Exynos SoCs have Chipid, for identification of product IDs and SoC revisions.
This patch intends to provide initialization code for all these functionalities,
at the same time it provides some sysfs entries for accessing these information
to user-space.

This driver uses existing binding for exynos-chipid.

CC: Grant Likely <redacted>
CC: Rob Herring <robh+dt@kernel.org>
CC: Linus Walleij <redacted>
Signed-off-by: Pankaj Dubey <redacted>
[m.szyprowski: for suggestion and code snippet of product_id_to_soc_id]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
 drivers/soc/samsung/Kconfig         |   5 ++
 drivers/soc/samsung/Makefile        |   1 +
 drivers/soc/samsung/exynos-chipid.c | 116 ++++++++++++++++++++++++++++++++++++
 3 files changed, 122 insertions(+)
 create mode 100644 drivers/soc/samsung/exynos-chipid.c

diff --git a/drivers/soc/samsung/Kconfig b/drivers/soc/samsung/Kconfig
index 2455339..f9ab858 100644
--- a/drivers/soc/samsung/Kconfig
+++ b/drivers/soc/samsung/Kconfig

@@ -14,4 +14,9 @@ config EXYNOS_PM_DOMAINS
 	bool "Exynos PM domains" if COMPILE_TEST
 	depends on PM_GENERIC_DOMAINS || COMPILE_TEST
 
+config EXYNOS_CHIPID
+	bool "Exynos Chipid controller driver" if COMPILE_TEST
+	depends on (ARM && ARCH_EXYNOS) || ((ARM || ARM64) && COMPILE_TEST)
+	select SOC_BUS
+
 endif

diff --git a/drivers/soc/samsung/Makefile b/drivers/soc/samsung/Makefile
index 3619f2e..2a8a85e 100644
--- a/drivers/soc/samsung/Makefile
+++ b/drivers/soc/samsung/Makefile

@@ -1,3 +1,4 @@
 obj-$(CONFIG_EXYNOS_PMU)	+= exynos-pmu.o exynos3250-pmu.o exynos4-pmu.o \
 					exynos5250-pmu.o exynos5420-pmu.o
 obj-$(CONFIG_EXYNOS_PM_DOMAINS) += pm_domains.o
+obj-$(CONFIG_EXYNOS_CHIPID)	+= exynos-chipid.o

diff --git a/drivers/soc/samsung/exynos-chipid.c b/drivers/soc/samsung/exynos-chipid.c
new file mode 100644
index 0000000..cf0128b
--- /dev/null
+++ b/drivers/soc/samsung/exynos-chipid.c

@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2016 Samsung Electronics Co., Ltd.
+ *	      http://www.samsung.com/
+ *
+ * EXYNOS - CHIP ID support
+ * Author: Pankaj Dubey <pankaj.dubey@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+
+#define EXYNOS_SUBREV_MASK	(0xF << 4)
+#define EXYNOS_MAINREV_MASK	(0xF << 0)
+#define EXYNOS_REV_MASK		(EXYNOS_SUBREV_MASK | EXYNOS_MAINREV_MASK)
+
+static const struct exynos_soc_id {
+	const char *name;
+	unsigned int id;
+	unsigned int mask;
+} soc_ids[] = {
+	{ "EXYNOS3250", 0xE3472000, 0xFFFFF000 },
+	{ "EXYNOS4210", 0x43200000, 0xFFFE0000 },
+	{ "EXYNOS4212", 0x43220000, 0xFFFE0000 },
+	{ "EXYNOS4412", 0xE4412000, 0xFFFE0000 },
+	{ "EXYNOS5250", 0x43520000, 0xFFFFF000 },
+	{ "EXYNOS5260", 0xE5260000, 0xFFFFF000 },
+	{ "EXYNOS5410", 0xE5410000, 0xFFFFF000 },
+	{ "EXYNOS5420", 0xE5420000, 0xFFFFF000 },
+	{ "EXYNOS5440", 0xE5440000, 0xFFFFF000 },
+	{ "EXYNOS5800", 0xE5422000, 0xFFFFF000 },
+	{ "EXYNOS7420", 0xE7420000, 0xFFFFF000 },
+	{ "EXYNOS5433", 0xE5433000, 0xFFFFF000 },
+};
+
+static const char * __init product_id_to_soc_id(unsigned int product_id)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(soc_ids); i++)
+		if ((product_id & soc_ids[i].mask) == soc_ids[i].id)
+			return soc_ids[i].name;
+	return "UNKNOWN";
+}
+
+static const struct of_device_id of_exynos_chipid_ids[] = {
+	{
+		.compatible	= "samsung,exynos4210-chipid",
+	},
+	{},
+};
+
+/**
+ *  exynos_chipid_early_init: Early chipid initialization
+ */
+int __init exynos_chipid_early_init(void)
+{
+	struct soc_device_attribute *soc_dev_attr;
+	struct soc_device *soc_dev;
+	struct device_node *root;
+	struct device_node *np;
+	void __iomem *exynos_chipid_base;
+	const struct of_device_id *match;
+	u32 product_id;
+	u32 revision;
+
+	np = of_find_matching_node_and_match(NULL,
+			of_exynos_chipid_ids, &match);
+	if (!np)
+		return -ENODEV;
+
+	exynos_chipid_base = of_iomap(np, 0);
+
+	if (!exynos_chipid_base)
+		return PTR_ERR(exynos_chipid_base);
+
+	product_id  = readl_relaxed(exynos_chipid_base);
+	revision = product_id & EXYNOS_REV_MASK;
+	iounmap(exynos_chipid_base);
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENODEV;
+
+	soc_dev_attr->family = "Samsung Exynos";
+
+	root = of_find_node_by_path("/");
+	of_property_read_string(root, "model", &soc_dev_attr->machine);
+	of_node_put(root);
+
+	soc_dev_attr->revision = kasprintf(GFP_KERNEL, "%x", revision);
+	soc_dev_attr->soc_id = product_id_to_soc_id(product_id);
+
+
+	pr_info("Exynos: CPU[%s] CPU_REV[0x%x] Detected\n",
+			product_id_to_soc_id(product_id), revision);
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr->revision);
+		kfree_const(soc_dev_attr->soc_id);
+		kfree(soc_dev_attr);
+		return PTR_ERR(soc_dev);
+	}
+
+	return 0;
+}
+early_initcall(exynos_chipid_early_init);