mfd: altera-sysmgr: Add SOCFPGA System Manager

The SOCFPGA System Manager register block aggregates different
peripheral functions into one area.
On 32 bit ARM parts, handle in the same way as syscon.
On 64 bit ARM parts, the System Manager can only be accessed by
EL3 secure mode. Since a SMC call to EL3 is required, this new
driver uses regmaps similar to syscon to handle the SMC call.

Since regmaps abstract out the underlying register access, the
changes to drivers accessing the System Manager are minimal.

Signed-off-by: Thor Thayer <[e-mail]>
Reviewed-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

MAINTAINERS

···
 S:	Maintained
 F:	drivers/gpio/gpio-altera.c
 
+ALTERA SYSTEM MANAGER DRIVER
+M:	Thor Thayer <[e-mail]>
+S:	Maintained
+F:	drivers/mfd/altera-sysmgr.c
+F:	include/linux/mfd/altera-sysgmr.h
+
 ALTERA SYSTEM RESOURCE DRIVER FOR ARRIA10 DEVKIT
 M:	Thor Thayer <[e-mail]>
 S:	Maintained

drivers/mfd/Kconfig

···
 	  accessing the external gpio extender (LEDs & buttons) and
 	  power supply alarms (hwmon).
 
+config MFD_ALTERA_SYSMGR
+	bool "Altera SOCFPGA System Manager"
+	depends on (ARCH_SOCFPGA || ARCH_STRATIX10) && OF
+	select MFD_SYSCON
+	help
+	  Select this to get System Manager support for all Altera branded
+	  SOCFPGAs. The SOCFPGA System Manager handles all SOCFPGAs by
+	  using regmap_mmio accesses for ARM32 parts and SMC calls to
+	  EL3 for ARM64 parts.
+
 config MFD_ACT8945A
 	tristate "Active-semi ACT8945A"
 	select MFD_CORE

drivers/mfd/Makefile

···
 obj-$(CONFIG_MFD_MT6397)	+= mt6397-core.o
 
 obj-$(CONFIG_MFD_ALTERA_A10SR)	+= altera-a10sr.o
+obj-$(CONFIG_MFD_ALTERA_SYSMGR) += altera-sysmgr.o
 obj-$(CONFIG_MFD_STPMIC1)	+= stpmic1.o
 obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-gpadc.o
 

