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Message-ID: <20220726075100epcms1p105e6df50e1efb6fc43786699d223c051@epcms1p1>
Date:   Tue, 26 Jul 2022 16:51:00 +0900
From:   Dongjin Yang <dj76.yang@...sung.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "jesper.nilsson@...s.com" <jesper.nilsson@...s.com>,
        "lars.persson@...s.com" <lars.persson@...s.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>
CC:     "javierm@...hat.com" <javierm@...hat.com>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "linux-arm-kernel@...s.com" <linux-arm-kernel@...s.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Moon-Ki Jun <moonki.jun@...sung.com>,
        Sang Min Kim <hypmean.kim@...sung.com>,
        Wangseok Lee <wangseok.lee@...sung.com>
Subject: Re: [PATCH 4/4] mfd: Samsung: Add Samsung sysmgr driver

On 14/07/2022 04:28, Krzysztof Kozlowski wrote:
> On 13/07/2022 06:57, Dongjin Yang wrote:
> > This driver is used for SoCs produced by Samsung Foundry to provide
> > Samsung sysmgr API. The read/write request of sysmgr is delivered to
> > Samsung secure monitor call.
> > 
> > Signed-off-by: Dongjin Yang <dj76.yang@...sung.com>
> > ---
> >  MAINTAINERS                        |   2 +
> >  drivers/mfd/Kconfig                |  11 +++
> >  drivers/mfd/Makefile               |   1 +
> >  drivers/mfd/samsung-sysmgr.c       | 167 +++++++++++++++++++++++++++++++++++++
> >  include/linux/mfd/samsung-sysmgr.h |  30 +++++++
> >  5 files changed, 211 insertions(+)
> >  create mode 100644 drivers/mfd/samsung-sysmgr.c
> >  create mode 100644 include/linux/mfd/samsung-sysmgr.h
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 55cb8901ccdc..44ad4bd406a9 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -1870,9 +1870,11 @@ F:        arch/arm/mach-artpec
> >  F:        drivers/clk/axis
> >  F:        drivers/crypto/axis
> >  F:        drivers/firmware/samsung-smc-svc.c
> > +F:        drivers/mfd/samsung-sysmgr.c
> >  F:        drivers/mmc/host/usdhi6rol0.c
> >  F:        drivers/pinctrl/pinctrl-artpec*
> >  F:        include/linux/firmware/samsung-smc-svc.h
> > +F:        include/linux/mfd/samsung-sysmgr.h
> 
> Not related to Axis/Artpec SoC.
> 

It is Artpec8 SoC.

> >  
> >  ARM/ASPEED I2C DRIVER
> >  M:        Brendan Higgins <brendanhiggins@...gle.com>
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index 3b59456f5545..ce6ab5842bf0 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -51,6 +51,17 @@ config MFD_ACT8945A
> >            linear regulators, along with a complete ActivePath battery
> >            charger.
> >  
> > +config MFD_SAMSUNG_SYSMGR
> > +        bool "System Manager for Samsung Foundry platforms"
> > +        depends on ARCH_ARTPEC && OF
> 
> Samsung Foundry does not match ARTPEC... Artpec 6 is not Samsung Foundry
> SoC, is it?
> 

This is for Artpec8. 

> Missing compile test.
> 

Sorry, I will run it.

> > +        select MFD_SYSCON
> > +        select SAMSUNG_SECURE_SERVICE
> > +        help
> > +          Select this to get System Manager support for SoCs which use
> > +          Samsung Foundry platforms.
> > +          This System Manager has depedency on Samsung Secure Service
> > +          for providing secure service call.
> 
> Looking at the driver, it does literally nothing. Looks like workaround
> for incomplete bindings and DTS. It's a no-go.
> 

This driver is for providing secure smc read/write to other IP driver in Artpec8 SoC.


