soc: imx: Add SoC device register for i.MX9

i.MX9 SoCs have SoC ID, SoC revision number and chip unique identifier
which are provided by the corresponding ARM trusted firmware API. This
patch intends to use SMC call to obtain these information and then
register i.MX9 SoC as a device.

Signed-off-by: Alice Guo <alice.guo@nxp.com>
Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/soc/imx/Makefile

@@ -3,4 +3,4 @@ ifeq ($(CONFIG_ARM),y)
 obj-$(CONFIG_ARCH_MXC) += soc-imx.o
 endif
 obj-$(CONFIG_SOC_IMX8M) += soc-imx8m.o
-obj-$(CONFIG_SOC_IMX9) += imx93-src.o
+obj-$(CONFIG_SOC_IMX9) += imx93-src.o soc-imx9.o

drivers/soc/imx/soc-imx9.c

@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2024 NXP
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+
+#define IMX_SIP_GET_SOC_INFO	0xc2000006
+#define SOC_ID(x)		(((x) & 0xFFFF) >> 8)
+#define SOC_REV_MAJOR(x)	((((x) >> 28) & 0xF) - 0x9)
+#define SOC_REV_MINOR(x)	(((x) >> 24) & 0xF)
+
+static int imx9_soc_probe(struct platform_device *pdev)
+{
+	struct soc_device_attribute *attr;
+	struct arm_smccc_res res;
+	struct soc_device *sdev;
+	u32 soc_id, rev_major, rev_minor;
+	u64 uid127_64, uid63_0;
+	int err;
+
+	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
+	if (!attr)
+		return -ENOMEM;
+
+	err = of_property_read_string(of_root, "model", &attr->machine);
+	if (err) {
+		pr_err("%s: missing model property: %d\n", __func__, err);
+		goto attr;
+	}
+
+	attr->family = kasprintf(GFP_KERNEL, "Freescale i.MX");
+
+	/*
+	 * Retrieve the soc id, rev & uid info:
+	 * res.a1[31:16]: soc revision;
+	 * res.a1[15:0]: soc id;
+	 * res.a2: uid[127:64];
+	 * res.a3: uid[63:0];
+	 */
+	arm_smccc_smc(IMX_SIP_GET_SOC_INFO, 0, 0, 0, 0, 0, 0, 0, &res);
+	if (res.a0 != SMCCC_RET_SUCCESS) {
+		pr_err("%s: SMC failed: 0x%lx\n", __func__, res.a0);
+		err = -EINVAL;
+		goto family;
+	}
+
+	soc_id = SOC_ID(res.a1);
+	rev_major = SOC_REV_MAJOR(res.a1);
+	rev_minor = SOC_REV_MINOR(res.a1);
+
+	attr->soc_id = kasprintf(GFP_KERNEL, "i.MX%2x", soc_id);
+	attr->revision = kasprintf(GFP_KERNEL, "%d.%d", rev_major, rev_minor);
+
+	uid127_64 = res.a2;
+	uid63_0 = res.a3;
+	attr->serial_number = kasprintf(GFP_KERNEL, "%016llx%016llx", uid127_64, uid63_0);
+
+	sdev = soc_device_register(attr);
+	if (IS_ERR(sdev)) {
+		err = PTR_ERR(sdev);
+		pr_err("%s failed to register SoC as a device: %d\n", __func__, err);
+		goto serial_number;
+	}
+
+	return 0;
+
+serial_number:
+	kfree(attr->serial_number);
+	kfree(attr->revision);
+	kfree(attr->soc_id);
+family:
+	kfree(attr->family);
+attr:
+	kfree(attr);
+	return err;
+}
+
+static __maybe_unused const struct of_device_id imx9_soc_match[] = {
+	{ .compatible = "fsl,imx93", },
+	{ .compatible = "fsl,imx95", },
+	{ }
+};
+
+#define IMX_SOC_DRIVER	"imx9-soc"
+
+static struct platform_driver imx9_soc_driver = {
+	.probe = imx9_soc_probe,
+	.driver = {
+		.name = IMX_SOC_DRIVER,
+	},
+};
+
+static int __init imx9_soc_init(void)
+{
+	int ret;
+	struct platform_device *pdev;
+
+	/* No match means it is not an i.MX 9 series SoC, do nothing. */
+	if (!of_match_node(imx9_soc_match, of_root))
+		return 0;
+
+	ret = platform_driver_register(&imx9_soc_driver);
+	if (ret) {
+		pr_err("failed to register imx9_soc platform driver: %d\n", ret);
+		return ret;
+	}
+
+	pdev = platform_device_register_simple(IMX_SOC_DRIVER, -1, NULL, 0);
+	if (IS_ERR(pdev)) {
+		pr_err("failed to register imx9_soc platform device: %ld\n", PTR_ERR(pdev));
+		platform_driver_unregister(&imx9_soc_driver);
+		return PTR_ERR(pdev);
+	}
+
+	return 0;
+}
+device_initcall(imx9_soc_init);
+
+MODULE_AUTHOR("NXP");
+MODULE_DESCRIPTION("NXP i.MX9 SoC");
+MODULE_LICENSE("GPL");