drivers/spi: Add reentrance support to DW driver in a generic manner

Let's improve common SPI driver context by adding a lock and generic
function to get/release it.

It's statically initialized to save a bit of ROM.

Signed-off-by: Tomasz Bursztyka <[email protected]>

Author: Tomasz Bursztyka

drivers/spi/spi_context.h

@@ -22,6 +22,8 @@ extern "C" {
 struct spi_context {
 	struct spi_config *config;
 
+	struct k_sem lock;
+
 	const struct spi_buf **current_tx;
 	struct spi_buf **current_rx;
 
@@ -31,12 +33,25 @@ struct spi_context {
 	u32_t rx_len;
 };
 
+#define SPI_CONTEXT_INIT_LOCK(_data, _ctx_name)				\
+	._ctx_name.lock = K_SEM_INITIALIZER(_data._ctx_name.lock, 0, 1)
+
 static inline bool spi_context_configured(struct spi_context *ctx,
 					  struct spi_config *config)
 {
 	return !!(ctx->config == config);
 }
 
+static inline void spi_context_lock(struct spi_context *ctx)
+{
+	k_sem_take(&ctx->lock, K_FOREVER);
+}
+
+static inline void spi_context_release(struct spi_context *ctx)
+{
+	k_sem_give(&ctx->lock);
+}
+
 static inline void spi_context_cs_configure(struct spi_context *ctx)
 {
 	if (ctx->config->cs) {

drivers/spi/spi_dw.c

@@ -259,6 +259,7 @@ static int spi_dw_transceive(struct device *dev,
 	struct spi_dw_data *spi = dev->driver_data;
 	u32_t rx_thsld = DW_SPI_RXFTLR_DFLT;
 	u32_t imask = DW_SPI_IMR_UNMASK;
+	int ret = 0;
 
 	SYS_LOG_DBG("%p, %p, %p", dev, tx_bufs, rx_bufs);
 
@@ -268,9 +269,12 @@ static int spi_dw_transceive(struct device *dev,
 		return -EBUSY;
 	}
 
+	spi_context_lock(&spi->ctx);
+
 	/* Configure */
-	if (spi_dw_configure(info, spi, config)) {
-		return -EINVAL;
+	ret = spi_dw_configure(info, spi, config);
+	if (ret) {
+		goto out;
 	}
 
 	/* Set buffers info */
@@ -305,11 +309,12 @@ static int spi_dw_transceive(struct device *dev,
 	k_sem_take(&spi->device_sync_sem, K_FOREVER);
 
 	if (spi->error) {
-		spi->error = 0;
-		return -EIO;
+		ret = -EIO;
 	}
+out:
+	spi_context_release(&spi->ctx);
 
-	return 0;
+	return ret;
 }
 
 void spi_dw_isr(struct device *dev)
@@ -365,14 +370,18 @@ int spi_dw_init(struct device *dev)
 
 	SYS_LOG_DBG("Designware SPI driver initialized on device: %p", dev);
 
+	spi_context_release(&spi->ctx);
+
 	return 0;
 }
 
 
 #ifdef CONFIG_SPI_0
 void spi_config_0_irq(void);
 
-struct spi_dw_data spi_dw_data_port_0;
+struct spi_dw_data spi_dw_data_port_0 = {
+	SPI_CONTEXT_INIT_LOCK(spi_dw_data_port_0, ctx),
+};
 
 const struct spi_dw_config spi_dw_config_0 = {
 	.regs = SPI_DW_PORT_0_REGS,
@@ -415,7 +424,9 @@ void spi_config_0_irq(void)
 #ifdef CONFIG_SPI_1
 void spi_config_1_irq(void);
 
-struct spi_dw_data spi_dw_data_port_1;
+struct spi_dw_data spi_dw_data_port_1 = {
+	SPI_CONTEXT_INIT_LOCK(spi_dw_data_port_1, ctx),
+};
 
 static const struct spi_dw_config spi_dw_config_1 = {
 	.regs = SPI_DW_PORT_1_REGS,