> > +
> >  config MFD_SUN4I_GPADC
> >          tristate "Allwinner sunxi platforms' GPADC MFD driver"
> >          select MFD_CORE
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index 858cacf659d6..490f041d1262 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -248,6 +248,7 @@ obj-$(CONFIG_INTEL_SOC_PMIC_MRFLD)        += intel_soc_pmic_mrfld.o
> >  
> >  obj-$(CONFIG_MFD_ALTERA_A10SR)        += altera-a10sr.o
> >  obj-$(CONFIG_MFD_ALTERA_SYSMGR) += altera-sysmgr.o
> > +obj-$(CONFIG_MFD_SAMSUNG_SYSMGR) += samsung-sysmgr.o
> >  obj-$(CONFIG_MFD_STPMIC1)        += stpmic1.o
> >  obj-$(CONFIG_MFD_SUN4I_GPADC)        += sun4i-gpadc.o
> >  
> > diff --git a/drivers/mfd/samsung-sysmgr.c b/drivers/mfd/samsung-sysmgr.c
> > new file mode 100644
> > index 000000000000..a202e8c4c4f2
> > --- /dev/null
> > +++ b/drivers/mfd/samsung-sysmgr.c
> > @@ -0,0 +1,167 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Samsung Electronics, Co. Ltd.
> > + * Copyright (C) 2018-2019, Intel Corporation.
> > + * Copyright (C) 2012 Freescale Semiconductor, Inc.
> > + * Copyright (C) 2012 Linaro Ltd.
> > + *
> > + * Inspired by drivers/mfd/altera-sysmgr.c
> > + */
> > +
> > +#include <linux/arm-smccc.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/mfd/samsung-sysmgr.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/regmap.h>
> > +#include <linux/slab.h>
> > +
> > +/**
> > + * struct samsung_sysmgr - Samsung System Manager
> > + * @regmap: the regmap used for System Manager accesses.
> > + * @base  : the base address for the System Manager
> > + */
> > +struct samsung_sysmgr {
> > +        struct regmap   *regmap;
> > +        resource_size_t *base;
> > +};
> > +
> > +static struct platform_driver samsung_sysmgr_driver;
> 
> No, no static variables.
> 

Ok, I will change this.

> > +
> > +static struct regmap_config mmio_regmap_cfg = {
> > +        .name = "sysmgr_mmio",
> > +        .reg_bits = 32,
> > +        .reg_stride = 4,
> > +        .val_bits = 32,
> > +        .fast_io = true,
> > +        .use_single_read = true,
> > +        .use_single_write = true,
> > +};
> > +
> > +static struct regmap_config samsung_smccc_regmap_cfg = {
> > +        .name = "samsung_sysmgr_smccc",
> > +        .reg_bits = 32,
> > +        .reg_stride = 4,
> > +        .val_bits = 32,
> > +        .fast_io = true,
> > +        .use_single_read = true,
> > +        .use_single_write = true,
> > +        .reg_read = samsung_smc_reg_read,
> > +        .reg_write = samsung_smc_reg_write,
> > +};
> > +
> > +/**
> > + * samsung_sysmgr_regmap_lookup_by_phandle
> > + * Find the sysmgr previous configured in probe() and return regmap property.
> > + * Return: regmap if found or error if not found.
> > + */
> > +struct regmap *samsung_sysmgr_regmap_lookup_by_phandle(struct device_node *np,
> > +                                                       const char *property)
> > +{
> > +        struct device *dev;
> > +        struct samsung_sysmgr *sysmgr;
> > +        struct device_node *sysmgr_np;
> > +
> > +        if (property)
> > +                sysmgr_np = of_parse_phandle(np, property, 0);
> > +        else
> > +                sysmgr_np = np;
> > +
> > +        if (!sysmgr_np)
> > +                return ERR_PTR(-ENODEV);
> > +
> > +        dev = driver_find_device_by_of_node(&samsung_sysmgr_driver.driver,
> > +                                            (void *)sysmgr_np);
> > +        of_node_put(sysmgr_np);
> > +        if (!dev)
> > +                return ERR_PTR(-EPROBE_DEFER);
> > +
> > +        sysmgr = dev_get_drvdata(dev);
> > +
> > +        return sysmgr->regmap;
> > +}
> > +EXPORT_SYMBOL_GPL(samsung_sysmgr_regmap_lookup_by_phandle);
> 
> This breaks layers/encapsulation and looks like a hack for incomplete
> bindings/DTS. No, no exporting regmaps.
> 

Similar with syscon (syscon_regmap_lookup_by_phandle), but needed additional secure smc call.

