[PATCH v2 1/2] dt-bindings: nvmem: Add apple,efuses

[PATCH v2 1/2] dt-bindings: nvmem: Add apple,efuses

[Sven Peter]

Apple SoCs come with eFuses used to store factory-programmed data
such as calibration settings for the PCIe and Type-C PHY.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
v1 -> v2:
  - fixed indentation issue pointed out by Krzysztof Kozlowski

 .../bindings/nvmem/apple,efuses.yaml          | 50 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/apple,efuses.yaml

diff --git a/Documentation/devicetree/bindings/nvmem/apple,efuses.yaml b/Documentation/devicetree/bindings/nvmem/apple,efuses.yaml
new file mode 100644
index 000000000000..5ec8f2bdb3a5
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/apple,efuses.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/apple,efuses.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple SoC eFuse-based NVMEM
+
+description: |
+  Apple SoCs such as the M1 contain factory-programmed eFuses used to e.g. store
+  calibration data for the PCIe and the Type-C PHY or unique chip identifiers
+  such as the ECID.
+
+maintainers:
+  - Sven Peter <sven@svenpeter.dev>
+
+allOf:
+  - $ref: "nvmem.yaml#"
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - apple,t8103-efuses
+          - apple,t6000-efuses
+      - const: apple,efuses
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    efuse@3d2bc000 {
+        compatible = "apple,t8103-efuses", "apple,efuses";
+        reg = <0x3d2bc000 0x1000>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        ecid: efuse@500 {
+            reg = <0x500 0x8>;
+        };
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 05fd080b82f3..f70d8525cbd4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1771,6 +1771,7 @@ F:	Documentation/devicetree/bindings/arm/apple/*
 F:	Documentation/devicetree/bindings/i2c/apple,i2c.yaml
 F:	Documentation/devicetree/bindings/interrupt-controller/apple,aic.yaml
 F:	Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml
+F:	Documentation/devicetree/bindings/nvmem/apple,efuses.yaml
 F:	Documentation/devicetree/bindings/pci/apple,pcie.yaml
 F:	Documentation/devicetree/bindings/pinctrl/apple,pinctrl.yaml
 F:	Documentation/devicetree/bindings/power/apple*
-- 
2.25.1

[PATCH v2 2/2] nvmem: Add Apple eFuse driver

[Sven Peter]

Apple SoCs contain eFuses used to store factory-programmed data such
as calibration values for the PCIe or the Type-C PHY. They are organized
as 32bit values exposed as MMIO.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
v1 -> v2:
  - fixed sparse warning about __iomem by introducing
    struct apple_efuses_priv as done in other nvmem drivers
  - make sure the driver actually works as a module by
    setting .owner to THIS_MODULE and adding MODULE_DEVICE_TABLE
    pointed out by Joey Gouly

 MAINTAINERS                  |  1 +
 drivers/nvmem/Kconfig        | 12 ++++++
 drivers/nvmem/Makefile       |  2 +
 drivers/nvmem/apple-efuses.c | 82 ++++++++++++++++++++++++++++++++++++
 4 files changed, 97 insertions(+)
 create mode 100644 drivers/nvmem/apple-efuses.c

diff --git a/MAINTAINERS b/MAINTAINERS
index f70d8525cbd4..e3e973a3f651 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1781,6 +1781,7 @@ F:	drivers/i2c/busses/i2c-pasemi-core.c
 F:	drivers/i2c/busses/i2c-pasemi-platform.c
 F:	drivers/irqchip/irq-apple-aic.c
 F:	drivers/mailbox/apple-mailbox.c
+F:	drivers/nvmem/apple-efuses.c
 F:	drivers/pinctrl/pinctrl-apple-gpio.c
 F:	drivers/soc/apple/*
 F:	drivers/watchdog/apple_wdt.c
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index da414617a54d..bba29d1aec96 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -300,4 +300,16 @@ config NVMEM_BRCM_NVRAM
 	  This driver provides support for Broadcom's NVRAM that can be accessed
 	  using I/O mapping.
 
