[PATCH v4 0/7] Read MAC address from SST vendor specific SFDP region

[PATCH v4 0/7] Read MAC address from SST vendor specific SFDP region

[Manikandan Muralidharan]

Some Microchip/SST QSPI flashes (e.g. the SST26VF064BEUI) are factory
programmed with globally unique, write-protected EUI-48 and EUI-64
identifiers stored in a vendor-specific SFDP parameter table. On boards
that have no on-board EEPROM (sama5d27_wlsom1, sama5d29 curiosity,
sam9x75 curiosity) this is a reliable source for an Ethernet MAC address,
instead of relying on a U-Boot-provided or random address.

This v4 reworks the approach into a generic NVMEM framework with no vendor
code in the SPI NOR core:
 - The SPI NOR core now exposes the entire SFDP as a generic read-only
   NVMEM device, rooted at a new "sfdp" child node of the flash.
 - A new NVMEM layout driver (drivers/nvmem/layouts/) locates the
   Microchip vendor parameter table at runtime and presents the EUI-48 as
   a "mac-address" cell.
 - Arbitrary parameters can be read with a standard fixed-layout
   (known offset) or with an nvmem-layout parser (location discovered at runtime).

Changes in v4:
 - Rework per v3 review: remove the vendor-specific SFDP handling from the
   SPI NOR core; expose the whole SFDP as a generic read-only NVMEM device
   and move the EUI extraction into an nvmem-layout driver.
 - Introduce a new nvmem-layout driver to discover the vendor-table location
   at runtime; no offset hardcoded in the device tree.
 - Describe the SFDP via a dedicated "sfdp" subnode (compatible
   "jedec,sfdp"), which also resolves the v3 dtbs_check "Unevaluated
   properties ('nvmem-layout')" warning.
 - Reverse the stored EUI bytes into canonical MAC order.
 - Enable the layout in sama5_defconfig.

 Changes in v3:
 - 2/3 - add support to update the QSPI partition into 'fixed-partition'
   binding in sama5d27_wlsom1
 - 3/3 - add nvmem-layout in qspi node for EUI48 MAC Address and nvmem cell
   properties for macb node in sama5d27_wlsom1

Changes in v2:
 - 1/3 - parse the SST vendor table, read and store the addresses
  into a resource - managed space. Register the addresses
  into NVMEM framework
 - 2/3 - add support to update the QSPI partition into 'fixed-partition'
  binding

v3: https://lore.kernel.org/linux-arm-kernel/20250521070336.402202-1-manikandan.m@microchip.com/

Manikandan Muralidharan (7):
  dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via
    NVMEM
  dt-bindings: nvmem: layouts: add Microchip/SST SFDP EUI layout
  mtd: spi-nor: sfdp: expose the SFDP as a read-only NVMEM device
  nvmem: layouts: add Microchip/SST SFDP EUI layout driver
  ARM: dts: microchip: sama5d27_wlsom1: use fixed-partitions for QSPI
    flash
  ARM: dts: microchip: sama5d27_wlsom1: read MAC address from QSPI SFDP
  ARM: configs: sama5: enable Microchip/SST SFDP EUI NVMEM layout

 .../bindings/mtd/jedec,spi-nor.yaml           |  18 ++
 .../layouts/microchip,sst26vf-sfdp-eui.yaml   |  60 ++++++
 .../bindings/nvmem/layouts/nvmem-layout.yaml  |   1 +
 MAINTAINERS                                   |   6 +
 .../dts/microchip/at91-sama5d27_wlsom1.dtsi   |  61 +++---
 .../dts/microchip/at91-sama5d27_wlsom1_ek.dts |   2 +
 arch/arm/configs/sama5_defconfig              |   1 +
 drivers/mtd/spi-nor/core.c                    |   5 +
 drivers/mtd/spi-nor/core.h                    |   1 +
 drivers/mtd/spi-nor/sfdp.c                    |  83 ++++++++
 drivers/nvmem/layouts/Kconfig                 |  10 +
 drivers/nvmem/layouts/Makefile                |   1 +
 drivers/nvmem/layouts/sst26vf-sfdp-eui.c      | 182 ++++++++++++++++++
 13 files changed, 409 insertions(+), 22 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/nvmem/layouts/microchip,sst26vf-sfdp-eui.yaml
 create mode 100644 drivers/nvmem/layouts/sst26vf-sfdp-eui.c


base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
-- 
2.43.0

[PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Manikandan Muralidharan]

Add an optional "sfdp" child node (compatible "jedec,sfdp") that
describes the SFDP as a read-only NVMEM provider via nvmem.yaml, so its
contents (e.g. a vendor EUI-48/EUI-64) can be read through NVMEM cells.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 .../devicetree/bindings/mtd/jedec,spi-nor.yaml | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
index 587af4968255..98fd954598ab 100644
--- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
+++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
@@ -103,6 +103,20 @@ properties:
   spi-cpol: true
   spi-cpha: true
 
