linux-kernel - [PATCH v4 3/5] mtd: devices: m25p80: add support for mmap read request

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Message-ID: <1448860515-28336-4-git-send-email-vigneshr@ti.com>
Date:	Mon, 30 Nov 2015 10:45:13 +0530
From:	Vignesh R <vigneshr@...com>
To:	Tony Lindgren <tony@...mide.com>,
	Brian Norris <computersforpeace@...il.com>,
	Mark Brown <broonie@...nel.org>
CC:	Rob Herring <robh+dt@...nel.org>,
	Russell King <linux@....linux.org.uk>, <hramrach@...il.com>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mtd@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
	Vignesh R <vigneshr@...com>
Subject: [PATCH v4 3/5] 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>
---

v4: 
 * Use spi_flash_read_message struct to pass args.
 * support passing of opcode/addr/data nbits.

 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 fe9ceb7b5405..00094a668c62 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));
 
-- 
2.6.3

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