> -----Original Message-----
> From: Alexander Graf [mailto:ag...@suse.de]
> Sent: Thursday, November 27, 2014 10:14 AM
> To: Rivera Jose-B46482; gre...@linuxfoundation.org; a...@arndb.de;
> linux-kernel@vger.kernel.org
> Cc: Yoder Stuart-B08248; Phillips Kim-R1AAHA; Wood Scott-B07421; Hamciuc
> Bogdan-BHAMCIU1; Marginean
> Alexandru-R89243; Thorpe Geoff-R01361; Sharma Bhupesh-B45370; Erez
> Nir-RM30794; Schmitt Richard-B43082
> Subject: Re: [PATCH 1/3 v4] drivers/bus: Added Freescale Management Complex
> APIs
>
>
>
> On 13.11.14 18:54, J. German Rivera wrote:
> > APIs to access the Management Complex (MC) hardware
> > module of Freescale LS2 SoCs. This patch includes
> > APIs to check the MC firmware version and to manipulate
> > DPRC objects in the MC.
> >
> > Signed-off-by: J. German Rivera <german.riv...@freescale.com>
> > Signed-off-by: Stuart Yoder <stuart.yo...@freescale.com>
>
> [...]
>
> > +/**
> > + * Creates an MC I/O object
> > + *
> > + * @dev: device to be associated with the MC I/O object
> > + * @mc_portal_phys_addr: physical address of the MC portal to use
> > + * @mc_portal_size: size in bytes of the MC portal
> > + * @flags: flags for the new MC I/O object
> > + * @new_mc_io: Area to return pointer to newly created MC I/O object
> > + *
> > + * Returns '0' on Success; Error code otherwise.
> > + */
> > +int __must_check fsl_create_mc_io(struct device *dev,
> > + phys_addr_t mc_portal_phys_addr,
> > + uint32_t mc_portal_size,
> > + uint32_t flags, struct fsl_mc_io **new_mc_io)
> > +{
> > + struct fsl_mc_io *mc_io;
> > + void __iomem *mc_portal_virt_addr;
> > + struct resource *res;
> > +
> > + mc_io = devm_kzalloc(dev, sizeof(*mc_io), GFP_KERNEL);
> > + if (mc_io == NULL)
> > + return -ENOMEM;
> > +
> > + mc_io->dev = dev;
> > + mc_io->flags = flags;
> > + mc_io->portal_phys_addr = mc_portal_phys_addr;
> > + mc_io->portal_size = mc_portal_size;
> > + res = devm_request_mem_region(dev,
> > + mc_portal_phys_addr,
> > + mc_portal_size,
> > + "mc_portal");
> > + if (res == NULL) {
> > + dev_err(dev,
> > + "devm_request_mem_region failed for MC portal %#llx\n",
> > + mc_portal_phys_addr);
> > + return -EBUSY;
> > + }
> > +
> > + mc_portal_virt_addr = devm_ioremap_nocache(dev,
> > + mc_portal_phys_addr,
> > + mc_portal_size);
>
> While I can't complain about the device itself, I will note that I think
> it's a pretty bad design decision to expose actual host physical
> addresses in the protocol.
I tend to agree. I'll look into creating a proposed change to the architecture
to have the MC communicate a physical offset of some kind.
> Basically this means that you won't be able to pass a full MC complex
> into a guest, even if you could virtualize IRQ and DMA access unless you
> map it at the exact same location as the host's MC complex.
Right. But is that really an issue in practice?
> Could we at least add a "ranges" property to the MC device description
> and check whether the physical addresses we get are within that range -
> if nothing else, at least as sanity check? Then maybe add some calls in
> the next version that act on that range rather than actual host physical
> addresses?
So you mean something like:
fsl_mc: fsl-mc@80c000000 {
compatible = "fsl,qoriq-mc";
#stream-id-cells = <2>;
reg = <0x00000008 0x0c000000 0 0x40>, /* MC portal base */
<0x00000000 0x08340000 0 0x40000>; /* MC control reg */
ranges = <0x8 0x0 0x8 0x0 0x20000000>;
lpi-parent = <&its>;
};
The physical addresses returned by the MC fall into a 512MB "portal"
region at 0x8_0000_0000 in the physical address map. For now map it 1:1, but
in the
future it could become:
ranges = <0x0 0x0 0x8 0x0 0x20000000>;
...if I can get the hardware architecture changed.
Stuart
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