SPI CS fix from Zephyr patch

fw/src/app/spi.c

@@ -12,63 +12,77 @@ static pi_to_hat_t  pi_to_hat;
 static hat_to_pi_t  hat_to_pi;
 
 typedef struct fifo_item_t {
-	void *fifo_reserved; /* 1st word reserved for use by fifo */
-	pi_to_hat_t msg;
+    void *fifo_reserved; /* 1st word reserved for use by fifo */
+    pi_to_hat_t msg;
 } fifo_item_t;
 
 fifo_item_t fifo_rx_queue;
 
 K_FIFO_DEFINE(my_fifo);
 
+// Read message received from the pi out of the FIFO
+// Call not thread safe. Run from one thread at a time.
+// Returned message buffer must be freed after processing is done.
 int wait_for_pi_message(pi_to_hat_t* msg, int32_t timeout)
 {
     fifo_item_t *rx_data = k_fifo_get(&my_fifo, timeout);
-	if (rx_data == NULL)
-		return -1;
+    if (rx_data == NULL)
+        return -1;
 
     // shallow copy ok?
-	*msg = rx_data->msg;
+    *msg = rx_data->msg;
     k_free(rx_data);
-	return 0;
+    return 0;
 }
 
-void spi_task(void)
+// Zephyr thread to read and write data over the
+// SPI bus to/from the pi.
+void spi_task(void) 
 {
-	struct device *spi;
-	struct spi_config       spi_cfg;
-	struct spi_cs_control   spi_cs;
-
-	spi = device_get_binding("SPI_1");
-	if (!spi)
-	{
-		LOG_ERR("Could not find SPI driver\n");
-		return;
-	}
-
-	spi_cfg.operation = SPI_WORD_SET(8) | SPI_OP_MODE_SLAVE;
-	spi_cfg.frequency = 25000000;
-
-	spi_cs.gpio_dev = device_get_binding(DT_INST_0_ST_STM32_SPI_CS_GPIOS_CONTROLLER);
-	spi_cs.gpio_pin = DT_INST_0_ST_STM32_SPI_CS_GPIOS_PIN;
-	spi_cs.delay = 0;
-	spi_cfg.cs = &spi_cs;
-
-	LOG_INF("SPI interface listening");
-
-	const struct spi_buf tx_buf = {
-		.buf = &hat_to_pi,
-		.len = sizeof(hat_to_pi)
-	};
-	const struct spi_buf rx_buf =
-	{
-		.buf = &pi_to_hat,
-		.len = sizeof(pi_to_hat)
-	};
-	const struct spi_buf_set tx = { .buffers = &tx_buf, .count = 1 };
-	const struct spi_buf_set rx = { .buffers = &rx_buf, .count = 1 };
-
-	while(true)
-	{
+    struct device *spi;
+    struct spi_config       spi_cfg;
+    struct spi_cs_control   spi_cs;
+    int spi_trancieve_ret = 0;
+
+    // Get SPI device binding from Zephyr device tree
+    spi = device_get_binding("SPI_1");
+    if (!spi)
+    {
+    	LOG_ERR("Could not find SPI driver\n");
+    	return;
+    }
+
+    // Set-up config struct for SPI
+    // Note: using custom patch for Zephyr 2.1 SPI driver to correct operation
+    // in slave mode. OS upgrades will need the patch implemented in spi_ll_stm32.c
+    // and spi_context.h. spi_cfg.cs must be set for patch to work correctly.
+    spi_cfg.operation = SPI_WORD_SET(8) | SPI_OP_MODE_SLAVE;
+    spi_cfg.frequency = 25000000;
+
+    spi_cs.gpio_dev = device_get_binding(DT_INST_0_ST_STM32_SPI_CS_GPIOS_CONTROLLER);
+    spi_cs.gpio_pin = DT_INST_0_ST_STM32_SPI_CS_GPIOS_PIN;
+    spi_cs.delay = 0;
+    spi_cfg.cs = &spi_cs;
+
+    LOG_INF("SPI interface listening");
+
+    // Init Rx and Tx buffers
+    const struct spi_buf tx_buf = {
+        .buf = &hat_to_pi,
+        .len = sizeof(hat_to_pi)
+    };
+    const struct spi_buf rx_buf =
+    {
+        .buf = &pi_to_hat,
+        .len = sizeof(pi_to_hat)
+    };
+    const struct spi_buf_set tx = { .buffers = &tx_buf, .count = 1 };
+    const struct spi_buf_set rx = { .buffers = &rx_buf, .count = 1 };
+
+    // Infinite loop in dedicated thread to transfer data over SPI bus
+    while(true)
+    {
+        // Fill Tx buff with message for PI
         memset(&pi_to_hat, 0, sizeof(pi_to_hat));       // 8 bytes from Raspberry Pi (Tx)
         memset(&hat_to_pi, 0, sizeof(hat_to_pi));       // 8 bytes to   Raspberry Pi (Rx)
 
@@ -80,18 +94,33 @@ void spi_task(void)
         // tx: outbound (button state and joystick positions)
         // rx: incoming (command verbs)
 
-		if (spi_transceive(spi, &spi_cfg, &tx, &rx) > 0)
-		{
+        // Send and recieve data from the Pi. No limit on wait length.
+        spi_trancieve_ret = spi_transceive(spi, &spi_cfg, &tx, &rx);
+
+        // Process transfer results
+        if(spi_trancieve_ret != sizeof(pi_to_hat))
+        {
+            // did not recieve full length packet or an error was encountered
+            // in the SPI driver during the transfer
+
+            if(spi_trancieve_ret >= 0) // was the data the wrong length?
+                LOG_INF("Recieved %d bytes from pi but expected %d.", spi_trancieve_ret, sizeof(pi_to_hat));
+            else // Internal SPI driver error
+                LOG_ERR("Pi-Hat spi_transceive() returned with error: %d", spi_trancieve_ret);
+        }
+        else
+        {
+            // Valid packet was recieved. Put on FIFO queue for later processing.
             size_t size = sizeof(fifo_item_t);
             fifo_item_t *ptr = (fifo_item_t *) k_malloc(size);
             __ASSERT_NO_MSG(ptr != 0);
 
             ptr->fifo_reserved = 0x0;           // don't care
             memcpy(&ptr->msg, &pi_to_hat, sizeof(pi_to_hat));
 
-			k_fifo_put(&my_fifo, ptr);
-		}
-	}
+            k_fifo_put(&my_fifo, ptr);
+        }
+    }
 }
 
 K_THREAD_DEFINE(spi_task_id, STACKSIZE, spi_task, NULL, NULL, NULL, PRIORITY, 0, K_NO_WAIT);

fw/src/doit

@@ -78,6 +78,7 @@ install() {
 
         echo "Installing $DEST/$FN on moab"
         scp "$DEST/$FN" moab:$FN || echo "scp copy to moab failed"
+		sleep 5
         ssh moab "sudo moab/bin/flash /home/pi/$FN"
     fi 
 }

fw/src/prj.conf

@@ -63,7 +63,7 @@ CONFIG_SPI_INIT_PRIORITY=70
 CONFIG_SPI_0=y
 CONFIG_SPI_0_OP_MODES=1
 CONFIG_SPI_1=y
-CONFIG_SPI_1_OP_MODES=1
+CONFIG_SPI_1_OP_MODES=2
 CONFIG_SPI_2=y
 CONFIG_SPI_2_OP_MODES=1
 CONFIG_SPI_STM32_INTERRUPT=y