MIPS: BCM47xx: Add NVRAM support devices

When trying to netboot a Linksys WRT54GS WLAN router, the bootup fails,
because of following error message:

...
[    0.424000] b44: b44.c:v2.0
[    0.424000] b44: Invalid MAC address found in EEPROM
[    0.432000] b44 ssb0:1: Problem fetching invariants of chip,aborting
[    0.436000] b44: probe of ssb0:1 failed with error -22
...

The router uses a CFE bootloader, but most of the needed environment
variables for network card initialization, are not available from CFE
via printenv and even though not via cfe_getenv().
The required environment variables are saved in a special partition
in flash memory. The attached patch implement nvram_getenv and enables
bootup via NFS root on my router.

Most of the patch is extracted from the OpenWrt subversion repository and
stripped down and cleaned up to just fix this issue.

[Ralf: sorted out header file inclusions.  Lots of unneded headers and such
that should have been included.]

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Reviewed-by: Phil Sutter <phil@nwl.cc>
To: linux-mips@linux-mips.org
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: http://patchwork.linux-mips.org/patch/1359/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 94 insertions, 0 deletions

diff --git a/arch/mips/bcm47xx/nvram.c b/arch/mips/bcm47xx/nvram.c
new file mode 100644
index 0000000..06e03b2
--- /dev/null
+++ b/arch/mips/bcm47xx/nvram.c
@@ -0,0 +1,94 @@
+/*
+ * BCM947xx nvram variable access
+ *
+ * Copyright (C) 2005 Broadcom Corporation
+ * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
+ *
+ * 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.
+ */
+
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/ssb/ssb.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <asm/addrspace.h>
+#include <asm/mach-bcm47xx/nvram.h>
+#include <asm/mach-bcm47xx/bcm47xx.h>
+
+static char nvram_buf[NVRAM_SPACE];
+
+/* Probe for NVRAM header */
+static void __init early_nvram_init(void)
+{
+	struct ssb_mipscore *mcore = &ssb_bcm47xx.mipscore;
+	struct nvram_header *header;
+	int i;
+	u32 base, lim, off;
+	u32 *src, *dst;
+
+	base = mcore->flash_window;
+	lim = mcore->flash_window_size;
+
+	off = FLASH_MIN;
+	while (off <= lim) {
+		/* Windowed flash access */
+		header = (struct nvram_header *)
+			KSEG1ADDR(base + off - NVRAM_SPACE);
+		if (header->magic == NVRAM_HEADER)
+			goto found;
+		off <<= 1;
+	}
+
+	/* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
+	header = (struct nvram_header *) KSEG1ADDR(base + 4096);
+	if (header->magic == NVRAM_HEADER)
+		goto found;
+
+	header = (struct nvram_header *) KSEG1ADDR(base + 1024);
+	if (header->magic == NVRAM_HEADER)
+		goto found;
+
+	return;
+
+found:
+	src = (u32 *) header;
+	dst = (u32 *) nvram_buf;
+	for (i = 0; i < sizeof(struct nvram_header); i += 4)
+		*dst++ = *src++;
+	for (; i < header->len && i < NVRAM_SPACE; i += 4)
+		*dst++ = le32_to_cpu(*src++);
+}
+
+int nvram_getenv(char *name, char *val, size_t val_len)
+{
+	char *var, *value, *end, *eq;
+
+	if (!name)
+		return 1;
+
+	if (!nvram_buf[0])
+		early_nvram_init();
+
+	/* Look for name=value and return value */
+	var = &nvram_buf[sizeof(struct nvram_header)];
+	end = nvram_buf + sizeof(nvram_buf) - 2;
+	end[0] = end[1] = '\0';
+	for (; *var; var = value + strlen(value) + 1) {
+		eq = strchr(var, '=');
+		if (!eq)
+			break;
+		value = eq + 1;
+		if ((eq - var) == strlen(name) &&
+			strncmp(var, name, (eq - var)) == 0) {
+			snprintf(val, val_len, "%s", value);
+			return 0;
+		}
+	}
+	return 1;
+}
+EXPORT_SYMBOL(nvram_getenv);