTROL_NRF_SUBSYS_HF);
-	__ASSERT_NO_MSG(hf_mgr);
+	err = nfc_platform_internal_hfclk_init();
+	__ASSERT_NO_MSG(err == 0);
 
 	IRQ_DIRECT_CONNECT(NFCT_IRQn, CONFIG_NFCT_IRQ_PRIORITY,
-			   nfc_isr_wrapper, 0);
+			   nfc_isr_wrapper, NFCT_IRQ_FLAGS);
+
 	IRQ_CONNECT(NFC_TIMER_IRQn, CONFIG_NFCT_IRQ_PRIORITY,
 		    nfc_timer_irq_handler, NULL,  0);
 
@@ -156,32 +152,3 @@ nrfx_err_t nfc_platform_nfcid1_default_bytes_get(uint8_t * const buf,
 
 	return NRFX_SUCCESS;
 }
-
-
-void nfc_platform_event_handler(nrfx_nfct_evt_t const *event)
-{
-	int err;
-
-	switch (event->evt_id) {
-	case NRFX_NFCT_EVT_FIELD_DETECTED:
-		LOG_DBG("Field detected");
-
-		sys_notify_init_callback(&cli.notify, clock_handler);
-		err = onoff_request(hf_mgr, &cli);
-		__ASSERT_NO_MSG(err >= 0);
-
-		break;
-
-	case NRFX_NFCT_EVT_FIELD_LOST:
-		LOG_DBG("Field lost");
-
-		err = onoff_cancel_or_release(hf_mgr, &cli);
-		__ASSERT_NO_MSG(err >= 0);
-
-		break;
-
-	default:
-		/* No implementation required */
-		break;
-	}
-}

subsys/nfc/lib/platform_internal.h

@@ -33,6 +33,33 @@ extern "C" {
  */
 int nfc_platform_internal_init(nfc_lib_cb_resolve_t cb_rslv);
 
+/** @brief Initialize internal hfclk (high frequency clock) control.
+ *
+ *  This function should not be used directly.
+ *
+ *  @retval 0 If the operation was successful.
+ *  @retval -EIO Initialization failed.
+ */
+int nfc_platform_internal_hfclk_init(void);
+
+/** @brief Start hfclk.
+ *
+ *  This function should not be used directly.
+ *
+ *  @retval 0 If the operation was successful.
+ *            Otherwise, a (negative) error code is returned.
+ */
+int nfc_platform_internal_hfclk_start(void);
+
+/** @brief Stop hfclk.
+ *
+ *  This function should not be used directly.
+ *
+ *  @retval 0 If the operation was successful.
+ *            Otherwise, a (negative) error code is returned.
+ */
+int nfc_platform_internal_hfclk_stop(void);
+
 #ifdef __cplusplus
 }
 #endif

subsys/nfc/lib/platform_internal_hfclk.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2023 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+#include <zephyr/kernel.h>
+#include <nrfx_nfct.h>
+#include <zephyr/drivers/clock_control.h>
+#include <zephyr/drivers/clock_control/nrf_clock_control.h>
+#include "platform_internal.h"
+
+static struct onoff_manager *hf_mgr;
+static struct onoff_client cli;
+
+static void clock_handler(struct onoff_manager *mgr, int res)
+{
+	/* Activate NFCT only when HFXO is running */
+	nrfx_nfct_state_force(NRFX_NFCT_STATE_ACTIVATED);
+}
+
+int nfc_platform_internal_hfclk_init(void)
+{
+	hf_mgr = z_nrf_clock_control_get_onoff(CLOCK_CONTROL_NRF_SUBSYS_HF);
+
+	if (hf_mgr) {
+		return 0;
+	} else {
+		return -EIO;
+	}
+}
+
+int nfc_platform_internal_hfclk_start(void)
+{
+	sys_notify_init_callback(&cli.notify, clock_handler);
+	return onoff_request(hf_mgr, &cli);
+}
+
+int nfc_platform_internal_hfclk_stop(void)
+{
+	return onoff_cancel_or_release(hf_mgr, &cli);
+}

subsys/nfc/lib/platform_internal_irq.c

@@ -7,6 +7,10 @@
 #include <nfc_platform.h>
 #include "platform_internal.h"
 
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_DECLARE(nfc_platform, CONFIG_NFC_PLATFORM_LOG_LEVEL);
+
 static nfc_lib_cb_resolve_t nfc_cb_resolve;
 
 int nfc_platform_internal_init(nfc_lib_cb_resolve_t cb_rslv)
@@ -28,3 +32,30 @@ void nfc_platform_cb_request(const void *ctx,
 	__ASSERT(nfc_cb_resolve != NULL, "nfc_cb_resolve is not set");
 	nfc_cb_resolve(ctx, data);
 }
+
+void nfc_platform_event_handler(nrfx_nfct_evt_t const *event)
+{
+	int err;
+
+	switch (event->evt_id) {
+	case NRFX_NFCT_EVT_FIELD_DETECTED:
+		LOG_DBG("Field detected");
+
+		err = nfc_platform_internal_hfclk_start();
+		__ASSERT_NO_MSG(err >= 0);
+
+		break;
+
+	case NRFX_NFCT_EVT_FIELD_LOST:
+		LOG_DBG("Field lost");
+
+		err = nfc_platform_internal_hfclk_stop();
+		__ASSERT_NO_MSG(err >= 0);
+
+		break;
+
+	default:
+		/* No implementation required */
+		break;
+	}
+}