DCMD_SDMMC_GEN_CMD
Send a general command to the device
Synopsis:
#include <hw/dcmd_sim_sdmmc.h>
#define DCMD_SDMMC_GEN_CMD __DIOTF(_DCMD_CAM, _SIM_SDMMC + 12, struct _sdmmc_gen_cmd)
Arguments to devctl():
| Argument | Value |
|---|---|
| filedes | A file descriptor that you obtained by opening the device |
| dcmd | DCMD_SDMMC_GEN_CMD |
| dev_data_ptr | A pointer to an SDMMC_GEN_CMD that's followed by a buffer |
| n_bytes | sizeof(SDMMC_GEN_CMD) plus the size of the buffer |
| dev_info_ptr | NULL |
Description:
This is a general command whose meaning, expected input data, and output data are defined by the vendor. For instance, this command could extract vendor-specific device health information, or configure a proprietary mechanism such as refresh.
The SDMMC_GEN_CMD structure is defined as follows:
typedef struct _sdmmc_gen_cmd {
uint32_t arg;
uint16_t flags;
uint16_t blklen;
/* uint8_t data[0]; variable-length data */
} SDMMC_GEN_CMD;
The members include:
- arg
- Additional command arguments, as defined by the vendor.
- flags
- Flags indicating the data direction and whether there is a chained command.
On input, this field must contain either SDMMC_GENCMD_READ for reading or SDMMC_GENCMD_WRITE for writing, and may also contain SDMMC_GENCMD_NEXT to indicate there is a chained command.
The SDMMC_GENCMD_DIR mask can be used to extract the data direction bit.
- blklen
- The length of the data field that follows this structure.
Input:
Fill in the arg, flags, and blklen members. Any data that is to be sent to the device must be written into the data field that follows the command structure. The format of the data is vendor-specific.
Output:
The buffer that data points to is filled with the response, and blklen is set to its length. The contents and format of the data are vendor-specific.
See also:
devctl() in the QNX OS C Library Reference