[PATCH v3 0/3] nvmem: add support for the MediaTek mt6323 PMIC

[PATCH v3 0/3] nvmem: add support for the MediaTek mt6323 PMIC

[Roman Vivchar via B4 Relay]

This series adds support for the EFUSE found on the MediaTek mt6323 PMIC.

The previous version of the series for all AUXADC, EFUSE and thermal
drivers was split after Krzysztof's comment [1].
    
Tested on the MediaTek mt6572 and mt8163 SoCs (Ben), both paired with a
mt6323.

[1]: https://lore.kernel.org/linux-mediatek/20260504-mt6323-v1-0-799b58b355ff@protonmail.com/T/#med30fad67a090be35f549231336b2dec295233f6

Tested-by: Ben Grisdale <bengris32@protonmail.ch> # Amazon Echo Dot (2nd Generation)
Signed-off-by: Roman Vivchar <rva333@protonmail.com>

---
Changes in v3:
- Rebase onto next-20260708
- EFUSE driver: Replace 'mod_devicetable.h' with explicit 'device-id/of.h'
- Drop MFD patch since it's applied
- Link to v2: https://patch.msgid.link/20260617-mt6323-nvmem-v2-0-4f30e36aa0f4@protonmail.com

Changes in v2:
- EFUSE driver: Sort variables in the mt6323_efuse_read (Andy)
- Link to v1: https://patch.msgid.link/20260611-mt6323-nvmem-v1-0-b5e1b9ce51f2@protonmail.com

Changes after split:
- EFUSE driver:
    - Remove 'linux/errno.h' header (Andy)
    - Remove explicit cast to u16 in the 'mt6323_efuse_read' (Andy)
    - Reword comment in the 'mt6323_efuse_read'
    - Capitalize MediaTek in the module description
- Link to a previous series: https://patch.msgid.link/20260512-mt6323-v2-0-3efcba579e88@protonmail.com

---
Roman Vivchar (3):
      dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE
      nvmem: add mt6323 PMIC EFUSE driver
      ARM: dts: mediatek: mt6323: add EFUSE support

 .../devicetree/bindings/mfd/mediatek,mt6397.yaml   | 21 ++++++
 MAINTAINERS                                        |  5 ++
 arch/arm/boot/dts/mediatek/mt6323.dtsi             |  4 +
 drivers/nvmem/Kconfig                              | 11 +++
 drivers/nvmem/Makefile                             |  2 +
 drivers/nvmem/mt6323-efuse.c                       | 85 ++++++++++++++++++++++
 6 files changed, 128 insertions(+)
---
base-commit: b9810cd75b9fb56a3425d391cba3f608502bd474
change-id: 20260611-mt6323-nvmem-0c54a0f2fa9f

Best regards,
--  
Roman Vivchar <rva333@protonmail.com>

[PATCH v3 1/3] dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE

[Roman Vivchar via B4 Relay]

From: Roman Vivchar <rva333@protonmail.com>

The MediaTek mt6323 PMIC includes an EFUSE used for storing calibration
data.

Add the devicetree binding documentation for the MediaTek mt6323 EFUSE.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Roman Vivchar <rva333@protonmail.com>
---
 .../devicetree/bindings/mfd/mediatek,mt6397.yaml    | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml b/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
index 3cbc0dc12c31..d2de227ae7a6 100644
--- a/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
+++ b/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
@@ -159,6 +159,23 @@ properties:
     required:
       - compatible
 
+  efuse:
+    type: object
+    unevaluatedProperties: false
+    description:
+      The efuse is responsible for storing calibration data, such as thermal
+      sensor calibration.
+
+    properties:
+      compatible:
+        const: mediatek,mt6323-efuse
+
+      nvmem-layout:
+        $ref: /schemas/nvmem/layouts/nvmem-layout.yaml#
+
+    required:
+      - compatible
+
   leds:
     type: object
     additionalProperties: false
@@ -307,6 +324,10 @@ examples:
         interrupt-controller;
         #interrupt-cells = <2>;
 
+        efuse {
+          compatible = "mediatek,mt6323-efuse";
+        };
+
         leds {
             compatible = "mediatek,mt6323-led";
             #address-cells = <1>;

-- 
2.54.0

[PATCH v3 2/3] nvmem: add mt6323 PMIC EFUSE driver

[Roman Vivchar via B4 Relay]

From: Roman Vivchar <rva333@protonmail.com>

Add support for the EFUSE controller found in the Mediatek MT6323 PMIC.
The MT6323 EFUSE stores 24 bytes of hardware-related data, such as
thermal sensor calibration values.

