[PATCH v2 1/7] iommu: Add IOMMU uclass
Mark Kettenis
mark.kettenis at xs4all.nl
Thu Oct 14 21:34:55 CEST 2021
> From: Simon Glass <sjg at chromium.org>
> Date: Mon, 11 Oct 2021 11:00:34 -0600
>
> Hi Mark,
>
> On Sun, 3 Oct 2021 at 12:31, Mark Kettenis <kettenis at openbsd.org> wrote:
> >
> > This uclass is intended to manage IOMMUs on systems where the
> > IOMMUs are not in bypass mode by default. In that case U-Boot
> > cannot ignore the IOMMUs if it wants to use devices that need
> > to do DMA and sit behind such an IOMMU.
> >
> > This initial IOMMU uclass implementation does not implement and
> > device ops and is intended for IOMMUs that have a bypass mode
> > that does not require address translation. Support for IOMMUs
> > that do require address translation is planned and device ops
> > will be defined when support for such IOMMUs will be added.
> >
> > Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> > ---
> > drivers/Kconfig | 2 ++
> > drivers/Makefile | 1 +
> > drivers/core/device.c | 8 +++++++
> > drivers/iommu/Kconfig | 13 +++++++++++
> > drivers/iommu/Makefile | 3 +++
> > drivers/iommu/iommu-uclass.c | 45 ++++++++++++++++++++++++++++++++++++
> > include/dm/uclass-id.h | 1 +
> > include/iommu.h | 16 +++++++++++++
> > 8 files changed, 89 insertions(+)
> > create mode 100644 drivers/iommu/Kconfig
> > create mode 100644 drivers/iommu/Makefile
> > create mode 100644 drivers/iommu/iommu-uclass.c
> > create mode 100644 include/iommu.h
> >
> > diff --git a/drivers/Kconfig b/drivers/Kconfig
> > index 417d6f88c2..b26ca8cf70 100644
> > --- a/drivers/Kconfig
> > +++ b/drivers/Kconfig
> > @@ -50,6 +50,8 @@ source "drivers/i2c/Kconfig"
> >
> > source "drivers/input/Kconfig"
> >
> > +source "drivers/iommu/Kconfig"
> > +
> > source "drivers/led/Kconfig"
> >
> > source "drivers/mailbox/Kconfig"
> > diff --git a/drivers/Makefile b/drivers/Makefile
> > index fd218c9056..166aeb9817 100644
> > --- a/drivers/Makefile
> > +++ b/drivers/Makefile
> > @@ -109,6 +109,7 @@ obj-y += mtd/
> > obj-y += pwm/
> > obj-y += reset/
> > obj-y += input/
> > +obj-y += iommu/
> > # SOC specific infrastructure drivers.
> > obj-y += smem/
> > obj-y += thermal/
> > diff --git a/drivers/core/device.c b/drivers/core/device.c
> > index 29668f6fb3..5f480ad443 100644
> > --- a/drivers/core/device.c
> > +++ b/drivers/core/device.c
> > @@ -28,6 +28,7 @@
> > #include <dm/uclass.h>
> > #include <dm/uclass-internal.h>
> > #include <dm/util.h>
> > +#include <iommu.h>
> > #include <linux/err.h>
> > #include <linux/list.h>
> > #include <power-domain.h>
> > @@ -543,6 +544,13 @@ int device_probe(struct udevice *dev)
> > goto fail;
> > }
> >
> > + if (CONFIG_IS_ENABLED(IOMMU) && dev->parent &&
> > + (device_get_uclass_id(dev) != UCLASS_IOMMU)) {
> > + ret = dev_iommu_probe(dev);
> > + if (ret)
> > + goto fail;
> > + }
> > +
> > ret = device_get_dma_constraints(dev);
> > if (ret)
> > goto fail;
> > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> > new file mode 100644
> > index 0000000000..8cb377560e
> > --- /dev/null
> > +++ b/drivers/iommu/Kconfig
> > @@ -0,0 +1,13 @@
> > +#
> > +# IOMMU devices
> > +#
> > +
> > +menu "IOMMU device drivers"
> > +
> > +config IOMMU
> > + bool "Enable Driver Model for IOMMU drivers"
> > + depends on DM
> > + help
> > + Enable driver model for IOMMU devices.
