Accessing indirect DCRs is done via a pair of address/data DCRs.
Such accesses are thus inherently racy, vs. interrupts, preemption
and possibly SMP if 4xx SMP cores are ever used.
This updates the mfdcri/mtdcri macros in dcr-native.h (which were
so far unused) to use a spinlock.
In addition, add some common definitions to a new dcr-regs.h file.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
With the base stored in dcr_host_t, there's no need for callers to pass
the dcr_n into dcr_unmap(). In fact this removes the possibility of them
passing the incorrect value, which would then be iounmap()'ed.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Now that all users of dcr_read()/dcr_write() add the dcr_host_t.base, we
can save them the trouble and do it in dcr_read()/dcr_write().
As some background to why we just went through all this jiggery-pokery,
benh sayeth:
Initially the goal of the dcr_read/dcr_write routines was to operate like
mfdcr/mtdcr which take absolute DCR numbers. The reason is that on 4xx
hardware, indirect DCR access is a pain (goes through a table of
instructions) and it's useful to have the compiler resolve an absolute DCR
inline.
We decided that wasn't worth the API bastardisation since most places
where absolute DCR values are used are low level 4xx-only code which may
as well continue using mfdcr/mtdcr, while the new API is designed for
device "instances" that can exist on 4xx and Axon type platforms and may
be located at variable DCR offsets.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
In its current form, dcr_map() doesn't remember the base address you passed
it, which means you need to store it somewhere else. Rather than adding the
base to another struct it seems simpler to store it in the dcr_host_t.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Getting BenH's new EMAC driver working on 440GP, I found some more
problems in the native mode paths of the new DCR code:
- dcr_map() is supposed to return a dcr_host_t, but the native
version is a macro that doesn't expand to an expression. With native
DCRs, dcr_host_t is an empty structure, so we just use a constructor
expression instead.
- dcr_unmap() uses {} instead of the safer do {} while (0)
idiom to implement a no-op
Here's a fix.
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
On 85xx we don't build in dcr support because the core doesn't implement the
instructions. This caused problems when building an 85xx kernel. Additionally
made it so we only build __mtdcr/__mfdcr if we are CONFIG_PPC_DCR_NATIVE.
The 85xx build issue wasPointed out by Dai Haruki.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
This patch adds new dcr_map/dcr_read/dcr_write accessors for DCRs that
can be used by drivers to transparently address either native DCRs or
memory mapped DCRs. The implementation for memory mapped DCRs is done
after the binding being currently worked on for SLOF and the Axon
chipset. This patch enables it for the cell native platform
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
