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References: <20220803054728.1541104-1-colin.foster@in-advantage.com> <20220803054728.1541104-2-colin.foster@in-advantage.com>
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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Wed, 3 Aug 2022 13:31:16 +0200
Message-ID: <CAHp75VcoY+Gr-T9DEvQooPmnwDjPdeZudRwq7L0Bo8vOGdbzOQ@mail.gmail.com>
Subject: Re: [PATCH v15 mfd 1/9] mfd: ocelot: add helper to get regmap from a resource
To:     Colin Foster <colin.foster@in-advantage.com>
Cc:     linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
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On Wed, Aug 3, 2022 at 7:47 AM Colin Foster
<colin.foster@in-advantage.com> wrote:
>
> Several ocelot-related modules are designed for MMIO / regmaps. As such,
> they often use a combination of devm_platform_get_and_ioremap_resource()
> and devm_regmap_init_mmio().
>
> Operating in an MFD might be different, in that it could be memory mapped,
> or it could be SPI, I2C... In these cases a fallback to use IORESOURCE_REG
> instead of IORESOURCE_MEM becomes necessary.
>
> When this happens, there's redundant logic that needs to be implemented in
> every driver. In order to avoid this redundancy, utilize a single function
> that, if the MFD scenario is enabled, will perform this fallback logic.

FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
> Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
>
> v15
>     * Add missed errno.h and ioport.h includes
>     * Add () to function references in both the commit log and comments
>
> v14
>     * Add header guard
>     * Change regs type from u32* to void*
>     * Add Reviewed-by tag
>
> ---
>  MAINTAINERS                |  5 +++
>  include/linux/mfd/ocelot.h | 62 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 67 insertions(+)
>  create mode 100644 include/linux/mfd/ocelot.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 28108e4fdb8f..f781caceeb38 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -14467,6 +14467,11 @@ F:     net/dsa/tag_ocelot.c
>  F:     net/dsa/tag_ocelot_8021q.c
>  F:     tools/testing/selftests/drivers/net/ocelot/*
>
> +OCELOT EXTERNAL SWITCH CONTROL
> +M:     Colin Foster <colin.foster@in-advantage.com>
> +S:     Supported
> +F:     include/linux/mfd/ocelot.h
> +
>  OCXL (Open Coherent Accelerator Processor Interface OpenCAPI) DRIVER
>  M:     Frederic Barrat <fbarrat@linux.ibm.com>
>  M:     Andrew Donnellan <ajd@linux.ibm.com>
> diff --git a/include/linux/mfd/ocelot.h b/include/linux/mfd/ocelot.h
> new file mode 100644
> index 000000000000..dd72073d2d4f
> --- /dev/null
> +++ b/include/linux/mfd/ocelot.h
> @@ -0,0 +1,62 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +/* Copyright 2022 Innovative Advantage Inc. */
> +
> +#ifndef _LINUX_MFD_OCELOT_H
> +#define _LINUX_MFD_OCELOT_H
> +
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/ioport.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>
> +
> +struct resource;
> +
> +static inline struct regmap *
> +ocelot_regmap_from_resource_optional(struct platform_device *pdev,
> +                                    unsigned int index,
> +                                    const struct regmap_config *config)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct resource *res;
> +       void __iomem *regs;
> +
> +       /*
> +        * Don't use _get_and_ioremap_resource() here, since that will invoke
> +        * prints of "invalid resource" which will simply add confusion.
> +        */
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> +       if (res) {
> +               regs = devm_ioremap_resource(dev, res);
> +               if (IS_ERR(regs))
> +                       return ERR_CAST(regs);
> +               return devm_regmap_init_mmio(dev, regs, config);
> +       }
> +
> +       /*
> +        * Fall back to using REG and getting the resource from the parent
> +        * device, which is possible in an MFD configuration
> +        */
> +       if (dev->parent) {
> +               res = platform_get_resource(pdev, IORESOURCE_REG, index);
> +               if (!res)
> +                       return NULL;
> +
> +               return dev_get_regmap(dev->parent, res->name);
> +       }
> +
> +       return NULL;
> +}
> +
> +static inline struct regmap *
> +ocelot_regmap_from_resource(struct platform_device *pdev, unsigned int index,
> +                           const struct regmap_config *config)
> +{
> +       struct regmap *map;
> +
> +       map = ocelot_regmap_from_resource_optional(pdev, index, config);
> +       return map ?: ERR_PTR(-ENOENT);
> +}
> +
> +#endif
> --
> 2.25.1
>


-- 
With Best Regards,
Andy Shevchenko