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    Subject[PATCH v12 net-next 1/9] mfd: ocelot: add helper to get regmap from a resource
    Date
    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.

    Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
    ---
    MAINTAINERS | 5 ++++
    include/linux/mfd/ocelot.h | 51 ++++++++++++++++++++++++++++++++++++++
    2 files changed, 56 insertions(+)
    create mode 100644 include/linux/mfd/ocelot.h

    diff --git a/MAINTAINERS b/MAINTAINERS
    index 7c029ab73265..c2f61ed1b730 100644
    --- a/MAINTAINERS
    +++ b/MAINTAINERS
    @@ -14413,6 +14413,11 @@ 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..7e64870b75ca
    --- /dev/null
    +++ b/include/linux/mfd/ocelot.h
    @@ -0,0 +1,51 @@
    +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
    +/* Copyright 2022 Innovative Advantage Inc. */
    +
    +#include <linux/err.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;
    + u32 __iomem *regs;
    +
    + 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) ? map : ERR_PTR(-ENOENT);
    +}
    --
    2.25.1
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