Messages in this thread | | | From | Stuart Yoder <> | Subject | RE: [PATCH 1/3 v4] drivers/bus: Added Freescale Management Complex APIs | Date | Mon, 1 Dec 2014 22:53:47 +0000 |
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> -----Original Message----- > From: Alexander Graf [mailto:agraf@suse.de] > Sent: Thursday, November 27, 2014 10:14 AM > To: Rivera Jose-B46482; gregkh@linuxfoundation.org; arnd@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.Rivera@freescale.com> > > Signed-off-by: Stuart Yoder <stuart.yoder@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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