spi: dw: Add generic DW SSI status-check method

The DW SSI errors handling method can be generically implemented for all
types of the transfers: IRQ, DMA and poll-based ones. It will be a
function which checks the overflow/underflow error flags and resets the
controller if any of them is set. In the framework of this commit we make
use of the new method to detect the errors in the IRQ- and DMA-based SPI
transfer execution procedures.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201007235511.4935-17-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-dw-core.c

@@ -169,23 +169,48 @@ static void dw_reader(struct dw_spi *dws)
 	}
 }
 
-static void int_error_stop(struct dw_spi *dws, const char *msg)
+int dw_spi_check_status(struct dw_spi *dws, bool raw)
 {
-	spi_reset_chip(dws);
+	u32 irq_status;
+	int ret = 0;
+
+	if (raw)
+		irq_status = dw_readl(dws, DW_SPI_RISR);
+	else
+		irq_status = dw_readl(dws, DW_SPI_ISR);
+
+	if (irq_status & SPI_INT_RXOI) {
+		dev_err(&dws->master->dev, "RX FIFO overflow detected\n");
+		ret = -EIO;
+	}
+
+	if (irq_status & SPI_INT_RXUI) {
+		dev_err(&dws->master->dev, "RX FIFO underflow detected\n");
+		ret = -EIO;
+	}
 
-	dev_err(&dws->master->dev, "%s\n", msg);
-	dws->master->cur_msg->status = -EIO;
-	spi_finalize_current_transfer(dws->master);
+	if (irq_status & SPI_INT_TXOI) {
+		dev_err(&dws->master->dev, "TX FIFO overflow detected\n");
+		ret = -EIO;
+	}
+
+	/* Generically handle the erroneous situation */
+	if (ret) {
+		spi_reset_chip(dws);
+		if (dws->master->cur_msg)
+			dws->master->cur_msg->status = ret;
+	}
+
+	return ret;
 }
+EXPORT_SYMBOL_GPL(dw_spi_check_status);
 
 static irqreturn_t dw_spi_transfer_handler(struct dw_spi *dws)
 {
 	u16 irq_status = dw_readl(dws, DW_SPI_ISR);
 
-	/* Error handling */
-	if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
-		dw_readl(dws, DW_SPI_ICR);
-		int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
+	if (dw_spi_check_status(dws, false)) {
+		spi_finalize_current_transfer(dws->master);
 		return IRQ_HANDLED;
 	}
 

drivers/spi/spi-dw-dma.c

@@ -176,17 +176,10 @@ static void dw_spi_dma_exit(struct dw_spi *dws)
 
 static irqreturn_t dw_spi_dma_transfer_handler(struct dw_spi *dws)
 {
-	u16 irq_status = dw_readl(dws, DW_SPI_ISR);
+	dw_spi_check_status(dws, false);
 
-	if (!irq_status)
-		return IRQ_NONE;
-
-	dw_readl(dws, DW_SPI_ICR);
-	spi_reset_chip(dws);
-
-	dev_err(&dws->master->dev, "%s: FIFO overrun/underrun\n", __func__);
-	dws->master->cur_msg->status = -EIO;
 	complete(&dws->dma_completion);
+
 	return IRQ_HANDLED;
 }
 

drivers/spi/spi-dw.h

@@ -262,6 +262,7 @@ static inline void spi_shutdown_chip(struct dw_spi *dws)
 extern void dw_spi_set_cs(struct spi_device *spi, bool enable);
 extern void dw_spi_update_config(struct dw_spi *dws, struct spi_device *spi,
 				 struct dw_spi_cfg *cfg);
+extern int dw_spi_check_status(struct dw_spi *dws, bool raw);
 extern int dw_spi_add_host(struct device *dev, struct dw_spi *dws);
 extern void dw_spi_remove_host(struct dw_spi *dws);
 extern int dw_spi_suspend_host(struct dw_spi *dws);