> > +
> > +static int sysmgr_probe(struct platform_device *pdev)
> > +{
> > +        struct samsung_sysmgr *sysmgr;
> > +        struct regmap *regmap;
> > +        struct resource *res;
> > +        struct device *dev = &pdev->dev;
> > +        struct regmap_config sysmgr_config =
> > +                *((struct regmap_config *)of_device_get_match_data(dev));
> > +
> > +        sysmgr = devm_kzalloc(dev, sizeof(*sysmgr), GFP_KERNEL);
> > +        if (!sysmgr)
> > +                return -ENOMEM;
> > +
> > +        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +        if (!res)
> > +                return -ENOENT;
> > +
> > +        sysmgr_config.max_register = resource_size(res) -
> > +                                     sysmgr_config.reg_stride;
> > +        if (sysmgr_config.reg_read) {
> > +                /* Need physical address for SMCC call */
> > +                sysmgr->base = (resource_size_t *)res->start;
> > +                regmap = devm_regmap_init(dev, NULL, sysmgr->base,
> > +                                          &sysmgr_config);
> > +        } else {
> > +                sysmgr->base = devm_ioremap(dev, res->start,
> > +                                            resource_size(res));
> > +                if (!sysmgr->base)
> > +                        return -ENOMEM;
> > +
> > +                regmap = devm_regmap_init_mmio(dev, sysmgr->base,
> > +                                               &sysmgr_config);
> > +        }
> > +
> > +        if (IS_ERR(regmap)) {
> > +                pr_err("regmap init failed\n");
> 
> dev_err

Will change it.

> 
> > +                return PTR_ERR(regmap);
> > +        }
> > +
> > +        sysmgr->regmap = regmap;
> > +
> > +        platform_set_drvdata(pdev, sysmgr);
> > +
> > +        return 0;
> > +}
> > +
> > +static const struct of_device_id samsung_sysmgr_of_match[] = {
> > +        { .compatible = "samsung,sys-mgr", .data = &mmio_regmap_cfg },
> > +        {
> > +          .compatible = "samsung,sys-mgr-smccc",
> > +          .data = &samsung_smccc_regmap_cfg
> > +        },
> > +        {},
> > +};
> > +MODULE_DEVICE_TABLE(of, samsung_sysmgr_of_match);
> > +
> > +static struct platform_driver samsung_sysmgr_driver = {
> > +        .probe =  sysmgr_probe,
> > +        .driver = {
> > +                .name = "samsung,system_manager",
> > +                .of_match_table = samsung_sysmgr_of_match,
> > +        },
> > +};
> > +
> > +static int __init samsung_sysmgr_init(void)
> > +{
> > +        return platform_driver_register(&samsung_sysmgr_driver);
> > +}
> > +core_initcall(samsung_sysmgr_init);
> 
> module_platform_driver() instead.

ok, I will change it.

> 
> > +
> > +static void __exit samsung_sysmgr_exit(void)
> > +{
> > +        platform_driver_unregister(&samsung_sysmgr_driver);
> > +}
> > +module_exit(samsung_sysmgr_exit);
> > +
> > +MODULE_AUTHOR("Dongjin Yang <dj76.yang@...sung.com>");
> > +MODULE_DESCRIPTION("Samsung System Manager driver");
> > +MODULE_LICENSE("GPL");
> > diff --git a/include/linux/mfd/samsung-sysmgr.h b/include/linux/mfd/samsung-sysmgr.h
> > new file mode 100644
> > index 000000000000..d6887cb86ea8
> > --- /dev/null
> > +++ b/include/linux/mfd/samsung-sysmgr.h
> > @@ -0,0 +1,30 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Copyright (C) 2019 Samsung Electronics, Co. Ltd.
> > + * Copyright (C) 2018-2019 Intel Corporation
> > + * Copyright (C) 2012 Freescale Semiconductor, Inc.
> > + * Copyright (C) 2012 Linaro Ltd.
> > + */
> > +
> > +#ifndef __LINUX_MFD_SAMSUNG_SYSMGR_H__
> > +#define __LINUX_MFD_SAMSUNG_SYSMGR_H__
> > +
> > +#include <linux/err.h>
> > +#include <linux/errno.h>
> > +#include <linux/firmware/samsung-smc-svc.h>
> > +
> > +struct device_node;
> > +
> > +#if defined(CONFIG_MFD_SAMSUNG_SYSMGR)
> 
> No ifdefs, no stubs.
> 

is it ok to move stub code into samsung-smc-svc.c

> 
> 
> Best regards,
> Krzysztof

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