drivers/mtd/devices/ms02-nv.h

   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 };