[v5,1/2] soc: loongson: add GUTS driver for loongson-2 platforms

diff --git a/MAINTAINERS b/MAINTAINERS
index c9dc5ddbd9fe..20ce056ae207 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12041,6 +12041,12 @@  S:	Maintained
 F:	Documentation/devicetree/bindings/pinctrl/loongson,ls2k-pinctrl.yaml
 F:	drivers/pinctrl/pinctrl-loongson2.c
 
+LOONGSON-2 SOC SERIES GUTS DRIVER
+M:	Yinbo Zhu <zhuyinbo@loongson.cn>
+L:	loongarch@lists.linux.dev
+S:	Maintained
+F:	drivers/soc/loongson/loongson2_guts.c
+
 LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI)
 M:	Sathya Prakash <sathya.prakash@broadcom.com>
 M:	Sreekanth Reddy <sreekanth.reddy@broadcom.com>
diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
index e461c071189b..5dbb09f843f7 100644
--- a/drivers/soc/Kconfig
+++ b/drivers/soc/Kconfig
@@ -13,6 +13,7 @@  source "drivers/soc/fujitsu/Kconfig"
 source "drivers/soc/imx/Kconfig"
 source "drivers/soc/ixp4xx/Kconfig"
 source "drivers/soc/litex/Kconfig"
+source "drivers/soc/loongson/Kconfig"
 source "drivers/soc/mediatek/Kconfig"
 source "drivers/soc/microchip/Kconfig"
 source "drivers/soc/pxa/Kconfig"
diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
index 69ba6508cf2c..fff513bd522d 100644
--- a/drivers/soc/Makefile
+++ b/drivers/soc/Makefile
@@ -18,6 +18,7 @@  obj-y				+= imx/
 obj-y				+= ixp4xx/
 obj-$(CONFIG_SOC_XWAY)		+= lantiq/
 obj-$(CONFIG_LITEX_SOC_CONTROLLER) += litex/
+obj-y				+= loongson/
 obj-y				+= mediatek/
 obj-y				+= microchip/
 obj-y				+= pxa/
diff --git a/drivers/soc/loongson/Kconfig b/drivers/soc/loongson/Kconfig
new file mode 100644
index 000000000000..c60119b9d247
--- /dev/null
+++ b/drivers/soc/loongson/Kconfig
@@ -0,0 +1,18 @@ 
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Loongson-2 series SoC drivers
+#
+
+config LOONGSON2_GUTS
+	tristate "Loongson-2 GUTS"
+	depends on LOONGARCH || COMPILE_TEST
+	select SOC_BUS
+	help
+	  The global utilities block controls PCIE device enabling, alternate
+	  function selection for multiplexed signals, consistency of HDA, USB
+	  and PCIE, configuration of memory controller, rtc controller, lio
+	  controller, and clock control. This patch adds a driver to manage
+	  and access global utilities block for loongarch architecture Loongson-2
+	  SoCs. Initially only reading SVR and registering soc device are
+	  supported. Other guts accesses, such as reading PMON configuration by
+	  default, should eventually be added into this driver as well.
diff --git a/drivers/soc/loongson/Makefile b/drivers/soc/loongson/Makefile
new file mode 100644
index 000000000000..263c486df638
--- /dev/null
+++ b/drivers/soc/loongson/Makefile
@@ -0,0 +1,6 @@ 
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Makefile for the Linux Kernel SoC Loongson-2 specific device drivers
+#
+
+obj-$(CONFIG_LOONGSON2_GUTS)		+= loongson2_guts.o
diff --git a/drivers/soc/loongson/loongson2_guts.c b/drivers/soc/loongson/loongson2_guts.c
new file mode 100644
index 000000000000..8f3d5465c7e8
--- /dev/null
+++ b/drivers/soc/loongson/loongson2_guts.c
@@ -0,0 +1,189 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Author: Yinbo Zhu <zhuyinbo@loongson.cn>
+ * Copyright (C) 2022-2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/of_fdt.h>
+#include <linux/sys_soc.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+static struct soc_device_attribute soc_dev_attr;
+static struct soc_device *soc_dev;
+
+/*
+ * Global Utility Registers.
+ *
+ * Not all registers defined in this structure are available on all chips, so
+ * you are expected to know whether a given register actually exists on your
+ * chip before you access it.
+ *
+ * Also, some registers are similar on different chips but have slightly
+ * different names.  In these cases, one name is chosen to avoid extraneous
+ * #ifdefs.