+config NVMEM_APPLE_EFUSES
+	tristate "Apple eFuse support"
+	depends on ARCH_APPLE || COMPILE_TEST
+	default ARCH_APPLE
+	help
+	  Say y here to enable support for reading eFuses on Apple SoCs
+	  such as the M1. These are e.g. used to store factory programmed
+	  calibration data required for the PCIe or the USB-C PHY.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called nvmem-apple-efuses.
+
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index dcbbde35b6a8..1a8e54691d3e 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -61,3 +61,5 @@ obj-$(CONFIG_NVMEM_RMEM) 	+= nvmem-rmem.o
 nvmem-rmem-y			:= rmem.o
 obj-$(CONFIG_NVMEM_BRCM_NVRAM)	+= nvmem_brcm_nvram.o
 nvmem_brcm_nvram-y		:= brcm_nvram.o
+obj-$(CONFIG_NVMEM_APPLE_EFUSES)	+= nvmem-apple-efuses.o
+nvmem-apple-efuses-y 		:= apple-efuses.o
diff --git a/drivers/nvmem/apple-efuses.c b/drivers/nvmem/apple-efuses.c
new file mode 100644
index 000000000000..dd5576ec5408
--- /dev/null
+++ b/drivers/nvmem/apple-efuses.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Apple SoC eFuse driver
+ *
+ * Copyright (C) The Asahi Linux Contributors
+ */
+
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+
+struct apple_efuses_priv {
+	void __iomem *fuses;
+};
+
+static int apple_efuses_read(void *context, unsigned int offset, void *val,
+			     size_t bytes)
+{
+	struct apple_efuses_priv *priv = context;
+	u32 *dst = val;
+
+	while (bytes >= sizeof(u32)) {
+		*dst++ = readl_relaxed(priv->fuses + offset);
+		bytes -= sizeof(u32);
+		offset += sizeof(u32);
+	}
+
+	return 0;
+}
+
+static int apple_efuses_probe(struct platform_device *pdev)
+{
+	struct apple_efuses_priv *priv;
+	struct resource *res;
+	struct nvmem_config config = {
+		.dev = &pdev->dev,
+		.read_only = true,
+		.reg_read = apple_efuses_read,
+		.stride = sizeof(u32),
+		.word_size = sizeof(u32),
+		.name = "apple_efuses_nvmem",
+		.id = NVMEM_DEVID_AUTO,
+		.owner = THIS_MODULE,
+		.root_only = true,
+	};
+
+	priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(priv->fuses))
+		return PTR_ERR(priv->fuses);
+
+	config.priv = priv;
+	config.size = resource_size(res);
+
+	return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
+}
+
+static const struct of_device_id apple_efuses_of_match[] = {
+	{ .compatible = "apple,efuses", },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
+
+static struct platform_driver apple_efuses_driver = {
+	.driver = {
+		.name = "apple_efuses",
+		.of_match_table = apple_efuses_of_match,
+		.owner = THIS_MODULE,
+	},
+	.probe = apple_efuses_probe,
+};
+
+module_platform_driver(apple_efuses_driver);
+
+MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
+MODULE_LICENSE("GPL");
-- 
2.25.1

Re: [PATCH v2 1/2] dt-bindings: nvmem: Add apple,efuses

[Krzysztof Kozlowski]

On 06/03/2022 13:18, Sven Peter wrote:
> Apple SoCs come with eFuses used to store factory-programmed data
> such as calibration settings for the PCIe and Type-C PHY.
> 
> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> ---
> v1 -> v2:
>   - fixed indentation issue pointed out by Krzysztof Kozlowski
> 
>  .../bindings/nvmem/apple,efuses.yaml          | 50 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  2 files changed, 51 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/nvmem/apple,efuses.yaml
> 


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>


Best regards,
Krzysztof

Re: [PATCH v2 2/2] nvmem: Add Apple eFuse driver

[Krzysztof Kozlowski]