drivers/mfd/altera-sysmgr.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2018-2019, Intel Corporation.
+ *  Copyright (C) 2012 Freescale Semiconductor, Inc.
+ *  Copyright (C) 2012 Linaro Ltd.
+ *
+ *  Based on syscon driver.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/mfd/altera-sysmgr.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/**
+ * struct altr_sysmgr - Altera SOCFPGA System Manager
+ * @regmap: the regmap used for System Manager accesses.
+ * @base  : the base address for the System Manager
+ */
+struct altr_sysmgr {
+	struct regmap   *regmap;
+	resource_size_t *base;
+};
+
+static struct platform_driver altr_sysmgr_driver;
+
+/**
+ * s10_protected_reg_write
+ * Write to a protected SMC register.
+ * @base: Base address of System Manager
+ * @reg:  Address offset of register
+ * @val:  Value to write
+ * Return: INTEL_SIP_SMC_STATUS_OK (0) on success
+ *	   INTEL_SIP_SMC_REG_ERROR on error
+ *	   INTEL_SIP_SMC_RETURN_UNKNOWN_FUNCTION if not supported
+ */
+static int s10_protected_reg_write(void *base,
+				   unsigned int reg, unsigned int val)
+{
+	struct arm_smccc_res result;
+	unsigned long sysmgr_base = (unsigned long)base;
+
+	arm_smccc_smc(INTEL_SIP_SMC_REG_WRITE, sysmgr_base + reg,
+		      val, 0, 0, 0, 0, 0, &result);
+
+	return (int)result.a0;
+}
+
+/**
+ * s10_protected_reg_read
+ * Read the status of a protected SMC register
+ * @base: Base address of System Manager.
+ * @reg:  Address of register
+ * @val:  Value read.
+ * Return: INTEL_SIP_SMC_STATUS_OK (0) on success
+ *	   INTEL_SIP_SMC_REG_ERROR on error
+ *	   INTEL_SIP_SMC_RETURN_UNKNOWN_FUNCTION if not supported
+ */
+static int s10_protected_reg_read(void *base,
+				  unsigned int reg, unsigned int *val)
+{
+	struct arm_smccc_res result;
+	unsigned long sysmgr_base = (unsigned long)base;
+
+	arm_smccc_smc(INTEL_SIP_SMC_REG_READ, sysmgr_base + reg,
+		      0, 0, 0, 0, 0, 0, &result);
+
+	*val = (unsigned int)result.a1;
+
+	return (int)result.a0;
+}
+
+static struct regmap_config altr_sysmgr_regmap_cfg = {
+	.name = "altr_sysmgr",
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.fast_io = true,
+	.use_single_read = true,
+	.use_single_write = true,
+};
+
+/**
+ * sysmgr_match_phandle
+ * Matching function used by driver_find_device().
+ * Return: True if match is found, otherwise false.
+ */
+static int sysmgr_match_phandle(struct device *dev, void *data)
+{
+	return dev->of_node == (struct device_node *)data;
+}
+
+/**
+ * altr_sysmgr_regmap_lookup_by_phandle
+ * Find the sysmgr previous configured in probe() and return regmap property.
+ * Return: regmap if found or error if not found.
+ */
+struct regmap *altr_sysmgr_regmap_lookup_by_phandle(struct device_node *np,
+						    const char *property)
+{
+	struct device *dev;
+	struct altr_sysmgr *sysmgr;
+	struct device_node *sysmgr_np;
+
+	if (property)
+		sysmgr_np = of_parse_phandle(np, property, 0);
+	else
+		sysmgr_np = np;
+
+	if (!sysmgr_np)
+		return ERR_PTR(-ENODEV);
+
+	dev = driver_find_device(&altr_sysmgr_driver.driver, NULL,
+				 (void *)sysmgr_np, sysmgr_match_phandle);
+	of_node_put(sysmgr_np);
+	if (!dev)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	sysmgr = dev_get_drvdata(dev);
+
+	return sysmgr->regmap;
+}
+EXPORT_SYMBOL_GPL(altr_sysmgr_regmap_lookup_by_phandle);
+
+static int sysmgr_probe(struct platform_device *pdev)
+{
+	struct altr_sysmgr *sysmgr;
+	struct regmap *regmap;
+	struct resource *res;
+	struct regmap_config sysmgr_config = altr_sysmgr_regmap_cfg;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+
+	sysmgr = devm_kzalloc(dev, sizeof(*sysmgr), GFP_KERNEL);
+	if (!sysmgr)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOENT;
+
+	sysmgr_config.max_register = resource_size(res) -
+				     sysmgr_config.reg_stride;
+	if (of_device_is_compatible(np, "altr,sys-mgr-s10")) {
+		/* Need physical address for SMCC call */
+		sysmgr->base = (resource_size_t *)res->start;
+		sysmgr_config.reg_read = s10_protected_reg_read;
+		sysmgr_config.reg_write = s10_protected_reg_write;
+
+		regmap = devm_regmap_init(dev, NULL, sysmgr->base,
+					  &sysmgr_config);
+	} else {
+		sysmgr->base = devm_ioremap(dev, res->start,
+					    resource_size(res));
+		if (!sysmgr->base)
+			return -ENOMEM;
+
+		sysmgr_config.max_register = res->end - res->start - 3;
+		regmap = devm_regmap_init_mmio(dev, sysmgr->base,
+					       &sysmgr_config);
+	}
+
+	if (IS_ERR(regmap)) {
+		pr_err("regmap init failed\n");
+		return PTR_ERR(regmap);
+	}
+
+	sysmgr->regmap = regmap;
+
+	platform_set_drvdata(pdev, sysmgr);
+
+	return 0;
+}
+
+static const struct of_device_id altr_sysmgr_of_match[] = {
+	{ .compatible = "altr,sys-mgr" },
+	{ .compatible = "altr,sys-mgr-s10" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, altr_sysmgr_of_match);
+
+static struct platform_driver altr_sysmgr_driver = {
+	.probe =  sysmgr_probe,
+	.driver = {
+		.name = "altr,system_manager",
+		.of_match_table = altr_sysmgr_of_match,
+	},
+};
+
+static int __init altr_sysmgr_init(void)
+{
+	return platform_driver_register(&altr_sysmgr_driver);
+}
+core_initcall(altr_sysmgr_init);
+
+static void __exit altr_sysmgr_exit(void)
+{
+	platform_driver_unregister(&altr_sysmgr_driver);
+}
+module_exit(altr_sysmgr_exit);
+
+MODULE_AUTHOR("Thor Thayer <>");
+MODULE_DESCRIPTION("SOCFPGA System Manager driver");
+MODULE_LICENSE("GPL v2");

include/linux/mfd/altera-sysmgr.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018-2019 Intel Corporation
+ * Copyright (C) 2012 Freescale Semiconductor, Inc.
+ * Copyright (C) 2012 Linaro Ltd.
+ */
+
+#ifndef __LINUX_MFD_ALTERA_SYSMGR_H__
+#define __LINUX_MFD_ALTERA_SYSMGR_H__
+
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/firmware/intel/stratix10-smc.h>
+
+struct device_node;
+
+#ifdef CONFIG_MFD_ALTERA_SYSMGR
+struct regmap *altr_sysmgr_regmap_lookup_by_phandle(struct device_node *np,
+						    const char *property);
+#else
+static inline struct regmap *
+altr_sysmgr_regmap_lookup_by_phandle(struct device_node *np,
+				     const char *property)
+{
+	return ERR_PTR(-ENOTSUPP);
+}
+#endif
+
+#endif /* __LINUX_MFD_ALTERA_SYSMGR_H__ */