File content as of revision 3:25de898f5354:

#include "mbed_assert.h"
#include "mbed_error.h"
#include "stm_i2s_api.h"

#include "stm_dma_caps.h"

#if DEVICE_I2S

#include <math.h>
#include <string.h>
#include "cmsis.h"
#include "pinmap.h"
#include "PeripheralPins.h"
#include "StmI2sPeripheralPins.h"

//#define DEBUG_STDIO 1 // betzw - TODO: temporarily enable debug printfs

#ifndef DEBUG_STDIO
#   define DEBUG_STDIO 0
#endif

#if DEBUG_STDIO
#   include <stdio.h>
#   define DEBUG_PRINTF(...) do { printf(__VA_ARGS__); } while(0)
#else
#   define DEBUG_PRINTF(...) {}
#endif

typedef enum {
    I2S_TRANSFER_TYPE_TX = 1,
    I2S_TRANSFER_TYPE_RX = 2,
    I2S_TRANSFER_TYPE_TXRX = 3,
} transfer_type_t;

typedef struct {
    DMA_HandleTypeDef tx_dma_handle;
    DMA_HandleTypeDef rx_dma_handle;
} dma_handles_t;

#define I2S_NUM (5) // betzw: this approach wastes quite a bit of memory - TO BE IMPROVED!?!?

static I2S_HandleTypeDef I2sHandle[I2S_NUM];
static DMA_HandleTypeDef DMaHandles[I2S_NUM][NUM_OF_DIRECTIONS];

static void init_i2s(i2s_t *obj) {
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];

    __HAL_I2S_DISABLE(handle);
    HAL_I2S_Init(handle);
    __HAL_I2S_ENABLE(handle);
}

static void init_dmas(i2s_t *obj) {
    DMA_HandleTypeDef *primary_handle = NULL;
    DMA_HandleTypeDef *secondary_handle = NULL;
    DMA_HandleTypeDef *hdmatx = NULL;

    switch(obj->dma.dma_direction) {
	    case DMA_TX:
			if(obj->dma.dma[DMA_TX] != NULL) {
			    hdmatx = primary_handle = &DMaHandles[obj->i2s.module][DMA_TX];
			}
			if(obj->dma.dma[DMA_RX] != NULL) {
			    secondary_handle = &DMaHandles[obj->i2s.module][DMA_RX];
			}
			break;
	    case DMA_RX:
    	default:
			if(obj->dma.dma[DMA_RX] != NULL) {
			    primary_handle = &DMaHandles[obj->i2s.module][DMA_RX];
			}
			if(obj->dma.dma[DMA_TX] != NULL) {
			    hdmatx = secondary_handle = &DMaHandles[obj->i2s.module][DMA_TX];
			}
			break;
    }

    if(primary_handle != NULL) {
		__HAL_DMA_DISABLE(primary_handle);
		HAL_DMA_Init(primary_handle);

		if(hdmatx == primary_handle) {
		    __HAL_LINKDMA(&I2sHandle[obj->i2s.module], hdmatx, *primary_handle);
		} else {
		    __HAL_LINKDMA(&I2sHandle[obj->i2s.module], hdmarx, *primary_handle);
		}
    }

    if(secondary_handle != NULL) {
		__HAL_DMA_DISABLE(secondary_handle);
		HAL_DMA_Init(secondary_handle);

		if(hdmatx == secondary_handle) {
		    __HAL_LINKDMA(&I2sHandle[obj->i2s.module], hdmatx, *secondary_handle);
		} else {
		    __HAL_LINKDMA(&I2sHandle[obj->i2s.module], hdmarx, *secondary_handle);
		}
    }
}

static inline uint32_t i2s_get_mode(i2s_mode_t mode, uint8_t *direction) {
    switch(mode) {
	    case SLAVE_TX:
			*direction = DMA_TX;
			return I2S_MODE_SLAVE_TX;
	    case SLAVE_RX:
			*direction = DMA_RX;
			return I2S_MODE_SLAVE_RX;
	    case MASTER_TX:
			*direction = DMA_TX;
			return I2S_MODE_MASTER_TX;
	    case MASTER_RX:
	    default:
			*direction = DMA_RX;
			return I2S_MODE_MASTER_RX;
    }
}

