/*
- * Copyright (c) 2001 Maciej W. Rozycki
+ * Copyright (c) 2001, 2003 Maciej W. Rozycki
*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
+ * DEC MS02-NV (54-20948-01) battery backed-up NVRAM module for
+ * DECstation/DECsystem 5000/2x0 and DECsystem 5900 and 5900/260
+ * systems.
*
- * $Id: ms02-nv.h,v 1.1 2002/09/13 13:46:55 dwmw2 Exp $
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * $Id: ms02-nv.h,v 1.3 2003/08/19 09:25:36 dwmw2 Exp $
*/
#include <linux/ioport.h>
#include <linux/mtd/mtd.h>
+/*
+ * Addresses are decoded as follows:
+ *
+ * 0x000000 - 0x3fffff SRAM
+ * 0x400000 - 0x7fffff CSR
+ *
+ * Within the SRAM area the following ranges are forced by the system
+ * firmware:
+ *
+ * 0x000000 - 0x0003ff diagnostic area, destroyed upon a reboot
+ * 0x000400 - ENDofRAM storage area, available to operating systems
+ *
+ * but we can't really use the available area right from 0x000400 as
+ * the first word is used by the firmware as a status flag passed
+ * from an operating system. If anything but the valid data magic
+ * ID value is found, the firmware considers the SRAM clean, i.e.
+ * containing no valid data, and disables the battery resulting in
+ * data being erased as soon as power is switched off. So the choice
+ * for the start address of the user-available is 0x001000 which is
+ * nicely page aligned. The area between 0x000404 and 0x000fff may
+ * be used by the driver for own needs.
+ *
+ * The diagnostic area defines two status words to be read by an
+ * operating system, a magic ID to distinguish a MS02-NV board from
+ * anything else and a status information providing results of tests
+ * as well as the size of SRAM available, which can be 1MiB or 2MiB
+ * (that's what the firmware handles; no idea if 2MiB modules ever
+ * existed).
+ *
+ * The firmware only handles the MS02-NV board if installed in the
+ * last (15th) slot, so for any other location the status information
+ * stored in the SRAM cannot be relied upon. But from the hardware
+ * point of view there is no problem using up to 14 such boards in a
+ * system -- only the 1st slot needs to be filled with a DRAM module.
+ * The MS02-NV board is ECC-protected, like other MS02 memory boards.
+ *
+ * The state of the battery as provided by the CSR is reflected on
+ * the two onboard LEDs. When facing the battery side of the board,
+ * with the LEDs at the top left and the battery at the bottom right
+ * (i.e. looking from the back side of the system box), their meaning
+ * is as follows (the system has to be powered on):
+ *
+ * left LED battery disable status: lit = enabled
+ * right LED battery condition status: lit = OK
+ */
+
/* MS02-NV iomem register offsets. */
#define MS02NV_CSR 0x400000 /* control & status register */
+/* MS02-NV CSR status bits. */
+#define MS02NV_CSR_BATT_OK 0x01 /* battery OK */
+#define MS02NV_CSR_BATT_OFF 0x02 /* battery disabled */
+
+
/* MS02-NV memory offsets. */
#define MS02NV_DIAG 0x0003f8 /* diagnostic status */
#define MS02NV_MAGIC 0x0003fc /* MS02-NV magic ID */
-#define MS02NV_RAM 0x000400 /* general-purpose RAM start */
+#define MS02NV_VALID 0x000400 /* valid data magic ID */
+#define MS02NV_RAM 0x001000 /* user-exposed RAM start */
-/* MS02-NV diagnostic status constants. */
-#define MS02NV_DIAG_SIZE_MASK 0xf0 /* RAM size mask */
-#define MS02NV_DIAG_SIZE_SHIFT 0x10 /* RAM size shift (left) */
+/* MS02-NV diagnostic status bits. */
+#define MS02NV_DIAG_TEST 0x01 /* SRAM test done (?) */
+#define MS02NV_DIAG_RO 0x02 /* SRAM r/o test done */
+#define MS02NV_DIAG_RW 0x04 /* SRAM r/w test done */
+#define MS02NV_DIAG_FAIL 0x08 /* SRAM test failed */
+#define MS02NV_DIAG_SIZE_MASK 0xf0 /* SRAM size mask */
+#define MS02NV_DIAG_SIZE_SHIFT 0x10 /* SRAM size shift (left) */
/* MS02-NV general constants. */
#define MS02NV_ID 0x03021966 /* MS02-NV magic ID value */
+#define MS02NV_VALID_ID 0xbd100248 /* valid data magic ID value */
#define MS02NV_SLOT_SIZE 0x800000 /* size of the address space
decoded by the module */
+
typedef volatile u32 ms02nv_uint;
struct ms02nv_private {
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