On 06/03/2022 13:18, Sven Peter wrote:
> Apple SoCs contain eFuses used to store factory-programmed data such
> as calibration values for the PCIe or the Type-C PHY. They are organized
> as 32bit values exposed as MMIO.
> 
> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> ---
> v1 -> v2:
>   - fixed sparse warning about __iomem by introducing
>     struct apple_efuses_priv as done in other nvmem drivers
>   - make sure the driver actually works as a module by
>     setting .owner to THIS_MODULE and adding MODULE_DEVICE_TABLE
>     pointed out by Joey Gouly
> 
>  MAINTAINERS                  |  1 +
>  drivers/nvmem/Kconfig        | 12 ++++++
>  drivers/nvmem/Makefile       |  2 +
>  drivers/nvmem/apple-efuses.c | 82 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 97 insertions(+)
>  create mode 100644 drivers/nvmem/apple-efuses.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f70d8525cbd4..e3e973a3f651 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1781,6 +1781,7 @@ F:	drivers/i2c/busses/i2c-pasemi-core.c
>  F:	drivers/i2c/busses/i2c-pasemi-platform.c
>  F:	drivers/irqchip/irq-apple-aic.c
>  F:	drivers/mailbox/apple-mailbox.c
> +F:	drivers/nvmem/apple-efuses.c
>  F:	drivers/pinctrl/pinctrl-apple-gpio.c
>  F:	drivers/soc/apple/*
>  F:	drivers/watchdog/apple_wdt.c
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index da414617a54d..bba29d1aec96 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -300,4 +300,16 @@ config NVMEM_BRCM_NVRAM
>  	  This driver provides support for Broadcom's NVRAM that can be accessed
>  	  using I/O mapping.
>  
> +config NVMEM_APPLE_EFUSES
> +	tristate "Apple eFuse support"
> +	depends on ARCH_APPLE || COMPILE_TEST
> +	default ARCH_APPLE
> +	help
> +	  Say y here to enable support for reading eFuses on Apple SoCs
> +	  such as the M1. These are e.g. used to store factory programmed
> +	  calibration data required for the PCIe or the USB-C PHY.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called nvmem-apple-efuses.
> +
>  endif
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index dcbbde35b6a8..1a8e54691d3e 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -61,3 +61,5 @@ obj-$(CONFIG_NVMEM_RMEM) 	+= nvmem-rmem.o
>  nvmem-rmem-y			:= rmem.o
>  obj-$(CONFIG_NVMEM_BRCM_NVRAM)	+= nvmem_brcm_nvram.o
>  nvmem_brcm_nvram-y		:= brcm_nvram.o
> +obj-$(CONFIG_NVMEM_APPLE_EFUSES)	+= nvmem-apple-efuses.o
> +nvmem-apple-efuses-y 		:= apple-efuses.o
> diff --git a/drivers/nvmem/apple-efuses.c b/drivers/nvmem/apple-efuses.c
> new file mode 100644
> index 000000000000..dd5576ec5408
> --- /dev/null
> +++ b/drivers/nvmem/apple-efuses.c
> @@ -0,0 +1,82 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Apple SoC eFuse driver
> + *
> + * Copyright (C) The Asahi Linux Contributors
> + */
> +
> +#include <linux/io.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/nvmem-provider.h>
> +#include <linux/platform_device.h>
> +
> +struct apple_efuses_priv {
> +	void __iomem *fuses;
> +};
> +
> +static int apple_efuses_read(void *context, unsigned int offset, void *val,
> +			     size_t bytes)
> +{
> +	struct apple_efuses_priv *priv = context;
> +	u32 *dst = val;
> +
> +	while (bytes >= sizeof(u32)) {
> +		*dst++ = readl_relaxed(priv->fuses + offset);
> +		bytes -= sizeof(u32);
> +		offset += sizeof(u32);
> +	}
> +
> +	return 0;
> +}
> +
> +static int apple_efuses_probe(struct platform_device *pdev)
> +{
> +	struct apple_efuses_priv *priv;
> +	struct resource *res;
> +	struct nvmem_config config = {
> +		.dev = &pdev->dev,
> +		.read_only = true,
> +		.reg_read = apple_efuses_read,
> +		.stride = sizeof(u32),
> +		.word_size = sizeof(u32),
> +		.name = "apple_efuses_nvmem",
> +		.id = NVMEM_DEVID_AUTO,
> +		.owner = THIS_MODULE,
> +		.root_only = true,
> +	};
> +
> +	priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> +	if (IS_ERR(priv->fuses))
> +		return PTR_ERR(priv->fuses);
> +
> +	config.priv = priv;
> +	config.size = resource_size(res);
> +
> +	return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
> +}
> +
> +static const struct of_device_id apple_efuses_of_match[] = {
> +	{ .compatible = "apple,efuses", },
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
> +
> +static struct platform_driver apple_efuses_driver = {
> +	.driver = {
> +		.name = "apple_efuses",
> +		.of_match_table = apple_efuses_of_match,
> +		.owner = THIS_MODULE,

