[PATCH v3 RESEND 2/5] ARM: add SMP support for Broadcom mobile SoCs

[Florian Fainelli]

2014-05-15 11:26 GMT-07:00 Matt Porter <mporter at linaro.org>:
> On Thu, May 15, 2014 at 11:03:49AM -0700, Florian Fainelli wrote:
>> Hi Alex,
>>
>> 2014-05-15 10:58 GMT-07:00 Alex Elder <elder at linaro.org>:
>> > This patch adds SMP support for BCM281XX and BCM21664 family SoCs.
>> >
>> > This feature is controlled with a distinct config option such that a
>> > SMP-enabled multi-v7 binary can be configured to run these SoCs in
>> > uniprocessor mode.  Since this SMP functionality is used for
>> > multiple Broadcom mobile chip families the config option is called
>> > ARCH_BCM_MOBILE_SMP (for lack of a better name).
>> >
>> > On SoCs of this type, the secondary core is not held in reset on
>> > power-on.  Instead it loops in a ROM-based holding pen.  To release
>> > it, one must write into a special register a jump address whose
>> > low-order bits have been replaced with a secondary core's id, then
>> > trigger an event with SEV.  On receipt of an event, the ROM code
>> > will examine the register's contents, and if the low-order bits
>> > match its cpu id, it will clear them and write the value back to the
>> > register just prior to jumping to the address specified.
>> >
>> > The location of the special register is defined in the device tree
>> > using a "secondary-boot-reg" property in a node whose "enable-method"
>> > matches.
>> >
>> > Derived from code originally provided by Ray Jui <rjui at broadcom.com>
>> >
>> > Signed-off-by: Alex Elder <elder at linaro.org>
>> > ---
>> >  arch/arm/mach-bcm/Kconfig   |  18 +++-
>> >  arch/arm/mach-bcm/Makefile  |   3 +
>> >  arch/arm/mach-bcm/platsmp.c | 201 ++++++++++++++++++++++++++++++++++++++++++++
>>
>> Could we make that name a little bit more specific to the mobile SoCs?
>> There are other BCM SoCs either currently supported in this directory
>> (BCM5310X), or making their way to be supported (brcmstb, bcm63xx),
>> and those share nothing with the Mobile SoC SMP code.
>
> Right.
>
>> Maybe we should create another level directory within mach-bcm...
>
> Let's not go that far. The general direction we need to go is to work
> toward removing this code from mach-bcm/ completely. I don't really want
> to see us adding directories and encouraging burying a lot of new files
> in them.

Ok, makes sense.

>
> A unique name will be enough and then we can work toward moving things
> out to drivers/ over time.

Sounds good, thanks!
-- 
Florian