MIPS: BCM47xx: Move NVRAM driver to the drivers/firmware/

After Broadcom switched from MIPS to ARM for their home routers we need
to have NVRAM driver in some common place (not arch/mips/). As explained
in Kconfig, this driver is responsible for parsing SoC configuration
data that is passed to the kernel in flash from the bootloader firmware
called "CFE".

We were thinking about putting it in bus directory, however there are
two possible buses for MIPS: drivers/ssb/ and drivers/bcma/. So this
won't fit there and this is why I would like to move this driver to the
drivers/firmware/.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Reviewed-by: Paul Walmsley <paul@pwsan.com>
Cc: linux-mips@linux-mips.org
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mike Waychison <mikew@google.com>
Cc: Roy Franz <roy.franz@linaro.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Patchwork: https://patchwork.linux-mips.org/patch/10544/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 248 insertions, 0 deletions

diff --git a/drivers/firmware/broadcom/bcm47xx_nvram.c b/drivers/firmware/broadcom/bcm47xx_nvram.c
new file mode 100644
index 000000000000..87add3fdce52
--- /dev/null
+++ b/drivers/firmware/broadcom/bcm47xx_nvram.c
@@ -0,0 +1,248 @@
+/*
+ * BCM947xx nvram variable access
+ *
+ * Copyright (C) 2005 Broadcom Corporation
+ * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de>
+ *
+ * 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/io.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/mtd/mtd.h>
+#include <linux/bcm47xx_nvram.h>
+
+#define NVRAM_MAGIC			0x48534C46	/* 'FLSH' */
+#define NVRAM_SPACE			0x10000
+#define NVRAM_MAX_GPIO_ENTRIES		32
+#define NVRAM_MAX_GPIO_VALUE_LEN	30
+
+#define FLASH_MIN		0x00020000	/* Minimum flash size */
+
+struct nvram_header {
+	u32 magic;
+	u32 len;
+	u32 crc_ver_init;	/* 0:7 crc, 8:15 ver, 16:31 sdram_init */
+	u32 config_refresh;	/* 0:15 sdram_config, 16:31 sdram_refresh */
+	u32 config_ncdl;	/* ncdl values for memc */
+};
+
+static char nvram_buf[NVRAM_SPACE];
+static size_t nvram_len;
+static const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
+
+static u32 find_nvram_size(void __iomem *end)
+{
+	struct nvram_header __iomem *header;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
+		header = (struct nvram_header *)(end - nvram_sizes[i]);
+		if (header->magic == NVRAM_MAGIC)
+			return nvram_sizes[i];
+	}
+
+	return 0;
+}
+
+/* Probe for NVRAM header */
+static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
+{
+	struct nvram_header __iomem *header;
+	int i;
+	u32 off;
+	u32 *src, *dst;
+	u32 size;
+
+	if (nvram_len) {
+		pr_warn("nvram already initialized\n");
+		return -EEXIST;
+	}
+
+	/* TODO: when nvram is on nand flash check for bad blocks first. */
+	off = FLASH_MIN;
+	while (off <= lim) {
+		/* Windowed flash access */
+		size = find_nvram_size(iobase + off);
+		if (size) {
+			header = (struct nvram_header *)(iobase + off - size);
+			goto found;
+		}
+		off <<= 1;
+	}
+
+	/* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
+	header = (struct nvram_header *)(iobase + 4096);
+	if (header->magic == NVRAM_MAGIC) {
+		size = NVRAM_SPACE;
+		goto found;
+	}
+
+	header = (struct nvram_header *)(iobase + 1024);
+	if (header->magic == NVRAM_MAGIC) {
+		size = NVRAM_SPACE;
+		goto found;
+	}
+
+	pr_err("no nvram found\n");
+	return -ENXIO;
+
+found:
+	src = (u32 *)header;
+	dst = (u32 *)nvram_buf;
+	for (i = 0; i < sizeof(struct nvram_header); i += 4)
