mrf24j40: async interrupt handling

This patch removes the threaded irq handling and do a hardirq instead.
We need to switch to spi_async for this step for getting the irq status
register.
Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/net/ieee802154/mrf24j40.c

@@ -181,8 +181,10 @@ struct mrf24j40 {
 	u8 rx_fifo_buf[RX_FIFO_SIZE];
 	struct spi_transfer rx_fifo_buf_trx;
 
-	struct mutex buffer_mutex; /* only used to protect buf */
-	u8 *buf; /* 3 bytes. Used for SPI single-register transfers. */
+	/* isr handling for reading intstat */
+	struct spi_message irq_msg;
+	u8 irq_buf[2];
+	struct spi_transfer irq_trx;
 };
 
 /* regmap information for short address register access */
@@ -486,34 +488,6 @@ static const struct regmap_bus mrf24j40_long_regmap_bus = {
 	.val_format_endian_default = REGMAP_ENDIAN_BIG,
 };
 
-static int read_short_reg(struct mrf24j40 *devrec, u8 reg, u8 *val)
-{
-	int ret = -1;
-	struct spi_message msg;
-	struct spi_transfer xfer = {
-		.len = 2,
-		.tx_buf = devrec->buf,
-		.rx_buf = devrec->buf,
-	};
-
-	spi_message_init(&msg);
-	spi_message_add_tail(&xfer, &msg);
-
-	mutex_lock(&devrec->buffer_mutex);
-	devrec->buf[0] = MRF24J40_READSHORT(reg);
-	devrec->buf[1] = 0;
-
-	ret = spi_sync(devrec->spi, &msg);
-	if (ret)
-		dev_err(printdev(devrec),
-			"SPI read Failed for short register 0x%hhx\n", reg);
-	else
-		*val = devrec->buf[1];
-
-	mutex_unlock(&devrec->buffer_mutex);
-	return ret;
-}
-
 static void write_tx_buf_complete(void *context)
 {
 	struct mrf24j40 *devrec = context;
@@ -812,16 +786,12 @@ static const struct ieee802154_ops mrf24j40_ops = {
 	.set_hw_addr_filt = mrf24j40_filter,
 };
 
-static irqreturn_t mrf24j40_isr(int irq, void *data)
+static void mrf24j40_intstat_complete(void *context)
 {
-	struct mrf24j40 *devrec = data;
-	u8 intstat;
-	int ret;
+	struct mrf24j40 *devrec = context;
+	u8 intstat = devrec->irq_buf[1];
 
-	/* Read the interrupt status */
-	ret = read_short_reg(devrec, REG_INTSTAT, &intstat);
-	if (ret)
-		goto out;
+	enable_irq(devrec->spi->irq);
 
 	/* Check for TX complete */
 	if (intstat & 0x1)
@@ -830,8 +800,23 @@ static irqreturn_t mrf24j40_isr(int irq, void *data)
 	/* Check for Rx */
 	if (intstat & 0x8)
 		mrf24j40_handle_rx(devrec);
+}
+
+static irqreturn_t mrf24j40_isr(int irq, void *data)
+{
+	struct mrf24j40 *devrec = data;
+	int ret;
+
+	disable_irq_nosync(irq);
+
+	devrec->irq_buf[0] = MRF24J40_READSHORT(REG_INTSTAT);
+	/* Read the interrupt status */
+	ret = spi_async(devrec->spi, &devrec->irq_msg);
+	if (ret) {
+		enable_irq(irq);
+		return IRQ_NONE;
+	}
 
-out:
 	return IRQ_HANDLED;
 }
 
@@ -978,6 +963,18 @@ mrf24j40_setup_rx_spi_messages(struct mrf24j40 *devrec)
 	spi_message_add_tail(&devrec->rx_lqi_trx, &devrec->rx_buf_msg);
 }
 
+static void
+mrf24j40_setup_irq_spi_messages(struct mrf24j40 *devrec)
+{
+	spi_message_init(&devrec->irq_msg);
+	devrec->irq_msg.context = devrec;
+	devrec->irq_msg.complete = mrf24j40_intstat_complete;
+	devrec->irq_trx.len = 2;
+	devrec->irq_trx.tx_buf = devrec->irq_buf;
+	devrec->irq_trx.rx_buf = devrec->irq_buf;
+	spi_message_add_tail(&devrec->irq_trx, &devrec->irq_msg);
+}
+
 static void  mrf24j40_phy_setup(struct mrf24j40 *devrec)
 {
 	ieee802154_random_extended_addr(&devrec->hw->phy->perm_extended_addr);
@@ -1008,6 +1005,7 @@ static int mrf24j40_probe(struct spi_device *spi)
 
 	mrf24j40_setup_tx_spi_messages(devrec);
 	mrf24j40_setup_rx_spi_messages(devrec);
+	mrf24j40_setup_irq_spi_messages(devrec);
 
 	devrec->regmap_short = devm_regmap_init_spi(spi,
 						    &mrf24j40_short_regmap);
@@ -1028,32 +1026,21 @@ static int mrf24j40_probe(struct spi_device *spi)
 		goto err_register_device;
 	}
 
-	devrec->buf = devm_kzalloc(&spi->dev, 3, GFP_KERNEL);
-	if (!devrec->buf)
-		goto err_register_device;
-
 	if (spi->max_speed_hz > MAX_SPI_SPEED_HZ) {
 		dev_warn(&spi->dev, "spi clock above possible maximum: %d",
 			 MAX_SPI_SPEED_HZ);
 		return -EINVAL;
 	}
 
-	mutex_init(&devrec->buffer_mutex);
-
 	ret = mrf24j40_hw_init(devrec);
 	if (ret)
 		goto err_register_device;
 
 	mrf24j40_phy_setup(devrec);
 
-	ret = devm_request_threaded_irq(&spi->dev,
-					spi->irq,
-					NULL,
-					mrf24j40_isr,
-					IRQF_TRIGGER_LOW|IRQF_ONESHOT,
-					dev_name(&spi->dev),
+	ret = devm_request_irq(&spi->dev, spi->irq, mrf24j40_isr,
+			       IRQF_TRIGGER_LOW, dev_name(&spi->dev),
 			       devrec);
-
 	if (ret) {
 		dev_err(printdev(devrec), "Unable to get IRQ");
 		goto err_register_device;