linux-kernel - [PATCH v3 01/13] spi: atmel-quadspi: cache MR value to avoid a write access

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Message-ID: <20190202040653.1217-2-tudor.ambarus@microchip.com>
Date:   Sat, 2 Feb 2019 04:07:13 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <broonie@...nel.org>, <robh+dt@...nel.org>, <mark.rutland@....com>,
        <Nicolas.Ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <Ludovic.Desroches@...rochip.com>, <bbrezillon@...nel.org>,
        <Cyrille.Pitchen@...rochip.com>, <bugalski.piotr@...il.com>
CC:     <linux-spi@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-mtd@...ts.infradead.org>,
        <Tudor.Ambarus@...rochip.com>
Subject: [PATCH v3 01/13] spi: atmel-quadspi: cache MR value to avoid a write
 access

From: Tudor Ambarus <tudor.ambarus@...rochip.com>

Cache Serial Memory Mode (SMM) value to avoid write access when
setting the controller in serial memory mode. SMM is set in
exec_op() and not at probe time, to let room for future regular
SPI support.

Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
---
v3: update smm value when different. rename mr/smm
v2: cache MR value instead of moving the write access at probe

 drivers/spi/atmel-quadspi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c
index ddc712410812..645284c6ec9a 100644
--- a/drivers/spi/atmel-quadspi.c
+++ b/drivers/spi/atmel-quadspi.c
@@ -155,6 +155,7 @@ struct atmel_qspi {
 	struct clk		*clk;
 	struct platform_device	*pdev;
 	u32			pending;
+	u32			smm;
 	struct completion	cmd_completion;
 };
 
@@ -238,7 +239,11 @@ static int atmel_qspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	icr = QSPI_ICR_INST(op->cmd.opcode);
 	ifr = QSPI_IFR_INSTEN;
 
-	qspi_writel(aq, QSPI_MR, QSPI_MR_SMM);
+	/* Set the QSPI controller in Serial Memory Mode */
+	if (aq->smm != QSPI_MR_SMM) {
+		qspi_writel(aq, QSPI_MR, QSPI_MR_SMM);
+		aq->smm = QSPI_MR_SMM;
+	}
 
 	mode = find_mode(op);
 	if (mode < 0)
-- 
2.9.5