FatFs: SD_ioctl doesn't support the CTRL_TRIM command

[Steve Neves]

I want to enable trim support that is baked into FatFs, however the SD_ioctl function provided by ST does not include many of the FatFs commands, only what is listed below. Has anyone implemented this before? I plan on doing data logging on a micro SD card and want to ensure the longest life possible. Thanks.

/* USER CODE BEGIN beforeIoctlSection */
/* can be used to modify previous code / undefine following code / add new code */
/* USER CODE END beforeIoctlSection */
/**
 * @brief I/O control operation
 * @param lun : not used
 * @param cmd: Control code
 * @param *buff: Buffer to send/receive control data
 * @retval DRESULT: Operation result
 */
#if _USE_IOCTL == 1
DRESULT SD_ioctl(BYTE lun, BYTE cmd, void *buff)
{
 DRESULT res = RES_ERROR;
 BSP_SD_CardInfo CardInfo;
 
 if (Stat & STA_NOINIT) return RES_NOTRDY;
 
 switch (cmd)
 {
 /* Make sure that no pending write process */
 case CTRL_SYNC :
 res = RES_OK;
 break;
 
 /* Get number of sectors on the disk (DWORD) */
 case GET_SECTOR_COUNT :
 BSP_SD_GetCardInfo(&CardInfo);
 *(DWORD*)buff = CardInfo.LogBlockNbr;
 res = RES_OK;
 break;
 
 /* Get R/W sector size (WORD) */
 case GET_SECTOR_SIZE :
 BSP_SD_GetCardInfo(&CardInfo);
 *(WORD*)buff = CardInfo.LogBlockSize;
 res = RES_OK;
 break;
 
 /* Get erase block size in unit of sector (DWORD) */
 case GET_BLOCK_SIZE :
 BSP_SD_GetCardInfo(&CardInfo);
 *(DWORD*)buff = CardInfo.LogBlockSize / SD_DEFAULT_BLOCK_SIZE;
 res = RES_OK;
 break;
 default:
 res = RES_PARERR;
 }
 
 return res;
}
#endif /* _USE_IOCTL == 1 */

[jaakjensen]

I think you can just add another case called "CTRL_TRIM" and then instruct the BSP to erase whatever blocks are requested. You can call HAL_SD_Erase(&hsd_sdmmc, st, ed) instead of BSP_SD_Erase();

The return value of this function when the command CTRL_TRIM is used is not checked by ff.c / ff.h so I don't believe error checking is required.

 /* Tell the disk to erase the requested sectors */
 case CTRL_TRIM :
	 tmp = buff;
	 st = *tmp;
	 ed = *(tmp+1);
	 BSP_SD_Erase(0, st, ed-st);
	 res = RES_OK;
	 break;