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1==================================2SD and MMC Block Device Attributes3==================================4 5These attributes are defined for the block devices associated with the6SD 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 Attributes15============================16 17All attributes are read-only.18 19 ====================== ===============================================20 cid Card Identification Register21 csd Card Specific Data Register22 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 size35 preferred_erase_size Preferred erase size36 raw_rpmb_size_mult RPMB partition size37 rel_sectors Reliable write sector count38 ocr Operation Conditions Register39 dsr Driver Stage Register40 cmdq_en Command Queue enabled:41 42 1 => enabled, 0 => not enabled43 ====================== ===============================================44 45Note on Erase Size and Preferred Erase Size:46 47 "erase_size" is the minimum size, in bytes, of an erase48 operation. For MMC, "erase_size" is the erase group size49 reported by the card. Note that "erase_size" does not apply50 to trim or secure trim operations where the minimum size is51 always one 512 byte sector. For SD, "erase_size" is 51252 if the card is block-addressed, 0 otherwise.53 54 SD/MMC cards can erase an arbitrarily large area up to and55 including the whole card. When erasing a large area it may56 be desirable to do it in smaller chunks for three reasons:57 58 1. A single erase command will make all other I/O on59 the card wait. This is not a problem if the whole card60 is being erased, but erasing one partition will make61 I/O for another partition on the same card wait for the62 duration of the erase - which could be a several63 minutes.64 2. To be able to inform the user of erase progress.65 3. The erase timeout becomes too large to be very66 useful. Because the erase timeout contains a margin67 which is multiplied by the size of the erase area,68 the value can end up being several minutes for large69 areas.70 71 "erase_size" is not the most efficient unit to erase72 (especially for SD where it is just one sector),73 hence "preferred_erase_size" provides a good chunk74 size for erasing large areas.75 76 For MMC, "preferred_erase_size" is the high-capacity77 erase size if a card specifies one, otherwise it is78 based on the capacity of the card.79 80 For SD, "preferred_erase_size" is the allocation unit81 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_mult92