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

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Date:	Tue, 29 Mar 2016 11:16:17 +0530
From:	Vignesh R <vigneshr@...com>
To:	Brian Norris <computersforpeace@...il.com>
CC:	David Woodhouse <dwmw2@...radead.org>, Vignesh R <vigneshr@...com>,
	<linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request

Certain SPI controllers may provide accelerated hardware interface to
read from m25p80 type flash devices in order to provide better read
performance. SPI core supports such devices with spi_flash_read() API.
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 v4.6-rc1
v5: http://www.spinics.net/lists/devicetree/msg106696.html

 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));
 
-- 
2.7.4