On Tue, Jun 28, 2022 at 01:17:01AM -0700, Colin Foster wrote:

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....