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1/* SPDX-License-Identifier: GPL-2.0-or-later */2/*3 * Copyright (c) 2001, 2003 Maciej W. Rozycki4 *5 * DEC MS02-NV (54-20948-01) battery backed-up NVRAM module for6 * DECstation/DECsystem 5000/2x0 and DECsystem 5900 and 5900/2607 * 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 SRAM17 * 0x400000 - 0x7fffff CSR18 *19 * Within the SRAM area the following ranges are forced by the system20 * firmware:21 *22 * 0x000000 - 0x0003ff diagnostic area, destroyed upon a reboot23 * 0x000400 - ENDofRAM storage area, available to operating systems24 *25 * but we can't really use the available area right from 0x000400 as26 * the first word is used by the firmware as a status flag passed27 * from an operating system. If anything but the valid data magic28 * ID value is found, the firmware considers the SRAM clean, i.e.29 * containing no valid data, and disables the battery resulting in30 * data being erased as soon as power is switched off. So the choice31 * for the start address of the user-available is 0x001000 which is32 * nicely page aligned. The area between 0x000404 and 0x000fff may33 * be used by the driver for own needs.34 *35 * The diagnostic area defines two status words to be read by an36 * operating system, a magic ID to distinguish a MS02-NV board from37 * anything else and a status information providing results of tests38 * as well as the size of SRAM available, which can be 1MiB or 2MiB39 * (that's what the firmware handles; no idea if 2MiB modules ever40 * existed).41 *42 * The firmware only handles the MS02-NV board if installed in the43 * last (15th) slot, so for any other location the status information44 * stored in the SRAM cannot be relied upon. But from the hardware45 * point of view there is no problem using up to 14 such boards in a46 * 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 on50 * 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 right52 * (i.e. looking from the back side of the system box), their meaning53 * is as follows (the system has to be powered on):54 *55 * left LED battery disable status: lit = enabled56 * right LED battery condition status: lit = OK57 */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 space85 decoded by the module */86 87 88typedef volatile u32 ms02nv_uint;89 90struct 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