MIPS: bcm963xx: Add Broadcom BCM963xx board nvram data structure

Broadcom BCM963xx boards have multiple nvram variants across different
SoCs with additional checksum fields added whenever the size of the
nvram was extended.

Add this structure as a header file so that multiple drivers can use it.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Jonas Gorski <jogo@openwrt.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: MIPS Mailing List <linux-mips@linux-mips.org>
Cc: MTD Maling List <linux-mtd@lists.infradead.org>
Patchwork: https://patchwork.linux-mips.org/patch/11830/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MAINTAINERS

@@ -2376,6 +2376,7 @@ F:	arch/mips/kernel/*bmips*
 F:	arch/mips/boot/dts/brcm/bcm*.dts*
 F:	drivers/irqchip/irq-bcm7*
 F:	drivers/irqchip/irq-brcmstb*
+F:	include/linux/bcm963xx_nvram.h
 
 BROADCOM TG3 GIGABIT ETHERNET DRIVER
 M:	Prashant Sreedharan <prashant@broadcom.com>

include/linux/bcm963xx_nvram.h

@@ -0,0 +1,112 @@
+#ifndef __LINUX_BCM963XX_NVRAM_H__
+#define __LINUX_BCM963XX_NVRAM_H__
+
+#include <linux/crc32.h>
+#include <linux/if_ether.h>
+#include <linux/sizes.h>
+#include <linux/types.h>
+
+/*
+ * Broadcom BCM963xx SoC board nvram data structure.
+ *
+ * The nvram structure varies in size depending on the SoC board version. Use
+ * the appropriate minimum BCM963XX_NVRAM_*_SIZE define for the information
+ * you need instead of sizeof(struct bcm963xx_nvram) as this may change.
+ */
+
+#define BCM963XX_NVRAM_V4_SIZE		300
+#define BCM963XX_NVRAM_V5_SIZE		(1 * SZ_1K)
+
+#define BCM963XX_DEFAULT_PSI_SIZE	64
+
+enum bcm963xx_nvram_nand_part {
+	BCM963XX_NVRAM_NAND_PART_BOOT = 0,
+	BCM963XX_NVRAM_NAND_PART_ROOTFS_1,
+	BCM963XX_NVRAM_NAND_PART_ROOTFS_2,
+	BCM963XX_NVRAM_NAND_PART_DATA,
+	BCM963XX_NVRAM_NAND_PART_BBT,
+
+	__BCM963XX_NVRAM_NAND_NR_PARTS
+};
+
+struct bcm963xx_nvram {
+	u32	version;
+	char	bootline[256];
+	char	name[16];
+	u32	main_tp_number;
+	u32	psi_size;
+	u32	mac_addr_count;
+	u8	mac_addr_base[ETH_ALEN];
+	u8	__reserved1[2];
+	u32	checksum_v4;
+
+	u8	__reserved2[292];
+	u32	nand_part_offset[__BCM963XX_NVRAM_NAND_NR_PARTS];
+	u32	nand_part_size[__BCM963XX_NVRAM_NAND_NR_PARTS];
+	u8	__reserved3[388];
+	u32	checksum_v5;
+};
+
+#define BCM963XX_NVRAM_NAND_PART_OFFSET(nvram, part) \
+	bcm963xx_nvram_nand_part_offset(nvram, BCM963XX_NVRAM_NAND_PART_ ##part)
+
+static inline u64 __pure bcm963xx_nvram_nand_part_offset(
+	const struct bcm963xx_nvram *nvram,
+	enum bcm963xx_nvram_nand_part part)
+{
+	return nvram->nand_part_offset[part] * SZ_1K;
+}
+
+#define BCM963XX_NVRAM_NAND_PART_SIZE(nvram, part) \
+	bcm963xx_nvram_nand_part_size(nvram, BCM963XX_NVRAM_NAND_PART_ ##part)
+
+static inline u64 __pure bcm963xx_nvram_nand_part_size(
+	const struct bcm963xx_nvram *nvram,
+	enum bcm963xx_nvram_nand_part part)
+{
+	return nvram->nand_part_size[part] * SZ_1K;
+}
+
+/*
+ * bcm963xx_nvram_checksum - Verify nvram checksum
+ *
+ * @nvram: pointer to full size nvram data structure
+ * @expected_out: optional pointer to store expected checksum value
+ * @actual_out: optional pointer to store actual checksum value
+ *
+ * Return: 0 if the checksum is valid, otherwise -EINVAL
+ */
+static int __maybe_unused bcm963xx_nvram_checksum(
+	const struct bcm963xx_nvram *nvram,
+	u32 *expected_out, u32 *actual_out)
+{
+	u32 expected, actual;
+	size_t len;
+
+	if (nvram->version <= 4) {
+		expected = nvram->checksum_v4;
+		len = BCM963XX_NVRAM_V4_SIZE - sizeof(u32);
+	} else {
+		expected = nvram->checksum_v5;
+		len = BCM963XX_NVRAM_V5_SIZE - sizeof(u32);
+	}
+
+	/*
+	 * Calculate the CRC32 value for the nvram with a checksum value
+	 * of 0 without modifying or copying the nvram by combining:
+	 * - The CRC32 of the nvram without the checksum value
+	 * - The CRC32 of a zero checksum value (which is also 0)
+	 */
+	actual = crc32_le_combine(
+		crc32_le(~0, (u8 *)nvram, len), 0, sizeof(u32));
+
+	if (expected_out)
+		*expected_out = expected;
+
+	if (actual_out)
+		*actual_out = actual;
+
+	return expected == actual ? 0 : -EINVAL;
+};
+
+#endif /* __LINUX_BCM963XX_NVRAM_H__ */