Tested-by: Ben Grisdale <bengris32@protonmail.ch> # Amazon Echo Dot (2nd Generation)
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Roman Vivchar <rva333@protonmail.com>
---
 MAINTAINERS                  |  5 +++
 drivers/nvmem/Kconfig        | 11 ++++++
 drivers/nvmem/Makefile       |  2 ++
 drivers/nvmem/mt6323-efuse.c | 85 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 103 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 47cfe6531719..372cc3244236 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16578,6 +16578,11 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/mmc/mtk-sd.yaml
 F:	drivers/mmc/host/mtk-sd.c
 
+MEDIATEK MT6323 PMIC NVMEM DRIVER
+M:	Roman Vivchar <rva333@protonmail.com>
+S:	Maintained
+F:	drivers/nvmem/mt6323-efuse.c
+
 MEDIATEK MT6735 CLOCK & RESET DRIVERS
 M:	Yassine Oudjana <y.oudjana@protonmail.com>
 L:	linux-clk@vger.kernel.org
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index e10f7ff725ff..a6b5b3e13b4e 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -240,6 +240,17 @@ config NVMEM_MTK_EFUSE
 	  This driver can also be built as a module. If so, the module
 	  will be called efuse-mtk.
 
+config NVMEM_MT6323_EFUSE
+	tristate "Mediatek MT6323 PMIC EFUSE support"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	depends on MFD_MT6397
+	help
+	  This is a driver to access hardware related data like sensor
+	  calibration, etc.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called efuse-mt6323.
+
 config NVMEM_MXS_OCOTP
 	tristate "Freescale MXS On-Chip OTP Memory Support"
 	depends on ARCH_MXS || COMPILE_TEST
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index f6f2bc51dee1..23b7552634d1 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -50,6 +50,8 @@ obj-$(CONFIG_NVMEM_MICROCHIP_OTPC)	+= nvmem-microchip-otpc.o
 nvmem-microchip-otpc-y			:= microchip-otpc.o
 obj-$(CONFIG_NVMEM_MTK_EFUSE)		+= nvmem_mtk-efuse.o
 nvmem_mtk-efuse-y			:= mtk-efuse.o
+obj-$(CONFIG_NVMEM_MT6323_EFUSE)		+= nvmem_mt6323-efuse.o
+nvmem_mt6323-efuse-y			:= mt6323-efuse.o
 obj-$(CONFIG_NVMEM_MXS_OCOTP)		+= nvmem-mxs-ocotp.o
 nvmem-mxs-ocotp-y			:= mxs-ocotp.o
 obj-$(CONFIG_NVMEM_NINTENDO_OTP)	+= nvmem-nintendo-otp.o
diff --git a/drivers/nvmem/mt6323-efuse.c b/drivers/nvmem/mt6323-efuse.c
new file mode 100644
index 000000000000..41678915d5b6
--- /dev/null
+++ b/drivers/nvmem/mt6323-efuse.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2026 Roman Vivchar <rva333@protonmail.com>
+ */
+
+#include <linux/device-id/of.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#include <linux/mfd/mt6323/registers.h>
+
+#define MT6323_EFUSE_DOUT_BASE	MT6323_EFUSE_DOUT_0_15
+#define MT6323_EFUSE_SIZE	24
+
+static int mt6323_efuse_read(void *context, unsigned int offset, void *val,
+			     size_t bytes)
+{
+	struct regmap *map = context;
+	u16 *buf = val;
+	u32 tmp;
+	int ret;
+
+	/*
+	 * A manual loop using regmap_read is required because PWRAP is not
+	 * a continuous MMIO space, but rather a FSM that doesn't implement the
+	 * necessary read callback for the regmap_read_raw and regmap_read_bulk
+	 * functions.
+	 */
+	for (size_t i = 0; i < bytes; i += sizeof(*buf)) {
+		ret = regmap_read(map, MT6323_EFUSE_DOUT_BASE + offset + i, &tmp);
+		if (ret)
+			return ret;
+
+		*buf++ = tmp;
+	}
+
+	return 0;
+}
+
+static int mt6323_efuse_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct nvmem_config config = {
+		.name = "mt6323-efuse",
+		.stride = 2,
+		.word_size = 2,
+		.size = MT6323_EFUSE_SIZE,
+		.reg_read = mt6323_efuse_read,
+	};
+	struct nvmem_device *nvmem;
+	struct regmap *regmap;
+
+	/* efuse -> mfd -> pwrap */
+	regmap = dev_get_regmap(dev->parent->parent, NULL);
+	if (!regmap)
+		return dev_err_probe(dev, -ENODEV, "failed to get regmap\n");
+
+	config.dev = dev;
+	config.priv = regmap;
+
+	nvmem = devm_nvmem_register(dev, &config);
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static const struct of_device_id mt6323_efuse_of_match[] = {
+	{ .compatible = "mediatek,mt6323-efuse" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mt6323_efuse_of_match);
+
+static struct platform_driver mt6323_efuse_driver = {
+	.probe = mt6323_efuse_probe,
+	.driver = {
+		.name = "mt6323-efuse",
+		.of_match_table = mt6323_efuse_of_match,
+	},
+};
+module_platform_driver(mt6323_efuse_driver);
+
+MODULE_DESCRIPTION("MediaTek MT6323 PMIC EFUSE driver");
+MODULE_LICENSE("GPL");

-- 
2.54.0

[PATCH v3 3/3] ARM: dts: mediatek: mt6323: add EFUSE support

[Roman Vivchar via B4 Relay]

From: Roman Vivchar <rva333@protonmail.com>

Add the devicetree node for the mt6323 efuse.

