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