SPIDevice::SPIDevice(SPIBus &bus, SPIDesc &device_desc)
: _bus(bus)
, _desc(device_desc)
{
set_device_bus(_bus.bus);
set_device_address(_desc.subdev);
if (_desc.cs_pin != SPI_CS_KERNEL) {
_cs = hal.gpio->channel(_desc.cs_pin);
if (!_cs) {
AP_HAL::panic("Unable to instantiate cs pin");
}
_cs->mode(HAL_GPIO_OUTPUT);
// do not hold the SPI bus initially
_cs_release();
}
}
bool SPIDevice::transfer_fullduplex(const uint8_t *send, uint8_t *recv,
uint32_t len)
{
struct spi_ioc_transfer msgs[1] = { };
assert(_bus.fd >= 0);
if (!send || !recv || len == 0) {
return false;
}
msgs[0].tx_buf = (uint64_t) send;
msgs[0].rx_buf = (uint64_t) recv;
msgs[0].len = len;
msgs[0].speed_hz = _speed;
msgs[0].delay_usecs = 0;
msgs[0].bits_per_word = _desc.bits_per_word;
msgs[0].cs_change = 0;
int r = ioctl(_bus.fd, SPI_IOC_WR_MODE, &_desc.mode);
if (r < 0) {
hal.console->printf("SPIDevice: error on setting mode fd=%d (%s)\n",
_bus.fd, strerror(errno));
return false;
}
_cs_assert();
r = ioctl(_bus.fd, SPI_IOC_MESSAGE(1), &msgs);
_cs_release();
if (r == -1) {
hal.console->printf("SPIDevice: error transferring data fd=%d (%s)\n",
_bus.fd, strerror(errno));
return false;
}
return true;
}
bool SPIDevice::transfer(const uint8_t *send, uint32_t send_len,
uint8_t *recv, uint32_t recv_len)
{
struct spi_ioc_transfer msgs[2] = { };
unsigned nmsgs = 0;
assert(_bus.fd >= 0);
if (send && send_len != 0) {
msgs[nmsgs].tx_buf = (uint64_t) send;
msgs[nmsgs].rx_buf = 0;
msgs[nmsgs].len = send_len;
msgs[nmsgs].speed_hz = _speed;
msgs[nmsgs].delay_usecs = 0;
msgs[nmsgs].bits_per_word = _desc.bits_per_word;
msgs[nmsgs].cs_change = 0;
nmsgs++;
}
if (recv && recv_len != 0) {
msgs[nmsgs].tx_buf = 0;
msgs[nmsgs].rx_buf = (uint64_t) recv;
msgs[nmsgs].len = recv_len;
msgs[nmsgs].speed_hz = _speed;
msgs[nmsgs].delay_usecs = 0;
msgs[nmsgs].bits_per_word = _desc.bits_per_word;
msgs[nmsgs].cs_change = 0;
nmsgs++;
}
if (!nmsgs) {
return false;
}
int r;
if (_bus.last_mode == _desc.mode) {
/*
the mode in the kernel is not tied to the file descriptor,
so there is a chance some other process has changed it since
we last used the bus. We want to report when this happens so
the user has a chance of figuring out when there is
conflicted use of the SPI bus. Unfortunately this costs us
an extra syscall per transfer.
*/
uint8_t current_mode;
if (ioctl(_bus.fd, SPI_IOC_RD_MODE, ¤t_mode) < 0) {
hal.console->printf("SPIDevice: error on getting mode fd=%d (%s)\n",
_bus.fd, strerror(errno));
_bus.last_mode = -1;
} else if (current_mode != _bus.last_mode) {
hal.console->printf("SPIDevice: bus mode conflict fd=%d mode=%u/%u\n",
_bus.fd, (unsigned)_bus.last_mode, (unsigned)current_mode);
_bus.last_mode = -1;
}
}
if (_desc.mode != _bus.last_mode) {
r = ioctl(_bus.fd, SPI_IOC_WR_MODE, &_desc.mode);
if (r < 0) {
hal.console->printf("SPIDevice: error on setting mode fd=%d (%s)\n",
_bus.fd, strerror(errno));
return false;
}
_bus.last_mode = _desc.mode;
}
_cs_assert();
r = ioctl(_bus.fd, SPI_IOC_MESSAGE(nmsgs), &msgs);
_cs_release();
if (r == -1) {
hal.console->printf("SPIDevice: error transferring data fd=%d (%s)\n",
_bus.fd, strerror(errno));
return false;
}
return true;
}
