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Commit 300459d5 authored by Huacai Chen's avatar Huacai Chen Committed by Ralf Baechle
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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: default avatarHuacai Chen <chenhc@lemote.com>
Signed-off-by: default avatarHongliang Tao <taohl@lemote.com>
Signed-off-by: default avatarHua Yan <yanh@lemote.com>
Tested-by: default avatarAlex Smith <alex.smith@imgtec.com>
Reviewed-by: default avatarAlex 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: default avatarRalf Baechle <ralf@linux-mips.org>
parent 0e476d91

arch/mips/include/asm/mach-loongson/irq.h

+2 −0
Original line number Diff line number Diff line
@@ -37,5 +37,7 @@ 


#endif



extern void loongson3_ipi_interrupt(struct pt_regs *regs);



#include_next <irq.h>

#endif /* __ASM_MACH_LOONGSON_IRQ_H_ */

arch/mips/include/asm/mach-loongson/loongson.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ extern void mach_prepare_shutdown(void); 
/* environment arguments from bootloader */

extern u32 cpu_clock_freq;

extern u32 memsize, highmemsize;

extern struct plat_smp_ops loongson3_smp_ops;



/* loongson-specific command line, env and memory initialization */

extern void __init prom_init_memory(void);

arch/mips/loongson/common/init.c

+2 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
 */



#include <linux/bootmem.h>

#include <asm/smp-ops.h>



#include <loongson.h>
@@ -33,6 +34,7 @@ void __init prom_init(void) 


	/*init the uart base address */

	prom_init_uart_base();

	register_smp_ops(&loongson3_smp_ops);

}



void __init prom_free_prom_memory(void)

arch/mips/loongson/common/setup.c

+3 −5
Original line number Diff line number Diff line
@@ -18,9 +18,6 @@ 
#include <linux/screen_info.h>

#endif



void (*__wbflush)(void);

EXPORT_SYMBOL(__wbflush);



static void wbflush_loongson(void)

{

	asm(".set\tpush\n\t"
@@ -32,10 +29,11 @@ static void wbflush_loongson(void) 
	    ".set mips0\n\t");

}



void (*__wbflush)(void) = wbflush_loongson;

EXPORT_SYMBOL(__wbflush);



void __init plat_mem_setup(void)

{

	__wbflush = wbflush_loongson;



#ifdef CONFIG_VT

#if defined(CONFIG_VGA_CONSOLE)

	conswitchp = &vga_con;

arch/mips/loongson/loongson-3/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -2,3 +2,5 @@ 
# Makefile for Loongson-3 family machines

#

obj-y			+= irq.o



obj-$(CONFIG_SMP)	+= smp.o