You wrote it also in changelog, but why do you need it? Doesn't core set
it? Coccinelle should complain about this as well.

Best regards,
Krzysztof

Re: [PATCH v2 2/2] nvmem: Add Apple eFuse driver

[Sven Peter]

On Sun, Mar 6, 2022, at 13:25, Krzysztof Kozlowski wrote:
> On 06/03/2022 13:18, Sven Peter wrote:
>> Apple SoCs contain eFuses used to store factory-programmed data such
>> as calibration values for the PCIe or the Type-C PHY. They are organized
>> as 32bit values exposed as MMIO.
>> 
>> Signed-off-by: Sven Peter <sven@svenpeter.dev>
>> ---
>> v1 -> v2:
>>   - fixed sparse warning about __iomem by introducing
>>     struct apple_efuses_priv as done in other nvmem drivers
>>   - make sure the driver actually works as a module by
>>     setting .owner to THIS_MODULE and adding MODULE_DEVICE_TABLE
>>     pointed out by Joey Gouly
>> 
>>  MAINTAINERS                  |  1 +
>>  drivers/nvmem/Kconfig        | 12 ++++++
>>  drivers/nvmem/Makefile       |  2 +
>>  drivers/nvmem/apple-efuses.c | 82 ++++++++++++++++++++++++++++++++++++
>>  4 files changed, 97 insertions(+)
>>  create mode 100644 drivers/nvmem/apple-efuses.c
>> 
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index f70d8525cbd4..e3e973a3f651 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -1781,6 +1781,7 @@ F:	drivers/i2c/busses/i2c-pasemi-core.c
>>  F:	drivers/i2c/busses/i2c-pasemi-platform.c
>>  F:	drivers/irqchip/irq-apple-aic.c
>>  F:	drivers/mailbox/apple-mailbox.c
>> +F:	drivers/nvmem/apple-efuses.c
>>  F:	drivers/pinctrl/pinctrl-apple-gpio.c
>>  F:	drivers/soc/apple/*
>>  F:	drivers/watchdog/apple_wdt.c
>> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
>> index da414617a54d..bba29d1aec96 100644
>> --- a/drivers/nvmem/Kconfig
>> +++ b/drivers/nvmem/Kconfig
>> @@ -300,4 +300,16 @@ config NVMEM_BRCM_NVRAM
>>  	  This driver provides support for Broadcom's NVRAM that can be accessed
>>  	  using I/O mapping.
>>  
>> +config NVMEM_APPLE_EFUSES
>> +	tristate "Apple eFuse support"
>> +	depends on ARCH_APPLE || COMPILE_TEST
>> +	default ARCH_APPLE
>> +	help
>> +	  Say y here to enable support for reading eFuses on Apple SoCs
>> +	  such as the M1. These are e.g. used to store factory programmed
>> +	  calibration data required for the PCIe or the USB-C PHY.
>> +
>> +	  This driver can also be built as a module. If so, the module will
>> +	  be called nvmem-apple-efuses.
>> +
>>  endif
>> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
>> index dcbbde35b6a8..1a8e54691d3e 100644
>> --- a/drivers/nvmem/Makefile
>> +++ b/drivers/nvmem/Makefile
>> @@ -61,3 +61,5 @@ obj-$(CONFIG_NVMEM_RMEM) 	+= nvmem-rmem.o
>>  nvmem-rmem-y			:= rmem.o
>>  obj-$(CONFIG_NVMEM_BRCM_NVRAM)	+= nvmem_brcm_nvram.o
>>  nvmem_brcm_nvram-y		:= brcm_nvram.o
