From 5129d249e9893b3bcae58b2e655b3e5693e1b760 Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Fri, 19 Aug 2022 15:18:41 +0200
Subject: [PATCH] cpu/nrf52: add locking for shared peripherals

---
 cpu/nrf52/include/periph_cpu.h | 28 ++++++++++++++++++++++++++++
 cpu/nrf52/spi_twi_irq.c        | 27 +++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/cpu/nrf52/include/periph_cpu.h b/cpu/nrf52/include/periph_cpu.h
index 7f3bef6051..d888c0a55c 100644
--- a/cpu/nrf52/include/periph_cpu.h
+++ b/cpu/nrf52/include/periph_cpu.h
@@ -264,6 +264,34 @@ void spi_twi_irq_register_spi(NRF_SPIM_Type *bus,
 void spi_twi_irq_register_i2c(NRF_TWIM_Type *bus,
                               spi_twi_irq_cb_t cb, void *arg);
 
+/**
+ * @brief   Acquire the shared I2C/SPI peripheral in I2C mode
+ *
+ * @param   bus bus to acquire exclusive access on
+ */
+void nrf5x_i2c_acquire(NRF_TWIM_Type *bus);
+
+/**
+ * @brief   Release the shared I2C/SPI peripheral in I2C mode
+ *
+ * @param   bus bus to release exclusive access on
+ */
+void nrf5x_i2c_release(NRF_TWIM_Type *bus);
+
+/**
+ * @brief   Acquire the shared I2C/SPI peripheral in SPI mode
+ *
+ * @param   bus bus to acquire exclusive access on
+ */
+void nrf5x_spi_release(NRF_SPIM_Type *bus);
+
+/**
+ * @brief   Acquire the shared I2C/SPI peripheral in SPI mode
+ *
+ * @param   bus bus to release exclusive access on
+ */
+void nrf5x_spi_acquire(NRF_SPIM_Type *bus);
+
 /**
  * @brief USBDEV buffers must be word aligned because of DMA restrictions
  */
diff --git a/cpu/nrf52/spi_twi_irq.c b/cpu/nrf52/spi_twi_irq.c
index 73fa24751d..6db7b0065f 100644
--- a/cpu/nrf52/spi_twi_irq.c
+++ b/cpu/nrf52/spi_twi_irq.c
@@ -24,6 +24,7 @@
 #include <assert.h>
 
 #include "cpu.h"
+#include "mutex.h"
 #include "periph_cpu.h"
 
 #if NRF_SPIM0_BASE != NRF_TWIM0_BASE
@@ -59,6 +60,8 @@
 static spi_twi_irq_cb_t _irq[SPIM_COUNT];
 static void *_irq_arg[SPIM_COUNT];
 
+static mutex_t _locks[SPIM_COUNT];
+
 /* I2C and SPI share peripheral addresses */
 static size_t _spi_dev2num(void *dev)
 {
@@ -140,6 +143,30 @@ void spi_twi_irq_register_i2c(NRF_TWIM_Type *bus,
     NVIC_EnableIRQ(_isr[num]);
 }
 
+void nrf5x_i2c_acquire(NRF_TWIM_Type *bus)
+{
+    size_t num = _i2c_dev2num(bus);
+    mutex_lock(&_locks[num]);
+}
+
+void nrf5x_spi_acquire(NRF_SPIM_Type *bus)
+{
+    size_t num = _spi_dev2num(bus);
+    mutex_lock(&_locks[num]);
+}
+
+void nrf5x_i2c_release(NRF_TWIM_Type *bus)
+{
+    size_t num = _i2c_dev2num(bus);
+    mutex_unlock(&_locks[num]);
+}
+
+void nrf5x_spi_release(NRF_SPIM_Type *bus)
+{
+    size_t num = _spi_dev2num(bus);
+    mutex_unlock(&_locks[num]);
+}
+
 void ISR_SPIM0(void)
 {
     _irq[0](_irq_arg[0]);