1.1.2.4.1 DRV_AK4954_Open Function
DRV_HANDLE DRV_AK4954_Open ( const SYS_MODULE_INDEX drvIndex, const DRV_IO_INTENT ioIntent )
Summary
Opens the specified AK4954 driver instance and returns a handle to it.
Description
This routine opens the specified AK4954 driver instance and provides a handle that must be provided to all other client-level operations to identify the caller and the instance of the driver. The ioIntent parameter defines how the client interacts with this driver instance.
The DRV_IO_INTENT_BLOCKING and DRV_IO_INTENT_NONBLOCKING ioIntent options are not relevant to this driver. All the data transfer functions of this driver are non blocking.
AK4954 can be opened with DRV_IO_INTENT_WRITE, or DRV_IO_INTENT_READ or DRV_IO_INTENT_WRITEREAD io_intent option. This decides whether the driver is used for headphone output, or microphone input or both modes simultaneously.
Specifying a DRV_IO_INTENT_EXCLUSIVE will cause the driver to provide exclusive access to this client. The driver cannot be opened by any other client.
Preconditions
Function DRV_AK4954_Initialize must have been called before calling this function.
Parameters
| Parameters | Description |
|---|---|
| drvIndex | Identifier for the object instance to be opened |
| ioIntent | Zero or more of the values from the enumeration DRV_IO_INTENT "ORed" together to indicate the intended use of the driver. See function description for details. |
Returns
If successful, the routine returns a valid open-instance handle (a number identifying both the caller and the module instance).
If an error occurs, the return value is DRV_HANDLE_INVALID. Error can occur
if the number of client objects allocated via DRV_AK4954_CLIENTS_NUMBER is insufficient.
if the client is trying to open the driver but driver has been opened exclusively by another client.
if the driver hardware instance being opened is not initialized or is invalid.
if the ioIntent options passed are not relevant to this driver.
Remarks
The handle returned is valid until the DRV_AK4954_Close routine is called. This routine will NEVER block waiting for hardware.If the requested intent flags are not supported, the routine will return DRV_HANDLE_INVALID. This function is thread safe in a RTOS application. It should not be called in an ISR.
Example
DRV_HANDLE handle; handle = DRV_AK4954_Open(DRV_AK4954_INDEX_0, DRV_IO_INTENT_WRITEREAD | DRV_IO_INTENT_EXCLUSIVE); if (DRV_HANDLE_INVALID == handle) {
_\/\/ Unable to open the driver_
_\/\/ May be the driver is not initialized or the initialization_ _\/\/ is not complete._
}C
DRV_HANDLE DRV_AK4954_Open(const SYS_MODULE_INDEX iDriver, const DRV_IO_INTENT ioIntent);