RE: [PATCH V5 1/2] soc: imx: Add SCU SoC info driver support

[Aisheng Dong <aisheng.dong@nxp.com>]

> From: Anson Huang
> Sent: Wednesday, May 22, 2019 2:24 PM
> 
> 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>

A few minor comments below,
Otherwise:
Dong Aisheng <aisheng.dong@nxp.com>

> ---
> Changes since V4:
> 	- using extern struct of_root instead of searching it again from DT;
> 	- add of_node_put() after "fsl,imx-scu" is found.
> ---
>  drivers/soc/imx/Kconfig       |   9 +++
>  drivers/soc/imx/Makefile      |   1 +
>  drivers/soc/imx/soc-imx-scu.c | 155
> ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 165 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..17deb4e
> --- /dev/null
> +++ b/drivers/soc/imx/soc-imx-scu.c
> @@ -0,0 +1,155 @@
> +// 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;
> +		} send;

Please follow the exist naming conversion to avoid a diverge if no specific reasons.
s/send/req

BTW, sub structures also needs packed and better add an explicit __packed
As I'm not sure whether GCC will always generate no padding for ARM64 platforms
For above structures.

> +		struct {
> +			u32 id;
> +			u16 reserved;

What's reserved member for?

> +		} resp;
> +	} data;
> +} __packed;
> +
> +static u32 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.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) {
> +		pr_err("%s: get soc info failed, ret %d\n", __func__, ret);
> +		/* return 0 means getting revision failed */
> +		return 0;
> +	}
> +
> +	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;
> +	u32 id, val;
> +	int ret;
> +
> +	/* wait i.MX SCU driver ready */

Nitpick: remove this unnecessary line

> +	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();
> +
> +	/* format soc_id value passed from SCU firmware */
> +	val = id & 0x1f;
> +	soc_dev_attr->soc_id = val ? kasprintf(GFP_KERNEL, "0x%x", val)
> +			       : "unknown";
> +	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 = val ? kasprintf(GFP_KERNEL,
> +						 "%d.%d",
> +						 (val >> 4) & 0xf,
> +						 val & 0xf) : "unknown";
> +	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 *imx_scu_soc_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;
> +
> +	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;
> +	}
> +
> +	return 0;
> +
> +unreg_platform_driver:
> +	platform_driver_unregister(&imx_scu_soc_driver);
> +	return ret;
> +}

This could be simplied with 3 lines:
If (IS_ERR(pdev))
	Platform_driver_unregsiter(xxx)

Return PTR_ERR_OR_ZERO(pdev)

Regards
Dong Aisheng

> +device_initcall(imx_scu_soc_init);
> --
> 2.7.4

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