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 <[email protected]>
---
MAINTAINERS | 5 ++++
include/linux/mfd/ocelot.h | 51 ++++++++++++++++++++++++++++++++++++++
2 files changed, 56 insertions(+)
create mode 100644 include/linux/mfd/ocelot.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 7c029ab73265..c2f61ed1b730 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14413,6 +14413,11 @@ 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 <[email protected]>
+S: Supported
+F: include/linux/mfd/ocelot.h
+
OCXL (Open Coherent Accelerator Processor Interface OpenCAPI) DRIVER
M: Frederic Barrat <[email protected]>
M: Andrew Donnellan <[email protected]>
diff --git a/include/linux/mfd/ocelot.h b/include/linux/mfd/ocelot.h
new file mode 100644
index 000000000000..7e64870b75ca
--- /dev/null
+++ b/include/linux/mfd/ocelot.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/* Copyright 2022 Innovative Advantage Inc. */
+
+#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;
+ u32 __iomem *regs;
+
+ 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) ? map : ERR_PTR(-ENOENT);
+}
--
2.25.1
On Fri, Jul 1, 2022 at 9:26 PM Colin Foster
<[email protected]> 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.
>
> 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.
...
> + res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> + if (res) {
> + regs = devm_ioremap_resource(dev, res);
> + if (IS_ERR(regs))
> + return ERR_CAST(regs);
Why can't it be devm_platform_get_and_ioremap_resource() here?
regs = devm_platform_get_and_ioremap_resource();
if (res) {
if (IS_ERR(regs))
return ERR_CAST();
return ...
}
> + return devm_regmap_init_mmio(dev, regs, config);
> + }
...
> + return (map) ? map : ERR_PTR(-ENOENT);
Too many parentheses.
Also you may use short form of ternary operator:
return map ?: ERR_PTR(-ENOENT);
--
With Best Regards,
Andy Shevchenko
On Fri, Jul 01, 2022 at 10:23:36PM +0200, Andy Shevchenko wrote:
> On Fri, Jul 1, 2022 at 9:26 PM Colin Foster
> <[email protected]> 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.
> >
> > 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.
>
> ...
>
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> > + if (res) {
> > + regs = devm_ioremap_resource(dev, res);
> > + if (IS_ERR(regs))
> > + return ERR_CAST(regs);
>
> Why can't it be devm_platform_get_and_ioremap_resource() here?
It can... but it invokes prints of "invalid resource" during
initialization.
Here it was implied that I should break the function call out:
https://patchwork.kernel.org/project/netdevbpf/patch/[email protected]/#24917551
>
> regs = devm_platform_get_and_ioremap_resource();
> if (res) {
> if (IS_ERR(regs))
> return ERR_CAST();
> return ...
> }
>
> > + return devm_regmap_init_mmio(dev, regs, config);
> > + }
>
> ...
>
> > + return (map) ? map : ERR_PTR(-ENOENT);
>
> Too many parentheses.
>
> Also you may use short form of ternary operator:
>
> return map ?: ERR_PTR(-ENOENT);
Agreed, and I didn't know about that operator. When Vladimir suggested
it I thought it was a typo. I should've known better.
>
> --
> With Best Regards,
> Andy Shevchenko
On Fri, Jul 1, 2022 at 10:35 PM Colin Foster
<[email protected]> wrote:
> On Fri, Jul 01, 2022 at 10:23:36PM +0200, Andy Shevchenko wrote:
> > On Fri, Jul 1, 2022 at 9:26 PM Colin Foster
> > <[email protected]> wrote:
...
> > > + res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> > > + if (res) {
> > > + regs = devm_ioremap_resource(dev, res);
> > > + if (IS_ERR(regs))
> > > + return ERR_CAST(regs);
> >
> > Why can't it be devm_platform_get_and_ioremap_resource() here?
>
> It can... but it invokes prints of "invalid resource" during
> initialization.
>
> Here it was implied that I should break the function call out:
> https://patchwork.kernel.org/project/netdevbpf/patch/[email protected]/#24917551
Perhaps a comment in the code, so nobody will try to optimize this in
the future.
> > > + return devm_regmap_init_mmio(dev, regs, config);
> > > + }
...
> > > + return (map) ? map : ERR_PTR(-ENOENT);
> >
> > Too many parentheses.
> >
> > Also you may use short form of ternary operator:
> >
> > return map ?: ERR_PTR(-ENOENT);
>
> Agreed, and I didn't know about that operator. When Vladimir suggested
> it I thought it was a typo. I should've known better.
It's easy to remember by thinking of
"X ?: Y" as "X _or_ Y".
--
With Best Regards,
Andy Shevchenko