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spi: Add SPI transfer function that pass in RX/TX

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When using SPI, I prefer to not have to do malloc/free functions for each
transfer, so why not have a transfer function that you can pass in both
buffers.  With my ILI9341 TFT display code that gave some perf wins, also more
of a win, you can pass in NULL for recv buffer and the underlying device driver
does not have to copy the data.

Signed-off-by: Kurt Eckhardt <kurte@rockisland.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
This commit is contained in:
Kurt Eckhardt
2014-10-18 09:25:19 -07:00
committed by Brendan Le Foll
parent 54deb01796
commit 2a11e31052
4 changed files with 53 additions and 5 deletions
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11
api/mraa/spi.h
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@@ -105,6 +105,17 @@ uint8_t mraa_spi_write(mraa_spi_context dev, uint8_t data);
*/
uint8_t* mraa_spi_write_buf(mraa_spi_context dev, uint8_t* data, int length);
/** Transfer Buffer of bytes to the SPI device. Both send and recv buffers
* are passed in
*
* @param dev The Spi context
* @param data to send
* @param rxbuf buffer to recv data back, may be NULL
* @param length elements within buffer, Max 4096
* @return Result of operation
*/
mraa_result_t mraa_spi_transfer_buf(mraa_spi_context dev, uint8_t* data, uint8_t* rxbuf, int length);
/**
* Change the SPI lsb mode
*

15
api/mraa/spi.hpp
View File

@@ -84,7 +84,8 @@ class Spi {
return (char) mraa_spi_write(m_spi, (uint8_t) data);
}
/**
* Write buffer of bytes to SPI device
* Write buffer of bytes to SPI device The pointer return has to be
* free'd by the caller.
*
* @param data buffer to send
* @param length size of buffer to send
@@ -93,6 +94,18 @@ class Spi {
char* write(char* data, size_t length) {
return (char*) mraa_spi_write_buf(m_spi, (uint8_t *) data, (int) length);
}
/**
* Transfer data to and from SPI device Receive pointer may be null if return
* data is not needed.
*
* @param data buffer to send
* @param rxBuf buffer to optionally receive data from spi device
* @param length size of buffer to send
* @return Result of operation
*/
mraa_result_t transfer(char* data, char* rxBuf, size_t length) {
return mraa_spi_transfer_buf(m_spi, (uint8_t *) data, (uint8_t *)rxBuf, (int) length);
}
/**
* Change the SPI lsb mode
*