>> +obj-$(CONFIG_NVMEM_APPLE_EFUSES)	+= nvmem-apple-efuses.o
>> +nvmem-apple-efuses-y 		:= apple-efuses.o
>> diff --git a/drivers/nvmem/apple-efuses.c b/drivers/nvmem/apple-efuses.c
>> new file mode 100644
>> index 000000000000..dd5576ec5408
>> --- /dev/null
>> +++ b/drivers/nvmem/apple-efuses.c
>> @@ -0,0 +1,82 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Apple SoC eFuse driver
>> + *
>> + * Copyright (C) The Asahi Linux Contributors
>> + */
>> +
>> +#include <linux/io.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/module.h>
>> +#include <linux/nvmem-provider.h>
>> +#include <linux/platform_device.h>
>> +
>> +struct apple_efuses_priv {
>> +	void __iomem *fuses;
>> +};
>> +
>> +static int apple_efuses_read(void *context, unsigned int offset, void *val,
>> +			     size_t bytes)
>> +{
>> +	struct apple_efuses_priv *priv = context;
>> +	u32 *dst = val;
>> +
>> +	while (bytes >= sizeof(u32)) {
>> +		*dst++ = readl_relaxed(priv->fuses + offset);
>> +		bytes -= sizeof(u32);
>> +		offset += sizeof(u32);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int apple_efuses_probe(struct platform_device *pdev)
>> +{
>> +	struct apple_efuses_priv *priv;
>> +	struct resource *res;
>> +	struct nvmem_config config = {
>> +		.dev = &pdev->dev,
>> +		.read_only = true,
>> +		.reg_read = apple_efuses_read,
>> +		.stride = sizeof(u32),
>> +		.word_size = sizeof(u32),
>> +		.name = "apple_efuses_nvmem",
>> +		.id = NVMEM_DEVID_AUTO,
>> +		.owner = THIS_MODULE,
>> +		.root_only = true,
>> +	};
>> +
>> +	priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
>> +	if (IS_ERR(priv->fuses))
>> +		return PTR_ERR(priv->fuses);
>> +
>> +	config.priv = priv;
>> +	config.size = resource_size(res);
>> +
>> +	return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
>> +}
>> +
>> +static const struct of_device_id apple_efuses_of_match[] = {
>> +	{ .compatible = "apple,efuses", },
>> +	{}
>> +};
>> +
>> +MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
>> +
>> +static struct platform_driver apple_efuses_driver = {
>> +	.driver = {
>> +		.name = "apple_efuses",
>> +		.of_match_table = apple_efuses_of_match,
>> +		.owner = THIS_MODULE,
>
> You wrote it also in changelog, but why do you need it? Doesn't core set
> it? Coccinelle should complain about this as well.
>

yeah, you're right. I shouldn't have just blindly followed what Hector and Joey
had to do for another subsystem to make reference counting work there.

I just checked again and it's neither required here not in struct nvmem_config
because module_platform_driver -> platform_driver_register ->
__platform_driver_register will set it in struct platform_driver and the
nvmem core will take it from there and set it inside nvmem_config.


thanks,


Sven