bcm53xx: add testing support for kernel 5.10

It still requires fixing PCIe support:
[    6.644699] pcie_iproc_bcma bcma0:7: host bridge /axi@18000000/pcie@12000 ranges:
[    6.652217] pcie_iproc_bcma bcma0:7:   No bus range found for /axi@18000000/pcie@12000, using [bus 00-ff]
[    6.661833] OF: /axi@18000000/pcie@12000: Missing device_type
[    6.667622] pcie_iproc_bcma: probe of bcma0:7 failed with error -12
[    6.673985] pcie_iproc_bcma bcma0:8: host bridge /axi@18000000/pcie@13000 ranges:
[    6.681514] pcie_iproc_bcma bcma0:8:   No bus range found for /axi@18000000/pcie@13000, using [bus 00-ff]
[    6.691137] pcie_iproc_bcma: probe of bcma0:8 failed with error -12
[    6.697522] pcie_iproc_bcma bcma0:9: host bridge /axi@18000000/pcie@14000 ranges:
[    6.705048] pcie_iproc_bcma bcma0:9:   No bus range found for /axi@18000000/pcie@14000, using [bus 00-ff]
[    6.714669] pcie_iproc_bcma: probe of bcma0:9 failed with error -12

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

1 files changed, 61 insertions, 0 deletions

diff --git a/target/linux/bcm53xx/patches-5.10/800-0001-firmware-bcm47xx_nvram-support-init-from-IO-memory.patch b/target/linux/bcm53xx/patches-5.10/800-0001-firmware-bcm47xx_nvram-support-init-from-IO-memory.patch
new file mode 100644
index 0000000000..86792d6ebf
--- /dev/null
+++ b/target/linux/bcm53xx/patches-5.10/800-0001-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;