From: Colin Foster <colin.foster@in-advantage.com>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
Lee Jones <lee.jones@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Andrew Lunn <andrew@lunn.ch>,
Heiner Kallweit <hkallweit1@gmail.com>,
Russell King <linux@armlinux.org.uk>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Lars Povlsen <lars.povlsen@microchip.com>,
Steen Hegelund <Steen.Hegelund@microchip.com>,
"UNGLinuxDriver@microchip.com" <UNGLinuxDriver@microchip.com>,
Linus Walleij <linus.walleij@linaro.org>,
Wolfram Sang <wsa@kernel.org>,
Terry Bowman <terry.bowman@amd.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Arnd Bergmann <arnd@kernel.org>
Subject: Re: [PATCH v11 net-next 1/9] mfd: ocelot: add helper to get regmap from a resource
Date: Tue, 28 Jun 2022 10:25:18 -0700 [thread overview]
Message-ID: <20220628172518.GA855398@euler> (raw)
In-Reply-To: <20220628160809.marto7t6k24lneau@skbuf>
Hi Vladimir,
On Tue, Jun 28, 2022 at 04:08:10PM +0000, Vladimir Oltean wrote:
> On Tue, Jun 28, 2022 at 01:17:01AM -0700, Colin Foster wrote:
> > diff --git a/include/linux/mfd/ocelot.h b/include/linux/mfd/ocelot.h
> > new file mode 100644
> > index 000000000000..5c95e4ee38a6
> > --- /dev/null
> > +++ b/include/linux/mfd/ocelot.h
> > @@ -0,0 +1,27 @@
> > +/* 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_platform_init_regmap_from_resource(struct platform_device *pdev,
> > + unsigned int index,
> > + const struct regmap_config *config)
>
> I think this function name is too long (especially if you're going to
> also introduce ocelot_platform_init_regmap_from_resource_optional),
> and I have the impression that the "platform_init_" part of the name
> doesn't bring too much value. How about ocelot_regmap_from_resource()?
I thought the same thing after your first email. My thought was "how do
I indent that?" :-)
>
> > +{
> > + struct resource *res;
> > + u32 __iomem *regs;
> > +
> > + regs = devm_platform_get_and_ioremap_resource(pdev, index, &res);
> > +
> > + if (!res)
> > + return ERR_PTR(-ENOENT);
> > + else if (IS_ERR(regs))
> > + return ERR_CAST(regs);
> > + else
> > + return devm_regmap_init_mmio(&pdev->dev, regs, config);
> > +}
> > --
> > 2.25.1
> >
>
> To illustrate what I'm trying to say, these would be the shim
> definitions:
>
> static inline struct regmap *
> ocelot_regmap_from_resource(struct platform_device *pdev,
> unsigned int index,
> const struct regmap_config *config)
> {
> struct resource *res;
> void __iomem *regs;
>
> regs = devm_platform_get_and_ioremap_resource(pdev, index, &res);
> if (IS_ERR(regs))
> return regs;
>
> return devm_regmap_init_mmio(&pdev->dev, regs, config);
> }
>
> static inline struct regmap *
> ocelot_regmap_from_resource_optional(struct platform_device *pdev,
> unsigned int index,
> const struct regmap_config *config)
> {
> struct resource *res;
> void __iomem *regs;
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> if (!res)
> return NULL;
>
> regs = devm_ioremap_resource(&pdev->dev, r);
> if (IS_ERR(regs))
> return regs;
>
> return devm_regmap_init_mmio(&pdev->dev, regs, config);
> }
>
> and these would be the full versions:
>
> static struct regmap *
> ocelot_regmap_from_mem_resource(struct device *dev, struct resource *res,
> const struct regmap_config *config)
> {
> void __iomem *regs;
>
> regs = devm_ioremap_resource(dev, r);
> if (IS_ERR(regs))
> return regs;
>
> return devm_regmap_init_mmio(dev, regs, config);
> }
>
> static struct regmap *
> ocelot_regmap_from_reg_resource(struct device *dev, struct resource *res,
> const struct regmap_config *config)
> {
> /* Open question: how to differentiate SPI from I2C resources? */
My expectation is to set something up in drivers/mfd/ocelot-{spi,i2c}.c
and have an if/else / switch. PCIe might actually be our first hardware
spin.
> return ocelot_spi_init_regmap(dev->parent, dev, res);
> }
>
> 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;
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> if (res)
> return ocelot_regmap_from_mem_resource(dev, res, config);
>
> /*
> * Fall back to using IORESOURCE_REG, which is possible in an
> * MFD configuration
> */
> res = platform_get_resource(pdev, IORESOURCE_REG, index);
> if (res)
> return ocelot_regmap_from_reg_resource(dev, res, config);
>
> return NULL;
> }
>
> 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);
> }
>
> I hope I didn't get something wrong, this is all code written within the
> email client, so it is obviously not compiled/tested....
