1================================== 2SD and MMC Block Device Attributes 3================================== 4 5These attributes are defined for the block devices associated with the 6SD or MMC device. 7 8The following attributes are read/write. 9 10 ======== =============================================== 11 force_ro Enforce read-only access even if write protect switch is off. 12 ======== =============================================== 13 14SD and MMC Device Attributes 15============================ 16 17All attributes are read-only. 18 19 ====================== =============================================== 20 cid Card Identification Register 21 csd Card Specific Data Register 22 scr SD Card Configuration Register (SD only) 23 date Manufacturing Date (from CID Register) 24 fwrev Firmware/Product Revision (from CID Register) 25 (SD and MMCv1 only) 26 hwrev Hardware/Product Revision (from CID Register) 27 (SD and MMCv1 only) 28 manfid Manufacturer ID (from CID Register) 29 name Product Name (from CID Register) 30 oemid OEM/Application ID (from CID Register) 31 prv Product Revision (from CID Register) 32 (SD and MMCv4 only) 33 serial Product Serial Number (from CID Register) 34 erase_size Erase group size 35 preferred_erase_size Preferred erase size 36 raw_rpmb_size_mult RPMB partition size 37 rel_sectors Reliable write sector count 38 ocr Operation Conditions Register 39 dsr Driver Stage Register 40 cmdq_en Command Queue enabled: 41 42 1 => enabled, 0 => not enabled 43 ====================== =============================================== 44 45Note on Erase Size and Preferred Erase Size: 46 47 "erase_size" is the minimum size, in bytes, of an erase 48 operation. For MMC, "erase_size" is the erase group size 49 reported by the card. Note that "erase_size" does not apply 50 to trim or secure trim operations where the minimum size is 51 always one 512 byte sector. For SD, "erase_size" is 512 52 if the card is block-addressed, 0 otherwise. 53 54 SD/MMC cards can erase an arbitrarily large area up to and 55 including the whole card. When erasing a large area it may 56 be desirable to do it in smaller chunks for three reasons: 57 58 1. A single erase command will make all other I/O on 59 the card wait. This is not a problem if the whole card 60 is being erased, but erasing one partition will make 61 I/O for another partition on the same card wait for the 62 duration of the erase - which could be a several 63 minutes. 64 2. To be able to inform the user of erase progress. 65 3. The erase timeout becomes too large to be very 66 useful. Because the erase timeout contains a margin 67 which is multiplied by the size of the erase area, 68 the value can end up being several minutes for large 69 areas. 70 71 "erase_size" is not the most efficient unit to erase 72 (especially for SD where it is just one sector), 73 hence "preferred_erase_size" provides a good chunk 74 size for erasing large areas. 75 76 For MMC, "preferred_erase_size" is the high-capacity 77 erase size if a card specifies one, otherwise it is 78 based on the capacity of the card. 79 80 For SD, "preferred_erase_size" is the allocation unit 81 size specified by the card. 82 83 "preferred_erase_size" is in bytes. 84 85Note on raw_rpmb_size_mult: 86 87 "raw_rpmb_size_mult" is a multiple of 128kB block. 88 89 RPMB size in byte is calculated by using the following equation: 90 91 RPMB partition size = 128kB x raw_rpmb_size_mult 92