mtd/devices/ms02-nv.h

0001 /* SPDX-License-Identifier: GPL-2.0-or-later */
0002 /*
0003  *  Copyright (c) 2001, 2003  Maciej W. Rozycki
0004  *
0005  *  DEC MS02-NV (54-20948-01) battery backed-up NVRAM module for
0006  *  DECstation/DECsystem 5000/2x0 and DECsystem 5900 and 5900/260
0007  *  systems.
0008  */
0009
0010 #include <linux/ioport.h>
0011 #include <linux/mtd/mtd.h>
0012
0013 /*
0014  * Addresses are decoded as follows:
0015  *
0016  * 0x000000 - 0x3fffff  SRAM
0017  * 0x400000 - 0x7fffff  CSR
0018  *
0019  * Within the SRAM area the following ranges are forced by the system
0020  * firmware:
0021  *
0022  * 0x000000 - 0x0003ff  diagnostic area, destroyed upon a reboot
0023  * 0x000400 - ENDofRAM  storage area, available to operating systems
0024  *
0025  * but we can't really use the available area right from 0x000400 as
0026  * the first word is used by the firmware as a status flag passed
0027  * from an operating system.  If anything but the valid data magic
0028  * ID value is found, the firmware considers the SRAM clean, i.e.
0029  * containing no valid data, and disables the battery resulting in
0030  * data being erased as soon as power is switched off.  So the choice
0031  * for the start address of the user-available is 0x001000 which is
0032  * nicely page aligned.  The area between 0x000404 and 0x000fff may
0033  * be used by the driver for own needs.
0034  *
0035  * The diagnostic area defines two status words to be read by an
0036  * operating system, a magic ID to distinguish a MS02-NV board from
0037  * anything else and a status information providing results of tests
0038  * as well as the size of SRAM available, which can be 1MiB or 2MiB
0039  * (that's what the firmware handles; no idea if 2MiB modules ever
0040  * existed).
0041  *
0042  * The firmware only handles the MS02-NV board if installed in the
0043  * last (15th) slot, so for any other location the status information
0044  * stored in the SRAM cannot be relied upon.  But from the hardware
0045  * point of view there is no problem using up to 14 such boards in a
0046  * system -- only the 1st slot needs to be filled with a DRAM module.
0047  * The MS02-NV board is ECC-protected, like other MS02 memory boards.
0048  *
0049  * The state of the battery as provided by the CSR is reflected on
0050  * the two onboard LEDs.  When facing the battery side of the board,
0051  * with the LEDs at the top left and the battery at the bottom right
0052  * (i.e. looking from the back side of the system box), their meaning
0053  * is as follows (the system has to be powered on):
0054  *
0055  * left LED     battery disable status: lit = enabled
0056  * right LED        battery condition status: lit = OK
0057  */
0058
0059 /* MS02-NV iomem register offsets. */
0060 #define MS02NV_CSR      0x400000    /* control & status register */
0061
0062 /* MS02-NV CSR status bits. */
0063 #define MS02NV_CSR_BATT_OK  0x01        /* battery OK */
0064 #define MS02NV_CSR_BATT_OFF 0x02        /* battery disabled */
0065
0066
0067 /* MS02-NV memory offsets. */
0068 #define MS02NV_DIAG     0x0003f8    /* diagnostic status */
0069 #define MS02NV_MAGIC        0x0003fc    /* MS02-NV magic ID */
0070 #define MS02NV_VALID        0x000400    /* valid data magic ID */
0071 #define MS02NV_RAM      0x001000    /* user-exposed RAM start */
0072
0073 /* MS02-NV diagnostic status bits. */
0074 #define MS02NV_DIAG_TEST    0x01        /* SRAM test done (?) */
0075 #define MS02NV_DIAG_RO      0x02        /* SRAM r/o test done */
0076 #define MS02NV_DIAG_RW      0x04        /* SRAM r/w test done */
0077 #define MS02NV_DIAG_FAIL    0x08        /* SRAM test failed */
0078 #define MS02NV_DIAG_SIZE_MASK   0xf0        /* SRAM size mask */
0079 #define MS02NV_DIAG_SIZE_SHIFT  0x10        /* SRAM size shift (left) */
0080
0081 /* MS02-NV general constants. */
0082 #define MS02NV_ID       0x03021966  /* MS02-NV magic ID value */
0083 #define MS02NV_VALID_ID     0xbd100248  /* valid data magic ID value */
0084 #define MS02NV_SLOT_SIZE    0x800000    /* size of the address space
0085                            decoded by the module */
0086
0087
0088 typedef volatile u32 ms02nv_uint;
0089
0090 struct ms02nv_private {
0091     struct mtd_info *next;
0092     struct {
0093         struct resource *module;
0094         struct resource *diag_ram;
0095         struct resource *user_ram;
0096         struct resource *csr;
0097     } resource;
0098     u_char *addr;
0099     size_t size;
0100     u_char *uaddr;
0101 };