[PATCH 0/4] nvmem: add support for the MediaTek mt6323 PMIC

[PATCH 0/4] 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 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 (4):
      dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE
      nvmem: add mt6323 PMIC EFUSE driver
      mfd: mt6397-core: add mt6323 EFUSE support
      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/mfd/mt6397-core.c                          |  3 +
 drivers/nvmem/Kconfig                              | 11 +++
 drivers/nvmem/Makefile                             |  2 +
 drivers/nvmem/mt6323-efuse.c                       | 85 ++++++++++++++++++++++
 7 files changed, 131 insertions(+)
---
base-commit: 028ef9c96e96197026887c0f092424679298aae8
change-id: 20260611-mt6323-nvmem-0c54a0f2fa9f

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

[PATCH 1/4] 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>
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 05c121b0cb3d..beaa67bf0df2 100644
--- a/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
+++ b/Documentation/devicetree/bindings/mfd/mediatek,mt6397.yaml
@@ -145,6 +145,23 @@ 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
@@ -243,6 +260,10 @@ examples:
         interrupt-controller;
         #interrupt-cells = <2>;
 
+        efuse {
+          compatible = "mediatek,mt6323-efuse";
+        };
+
         leds {
             compatible = "mediatek,mt6323-led";
             #address-cells = <1>;

-- 
2.54.0

Re: [PATCH 1/4] dt-bindings: mfd: mediatek: mt6397: add mt6323 PMIC EFUSE

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The `efuse` subnode acts as an NVMEM provider but fails to reference the common NVMEM provider schema (`/schemas/nvmem/nvmem.yaml#`).
--

commit 6bc9ae8fe8f4cc07cc7210883f39574a57c6be49
Author: Roman Vivchar <rva333@protonmail.com>

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

This commit adds the device tree binding documentation for the MediaTek
mt6323 EFUSE, which is included in the mt6323 PMIC for storing calibration
data.

> 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
[ ... ]
> @@ -145,6 +145,23 @@ properties:
>      required:
>        - compatible
>  
> +  efuse:
> +    type: object
> +    unevaluatedProperties: false

[Severity: Low]
Does this subnode need a reference to the common NVMEM provider schema?

Because unevaluatedProperties is set to false, any standard NVMEM properties
such as read-only, #address-cells, or #size-cells will trigger schema
validation errors if added to a device tree. Including a reference to
/schemas/nvmem/nvmem.yaml# would allow these standard properties to pass
validation.

> +    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
> +

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260611-mt6323-nvmem-v1-0-b5e1b9ce51f2@protonmail.com?part=1

[PATCH 2/4] 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)
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 d1cc0e12fe1f..910360f148c4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16256,6 +16256,11 @@ 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 74ddbd0f79b0..db248a3c4e87 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -227,6 +227,17 @@ 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 7252b8ec88d4..0e2b73f42b25 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -48,6 +48,8 @@ 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..c6fbfd96ac04
--- /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/err.h>
+#include <linux/mod_devicetable.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;
+	u32 tmp;
+	u16 *buf = val;
+	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

Re: [PATCH 2/4] nvmem: add mt6323 PMIC EFUSE driver

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Blind dereference of `dev->parent->parent` can lead to a kernel panic if the device is not instantiated with the expected MFD hierarchy.
--

commit 227574270c722d2b535d72fadcf31ba55bc47f8e
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. It introduces a new nvmem driver that reads 24 bytes of
hardware-related data using regmap over the PMIC wrapper.

> diff --git a/drivers/nvmem/mt6323-efuse.c b/drivers/nvmem/mt6323-efuse.c
> new file mode 100644
> index 0000000000000..c6fbfd96ac047
> --- /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]
Is it possible for dev->parent to be NULL here?

Because the driver defines an of_match_table, it might be instantiated directly
by the OF core or bound manually via sysfs, bypassing the MFD subsystem.

If dev->parent is NULL, evaluating dev->parent->parent will cause an immediate
NULL pointer dereference. Furthermore, if dev->parent is valid but has no
parent, dev->parent->parent evaluates to NULL. Passing a NULL device pointer to
dev_get_regmap() causes a fatal NULL pointer dereference inside devres_find()
when it attempts to acquire the devres_lock.

Would it be safer to explicitly verify that both dev->parent and
dev->parent->parent are non-NULL before dereferencing them?

> +	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);
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260611-mt6323-nvmem-v1-0-b5e1b9ce51f2@protonmail.com?part=2

[PATCH 3/4] mfd: mt6397-core: add mt6323 EFUSE support

[Roman Vivchar via B4 Relay]

From: Roman Vivchar <rva333@protonmail.com>

The mt6323 PMIC includes an EFUSE. Register the EFUSE in the mt6323
devices array to allow the corresponding driver to probe using compatible
string.

Tested-by: Ben Grisdale <bengris32@protonmail.ch> # Amazon Echo Dot (2nd Generation)
Signed-off-by: Roman Vivchar <rva333@protonmail.com>
---
 drivers/mfd/mt6397-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mfd/mt6397-core.c b/drivers/mfd/mt6397-core.c
index 3e58d0764c7e..362737a1c4a9 100644
--- a/drivers/mfd/mt6397-core.c
+++ b/drivers/mfd/mt6397-core.c
@@ -125,6 +125,9 @@ static const struct resource mt6323_pwrc_resources[] = {
 
 static const struct mfd_cell mt6323_devs[] = {
 	{
+		.name = "mt6323-efuse",
+		.of_compatible = "mediatek,mt6323-efuse",
+	}, {
 		.name = "mt6323-rtc",
 		.num_resources = ARRAY_SIZE(mt6323_rtc_resources),
 		.resources = mt6323_rtc_resources,

-- 
2.54.0

[PATCH 4/4] 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