[RFC,02/11] soc: Add Realtek chip info driver for RTD1195 and RTD1295

diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
index 833e04a7835c..06ae9d97321c 100644
--- a/drivers/soc/Kconfig
+++ b/drivers/soc/Kconfig
@@ -11,6 +11,7 @@  source "drivers/soc/imx/Kconfig"
 source "drivers/soc/ixp4xx/Kconfig"
 source "drivers/soc/mediatek/Kconfig"
 source "drivers/soc/qcom/Kconfig"
+source "drivers/soc/realtek/Kconfig"
 source "drivers/soc/renesas/Kconfig"
 source "drivers/soc/rockchip/Kconfig"
 source "drivers/soc/samsung/Kconfig"
diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
index 2ec355003524..1d55d838a342 100644
--- a/drivers/soc/Makefile
+++ b/drivers/soc/Makefile
@@ -17,6 +17,7 @@  obj-$(CONFIG_SOC_XWAY)		+= lantiq/
 obj-y				+= mediatek/
 obj-y				+= amlogic/
 obj-y				+= qcom/
+obj-y				+= realtek/
 obj-y				+= renesas/
 obj-$(CONFIG_ARCH_ROCKCHIP)	+= rockchip/
 obj-$(CONFIG_SOC_SAMSUNG)	+= samsung/
diff --git a/drivers/soc/realtek/Kconfig b/drivers/soc/realtek/Kconfig
new file mode 100644
index 000000000000..be75c1889c61
--- /dev/null
+++ b/drivers/soc/realtek/Kconfig
@@ -0,0 +1,13 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+if ARCH_REALTEK || COMPILE_TEST
+
+config REALTEK_SOC
+	tristate "Realtek chip info"
+	default ARCH_REALTEK
+	select SOC_BUS
+	help
+	  Say 'y' here to enable support for SoC info on Realtek RTD1195 and
+	  RTD1295 SoC families.
+	  If unsure, say 'n'.
+
+endif
diff --git a/drivers/soc/realtek/Makefile b/drivers/soc/realtek/Makefile
new file mode 100644
index 000000000000..49900273905b
--- /dev/null
+++ b/drivers/soc/realtek/Makefile
@@ -0,0 +1,2 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+obj-$(CONFIG_REALTEK_SOC) += chip.o
diff --git a/drivers/soc/realtek/chip.c b/drivers/soc/realtek/chip.c
new file mode 100644
index 000000000000..9d13422e9936
--- /dev/null
+++ b/drivers/soc/realtek/chip.c
@@ -0,0 +1,164 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Realtek System-on-Chip info
+ *
+ * Copyright (c) 2017-2019 Andreas Färber
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+
+#define REG_CHIP_ID	0x0
+#define REG_CHIP_REV	0x4
+
+struct rtd_soc_revision {
+	const char *name;
+	u32 chip_rev;
+};
+
+static const struct rtd_soc_revision rtd1195_revisions[] = {
+	{ "A", 0x00000000 },
+	{ "B", 0x00010000 },
+	{ "C", 0x00020000 },
+	{ "D", 0x00030000 },
+	{ }
+};
+
+static const struct rtd_soc_revision rtd1295_revisions[] = {
+	{ "A00", 0x00000000 },
+	{ "A01", 0x00010000 },
+	{ "B00", 0x00020000 },
+	{ "B01", 0x00030000 },
+	{ }
+};
+
+struct rtd_soc {
+	u32 chip_id;
+	const char *family;
+	const char *(*get_name)(struct device *dev, const struct rtd_soc *s);
+	const struct rtd_soc_revision *revisions;
+	const char *codename;
+};
+
+static const char *default_name(struct device *dev, const struct rtd_soc *s)
+{
+	return s->family;
+}
+
+static const struct rtd_soc rtd_soc_families[] = {
+	{ 0x00006329, "RTD1195", default_name, rtd1195_revisions, "Phoenix" },
+	{ 0x00006421, "RTD1295", default_name, rtd1295_revisions, "Kylin" },
+};
+
+static const struct rtd_soc *rtd_soc_by_chip_id(u32 chip_id)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(rtd_soc_families); i++) {
+		const struct rtd_soc *family = &rtd_soc_families[i];
+
+		if (family->chip_id == chip_id)
+			return family;
+	}
+	return NULL;
+}
+
+static const char *rtd_soc_rev(const struct rtd_soc *family, u32 chip_rev)
+{
+	if (family) {
+		const struct rtd_soc_revision *rev = family->revisions;
+
+		while (rev && rev->name) {
+			if (rev->chip_rev == chip_rev)
+				return rev->name;
+			rev++;
+		}
+	}
+	return "unknown";
+}
+
+static int rtd_soc_probe(struct platform_device *pdev)
+{
+	const struct rtd_soc *s;
+	struct soc_device_attribute *soc_dev_attr;
+	struct soc_device *soc_dev;
+	struct device_node *node;
+	void __iomem *base;
+	u32 chip_id, chip_rev;
+
+	base = of_iomap(pdev->dev.of_node, 0);
+	if (!base)
+		return -ENODEV;
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	chip_id  = readl_relaxed(base + REG_CHIP_ID);
+	chip_rev = readl_relaxed(base + REG_CHIP_REV);
+
+	node = of_find_node_by_path("/");
+	of_property_read_string(node, "model", &soc_dev_attr->machine);
+	of_node_put(node);
+
+	s = rtd_soc_by_chip_id(chip_id);
+
+	soc_dev_attr->family = kasprintf(GFP_KERNEL, "Realtek %s",
+		(s && s->codename) ? s->codename :
+		((s && s->family) ? s->family : "Digital Home Center"));
+
+	if (likely(s && s->get_name))
+		soc_dev_attr->soc_id = s->get_name(&pdev->dev, s);
+	else
+		soc_dev_attr->soc_id = "unknown";
+
+	soc_dev_attr->revision = rtd_soc_rev(s, chip_rev);
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr->family);
+		kfree(soc_dev_attr);
+		return PTR_ERR(soc_dev);
+	}
+
+	platform_set_drvdata(pdev, soc_dev);
+
+	dev_info(soc_device_to_device(soc_dev),
+		"%s %s (0x%08x) rev %s (0x%08x) detected\n",
+		soc_dev_attr->family, soc_dev_attr->soc_id, chip_id,
+		soc_dev_attr->revision, chip_rev);
+
+	return 0;
+}
+
+static int rtd_soc_remove(struct platform_device *pdev)
+{
+	struct soc_device *soc_dev = platform_get_drvdata(pdev);
+
+	soc_device_unregister(soc_dev);
+
+	return 0;
+}
+
+static const struct of_device_id rtd_soc_dt_ids[] = {
+	 { .compatible = "realtek,rtd1195-chip" },
+	 { }
+};
+
+static struct platform_driver rtd_soc_driver = {
+	.probe = rtd_soc_probe,
+	.remove = rtd_soc_remove,
+	.driver = {
+		.name = "rtd1195-soc",
+		.of_match_table	= rtd_soc_dt_ids,
+	},
+};
+module_platform_driver(rtd_soc_driver);
+
+MODULE_DESCRIPTION("Realtek SoC identification");
+MODULE_LICENSE("GPL");