From c4cf1eeb2b16c471e41b2fa65e34ae06d9ec5fa9 Mon Sep 17 00:00:00 2001
From: Petro Karashchenko <petro.karashchenko@gmail.com>
Date: Wed, 25 Jan 2023 23:00:34 +0200
Subject: [PATCH] arch/xtensa/esp32s2: switch from semaphore to mutex for
 exclusive access

Signed-off-by: Petro Karashchenko <petro.karashchenko@gmail.com>
---
 arch/xtensa/src/esp32s2/esp32s2_spi.c | 47 +++++++++------------------
 1 file changed, 16 insertions(+), 31 deletions(-)

diff --git a/arch/xtensa/src/esp32s2/esp32s2_spi.c b/arch/xtensa/src/esp32s2/esp32s2_spi.c
index 990d91bf4d..36c823a9a3 100644
--- a/arch/xtensa/src/esp32s2/esp32s2_spi.c
+++ b/arch/xtensa/src/esp32s2/esp32s2_spi.c
@@ -38,7 +38,7 @@
 #include <nuttx/arch.h>
 #include <nuttx/irq.h>
 #include <nuttx/clock.h>
-#include <nuttx/semaphore.h>
+#include <nuttx/mutex.h>
 #include <nuttx/spinlock.h>
 #include <nuttx/spi/spi.h>
 
@@ -150,7 +150,7 @@ struct esp32s2_spi_priv_s
 
   const struct esp32s2_spi_config_s *config;
   int refs;             /* Reference count */
-  sem_t exclsem;        /* Held while chip is selected for mutual exclusion */
+  mutex_t lock;         /* Held while chip is selected for mutual exclusion */
 #if defined(CONFIG_ESP32S2_SPI2_DMA) || defined(CONFIG_ESP32S2_SPI3_DMA)
   sem_t sem_isr;        /* Interrupt wait semaphore */
   int cpuint;           /* SPI interrupt ID */
@@ -356,7 +356,7 @@ static struct esp32s2_spi_priv_s esp32s2_spi2_priv =
     },
   .config      = &esp32s2_spi2_config,
   .refs        = 0,
-  .exclsem     = SEM_INITIALIZER(0),
+  .lock        = NXMUTEX_INITIALIZER,
 #ifdef CONFIG_ESP32S2_SPI2_DMA
   .sem_isr     = SEM_INITIALIZER(0),
   .cpuint      = -ENOMEM,
@@ -441,7 +441,7 @@ static struct esp32s2_spi_priv_s esp32s2_spi3_priv =
     },
   .config      = &esp32s2_spi3_config,
   .refs        = 0,
-  .exclsem     = SEM_INITIALIZER(0),
+  .lock        = NXMUTEX_INITIALIZER,
 #ifdef CONFIG_ESP32S2_SPI3_DMA
   .sem_isr     = SEM_INITIALIZER(0),
   .cpuint      = -ENOMEM,
@@ -563,11 +563,11 @@ static int esp32s2_spi_lock(struct spi_dev_s *dev, bool lock)
 
   if (lock)
     {
-      ret = nxsem_wait_uninterruptible(&priv->exclsem);
+      ret = nxmutex_lock(&priv->lock);
     }
   else
     {
-      ret = nxsem_post(&priv->exclsem);
+      ret = nxmutex_unlock(&priv->lock);
     }
 
   return ret;
@@ -895,7 +895,7 @@ static int esp32s2_spi_hwfeatures(struct spi_dev_s *dev,
  *              uint16_t's
  *
  * Returned Value:
- *   None
+ *   None.
  *
  ****************************************************************************/
 
@@ -1365,10 +1365,6 @@ static void esp32s2_spi_init(struct spi_dev_s *dev)
   const uint32_t id = config->id;
   uint32_t regval;
 
-  /* Initialize the SPI semaphore that enforces mutually exclusive access */
-
-  nxsem_init(&priv->exclsem, 0, 1);
-
   esp32s2_gpiowrite(config->cs_pin, true);
   esp32s2_gpiowrite(config->mosi_pin, true);
   esp32s2_gpiowrite(config->miso_pin, true);
@@ -1519,7 +1515,6 @@ struct spi_dev_s *esp32s2_spibus_initialize(int port)
 {
   struct spi_dev_s *spi_dev;
   struct esp32s2_spi_priv_s *priv;
-  irqstate_t flags;
 
   switch (port)
     {
@@ -1539,12 +1534,11 @@ struct spi_dev_s *esp32s2_spibus_initialize(int port)
 
   spi_dev = (struct spi_dev_s *)priv;
 
-  flags = enter_critical_section();
-
+  nxmutex_lock(&priv->lock);
   if (priv->refs != 0)
     {
-      leave_critical_section(flags);
-
+      priv->refs++;
+      nxmutex_unlock(&priv->lock);
       return spi_dev;
     }
 
@@ -1571,8 +1565,7 @@ struct spi_dev_s *esp32s2_spibus_initialize(int port)
     {
       /* Failed to allocate a CPU interrupt of this type. */
 
-      leave_critical_section(flags);
-
+      nxmutex_unlock(&priv->lock);
       return NULL;
     }
 
@@ -1584,7 +1577,7 @@ struct spi_dev_s *esp32s2_spibus_initialize(int port)
 
       esp32s2_teardown_irq(priv->config->periph, priv->cpuint);
       priv->cpuint = -ENOMEM;
-      leave_critical_section(flags);
+      nxmutex_unlock(&priv->lock);
 
       return NULL;
     }
@@ -1595,11 +1588,9 @@ struct spi_dev_s *esp32s2_spibus_initialize(int port)
 #endif
 
   esp32s2_spi_init(spi_dev);
-
   priv->refs++;
 
-  leave_critical_section(flags);
-
+  nxmutex_unlock(&priv->lock);
   return spi_dev;
 }
 
@@ -1619,7 +1610,6 @@ struct spi_dev_s *esp32s2_spibus_initialize(int port)
 
 int esp32s2_spibus_uninitialize(struct spi_dev_s *dev)
 {
-  irqstate_t flags;
   struct esp32s2_spi_priv_s *priv = (struct esp32s2_spi_priv_s *)dev;
 
   DEBUGASSERT(dev);
@@ -1629,16 +1619,13 @@ int esp32s2_spibus_uninitialize(struct spi_dev_s *dev)
       return ERROR;
     }
 
-  flags = enter_critical_section();
-
+  nxmutex_lock(&priv->lock);
   if (--priv->refs != 0)
     {
-      leave_critical_section(flags);
+      nxmutex_unlock(&priv->lock);
       return OK;
     }
 
-  leave_critical_section(flags);
-
 #if defined(CONFIG_ESP32S2_SPI2_DMA) || defined(CONFIG_ESP32S2_SPI3_DMA)
   up_disable_irq(priv->config->irq);
   esp32s2_teardown_irq(priv->config->periph, priv->cpuint);
@@ -1646,12 +1633,10 @@ int esp32s2_spibus_uninitialize(struct spi_dev_s *dev)
 
   priv->cpuint = -ENOMEM;
 
-  nxsem_destroy(&priv->sem_isr);
 #endif
 
   esp32s2_spi_deinit(dev);
-
-  nxsem_destroy(&priv->exclsem);
+  nxmutex_unlock(&priv->lock);
 
   return OK;
 }