static inline uint32_t i2s_get_priority(i2s_dma_prio_t priority) {
    switch(priority) {
	    case LOW:
			return DMA_PRIORITY_LOW;
	    case URGENT:
			return DMA_PRIORITY_VERY_HIGH;
	    case HIGH:
			return DMA_PRIORITY_HIGH;
	    default:
			return DMA_PRIORITY_MEDIUM;
    }
}

static void dma_i2s_init(i2s_t *obj, bool *use_tx, bool *use_rx, bool circular, i2s_dma_prio_t prio) {
    // DMA declarations
    DMA_HandleTypeDef *primary_handle = &DMaHandles[obj->i2s.module][obj->dma.dma_direction];
    DMA_HandleTypeDef *secondary_handle = NULL;

    // DMA initialization & configuration
    stm_dma_init();
    obj->dma.dma[DMA_TX] = obj->dma.dma[DMA_RX] = NULL;

    switch(obj->dma.dma_direction) {
	    case DMA_TX:
			if(*use_tx) {
			    obj->dma.dma[DMA_TX] = stm_dma_channel_allocate(MAKE_CAP(obj->dma.dma_device, DMA_TX));
			    MBED_ASSERT(obj->dma.dma[DMA_TX] != DMA_ERROR_OUT_OF_CHANNELS);
			}
			break;
	    case DMA_RX:
	    default:
			if(*use_rx) {
			    obj->dma.dma[DMA_RX] = stm_dma_channel_allocate(MAKE_CAP(obj->dma.dma_device, DMA_RX));
			    MBED_ASSERT(obj->dma.dma[DMA_RX] != DMA_ERROR_OUT_OF_CHANNELS);
			}
			break;
    }

    // Primary DMA configuration
    if(obj->dma.dma[obj->dma.dma_direction] != NULL) {
		primary_handle->Instance = obj->dma.dma[obj->dma.dma_direction]->dma_stream;
		primary_handle->Init.Channel = obj->dma.dma[obj->dma.dma_direction]->channel_nr;
		primary_handle->Init.Direction = (obj->dma.dma_direction == DMA_TX) ? 
		    DMA_MEMORY_TO_PERIPH : DMA_PERIPH_TO_MEMORY;
		primary_handle->Init.FIFOMode = DMA_FIFOMODE_DISABLE;
		primary_handle->Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
		primary_handle->Init.MemBurst = DMA_MBURST_SINGLE;
		primary_handle->Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
		primary_handle->Init.MemInc = DMA_MINC_ENABLE;
		primary_handle->Init.Mode = (circular ? DMA_CIRCULAR : DMA_NORMAL);
		primary_handle->Init.PeriphBurst = DMA_PBURST_SINGLE;
		primary_handle->Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;
		primary_handle->Init.PeriphInc = DMA_PINC_DISABLE;
		primary_handle->Init.Priority = i2s_get_priority(prio);
    }

    // Allocate secondary DMA channel (if full-duplex)
    if(obj->i2s.pin_fdpx != NC) {
		switch(obj->dma.dma_direction) {
			case DMA_TX:
			    if(*use_rx) {
				obj->dma.dma[DMA_RX] = stm_dma_channel_allocate(MAKE_CAP(obj->dma.dma_device, DMA_RX));
				secondary_handle = &DMaHandles[obj->i2s.module][DMA_RX];
				MBED_ASSERT(obj->dma.dma[DMA_RX] != DMA_ERROR_OUT_OF_CHANNELS);
			    }
			    break;
			case DMA_RX:
			default:
			    if(*use_tx) {
				obj->dma.dma[DMA_TX] = stm_dma_channel_allocate(MAKE_CAP(obj->dma.dma_device, DMA_TX));
				secondary_handle = &DMaHandles[obj->i2s.module][DMA_TX];
				MBED_ASSERT(obj->dma.dma[DMA_TX] != DMA_ERROR_OUT_OF_CHANNELS);
			    }
			    break;
		}
    }

