1 files changed, 62 insertions, 0 deletions
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