>
> Need at least three lines. What is an IOMMU? How does it relate to
> other devices?
Not sure if I can describe what an IOMMU is in just a few lines, but
I'll try.
> > +
> > +endmenu
> > diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> > new file mode 100644
> > index 0000000000..f1ceb10150
> > --- /dev/null
> > +++ b/drivers/iommu/Makefile
> > @@ -0,0 +1,3 @@
> > +# SPDX-License-Identifier: GPL-2.0+
> > +
> > +obj-$(CONFIG_IOMMU) += iommu-uclass.o
> > diff --git a/drivers/iommu/iommu-uclass.c b/drivers/iommu/iommu-uclass.c
> > new file mode 100644
> > index 0000000000..5c55df3066
> > --- /dev/null
> > +++ b/drivers/iommu/iommu-uclass.c
> > @@ -0,0 +1,45 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2021 Mark Kettenis <kettenis at openbsd.org>
> > + */
> > +
> > +#define LOG_CATEGORY UCLASS_IOMMU
> > +
> > +#include <common.h>
> > +#include <dm.h>
> > +
> > +#if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA))
> > +int dev_iommu_probe(struct udevice *dev)
>
> Can we rename to dev_iommus_enable()? I like to keep probe for use by
> DM itself so it is confusing to talk about probing in a context other
> than probing a single device.
Sure. That was one of the names I considered myself when writing the
code.
> > +{
> > + struct ofnode_phandle_args args;
> > + struct udevice *dev_iommu;
> > + int i, count, ret = 0;
> > +
> > + count = dev_count_phandle_with_args(dev, "iommus",
> > + "#iommu-cells", 0);
>
> Do you have a binding file you can add to docs/device-tree-bindings ?
The binding is available in Documentation/bindings/iommu/iommu.txt in
the Linux tree. But I don't think copying it into the u-boot tree
makes sense. It will just get out of date. Especially because this
will hopefully be converted into a proper DT schema in the near
future.
> > + for (i = 0; i < count; i++) {
> > + ret = dev_read_phandle_with_args(dev, "iommus",
> > + "#iommu-cells", 0, i, &args);
> > + if (ret) {
> > + debug("%s: dev_read_phandle_with_args failed: %d\n",
> > + __func__, ret);
> > + return ret;
> > + }
> > +
> > + ret = uclass_get_device_by_ofnode(UCLASS_IOMMU, args.node,
> > + &dev_iommu);
> > + if (ret) {
> > + debug("%s: uclass_get_device_by_ofnode failed: %d\n",
> > + __func__, ret);
> > + return ret;
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +#endif
> > +
> > +UCLASS_DRIVER(iommu) = {
> > + .id = UCLASS_IOMMU,
> > + .name = "iommu",
> > +};
> > diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> > index e7edd409f3..56aa981613 100644
> > --- a/include/dm/uclass-id.h
> > +++ b/include/dm/uclass-id.h
> > @@ -61,6 +61,7 @@ enum uclass_id {
> > UCLASS_I2C_MUX, /* I2C multiplexer */
> > UCLASS_I2S, /* I2S bus */
> > UCLASS_IDE, /* IDE device */
> > + UCLASS_IOMMU, /* IOMMU */
> > UCLASS_IRQ, /* Interrupt controller */
> > UCLASS_KEYBOARD, /* Keyboard input device */
> > UCLASS_LED, /* Light-emitting diode (LED) */
> > diff --git a/include/iommu.h b/include/iommu.h
> > new file mode 100644
> > index 0000000000..d17a06a6f3
> > --- /dev/null
> > +++ b/include/iommu.h
> > @@ -0,0 +1,16 @@
> > +#ifndef _IOMMU_H
> > +#define _IOMMU_H
> > +
> > +struct udevice;
> > +
> > +#if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)) && \
> > + CONFIG_IS_ENABLED(IOMMU)
> > +int dev_iommu_probe(struct udevice *dev);
> > +#else
> > +static inline int dev_iommu_probe(struct udevice *dev)
> > +{
> > + return 0;
> > +}
> > +#endif
> > +
> > +#endif
> > --
> > 2.33.0
> >
>
> Regards,
> Simon
>
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