linux-kernel - [PATCH 6/6] spi: stm32: finalize message either on dma callback or EOT

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Message-ID: <1625042723-661-7-git-send-email-alain.volmat@foss.st.com>
Date:   Wed, 30 Jun 2021 10:45:23 +0200
From:   Alain Volmat <alain.volmat@...s.st.com>
To:     <broonie@...nel.org>, <amelie.delaunay@...s.st.com>
CC:     <mcoquelin.stm32@...il.com>, <alexandre.torgue@...s.st.com>,
        <linux-spi@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <fabrice.gasnier@...s.st.com>,
        <alain.volmat@...s.st.com>
Subject: [PATCH 6/6] spi: stm32: finalize message either on dma callback or EOT

Depending on the usage, it is necessary to perform the finalize
message operation either upon receiving the EOT interruption,
eiher upon receiving the DMA callback. Indeed, when relying
on DMA, even if the SPI EOT IT has been received, it is
necessary to wait for the end of the DMA RX transaction before
accessing to the data.

Signed-off-by: Alain Volmat <alain.volmat@...s.st.com>
---
 drivers/spi/spi-stm32.c | 57 +++++++++++++++--------------------------
 1 file changed, 20 insertions(+), 37 deletions(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 535f4bebc010..14ca7ea04e47 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -911,7 +911,10 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 	if (sr & STM32H7_SPI_SR_EOT) {
 		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
 			stm32h7_spi_read_rxfifo(spi);
-		end = true;
+		if (!spi->cur_usedma ||
+		    (spi->cur_usedma && (spi->cur_comm == SPI_SIMPLEX_TX ||
+		     spi->cur_comm == SPI_3WIRE_TX)))
+			end = true;
 	}
 
 	if (sr & STM32H7_SPI_SR_TXP)
@@ -1019,42 +1022,17 @@ static void stm32f4_spi_dma_tx_cb(void *data)
 }
 
 /**
- * stm32f4_spi_dma_rx_cb - dma callback
+ * stm32_spi_dma_rx_cb - dma callback
  * @data: pointer to the spi controller data structure
  *
  * DMA callback is called when the transfer is complete for DMA RX channel.
  */
-static void stm32f4_spi_dma_rx_cb(void *data)
+static void stm32_spi_dma_rx_cb(void *data)
 {
 	struct stm32_spi *spi = data;
 
 	spi_finalize_current_transfer(spi->master);
-	stm32f4_spi_disable(spi);
-}
-
-/**
- * stm32h7_spi_dma_cb - dma callback
- * @data: pointer to the spi controller data structure
- *
- * DMA callback is called when the transfer is complete or when an error
- * occurs. If the transfer is complete, EOT flag is raised.
- */
-static void stm32h7_spi_dma_cb(void *data)
-{
-	struct stm32_spi *spi = data;
-	unsigned long flags;
-	u32 sr;
-
-	spin_lock_irqsave(&spi->lock, flags);
-
-	sr = readl_relaxed(spi->base + STM32H7_SPI_SR);
-
-	spin_unlock_irqrestore(&spi->lock, flags);
-
-	if (!(sr & STM32H7_SPI_SR_EOT))
-		dev_warn(spi->dev, "DMA error (sr=0x%08x)\n", sr);
-
-	/* Now wait for EOT, or SUSP or OVR in case of error */
+	spi->cfg->disable(spi);
 }
 
 /**
@@ -1220,11 +1198,13 @@ static void stm32f4_spi_transfer_one_dma_start(struct stm32_spi *spi)
  */
 static void stm32h7_spi_transfer_one_dma_start(struct stm32_spi *spi)
 {
-	/* Enable the interrupts relative to the end of transfer */
-	stm32_spi_set_bits(spi, STM32H7_SPI_IER, STM32H7_SPI_IER_EOTIE |
-						 STM32H7_SPI_IER_TXTFIE |
-						 STM32H7_SPI_IER_OVRIE |
-						 STM32H7_SPI_IER_MODFIE);
+	uint32_t ier = STM32H7_SPI_IER_OVRIE | STM32H7_SPI_IER_MODFIE;
+
+	/* Enable the interrupts */
+	if (spi->cur_comm == SPI_SIMPLEX_TX || spi->cur_comm == SPI_3WIRE_TX)
+		ier |= STM32H7_SPI_IER_EOTIE | STM32H7_SPI_IER_TXTFIE;
+
+	stm32_spi_set_bits(spi, STM32H7_SPI_IER, ier);
 
 	stm32_spi_enable(spi);
 
@@ -1736,7 +1716,7 @@ static const struct stm32_spi_cfg stm32f4_spi_cfg = {
 	.set_mode = stm32f4_spi_set_mode,
 	.transfer_one_dma_start = stm32f4_spi_transfer_one_dma_start,
 	.dma_tx_cb = stm32f4_spi_dma_tx_cb,
-	.dma_rx_cb = stm32f4_spi_dma_rx_cb,
+	.dma_rx_cb = stm32_spi_dma_rx_cb,
 	.transfer_one_irq = stm32f4_spi_transfer_one_irq,
 	.irq_handler_event = stm32f4_spi_irq_event,
 	.irq_handler_thread = stm32f4_spi_irq_thread,
@@ -1756,8 +1736,11 @@ static const struct stm32_spi_cfg stm32h7_spi_cfg = {
 	.set_data_idleness = stm32h7_spi_data_idleness,
 	.set_number_of_data = stm32h7_spi_number_of_data,
 	.transfer_one_dma_start = stm32h7_spi_transfer_one_dma_start,
-	.dma_rx_cb = stm32h7_spi_dma_cb,
-	.dma_tx_cb = stm32h7_spi_dma_cb,
+	.dma_rx_cb = stm32_spi_dma_rx_cb,
+	/*
+	 * dma_tx_cb is not necessary since in case of TX, dma is followed by
+	 * SPI access hence handling is performed within the SPI interrupt
+	 */
 	.transfer_one_irq = stm32h7_spi_transfer_one_irq,
 	.irq_handler_thread = stm32h7_spi_irq_thread,
 	.baud_rate_div_min = STM32H7_SPI_MBR_DIV_MIN,
-- 
2.25.1