+  sfdp:
+    $ref: /schemas/nvmem/nvmem.yaml#
+    unevaluatedProperties: false
+    description:
+      The Serial Flash Discoverable Parameters (SFDP) tables exposed as a
+      read-only NVMEM device. This allows standard or vendor-specific SFDP
+      data (for example a factory-programmed EUI-48/EUI-64 identifier) to be
+      consumed through NVMEM cells.
+    properties:
+      compatible:
+        const: jedec,sfdp
+    required:
+      - compatible
+
 dependencies:
   spi-cpol: [ spi-cpha ]
   spi-cpha: [ spi-cpol ]
@@ -122,6 +136,10 @@ examples:
             spi-max-frequency = <40000000>;
             m25p,fast-read;
             reset-gpios = <&gpio 12 GPIO_ACTIVE_LOW>;
+
+            sfdp {
+                compatible = "jedec,sfdp";
+            };
         };
     };
 ...
-- 
2.43.0

[PATCH v4 2/7] dt-bindings: nvmem: layouts: add Microchip/SST SFDP EUI layout

[Manikandan Muralidharan]

Add a binding for the NVMEM layout that exposes the factory-programmed
EUI-48 identifier from the Microchip/SST vendor-specific SFDP parameter
table (e.g. SST26VF064BEUI) as a "mac-address" NVMEM cell, and reference
it from nvmem-layout.yaml.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 .../layouts/microchip,sst26vf-sfdp-eui.yaml   | 60 +++++++++++++++++++
 .../bindings/nvmem/layouts/nvmem-layout.yaml  |  1 +
 2 files changed, 61 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/layouts/microchip,sst26vf-sfdp-eui.yaml

diff --git a/Documentation/devicetree/bindings/nvmem/layouts/microchip,sst26vf-sfdp-eui.yaml b/Documentation/devicetree/bindings/nvmem/layouts/microchip,sst26vf-sfdp-eui.yaml
new file mode 100644
index 000000000000..37357efb7840
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/layouts/microchip,sst26vf-sfdp-eui.yaml
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/layouts/microchip,sst26vf-sfdp-eui.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NVMEM layout of the Microchip/SST SFDP EUI-48 identifier
+
+maintainers:
+  - Manikandan Muralidharan <manikandan.m@microchip.com>
+
+description:
+  Some Microchip/SST serial flashes (for example the SST26VF064BEUI) are
+  factory programmed with a globally unique EUI-48 identifier stored in a
+  vendor-specific SFDP parameter table and permanently write-protected. This
+  layout locates that table and exposes the EUI-48 as an NVMEM cell so that,
+  for example, a network driver can use it as a MAC address. The location of
+  the data is discovered at runtime from the SFDP; no offset is encoded in the
+  device tree.
+
+select: false
+
+properties:
+  compatible:
+    const: microchip,sst26vf-sfdp-eui
+
+  mac-address:
+    type: object
+    description:
+      The factory-programmed EUI-48 identifier, usable as a MAC address.
+    additionalProperties: false
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        flash@0 {
+            compatible = "jedec,spi-nor";
+            reg = <0>;
+
+            sfdp {
+                compatible = "jedec,sfdp";
+
+                nvmem-layout {
+                    compatible = "microchip,sst26vf-sfdp-eui";
+
+                    mac-address {
+                    };
+                };
+            };
+        };
+    };
+...
diff --git a/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml b/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml
index 382507060651..e63b93083821 100644
--- a/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml
+++ b/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml
@@ -20,6 +20,7 @@ description: |
 oneOf:
   - $ref: fixed-layout.yaml
   - $ref: kontron,sl28-vpd.yaml
+  - $ref: microchip,sst26vf-sfdp-eui.yaml
   - $ref: onie,tlv-layout.yaml
   - $ref: u-boot,env.yaml
 
-- 
2.43.0

[PATCH v4 3/7] mtd: spi-nor: sfdp: expose the SFDP as a read-only NVMEM device

[Manikandan Muralidharan]

Register the cached SFDP as a read-only NVMEM device rooted at the
flash's "sfdp" child node, exposing it in on-flash byte order. This lets
NVMEM cells reference any SFDP data: a fixed-layout for parameters at a
known offset, or an nvmem-layout parser for vendor data whose location
must be discovered at runtime. The device is only registered when an
"sfdp" node is present in the device tree.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 drivers/mtd/spi-nor/core.c |  5 +++
 drivers/mtd/spi-nor/core.h |  1 +
 drivers/mtd/spi-nor/sfdp.c | 83 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index ccf4396cdcd0..e04ba3e3dee9 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3204,6 +3204,11 @@ static int spi_nor_init_params(struct spi_nor *nor)
 		spi_nor_init_params_deprecated(nor);
 	}
 
+	/* Expose the SFDP as an NVMEM device. */
+	ret = spi_nor_register_sfdp_nvmem(nor);
+	if (ret)
+		return ret;
+
 	ret = spi_nor_late_init_params(nor);
 	if (ret)
 		return ret;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index ba2d1a862c9d..0a6484298c5c 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -698,6 +698,7 @@ int spi_nor_controller_ops_write_reg(struct spi_nor *nor, u8 opcode,
 
 int spi_nor_check_sfdp_signature(struct spi_nor *nor);
 int spi_nor_parse_sfdp(struct spi_nor *nor);
+int spi_nor_register_sfdp_nvmem(struct spi_nor *nor);
 
 static inline struct spi_nor *mtd_to_spi_nor(struct mtd_info *mtd)
 {
diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index 4600983cb579..2df818bca6b5 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -6,6 +6,8 @@
 
