[PATCH v2 1/2] soc: loongson: add GUTS driver for loongson2 platforms

[Yinbo Zhu]

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 loongson2 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.

Signed-off-by: Yinbo Zhu <zhuyinbo@xxxxxxxxxxx>
---
Change in v2:
		1. Add architecture support commit log description.
		2. Add other guts accesses plan commit log description.
		3. Add "depends on LOONGARCH || COMPILE_TEST" for
		   LOONGSON2_GUTS in Kconfig.
		4. Move the scfg_guts to .c file from .h and delete .h.
		5. Remove __packed on scfg_guts.

 MAINTAINERS                           |   6 +
 drivers/soc/Kconfig                   |   1 +
 drivers/soc/Makefile                  |   1 +
 drivers/soc/loongson/Kconfig          |  20 +++
 drivers/soc/loongson/Makefile         |   6 +
 drivers/soc/loongson/loongson2_guts.c | 189 ++++++++++++++++++++++++++
 6 files changed, 223 insertions(+)
 create mode 100644 drivers/soc/loongson/Kconfig
 create mode 100644 drivers/soc/loongson/Makefile
 create mode 100644 drivers/soc/loongson/loongson2_guts.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 2d002509fc65..0f06dc83f7c6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11930,6 +11930,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/pinctrl/loongson,ls2k-pinctrl.yaml
 F:	drivers/pinctrl/pinctrl-loongson2.c
 
+LOONGSON2 SOC SERIES GUTS DRIVER
+M:	Yinbo Zhu <zhuyinbo@xxxxxxxxxxx>
+L:	loongarch@xxxxxxxxxxxxxxx
+S:	Maintained
+F:	drivers/soc/loongson/loongson2_guts.c
+
 LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI)
 M:	Sathya Prakash <sathya.prakash@xxxxxxxxxxxx>
 M:	Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx>
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..04a4dd5192ef
--- /dev/null
+++ b/drivers/soc/loongson/Kconfig
@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Loongson2 series SoC drivers
+#
+
+menu "Loongson2 series SoC drivers"
+
+config LOONGSON2_GUTS
+	tristate "LOONGSON2 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 loongson2
+	  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..acfc90a624c9
--- /dev/null
+++ b/drivers/soc/loongson/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Makefile for the Linux Kernel SoC loongson2 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..15db9ebc3f14
--- /dev/null
+++ b/drivers/soc/loongson/loongson2_guts.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Author: Yinbo Zhu <zhuyinbo@xxxxxxxxxxx>
+ * 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 loongson2 platform */
+static const struct loongson2_soc_die_attr loongson2_soc_die[] = {
+
+	/*
+	 * LA-based SoCs Loongson2 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 Loongson2 SoCs.
+ */
+static const struct of_device_id loongson2_guts_of_match[] = {
+	{ .compatible = "loongson,ls2k-guts", },
+	{}
+};
+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);
-- 
2.31.1