[v14,mfd,1/9] mfd: ocelot: add helper to get regmap from a resource

Commit Message

Colin Foster July 22, 2022, 4:06 a.m. UTC

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 <[e-mail]>
Reviewed-by: Vladimir Oltean <[e-mail]>
---

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

---
 MAINTAINERS                |  5 ++++
 include/linux/mfd/ocelot.h | 60 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 include/linux/mfd/ocelot.h

Comments

Andy Shevchenko July 25, 2022, 9:39 a.m. UTC | #1

On Fri, Jul 22, 2022 at 6:06 AM Colin Foster
<[e-mail]> wrote:
>
> 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.

When we refer to functions we put it like func().

> 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.

...

> +#include <linux/err.h>

You also missed errno.h

> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>

...

> +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

_get_and_ioremap_resource()

> +        * prints of "invalid resource" which simply add confusion
> +        */

will simply add

Missed period.

> +       res = platform_get_resource(pdev, IORESOURCE_MEM, index);

Where are the IORESOURCE_*  defined? Haven't you missed a header?

> +       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;
> +}

Colin Foster July 25, 2022, 3:46 p.m. UTC | #2

Hi Andy,

Great catches as always. Thank you.

I'll wait for Lee to take a look before blasting out another version.
I'm still holding out hope for this upcoming merge window!

Lee Jones Aug. 1, 2022, 2:45 p.m. UTC | #3

On Mon, 25 Jul 2022, Colin Foster wrote:

> Hi Andy,
> 
> Great catches as always. Thank you.
> 
> I'll wait for Lee to take a look before blasting out another version.
> I'm still holding out hope for this upcoming merge window!

No chance. :)

Please submit the latest version.

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 28108e4fdb8f..f781caceeb38 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14467,6 +14467,11 @@  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 <[e-mail]>
+S:	Supported
+F:	include/linux/mfd/ocelot.h
+
 OCXL (Open Coherent Accelerator Processor Interface OpenCAPI) DRIVER
 M:	Frederic Barrat <[e-mail]>
 M:	Andrew Donnellan <[e-mail]>
diff --git a/include/linux/mfd/ocelot.h b/include/linux/mfd/ocelot.h
new file mode 100644
index 000000000000..7abca80ba7dc
--- /dev/null
+++ b/include/linux/mfd/ocelot.h
@@ -0,0 +1,60 @@ 
+/* 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/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 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