mfd: ocelot: Add helper to get regmap from a resource

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>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220905162132.2943088-2-colin.foster@in-advantage.com

diff --git a/MAINTAINERS b/MAINTAINERS
index 8a5012b..e0732e9 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14741,6 +14741,11 @@ 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 (file)
index 0000000..dd72073
--- /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