[PATCH 2/3] nvmem: Add spmi-nvmem driver

[Srinivas Kandagatla]

On 15/04/2025 22:52, Sasha Finkelstein via B4 Relay wrote:
> From: Hector Martin <marcan at marcan.st>
> 
> This driver exposes a SPMI device as an NVMEM device.
> It is intended to be used with e.g. PMUs/PMICs that are used to
> hold power management configuration, such as used on Apple Silicon
> Macs.
> 
> Signed-off-by: Hector Martin <marcan at marcan.st>
> Signed-off-by: Sasha Finkelstein <fnkl.kernel at gmail.com>
> ---
>   MAINTAINERS                |  1 +
>   drivers/nvmem/Kconfig      | 14 +++++++++++
>   drivers/nvmem/Makefile     |  2 ++
>   drivers/nvmem/spmi-nvmem.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 79 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e7b2d0df81b387ba5398957131971588dc7b89dc..63c12f901aed1f3e6de8227d6db34af1bd046fe6 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2298,6 +2298,7 @@ F:	drivers/iommu/io-pgtable-dart.c
>   F:	drivers/irqchip/irq-apple-aic.c
>   F:	drivers/nvme/host/apple.c
>   F:	drivers/nvmem/apple-efuses.c
> +F:	drivers/nvmem/spmi-nvmem.c
>   F:	drivers/pinctrl/pinctrl-apple-gpio.c
>   F:	drivers/pwm/pwm-apple.c
>   F:	drivers/soc/apple/*
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 8671b7c974b933e147154bb40b5d41b5730518d2..9ec907d8aa6ef7df0ea45cc35e92d8239d2705ee 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -310,6 +310,20 @@ config NVMEM_SNVS_LPGPR
>   	  This driver can also be built as a module. If so, the module
>   	  will be called nvmem-snvs-lpgpr.
>   
> +config NVMEM_SPMI
> +	tristate "Generic SPMI NVMEM"
> +	default ARCH_APPLE
Why default is set to ARCH_APPLE?

This will endup with y in arm64 defconfig, means increasing the size of 
kernel.

should it be:

depends on ARCH_APPLE || COMPILE_TEST


--srini
> +	depends on SPMI
> +	select REGMAP_SPMI
> +	help
> +	  Say y here to build a generic driver to expose a SPMI device
> +	  as a NVMEM provider. This can be used for PMIC/PMU devices which
> +	  are used to store power and RTC-related settings on certain
> +	  platforms, such as Apple Silicon Macs.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called nvmem-spmi.
> +
>   config NVMEM_SPMI_SDAM
>   	tristate "SPMI SDAM Support"
>   	depends on SPMI
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index 5b77bbb6488bf89bfb305750a1cbf4a6731a0a58..b639f4284184db026bb27b11e04d54b8f7ff166f 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -64,6 +64,8 @@ obj-$(CONFIG_NVMEM_SC27XX_EFUSE)	+= nvmem-sc27xx-efuse.o
>   nvmem-sc27xx-efuse-y			:= sc27xx-efuse.o
>   obj-$(CONFIG_NVMEM_SNVS_LPGPR)		+= nvmem_snvs_lpgpr.o
>   nvmem_snvs_lpgpr-y			:= snvs_lpgpr.o
> +obj-$(CONFIG_NVMEM_SPMI)		+= nvmem_spmi.o
> +nvmem_spmi-y				:= spmi-nvmem.o
>   obj-$(CONFIG_NVMEM_SPMI_SDAM)		+= nvmem_qcom-spmi-sdam.o
>   nvmem_qcom-spmi-sdam-y			+= qcom-spmi-sdam.o
>   obj-$(CONFIG_NVMEM_SPRD_EFUSE)		+= nvmem_sprd_efuse.o
> diff --git a/drivers/nvmem/spmi-nvmem.c b/drivers/nvmem/spmi-nvmem.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..fff6162cb22dd7ab45883f004f5b63ebae014698
> --- /dev/null
> +++ b/drivers/nvmem/spmi-nvmem.c
> @@ -0,0 +1,62 @@
> +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> +/*
> + * Generic SPMI NVMEM driver
> + *
> + * Copyright The Asahi Linux Contributors
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/nvmem-provider.h>
> +#include <linux/of.h>
> +#include <linux/spmi.h>
> +#include <linux/regmap.h>
> +
> +static const struct regmap_config spmi_regmap_config = {
> +	.reg_bits	= 16,
> +	.val_bits	= 8,
> +	.max_register	= 0xffff,
> +};
> +
> +static int spmi_nvmem_probe(struct spmi_device *sdev)
> +{
> +	struct regmap *regmap;
> +	struct nvmem_config nvmem_cfg = {
> +		.dev = &sdev->dev,
> +		.name = "spmi_nvmem",
> +		.id = NVMEM_DEVID_AUTO,
> +		.word_size = 1,
> +		.stride = 1,
> +		.size = 0xffff,
> +		.reg_read = (void *)regmap_bulk_read,
> +		.reg_write = (void *)regmap_bulk_write,
> +	};
> +
> +	regmap = devm_regmap_init_spmi_ext(sdev, &spmi_regmap_config);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	nvmem_cfg.priv = regmap;
> +
> +	return PTR_ERR_OR_ZERO(devm_nvmem_register(&sdev->dev, &nvmem_cfg));
> +}
> +
> +static const struct of_device_id spmi_nvmem_id_table[] = {
> +	{ .compatible = "spmi-nvmem" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, spmi_nvmem_id_table);
> +
> +static struct spmi_driver spmi_nvmem_driver = {
> +	.probe = spmi_nvmem_probe,
> +	.driver = {
> +		.name = "spmi-nvmem",
> +		.of_match_table	= spmi_nvmem_id_table,
> +	},
> +};
> +
> +module_spmi_driver(spmi_nvmem_driver);
> +
> +MODULE_LICENSE("Dual MIT/GPL");
> +MODULE_AUTHOR("Hector Martin <marcan at marcan.st>");
> +MODULE_DESCRIPTION("SPMI NVMEM driver");
>