soc: imx: Add generic i.MX8 SoC driver

Add generic i.MX8 SoC driver along with the i.MX8MQ SoC specific code.
For now, only i.MX8MQ revision B1 is supported. For any other, i.MX8MQ
revision it will print 'unknown'.
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/soc/imx/Makefile

 obj-$(CONFIG_HAVE_IMX_GPC) += gpc.o
 obj-$(CONFIG_IMX_GPCV2_PM_DOMAINS) += gpcv2.o
+obj-$(CONFIG_ARCH_MXC) += soc-imx8.o

drivers/soc/imx/soc-imx8.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP.
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+
+#define REV_B1				0x21
+
+#define IMX8MQ_SW_INFO_B1		0x40
+#define IMX8MQ_SW_MAGIC_B1		0xff0055aa
+
+struct imx8_soc_data {
+	char *name;
+	u32 (*soc_revision)(void);
+};
+
+static u32 __init imx8mq_soc_revision(void)
+{
+	struct device_node *np;
+	void __iomem *ocotp_base;
+	u32 magic;
+	u32 rev = 0;
+
+	np = of_find_compatible_node(NULL, NULL, "fsl,imx8mq-ocotp");
+	if (!np)
+		goto out;
+
+	ocotp_base = of_iomap(np, 0);
+	WARN_ON(!ocotp_base);
+
+	magic = readl_relaxed(ocotp_base + IMX8MQ_SW_INFO_B1);
+	if (magic == IMX8MQ_SW_MAGIC_B1)
+		rev = REV_B1;
+
+	iounmap(ocotp_base);
+
+out:
+	of_node_put(np);
+	return rev;
+}
+
+static const struct imx8_soc_data imx8mq_soc_data = {
+	.name = "i.MX8MQ",
+	.soc_revision = imx8mq_soc_revision,
+};
+
+static const struct of_device_id imx8_soc_match[] = {
+	{ .compatible = "fsl,imx8mq", .data = &imx8mq_soc_data, },
+	{ }
+};
+
+#define imx8_revision(soc_rev) \
+	soc_rev ? \
+	kasprintf(GFP_KERNEL, "%d.%d", (soc_rev >> 4) & 0xf,  soc_rev & 0xf) : \
+	"unknown"
+
+static int __init imx8_soc_init(void)
+{
+	struct soc_device_attribute *soc_dev_attr;
+	struct soc_device *soc_dev;
+	struct device_node *root;
+	const struct of_device_id *id;
+	u32 soc_rev = 0;
+	const struct imx8_soc_data *data;
+	int ret;
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENODEV;
+
+	soc_dev_attr->family = "Freescale i.MX";
+
+	root = of_find_node_by_path("/");
+	ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
+	if (ret)
+		goto free_soc;
+
+	id = of_match_node(imx8_soc_match, root);
+	if (!id)
+		goto free_soc;
+
+	of_node_put(root);
+
+	data = id->data;
+	if (data) {
+		soc_dev_attr->soc_id = data->name;
+		if (data->soc_revision)
+			soc_rev = data->soc_revision();
+	}
+
+	soc_dev_attr->revision = imx8_revision(soc_rev);
+	if (!soc_dev_attr->revision)
+		goto free_soc;
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev))
+		goto free_rev;
+
+	return 0;
+
+free_rev:
+	kfree(soc_dev_attr->revision);
+free_soc:
+	kfree(soc_dev_attr);
+	of_node_put(root);
+	return -ENODEV;
+}
+device_initcall(imx8_soc_init);