1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | /* |
3 | * Copyright (c) 2001, 2003 Maciej W. Rozycki |
4 | * |
5 | * DEC MS02-NV (54-20948-01) battery backed-up NVRAM module for |
6 | * DECstation/DECsystem 5000/2x0 and DECsystem 5900 and 5900/260 |
7 | * systems. |
8 | */ |
9 | |
10 | #include <linux/ioport.h> |
11 | #include <linux/mtd/mtd.h> |
12 | |
13 | /* |
14 | * Addresses are decoded as follows: |
15 | * |
16 | * 0x000000 - 0x3fffff SRAM |
17 | * 0x400000 - 0x7fffff CSR |
18 | * |
19 | * Within the SRAM area the following ranges are forced by the system |
20 | * firmware: |
21 | * |
22 | * 0x000000 - 0x0003ff diagnostic area, destroyed upon a reboot |
23 | * 0x000400 - ENDofRAM storage area, available to operating systems |
24 | * |
25 | * but we can't really use the available area right from 0x000400 as |
26 | * the first word is used by the firmware as a status flag passed |
27 | * from an operating system. If anything but the valid data magic |
28 | * ID value is found, the firmware considers the SRAM clean, i.e. |
29 | * containing no valid data, and disables the battery resulting in |
30 | * data being erased as soon as power is switched off. So the choice |
31 | * for the start address of the user-available is 0x001000 which is |
32 | * nicely page aligned. The area between 0x000404 and 0x000fff may |
33 | * be used by the driver for own needs. |
34 | * |
35 | * The diagnostic area defines two status words to be read by an |
36 | * operating system, a magic ID to distinguish a MS02-NV board from |
37 | * anything else and a status information providing results of tests |
38 | * as well as the size of SRAM available, which can be 1MiB or 2MiB |
39 | * (that's what the firmware handles; no idea if 2MiB modules ever |
40 | * existed). |
41 | * |
42 | * The firmware only handles the MS02-NV board if installed in the |
43 | * last (15th) slot, so for any other location the status information |
44 | * stored in the SRAM cannot be relied upon. But from the hardware |
45 | * point of view there is no problem using up to 14 such boards in a |
46 | * system -- only the 1st slot needs to be filled with a DRAM module. |
47 | * The MS02-NV board is ECC-protected, like other MS02 memory boards. |
48 | * |
49 | * The state of the battery as provided by the CSR is reflected on |
50 | * the two onboard LEDs. When facing the battery side of the board, |
51 | * with the LEDs at the top left and the battery at the bottom right |
52 | * (i.e. looking from the back side of the system box), their meaning |
53 | * is as follows (the system has to be powered on): |
54 | * |
55 | * left LED battery disable status: lit = enabled |
56 | * right LED battery condition status: lit = OK |
57 | */ |
58 | |
59 | /* MS02-NV iomem register offsets. */ |
60 | #define MS02NV_CSR 0x400000 /* control & status register */ |
61 | |
62 | /* MS02-NV CSR status bits. */ |
63 | #define MS02NV_CSR_BATT_OK 0x01 /* battery OK */ |
64 | #define MS02NV_CSR_BATT_OFF 0x02 /* battery disabled */ |
65 | |
66 | |
67 | /* MS02-NV memory offsets. */ |
68 | #define MS02NV_DIAG 0x0003f8 /* diagnostic status */ |
69 | #define MS02NV_MAGIC 0x0003fc /* MS02-NV magic ID */ |
70 | #define MS02NV_VALID 0x000400 /* valid data magic ID */ |
71 | #define MS02NV_RAM 0x001000 /* user-exposed RAM start */ |
72 | |
73 | /* MS02-NV diagnostic status bits. */ |
74 | #define MS02NV_DIAG_TEST 0x01 /* SRAM test done (?) */ |
75 | #define MS02NV_DIAG_RO 0x02 /* SRAM r/o test done */ |
76 | #define MS02NV_DIAG_RW 0x04 /* SRAM r/w test done */ |
77 | #define MS02NV_DIAG_FAIL 0x08 /* SRAM test failed */ |
78 | #define MS02NV_DIAG_SIZE_MASK 0xf0 /* SRAM size mask */ |
79 | #define MS02NV_DIAG_SIZE_SHIFT 0x10 /* SRAM size shift (left) */ |
80 | |
81 | /* MS02-NV general constants. */ |
82 | #define MS02NV_ID 0x03021966 /* MS02-NV magic ID value */ |
83 | #define MS02NV_VALID_ID 0xbd100248 /* valid data magic ID value */ |
84 | #define MS02NV_SLOT_SIZE 0x800000 /* size of the address space |
85 | decoded by the module */ |
86 | |
87 | |
88 | typedef volatile u32 ms02nv_uint; |
89 | |
90 | struct ms02nv_private { |
91 | struct mtd_info *next; |
92 | struct { |
93 | struct resource *module; |
94 | struct resource *diag_ram; |
95 | struct resource *user_ram; |
96 | struct resource *csr; |
97 | } resource; |
98 | u_char *addr; |
99 | size_t size; |
100 | u_char *uaddr; |
101 | }; |
102 | |