+		*dst++ = __raw_readl(src++);
+	header = (struct nvram_header *)nvram_buf;
+	nvram_len = header->len;
+	if (nvram_len > size) {
+		pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
+		nvram_len = size;
+	}
+	if (nvram_len >= NVRAM_SPACE) {
+		pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
+		       header->len, NVRAM_SPACE - 1);
+		nvram_len = NVRAM_SPACE - 1;
+	}
+	/* proceed reading data after header */
+	for (; i < nvram_len; i += 4)
+		*dst++ = readl(src++);
+	nvram_buf[NVRAM_SPACE - 1] = '\0';
+
+	return 0;
+}
+
+/*
+ * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
+ * subsystem to access flash. We can't even use platform device / driver to
+ * store memory offset.
+ * To handle this we provide following symbol. It's supposed to be called as
+ * soon as we get info about flash device, before any NVRAM entry is needed.
+ */
+int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
+{
+	void __iomem *iobase;
+	int err;
+
+	iobase = ioremap_nocache(base, lim);
+	if (!iobase)
+		return -ENOMEM;
+
+	err = nvram_find_and_copy(iobase, lim);
+
+	iounmap(iobase);
+
+	return err;
+}
+
+static int nvram_init(void)
+{
+#ifdef CONFIG_MTD
+	struct mtd_info *mtd;
+	struct nvram_header header;
+	size_t bytes_read;
+	int err;
+
+	mtd = get_mtd_device_nm("nvram");
+	if (IS_ERR(mtd))
+		return -ENODEV;
+
+	err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
+	if (!err && header.magic == NVRAM_MAGIC &&
+	    header.len > sizeof(header)) {
+		nvram_len = header.len;
+		if (nvram_len >= NVRAM_SPACE) {
+			pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
+				header.len, NVRAM_SPACE);
+			nvram_len = NVRAM_SPACE - 1;
+		}
+
+		err = mtd_read(mtd, 0, nvram_len, &nvram_len,
+			       (u8 *)nvram_buf);
+		return err;
+	}
+#endif
+
+	return -ENXIO;
+}
+
+int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
+{
+	char *var, *value, *end, *eq;
+	int err;
+
+	if (!name)
+		return -EINVAL;
+
+	if (!nvram_len) {
+		err = nvram_init();
+		if (err)
+			return err;
+	}
+
+	/* Look for name=value and return value */
+	var = &nvram_buf[sizeof(struct nvram_header)];
+	end = nvram_buf + sizeof(nvram_buf);
+	while (var < end && *var) {
+		eq = strchr(var, '=');
+		if (!eq)
+			break;
+		value = eq + 1;
+		if (eq - var == strlen(name) &&
+		    strncmp(var, name, eq - var) == 0)
+			return snprintf(val, val_len, "%s", value);
+		var = value + strlen(value) + 1;
+	}
+	return -ENOENT;
+}
+EXPORT_SYMBOL(bcm47xx_nvram_getenv);
+
+int bcm47xx_nvram_gpio_pin(const char *name)
+{
+	int i, err;
+	char nvram_var[] = "gpioXX";
+	char buf[NVRAM_MAX_GPIO_VALUE_LEN];
+
+	/* TODO: Optimize it to don't call getenv so many times */
+	for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
+		err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
+		if (err <= 0)
+			continue;
+		err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
+		if (err <= 0)
+			continue;
+		if (!strcmp(name, buf))
+			return i;
+	}
+	return -ENOENT;
+}
+EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
+
+char *bcm47xx_nvram_get_contents(size_t *nvram_size)
+{
+	int err;
+	char *nvram;
+
+	if (!nvram_len) {
+		err = nvram_init();
+		if (err)
+			return NULL;
+	}
+
+	*nvram_size = nvram_len - sizeof(struct nvram_header);
+	nvram = vmalloc(*nvram_size);
+	if (!nvram)
+		return NULL;
+	memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
+
+	return nvram;
+}
+EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
+
+MODULE_LICENSE("GPLv2");