[PATCH v2 2/3] nvmem: Add spmi-nvmem driver

[Sasha Finkelstein via B4 Relay <devnull+fnkl.kernel.gmail.com@kernel.org>]

From: Hector Martin <marcan@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.

Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Hector Martin <marcan@marcan.st>
Co-developed-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
---
 MAINTAINERS                |  1 +
 drivers/nvmem/Kconfig      | 13 ++++++++++
 drivers/nvmem/Makefile     |  2 ++
 drivers/nvmem/spmi-nvmem.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 78 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..c25c599fc79648e890ccc4e003224c9a218f393f 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -310,6 +310,19 @@ 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"
+	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@marcan.st>");
+MODULE_DESCRIPTION("SPMI NVMEM driver");

-- 
2.49.0