    // Secondary DMA configuration
    if(secondary_handle != NULL) {
		uint8_t secondary_dma_direction = (obj->dma.dma_direction == DMA_TX) ? DMA_RX : DMA_TX;

		secondary_handle->Instance = obj->dma.dma[secondary_dma_direction]->dma_stream;
		secondary_handle->Init.Channel = obj->dma.dma[secondary_dma_direction]->channel_nr_fd;
		secondary_handle->Init.Direction = (secondary_dma_direction == DMA_TX) ? 
		    DMA_MEMORY_TO_PERIPH : DMA_PERIPH_TO_MEMORY;
		secondary_handle->Init.FIFOMode = DMA_FIFOMODE_DISABLE;
		secondary_handle->Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
		secondary_handle->Init.MemBurst = DMA_MBURST_SINGLE;
		secondary_handle->Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
		secondary_handle->Init.MemInc = DMA_MINC_ENABLE;
		secondary_handle->Init.Mode = (circular ? DMA_CIRCULAR : DMA_NORMAL);
		secondary_handle->Init.PeriphBurst = DMA_PBURST_SINGLE;
		secondary_handle->Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;
		secondary_handle->Init.PeriphInc = DMA_PINC_DISABLE;
		secondary_handle->Init.Priority = i2s_get_priority(prio);
    }

    if(obj->dma.dma[DMA_TX] == NULL) *use_tx = false;
    if(obj->dma.dma[DMA_RX] == NULL) *use_rx = false;

    // don't do anything, if the buffers aren't valid
    if (!use_tx && !use_rx) {
		DEBUG_PRINTF("    I2S%u: No DMAs to init\r\n", obj->i2s.module + 1);
		return;
    }

    DEBUG_PRINTF("    I2S%u: DMA(s) Init\r\n", obj->i2s.module + 1);

    init_dmas(obj);
}

static void dma_i2s_free(i2s_t *obj, uint8_t direction) {
    const struct dma_stream_s *stream = obj->dma.dma[direction];

    MBED_ASSERT(stream != NULL);

    // disable irq
    NVIC_DisableIRQ(stream->dma_stream_irq);

    // free channel
    stm_dma_channel_free((void*)stream);
    obj->dma.dma[direction] = NULL;
}

void i2s_init(i2s_t *obj, PinName data, PinName sclk, PinName wsel, PinName fdpx, PinName mclk, i2s_mode_t mode) {
    uint8_t dma_dev = 0, dma_direction = 0;

    // Determine the I2S/SPI to use
    SPIName i2s_data = (SPIName)pinmap_peripheral(data, PinMap_I2S_DATA);
    SPIName i2s_sclk = (SPIName)pinmap_peripheral(sclk, PinMap_I2S_SCLK);

    SPIName i2s_wsel = (SPIName)pinmap_peripheral(wsel, PinMap_I2S_WSEL);
    SPIName i2s_fdpx = (SPIName)pinmap_peripheral(fdpx, PinMap_I2S_FDPX);

    SPIName i2s_mclk = (SPIName)pinmap_peripheral(mclk, PinMap_I2S_MCLK);

    SPIName i2s_merge1 = (SPIName)pinmap_merge(i2s_data, i2s_sclk);
    SPIName i2s_merge2 = (SPIName)pinmap_merge(i2s_wsel, i2s_fdpx);

    SPIName i2s_merge3 = (SPIName)pinmap_merge(i2s_merge1, i2s_merge2);
    SPIName instance   = (SPIName)pinmap_merge(i2s_merge3, i2s_mclk);
    MBED_ASSERT(instance != (SPIName)NC);

    // Enable I2S/SPI clock and set the right module number
    switch(instance) {
#if defined(I2S1ext_BASE)
    case SPI_1:
	__SPI1_CLK_ENABLE();
	obj->i2s.module = 0;
	dma_dev = DMA_SPI1;
	break;
#endif
#if defined(I2S2ext_BASE)
    case SPI_2:
	__SPI2_CLK_ENABLE();
	obj->i2s.module = 1;
	dma_dev = DMA_SPI2;
	break;
#endif
#if defined(I2S3ext_BASE)
    case SPI_3:
	__SPI3_CLK_ENABLE();
	obj->i2s.module = 2;
	dma_dev = DMA_SPI3;
	break;
#endif
#if defined(I2S4ext_BASE)
    case SPI_4:
	__SPI4_CLK_ENABLE();
	obj->i2s.module = 3;
	dma_dev = DMA_SPI4;
	break;
#endif
#if defined(I2S5ext_BASE)
    case SPI_5:
	__SPI5_CLK_ENABLE();
	obj->i2s.module = 4;
	dma_dev = DMA_SPI5;
	break;
#endif
    default:
	MBED_ASSERT(0);
	break;
    }

