/**
* @brief Lock SPI bus for exclusive access
*
* On SPI buses where there are multiple devices, it will be necessary to lock
* SPI to have exclusive access to the buses for a sequence of transfers.
* The bus should be locked before the chip is selected. After locking the SPI
* bus, the caller should then also call the setfrequency(), setbpw(), and
* setmode() methods to make sure that the SPI is properly configured for the
* device. If the SPI bus is being shared, then it may have been left in an
* incompatible state.
*
* @param dev pointer to structure of device data
* @return 0 on success, negative errno on error
*/
static int tsb_spi_lock(struct device *dev)
{
struct tsb_spi_dev_info *info = NULL;
int ret = 0, loop = 0;
/* check input parameters */
if (!dev || !device_get_private(dev)) {
return -EINVAL;
}
info = device_get_private(dev);
if (info->spi_pmstate == PM_SLEEP) {
pm_activity(TSB_SPI_ACTIVITY);
/* SPI not powered, fail any accessing */;
while (info->spi_pmstate == PM_SLEEP) {
usleep(1000);
if (++loop > 10) {
return -EIO;
}
}
}
/* Take the semaphore (perhaps waiting) */
ret = sem_wait(&info->bus);
if (ret != OK) {
/* The sem_wait() call should fail only if we are awakened by
* a signal.
*/
return -get_errno();
}
info->state = TSB_SPI_STATE_LOCKED;
return 0;
}
static int gpio_pad_detect_isr(int irq, void *context)
{
pm_activity(PM_ACTIVITY);
if (work_available(&g_info->work))
work_queue(HPWORK, &g_info->work, gpio_pad_detect_worker, NULL, 0);
return OK;
}
static void button_handler(int id, int irq)
{
/* At this point the MCU should have already awakened. The state
* change will be handled in the IDLE loop when the system is re-awakened
* The button interrupt handler should be totally ignorant of the PM
* activities and should report button activity as if nothing
* special happened.
*/
pm_activity(CONFIG_PM_BUTTON_ACTIVITY);
}