[RESEND PATCH v16 mfd 1/8] mfd: ocelot: add helper to get regmap from a resource

Colin Foster
2022-09-05T16:22:03Z

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>
---
v16
* Add Andy Reviewed-by tag

v15
* Add missed errno.h and ioport.h includes
* Add () to function references in both the commit log and comments

v14
* Add header guard
* Change regs type from u32* to void*
* Add Reviewed-by tag

---
MAINTAINERS | 5 +++
include/linux/mfd/ocelot.h | 62 ++++++++++++++++++++++++++++++++++++++
2 files changed, 67 insertions(+)
create mode 100644 include/linux/mfd/ocelot.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 8a5012ba6ff9..e0732e9f9090 100644
--- 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
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
--
2.25.1