    // Save DMA device
    obj->dma.dma_device = dma_dev;

    // Configure the I2S pins
    pinmap_pinout(data, PinMap_I2S_DATA);
    pinmap_pinout(wsel, PinMap_I2S_WSEL);
    pinmap_pinout(sclk, PinMap_I2S_SCLK);
    pinmap_pinout(fdpx, PinMap_I2S_FDPX);
    pinmap_pinout(mclk, PinMap_I2S_MCLK);

    obj->i2s.pin_wsel = wsel;
    obj->i2s.pin_data = data;
    obj->i2s.pin_sclk = sclk;
    obj->i2s.pin_fdpx = fdpx;
    obj->i2s.pin_mclk = mclk;

	/* Configure PLLI2S */
    static bool first_time = true;
    if (first_time)
    {
		RCC_PeriphCLKInitTypeDef PeriphClkInitStruct;

		/* Get RTCClockSelection */
		HAL_RCCEx_GetPeriphCLKConfig(&PeriphClkInitStruct);

		/* Set default configuration. Default frequency is 44100Hz. */
		PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_I2S;
		PeriphClkInitStruct.PLLI2S.PLLI2SN = 213; //Davide: use values which are suggested in Table 91 of the
		PeriphClkInitStruct.PLLI2S.PLLI2SR = 2;   //        reference manual for master clock enabled & 32000Hz.

#ifdef NDEBUG
		HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);
#else
		HAL_StatusTypeDef ret = HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);
#endif
		MBED_ASSERT(ret == HAL_OK);

		first_time = false;
    }

    /* Initializing the handle for this master. */
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];

    handle->Instance               = (SPI_TypeDef *)(instance);
    handle->Init.Mode              = i2s_get_mode(mode, &dma_direction);
    handle->Init.Standard          = I2S_STANDARD_PCM_SHORT;
    handle->Init.DataFormat        = I2S_DATAFORMAT_16B;
    handle->Init.CPOL              = I2S_CPOL_LOW;
    handle->Init.AudioFreq         = I2S_AUDIOFREQ_32K; //Davide: Default frequency is 32000Hz.
    handle->Init.ClockSource       = I2S_CLOCK_PLL;
    handle->Init.FullDuplexMode    = (fdpx == NC ? I2S_FULLDUPLEXMODE_DISABLE : I2S_FULLDUPLEXMODE_ENABLE);
	handle->Init.MCLKOutput        = (mclk == NC ? I2S_MCLKOUTPUT_DISABLE : I2S_MCLKOUTPUT_ENABLE); //Davide: Microphones need master clock disabled, while sound terminal needs it enabled.

    DEBUG_PRINTF("--> %s\r\n", __FUNCTION__);
    DEBUG_PRINTF("    I2S%u: Mode: %u (%u)\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.Mode, (unsigned int)mode);
    DEBUG_PRINTF("    I2S%u: Standard: %u\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.Standard);
    DEBUG_PRINTF("    I2S%u: DataFormat: %u\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.DataFormat);
    DEBUG_PRINTF("    I2S%u: CPOL: %u\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.CPOL);
    DEBUG_PRINTF("    I2S%u: AudioFreq: %u\r\n", obj->i2s.module + 1,
    	(unsigned int)handle->Init.AudioFreq);
    DEBUG_PRINTF("    I2S%u: ClockSource: %u\r\n", obj->i2s.module + 1,
    	(unsigned int)handle->Init.ClockSource);
    DEBUG_PRINTF("    I2S%u: FullDuplexMode: %u\r\n", obj->i2s.module + 1,
    	(unsigned int)handle->Init.FullDuplexMode);
    DEBUG_PRINTF("    I2S%u: MCLKOutput: %u\r\n", obj->i2s.module + 1,
    	(unsigned int)handle->Init.MCLKOutput);