 #include <linux/bitfield.h>
 #include <linux/mtd/spi-nor.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/sort.h>
 
@@ -1612,3 +1614,84 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
 	kfree(param_headers);
 	return err;
 }
+
+static int spi_nor_sfdp_nvmem_read(void *priv, unsigned int offset,
+				   void *val, size_t bytes)
+{
+	struct spi_nor *nor = priv;
+	struct sfdp *sfdp = nor->sfdp;
+	size_t sfdp_size = sfdp->num_dwords * sizeof(*sfdp->dwords);
+
+	if (offset >= sfdp_size || bytes > sfdp_size - offset)
+		return -EINVAL;
+
+	/* The cached SFDP is kept in on-flash (little-endian) byte order. */
+	memcpy(val, (u8 *)sfdp->dwords + offset, bytes);
+
+	return 0;
+}
+
+static void spi_nor_sfdp_nvmem_put_np(void *data)
+{
+	of_node_put(data);
+}
+
+/**
+ * spi_nor_register_sfdp_nvmem() - expose the SFDP as a read-only NVMEM device
+ * @nor:	pointer to a 'struct spi_nor'
+ *
+ * Expose the whole SFDP, in on-flash byte order, as a read-only NVMEM device
+ * rooted at the flash's "sfdp" child node. This lets generic (fixed-layout) or
+ * vendor (nvmem-layout) cells reference any SFDP data. The device is only
+ * registered when an "sfdp" node is described in the device tree.
+ *
+ * Return: 0 on success or if there is nothing to do, -errno otherwise.
+ */
+int spi_nor_register_sfdp_nvmem(struct spi_nor *nor)
+{
+	struct device *dev = nor->dev;
+	struct nvmem_config config = { };
+	struct nvmem_device *nvmem;
+	struct device_node *np;
+	int ret;
+
+	if (!nor->sfdp)
+		return 0;
+
+	np = of_get_child_by_name(dev_of_node(dev), "sfdp");
+	if (!np)
+		return 0;
+
+	/*
+	 * Register the put before devm_nvmem_register() so it runs last on
+	 * detach, after the NVMEM device that uses the node is gone.
+	 */
+	ret = devm_add_action_or_reset(dev, spi_nor_sfdp_nvmem_put_np, np);
+	if (ret)
+		return ret;
+
+	config.dev = dev;
+	config.of_node = np;
+	config.name = "sfdp";
+	config.id = NVMEM_DEVID_AUTO;
+	config.owner = THIS_MODULE;
+	config.read_only = true;
+	config.word_size = 1;
+	config.stride = 1;
+	config.size = (int)(nor->sfdp->num_dwords * sizeof(*nor->sfdp->dwords));
+	config.reg_read = spi_nor_sfdp_nvmem_read;
+	config.priv = nor;
+
+	nvmem = devm_nvmem_register(dev, &config);
+	if (IS_ERR(nvmem)) {
+		/* NVMEM support is optional. */
+		if (PTR_ERR(nvmem) == -EOPNOTSUPP)
+			return 0;
+		return dev_err_probe(dev, PTR_ERR(nvmem),
+				     "failed to register SFDP NVMEM device\n");
+	}
+
+	dev_dbg(dev, "exposed %d-byte SFDP as an NVMEM device\n", config.size);
+
+	return 0;
+}
-- 
2.43.0

[PATCH v4 4/7] nvmem: layouts: add Microchip/SST SFDP EUI layout driver

[Manikandan Muralidharan]

Add an NVMEM layout that exposes the factory-programmed EUI-48 identifier
from the Microchip/SST vendor SFDP parameter table (e.g. SST26VF064BEUI)
as a "mac-address" cell, for use as a network MAC address. The vendor
table is located at runtime via the SFDP NVMEM device (no offset in DT),
and a read_post_process callback reverses the LSB-first bytes into
canonical MAC order. Binds to an "nvmem-layout" node with compatible
"microchip,sst26vf-sfdp-eui".

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 MAINTAINERS                              |   6 +
 drivers/nvmem/layouts/Kconfig            |  10 ++
 drivers/nvmem/layouts/Makefile           |   1 +
 drivers/nvmem/layouts/sst26vf-sfdp-eui.c | 182 +++++++++++++++++++++++
 4 files changed, 199 insertions(+)
 create mode 100644 drivers/nvmem/layouts/sst26vf-sfdp-eui.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 15011f5752a9..dc3411b0c3b5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17812,6 +17812,12 @@ F:	Documentation/devicetree/bindings/sound/atmel,at91-ssc.yaml
 F:	drivers/misc/atmel-ssc.c
 F:	include/linux/atmel-ssc.h
 
+MICROCHIP SST SFDP EUI NVMEM LAYOUT DRIVER
+M:	Manikandan Muralidharan <manikandan.m@microchip.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/nvmem/layouts/microchip,sst26vf-sfdp-eui.yaml
+F:	drivers/nvmem/layouts/sst26vf-sfdp-eui.c
+
 Microchip Timer Counter Block (TCB) Capture Driver
 M:	Kamel Bouhara <kamel.bouhara@bootlin.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
diff --git a/drivers/nvmem/layouts/Kconfig b/drivers/nvmem/layouts/Kconfig
index 5e586dfebe47..855c7db530da 100644
--- a/drivers/nvmem/layouts/Kconfig
+++ b/drivers/nvmem/layouts/Kconfig
@@ -26,6 +26,16 @@ config NVMEM_LAYOUT_ONIE_TLV
 
 	  If unsure, say N.
 
