Date:   Thu, 16 May 2019 14:09:38 +0000
From:   Aisheng Dong <aisheng.dong@....com>
To:     Anson Huang <anson.huang@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "agross@...nel.org" <agross@...nel.org>,
        "maxime.ripard@...tlin.com" <maxime.ripard@...tlin.com>,
        "olof@...om.net" <olof@...om.net>,
        "horms+renesas@...ge.net.au" <horms+renesas@...ge.net.au>,
        "jagan@...rulasolutions.com" <jagan@...rulasolutions.com>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        Leonard Crestez <leonard.crestez@....com>,
        "marc.w.gonzalez@...e.fr" <marc.w.gonzalez@...e.fr>,
        "dinguyen@...nel.org" <dinguyen@...nel.org>,
        "enric.balletbo@...labora.com" <enric.balletbo@...labora.com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        Abel Vesa <abel.vesa@....com>,
        "robh@...nel.org" <robh@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V3 1/2] soc: imx: Add SCU SoC info driver support

> From: Anson Huang
> Sent: Thursday, May 16, 2019 8:01 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 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@....com>
> > > ---
> > > 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,
> >
> > This is still follow a generic soc driver design.
> > I wonder if this is still needed after separate scu soc driver from imx8m.
> > If not needed, this driver probably could be simplied a lot.
> 
> Using generic soc driver is just to provide different soc data for different SoCs,
> NOT sure if we can cover all SCU SoCs using same settings. Different SoCs may
> need some different operations or workarounds, like i.MX8QM needs some
> special workaround settings....
> 

Mx8qm seems can fully re-use imx8qxp_soc_revision().
And the workaround in local tree seems not need to be put there.
Then the left one is only soc name?

> >
> > > +};
> > > +
> > > +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);
> >
> > Use of_find_compatible_node instead.
> > Then you remove two unnecessary local variable.
> 
> OK.
> 
> >
> > BTW, probably a better way is to match "fsl,imx-scu"?
> 
> "fsl,imx-scu" already used by scu firmware driver, that will cause confusion I
> think, just using soc's compatible should be easier to understand.
> 

It does not matter because we only use it to check whether we need register
this soc driver. And what I suggest is because this drive actually depends on
"fsl,imx-scu", not soc compatible string.
Another benefit is you do not need another compatible string when you
Add imx8qm support.

> >
> > > +	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;
> >
> > Please double check if we really need a global imx_scu_soc_pdev.
> 
> Global platform_device pointer can be used in other function's message output
> using dev_xxx instead of pr_xxx, and it could be needed later for some other
> functions, if no big concern of keeping one global variable, I prefer to keep it.
> 

I mean If we remove soc_revision() callback, we may not need it.
And imx_scu_soc_match array could also be removed. Then the driver could
Be simplified a lot.

You can check if we can do that.

Regards
Dong Aisheng

> Thanks,
> Anson
> 
> >
> > Regards
> > Dong Aisheng
> >
> > > +
> > > +	return 0;
> > > +
> > > +unreg_platform_driver:
> > > +	platform_driver_unregister(&imx_scu_soc_driver);
> > > +	return ret;
> > > +}
> > > +device_initcall(imx_scu_soc_init);
> > > --
> > > 2.7.4

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