    // Save primary DMA direction
    obj->dma.dma_direction = dma_direction;

    init_i2s(obj);
}

void i2s_free(i2s_t *obj) {
    // Reset I2S and disable clock
    switch(obj->i2s.module) {
#if defined(I2S1ext_BASE)
	    case 0:
			__SPI1_FORCE_RESET();
			__SPI1_RELEASE_RESET();
			__SPI1_CLK_DISABLE();
			break;
#endif
#if defined(I2S2ext_BASE)
	    case 1:
			__SPI2_FORCE_RESET();
			__SPI2_RELEASE_RESET();
			__SPI2_CLK_DISABLE();
			break;
#endif
#if defined(I2S3ext_BASE)
	    case 2:
			__SPI3_FORCE_RESET();
			__SPI3_RELEASE_RESET();
			__SPI3_CLK_DISABLE();
			break;
#endif
#if defined(I2S4ext_BASE)
	    case 3:
			__SPI4_FORCE_RESET();
			__SPI4_RELEASE_RESET();
			__SPI4_CLK_DISABLE();
			break;
#endif
#if defined(I2S5ext_BASE)
	    case 4:
			__SPI5_FORCE_RESET();
			__SPI5_RELEASE_RESET();
			__SPI5_CLK_DISABLE();
			break;
#endif
	    default:
			MBED_ASSERT(0);
			break;
    }

    // betzw - TODO: what about 'PLLI2S'?!?
    //               for the moment we leave it enabled!

    // Configure GPIOs
    pin_function(obj->i2s.pin_wsel, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
    pin_function(obj->i2s.pin_data, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
    pin_function(obj->i2s.pin_sclk, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
    pin_function(obj->i2s.pin_fdpx, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
    pin_function(obj->i2s.pin_mclk, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));

    DEBUG_PRINTF("--> %s\r\n", __FUNCTION__);
}

void i2s_format(i2s_t *obj, int dbits, int fbits, int polarity) {
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];

    // Save new values
    if (fbits == 16)
    { // format MUST be 16B
		handle->Init.DataFormat = I2S_DATAFORMAT_16B;
    } else { // format may NOT be 16B
		switch (dbits)
		{
			case 16:
			    handle->Init.DataFormat = I2S_DATAFORMAT_16B_EXTENDED;
			    break;
			case 24:
			    handle->Init.DataFormat = I2S_DATAFORMAT_24B;
			    break;
			case 32:
			default:
			    handle->Init.DataFormat = I2S_DATAFORMAT_32B;
			    break;
		}
    }

    handle->Init.CPOL = (polarity == 0) ? I2S_CPOL_LOW : I2S_CPOL_HIGH;

    DEBUG_PRINTF("--> %s\r\n", __FUNCTION__);
    DEBUG_PRINTF("    I2S%u: DataFormat: %u\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.DataFormat);
    DEBUG_PRINTF("    I2S%u: CPOL: %u\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.CPOL);
    DEBUG_PRINTF("    I2S%u: (dbits, fbits): (%u, %u)\r\n", obj->i2s.module + 1,
    	(unsigned int)dbits, (unsigned int)fbits);
    DEBUG_PRINTF("    I2S%u: Polarity: %u\r\n", obj->i2s.module + 1,
    	(unsigned int)polarity);

    init_i2s(obj);
}

void i2s_set_mode(i2s_t *obj, i2s_mode_t mode) {
    uint8_t dma_direction;
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];

    handle->Init.Mode = i2s_get_mode(mode, &dma_direction);

    // Save primary DMA direction
    obj->dma.dma_direction = dma_direction;

    DEBUG_PRINTF("--> %s\r\n", __FUNCTION__);
    DEBUG_PRINTF("    I2S%u: Mode: %u (%u)\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.Mode, (unsigned int)mode);

    init_i2s(obj);
}

void i2s_set_protocol(i2s_t *obj, i2s_bitorder_t protocol) {
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];

    switch (protocol)
    {
    	case PHILIPS:
			handle->Init.Standard = I2S_STANDARD_PHILIPS;
			break;
	    case MSB:
			handle->Init.Standard = I2S_STANDARD_MSB;
			break;
		case LSB:
			handle->Init.Standard = I2S_STANDARD_LSB;
			break;
	    case PCM_SHORT:
			handle->Init.Standard = I2S_STANDARD_PCM_SHORT;
			break;
	    case PCM_LONG:
	    default:
			handle->Init.Standard = I2S_STANDARD_PCM_LONG;
			break;
    }

