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HAL_Linux: make the SPI driver much more efficient

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use a single transaction for multiple bytes. This makes the APM1
Oilpan driver generate only 2 interrupts per sensor read
This commit is contained in:
Andrew Tridgell 2013-09-29 10:15:43 +10:00
parent 7067569103
commit d3fe625742
1 changed files with 9 additions and 11 deletions
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20
libraries/AP_HAL_Linux/SPIDriver.cpp
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@ -72,18 +72,16 @@ AP_HAL::Semaphore* LinuxSPIDeviceDriver::get_semaphore()
void LinuxSPIDeviceDriver::transaction(const uint8_t *tx, uint8_t *rx, uint16_t len)
{
struct spi_ioc_transfer spi[len];
for (uint8_t i = 0; i < len ; i++) {
spi[i].tx_buf = tx?(uint64_t)(tx + i):NULL;
spi[i].rx_buf = rx?(uint64_t)(rx + i):NULL;
spi[i].len = 1;
spi[i].delay_usecs = 0;
spi[i].speed_hz = _speed;
spi[i].bits_per_word = _bitsPerWord;
spi[i].cs_change = 0;
}
struct spi_ioc_transfer spi[1];
spi[0].tx_buf = (uint64_t)tx;
spi[0].rx_buf = (uint64_t)rx;
spi[0].len = len;
spi[0].delay_usecs = 0;
spi[0].speed_hz = _speed;
spi[0].bits_per_word = _bitsPerWord;
spi[0].cs_change = 0;
ioctl(_fd, SPI_IOC_MESSAGE(len), &spi);
ioctl(_fd, SPI_IOC_MESSAGE(1), &spi);
}