Tested-by: Ben Grisdale <bengris32@protonmail.ch> # Amazon Echo Dot (2nd Generation)
Signed-off-by: Roman Vivchar <rva333@protonmail.com>
---
 arch/arm/boot/dts/mediatek/mt6323.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/mediatek/mt6323.dtsi b/arch/arm/boot/dts/mediatek/mt6323.dtsi
index c230c865116d..807e000a7ff6 100644
--- a/arch/arm/boot/dts/mediatek/mt6323.dtsi
+++ b/arch/arm/boot/dts/mediatek/mt6323.dtsi
@@ -14,6 +14,10 @@ pmic: mt6323 {
 		interrupt-controller;
 		#interrupt-cells = <2>;
 
+		efuse {
+			compatible = "mediatek,mt6323-efuse";
+		};
+
 		mt6323_leds: leds {
 			compatible = "mediatek,mt6323-led";
 			#address-cells = <1>;

-- 
2.54.0

Re: [PATCH v3 1/3] dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The `efuse` node schema sets `unevaluatedProperties: false` but omits the reference to the standard NVMEM subsystem schema (`/schemas/nvmem/nvmem.yaml#`), rejecting valid generic NVMEM properties.
- [Low] The commit message description begins with a lowercase letter, violating MFD subsystem guidelines.
--

--- Patch [1]: [PATCH v3 1/3] dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE ---
commit 26cbf9fd727c6628394df9e87fedf646b54dc080
Author: Roman Vivchar <rva333@protonmail.com>

dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE

The MediaTek mt6323 PMIC includes an EFUSE used for storing calibration
data.

> dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE

[Severity: Low]
This isn't a bug, but the commit description starts with a lowercase letter.
Should the description after the subsystem prefix be capitalized according to
MFD subsystem conventions?

> diff --git a/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml b/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
> --- a/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
> +++ b/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
> @@ -159,6 +159,23 @@ properties:

[ ... ]

> +  efuse:
> +    type: object
> +    unevaluatedProperties: false
> +    description:
> +      The efuse is responsible for storing calibration data, such as thermal
> +      sensor calibration.
> +
> +    properties:
> +      compatible:
> +        const: mediatek,mt6323-efuse
> +
> +      nvmem-layout:
> +        $ref: /schemas/nvmem/layouts/nvmem-layout.yaml#

[Severity: Medium]
Since this node uses unevaluatedProperties: false, does it also need a
reference to the standard NVMEM schema ($ref: /schemas/nvmem/nvmem.yaml#)?

Without it, wouldn't standard NVMEM properties like read-only or wp-gpios
cause schema validation failures if they are added?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260713-mt6323-nvmem-v3-0-205c39267a24@protonmail.com?part=1

Re: [PATCH v3 2/3] nvmem: add mt6323 PMIC EFUSE driver

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The driver blindly dereferences `dev->parent->parent` to retrieve the regmap, which causes a NULL pointer dereference kernel panic if instantiated outside the expected MFD hierarchy, and violates MFD subsystem guidelines.
--

--- Patch [2]: [PATCH v3 2/3] nvmem: add mt6323 PMIC EFUSE driver ---
commit 25fbde0741e1e6a18bf5c1f7cc92f4eb70b9d17e
Author: Roman Vivchar <rva333@protonmail.com>

nvmem: add mt6323 PMIC EFUSE driver

This commit adds support for the EFUSE controller found in the Mediatek
MT6323 PMIC, which stores 24 bytes of hardware-related data.

> diff --git a/drivers/nvmem/mt6323-efuse.c b/drivers/nvmem/mt6323-efuse.c
> new file mode 100644
> index 0000000000000..41678915d5b62
> --- /dev/null
> +++ b/drivers/nvmem/mt6323-efuse.c

[ ... ]

> +static int mt6323_efuse_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct nvmem_config config = {
> +		.name = "mt6323-efuse",
> +		.stride = 2,
> +		.word_size = 2,
> +		.size = MT6323_EFUSE_SIZE,
> +		.reg_read = mt6323_efuse_read,
> +	};
> +	struct nvmem_device *nvmem;
> +	struct regmap *regmap;
> +
> +	/* efuse -> mfd -> pwrap */
> +	regmap = dev_get_regmap(dev->parent->parent, NULL);

[Severity: High]
Can this cause a NULL pointer dereference if the device is instantiated
outside the expected MFD hierarchy?

If the device is instantiated directly via a Device Tree root node overlay or
through sysfs, dev->parent could be the platform_bus. Because the
platform_bus has no parent, evaluating dev->parent->parent would result in
NULL. 

Passing NULL to dev_get_regmap() leads to an immediate kernel panic when
devres_find() unconditionally locks the devres_lock.

Additionally, MFD subsystem guidelines recommend that child drivers retrieve
data using standard APIs without relying on hard-coded assumptions about
grandparent device topology.

> +	if (!regmap)
> +		return dev_err_probe(dev, -ENODEV, "failed to get regmap\n");
> +
> +	config.dev = dev;
> +	config.priv = regmap;

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260713-mt6323-nvmem-v3-0-205c39267a24@protonmail.com?part=2