From: Robin Murphy <robin.murphy@arm.com>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: f.fainelli@gmail.com, robh+dt@kernel.org, ardb@kernel.org,
hch@infradead.org, narmstrong@baylibre.com, dwmw2@infradead.org,
linux@armlinux.org.uk, catalin.marinas@arm.com, arnd@arndb.de,
will@kernel.org
Subject: Re: [RFC 02/13] driver core: Introduce MMIO configuration
Date: Tue, 2 Mar 2021 11:29:10 +0000 [thread overview]
Message-ID: <644fd416-ab64-f1cc-ffb0-ea5649e3b600@arm.com> (raw)
In-Reply-To: <20210226140305.26356-3-nsaenzjulienne@suse.de>
On 2021-02-26 14:02, Nicolas Saenz Julienne wrote:
> Some devices might inadvertently sit on buses that don't support 64bit
> MMIO access, and need a mechanism to query these limitations without
> prejudice to other buses in the system (i.e. defaulting to 32bit access
> system wide isn't an option).
>
> Introduce a new bus callback, 'mmio_configure(),' which will take care
> of populating the relevant device properties based on the bus'
> limitations.
Devil's advocate: there already exist workarounds for 8-bit and/or
16-bit accesses not working in various places, does it make sense for a
64-bit workaround to be so wildly different and disjoint?
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---
> arch/Kconfig | 8 ++++++++
> drivers/base/dd.c | 6 ++++++
> include/linux/device.h | 3 +++
> include/linux/device/bus.h | 3 +++
> 4 files changed, 20 insertions(+)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 2bb30673d8e6..ba7f246b6b9d 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -1191,6 +1191,14 @@ config ARCH_SPLIT_ARG64
> config ARCH_HAS_ELFCORE_COMPAT
> bool
>
> +config ARCH_HAS_64BIT_MMIO_BROKEN
> + bool
> + depends on 64BIT
As mentioned previously, 32-bit systems may not need the overrides for
kernel I/O accessors, but they could still need the same workarounds for
the memory-mapping implications (if this is to be a proper generic
mechanism).
> + default n
Tip: it is always redundant to state that.
Robin.
> + help
> + Arch might contain busses unable to perform 64bit mmio accessses on
> + an otherwise 64bit system.
> +
> source "kernel/gcov/Kconfig"
>
> source "scripts/gcc-plugins/Kconfig"
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 9179825ff646..8086ce8f17a6 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -538,6 +538,12 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> goto probe_failed;
> }
>
> + if (dev->bus->mmio_configure) {
> + ret = dev->bus->mmio_configure(dev);
> + if (ret)
> + goto probe_failed;
> + }
> +
> if (driver_sysfs_add(dev)) {
> pr_err("%s: driver_sysfs_add(%s) failed\n",
> __func__, dev_name(dev));
> diff --git a/include/linux/device.h b/include/linux/device.h
> index ba660731bd25..bd94aa0cbd72 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -553,6 +553,9 @@ struct device {
> #ifdef CONFIG_DMA_OPS_BYPASS
> bool dma_ops_bypass : 1;
> #endif
> +#if defined(CONFIG_ARCH_HAS_64BIT_MMIO_BROKEN)
> + bool mmio_64bit_broken:1;
> +#endif
> };
>
> /**
> diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h
> index 1ea5e1d1545b..680dfc3b4744 100644
> --- a/include/linux/device/bus.h
> +++ b/include/linux/device/bus.h
> @@ -59,6 +59,8 @@ struct fwnode_handle;
> * bus supports.
> * @dma_configure: Called to setup DMA configuration on a device on
> * this bus.
> + * @mmio_configure: Called to setup MMIO configuration on a device on
> + * this bus.
> * @pm: Power management operations of this bus, callback the specific
> * device driver's pm-ops.
> * @iommu_ops: IOMMU specific operations for this bus, used to attach IOMMU
> @@ -103,6 +105,7 @@ struct bus_type {
> int (*num_vf)(struct device *dev);
>
> int (*dma_configure)(struct device *dev);
> + int (*mmio_configure)(struct device *dev);
>
> const struct dev_pm_ops *pm;
>
>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-03 19:51 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 14:02 [RFC 00/13] Generic way of dealing with broken 64-bit buses Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 01/13] dt-bindings: Introduce 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 02/13] driver core: Introduce MMIO configuration Nicolas Saenz Julienne
2021-03-02 11:29 ` Robin Murphy [this message]
2021-03-02 14:09 ` Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 03/13] of: device: Introduce of_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 04/13] driver core: plafrom: Introduce platform_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 05/13] pci: Introduce pci_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 06/13] device core: Introduce dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 07/13] arm64: Mark ARCH_MVEBU as needing broken 64bit MMIO support Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 08/13] arm64: dts: marvell: armada-ap80x: Mark config-space bus as 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 09/13] iommu/arm-smmu: Make use of dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-03-02 9:32 ` Arnd Bergmann
2021-03-02 12:42 ` Nicolas Saenz Julienne
2021-03-02 11:07 ` Robin Murphy
2021-03-02 13:38 ` Nicolas Saenz Julienne
2021-03-03 8:44 ` Arnd Bergmann
2021-02-26 14:03 ` [RFC 10/13] iommu/arm-smmu-impl: Get rid of Marvell's implementation details Nicolas Saenz Julienne
2021-03-02 11:40 ` Robin Murphy
2021-03-02 14:06 ` Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 11/13] arm64: Mark ARCH_BCM2835 as needing broken 64bit MMIO support Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 12/13] ARM: dts: bcm2711: Mark PCIe bus as 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-02-26 14:30 ` Arnd Bergmann
2021-02-26 18:06 ` Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=644fd416-ab64-f1cc-ffb0-ea5649e3b600@arm.com \
--to=robin.murphy@arm.com \
--cc=ardb@kernel.org \
--cc=arnd@arndb.de \
--cc=catalin.marinas@arm.com \
--cc=devicetree@vger.kernel.org \
--cc=dwmw2@infradead.org \
--cc=f.fainelli@gmail.com \
--cc=hch@infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=narmstrong@baylibre.com \
--cc=nsaenzjulienne@suse.de \
--cc=robh+dt@kernel.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).