If an ARM system has multiple cpus in the same socket and the
kernel is booted with maxcpus=1, secondary cpus are possible but
not present due to how platform_smp_prepare_cpus() is called.
Since most typical ARM processors don't actually support physical
hotplug, initialize the present map to be equal to the possible
map in generic ARM SMP code. Also, always call
platform_smp_prepare_cpus() as long as max_cpus is non-zero (0
means no SMP) to allow platform code to do any SMP setup.
After applying this patch it's possible to boot an ARM system
with maxcpus=1 on the command line and then hotplug in secondary
cpus via sysfs. This is more in line with how x86 does things.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: David Brown <davidb@codeaurora.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Rather than having each platform class provide a mach/smp.h header for
smp_cross_call(), arrange for them to register the function with the
core ARM SMP code instead.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add SMP support for ag5evm and the sh73a0 processor.
Onlining and offlining works well, but at this point
offlined processor cores are not put into sleep mode.
There is no spinlock for syncing the secondary core
with the first one in this implementation. The code
instead relies on the cpu_online() check in __cpu_up().
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Add SMP base support for R-Mobile / SH-Mobile processors.
This patch contains all base code to support CONFIG_SMP
regardless of ARCH_SHMOBILE processor type. Both local timer
and CPU hotplug are supported, but no processor specific
code is included.
At this point only the default behavior is in place, so
a single core will always be used even though CONFIG_SMP
is enabled on multicore systems.
The SMP Kconfig entry for arch/arm/Kconfig is excluded from
this patch to simplify merging.
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Stephen Boyd