+ */
+struct scfg_guts {
+	u32     svr;            /* Version Register */
+	u8      res0[4];
+	u16     feature;        /* Feature Register */
+	u32     vendor;         /* Vendor Register */
+	u8      res1[6];
+	u32     id;
+	u8      res2[0x3ff8 - 0x18];
+	u32     chip;
+};
+
+static struct guts {
+	struct scfg_guts __iomem *regs;
+	bool little_endian;
+} *guts;
+
+struct loongson2_soc_die_attr {
+	char	*die;
+	u32	svr;
+	u32	mask;
+};
+
+/* SoC die attribute definition for Loongson-2 platform */
+static const struct loongson2_soc_die_attr loongson2_soc_die[] = {
+
+	/*
+	 * LA-based SoCs Loongson-2 Series
+	 */
+
+	/* Die: 2k1000la, SoC: 2k1000la */
+	{ .die		= "2K1000LA",
+	  .svr		= 0x00000013,
+	  .mask		= 0x000000ff,
+	},
+	{ },
+};
+
+static const struct loongson2_soc_die_attr *loongson2_soc_die_match(
+	u32 svr, const struct loongson2_soc_die_attr *matches)
+{
+	while (matches->svr) {
+		if (matches->svr == (svr & matches->mask))
+			return matches;
+		matches++;
+	};
+
+	return NULL;
+}
+
+static u32 loongson2_guts_get_svr(void)
+{
+	u32 svr = 0;
+
+	if (!guts || !guts->regs)
+		return svr;
+
+	if (guts->little_endian)
+		svr = ioread32(&guts->regs->svr);
+	else
+		svr = ioread32be(&guts->regs->svr);
+
+	return svr;
+}
+
+static int loongson2_guts_probe(struct platform_device *pdev)
+{
+	struct device_node *root, *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	const struct loongson2_soc_die_attr *soc_die;
+	const char *machine;
+	u32 svr;
+
+	/* Initialize guts */
+	guts = devm_kzalloc(dev, sizeof(*guts), GFP_KERNEL);
+	if (!guts)
+		return -ENOMEM;
+
+	guts->little_endian = of_property_read_bool(np, "little-endian");
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	guts->regs = ioremap(res->start, res->end - res->start + 1);
+	if (IS_ERR(guts->regs))
+		return PTR_ERR(guts->regs);
+
+	/* Register soc device */
+	root = of_find_node_by_path("/");
+	if (of_property_read_string(root, "model", &machine))
+		of_property_read_string_index(root, "compatible", 0, &machine);
+	of_node_put(root);
+	if (machine)
+		soc_dev_attr.machine = devm_kstrdup(dev, machine, GFP_KERNEL);
+
+	svr = loongson2_guts_get_svr();
+	soc_die = loongson2_soc_die_match(svr, loongson2_soc_die);
+	if (soc_die) {
+		soc_dev_attr.family = devm_kasprintf(dev, GFP_KERNEL,
+						     "Loongson %s", soc_die->die);
+	} else {
+		soc_dev_attr.family = devm_kasprintf(dev, GFP_KERNEL, "Loongson");
+	}
+	if (!soc_dev_attr.family)
+		return -ENOMEM;
+	soc_dev_attr.soc_id = devm_kasprintf(dev, GFP_KERNEL,
+					     "svr:0x%08x", svr);
+	if (!soc_dev_attr.soc_id)
+		return -ENOMEM;
+	soc_dev_attr.revision = devm_kasprintf(dev, GFP_KERNEL, "%d.%d",
+					       (svr >>  4) & 0xf, svr & 0xf);
+	if (!soc_dev_attr.revision)
+		return -ENOMEM;
+
+	soc_dev = soc_device_register(&soc_dev_attr);
+	if (IS_ERR(soc_dev))
+		return PTR_ERR(soc_dev);
+
+	pr_info("Machine: %s\n", soc_dev_attr.machine);
+	pr_info("SoC family: %s\n", soc_dev_attr.family);
+	pr_info("SoC ID: %s, Revision: %s\n",
+		soc_dev_attr.soc_id, soc_dev_attr.revision);
+
+	return 0;
+}
+
+static int loongson2_guts_remove(struct platform_device *dev)
+{
+	soc_device_unregister(soc_dev);
+
+	return 0;
+}
+
+/*
+ * Table for matching compatible strings, for device tree
+ * guts node, for Loongson-2 SoCs.
+ */
+static const struct of_device_id loongson2_guts_of_match[] = {
+	{ .compatible = "loongson,ls2k-chipid", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, loongson2_guts_of_match);
+
+static struct platform_driver loongson2_guts_driver = {
+	.driver = {
+		.name = "loongson2-guts",
+		.of_match_table = loongson2_guts_of_match,
+	},
+	.probe = loongson2_guts_probe,
+	.remove = loongson2_guts_remove,
+};
+
+static int __init loongson2_guts_init(void)
+{
+	return platform_driver_register(&loongson2_guts_driver);
+}
+core_initcall(loongson2_guts_init);
+
+static void __exit loongson2_guts_exit(void)
+{
+	platform_driver_unregister(&loongson2_guts_driver);
+}
+module_exit(loongson2_guts_exit);