+config NVMEM_LAYOUT_SST26VF_SFDP_EUI
+	tristate "Microchip/SST SFDP EUI-48 layout support"
+	help
+	  Say Y here if you want to expose the factory-programmed EUI-48
+	  identifier stored in the Microchip/SST vendor-specific SFDP parameter
+	  table (e.g. SST26VF064BEUI) as NVMEM cells, so that network drivers
+	  can use them as a MAC address.
+
+	  If unsure, say N.
+
 config NVMEM_LAYOUT_U_BOOT_ENV
 	tristate "U-Boot environment variables layout"
 	select CRC32
diff --git a/drivers/nvmem/layouts/Makefile b/drivers/nvmem/layouts/Makefile
index 4940c9db0665..b99eac1f63f2 100644
--- a/drivers/nvmem/layouts/Makefile
+++ b/drivers/nvmem/layouts/Makefile
@@ -5,4 +5,5 @@
 
 obj-$(CONFIG_NVMEM_LAYOUT_SL28_VPD) += sl28vpd.o
 obj-$(CONFIG_NVMEM_LAYOUT_ONIE_TLV) += onie-tlv.o
+obj-$(CONFIG_NVMEM_LAYOUT_SST26VF_SFDP_EUI) += sst26vf-sfdp-eui.o
 obj-$(CONFIG_NVMEM_LAYOUT_U_BOOT_ENV) += u-boot-env.o
diff --git a/drivers/nvmem/layouts/sst26vf-sfdp-eui.c b/drivers/nvmem/layouts/sst26vf-sfdp-eui.c
new file mode 100644
index 000000000000..641318d6f0af
--- /dev/null
+++ b/drivers/nvmem/layouts/sst26vf-sfdp-eui.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NVMEM layout for the factory-programmed EUI-48 identifier stored in the
+ * Microchip/SST vendor-specific SFDP parameter table (e.g. SST26VF064BEUI).
+ *
+ * The whole SFDP is exposed as a read-only NVMEM device by the SPI NOR core.
+ * This layout locates the Microchip vendor parameter table at runtime and
+ * registers the EUI-48 address as an NVMEM cell, so that a network driver can
+ * consume it as a MAC address. No offset is hardcoded in the device tree.
+ *
+ * Copyright (C) 2026 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Manikandan Muralidharan <manikandan.m@microchip.com>
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/minmax.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/unaligned.h>
+#include <uapi/linux/if_ether.h>
+
+/* SFDP header and parameter header, as laid out on the flash. */
+struct sfdp_header {
+	u8 signature[4];
+	u8 minor;
+	u8 major;
+	u8 nph;
+	u8 unused;
+};
+
+struct sfdp_parameter_header {
+	u8 id_lsb;
+	u8 minor;
+	u8 major;
+	u8 length;
+	u8 parameter_table_pointer[3];
+	u8 id_msb;
+};
+
+#define SFDP_SIGNATURE			0x50444653U
+
+#define SFDP_PARAM_HEADER_ID(h)		(((h)->id_msb << 8) | (h)->id_lsb)
+#define SFDP_PARAM_HEADER_PTP(h)	get_unaligned_le24((h)->parameter_table_pointer)
+
+/* Microchip (vendor) parameter table identifier: id_msb << 8 | id_lsb. */
+#define SFDP_MCHP_VENDOR_ID		0x01bf
+
+#define SFDP_MCHP_EUI48_MARKER_OFFSET	0x60
+#define SFDP_MCHP_EUI48_MARKER		0x30
+#define SFDP_MCHP_EUI48_OFFSET		0x61
+
+static int sfdp_eui_read_post_process(void *priv, const char *id, int index,
+				      unsigned int offset, void *buf,
+				      size_t bytes)
+{
+	u8 *data = buf;
+	int i;
+
+	/* SFDP stores the address least-significant octet first; reverse it. */
+	for (i = 0; i < bytes / 2; i++)
+		swap(data[i], data[bytes - 1 - i]);
+
+	if (bytes == ETH_ALEN && !is_valid_ether_addr(buf))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int sfdp_eui_find_vendor_table(struct nvmem_device *nvmem, u32 *ptp)
+{
+	struct sfdp_parameter_header ph;
+	struct sfdp_header hdr;
+	int nph, i, ret;
+
+	ret = nvmem_device_read(nvmem, 0, sizeof(hdr), &hdr);
+	if (ret < 0)
+		return ret;
+
+	if (get_unaligned_le32(hdr.signature) != SFDP_SIGNATURE)
+		return -EINVAL;
+
+	/* The number of parameter headers (NPH) field is zero-based. */
+	nph = hdr.nph;
+
+	for (i = 0; i <= nph; i++) {
+		ret = nvmem_device_read(nvmem, sizeof(hdr) + i * sizeof(ph),
+					sizeof(ph), &ph);
+		if (ret < 0)
+			return ret;
+
+		if (SFDP_PARAM_HEADER_ID(&ph) != SFDP_MCHP_VENDOR_ID)
+			continue;
+
+		*ptp = SFDP_PARAM_HEADER_PTP(&ph);
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+static int sfdp_eui_add_cells(struct nvmem_layout *layout)
+{
+	struct nvmem_device *nvmem = layout->nvmem;
+	struct device *dev = &layout->dev;
+	struct nvmem_cell_info info = { };
+	struct device_node *layout_np;
+	u32 base = 0;
+	u8 marker;
+	int ret;
+
+	ret = sfdp_eui_find_vendor_table(nvmem, &base);
+	if (ret == -ENOENT) {
+		dev_dbg(dev, "no Microchip SFDP vendor table found\n");
+		return 0;
+	}
+	if (ret)
+		return ret;
+
+	/* The EUI-48 is present only if its marker byte is programmed. */
+	ret = nvmem_device_read(nvmem, base + SFDP_MCHP_EUI48_MARKER_OFFSET,
+				1, &marker);
+	if (ret < 0)
+		return ret;
+	if (marker != SFDP_MCHP_EUI48_MARKER) {
+		dev_dbg(dev, "EUI-48 not programmed (marker 0x%02x)\n", marker);
+		return 0;
+	}
+
+	layout_np = of_nvmem_layout_get_container(nvmem);
+	if (!layout_np)
+		return -ENOENT;
+
+	info.name = "mac-address";
+	info.offset = base + SFDP_MCHP_EUI48_OFFSET;
+	info.bytes = ETH_ALEN;
+	info.np = of_get_child_by_name(layout_np, "mac-address");
+	info.read_post_process = sfdp_eui_read_post_process;
+
+	ret = nvmem_add_one_cell(nvmem, &info);
+	if (ret)
+		of_node_put(info.np);
+	else
+		dev_dbg(dev, "exposed EUI-48 at SFDP offset 0x%x\n", info.offset);
+
+	of_node_put(layout_np);
+
+	return ret;
+}
+
+static int sfdp_eui_probe(struct nvmem_layout *layout)
+{
+	layout->add_cells = sfdp_eui_add_cells;
+
+	return nvmem_layout_register(layout);
+}
+
+static void sfdp_eui_remove(struct nvmem_layout *layout)
+{
+	nvmem_layout_unregister(layout);
+}
+
+static const struct of_device_id sfdp_eui_of_match_table[] = {
+	{ .compatible = "microchip,sst26vf-sfdp-eui" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sfdp_eui_of_match_table);
+
+static struct nvmem_layout_driver sfdp_eui_layout = {
+	.driver = {
+		.name = "microchip-sst26vf-sfdp-eui-layout",
+		.of_match_table = sfdp_eui_of_match_table,
+	},
+	.probe = sfdp_eui_probe,
+	.remove = sfdp_eui_remove,
+};
+module_nvmem_layout_driver(sfdp_eui_layout);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Manikandan Muralidharan <manikandan.m@microchip.com>");
+MODULE_DESCRIPTION("NVMEM layout for the EUI-48 in the Microchip/SST SFDP vendor table");
-- 
2.43.0

