linux-kernel - [PATCH 06/18] spi: stm32h7: fix irq handler

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Date:   Wed, 5 Aug 2020 09:02:01 +0200
From:   Alain Volmat <alain.volmat@...com>
To:     <broonie@...nel.org>, <amelie.delaunay@...com>
CC:     <mcoquelin.stm32@...il.com>, <alexandre.torgue@...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@...com>,
        <alain.volmat@...com>
Subject: [PATCH 06/18] spi: stm32h7: fix irq handler

From: Amelie Delaunay <amelie.delaunay@...com>

Check the expected flags in irq handler instead of all flags set in
status register and clear only flags that are not automatically cleared
by hardware.
In case of Full-Duplex mode, DXP flag is set when RXP and TXP flags are
set. But to avoid 2 different handlings, just add TXP and RXP flag in
the mask instead of DXP, and then keep the initial handling of TXP and
RXP events.
Also rephrase comment about EOTIE which is one of the interrupt enable
bits. It is not triggered by any event.

Signed-off-by: Amelie Delaunay <amelie.delaunay@...com>
Signed-off-by: Antonio Borneo <antonio.borneo@...com>
Signed-off-by: Alain Volmat <alain.volmat@...com>
---
 drivers/spi/spi-stm32.c | 40 ++++++++++++++++++++++++++--------------
 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index b90367d522f2..bbda73937668 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -131,6 +131,7 @@
 #define STM32H7_SPI_SR_RXP		BIT(0)
 #define STM32H7_SPI_SR_TXP		BIT(1)
 #define STM32H7_SPI_SR_EOT		BIT(3)
+#define STM32H7_SPI_SR_TXTF		BIT(4)
 #define STM32H7_SPI_SR_OVR		BIT(6)
 #define STM32H7_SPI_SR_SUSP		BIT(11)
 #define STM32H7_SPI_SR_RXPLVL		GENMASK(14, 13)
@@ -881,7 +882,7 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 {
 	struct spi_master *master = dev_id;
 	struct stm32_spi *spi = spi_master_get_devdata(master);
-	u32 sr, ier, mask;
+	u32 sr, ier, mask, ifcr;
 	unsigned long flags;
 	bool end = false;
 
@@ -889,26 +890,31 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 
 	sr = readl_relaxed(spi->base + STM32H7_SPI_SR);
 	ier = readl_relaxed(spi->base + STM32H7_SPI_IER);
+	ifcr = 0;
 
 	mask = ier;
-	/* EOTIE is triggered on EOT, SUSP and TXC events. */
+	/*
+	 * EOTIE enables irq from EOT, SUSP and TXC events. We need to set
+	 * SUSP to acknowledge it later. TXC is automatically cleared
+	 */
 	mask |= STM32H7_SPI_SR_SUSP;
 	/*
-	 * When TXTF is set, DXPIE and TXPIE are cleared. So in case of
-	 * Full-Duplex, need to poll RXP event to know if there are remaining
-	 * data, before disabling SPI.
+	 * DXPIE is set in Full-Duplex, one IT will be raised if TXP and RXP
+	 * are set. So in case of Full-Duplex, need to poll TXP and RXP event.
 	 */
-	if (spi->rx_buf && !spi->cur_usedma)
-		mask |= STM32H7_SPI_SR_RXP;
+	if ((spi->cur_comm == SPI_FULL_DUPLEX) && (!spi->cur_usedma))
+		mask |= STM32H7_SPI_SR_TXP | STM32H7_SPI_SR_RXP;
 
-	if (!(sr & mask)) {
+	mask &= sr;
+
+	if (!mask) {
 		dev_dbg(spi->dev, "spurious IT (sr=0x%08x, ier=0x%08x)\n",
 			sr, ier);
 		spin_unlock_irqrestore(&spi->lock, flags);
 		return IRQ_NONE;
 	}
 
-	if (sr & STM32H7_SPI_SR_SUSP) {
+	if (mask & STM32H7_SPI_SR_SUSP) {
 		dev_warn(spi->dev, "Communication suspended\n");
 		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
 			stm32h7_spi_read_rxfifo(spi, false);
@@ -918,9 +924,10 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 		 */
 		if (spi->cur_usedma)
 			end = true;
+		ifcr |= STM32H7_SPI_SR_SUSP;
 	}
 
-	if (sr & STM32H7_SPI_SR_OVR) {
+	if (mask & STM32H7_SPI_SR_OVR) {
 		dev_warn(spi->dev, "Overrun: received value discarded\n");
 		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
 			stm32h7_spi_read_rxfifo(spi, false);
@@ -930,23 +937,28 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 		 */
 		if (spi->cur_usedma)
 			end = true;
+		ifcr |= STM32H7_SPI_SR_OVR;
 	}
 
-	if (sr & STM32H7_SPI_SR_EOT) {
+	if (mask & STM32H7_SPI_SR_TXTF)
+		ifcr |= STM32H7_SPI_SR_TXTF;
+
+	if (mask & STM32H7_SPI_SR_EOT) {
 		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
 			stm32h7_spi_read_rxfifo(spi, true);
 		end = true;
+		ifcr |= STM32H7_SPI_SR_EOT;
 	}
 
-	if (sr & STM32H7_SPI_SR_TXP)
+	if (mask & STM32H7_SPI_SR_TXP)
 		if (!spi->cur_usedma && (spi->tx_buf && (spi->tx_len > 0)))
 			stm32h7_spi_write_txfifo(spi);
 
-	if (sr & STM32H7_SPI_SR_RXP)
+	if (mask & STM32H7_SPI_SR_RXP)
 		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
 			stm32h7_spi_read_rxfifo(spi, false);
 
-	writel_relaxed(mask, spi->base + STM32H7_SPI_IFCR);
+	writel_relaxed(ifcr, spi->base + STM32H7_SPI_IFCR);
 
 	spin_unlock_irqrestore(&spi->lock, flags);
 
-- 
2.7.4