    DEBUG_PRINTF("--> %s\r\n", __FUNCTION__);
    DEBUG_PRINTF("    I2S%u: Standard: %u\r\n", obj->i2s.module + 1,
		(unsigned int)handle->Init.Standard);

    init_i2s(obj);
}

void i2s_audio_frequency(i2s_t *obj, uint32_t hz) {
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];

    if (IS_I2S_AUDIO_FREQ(hz) && (hz != I2S_AUDIOFREQ_DEFAULT)) {
    	handle->Init.AudioFreq = hz;
    }
    else if (hz < I2S_AUDIOFREQ_8K) {
		handle->Init.AudioFreq = I2S_AUDIOFREQ_8K;
    }
    else {
		handle->Init.AudioFreq = I2S_AUDIOFREQ_192K; 
    }

	DEBUG_PRINTF("--> %s\r\n", __FUNCTION__);
    DEBUG_PRINTF("    I2S%u: AudioFreq: %u\r\n", obj->i2s.module + 1,
    	(unsigned int)handle->Init.AudioFreq);

    init_i2s(obj);
}

uint8_t i2s_get_module(i2s_t *obj) {
    return obj->i2s.module;
}

static void i2s_start_asynch_transfer(i2s_t *obj, transfer_type_t transfer_type, void *tx, void *rx, int length) {
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];
    obj->i2s.transfer_type = transfer_type;

    // the HAL expects number of transfers instead of number of bytes
    int words;
    switch(handle->Init.DataFormat) {
	    case I2S_DATAFORMAT_16B:
	    case I2S_DATAFORMAT_16B_EXTENDED:
			words = length / 2;
			if(words > 0xFFFC) words = 0xFFFC; // truncate in order to respect max DMA length
			break;
	    case I2S_DATAFORMAT_24B:
	    case I2S_DATAFORMAT_32B:
	    default:
			words = length / 4;
			if(words > 0x7FFC) words = 0x7FFC; // truncate in order to respect max DMA length
			break;
    }

    // enable the right hal transfer
    int rc = 0;
    switch(transfer_type) {
	    case I2S_TRANSFER_TYPE_TXRX:
			// enable the interrupts
			NVIC_EnableIRQ(obj->dma.dma[DMA_TX]->dma_stream_irq);
			NVIC_EnableIRQ(obj->dma.dma[DMA_RX]->dma_stream_irq);
			// trigger DMA transfers
			rc = HAL_I2SEx_TransmitReceive_DMA(handle, (uint16_t*)tx, (uint16_t*)rx, (uint16_t)words);
			break;
	    case I2S_TRANSFER_TYPE_TX:
			// enable the interrupt
			NVIC_EnableIRQ(obj->dma.dma[DMA_TX]->dma_stream_irq);
			// trigger DMA transfer
			rc = HAL_I2S_Transmit_DMA(handle, (uint16_t*)tx, (uint16_t)words);
			break;
	    case I2S_TRANSFER_TYPE_RX:
			// enable the interrupt
			NVIC_EnableIRQ(obj->dma.dma[DMA_RX]->dma_stream_irq);
			// trigger DMA transfer
			rc = HAL_I2S_Receive_DMA(handle, (uint16_t*)rx, (uint16_t)words);
			break;
    }

    if (rc) {
		DEBUG_PRINTF("    I2S%u: RC: %d\r\n", obj->i2s.module + 1, rc);
    }

    return;
}

// asynchronous API
void i2s_transfer(i2s_t *obj,
		  void *tx, int tx_length,
		  void *rx, int rx_length,
		  bool circular, i2s_dma_prio_t prio,
		  uint32_t handler_tx, uint32_t handler_rx, uint32_t event) {
    // check which use-case we have
    bool use_tx = (tx != NULL && tx_length > 0);
    bool use_rx = (rx != NULL && rx_length > 0);

    // Init DMAs
    dma_i2s_init(obj, &use_tx, &use_rx, circular, prio);

    // don't do anything, if the buffers aren't valid
    if (!use_tx && !use_rx)
	return;

