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authorVignesh R <vigneshr@ti.com>2015-12-11 09:39:56 +0530
committerMark Brown <broonie@kernel.org>2016-02-09 19:34:02 +0000
commit556351f14e74db4cd3ddde386457edce7bf0b27f (patch)
treed0f00feb603a841a6bd44929941cb1d7da1eabef /include/linux/spi
parent92e963f50fc74041b5e9e744c330dca48e04f08d (diff)
downloadop-kernel-dev-556351f14e74db4cd3ddde386457edce7bf0b27f.zip
op-kernel-dev-556351f14e74db4cd3ddde386457edce7bf0b27f.tar.gz
spi: introduce accelerated read support for spi flash devices
In addition to providing direct access to SPI bus, some spi controller hardwares (like ti-qspi) provide special port (like memory mapped port) that are optimized to improve SPI flash read performance. This means the controller can automatically send the SPI signals required to read data from the SPI flash device. For this, SPI controller needs to know flash specific information like read command to use, dummy bytes and address width. Introduce spi_flash_read() interface to support accelerated read over SPI flash devices. SPI master drivers can implement this callback to support interfaces such as memory mapped read etc. m25p80 flash driver and other flash drivers can call this make use of such interfaces. The interface should only be used with SPI flashes and cannot be used with other SPI devices. Signed-off-by: Vignesh R <vigneshr@ti.com> Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'include/linux/spi')
-rw-r--r--include/linux/spi/spi.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 53be3a4..ba0dee9 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -25,6 +25,7 @@
struct dma_chan;
struct spi_master;
struct spi_transfer;
+struct spi_flash_read_message;
/*
* INTERFACES between SPI master-side drivers and SPI infrastructure.
@@ -361,6 +362,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
* @handle_err: the subsystem calls the driver to handle an error that occurs
* in the generic implementation of transfer_one_message().
* @unprepare_message: undo any work done by prepare_message().
+ * @spi_flash_read: to support spi-controller hardwares that provide
+ * accelerated interface to read from flash devices.
* @cs_gpios: Array of GPIOs to use as chip select lines; one per CS
* number. Any individual value may be -ENOENT for CS lines that
* are not GPIOs (driven by the SPI controller itself).
@@ -513,6 +516,8 @@ struct spi_master {
struct spi_message *message);
int (*unprepare_message)(struct spi_master *master,
struct spi_message *message);
+ int (*spi_flash_read)(struct spi_device *spi,
+ struct spi_flash_read_message *msg);
/*
* These hooks are for drivers that use a generic implementation
@@ -1019,6 +1024,42 @@ static inline ssize_t spi_w8r16be(struct spi_device *spi, u8 cmd)
return be16_to_cpu(result);
}
+/**
+ * struct spi_flash_read_message - flash specific information for
+ * spi-masters that provide accelerated flash read interfaces
+ * @buf: buffer to read data
+ * @from: offset within the flash from where data is to be read
+ * @len: length of data to be read
+ * @retlen: actual length of data read
+ * @read_opcode: read_opcode to be used to communicate with flash
+ * @addr_width: number of address bytes
+ * @dummy_bytes: number of dummy bytes
+ * @opcode_nbits: number of lines to send opcode
+ * @addr_nbits: number of lines to send address
+ * @data_nbits: number of lines for data
+ */
+struct spi_flash_read_message {
+ void *buf;
+ loff_t from;
+ size_t len;
+ size_t retlen;
+ u8 read_opcode;
+ u8 addr_width;
+ u8 dummy_bytes;
+ u8 opcode_nbits;
+ u8 addr_nbits;
+ u8 data_nbits;
+};
+
+/* SPI core interface for flash read support */
+static inline bool spi_flash_read_supported(struct spi_device *spi)
+{
+ return spi->master->spi_flash_read ? true : false;
+}
+
+int spi_flash_read(struct spi_device *spi,
+ struct spi_flash_read_message *msg);
+
/*---------------------------------------------------------------------------*/
/*
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