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From:   Purna Chandra Mandal <purna.chandra.mandal@intel.com>
To:     Fred Bloggs <f.blogs@napier.co.nz>,
        Boris Brezillon <boris.brezillon@bootlin.com>,
        Tudor Ambarus <Tudor.Ambarus@microchip.com>
Cc:     Purna Chandra Mandal <purna.chandra.mandal@intel.com>,
        linux-kernel@vger.kernel.org, Marek Vasut <marek.vasut@gmail.com>,
        Brian Norris <computersforpeace@gmail.com>,
        Richard Weinberger <richard@nod.at>,
        linux-mtd@lists.infradead.org,
        David Woodhouse <dwmw2@infradead.org>
Subject: [PATCH] mtd: spi-nor: cadence-quadspi: write upto 8-bytes data in STIG mode
Date:   Sun, 27 Jan 2019 21:02:29 -0800
Message-Id: <20190128050229.44965-1-purna.chandra.mandal@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

cadence-quadspi controller allows upto eight bytes of data to
be written in software Triggered Instruction generator (STIG) mode
of operation. Lower 4 bytes are written through writedatalower and
upper 4 bytes by writedataupper register.

This patch allows all the 8 bytes to be written.

Signed-off-by: Purna Chandra Mandal <purna.chandra.mandal@intel.com>
---

 drivers/mtd/spi-nor/cadence-quadspi.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
index 04cedd3a2bf6..7f78f9409ddd 100644
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -418,9 +418,10 @@ static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
 	void __iomem *reg_base = cqspi->iobase;
 	unsigned int reg;
 	unsigned int data;
+	u32 write_len;
 	int ret;
 
-	if (n_tx > 4 || (n_tx && !txbuf)) {
+	if (n_tx > CQSPI_STIG_DATA_LEN_MAX || (n_tx && !txbuf)) {
 		dev_err(nor->dev,
 			"Invalid input argument, cmdlen %d txbuf 0x%p\n",
 			n_tx, txbuf);
@@ -433,10 +434,18 @@ static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
 		reg |= ((n_tx - 1) & CQSPI_REG_CMDCTRL_WR_BYTES_MASK)
 			<< CQSPI_REG_CMDCTRL_WR_BYTES_LSB;
 		data = 0;
-		memcpy(&data, txbuf, n_tx);
+		write_len = (n_tx > 4) ? 4 : n_tx;
+		memcpy(&data, txbuf, write_len);
+		txbuf += write_len;
 		writel(data, reg_base + CQSPI_REG_CMDWRITEDATALOWER);
-	}
 
+		if (n_tx > 4) {
+			data = 0;
+			write_len = n_tx - 4;
+			memcpy(&data, txbuf, write_len);
+			writel(data, reg_base + CQSPI_REG_CMDWRITEDATAUPPER);
+		}
+	}
 	ret = cqspi_exec_flash_cmd(cqspi, reg);
 	return ret;
 }
-- 
2.13.0