mfd: Add a simple-mfd-spmi driver

This is the SPMI counterpart to simple-mfd-i2c. It merely exposes the
SPMI register address space as an MFD device, such that different
aspects of a device can be managed by separate drivers.

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

drivers/mfd/Kconfig

@@ -52,6 +52,21 @@ config MFD_ACT8945A
 	  linear regulators, along with a complete ActivePath battery
 	  charger.
 
+config MFD_APPLE_SPMI_PMU
+	tristate "Apple SPMI PMUs"
+	depends on SPMI
+	depends on ARCH_APPLE || COMPILE_TEST
+	default ARCH_APPLE
+	select MFD_SIMPLE_MFD_SPMI
+	help
+	  Say yes here to enable support for Apple PMUs attached via the
+	  SPMI bus. These can be found on Apple devices such as Apple
+	  Silicon Macs.
+
+	  This driver itself only attaches to the core device, and relies
+	  on subsystem drivers for individual device functions. You must
+	  enable those for it to be useful.
+
 config MFD_SUN4I_GPADC
 	tristate "Allwinner sunxi platforms' GPADC MFD driver"
 	select MFD_CORE
@@ -1312,6 +1327,19 @@ config MFD_SIMPLE_MFD_I2C
 	  sub-devices represented by child nodes in Device Tree will be
 	  subsequently registered.
 
+config MFD_SIMPLE_MFD_SPMI
+	tristate
+	depends on SPMI
+	select MFD_CORE
+	select REGMAP_SPMI
+	help
+	  This driver creates a single register map with the intention for it
+	  to be shared by all sub-devices.
+
+	  Once the register map has been successfully initialised, any
+	  sub-devices represented by child nodes in Device Tree will be
+	  subsequently registered.
+
 config MFD_SL28CPLD
 	tristate "Kontron sl28cpld Board Management Controller"
 	depends on I2C

drivers/mfd/Makefile

@@ -271,6 +271,7 @@ obj-$(CONFIG_MFD_QCOM_PM8008)	+= qcom-pm8008.o
 
 obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o
 obj-$(CONFIG_MFD_SIMPLE_MFD_I2C)	+= simple-mfd-i2c.o
+obj-$(CONFIG_MFD_SIMPLE_MFD_SPMI)	+= simple-mfd-spmi.o
 obj-$(CONFIG_MFD_SMPRO)		+= smpro-core.o
 
 obj-$(CONFIG_MFD_INTEL_M10_BMC_CORE)   += intel-m10-bmc-core.o

drivers/mfd/simple-mfd-spmi.c

@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Simple MFD - SPMI
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spmi.h>
+#include <linux/of_platform.h>
+
+static const struct regmap_config spmi_regmap_config = {
+	.reg_bits	= 16,
+	.val_bits	= 8,
+	.max_register	= 0xffff,
+};
+
+static int simple_spmi_probe(struct spmi_device *sdev)
+{
+	struct regmap *regmap;
+
+	regmap = devm_regmap_init_spmi_ext(sdev, &spmi_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	return devm_of_platform_populate(&sdev->dev);
+}
+
+static const struct of_device_id simple_spmi_id_table[] = {
+	{ .compatible = "apple,spmi-pmu" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, simple_spmi_id_table);
+
+static struct spmi_driver pmic_spmi_driver = {
+	.probe = simple_spmi_probe,
+	.driver = {
+		.name = "simple-mfd-spmi",
+		.owner = THIS_MODULE,
+		.of_match_table = simple_spmi_id_table,
+	},
+};
+module_spmi_driver(pmic_spmi_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Simple MFD - SPMI driver");
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");