| SD and MMC Block Device Attributes | |
| ================================== | |
| These attributes are defined for the block devices associated with the | |
| SD or MMC device. | |
| The following attributes are read/write. | |
| force_ro Enforce read-only access even if write protect switch is off. | |
| SD and MMC Device Attributes | |
| ============================ | |
| All attributes are read-only. | |
| cid Card Identification Register | |
| csd Card Specific Data Register | |
| scr SD Card Configuration Register (SD only) | |
| date Manufacturing Date (from CID Register) | |
| fwrev Firmware/Product Revision (from CID Register) (SD and MMCv1 only) | |
| hwrev Hardware/Product Revision (from CID Register) (SD and MMCv1 only) | |
| manfid Manufacturer ID (from CID Register) | |
| name Product Name (from CID Register) | |
| oemid OEM/Application ID (from CID Register) | |
| prv Product Revision (from CID Register) (SD and MMCv4 only) | |
| serial Product Serial Number (from CID Register) | |
| erase_size Erase group size | |
| preferred_erase_size Preferred erase size | |
| raw_rpmb_size_mult RPMB partition size | |
| rel_sectors Reliable write sector count | |
| ocr Operation Conditions Register | |
| dsr Driver Stage Register | |
| cmdq_en Command Queue enabled: 1 => enabled, 0 => not enabled | |
| Note on Erase Size and Preferred Erase Size: | |
| "erase_size" is the minimum size, in bytes, of an erase | |
| operation. For MMC, "erase_size" is the erase group size | |
| reported by the card. Note that "erase_size" does not apply | |
| to trim or secure trim operations where the minimum size is | |
| always one 512 byte sector. For SD, "erase_size" is 512 | |
| if the card is block-addressed, 0 otherwise. | |
| SD/MMC cards can erase an arbitrarily large area up to and | |
| including the whole card. When erasing a large area it may | |
| be desirable to do it in smaller chunks for three reasons: | |
| 1. A single erase command will make all other I/O on | |
| the card wait. This is not a problem if the whole card | |
| is being erased, but erasing one partition will make | |
| I/O for another partition on the same card wait for the | |
| duration of the erase - which could be a several | |
| minutes. | |
| 2. To be able to inform the user of erase progress. | |
| 3. The erase timeout becomes too large to be very | |
| useful. Because the erase timeout contains a margin | |
| which is multiplied by the size of the erase area, | |
| the value can end up being several minutes for large | |
| areas. | |
| "erase_size" is not the most efficient unit to erase | |
| (especially for SD where it is just one sector), | |
| hence "preferred_erase_size" provides a good chunk | |
| size for erasing large areas. | |
| For MMC, "preferred_erase_size" is the high-capacity | |
| erase size if a card specifies one, otherwise it is | |
| based on the capacity of the card. | |
| For SD, "preferred_erase_size" is the allocation unit | |
| size specified by the card. | |
| "preferred_erase_size" is in bytes. | |
| Note on raw_rpmb_size_mult: | |
| "raw_rpmb_size_mult" is a multiple of 128kB block. | |
| RPMB size in byte is calculated by using the following equation: | |
| RPMB partition size = 128kB x raw_rpmb_size_mult |