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Describes the interface to the EDMA manager.
The edma user interface library wraps file system calls to an associated kernel module (edmak.ko), which needs to be loaded in order for calls to to this library to succeed.
To install edmak.ko, enter % insmod edmak.ko on a Linux command line.
EDMA channels are allocated (requested) from within the edmak kernel driver through the EDMA_getResource() API. This request is granted by way of the kernel's request_dma() functionality (davinci_request_dma() for the DM365), so it will work in conjuntion with independent kernel DMA usage without conflict or custom kernel configuration.
EDMA registers can be mapped to a process's address by way of the API EDMA_mapBaseAddress(). The EDMA registers are memory-mapped into the calling process' user address space to allow the application to directly access the EDMA registers.
Resource allocation is tracked at the process level by way of a 'process registration' list. The initial allocator of a resource (the process that calls EDMA_getResource()) is automatically added to the registration list, and further processes can become registered for the same resource by way of the EDMA_registerResource() API (and unregister with the EDMA_unregister() API). This registration list for each resource (logical channel) allows for resource ownership tracking and cleanup on a per-process basis, so that when a process exits or dies without having explicitly freed/unregistered its resources, they get automatically unregistered (and freed when no more registered processes exist). Only when the last registered process frees a resource (either explictily, or by auto-cleanup) does a resource actually get freed back to the kernel.
Since the EDMA interface library doesn't use the GT tracing facility, there is one configuration option available for the EDMA module to control whether the debug or release interface library is used for building the application. This config parameter is named 'debug' and is of type bool, and the default value is 'false'.
The following line is an example of enabling usage of the debug interface library: var edma = xdc.useModule('ti.sdo.linuxutils.edma.EDMA'); edma.debug = true; This will enable "EDMA Debug" statements to be printed to stdout.
Go to the source code of this file.
Data Structures | |
| struct | EDMA_requestDmaParams |
| EDMAK ioctl input/output parameters. More... | |
| struct | EDMA_releaseDmaParams |
| EDMAK ioctl input parameters. More... | |
Defines | |
| #define | EDMA_VERSION 0x02000000U |
| #define | EDMA_TCCANY 1001 |
| Values for dev_id parameter of EDMA_getResource() | |
| #define | EDMA_TCCSYMM 1005 |
| #define | EDMA_PARAMANY 1006 |
| #define | EDMA_PARAMFIXEDEXACT 1007 |
| #define | EDMA_PARAMFIXEDNOTEXACT 1008 |
| #define | EDMA_EDMAANY 1003 |
| #define | EDMA_QDMAANY 1004 |
| #define | EDMA_QDMA0 512 |
| #define | EDMA_QDMA1 EDMA_QDMA(1) |
| #define | EDMA_QDMA2 EDMA_QDMA(2) |
| #define | EDMA_QDMA3 EDMA_QDMA(3) |
| #define | EDMA_QDMA4 EDMA_QDMA(4) |
| #define | EDMA_QDMA5 EDMA_QDMA(5) |
| #define | EDMA_QDMA6 EDMA_QDMA(6) |
| #define | EDMA_QDMA7 EDMA_QDMA(7) |
| #define | EDMA_QDMA(n) (EDMA_QDMA0 + (n)) |
| macro used to translate from a QDMA channel # to the numerical range used by EDMA_getResource() & EDMA_freeResource() for representing a QDMA channel. | |
| #define | EDMA_QDMA2NUM(qdma) (qdma - EDMA_QDMA0) |
| macro to translate from EDMA_QDMA0 -> EDMA_QDMA7 namespace to actual QDMA number 0 -> 7. | |
| #define | EDMA_IOCMAGIC 0x0000fd00 |
| #define | EDMA_IOCCMDMASK 0x000000ff |
Typedefs | |
| typedef enum EDMA_Status | EDMA_Status |
| Status codes for EDMA API return values. | |
Enumerations | |
| enum | EDMA_commmands { EDMA_IOCREQUESTDMA = 1, EDMA_IOCRELEASEDMA, EDMA_IOCGETVERSION, EDMA_IOCGETBASEPHYSADDR, EDMA_IOCREGUSER } |
EDMAK ioctl() commands. More... | |
| enum | EDMA_Status { EDMA_OK = 0, EDMA_EFAIL, EDMA_ENOCHANNEL, EDMA_ENOINIT } |
Status codes for EDMA API return values. More... | |
Functions | |
| int | EDMA_init (void) |
| EDMA initialization API. | |
| int | EDMA_exit (void) |
| EDMA finalization API. | |
| EDMA_Status | EDMA_mapBaseAddress (void **pvirtAddr) |
| Returns user space virtual address of EDMA base registers. | |
| EDMA_Status | EDMA_getResource (int devId, int *tcc, int *channel, int *param, int nParams) |
| Returns available logical channels. | |
| EDMA_Status | EDMA_freeResource (int lch, int nParams) |
| Frees previously requested logical channel. | |
| int | EDMA_getVersion (void) |
| Retrieve version from EDMA driver. | |
| EDMA_Status | EDMA_registerResource (int lch) |
| Registers calling process as a user of lch. | |
| EDMA_Status | EDMA_unregister (int lch, int nParams) |
| Unregisters calling process as a user of lch. | |