    // copy the buffers to the I2S object
    obj->tx_buff.buffer = tx;
    obj->tx_buff.length = tx_length;
    obj->tx_buff.pos = 0;
    obj->tx_buff.width = 16;

    obj->rx_buff.buffer = rx;
    obj->rx_buff.length = rx_length;
    obj->rx_buff.pos = 0;
    obj->rx_buff.width = obj->tx_buff.width;

    obj->i2s.event = event;

    DEBUG_PRINTF("    I2S%u: Transfer: %u, %u\r\n", obj->i2s.module + 1, tx_length, rx_length);

    // register the thunking handler
    if (use_tx) {
		NVIC_SetVector(obj->dma.dma[DMA_TX]->dma_stream_irq, handler_tx);
    }
    if (use_rx) {
		NVIC_SetVector(obj->dma.dma[DMA_RX]->dma_stream_irq, handler_rx);
    }

    // enable the right hal transfer
    if (use_tx && use_rx) {
		int size = (tx_length < rx_length)? tx_length : rx_length;
		i2s_start_asynch_transfer(obj, I2S_TRANSFER_TYPE_TXRX, tx, rx, size);
    } else if (use_tx) {
		i2s_start_asynch_transfer(obj, I2S_TRANSFER_TYPE_TX, tx, NULL, tx_length);
    } else if (use_rx) {
		i2s_start_asynch_transfer(obj, I2S_TRANSFER_TYPE_RX, NULL, rx, rx_length);
    }
}

uint32_t i2s_irq_handler_asynch(i2s_t *obj, uint8_t direction) {
    direction = (direction == I2S_TX_EVENT) ? DMA_TX : DMA_RX;

    // use the right instance
    I2S_HandleTypeDef *i2s_handle = &I2sHandle[obj->i2s.module];
    DMA_HandleTypeDef *dma_handle = (direction == DMA_TX) ? i2s_handle->hdmatx : i2s_handle->hdmarx;

    MBED_ASSERT(dma_handle != NULL);

    int event = 0;

    // call the Cube handler, this will update the handle
    HAL_DMA_IRQHandler(dma_handle);

    switch(HAL_I2S_GetState(i2s_handle))
    {
	    case HAL_I2S_STATE_READY: {
			// adjust buffer positions (betzw - TODO: to be checked for DMA transfers!!!)
			int tx_size = (i2s_handle->TxXferSize - i2s_handle->TxXferCount);
			int rx_size = (i2s_handle->RxXferSize - i2s_handle->RxXferCount);

			// take data format into consideration
			switch(i2s_handle->Init.DataFormat)
			{
				case I2S_DATAFORMAT_16B:
				case I2S_DATAFORMAT_16B_EXTENDED:
				    tx_size *= 2;
				    rx_size *= 2;
				    break;
				case I2S_DATAFORMAT_24B:
				case I2S_DATAFORMAT_32B:
				default:
				    tx_size *= 4;
				    rx_size *= 4;
				    break;
			}

			// adjust buffer positions
			if (obj->i2s.transfer_type != I2S_TRANSFER_TYPE_RX) {
			    obj->tx_buff.pos += tx_size;
			}
			if (obj->i2s.transfer_type != I2S_TRANSFER_TYPE_TX) {
			    obj->rx_buff.pos += rx_size;
			}

			if (i2s_handle->TxXferCount > 0) {
			    DEBUG_PRINTF("    I2S%u: TxXferCount: %u\r\n", obj->i2s.module + 1, i2s_handle->TxXferCount);
			}
			if (i2s_handle->RxXferCount > 0) {
			    DEBUG_PRINTF("    I2S%u: RxXferCount: %u\r\n", obj->i2s.module + 1, i2s_handle->RxXferCount);
			}
	    }
    	/* no break */

	    case HAL_I2S_STATE_BUSY_TX:
	    case HAL_I2S_STATE_BUSY_RX:
	    case HAL_I2S_STATE_BUSY_TX_RX:
			{
				int error = HAL_I2S_GetError(i2s_handle);

				if (error != HAL_I2S_ERROR_NONE) {
					// something went wrong and the transfer has definitely completed
					event = ((direction == DMA_TX) ? I2S_EVENT_TX_ERROR : I2S_EVENT_RX_ERROR) | I2S_EVENT_INTERNAL_TRANSFER_COMPLETE;

					if (error & HAL_I2S_ERROR_OVR) {
						// buffer overrun
						event |= I2S_EVENT_RX_OVERFLOW;
					}

					if (error & HAL_I2S_ERROR_UDR) {
						// buffer underrun
						event |= I2S_EVENT_TX_UNDERRUN;
					}

