Re: [PATCH v11 net-next 1/9] mfd: ocelot: add helper to get regmap from a resource

Vladimir Oltean
2022-06-28T16:09:43Z

On Tue, Jun 28, 2022 at 01:17:01AM -0700, Colin Foster wrote:
> diff --git a/include/linux/mfd/ocelot.h b/include/linux/mfd/ocelot.h
> new file mode 100644
> index 000000000000..5c95e4ee38a6
> --- /dev/null
> +++ b/include/linux/mfd/ocelot.h
> @@ -0,0 +1,27 @@
> +/* 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_platform_init_regmap_from_resource(struct platform_device *pdev,
> + unsigned int index,
> + const struct regmap_config *config)

I think this function name is too long (especially if you're going to
also introduce ocelot_platform_init_regmap_from_resource_optional),
and I have the impression that the "platform_init_" part of the name
doesn't bring too much value. How about ocelot_regmap_from_resource()?

> +{
> + struct resource *res;
> + u32 __iomem *regs;
> +
> + regs = devm_platform_get_and_ioremap_resource(pdev, index, &res);
> +
> + if (!res)
> + return ERR_PTR(-ENOENT);
> + else if (IS_ERR(regs))
> + return ERR_CAST(regs);
> + else
> + return devm_regmap_init_mmio(&pdev->dev, regs, config);
> +}
> --
> 2.25.1
>

To illustrate what I'm trying to say, these would be the shim
definitions:

static inline struct regmap *
ocelot_regmap_from_resource(struct platform_device *pdev,
unsigned int index,
const struct regmap_config *config)
{
struct resource *res;
void __iomem *regs;

regs = devm_platform_get_and_ioremap_resource(pdev, index, &res);
if (IS_ERR(regs))
return regs;

return devm_regmap_init_mmio(&pdev->dev, regs, config);
}

static inline struct regmap *
ocelot_regmap_from_resource_optional(struct platform_device *pdev,
unsigned int index,
const struct regmap_config *config)
{
struct resource *res;
void __iomem *regs;

res = platform_get_resource(pdev, IORESOURCE_MEM, index);
if (!res)
return NULL;

regs = devm_ioremap_resource(&pdev->dev, r);
if (IS_ERR(regs))
return regs;

return devm_regmap_init_mmio(&pdev->dev, regs, config);
}

and these would be the full versions:

static struct regmap *
ocelot_regmap_from_mem_resource(struct device *dev, struct resource *res,
const struct regmap_config *config)
{
void __iomem *regs;

regs = devm_ioremap_resource(dev, r);
if (IS_ERR(regs))
return regs;

return devm_regmap_init_mmio(dev, regs, config);
}

static struct regmap *
ocelot_regmap_from_reg_resource(struct device *dev, struct resource *res,
const struct regmap_config *config)
{
/* Open question: how to differentiate SPI from I2C resources? */
return ocelot_spi_init_regmap(dev->parent, dev, res);
}

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;

res = platform_get_resource(pdev, IORESOURCE_MEM, index);
if (res)
return ocelot_regmap_from_mem_resource(dev, res, config);

/*
* Fall back to using IORESOURCE_REG, which is possible in an
* MFD configuration
*/
res = platform_get_resource(pdev, IORESOURCE_REG, index);
if (res)
return ocelot_regmap_from_reg_resource(dev, res, config);

return NULL;
}

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);
}

I hope I didn't get something wrong, this is all code written within the
email client, so it is obviously not compiled/tested....