[PATCH v4 5/7] ARM: dts: microchip: sama5d27_wlsom1: use fixed-partitions for QSPI flash

[Manikandan Muralidharan]

Move the QSPI flash partitions under a "partitions" node with the
"fixed-partitions" compatible, as required by the current MTD partition
binding, instead of declaring them as direct children of the flash node.
No functional change.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 .../dts/microchip/at91-sama5d27_wlsom1.dtsi   | 52 +++++++++++--------
 1 file changed, 29 insertions(+), 23 deletions(-)

diff --git a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi
index 0417f53b3e96..062aa02a98ed 100644
--- a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi
+++ b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi
@@ -240,34 +240,40 @@ qspi1_flash: flash@0 {
 		m25p,fast-read;
 		status = "disabled";
 
-		at91bootstrap@0 {
-			label = "at91bootstrap";
-			reg = <0x0 0x40000>;
-		};
+		partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			at91bootstrap@0 {
+				label = "at91bootstrap";
+				reg = <0x0 0x40000>;
+			};
 
-		bootloader@40000 {
-			label = "bootloader";
-			reg = <0x40000 0xc0000>;
-		};
+			bootloader@40000 {
+				label = "bootloader";
+				reg = <0x40000 0xc0000>;
+			};
 
-		bootloaderenvred@100000 {
-			label = "bootloader env redundant";
-			reg = <0x100000 0x40000>;
-		};
+			bootloaderenvred@100000 {
+				label = "bootloader env redundant";
+				reg = <0x100000 0x40000>;
+			};
 
-		bootloaderenv@140000 {
-			label = "bootloader env";
-			reg = <0x140000 0x40000>;
-		};
+			bootloaderenv@140000 {
+				label = "bootloader env";
+				reg = <0x140000 0x40000>;
+			};
 
-		dtb@180000 {
-			label = "device tree";
-			reg = <0x180000 0x80000>;
-		};
+			dtb@180000 {
+				label = "device tree";
+				reg = <0x180000 0x80000>;
+			};
 
-		kernel@200000 {
-			label = "kernel";
-			reg = <0x200000 0x600000>;
+			kernel@200000 {
+				label = "kernel";
+				reg = <0x200000 0x600000>;
+			};
 		};
 	};
 };
-- 
2.43.0

[PATCH v4 6/7] ARM: dts: microchip: sama5d27_wlsom1: read MAC address from QSPI SFDP

