linux-kernel - [RESEND][PATCH v5 3/3] mtd: devices: m25p80: add support for mmap read request

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Date:	Mon, 1 Feb 2016 12:14:25 +0530
From:	Vignesh R <vigneshr@...com>
To:	Brian Norris <computersforpeace@...il.com>,
	Mark Brown <broonie@...nel.org>
CC:	Russell King <linux@....linux.org.uk>, <hramrach@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-mtd@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
	Vignesh R <vigneshr@...com>
Subject: [RESEND][PATCH v5 3/3] mtd: devices: m25p80: add support for mmap read request

Certain spi controllers may provide accelerated interface to read from
m25p80 type flash devices. This interface provides better read
performance than regular SPI interface.
Call spi_flash_read(), if supported, to make use of such interface.

Signed-off-by: Vignesh R <vigneshr@...com>
---

Resend v5:
Rebased on top of v4.5-rc1

v5: No changes

 drivers/mtd/devices/m25p80.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index c9c3b7fa3051..7730e633d7d3 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -131,6 +131,26 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
 	/* convert the dummy cycles to the number of bytes */
 	dummy /= 8;
 
+	if (spi_flash_read_supported(spi)) {
+		struct spi_flash_read_message msg;
+		int ret;
+
+		msg.buf = buf;
+		msg.from = from;
+		msg.len = len;
+		msg.read_opcode = nor->read_opcode;
+		msg.addr_width = nor->addr_width;
+		msg.dummy_bytes = dummy;
+		/* TODO: Support other combinations */
+		msg.opcode_nbits = SPI_NBITS_SINGLE;
+		msg.addr_nbits = SPI_NBITS_SINGLE;
+		msg.data_nbits = m25p80_rx_nbits(nor);
+
+		ret = spi_flash_read(spi, &msg);
+		*retlen = msg.retlen;
+		return ret;
+	}
+
 	spi_message_init(&m);
 	memset(t, 0, (sizeof t));
 
-- 
2.7.0