soc: imx: Add SCU SoC info driver support

Add i.MX SCU SoC info driver to support i.MX8QXP SoC, introduce
driver dependency into Kconfig as CONFIG_IMX_SCU must be
selected to support i.MX SCU SoC driver, also need to use
platform driver model to make sure IMX_SCU driver is probed
before i.MX SCU SoC driver.

With this patch, SoC info can be read from sysfs:

i.mx8qxp-mek# cat /sys/devices/soc0/family
Freescale i.MX

i.mx8qxp-mek# cat /sys/devices/soc0/soc_id
0x2

i.mx8qxp-mek# cat /sys/devices/soc0/machine
Freescale i.MX8QXP MEK

i.mx8qxp-mek# cat /sys/devices/soc0/revision
1.1
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/soc/imx/Kconfig

@@ -7,4 +7,13 @@ config IMX_GPCV2_PM_DOMAINS
 	select PM_GENERIC_DOMAINS
 	default y if SOC_IMX7D
 
+config IMX_SCU_SOC
+	bool "i.MX System Controller Unit SoC info support"
+	depends on IMX_SCU
+	select SOC_BUS
+	help
+	  If you say yes here you get support for the NXP i.MX System
+	  Controller Unit SoC info module, it will provide the SoC info
+	  like SoC family, ID and revision etc.
+
 endmenu

drivers/soc/imx/Makefile

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

drivers/soc/imx/soc-imx-scu.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP.
+ */
+
+#include <dt-bindings/firmware/imx/rsrc.h>
+#include <linux/firmware/imx/sci.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+
+#define IMX_SCU_SOC_DRIVER_NAME		"imx-scu-soc"
+
+static struct imx_sc_ipc *soc_ipc_handle;
+
+struct imx_sc_msg_misc_get_soc_id {
+	struct imx_sc_rpc_msg hdr;
+	union {
+		struct {
+			u32 control;
+			u16 resource;
+		} __packed req;
+		struct {
+			u32 id;
+		} resp;
+	} data;
+} __packed;
+
+static int imx_scu_soc_id(void)
+{
+	struct imx_sc_msg_misc_get_soc_id msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	int ret;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = IMX_SC_RPC_SVC_MISC;
+	hdr->func = IMX_SC_MISC_FUNC_GET_CONTROL;
+	hdr->size = 3;
+
+	msg.data.req.control = IMX_SC_C_ID;
+	msg.data.req.resource = IMX_SC_R_SYSTEM;
+
+	ret = imx_scu_call_rpc(soc_ipc_handle, &msg, true);
+	if (ret) {
+		pr_err("%s: get soc info failed, ret %d\n", __func__, ret);
+		return ret;
+	}
+
+	return msg.data.resp.id;
+}
+
+static int imx_scu_soc_probe(struct platform_device *pdev)
+{
+	struct soc_device_attribute *soc_dev_attr;
+	struct soc_device *soc_dev;
+	int id, ret;
+	u32 val;
+
+	ret = imx_scu_get_handle(&soc_ipc_handle);
+	if (ret)
+		return ret;
+
+	soc_dev_attr = devm_kzalloc(&pdev->dev, sizeof(*soc_dev_attr),
+				    GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	soc_dev_attr->family = "Freescale i.MX";
+
+	ret = of_property_read_string(of_root,
+				      "model",
+				      &soc_dev_attr->machine);
+	if (ret)
+		return ret;
+
+	id = imx_scu_soc_id();
+	if (id < 0)
+		return -EINVAL;
+
+	/* format soc_id value passed from SCU firmware */
+	val = id & 0x1f;
+	soc_dev_attr->soc_id = kasprintf(GFP_KERNEL, "0x%x", val);
+	if (!soc_dev_attr->soc_id)
+		return -ENOMEM;
+
+	/* format revision value passed from SCU firmware */
+	val = (id >> 5) & 0xf;
+	val = (((val >> 2) + 1) << 4) | (val & 0x3);
+	soc_dev_attr->revision = kasprintf(GFP_KERNEL,
+					   "%d.%d",
+					   (val >> 4) & 0xf,
+					   val & 0xf);
+	if (!soc_dev_attr->revision) {
+		ret = -ENOMEM;
+		goto free_soc_id;
+	}
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		ret = PTR_ERR(soc_dev);
+		goto free_revision;
+	}
+
+	return 0;
+
+free_revision:
+	kfree(soc_dev_attr->revision);
+free_soc_id:
+	kfree(soc_dev_attr->soc_id);
+	return ret;
+}
+
+static struct platform_driver imx_scu_soc_driver = {
+	.driver = {
+		.name = IMX_SCU_SOC_DRIVER_NAME,
+	},
+	.probe = imx_scu_soc_probe,
+};
+
+static int __init imx_scu_soc_init(void)
+{
+	struct platform_device *pdev;
+	struct device_node *np;
+	int ret;
+
+	np = of_find_compatible_node(NULL, NULL, "fsl,imx-scu");
+	if (!np)
+		return -ENODEV;
+
+	of_node_put(np);
+
+	ret = platform_driver_register(&imx_scu_soc_driver);
+	if (ret)
+		return ret;
+
+	pdev = platform_device_register_simple(IMX_SCU_SOC_DRIVER_NAME,
+					       -1, NULL, 0);
+	if (IS_ERR(pdev))
+		platform_driver_unregister(&imx_scu_soc_driver);
+
+	return PTR_ERR_OR_ZERO(pdev);
+}
+device_initcall(imx_scu_soc_init);