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Make it non-fatal to perform SPI transfers from interrupt context.

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This commit is contained in:
px4dev 2012-08-25 13:14:01 -07:00
parent 380d136483
commit e5e2d7216c
2 changed files with 18 additions and 2 deletions
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14
apps/drivers/device/spi.cpp
View File

@ -35,8 +35,16 @@
* @file Base class for devices connected via SPI.
*
* @todo Work out if caching the mode/frequency would save any time.
*
* @todo A separate bus/device abstraction would allow for mixed interrupt-mode
* and non-interrupt-mode clients to arbitrate for the bus. As things stand,
* a bus shared between clients of both kinds is vulnerable to races between
* the two, where an interrupt-mode client will ignore the lock held by the
* non-interrupt-mode client.
*/
#include <nuttx/arch.h>
#include "spi.h"
#ifndef CONFIG_SPI_EXCHANGE
@ -124,7 +132,8 @@ SPI::transfer(uint8_t *send, uint8_t *recv, unsigned len)
return -EINVAL;
/* do common setup */
SPI_LOCK(_dev, true);
if (!up_interrupt_context())
SPI_LOCK(_dev, true);
SPI_SETFREQUENCY(_dev, _frequency);
SPI_SETMODE(_dev, _mode);
SPI_SETBITS(_dev, 8);
@ -135,7 +144,8 @@ SPI::transfer(uint8_t *send, uint8_t *recv, unsigned len)
/* and clean up */
SPI_SELECT(_dev, _device, false);
SPI_LOCK(_dev, false);
if (!up_interrupt_context())
SPI_LOCK(_dev, false);
return OK;
}

6
apps/drivers/device/spi.h
View File

@ -81,6 +81,12 @@ protected:
/**
* Perform a SPI transfer.
*
* If called from interrupt context, this interface does not lock
* the bus and may interfere with non-interrupt-context callers.
*
* Clients in a mixed interrupt/non-interrupt configuration must
* ensure appropriate interlocking.
*
* At least one of send or recv must be non-null.
*
* @param send Bytes to send to the device, or nullptr if