Yep - I definitely get the point. And thanks for the review.
The other (bigger?) issue is around how this MFD can be loaded as a
module. Right now it is pretty straightforward to say
#if IS_ENABLED(CONFIG_MFD_OCELOT). Theres a level of nuance if
CONFIG_MFD_OCELOT=m while the child devices are compiled in
(CONFIG_PINCTRL_MICROCHIP_SGPIO=y for example). It still feels like this
code belongs somewhere in platform / resource / device / mfd...?
It might be perfectly valid to have multiple SGPIO controllers - one
local and one remote / SPI. But without the CONFIG_MFD_OCELOT module
loaded, I don't think the SGPIO module would work.
This patch set deals with the issue by setting MFD_OCELOT to a boolean -
but in the long run I think a module makes sense. I admittedly haven't
spent enough time researching (bashing my head against the wall) this,
but this seems like a good opportunity to at least express that I'm
expecting to have to deal with this issue soon. I met with Alexandre at
ELC this past week, and he said Arnd (both added to CC) might be a good
resource - but again I'd like to do a little more searching before
throwing it over the wall.
next prev parent reply other threads:[~2022-06-28 17:25 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-28 8:17 [PATCH v11 net-next 0/9] add support for VSC7512 control over SPI Colin Foster
2022-06-28 8:17 ` [PATCH v11 net-next 1/9] mfd: ocelot: add helper to get regmap from a resource Colin Foster
2022-06-28 12:50 ` Andy Shevchenko
2022-06-28 15:33 ` Vladimir Oltean
2022-06-28 16:08 ` Vladimir Oltean
2022-06-28 17:25 ` Colin Foster [this message]
2022-06-28 18:47 ` Vladimir Oltean
2022-06-28 18:56 ` Vladimir Oltean
2022-06-28 19:04 ` Andy Shevchenko
2022-06-28 19:56 ` Colin Foster
2022-06-29 17:53 ` Vladimir Oltean
2022-06-29 20:39 ` Colin Foster
2022-06-29 23:08 ` Vladimir Oltean
2022-06-29 23:54 ` Colin Foster
2022-06-30 7:54 ` Lee Jones
2022-06-30 13:11 ` Vladimir Oltean
2022-06-30 20:09 ` Colin Foster
2022-07-01 16:21 ` Vladimir Oltean
2022-07-01 17:18 ` Colin Foster
2022-07-02 12:42 ` Vladimir Oltean
2022-07-02 16:17 ` Colin Foster
2022-06-28 8:17 ` [PATCH v11 net-next 2/9] net: mdio: mscc-miim: add ability to be used in a non-mmio configuration Colin Foster
2022-06-28 16:26 ` Vladimir Oltean
2022-06-28 18:31 ` Colin Foster
2022-06-28 8:17 ` [PATCH v11 net-next 3/9] pinctrl: ocelot: allow pinctrl-ocelot to be loaded as a module Colin Foster
2022-06-28 12:53 ` Andy Shevchenko
2022-06-28 18:25 ` Colin Foster
2022-06-28 19:00 ` Andy Shevchenko
2022-06-30 11:56 ` Linus Walleij
2022-06-28 8:17 ` [PATCH v11 net-next 4/9] pinctrl: ocelot: add ability to be used in a non-mmio configuration Colin Foster
2022-06-28 8:17 ` [PATCH v11 net-next 5/9] pinctrl: microchip-sgpio: allow sgpio driver to be used as a module Colin Foster
2022-06-28 12:55 ` Andy Shevchenko
2022-06-28 8:17 ` [PATCH v11 net-next 6/9] pinctrl: microchip-sgpio: add ability to be used in a non-mmio configuration Colin Foster
2022-06-28 8:17 ` [PATCH v11 net-next 7/9] resource: add define macro for register address resources Colin Foster
2022-06-28 8:17 ` [PATCH v11 net-next 8/9] dt-bindings: mfd: ocelot: add bindings for VSC7512 Colin Foster
2022-06-28 13:15 ` Rob Herring
2022-06-28 18:19 ` Colin Foster
2022-06-30 13:17 ` Vladimir Oltean
2022-06-28 8:17 ` [PATCH v11 net-next 9/9] mfd: ocelot: add support for the vsc7512 chip via spi Colin Foster
2022-06-28 20:07 ` Randy Dunlap
2022-06-28 20:24 ` Colin Foster
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