bcm53xx: initialize NVRAM from NVMEM driver

NVRAM access may be needed early in boot process. Reading it using mtd
happens quite late in the init process. Add NVRAM initialization to the
NVMEM driver which comes up early and depends on IO mapping only.

This is required by Linksys devices which use NVRAM content for proper
partitioning (detecting current firmware partition).

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

2 files changed, 92 insertions, 0 deletions

diff --git a/target/linux/bcm53xx/patches-5.4/800-0001-firmware-bcm47xx_nvram-support-init-from-IO-memory.patch b/target/linux/bcm53xx/patches-5.4/800-0001-firmware-bcm47xx_nvram-support-init-from-IO-memory.patch
new file mode 100644
index 0000000000..86792d6ebf
--- /dev/null
+++ b/target/linux/bcm53xx/patches-5.4/800-0001-firmware-bcm47xx_nvram-support-init-from-IO-memory.patch
@@ -0,0 +1,61 @@
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Thu, 11 Mar 2021 08:24:44 +0100
+Subject: [PATCH] firmware: bcm47xx_nvram: support init from IO memory
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+---
+ drivers/firmware/broadcom/bcm47xx_nvram.c | 17 +++++++++++++++++
+ include/linux/bcm47xx_nvram.h             |  6 ++++++
+ 2 files changed, 23 insertions(+)
+
+--- a/drivers/firmware/broadcom/bcm47xx_nvram.c
++++ b/drivers/firmware/broadcom/bcm47xx_nvram.c
+@@ -110,6 +110,23 @@ found:
+ 	return 0;
+ }
+ 
++int bcm47xx_nvram_init_from_iomem(void __iomem *nvram_start, size_t res_size)
++{
++	if (nvram_len) {
++		pr_warn("nvram already initialized\n");
++		return -EEXIST;
++	}
++
++	if (!bcm47xx_nvram_is_valid(nvram_start)) {
++		pr_err("No valid NVRAM found\n");
++		return -ENOENT;
++	}
++
++	bcm47xx_nvram_copy(nvram_start, res_size);
++
++	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
+--- a/include/linux/bcm47xx_nvram.h
++++ b/include/linux/bcm47xx_nvram.h
+@@ -11,6 +11,7 @@
+ #include <linux/vmalloc.h>
+ 
+ #ifdef CONFIG_BCM47XX_NVRAM
++int bcm47xx_nvram_init_from_iomem(void __iomem *nvram_start, size_t res_size);
+ int bcm47xx_nvram_init_from_mem(u32 base, u32 lim);
+ int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len);
+ int bcm47xx_nvram_gpio_pin(const char *name);
+@@ -20,6 +21,11 @@ static inline void bcm47xx_nvram_release
+ 	vfree(nvram);
+ };
+ #else
++static inline int bcm47xx_nvram_init_from_iomem(void __iomem *nvram_start,
++						size_t res_size)
++{
++	return -ENOTSUPP;
++}
+ static inline int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
+ {
+ 	return -ENOTSUPP;
diff --git a/target/linux/bcm53xx/patches-5.4/800-0002-nvmem-brcm_nvram-provide-NVMEM-content-to-the-NVRAM-.patch b/target/linux/bcm53xx/patches-5.4/800-0002-nvmem-brcm_nvram-provide-NVMEM-content-to-the-NVRAM-.patch
new file mode 100644
index 0000000000..cf5952ad5f
--- /dev/null
+++ b/target/linux/bcm53xx/patches-5.4/800-0002-nvmem-brcm_nvram-provide-NVMEM-content-to-the-NVRAM-.patch
@@ -0,0 +1,31 @@
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Thu, 11 Mar 2021 08:26:14 +0100
+Subject: [PATCH] nvmem: brcm_nvram: provide NVMEM content to the NVRAM driver
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+---
+ drivers/nvmem/brcm_nvram.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/drivers/nvmem/brcm_nvram.c
++++ b/drivers/nvmem/brcm_nvram.c
+@@ -3,6 +3,7 @@
+  * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
+  */
+ 
++#include <linux/bcm47xx_nvram.h>
+ #include <linux/io.h>
+ #include <linux/mod_devicetable.h>
+ #include <linux/module.h>
+@@ -46,6 +47,8 @@ static int brcm_nvram_probe(struct platf
+ 	if (IS_ERR(priv->base))
+ 		return PTR_ERR(priv->base);
+ 
++	bcm47xx_nvram_init_from_iomem(priv->base, resource_size(res));
++
+ 	config.dev = dev;
+ 	config.priv = priv;
+ 	config.size = resource_size(res);