Re: [PATCH v13 net-next 1/9] mfd: ocelot: add helper to get regmap from a resource

Vladimir Oltean
2022-07-09T18:56:25Z

On Tue, Jul 05, 2022 at 01:47:35PM -0700, Colin Foster 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.
>
> Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
> ---

To me this looks good, I'll just add a few minor comments which I think
you don't necessarily need to address by resending, they're just things
I noticed.

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>

> MAINTAINERS | 5 ++++
> include/linux/mfd/ocelot.h | 55 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 60 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..353b7c2ee445
> --- /dev/null
> +++ b/include/linux/mfd/ocelot.h
> @@ -0,0 +1,55 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +/* Copyright 2022 Innovative Advantage Inc. */

A header file should have ifdefs which should prevent double inclusion,
like

#ifndef _MFD_OCELOT_H
#define _MFD_OCELOT_H

...

#endif

> +
> +#include <linux/err.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>
> +
> +struct resource;

IMO if include/linux/platform_device.h doesn't provide "struct resource"
that's a problem for that header to solve, not for its users.

> +
> +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;

"regs" could be void *.

> +
> + /*
> + * Don't use get_and_ioremap_resource here, since that will invoke
> + * prints of "invalid resource" which 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);
> +}
> --
> 2.25.1
>