soc: renesas: Add SYSC driver for Renesas RZ family

The RZ/G3S system controller (SYSC) has various registers that control
different functionalities.  One of the exposed register offers
information about the SoC identification.

Add a driver that identifies the SoC.  Later the driver will be extended
with other functionalities.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250128031342.52675-2-john.madieu.xa@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

drivers/soc/renesas/Kconfig

@@ -383,4 +383,7 @@ config PWC_RZV2M
 config RST_RCAR
 	bool "Reset Controller support for R-Car" if COMPILE_TEST
 
+config SYSC_RZ
+	bool "System controller for RZ SoCs" if COMPILE_TEST
+
 endif # SOC_RENESAS

drivers/soc/renesas/Makefile

@@ -10,3 +10,4 @@ endif
 # Family
 obj-$(CONFIG_PWC_RZV2M)		+= pwc-rzv2m.o
 obj-$(CONFIG_RST_RCAR)		+= rcar-rst.o
+obj-$(CONFIG_SYSC_RZ)		+= rz-sysc.o

drivers/soc/renesas/rz-sysc.c

@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RZ System controller driver
+ *
+ * Copyright (C) 2024 Renesas Electronics Corp.
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/sys_soc.h>
+
+#include "rz-sysc.h"
+
+#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
+
+/**
+ * struct rz_sysc - RZ SYSC private data structure
+ * @base: SYSC base address
+ * @dev: SYSC device pointer
+ */
+struct rz_sysc {
+	void __iomem *base;
+	struct device *dev;
+};
+
+static int rz_sysc_soc_init(struct rz_sysc *sysc, const struct of_device_id *match)
+{
+	const struct rz_sysc_init_data *sysc_data = match->data;
+	const struct rz_sysc_soc_id_init_data *soc_data = sysc_data->soc_id_init_data;
+	struct soc_device_attribute *soc_dev_attr;
+	const char *soc_id_start, *soc_id_end;
+	u32 val, revision, specific_id;
+	struct soc_device *soc_dev;
+	char soc_id[32] = {0};
+	size_t size;
+
+	soc_id_start = strchr(match->compatible, ',') + 1;
+	soc_id_end = strchr(match->compatible, '-');
+	size = soc_id_end - soc_id_start + 1;
+	if (size > 32)
+		size = sizeof(soc_id);
+	strscpy(soc_id, soc_id_start, size);
+
+	soc_dev_attr = devm_kzalloc(sysc->dev, sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	soc_dev_attr->family = devm_kstrdup(sysc->dev, soc_data->family, GFP_KERNEL);
+	if (!soc_dev_attr->family)
+		return -ENOMEM;
+
+	soc_dev_attr->soc_id = devm_kstrdup(sysc->dev, soc_id, GFP_KERNEL);
+	if (!soc_dev_attr->soc_id)
+		return -ENOMEM;
+
+	val = readl(sysc->base + soc_data->devid_offset);
+	revision = field_get(soc_data->revision_mask, val);
+	specific_id = field_get(soc_data->specific_id_mask, val);
+	soc_dev_attr->revision = devm_kasprintf(sysc->dev, GFP_KERNEL, "%u", revision);
+	if (!soc_dev_attr->revision)
+		return -ENOMEM;
+
+	if (soc_data->id && specific_id != soc_data->id) {
+		dev_warn(sysc->dev, "SoC mismatch (product = 0x%x)\n", specific_id);
+		return -ENODEV;
+	}
+
+	dev_info(sysc->dev, "Detected Renesas %s %s Rev %s\n", soc_dev_attr->family,
+		 soc_dev_attr->soc_id, soc_dev_attr->revision);
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev))
+		return PTR_ERR(soc_dev);
+
+	return 0;
+}
+
+static const struct of_device_id rz_sysc_match[] = {
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rz_sysc_match);
+
+static int rz_sysc_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+	struct device *dev = &pdev->dev;
+	struct rz_sysc *sysc;
+
+	match = of_match_node(rz_sysc_match, dev->of_node);
+	if (!match)
+		return -ENODEV;
+
+	sysc = devm_kzalloc(dev, sizeof(*sysc), GFP_KERNEL);
+	if (!sysc)
+		return -ENOMEM;
+
+	sysc->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(sysc->base))
+		return PTR_ERR(sysc->base);
+
+	sysc->dev = dev;
+	return rz_sysc_soc_init(sysc, match);
+}
+
+static struct platform_driver rz_sysc_driver = {
+	.driver = {
+		.name = "renesas-rz-sysc",
+		.suppress_bind_attrs = true,
+		.of_match_table = rz_sysc_match
+	},
+	.probe = rz_sysc_probe
+};
+
+static int __init rz_sysc_init(void)
+{
+	return platform_driver_register(&rz_sysc_driver);
+}
+subsys_initcall(rz_sysc_init);
+
+MODULE_DESCRIPTION("Renesas RZ System Controller Driver");
+MODULE_AUTHOR("Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>");
+MODULE_LICENSE("GPL");

drivers/soc/renesas/rz-sysc.h

@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Renesas RZ System Controller
+ *
+ * Copyright (C) 2024 Renesas Electronics Corp.
+ */
+
+#ifndef __SOC_RENESAS_RZ_SYSC_H__
+#define __SOC_RENESAS_RZ_SYSC_H__
+
+#include <linux/types.h>
+
+/**
+ * struct rz_syc_soc_id_init_data - RZ SYSC SoC identification initialization data
+ * @family: RZ SoC family
+ * @id: RZ SoC expected ID
+ * @devid_offset: SYSC SoC ID register offset
+ * @revision_mask: SYSC SoC ID revision mask
+ * @specific_id_mask: SYSC SoC ID specific ID mask
+ */
+struct rz_sysc_soc_id_init_data {
+	const char * const family;
+	u32 id;
+	u32 devid_offset;
+	u32 revision_mask;
+	u32 specific_id_mask;
+};
+
+/**
+ * struct rz_sysc_init_data - RZ SYSC initialization data
+ * @soc_id_init_data: RZ SYSC SoC ID initialization data
+ */
+struct rz_sysc_init_data {
+	const struct rz_sysc_soc_id_init_data *soc_id_init_data;
+};
+
+#endif /* __SOC_RENESAS_RZ_SYSC_H__ */