linux-kernel - [PATCH 4/5] spi: bcm-qspi: Make multiple data blocks interrupt-driven

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Date:   Mon, 15 Jun 2020 16:05:56 +1200
From:   Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>
To:     broonie@...nel.org, kdasu.kdev@...il.com
Cc:     linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
        Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>
Subject: [PATCH 4/5] spi: bcm-qspi: Make multiple data blocks interrupt-driven

When needing to send/receive data in small chunks, make this interrupt
driven rather than waiting for a completion event for each small section
of data.

Reviewed-by: Callum Sinclair <callum.sinclair@...iedtelesis.co.nz>
Reviewed-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
Signed-off-by: Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>
---
 drivers/spi/spi-bcm-qspi.c | 44 ++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/drivers/spi/spi-bcm-qspi.c b/drivers/spi/spi-bcm-qspi.c
index ce30ebf27f06..0cc51bcda300 100644
--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -200,12 +200,14 @@ struct bcm_qspi_dev_id {
 struct qspi_trans {
 	struct spi_transfer *trans;
 	int byte;
+	int slots;
 	bool mspi_last_trans;
 };
 
 struct bcm_qspi {
 	struct platform_device *pdev;
 	struct spi_master *master;
+	struct spi_device *spi_dev;
 	struct clk *clk;
 	u32 base_clk;
 	u32 max_speed_hz;
@@ -731,12 +733,14 @@ static inline u16 read_rxram_slot_u16(struct bcm_qspi *qspi, int slot)
 		((bcm_qspi_read(qspi, MSPI, msb_offset) & 0xff) << 8);
 }
 
-static void read_from_hw(struct bcm_qspi *qspi, int slots)
+static void read_from_hw(struct bcm_qspi *qspi)
 {
 	struct qspi_trans tp;
-	int slot;
+	int slot, slots;
 
 	bcm_qspi_disable_bspi(qspi);
+	tp = qspi->trans_pos;
+	slots = tp.slots;
 
 	if (slots > MSPI_NUM_CDRAM) {
 		/* should never happen */
@@ -744,8 +748,6 @@ static void read_from_hw(struct bcm_qspi *qspi, int slots)
 		return;
 	}
 
-	tp = qspi->trans_pos;
-
 	for (slot = 0; slot < slots; slot++) {
 		if (tp.trans->rx_buf) {
 			if (tp.trans->bits_per_word <= 8) {
@@ -803,11 +805,12 @@ static inline void write_cdram_slot(struct bcm_qspi *qspi, int slot, u32 val)
 }
 
 /* Return number of slots written */
-static int write_to_hw(struct bcm_qspi *qspi, struct spi_device *spi)
+static int write_to_hw(struct bcm_qspi *qspi)
 {
 	struct qspi_trans tp;
 	int slot = 0, tstatus = 0;
 	u32 mspi_cdram = 0;
+	struct spi_device *spi = qspi->spi_dev;
 
 	bcm_qspi_disable_bspi(qspi);
 	tp = qspi->trans_pos;
@@ -846,6 +849,9 @@ static int write_to_hw(struct bcm_qspi *qspi, struct spi_device *spi)
 		slot++;
 	}
 
+	/* save slot number for read_from_hw() */
+	qspi->trans_pos.slots = slot;
+
 	if (!slot) {
 		dev_err(&qspi->pdev->dev, "%s: no data to send?", __func__);
 		goto done;
@@ -960,24 +966,21 @@ static int bcm_qspi_transfer_one(struct spi_master *master,
 				 struct spi_transfer *trans)
 {
 	struct bcm_qspi *qspi = spi_master_get_devdata(master);
-	int slots;
-	unsigned long timeo = msecs_to_jiffies(100);
+	unsigned long timeo = msecs_to_jiffies(1000);
 
 	if (!spi->cs_gpiod)
 		bcm_qspi_chip_select(qspi, spi->chip_select);
 	qspi->trans_pos.trans = trans;
 	qspi->trans_pos.byte = 0;
+	qspi->spi_dev = spi;
 
-	while (qspi->trans_pos.byte < trans->len) {
-		reinit_completion(&qspi->mspi_done);
+	reinit_completion(&qspi->mspi_done);
 
-		slots = write_to_hw(qspi, spi);
-		if (!wait_for_completion_timeout(&qspi->mspi_done, timeo)) {
-			dev_err(&qspi->pdev->dev, "timeout waiting for MSPI\n");
-			return -ETIMEDOUT;
-		}
+	write_to_hw(qspi);
 
-		read_from_hw(qspi, slots);
+	if (!wait_for_completion_timeout(&qspi->mspi_done, timeo)) {
+		dev_err(&qspi->pdev->dev, "timeout waiting for MSPI\n");
+		return -ETIMEDOUT;
 	}
 	bcm_qspi_enable_bspi(qspi);
 
@@ -1092,7 +1095,16 @@ static irqreturn_t bcm_qspi_mspi_l2_isr(int irq, void *dev_id)
 		bcm_qspi_write(qspi, MSPI, MSPI_MSPI_STATUS, status);
 		if (qspi->soc_intc)
 			soc_intc->bcm_qspi_int_ack(soc_intc, MSPI_DONE);
-		complete(&qspi->mspi_done);
+
+		read_from_hw(qspi);
+
+		if (qspi->trans_pos.trans) {
+			write_to_hw(qspi);
+		} else {
+			complete(&qspi->mspi_done);
+			spi_finalize_current_transfer(qspi->master);
+		}
+
 		return IRQ_HANDLED;
 	}
 
-- 
2.27.0