					// cleanup DMA (after error)
					dma_i2s_free(obj, direction);
				} else
				{ // no error detected
					HAL_DMA_StateTypeDef dma_state = HAL_DMA_GetState(dma_handle);

					switch(dma_state)
					{
						case HAL_DMA_STATE_READY_HALF_MEM0:
						case HAL_DMA_STATE_READY_HALF_MEM1:
							event = ((direction == DMA_TX) ? I2S_EVENT_TX_HALF_COMPLETE : I2S_EVENT_RX_HALF_COMPLETE);
							break;
						case HAL_DMA_STATE_READY_MEM0:
						case HAL_DMA_STATE_READY_MEM1:
							event = ((direction == DMA_TX) ? I2S_EVENT_TX_COMPLETE : I2S_EVENT_RX_COMPLETE);
							if(dma_handle->Init.Mode != DMA_CIRCULAR)
							{
								if (!i2s_active(obj))
								{ // Check for full-duplex transfer complete!
									event |= I2S_EVENT_INTERNAL_TRANSFER_COMPLETE;
								}

								// cleanup DMA (because we are done)
								dma_i2s_free(obj, direction);
							}
							break;
						default:
							printf("betzw(%s, %d): dma_state=0x%x\r\n", __func__, __LINE__, (int)dma_state);
							MBED_ASSERT(0);
							break;
					}
				}
	    	}
			break;
	    default:
			// nothing to do?!?
			break;
    }

    if (event) DEBUG_PRINTF("    I2S%u: Event: 0x%x\r\n", obj->i2s.module + 1, event);

    return (event & (obj->i2s.event | I2S_EVENT_INTERNAL_TRANSFER_COMPLETE));
}

uint8_t i2s_active(i2s_t *obj) {
    I2S_HandleTypeDef *handle = &I2sHandle[obj->i2s.module];
    HAL_I2S_StateTypeDef state = HAL_I2S_GetState(handle);

    switch(state){
	    case HAL_I2S_STATE_RESET:
	    case HAL_I2S_STATE_READY:
	    case HAL_I2S_STATE_ERROR:
			return 0;
	    default:
			return -1;
    }
}

void i2s_abort_asynch(i2s_t *obj) {
    I2S_HandleTypeDef *i2s_handle = &I2sHandle[obj->i2s.module];

    // Stop transfer
    HAL_I2S_DMAStop(i2s_handle);

    if(obj->dma.dma[DMA_TX] != NULL) {
		DMA_HandleTypeDef *dma_handle_tx = &DMaHandles[obj->i2s.module][DMA_TX];

		// disable interrupt & free resource
		dma_i2s_free(obj, DMA_TX);
	 
		//clean up
		__HAL_DMA_DISABLE(dma_handle_tx);
		HAL_DMA_DeInit(dma_handle_tx);
		HAL_DMA_Init(dma_handle_tx);
		__HAL_DMA_ENABLE(dma_handle_tx);
    }
    if(obj->dma.dma[DMA_RX] != NULL) {
		DMA_HandleTypeDef *dma_handle_rx = &DMaHandles[obj->i2s.module][DMA_RX];

		// disable interrupt & free resource
		dma_i2s_free(obj, DMA_RX);

		//clean up
		__HAL_DMA_DISABLE(dma_handle_rx);
		HAL_DMA_DeInit(dma_handle_rx);
		HAL_DMA_Init(dma_handle_rx);
		__HAL_DMA_ENABLE(dma_handle_rx);
    }

    // clean-up I2S
    __HAL_I2S_DISABLE(i2s_handle);
    HAL_I2S_DeInit(i2s_handle);
    HAL_I2S_Init(i2s_handle);
    __HAL_I2S_ENABLE(i2s_handle);
}

#endif