[PATCH V3 1/2] soc: imx: Add SCU SoC info driver support

[Anson Huang]

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
i.MX8QXP

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@xxxxxxx>
---
Changes since V2:
	- using device_initcall instead of module_init;
	- check of_match_node in init function and ONLY register platform driver when matched, this
	  is to avoid unnecessary probe for non SCU based i.MX8 SoCs.
---
 drivers/soc/imx/Kconfig       |   9 +++
 drivers/soc/imx/Makefile      |   1 +
 drivers/soc/imx/soc-imx-scu.c | 173 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 183 insertions(+)
 create mode 100644 drivers/soc/imx/soc-imx-scu.c

diff --git a/drivers/soc/imx/Kconfig b/drivers/soc/imx/Kconfig
index d80f899..cbc1a41 100644
--- a/drivers/soc/imx/Kconfig
+++ b/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
diff --git a/drivers/soc/imx/Makefile b/drivers/soc/imx/Makefile
index d6b529e0..ddf343d 100644
--- a/drivers/soc/imx/Makefile
+++ b/drivers/soc/imx/Makefile
@@ -1,3 +1,4 @@
 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
diff --git a/drivers/soc/imx/soc-imx-scu.c b/drivers/soc/imx/soc-imx-scu.c
new file mode 100644
index 0000000..243c418
--- /dev/null
+++ b/drivers/soc/imx/soc-imx-scu.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP.
+ */
+
+#include <dt-bindings/firmware/imx/rsrc.h>
+#include <linux/firmware/imx/sci.h>
+#include <linux/module.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;
+static struct platform_device *imx_scu_soc_pdev;
+
+struct imx_sc_msg_misc_get_soc_id {
+	struct imx_sc_rpc_msg hdr;
+	union {
+		struct {
+			u32 control;
+			u16 resource;
+		} send;
+		struct {
+			u32 id;
+			u16 reserved;
+		} resp;
+	} data;
+} __packed;
+
+struct imx_scu_soc_data {
+	char *name;
+	u32 (*soc_revision)(void);
+};
+
+static u32 imx8qxp_soc_revision(void)
+{
+	struct imx_sc_msg_misc_get_soc_id msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	u32 rev;
+	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.send.control = IMX_SC_C_ID;
+	msg.data.send.resource = IMX_SC_R_SYSTEM;
+
+	ret = imx_scu_call_rpc(soc_ipc_handle, &msg, true);
+	if (ret) {
+		dev_err(&imx_scu_soc_pdev->dev,
+			"get soc info failed, ret %d\n", ret);
+		/* return 0 means getting revision failed */
+		return 0;
+	}
+
+	/* format revision value passed from SCU firmware */
+	rev = (msg.data.resp.id >> 5) & 0xf;
+	rev = (((rev >> 2) + 1) << 4) | (rev & 0x3);
+
+	return rev;
+}
+
+static const struct imx_scu_soc_data imx8qxp_soc_data = {
+	.name = "i.MX8QXP",
+	.soc_revision = imx8qxp_soc_revision,
+};
+
+static const struct of_device_id imx_scu_soc_match[] = {
+	{ .compatible = "fsl,imx8qxp", .data = &imx8qxp_soc_data, },
+	{ }
+};
+
+#define imx_scu_revision(soc_rev) \
+	soc_rev ? \
+	kasprintf(GFP_KERNEL, "%d.%d", (soc_rev >> 4) & 0xf,  soc_rev & 0xf) : \
+	"unknown"
+
+static int imx_scu_soc_probe(struct platform_device *pdev)
+{
+	struct soc_device_attribute *soc_dev_attr;
+	const struct imx_scu_soc_data *data;
+	const struct of_device_id *id;
+	struct soc_device *soc_dev;
+	u32 soc_rev = 0;
+	int ret;
+
+	/* wait i.MX SCU driver ready */
+	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(pdev->dev.of_node,
+				      "model",
+				      &soc_dev_attr->machine);
+	if (ret)
+		return ret;
+
+	id = of_match_node(imx_scu_soc_match, pdev->dev.of_node);
+	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 = imx_scu_revision(soc_rev);
+	if (!soc_dev_attr->revision)
+		return -ENODEV;
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr->revision);
+		return PTR_ERR(soc_dev);
+	}
+
+	return 0;
+}
+
+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)
+{
+	const struct of_device_id *id;
+	struct device_node *root;
+	int ret;
+
+	root = of_find_node_by_path("/");
+	id = of_match_node(imx_scu_soc_match, root);
+	if (!id) {
+		of_node_put(root);
+		return -ENODEV;
+	}
+
+	ret = platform_driver_register(&imx_scu_soc_driver);
+	if (ret)
+		return ret;
+
+	imx_scu_soc_pdev =
+		platform_device_register_simple(IMX_SCU_SOC_DRIVER_NAME,
+						-1,
+						NULL,
+						0);
+	if (IS_ERR(imx_scu_soc_pdev)) {
+		ret = PTR_ERR(imx_scu_soc_pdev);
+		goto unreg_platform_driver;
+	}
+
+	imx_scu_soc_pdev->dev.of_node = root;
+
+	return 0;
+
+unreg_platform_driver:
+	platform_driver_unregister(&imx_scu_soc_driver);
+	return ret;
+}
+device_initcall(imx_scu_soc_init);
-- 
2.7.4