[Manikandan Muralidharan]

Describe the QSPI flash SFDP as an NVMEM provider with the
microchip,sst26vf-sfdp-eui layout, which exposes the factory-programmed
EUI-48 as a "mac-address" cell, and point macb0 at it through
nvmem-cells. This yields a stable MAC address on boards where U-Boot does
not program one, instead of falling back to a random address.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi | 11 +++++++++++
 .../boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts    |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi
index 062aa02a98ed..6016d7f2a39c 100644
--- a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi
+++ b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1.dtsi
@@ -240,6 +240,17 @@ qspi1_flash: flash@0 {
 		m25p,fast-read;
 		status = "disabled";
 
+		sfdp {
+			compatible = "jedec,sfdp";
+
+			nvmem-layout {
+				compatible = "microchip,sst26vf-sfdp-eui";
+
+				mac_address_eui48: mac-address {
+				};
+			};
+		};
+
 		partitions {
 			compatible = "fixed-partitions";
 			#address-cells = <1>;
diff --git a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts
index 35a933eec573..5e87bf04bc47 100644
--- a/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts
+++ b/arch/arm/boot/dts/microchip/at91-sama5d27_wlsom1_ek.dts
@@ -97,6 +97,8 @@ uart6: serial@200 {
 
 &macb0 {
 	status = "okay";
+	nvmem-cells = <&mac_address_eui48>;
+	nvmem-cell-names = "mac-address";
 };
 
 &pioA {
-- 
2.43.0

[PATCH v4 7/7] ARM: configs: sama5: enable Microchip/SST SFDP EUI NVMEM layout

[Manikandan Muralidharan]

Enable CONFIG_NVMEM_LAYOUT_SST26VF_SFDP_EUI so the factory EUI-48 stored
in the SST26VF QSPI flash SFDP can be used as a MAC address on boards
such as the sama5d27_wlsom1.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 arch/arm/configs/sama5_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/sama5_defconfig b/arch/arm/configs/sama5_defconfig
index bd7f0b5f7d66..14dda4b0cfd0 100644
--- a/arch/arm/configs/sama5_defconfig
+++ b/arch/arm/configs/sama5_defconfig
@@ -220,6 +220,7 @@ CONFIG_PWM=y
 CONFIG_PWM_ATMEL=y
 CONFIG_PWM_ATMEL_HLCDC_PWM=y
 CONFIG_PWM_ATMEL_TCB=y
+CONFIG_NVMEM_LAYOUT_SST26VF_SFDP_EUI=y
 CONFIG_EXT4_FS=y
 CONFIG_FANOTIFY=y
 CONFIG_AUTOFS_FS=m
-- 
2.43.0

Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Linus Walleij]

Hi Manikandan,

thanks for your patch!

On Tue, Jun 30, 2026 at 11:24 AM Manikandan Muralidharan
<manikandan.m@microchip.com> wrote:

> Add an optional "sfdp" child node (compatible "jedec,sfdp") that
> describes the SFDP as a read-only NVMEM provider via nvmem.yaml, so its
> contents (e.g. a vendor EUI-48/EUI-64) can be read through NVMEM cells.
>
> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>

I would expect it to follow nvmem conventions like this, notice
compatibles specific-to-general with sfdp first:

sfdp {
    /* NVMEM provided by SFDP */
    compatible = "jedec,sfdp", "nvmem-cells";
    label = "SFDP";
    read-only;
    #address-cells = <1>;
    #size-cells = <1>;

    mac0: macaddr@0x00 {
        reg = <0x00 0x06>;
    };
    mac1: macaddr@0x06 {
        reg = <0x06 0x06>;
    };
};

Your example should definitely be more elaborate like this,
just an opaque sfdp node will not suffice. Maybe a separate
example?

Yours,
Linus Walleij

Re: [PATCH v4 3/7] mtd: spi-nor: sfdp: expose the SFDP as a read-only NVMEM device

[Linus Walleij]

Hi Manikandan,

thanks for your patch!

On Tue, Jun 30, 2026 at 11:25 AM Manikandan Muralidharan
<manikandan.m@microchip.com> wrote:

> Register the cached SFDP as a read-only NVMEM device rooted at the
> flash's "sfdp" child node, exposing it in on-flash byte order. This lets
> NVMEM cells reference any SFDP data: a fixed-layout for parameters at a
> known offset, or an nvmem-layout parser for vendor data whose location
> must be discovered at runtime. The device is only registered when an
> "sfdp" node is present in the device tree.

It seems the existing serial NOR driver core already reads out the SFDP
and stores it in  nor->sfdp->dwords, right?

This should be mentioned in the commit so we know when the stuff
is actually read in from the flash memory.

>
> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
(...)

> @@ -3204,6 +3204,11 @@ static int spi_nor_init_params(struct spi_nor *nor)
>                 spi_nor_init_params_deprecated(nor);
>         }
>
> +       /* Expose the SFDP as an NVMEM device. */

Add "if and only if the flash has an SFDP"

> +static int spi_nor_sfdp_nvmem_read(void *priv, unsigned int offset,
> +                                  void *val, size_t bytes)

Name it _reg_read() to mirror the nvmem prototype.

