MIPS: Loongson 3: Add Loongson-3 SMP support
authorHuacai Chen <chenhc@lemote.com>
Fri, 21 Mar 2014 10:44:08 +0000 (18:44 +0800)
committerRalf Baechle <ralf@linux-mips.org>
Mon, 31 Mar 2014 16:17:12 +0000 (18:17 +0200)
commit300459d558725cdada5ddebbe52c24ef6e1853d3
treefb93b1d6c2845af29cce7c06ae35a3b88b7f6431
parent0e476d91244ec6a9f6be3eb1963627340d031f99
MIPS: Loongson 3: Add Loongson-3 SMP support

IPI registers of Loongson-3 include IPI_SET, IPI_CLEAR, IPI_STATUS,
IPI_EN and IPI_MAILBOX_BUF. Each bit of IPI_STATUS indicate a type of
IPI and IPI_EN indicate whether the IPI is enabled. The sender write 1
to IPI_SET bits generate IPIs in IPI_STATUS, and receiver write 1 to
bits of IPI_CLEAR to clear IPIs. IPI_MAILBOX_BUF are used to deliver
more information about IPIs.

Why we change code in arch/mips/loongson/common/setup.c?

If without this change, when SMP configured, system cannot boot since
it hang at printk() in cgroup_init_early(). The root cause is:

console_trylock()
  \-->down_trylock(&console_sem)
    \-->raw_spin_unlock_irqrestore(&sem->lock, flags)
      \-->_raw_spin_unlock_irqrestore()(SMP/UP have different versions)
        \-->__raw_spin_unlock_irqrestore()  (following is the SMP case)
          \-->do_raw_spin_unlock()
            \-->arch_spin_unlock()
              \-->nudge_writes()
                \-->mb()
                  \-->wbflush()
                    \-->__wbflush()

In previous code __wbflush() is initialized in plat_mem_setup(), but
cgroup_init_early() is called before plat_mem_setup(). Therefore, In
this patch we make changes to avoid boot failure.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Hongliang Tao <taohl@lemote.com>
Signed-off-by: Hua Yan <yanh@lemote.com>
Tested-by: Alex Smith <alex.smith@imgtec.com>
Reviewed-by: Alex Smith <alex.smith@imgtec.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/6638
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
arch/mips/include/asm/mach-loongson/irq.h
arch/mips/include/asm/mach-loongson/loongson.h
arch/mips/loongson/common/init.c
arch/mips/loongson/common/setup.c
arch/mips/loongson/loongson-3/Makefile
arch/mips/loongson/loongson-3/irq.c
arch/mips/loongson/loongson-3/smp.c [new file with mode: 0644]
arch/mips/loongson/loongson-3/smp.h [new file with mode: 0644]