> +/**
> + * spi_nor_register_sfdp_nvmem() - expose the SFDP as a read-only NVMEM device
> + * @nor:       pointer to a 'struct spi_nor'
> + *
> + * Expose the whole SFDP, in on-flash byte order, as a read-only NVMEM device
> + * rooted at the flash's "sfdp" child node. This lets generic (fixed-layout) or
> + * vendor (nvmem-layout) cells reference any SFDP data. The device is only
> + * registered when an "sfdp" node is described in the device tree.
> + *
> + * Return: 0 on success or if there is nothing to do, -errno otherwise.
> + */
> +int spi_nor_register_sfdp_nvmem(struct spi_nor *nor)
> +{
> +       struct device *dev = nor->dev;
> +       struct nvmem_config config = { };
> +       struct nvmem_device *nvmem;
> +       struct device_node *np;
> +       int ret;
> +
> +       if (!nor->sfdp)
> +               return 0;
> +
> +       np = of_get_child_by_name(dev_of_node(dev), "sfdp");
> +       if (!np)
> +               return 0;

If this node name is required to be named like that it has to be
enforced in the schema.

I would instead check all the nodes (for_each_available_child)
for the right compatible "jedec,sfdp".

Yours,
Linus Walleij

Re: [PATCH v4 5/7] ARM: dts: microchip: sama5d27_wlsom1: use fixed-partitions for QSPI flash

[Linus Walleij]

On Tue, Jun 30, 2026 at 11:26 AM Manikandan Muralidharan
<manikandan.m@microchip.com> wrote:

> Move the QSPI flash partitions under a "partitions" node with the
> "fixed-partitions" compatible, as required by the current MTD partition
> binding, instead of declaring them as direct children of the flash node.
> No functional change.
>
> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>

Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Michael Walle]

[-- Attachment #1: Type: text/plain, Size: 1630 bytes --]

Hi,

>> Add an optional "sfdp" child node (compatible "jedec,sfdp") that
>> describes the SFDP as a read-only NVMEM provider via nvmem.yaml, so its
>> contents (e.g. a vendor EUI-48/EUI-64) can be read through NVMEM cells.
>>
>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
>
> I would expect it to follow nvmem conventions like this, notice
> compatibles specific-to-general with sfdp first:


> sfdp {
>     /* NVMEM provided by SFDP */
>     compatible = "jedec,sfdp", "nvmem-cells";
>     label = "SFDP";

Isn't using label frowned upon? I wouldn't add that to the example.

>     read-only;
>     #address-cells = <1>;
>     #size-cells = <1>;
>
>     mac0: macaddr@0x00 {
>         reg = <0x00 0x06>;
>     };
>     mac1: macaddr@0x06 {
>         reg = <0x06 0x06>;
>     };
> };

If I'm correct, this is the old style, see commit bd912c991d2e
("dt-bindings: nvmem: layouts: add fixed-layout"). So it should
eventually look like:

sfdp {
     compatible = "jedec,sfdp";

     nvmem-layout {
	     compatible = "microchip,sst26vf-sfdp-eui";
     };
};

Which is what patch series will lead to.

Also I'm not sure if we really need to add the "nvmem-cells" here.
IIRC in MTD it was there to tell a driver to add an nvmem device to
an already existing compatible/node.

Apart from the MTD case, I've just found qcom,smem-part,yaml which
has compatible = "nvmem-cells".

-michael

> Your example should definitely be more elaborate like this,
> just an opaque sfdp node will not suffice. Maybe a separate
> example?
>
> Yours,
> Linus Walleij


[-- Attachment #2: signature.asc --]
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Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Linus Walleij]

On Wed, Jul 1, 2026 at 10:34 AM Michael Walle <michael@walle.cc> wrote:

> If I'm correct, this is the old style, see commit bd912c991d2e
> ("dt-bindings: nvmem: layouts: add fixed-layout"). So it should
> eventually look like:
>
> sfdp {
>      compatible = "jedec,sfdp";
(...)
> Also I'm not sure if we really need to add the "nvmem-cells" here.
> IIRC in MTD it was there to tell a driver to add an nvmem device to
> an already existing compatible/node.
>
> Apart from the MTD case, I've just found qcom,smem-part,yaml which
> has compatible = "nvmem-cells".

You're right, I was using old information, discard my comments...
Reviewed-by: Linus Walleij <linusw@kernel.org>

I think my comment in the driver to check for the compatible
instead of the node name is still valid though.

Yours,
Linus Walleij

Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Manikandan.M]

On 7/1/26 4:23 PM, Linus Walleij wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Wed, Jul 1, 2026 at 10:34 AM Michael Walle <michael@walle.cc> wrote:
> 
>> If I'm correct, this is the old style, see commit bd912c991d2e
>> ("dt-bindings: nvmem: layouts: add fixed-layout"). So it should
>> eventually look like:
>>
>> sfdp {
>>       compatible = "jedec,sfdp";
> (...)
>> Also I'm not sure if we really need to add the "nvmem-cells" here.
>> IIRC in MTD it was there to tell a driver to add an nvmem device to
>> an already existing compatible/node.
>>
>> Apart from the MTD case, I've just found qcom,smem-part,yaml which
>> has compatible = "nvmem-cells".
> 
> You're right, I was using old information, discard my comments...
> Reviewed-by: Linus Walleij <linusw@kernel.org>
> 
> I think my comment in the driver to check for the compatible
> instead of the node name is still valid though.
Thank you Linus Wallejj and Michael.
I will address the driver changes in the next version.
> 
> Yours,
> Linus Walleij


-- 
Thanks and Regards,
Manikandan M.

Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Krzysztof Kozlowski]

On Tue, Jun 30, 2026 at 02:54:00PM +0530, Manikandan Muralidharan wrote:
> Add an optional "sfdp" child node (compatible "jedec,sfdp") that
> describes the SFDP as a read-only NVMEM provider via nvmem.yaml, so its

What is SFDP?

> contents (e.g. a vendor EUI-48/EUI-64) can be read through NVMEM cells.
> 
> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
> ---
>  .../devicetree/bindings/mtd/jedec,spi-nor.yaml | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> index 587af4968255..98fd954598ab 100644
> --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> @@ -103,6 +103,20 @@ properties:
>    spi-cpol: true
>    spi-cpha: true
>  
> +  sfdp:
> +    $ref: /schemas/nvmem/nvmem.yaml#
> +    unevaluatedProperties: false
> +    description:
> +      The Serial Flash Discoverable Parameters (SFDP) tables exposed as a
> +      read-only NVMEM device. This allows standard or vendor-specific SFDP
> +      data (for example a factory-programmed EUI-48/EUI-64 identifier) to be
> +      consumed through NVMEM cells.
> +    properties:
> +      compatible:
> +        const: jedec,sfdp
> +    required:
> +      - compatible

Where are any resources? What sort of sub-device is represented here by
an empty device node?

Best regards,
Krzysztof

Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Manikandan.M]

Hi Krzysztof,

On 7/2/26 11:46 AM, Krzysztof Kozlowski wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Tue, Jun 30, 2026 at 02:54:00PM +0530, Manikandan Muralidharan wrote:
>> Add an optional "sfdp" child node (compatible "jedec,sfdp") that
>> describes the SFDP as a read-only NVMEM provider via nvmem.yaml, so its
> 
> What is SFDP?
> 
SFDP is the Serial Flash Discoverable Parameters -- a JEDEC-standardised
(JESD216) read-only parameter table present in most SPI NOR flashes, the 
table contents provide basic information about the flash. There are 
standard tables which are specified by the JEDEC standard and there are 
vendor tables.
>> contents (e.g. a vendor EUI-48/EUI-64) can be read through NVMEM cells.
>>
>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
>> ---
>>   .../devicetree/bindings/mtd/jedec,spi-nor.yaml | 18 ++++++++++++++++++
>>   1 file changed, 18 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
>> index 587af4968255..98fd954598ab 100644
>> --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
>> +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
>> @@ -103,6 +103,20 @@ properties:
>>     spi-cpol: true
>>     spi-cpha: true
>>
>> +  sfdp:
>> +    $ref: /schemas/nvmem/nvmem.yaml#
>> +    unevaluatedProperties: false
>> +    description:
>> +      The Serial Flash Discoverable Parameters (SFDP) tables exposed as a
>> +      read-only NVMEM device. This allows standard or vendor-specific SFDP
>> +      data (for example a factory-programmed EUI-48/EUI-64 identifier) to be
>> +      consumed through NVMEM cells.
>> +    properties:
>> +      compatible:
>> +        const: jedec,sfdp
>> +    required:
>> +      - compatible
> 
> Where are any resources? What sort of sub-device is represented here by
> an empty device node?
The sub-device describes the flash's SFDP region exposed as a read-only 
NVMEM provider:the SPI NOR core reads the SFDP and registers it as an 
NVMEM device rooted at this node.Its contents are then consumed through 
NVMEM cells -- a "fixed-layout" for data at a known offset, or an 
"nvmem-layout" parser for data whose location must be discovered at 
runtime (the Microchip EUI layout driver in patch 4/7 does the latter).
It is not a bus-addressed hardware sub-device, so it has no reg.

This models the SFDP-as-NVMEM approach suggested during the v3 review, 
instead of special-casing the vendor table in the SPI NOR core:

https://lore.kernel.org/linux-arm-kernel/20250521070336.402202-1-manikandan.m@microchip.com/
> 
> Best regards,
> Krzysztof
> 


-- 
Thanks and Regards,
Manikandan M.

Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM

[Rob Herring]

On Thu, Jul 02, 2026 at 06:55:15AM +0000, Manikandan.M@microchip.com wrote:
> Hi Krzysztof,
> 
> On 7/2/26 11:46 AM, Krzysztof Kozlowski wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On Tue, Jun 30, 2026 at 02:54:00PM +0530, Manikandan Muralidharan wrote:
> >> Add an optional "sfdp" child node (compatible "jedec,sfdp") that
> >> describes the SFDP as a read-only NVMEM provider via nvmem.yaml, so its
> > 
> > What is SFDP?
> > 
> SFDP is the Serial Flash Discoverable Parameters -- a JEDEC-standardised
> (JESD216) read-only parameter table present in most SPI NOR flashes, the 
> table contents provide basic information about the flash. There are 
> standard tables which are specified by the JEDEC standard and there are 
> vendor tables.

Is SFDP present or not discoverable? Or we have a table of discoverable 
parameters that itself is not discoverable.

If it is discoverable, why does this need to be in DT?

Rob